Publications

Microgels show advantages over bulk hydrogels due to convenient control over microgel size and composition, and the ability to use microgels to modularly construct larger hierarchical scaffold hydrogel materials. Here, supramolecular chemistry is used to formulate supramolecular polymer, dynamic microgels solely held together by non-covalent interactions. Four-fold hydrogen bonding ureido-pyrimidinone (UPy) monomers with different functionalities are applied to precisely tune microgel properties in a modular way, via variations in monomer concentration, bifunctional crosslinker ratio, and the incorporation of supramolecular dyes and peptides. Functionalization with a bioactive supramolecular cell-adhesive peptide induced selectivity of cells toward the bioactive microgels over non-active, non-functionalized versions. Importantly, the supramolecular microgels can also be applied as microscale building blocks into supramolecular bulk macrogels with tunable dynamic behavior: a robust and weak macrogel, where the micro- and macrogels are composed of similar molecular building blocks. In a robust macrogel, microgels act as modular micro-building blocks, introducing multi-compartmentalization, while in a weak macrogel, microgels reinforce and enhance mechanical properties. This work demonstrates the potential to modularly engineer higher-length-scale structures using small molecule supramolecular monomers, wherein microgels serve as versatile and modular micro-building units.

JTD Keywords: Biomaterials, Cell culture, Droplet-based microfluidics, Droplet‐based microfluidics, Fabrication, Hydrogel, Hydrogels, Microgel, Multiscale modularity, Scaffolds, Siz, Supramolecular biomaterial, Synthetic extracellular matri, Synthetic extracellular matrix

Porous zirconia scaffolds manufactured using polymer-infiltrated ceramic network (PICN) and additive manufacturing technologies are emerging as promising alternatives to traditional ceramic materials in dental restorations. However, incomplete osseointegration and bacterial infections still represent challenges for the long-term performance of this new composite material. To address this, the present study aims to investigate the effect of peptide biofunctionalization on the biological performance of infiltrated zirconia scaffold surfaces. The samples used in the work consisted of a 3D-printed zirconia scaffold infiltrated with a dimethacrylate copolymer. Surface biofunctionalization was achieved using a synthetic platform containing the cell-adhesive sequence RGD and the antibacteria LF1-11 peptide (RGD-LF). The attachment of the molecule was characterized through fluorescence confocal laser scanning microscopy and X-ray photoelectron spectroscopy. The biological performance of the samples was evaluated in terms of human mesenchymal stem cell adhesion and early attachment of S. aureus. The physicochemical characterization verified the successful anchoring of the biomolecule to the surface, leading to a peptide density of 288 pmol/cm2. 2 . The biological assays confirmed the potential of RGD-LF to improve cell adhesion and spreading. In this sense, the average cell area increased fourfold in the biofunctionalized surface. Regarding bacterial adhesion, it was demonstrated that RGD-LF significantly inhibited it, reducing early adhesion by half compared to the untreated surface. Overall, this study provides valuable insights into the biofunctionalization of polymer-infiltrated 3D scaffolds for the development of cell-instructive and antibacterial surfaces tailored for dental applications.

JTD Keywords: Antibacteria, Biocompatibility, Cell adhesion, Composite, Dental ceramics, Direct ink writing, Fabrication, Infiltrated zirconia scaffolds, Mechanical-properties, Peptide biofunctionalization, Picn material, Strength, Surface, Topograph, Wear behavior

Surface plasmon resonance (SPR) is a key technique in developing sensor platforms for clinical diagnostics, drug discovery, food quality, and environmental monitoring applications. While prism-coupled (Kretschmann) SPR remains a "gold-standard" for laboratory work-flows due to easier fabrication, handling and high through put, other configurations such as grating-coupled SPR (GC-SPR) and wave-guide mode SPR are yet to fulfil their technology potential. This work evaluates the technical aspects influencing the performance of GC-SPR and reviews recent progress in the fabrication of such platforms. In principle, the GC-SPR involves the illumination of the plasmonic metal film with periodic gratings to excite the surface plasmons (SP) via diffraction-based phase matching. The real performance of the GC-SPR is, however, heavily influenced by the topography of the grating structures produced via top-down lithography techniques. This review discusses latest in approaches to achieve consistent plasmonic gratings with uniform features and periodicity over a large scale and explores the choice of plasmon-active and substrate material for enhanced performance. The review also provides insights into the different GC-SPR measurement configurations and highlights on opportunities with their potential applications as biosensors with translational capabilities. A review on recent progress in the realization of grating-coupled and wave-guide mode surface plasmon resonance (SPR) platforms which have seen very limited progress toward diagnostics applications in comparison to Kretchmann configured SPR. Sophisticated topography manipulation during large-area nanofabrication, integration of emerging nanomaterials, and machine learning-based data analytics are expected to overcome concurrent challenges toward clinical adoption of grating-coupled SPR in coming years. image

JTD Keywords: Aluminum, Biosensor, Chemical sensor, Compact, Fabrication methods, Gc-spr, Gold, Lase, Lithography, Nanogratings, Performance, Plasmonics, Sensitivity enhancement, Sp, Spr sensor

To improve the features of alginate-based hydrogels in physiological conditions, Ca2+-crosslinked 2 +-crosslinked semi interpenetrated hydrogels formed by poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid and alginate (PEDOT/Alg) were subjected to a treatment with glyoxal to form a dual ionic/covalent network. The covalent network density was systematically varied by considering different glyoxalization times (tG). t G ). The content of Ca2+ was significantly higher for the untreated hydrogel than for the glyoxalized ones, while the properties of the hydrogels were found to largely depend on t G . The porosity and swelling capacity decreased with increasing while the stiffness and electrical conductance retention capacity increased with t G . The potentiodynamic response of the hydrogels notably depended on the amount of conformational restraints introduced by the glyoxal, which is a very short crosslinker. Thus, the re-accommodation of the polymer chains during the cyclic potential scans became more difficult with increasing number of covalent crosslinks. This information was used to improve the performance of untreated PEDOT/Alg as electrochemical sensor of hydrogen peroxide by simply applying a tG G of 5 min. Overall, the control of the properties of glyoxalized hydrogels through tG G is very advantageous and can be used as an on-demand strategy to improve the performance of such materials depending on the application.

JTD Keywords: 4-ethylenedioxythiophene), Acid, Behavior, Cell, Conducting hydrogels, Dual networ, Electrochemical biosensor, Fabrication, Gel, Linke, Microspheres, Peroxidase, Poly(3, Polyvinyl-alcohol, Semi-interpenetrated hydrogel

Biofabrication of three-dimensional (3D) cultures through the 3D Bioprinting technique opens new perspectives and applications of cell-laden hydrogels. However, to continue with the progress, new BioInks with specific properties must be carefully designed. In this study, we report the synthesis and 3D Bioprinting of an electroconductive BioInk made of gelatin/fibrinogen hydrogel, C2C12 mouse myoblast and 5% w/w of conductive poly (3,4-ethylenedioxythiophene) nanoparticles (PEDOT NPs). The influence of PEDOT NPs, incorporated in the cellladen BioInk, not only showed a positive effect in cells viability, differentiation and myotube functionalities, also allowed the printed constructs to behaved as BioCapacitors. Such devices were able to electrochemically store a significant amount of energy (0.5 mF/cm2), enough to self-stimulate as BioActuator, with typical contractions ranging from 27 to 38 mu N, during nearly 50 min. The biofabrication of 3D constructs with the proposed electroconductive BioInk could lead to new devices for tissue engineering, biohybrid robotics or bioelectronics.

JTD Keywords: 3d bioprinting, Animal, Animals, Bioactuator, Bioactuators, Biocapacitor, Biofabrication, Bioprinting, Biosensing techniques, C2c12 myoblasts, Cells, Chemistry, Electric conductivity, Electroconductive, Electroconductive bioink, Ethylenedioxythiophenes, Genetic procedures, Hydrogel, Hydrogels, Mice, Mouse, Pedot nps, Pedot nps,3d bioprinting,electroconductive bioink,bioactuator,biocapacito, Poly (3,4-ethylenedioxythiophene) nanoparticle, Printing, three-dimensional, Procedures, Skeletal-muscle,cytotoxicity,polymer, Synthesis (chemical), Three dimensional printing, Tissue engineering, Tissue scaffolds

Tissue engineering holds great promise for biomedical research and healthcare, offering alternatives to animal models and enabling tissue regeneration and organ transplantation. Three-dimensional (3D) bioprinting stands out for its design flexibility and reproducibility. Here, we present an integrated fluorescent light sheet bioprinting and imaging system that combines high printing speed (0.66 mm3 /s) and resolution (9 μm) with light sheet-based imaging. This approach employs direct laser patterning and a static light sheet for confined voxel crosslinking in photocrosslinkable materials. The developed bioprinter enables real-time monitoring of hydrogel crosslinking using fluorescent recovery after photobleaching (FRAP) and brightfield imaging as well as in situ light sheet imaging of cells. Human fibroblasts encapsulated in a thiol-ene click chemistry-based hydrogel exhibited high viability (83% ± 4.34%) and functionality. Furthermore, full-thickness skin constructs displayed characteristics of both epidermal and dermal layers and remained viable for 41 days. The integrated approach demonstrates the capabilities of light sheet bioprinting, offering high speed, resolution, and real-time characterization. Future enhancements involving solid-state laser scanning devices such as acousto-optic deflectors and modulators will further enhance resolution and speed, opening new opportunities in light-based bioprinting and advancing tissue engineering. This article is protected by copyright. All rights reserved.This article is protected by copyright. All rights reserved.

JTD Keywords: cadherin, collagen, culture, differentiation, fluorescence microscopy, full-thickness skin model, hydrogels, light sheet bioprinter, light sheet fluorescence microscopy, proliferation, survival, tissue engineering, Animal, Animals, Biofabrication, Bioprinting, Cell culture, Crosslinking, Fluorescence, Fluorescence microscopy, Full-thickness skin model, Hair follicle, Human, Humans, Hydrogel, Hydrogels, Image resolution, Laser patterning, Light sheet, Light sheet bioprinter, Light sheet fluorescence microscopy, Molecular biology, Photobleaching, Printing, three-dimensional, Procedures, Reproducibility, Reproducibility of results, Skin model, Three dimensional printing, Tissue, Tissue engineering, Tissue regeneration, Tissue scaffolds, Tissues engineerings

JTD Keywords: Biofabrication,full-thickness skin model,light sheet bioprinter,light sheet fluorescence microscopy,tissue engineerin

The immobilization of vesicles has been conceptualized as a method to functionalize biointerfaces. However, the preservation of their integrity post immobilization remains a considerable challenge. Interfacial interactions can cause vesicle rupture upon close surface contact and non-specific protein adsorption impairing surface functions. To date, immobilization of vesicles has relied solely on either entrapment or prior modification of vesicles, both of which require laborious preparation and limit their applications. This work develops a bioinspired strategy to pin vesicles without prior modification while preserving their intact shape. This work introduces antifouling diblock copolymers and ultrathin surface-attached hydrogels containing a brush-like interface consisting of a bottle brush copolymer of N-(2-hydroxypropyl) methacrylamide (HPMA) and N-(3-methacrylamidopropyl)-N,N-dimethyldodecan-1-aminiumiodide (C12+). The presence of positive charges generates an attractive force that pulls vesicles toward the surface. At the surface, the amphiphilic properties of the combs facilitate their insertion into the membrane, mimicking the harpooning mechanism observed in antimicrobial peptides. Importantly, the antifouling poly(HPMA) backdrop serves to safeguard the vesicles by preventing deformation and breakage. Using a combination of thermodynamic analysis, surface plasmon resonance, and confocal laser scanning microscopy, this work demonstrates the efficiency of this biomimetic system to capture vesicles while maintaining an antifouling interface necessary for bioapplications. This work presents a novel supramolecular approach that combines three key elements: long-range attraction, vesicle pinning, and short-range repulsion to attract and harpoon vesicles, while protecting them at the surface. This work envisions these coatings as universal and biocompatible platforms that can be used not only to study vesicle interactions, but also as tools for biomedical applications.image

JTD Keywords: Antifouling coatings, Coatings, Delivery, Extracellular vesicles, Fabrication, Hydrogel, Janus dendrimers, Lipid vesicles, Liposomes, Membrane insertion, Polymer brushes, Proteins, Surface-energy components, Ultrathin surface-attached hydrogels, Vesicle pinning

Although multifunctional wearable devices have been widely investigated for healthcare systems, augmented/virtual realities, and telemedicines, there are few reports on multiple signal monitoring and logical signal processing by using one single nanomaterial without additional algorithms or rigid application-specific integrated circuit chips. Here, multifunctional intelligent wearable devices are developed using monolithically patterned gold nanowires for both signal monitoring and processing. Gold bulk and hollow nanowires show distinctive electrical properties with high chemical stability and high stretchability. In accordance, the monolithically patterned gold nanowires can be used to fabricate the robust interfaces, programmable sensors, on-demand heating systems, and strain-gated logical circuits. The stretchable sensors show high sensitivity for strain and temperature changes on the skin. Furthermore, the micro-wrinkle structures of gold nanowires exhibit the negative gauge factor, which can be used for strain-gated logical circuits. Taken together, this multifunctional intelligent wearable device would be harnessed as a promising platform for futuristic electronic and biomedical applications.© 2023 Wiley-VCH GmbH.

JTD Keywords: electronics, fabrication, intelligent multifunction, monolithic patterns, signal monitoring and processing, wearable devices, Gold nanowires, Intelligent multifunction, Intraocular-pressure, Monolithic patterns, Signal monitoring and processing, Wearable devices

We report a simple approach to fabricate free-standing perforated 2D nanomembranes hosting well-ordered 1D metallic nanostructures to obtain hybrid materials with nanostructured surfaces for flexible electronics. Nanomembranes are formed by alternatively depositing perforated poly(lactic acid) (PLA) and poly(3,4-ethylenedioxythiophene) layers. Copper metallic nanowires (NWs) were incorporated into the nanoperforations of the top PLA layer by electrodeposition and further coated with silver via a transmetallation reaction. The combination of 2D polymeric nanomembranes and aligned 1D metallic NWs allows merging the flexibility and conformability of the ultrathin soft polymeric nanomembranes with the good electrical properties of metals for biointegrated electronic devices. Thus, we were able to tailor the nanomembrane surface chemistry as it was corroborated by SEM, EDX, XPS, CV, EIS and contact angle. The obtained hybrid nanomembranes were flexible and conformable showing sensing capacity towards H2O2 with good linear concentration range (0.35–10 mM), sensitivity (120 µA cm?2 mM?1) and limit of detection (7 ?m). Moreover, the membranes showed good stability, reproducibility and selectivity towards H2O2.

JTD Keywords: biointegrated sensors, designs, electronics, fabrication, free-standing films, h2o2, metallic nanowires, nanoparticles, nanowires, sensor, skin, Hydrogen-peroxide, Perforated nanomembranes

The intestine is a complex tissue with a characteristic three-dimensional (3D) crypt-villus architecture, which plays a key role in the intestinal function. This function is also regulated by the intestinal stroma that actively supports the intestinal epithelium, maintaining the homeostasis of the tissue. Efforts to account for the 3D complex structure of the intestinal tissue have been focused mainly in mimicking the epithelial barrier, while solutions to include the stromal compartment are scarce and unpractical to be used in routine experiments. Here we demonstrate that by employing an optimized bioink formulation and the suitable printing parameters it is possible to produce fibroblast-laden crypt-villus structures by means of digital light projection stereolithography (DLP-SLA). This process provides excellent cell viability, accurate spatial resolution, and high printing throughput, resulting in a robust biofabrication approach that yields functional gut mucosa tissues compatible with conventional testing techniques.Copyright © 2023 Elsevier B.V. All rights reserved.

JTD Keywords: 3d microstructure, barrier, cells, epithelial-stromal interactions, gelma-pegda soft hydrogels, growth, hydrogel, intestinal mucosa model, methacrylamide, microfabrication, proliferation, scaffold, stereolithography, 3d bioprinting, 3d microstructure, Epithelial-stromal interactions, Fibroblasts, Gelma-pegda soft hydrogels, Intestinal mucosa model

Electrochemically responsive hydrogel networks have been obtained usin g printable inks made of a biopolymer, alginate (Alg), and an inorganic 2D material , MXene (titaniu m carbide, Ti3C2Tx) nanosheets. While MXene offers an electrically conductive pathway for electron transfer and Alg provides an interconnected framework for ion diffusion, the printed nanocomposite results, after gelation, in an extended active interface for redox reactions, being an ideal framework to design and construct flexible devices for biomedical applications. In this work, after characterization, we demonstrate that hydrogels obtained by cross-linking printed Alg /MXene inks exhibit great potential for bioelectronics. More specifically, we prove that flexible Alg/MXene hydrogels act as self-supported electroactive electrodes for the electrochemical detection of bioanalytes, such as dopamine, with a performance similar to that achieved using more sophisticated electrodes, as for example those containing conducting poly-mers and electrocatalytic gold nanoparticles. In addition, Alg/MXene hydrogels have been successfully used to regulate the release of a previously loaded broad spectrum antibiotic (chloramphenicol) by electrical stimulation.

JTD Keywords: 3d-printing, Biomedical application s, Composites, Conducting polymers, Drug release, Electroresponsive hydrogels, Fabrication, Hydrogels, Platform, Sensors, Strategy, Surface, Thin-film, Titanium carbide

JTD Keywords: Biofabrication, In vitro microenvironments

JTD Keywords: 3d printing, Biofabrication, Cardiac tissue engineering, Human heart, Human induced pluripotent stem cells

The past ten years have seen the rapid expansion of the field of biohybrid robotics. By combining engineered, synthetic components with living biological materials, new robotics solutions have been developed that harness the adaptability of living muscles, the sensitivity of living sensory cells, and even the computational abilities of living neurons. Biohybrid robotics has taken the popular and scientific media by storm with advances in the field, moving biohybrid robotics out of science fiction and into real science and engineering. So how did we get here, and where should the field of biohybrid robotics go next? In this perspective, we first provide the historical context of crucial subareas of biohybrid robotics by reviewing the past 10+ years of advances in microorganism-bots and sperm-bots, cyborgs, and tissue-based robots. We then present critical challenges facing the field and provide our perspectives on the vital future steps toward creating autonomous living machines.

JTD Keywords: biohybrid, cyborg, Biohybrid, Cell, Cyborg, Delivery, Fabrication, Flight, Insect, Living machines, Muscle activities, Muscular thin-films, Nanoparticles, Stimulation, Tissue

Organ-on-chip platforms combined with high-throughput sensing technology allow bridging gaps in information presented by 2D cultures modeled on static microphysiological systems. While these platforms do not aim to replicate whole organ systems with all physiological nuances, they try to mimic relevant structural, physiological, and functional features of organoids and tissues to best model disease and/or healthy states. The advent of this platform has not only challenged animal testing but has also presented the opportunity to acquire real-time, high-throughput data about the pathophysiology of disease progression by employing biosensors. Biosensors allow monitoring of the release of relevant biomarkers and metabolites as a result of physicochemical stress. It, therefore, helps conduct quick lead validation to achieve personalized medicine objectives. The organ-on-chip industry is currently embarking on an exponential growth trajectory. Multiple pharmaceutical and biotechnology companies are adopting this technology to enable quick patient-specific data acquisition at substantially low costs.

JTD Keywords: A-chip, Biosensor, Biosensors, Cancer, Cells, Culture, Disease models, Epithelial electrical-resistance, Hydrogel, Microfabrication, Microphysiological systems, Models, Niches, Organ-on-a-chips, Platform

Calcium phosphate cements (CPCs) are attractive synthetic bone grafts as they possess osteoconductive and osteoinductive properties. Their biomimetic synthesis grants them an intrinsic nano-and microporosity that resembles natural bone and is paramount for biological processes such as protein adhesion, which can later enhance cell adhesion. However, a main limitation of CPCs is the lack of macroporosity, which is crucial to allow cell colonization throughout the scaffold. Moreover, CPCs lack specific motifs to guide cell interactions through their membrane proteins. In this study, we explore a strategy targeting simultaneously both macroporosity and cell binding motifs within CPCs by the use of recombinant silk. A silk protein functionalized with the cell binding motif RGD serves as foaming template of CPCs to achieve biomimetic hydroxyapatite (HA) scaffolds with multiscale porosity. The synergies of RGD-motifs in the silk macroporous template and the biomimetic features of HA are explored for their potential to enhance mesenchymal stem cell adhesion, proliferation, migration and differentiation. Macroporous Silk-HA scaffolds improve initial cell adhesion compared to a macroporous HA in the absence of silk, and importantly, the presence of silk greatly enhances cell migration into the scaffold. Additionally, cell proliferation and osteogenic differentiation are achieved in the scaffolds.

JTD Keywords: Bioceramics, Bone, Bone regeneration, Composites, Degradation, Fabrication, Hydroxyapatite, Hydroxyapatite scaffolds, Injectability, Porosity, Recombinant spider silk, Rgd motifs, Silk, Stem-cells

Cells sense their environment through the cell membrane receptors. Interaction with extracellular ligands induces receptor clustering at the nanoscale, assembly of the signaling complexes in the cytosol and activation of downstream signaling pathways, regulating cell response. Nanoclusters of receptors can be further organized hierarchically in the cell membrane at the meso- and micro-levels to exert different biological functions. To study and guide cell response, cell culture substrates have been engineered with features that can interact with the cells at different scales, eliciting controlled cell responses. In particular, nanoscale features of 1-100 nm in size allow direct interaction between the material and single cell receptors and their nanoclusters. Since the first "contact guidance" experiments on parallel microstructures, many other studies followed with increasing feature resolution and biological complexity. Here we present an overview of the advances in the field summarizing the biological scenario, substrate fabrication techniques and applications, highlighting the most recent developments.Copyright © 2022 Casanellas, Samitier and Lagunas.

JTD Keywords: cell response, density, differentiation, lithography, micro, nanofabrication, nanopatterning, nanopatterns, nanoscale, nanotopography, organization, photolithography, Cell response, Nanofabrication, Nanopatterning, Nanotopography, Plasma-membrane, Receptor nanoclustering

Type 1 Diabetes results from autoimmune response elicited against β-cell antigens. Nowadays, insulin injections remain the leading therapeutic option. However, injection treatment fails to emulate the highly dynamic insulin release that β-cells provide. 3D cell-laden microspheres have been proposed during the last years as a major platform for bioengineering insulin-secreting constructs for tissue graft implantation and a model for in vitro drug screening platforms. Current microsphere fabrication technologies have several drawbacks: the need for an oil phase containing surfactants, diameter inconsistency of the microspheres, and high time-consuming processes. These technologies have widely used alginate for its rapid gelation, high processability, and low cost. However, its low biocompatible properties do not provide effective cell attachment. This study proposes a high-throughput methodology using a 3D bioprinter that employs an ECM-like microenvironment for effective cell-laden microsphere production to overcome these limitations. Crosslinking the resulting microspheres with tannic acid prevents collagenase degradation and enhances spherical structural consistency while allowing the diffusion of nutrients and oxygen. The approach allows customization of microsphere diameter with extremely low variability. In conclusion, a novel bio-printing procedure is developed to fabricate large amounts of reproducible microspheres capable of secreting insulin in response to extracellular glucose stimuli.© 2022 The Authors. Advanced Materials Technologies published by Wiley‐VCH GmbH.

JTD Keywords: 3d bioprinter, beta-cell, biomaterial, collagen, encapsulation, mechanics, microspheres, survival, 3d bioprinter, ?-cell, Advanced material technologies, Biocompatibility, Cell encapsulations, Cells, Collagen, Cross-linking, Cytology, Drug delivery, Encapsulation, Fabrication, Flavonoids, Gelation, In-vitro, Insulin injections, Insulin release, Microspheres, Tannic acid, Tannins, Throughput, Tissue grafts, Type 1 diabetes, Β‐cell

Technologies to cryogenically preserve (a.k.a. cryopreserve) living tissue, cell lines and primary cells have matured greatly for both clinicians and researchers since their first demonstration in the 1950s and are widely used in storage and transport applications. Currently, however, there remains an absence of viable cryopreservation and thawing methods for bioengineered, three-dimensional (3D) cell models, including patients' samples. As a first step towards addressing this gap, we demonstrate a viable protocol for spheroid cryopreservation and survival based on a 3D carboxymethyl cellulose scaffold and precise conditions for freezing and thawing. The protocol is tested using hepatocytes, for which the scaffold provides both the 3D structure for cells to self-arrange into spheroids and to support cells during freezing for optimal post-thaw viability. Cell viability after thawing is improved compared to conventional pellet models where cells settle under gravity to form a pseudo-tissue before freezing. The technique may advance cryobiology and other applications that demand high-integrity transport of pre-assembled 3D models (from cell lines and in future cells from patients) between facilities, for example between medical practice, research and testing facilities.

JTD Keywords: 3d cell culture, biofabrication, biomaterials, carboxymethyl cellulose, cryopreservation, hepatocytes, 3d cell culture, Biofabrication, Biomaterials, Carboxymethyl cellulose, Cell culture techniques, three dimensional, Cell survival, Cryopreservation, Freezing, Hepatocytes, Humans, Prevention, Scaffolds, Spheroids

Biomolecular gradients are widely present in multiple biological processes. Historically they were reproduced in vitro by using micropipettes, Boyden and Zigmond chambers, or hydrogels. Despite the great utility of these setups in the study of gradient-related problems such as chemotaxis, they face limitations when trying to translate more complex in vivo-like scenarios to in vitro systems. In the last 20 years, the advances in manufacturing of micromechanical systems (MEMS) had opened the possibility of applying this technology to biology (BioMEMS). In particular, microfluidics has proven extremely efficient in setting-up biomolecular gradients which are stable, controllable, reproducible and at length scales that are relevant to cells. In this chapter, we give an overview of different methods to generate molecular gradients using microfluidics, then we discuss the different steps of the pipeline to fabricate a gradient generator microfluidic device, and at the end, we show an application example of the fabrication of a microfluidic device that can be used to generate a surface-bound biomolecular gradient.© 2022. The Author(s), under exclusive license to Springer Nature Switzerland AG.

JTD Keywords: biomems, gradient, microfluidics, model, nanotechnology, proteins, Biomems, Gradient, Mechanisms, Microfabrication, Microfluidics, Nanotechnology

The presence of organic pollutants in the environment is a global threat to human health and ecosystems due to their bioaccumulation and long-term persistence. Hereby a micromotor-in-sponge concept is presented that aims not only at pollutant removal, but towards an efficient in situ degradation by exploiting the synergy between the sponge hydrophobic nature and the rapid pollutant degradation promoted by the cobalt-ferrite (CFO) micromotors embedded at the sponge's core. Such a platform allows the use of extremely low fuel concentration (0.13% H2 O2 ), as well as its reusability and easy recovery. Moreover, the authors demonstrate an efficient multicycle pollutant degradation and treatment of large volumes (1 L in 15 min) by using multiple sponges. Such a fast degradation process is due to the CFO bubble-propulsion motion mechanism, which induces both an enhanced fluid mixing within the sponge and an outward flow that allows a rapid fluid exchange. Also, the magnetic control of the system is demonstrated, guiding the sponge position during the degradation process. The micromotor-in-sponge configuration can be extrapolated to other catalytic micromotors, establishing an alternative platform for an easier implementation and recovery of micromotors in real environmental applications.© 2022 Wiley-VCH GmbH.

JTD Keywords: effective removal, fabrication, microbots, microjets, organic pollutants, propelled micromotors, self-propelled micromotors, sponges, water treatment, Oil-water separation, Organic pollutants, Water treatment

JTD Keywords: augmentation, calcium-phosphate, expansion, fabrication, hydroxyapatite, made artificial bones, osteogenesis, reconstruction, regeneration, 3-d printing, 3d printers, 3d printing, 3d-printing, Abstracting, Additives, Biomaterial, Bone, Bone regeneration, Bone substitution, Bone tissue engineering, Ceramic, Ceramics, Clinic, Controlled drug delivery, Personalized medicines, Surgical planning, Targeted drug delivery, Three-dimensional-printing, Tricalcium phosphate scaffolds

3D printing is a competitive manufacturing technology, which has opened up new possibilities for the fabrication of complex ceramic structures and customised parts. Extrusion-based technologies, also known as direct ink writing (DIW) or robocasting, are amongst the most used for ceramic materials. In them, the rheological properties of the ink play a crucial role, determining both the extrudability of the paste and the shape fidelity of the printed parts. However, comprehensive rheological studies of printable ceramic inks are scarce and may be difficult to understand for non-specialists. The aim of this review is to provide an overview of the main types of ceramic ink formulations developed for DIW and a detailed description of the more relevant rheological tests for assessing the printability of ceramic pastes. Moreover, the key rheological parameters are identified and linked to printability aspects, including the values reported in the literature for different ink compositions.

JTD Keywords: 3-dimensional structures, behavior, deposition, direct ink writing, freeform fabrication, gelation, glass scaffolds, mechanical-properties, printability, rheology, robocasting, suspensions, 3d printing, Direct ink writing, Phosphate scaffolds, Printability, Rheology, Robocasting

JTD Keywords: biocompatibility, bioresorbable stents, degradation, mechanical-properties, poly(epsilon-caprolactone), poly-l-lactic acid, polylactide, radiopacity, thermogel, x-ray imaging, Barium sulfate, Biocompatibility, Bioresorbable, Bioresorbable scaffolds, Bioresorbable stent, Bioresorbable stents, Blood vessels, Computerized tomography, Controlled drug delivery, Coronary heart disease, Direct-writing, Endothelial cells, Fabrication strategies, Injection molding, Lactic acid, Poly-l-lactic acid, Poly-l-lactic acids, Radiopacity, Scaffolds (biology), Solvent cast, Solvent-cast direct-writing, Solvents, Stents, Struts, Sulfur compounds, Targeted drug delivery, X-ray imaging

The creation of cardiac tissue models for preclinical testing is still a non-solved problem in drug discovery, due to the limitations related to thein vitroreplication of cardiac tissue complexity. Among these limitations, the difficulty of mimicking the functional properties of the myocardium due to the immaturity of the used cells hampers the obtention of reliable results that could be translated into human patients.In vivomodels are the current gold standard to test new treatments, although it is widely acknowledged that the used animals are unable to fully recapitulate human physiology, which often leads to failures during clinical trials. In the present work, we present a microfluidic platform that aims to provide a range of signaling cues to immature cardiac cells to drive them towards an adult phenotype. The device combines topographical electrospun nanofibers with electrical stimulation in a microfabricated system. We validated our platform using a co-culture of neonatal mouse cardiomyocytes and cardiac fibroblasts, showing that it allows us to control the degree of anisotropy of the cardiac tissue inside the microdevice in a cost-effective way. Moreover, a 3D computational model of the electrical field was created and validated to demonstrate that our platform is able to closely match the distribution obtained with the gold standard (planar electrode technology) using inexpensive rod-shaped biocompatible stainless-steel electrodes. The functionality of the electrical stimulation was shown to induce a higher expression of the tight junction protein Cx-43, as well as the upregulation of several key genes involved in conductive and structural cardiac properties. These results validate our platform as a powerful tool for the tissue engineering community due to its low cost, high imaging compatibility, versatility, and high-throughput configuration capabilities.

JTD Keywords: bioreactor, cardiac tissue engineering, cardiomyocytes, electrospinning, fabrication, fibroblasts, heart-on-a-chip, heart-tissue, in vitro models, myocardium, orientation, platform, scaffolds, Cardiac tissue engineering, Electrospinning, Field stimulation, Heart-on-a-chip, In vitro models, Microphysiological system

© BME-PT. Ultrasound micromolding (USM) preparation of hybrid scaffolds based on polylactide (PLA) and hydroxyapatite (HAp) particles has been evaluated. PLA was stable under the applied ultrasound source since a minimum degradation was detected. Porous materials were achieved using polyethylene glycol (PEG) and NaCl salts to the initial PLA and the subsequent leaching of the micromolded specimens. To avoid cavitation and decomposition problems during micromolding, it was necessary to use HAp free of typical synthesis impurities like carbonate and nitrate compounds. Compact PLA/HAp pieces allowed a maximum HAp load of 60 wt%, while porous specimens could be obtained with a maximum load of 38 wt%. Physical characterization of new scaffolds was performed by X-ray diffraction, spectroscopic and calorimetric techniques, stress-strain tests and contact angle measurements. Results indicated that a degree of porosity of 35% and relatively good mechanical properties could be achieved (i.e., 580 MPa, 4%, and 15.6 MPa for the Young modulus, elongation at break, and tensile strength, respectively). Scaffolds showed the positive effect of HAp and porosity on cell proliferation; this latter was 40% higher than that detected for non-porous PLA specimens.

JTD Keywords: apatite, conformation, fabrication, hydroxyapatite, micropieces, polymers, porous scaffolds, proliferation, tissue, ultrasound micromolding, vibration, Composite scaffolds, Hydroxyapatite, Micropieces, Porous scaffolds, Processing technologies, Ultrasound micromolding

Bioinspired hybrid soft robots that combine living and synthetic components are an emerging field in the development of advanced actuators and other robotic platforms (i.e., swimmers, crawlers, and walkers). The integration of biological components offers unique characteristics that artificial materials cannot precisely replicate, such as adaptability and response to external stimuli. Here, we present a skeletal muscle–based swimming biobot with a three-dimensional (3D)–printed serpentine spring skeleton that provides mechanical integrity and self-stimulation during the cell maturation process. The restoring force inherent to the spring system allows a dynamic skeleton compliance upon spontaneous muscle contraction, leading to a cyclic mechanical stimulation process that improves the muscle force output without external stimuli. Optimization of the 3D-printed skeletons is carried out by studying the geometrical stiffnesses of different designs via finite element analysis. Upon electrical actuation of the muscle tissue, two types of motion mechanisms are experimentally observed: directional swimming when the biobot is at the liquid-air interface and coasting motion when it is near the bottom surface. The integrated compliant skeleton provides both the mechanical self-stimulation and the required asymmetry for directional motion, displaying its maximum velocity at 5 hertz (800 micrometers per second, 3 body lengths per second). This skeletal muscle–based biohybrid swimmer attains speeds comparable with those of cardiac-based biohybrid robots and outperforms other muscle-based swimmers. The integration of serpentine-like structures in hybrid robotic systems allows self-stimulation processes that could lead to higher force outputs in current and future biomimetic robotic platforms. Copyright © 2021 The Authors, some rights reserved;

JTD Keywords: actuators, design, fabrication, mechanics, mems, myotubes, platform, tissue, 3d printers, Agricultural robots, Biological components, Biomimetic processes, Electrical actuation, Geometrical stiffness, Intelligent robots, Liquefied gases, Liquid-air interface, Mechanical integrity, Mechanical stimulation, Muscle, Muscle contractions, Phase interfaces, Robotics, Serpentine, Springs (components), Threedimensional (3-d)

Tissue barriers play a crucial role in human physiology by establishing tissue compartmentalization and regulating organ homeostasis. At the interface between the extracellular matrix (ECM) and flowing fluids, epithelial and endothelial barriers are responsible for solute and gas exchange. In the past decade, microfluidic technologies and organ-on-chip devices became popular as in vitro models able to recapitulate these biological barriers. However, in conventional microfluidic devices, cell barriers are primarily grown on hard polymeric membranes within polydimethylsiloxane (PDMS) channels that do not mimic the cell-ECM interactions nor allow the incorporation of other cellular compartments such as stromal tissue or vascular structures. To develop models that accurately account for the different cellular and acellular compartments of tissue barriers, researchers have integrated hydrogels into microfluidic setups for tissue barrier-on-chips, either as cell substrates inside the chip, or as self-contained devices. These biomaterials provide the soft mechanical properties of tissue barriers and allow the embedding of stromal cells. Combining hydrogels with microfluidics technology provides unique opportunities to better recreate in vitro the tissue barrier models including the cellular components and the functionality of the in vivo tissues. Such platforms have the potential of greatly improving the predictive capacities of the in vitro systems in applications such as drug development, or disease modeling. Nevertheless, their development is not without challenges in their microfabrication. In this review, we will discuss the recent advances driving the fabrication of hydrogel microfluidic platforms and their applications in multiple tissue barrier models.

JTD Keywords: hydrogel, microfabrication, microfluidics, organ-on-chip, tissue barrier, Hydrogel, Microfabrication, Microfluidics, Organ-on-chip, Tissue barrier

Background Small cardiac tissue engineering constructs show promise for limiting post-infarct sequelae in animal models. This study sought to scale-up a 2-cm2 preclinical construct into a human-size advanced therapy medicinal product (ATMP; PeriCord), and to test it in a first-in-human implantation. Methods The PeriCord is a clinical-size (12–16 cm2) decellularised pericardial matrix colonised with human viable Wharton's jelly-derived mesenchymal stromal cells (WJ-MSCs). WJ-MSCs expanded following good manufacturing practices (GMP) met safety and quality standards regarding the number of cumulative population doublings, genomic stability, and sterility. Human decellularised pericardial scaffolds were tested for DNA content, matrix stiffness, pore size, and absence of microbiological growth. Findings PeriCord implantation was surgically performed on a large non-revascularisable scar in the inferior wall of a 63-year-old male patient. Coronary artery bypass grafting was concomitantly performed in the non-infarcted area. At implantation, the 16-cm2 pericardial scaffold contained 12·5 × 106 viable WJ-MSCs (85·4% cell viability; <0·51 endotoxin units (EU)/mL). Intraoperative PeriCord delivery was expeditious, and secured with surgical glue. The post-operative course showed non-adverse reaction to the PeriCord, without requiring host immunosuppression. The three-month clinical follow-up was uneventful, and three-month cardiac magnetic resonance imaging showed ~9% reduction in scar mass in the treated area. Interpretation This preliminary report describes the development of a scalable clinical-size allogeneic PeriCord cardiac bioimplant, and its first-in-human implantation. Funding La Marató de TV3 Foundation, Government of Catalonia, Catalan Society of Cardiology, “La Caixa” Banking Foundation, Spanish Ministry of Science, Innovation and Universities, Institute of Health Carlos III, and the European Regional Development Fund.

JTD Keywords: Advanced therapy medicinal product (ATMP), Biofabrication, Cardiac tissue engineering, Myocardial infarction, Scaffold, Wharton's jelly-derived mesenchymal stromal cells (WJ-MSCs)

The introduction of 3D bioprinting to fabricate living constructs with tailored architecture has provided a new paradigm for biofabrication, with the potential to overcome several drawbacks of conventional scaffold-based tissue regeneration strategies. Hydrogel-based materials are suitable candidates regarding cell biocompatibility but often display poor mechanical properties. Self-assembling peptides are a promising source of biomaterials to be used as 3D scaffolds based on their similarity to extracellular matrices (structurally and mechanically). In this study, an advanced bioink for biofabrication is presented based on the optimization of a RAD16-I-based biomaterial. The strategy followed to build 3D predefined structures by 3D printing is based on an enhancement of bioink viscosity by adding methylcellulose (MC) to a RAD16-I solution. The resultant constructs display high shape fidelity and stability and embedded human mesenchymal stem cells present high viability after 7 days of culture. Moreover, cells are also able to differentiate to the adipogenic lineage, suggesting the suitability of this novel biomaterial for soft tissue engineering applications.

JTD Keywords: 3D bioprinting, Biofabrication, Bioinks, Self-assembling peptides, Tissue engineering

Emerging nanobiotechnologies can offer solutions to the current and future challenges in medicine. By covering topics from regenerative medicine, tissue engineering, drug delivery, bionanofabrication, and molecular biorecognition, this Special Issue aims to provide an update on the trends in nanomedicine and drug delivery using biomimetic approaches, and the development of novel biologically inspired devices for the safe and effective diagnosis, prevention, and treatment of disease.

JTD Keywords: Bioinspired nanotechnologies, Bionanofabrication, Bio-nano measurement and microscopy, Nanomaterials for biological and medical applications, Nanoassemblies, Nanostructured surfaces, Drug delivery, Nanobioelectronics, Integrated systems/nanobiosensors, Nanotoxicology, Graphene-based applications

Epithelial tissues are composed of layers of tightly connected cells shaped into complex three-dimensional (3D) structures such as cysts, tubules, or invaginations. These complex 3D structures are important for organ-specific functions and often create biochemical gradients that guide cell positioning and compartmentalization within the organ. One of the main functions of epithelia is to act as physical barriers that protect the underlying tissues from external insults. In vitro, epithelial barriers are usually mimicked by oversimplified models based on cell lines grown as monolayers on flat surfaces. While useful to answer certain questions, these models cannot fully capture the in vivo organ physiology and often yield poor predictions. In order to progress further in basic and translational research, disease modeling, drug discovery, and regenerative medicine, it is essential to advance the development of new in vitro predictive models of epithelial tissues that are capable of representing the in vivo-like structures and organ functionality more accurately. Here, we review current strategies for obtaining biomimetic systems in the form of advanced in vitro models that allow for more reliable and safer preclinical tests. The current state of the art and potential applications of self-organized cell-based systems, organ-on-a-chip devices that incorporate sensors and monitoring capabilities, as well as microfabrication techniques including bioprinting and photolithography, are discussed. These techniques could be combined to help provide highly predictive drug tests for patient-specific conditions in the near future.

JTD Keywords: 3D cell culture models, Biofabrication, Disease modeling, Drug screening, Epithelial barriers, Microengineered tissues, Organ-on-a-chip, Organoids

Organ biofabrication is a potential future alternative for obtaining viable organs for transplantation. Achieving intact scaffolds to be recellularized is a key step in lung bioengineering. Perfusion of decellularizing media through the pulmonary artery has shown to be effective. How vascular perfusion pressure and flow vary throughout lung decellularization, which is not well known, is important for optimizing the process (minimizing time) while ensuring scaffold integrity (no barotrauma). This work was aimed at characterizing the pressure/flow relationship at the pulmonary vasculature and at how effective vascular resistance depends on pressure- and flow-controlled variables when applying different methods of media perfusion for lung decellularization. Lungs from 43 healthy mice (C57BL/6; 7-8 weeks old) were investigated. After excision and tracheal cannulation, lungs were inflated at 10cmH2O airway pressure and subjected to conventional decellularization with a solution of 1% sodium dodecyl sulfate (SDS). Pressure (PPA) and flow (V'PA) at the pulmonary artery were continuously measured. Decellularization media was perfused through the pulmonary artery: (a) at constant PPA=20cmH2O or (b) at constant V'PA=0.5 and 0.2ml/min. Effective vascular resistance was computed as Rv=PPA/V'PA. Rv (in cmH2O/(ml/min)); mean±SE) considerably varied throughout lung decellularization, particularly for pressure-controlled perfusion (from 29.1±3.0 in baseline to a maximum of 664.1±164.3 (p<0.05), as compared with flow-controlled perfusion (from 49.9±3.3 and 79.5±5.1 in baseline to a maximum of 114.4±13.9 and 211.7±70.5 (p<0.05, both), for V'PA of 0.5 and 0.2ml/min respectively. Most of the media infused to the pulmonary artery throughout decellularization circulated to the airways compartment across the alveolar-capillary membrane. This study shows that monitoring perfusion mechanics throughout decellularization provides information relevant for optimizing the process time while ensuring that vascular pressure is kept within a safety range to preserve the organ scaffold integrity.

JTD Keywords: Acellular lung, Fluid mechanics, Lung bioengineering, Lung scaffold, Organ biofabrication, Tissue engineering, Vascular resistance

Here we have developed a simple method for the fabrication of disposable implantable all-solid-state ion-selective electrodes (ISE) in an array format without using complex fabrication equipment or clean room facilities. The electrodes were designed in a needle shape instead of planar electrodes for a full contact with the tissue. The needle-shape platform comprises 12 metallic pins which were functionalized with conductive inks and ISE membranes. The modified microelectrodes were characterized with cyclic voltammetry, scanning electron microscope (SEM), and optical interferometry. The surface area and roughness factor of each microelectrode were determined and reproducible values were obtained for all the microelectrodes on the array. In this work, the microelectrodes were modified with membranes for the detection of pH and nitrate ions to prove the reliability of the fabricated sensor array platform adapted to an endoscope.

JTD Keywords: Chemical sensors, Cyclic voltammetry, Electrochemistry, Endoscopy, Fabrication, Implants (surgical), Microelectrodes, Needles, Nitrates, Scanning electron microscopy, Biomedicine, Fabricated sensors, Fabrication equipment, Implantable devices, Implantable sensors, Optical interferometry, Planar electrode, Roughness factor, Ion selective electrodes

The fabrication of hierarchical and bioactive self-supporting membranes, which integrate physical and biomolecular elements, using a single-step process that combines molecular self-assembly with soft lithography is reported. A positively charged multidomain peptide (with or without the cell-adhesive sequence arginine-glycine-aspartic acid-serine (RGDS)) self-assembles with hyaluronic acid (HA), an anionic biopolymer. Optimization of the assembling conditions enables the realization of membranes with well-controlled and easily tunable features at multiple size scales including peptide sequence, building-block co-assembly, membrane thickness, bioactive epitope availability, and topographical pattern morphology. Membrane structure, morphology, and bioactivity are investigated according to temperature, assembly time, and variations in the experimental setup. Furthermore, to evaluate the physical and biomolecular signaling of the self-assembled microfabricated membranes, rat mesenchymal stem cells are cultured on membranes exhibiting various densities of RGDS and different topographical patterns. Cell adhesion, spreading, and morphology are significantly affected by the surface topographical patterns and the different concentrations of RGDS. The versatility of the combined bottom-up and top-down fabrication processes described may permit the development of hierarchical macrostructures with precise biomolecular and physical properties and the opportunity to fine tune them with spatiotemporal control.

JTD Keywords: Membrane scaffolds, Mesenchymal stem cells, Microfabrication, Self-assembly, Topography

Cell growth and differentiation are critically dependent upon matrix rigidity, yet many aspects of the cellular rigidity-sensing mechanism are not understood. Here, we analyze matrix forces after initial cell-matrix contact, when early rigidity-sensing events occur, using a series of elastomeric pillar arrays with dimensions extending to the submicron scale (2, 1, and 0.5 μm in diameter covering a range of stiffnesses). We observe that the cellular response is fundamentally different on micron-scale and submicron pillars. On 2-μm diameter pillars, adhesions form at the pillar periphery, forces are directed toward the center of the cell, and a constant maximum force is applied independent of stiffness. On 0.5-μm diameter pillars, adhesions form on the pillar tops, and local contractions between neighboring pillars are observed with a maximum displacement of ∼60 nm, independent of stiffness. Because mutants in rigidity sensing show no detectable displacement on 0.5-μm diameter pillars, there is a correlation between local contractions to 60 nm and rigidity sensing. Localization of myosin between submicron pillars demonstrates that submicron scale myosin filaments can cause these local contractions. Finally, submicron pillars can capture many details of cellular force generation that are missed on larger pillars and more closely mimic continuous surfaces.

JTD Keywords: Cell mechanics, Mechanotransduction, Nanofabrication

A method for the simultaneous (bio)chemical and topographical patterning of enclosed structures in poly(dimethyl siloxane) (PDMS) is presented. The simultaneous chemical and topography transference uses a water-soluble chitosan sacrificial mold to impart a predefined pattern with micrometric accuracy to a PDMS replica. The method is compared to conventional soft-lithography techniques on planar surfaces. Its functionality is demonstrated by the transference of streptavidin directly to the surface of the three-dimensional PDMS structures as well as indirectly using streptavidin-loaded latex nanoparticles. The streptavidin immobilized on the PDMS is tested for bioactivity by coupling with fluorescently labeled biotin. This proves that the streptavidin is immobilized on the PDMS surface, not in the bulk of the polymer, and is therefore accessible for use as signaling/binding element in micro and bioengineering. The use of a biocompatible polymer and processes enables the technique to be used for the chemical patterning of tissue constructions.

JTD Keywords: Biotechnology, Chitosan, Microfabrication, MEMs, Soft lithography

This article describes a simple method for the construction of a universal surface chemical gradient platform based on the biotin streptavidin model. In this approach, surface chemical gradients were prepared in poly(methyl methacrylate) (PM MA), a biocompatible polymer, by a controlled hydrolysis procedure. The physicochemical properties of the resulting modified surfaces were extensively characterized. Chemical analysis carried out via time-of-flight secondary ion mass spectrometry (ToRSIMS) and X-ray photoelectron spectroscopy (XPS) showed the formation of a smooth, highly controllable carboxylic acid gradient of increasing concentration along the sample surface. Atomic force microscopy (AFM) and contact angle (CA) results indicate that, in contrast with most of the chemical gradient methods published in the literature, the chemical modification of the polymer surface barely affects its physical properties. The introduction of carboxylic acid functionality along the surface was then used for biomolecule anchoring. For this purpose, the surface was activated and derivatized first with biotin and finally with streptavidin (SA V) in a directed orientation fashion. The SAV gradient was qualitatively assessed by fluorescence microscopy analysis and quantified by surface plasmon resonance (SPR) in order to establish a quantitative relationship between SAV surface densities and the surface location. The usefulness of the fabrication method described for biological applications was tested by immobilizing biotinylated bradykinin onto the SAV gradient. This proof-of-concept application shows the effectiveness of the concentration range of the gradient because the effects of bradykinin on cell morphology were observed to increase gradually with increasing drug concentrations. The intrinsic characteristics of the fabricated gradient platform (absence of physicochemical modifications other than those due to the biomolecules included) allow us to attribute cell behavior unequivocally to the biomolecule surface density changes.

JTD Keywords: Wettability gradient, Polyethylene surface, Combinatorial, Immobilization, Biomaterials, Fabrication, Deposition, Bradykinin, Monolayers, Discharge

The shape and dimensions of an atomic force microscope tip are crucial factors to obtain high resolution images at the nanoscale. When measuring samples with narrow trenches, inclined sidewalls near 90 or nanoscaled structures, standard silicon atomic force microscopy (AFM) tips do not provide satisfactory results. We have combined deep reactive ion etching (DRIE) and focused ion beam (FIB) lithography techniques in order to produce probes with sharp rocket-shaped silicon AFM tips for high resolution imaging. The cantilevers were shaped and the bulk micromachining was performed using the same DRIE equipment. To improve the tip aspect ratio we used FIB nanolithography technique. The tips were tested on narrow silicon trenches and over biological samples showing a better resolution when compared with standard AFM tips, which enables nanocharacterization and nanometrology of high-aspect-ratio structures and nanoscaled biological elements to be completed, and provides an alternative to commercial high aspect ratio AFM tips.

JTD Keywords: Atomic-Force Microscope, Carbon nanotube tips, Probes, Roughness, Cells, Microfabrication, Calibration, Surfaces

Biological patterned surfaces having sub-micron scale resolution are of great importance in many fields of life science and biomedicine. Different techniques have been proposed for surface patterning at the nanoscale. However, most of them present some limitations regarding the patterned area size or are time-consuming. Micro/nanocontact printing is the most representative soft lithography-based technique for surface patterning at the nanoscale. Unfortunately, conventional micro/nanocontact printing also suffers from problems such as diffusion and stamp collapsing that limit pattern resolution. To overcome these problems, a simple way of patterning thiols under liquid media using submerged nanocontact printing (SnCP) over large areas (similar to cm(2)) achieving nanosize resolution is presented. The technique is also low cost and any special equipment neither laboratory conditions are required. Nanostructured poly(dimethyl siloxane) stamps are replicated from commercially available digital video disks. SnCP is used to stamp patterns of 200 nm 1-octadecanethiol lines in liquid media, avoiding ink diffusion and stamp collapsing, over large areas on gold substrates compared with conventional procedures. Atomic force microscopy measurements reveal that the patterns have been successfully transferred with high fidelity. This is an easy, direct, effective and low cost methodology for molecule patterning immobilization which is of interest in those areas that require nanoscale structures over large areas, such as tissue engineering or biosensor applications.

JTD Keywords: Submerged Nanocontact Printing, Replica Molding, Nanopatterning, Large Area, Dip-pen nanolithography, High-aspect-ratio, Soft lithography, Submicronscale, Nanoimprint lithography, Thin-film, Surfaces, Fabrication, Proteins, Nanofabrication

Micro- and nanoscale protein patterns have been produced via a new contact printing method using a nanoimprint lithography apparatus. The main novelty of the technique is the use of poly(methyl methacrylate) (PMMA) instead of the commonly used poly(dimethylsiloxane) (PDMS) stamps. This avoids printing problems due to roof collapse, which limits the usable aspect ratio in microcontact printing to 10:1. The rigidity of the PMMA allows protein patterning using stamps with very high aspect ratios, up to 300 in this case. Conformal contact between the stamp and the substrate is achieved because of the homogeneous pressure applied via the nanoimprint lithography instrument, and it has allowed us to print lines of protein similar to 150 nm wide, at a 400 nm period. This technique, therefore, provides an excellent method for the direct printing of high-density sub-micrometer scale patterns, or, alternatively, micro-/nanopatterns spaced at large distances. The controlled production of these protein patterns is a key factor in biomedical applications such as cell-surface interaction experiments and tissue engineering.

JTD Keywords: Soft lithography, Cell-adhesion, Microstructures, Fabrication, Stability, Patterns

-----

JTD Keywords: Self-assembled monolayers, High-aspect-ratio, Dip-pen nanolithography, Langmuir-blodgett-films, Conducting polymer, Enzymes, Microstructures, Immunosensors, Fabrication, Stability