Publications

Endothelium, the lining in this blood vessel, orchestrates three main critical functions such as protecting blood components, modulating of hemostasis by secreting various inhibitors, and directing clot digestion (fibrinolysis) by activating tissue plasminogen activator. No other surface can perform these tasks; thus, the contact of blood and blood-contacting medical devices inevitably leads to the activation of coagulation, often causing device failure, and thromboembolic complications. This perspective, first, discusses the biological mechanisms of activation of coagulation and highlights the efforts of advanced coatings to recapitulate one characteristic of endothelium, hereafter single functions of endothelium and noting necessity of the synergistic integration of its three main functions. Subsequently, it is emphasized that to overcome the challenges of blood compatibility an endothelium-mimicking system is needed, proposing a synergy of bottom-up synthetic biology, particularly synthetic cells, with passive- and bioactive surface coatings. Such integration holds promise for developing advanced biomaterials capable of recapitulating endothelial functions, thereby enhancing the hemocompatibility and performance of blood-contacting medical devices. The activation of coagulation on the surface of blood-contacting medical devices often leads to thromboembolic complications. A concept for the next generation of hemocompatbile surfaces inspired by endothelium is proposed. This concept not only contribute to the fundamental understanding of hemocompatibility but also offer practical implications for the design and development of biomedical devices with enhanced biocompatibility and functionality. image

JTD Keywords: Antifouling coatings, Antifouling polymer brushes, Coagulation-factor-xii, Endothelium-inspired, Hemocompatibility, Hemocompatible surface coatings, Heparin-induced thrombocytopenia, Nitric-oxide release, Of-the-art, Peptide macrocycle inhibitor, Plasma contact system, Protein-adsorption, Self-assembled monolayers, Surface modificatio, Synthetic endotheliu

Factor XII (FXII) is a zymogen present in blood that tends to adsorb onto the surfaces of blood-contacting medical devices. Once adsorbed, it becomes activated, initiating a cascade of enzymatic reactions that lead to surface-induced coagulation. This process is characterized by multiple redundancies, making it extremely challenging to prevent clot formation and preserve the properties of the surface. In this study, a novel modulatory coating system based on C1-esterase inhibitor (C1INH) functionalized polymer brushes, which effectively regulates the activation of FXII is proposed. Using surface plasmon resonance it is demonstrated that this coating system effectively repels blood plasma proteins, including FXII, while exhibiting high activity against activated FXII and plasma kallikrein under physiological conditions. This unique property enables the modulation of FXII activation without interfering with the overall hemostasis process. Furthermore, through dynamic Chandler loop studies, it is shown that this coating significantly improves the hemocompatibility of polymeric surfaces commonly used in medical devices. By addressing the root cause of contact activation, the synergistic interplay between the antifouling polymer brushes and the modulatory C1INH is expected to lay the foundation to enhance the hemocompatibility of medical device surfaces.© 2023 The Authors. Macromolecular Bioscience published by Wiley-VCH GmbH.

JTD Keywords: adsorption, binding, c1-esterase-inhibitor, coatings, contact activation, factor-xii, fxii activation, hemocompatibility, hemocompatible surface modification, heparin, polymer brushes, system, thrombosis, Adsorption, Anticoagulation, Antifouling agent, Article, Beta-fxiia, Biocompatibility, Blood, Blood clotting, Blood clotting factor 12, Blood clotting factor 12a, Blood clotting factor 12a inhibitor, Blood coagulation, C1-esterase-inhibitor, Cell activation, Chemical activation, Coagulation, Coating (procedure), Complement component c1s inhibitor, Complement system, Controlled study, Dendrimers, Enzyme immobilization, Enzymes, Erythrocyte, Esters, Factor xii, Factor xii activation, Factor xiia, Fibrin deposition, Functional polymers, Fxii activation, Haemocompatibility, Hemocompatibility, Hemocompatible surface modification, Hemostasis, Heparin, Human, Hydrogel, Medical devices, Metabolism, Plasma kallikrein, Plasma protein, Plastic coatings, Platelet count, Polymer, Polymer brushes, Polymerization, Polymers, Property, Root cause, Surface plasmon resonance, Surface property, Surface reactions, Surface-modification, Thrombocyte adhesion, Β-fxiia

Anisotropy is an important cue for neural organization during morphogenesis and healing, contributing to the mechanical and functional properties of neural tissues. The ability to replicate such anisotropy in vitro holds great promise for the development of effective regeneration strategies. In this work, interfacial polyelectrolyte complexation (IPC) is applied to fabricate microfibers from charged ECM components without any chemical modification. Using flow-focusing microfluidics, collagen (Col) and glycosaminoglycans (GAGs), such as chondroitin sulfate (CS) or heparin (Hep), form Col/CS and Col/Hep interfacial complexes that coalesce as IPC microfibers. These fibers are flexible and absorb large amounts of water but remain stable under physiological conditions. At these conditions, the tensile strength of the assembled Col/GAG microfibers is similar to the strength of the neural tissue. The fibers are biocompatible and biofunctional; PC12 neural cells adhere and orient longitudinally to the fibers. Moreover, Col/CS microfibers promote the formation of neural processes. The results demonstrate that the microfluidic-assisted IPC complexation enables the assembly of ECM mimics by synergetic integration of anisotropic, chemical, and mechanical cues that boost the development of neural cells.

JTD Keywords: Cells, Chondroitin sulfate, Collagen, Fibers, Glycosaminoglycans, Heparin, Microfibers

Malaria is an infectious disease transmitted by mosquitos, whose control is hampered by drug resistance evolution in the causing agent, protist parasites of the genus Plasmodium, as well as by the resistance of the mosquito to insecticides. New approaches to fight this disease are, therefore, needed. Research into targeted drug delivery is expanding as this strategy increases treatment efficacies. Alternatively, targeting the parasite in humans, here we use single-chain polymer nanoparticles (SCNPs) to target the parasite at the ookinete stage, which is one of the stages in the mosquito. This nanocarrier system provides uniquely sized and monodispersed particles of 5-20 nm, via thiol-Michael addition. The conjugation of succinic anhydride to the SCNP surface provides negative surface charges that have been shown to increase the targeting ability of SCNPs to Plasmodium berghei ookinetes. The biodistribution of SCNPs in mosquitos was studied, showing the presence of SCNPs in mosquito midguts. The presented results demonstrate the potential of anionic SCNPs for the targeting of malaria parasites in mosquitos and may lead to progress in the fight against malaria.

JTD Keywords: antimalarial, atovaquone, carriers, delivery, drug-conjugate, heparin, intramolecular crosslinking, plasmodium berghei, therapy, thiol-michael addition, transmission, Atovaquone, Drug-conjugate, Intramolecular crosslinking, Plasmodium berghei, Plasmodium-falciparum, Single chain polymer nanoparticles, Thiol-michael addition

The rampant evolution of resistance in Plasmodium to all existing antimalarial drugs calls for the development of improved therapeutic compounds and of adequate targeted delivery strategies for them. Loading antimalarials in nanocarriers specifically targeted to the parasite will contribute to the administration of lower overall doses, with reduced side effects for the patient, and of higher local amounts to parasitized cells for an increased lethality toward the pathogen. Here, we report the development of dendronized hyperbranched polymers (DHPs), with capacity for antimalarial loading, that are coated with heparin for their specific targeting to red blood cells parasitized by Plasmodium falciparum. The resulting DHP-heparin complexes exhibit the intrinsic antimalarial activity of heparin, with an IC50 of ca. 400 nM, added to its specific targeting to P. falciparum-infected (vs noninfected) erythrocytes. DHP-heparin nanocarriers represent a potentially interesting contribution to the limited family of structures described so far for the loading and targeted delivery of current and future antimalarial compounds.© 2022 The Authors. Published by American Chemical Society.

JTD Keywords: carriers, drug-delivery, efficacy, heparin, malaria, mosquito, nanocarriers, parasite, plasmodium, targeted drug delivery, Dendritic polymers, Red-blood-cells

Innovative antimalarial strategies are urgently needed given the alarming evolution of resistance to every single drug developed against Plasmodium parasites. The sulfated glycosaminoglycan heparin has been delivered in membrane feeding assays together with Plasmodium berghei-infected blood to Anopheles stephensi mosquitoes. The transition between ookinete and oocyst pathogen stages in the mosquito has been studied in vivo through oocyst counting in dissected insect midguts, whereas ookinete interactions with heparin have been followed ex vivo by flow cytometry. Heparin interferes with the parasite’s ookinete–oocyst transition by binding ookinetes, but it does not affect fertilization. Hypersulfated heparin is a more efficient blocker of ookinete development than native heparin, significantly reducing the number of oocysts per midgut when offered to mosquitoes at 5 µg/mL in membrane feeding assays. Direct delivery of heparin to mosquitoes might represent a new antimalarial strategy of rapid implementation, since it would not require clinical trials for its immediate deployment.

JTD Keywords: Anopheles, Antimalarial drugs, Heparin, Malaria, Mosquito, Ookinete, Plasmodium, Transmission blocking

The immobilization of natural molecules on synthetic bone grafts stands as a strategy to enhance their biological interactions. During the early stages of healing, immune cells and osteoclasts (OC) modulate the inflammatory response and resorb the biomaterial, respectively. In this study, heparin, a naturally occurring molecule in the bone extracellular matrix, was covalently immobilized on biomimetic calcium‐deficient hydroxyapatite (CDHA). The effect of heparin‐functionalized CDHA on inflammation and osteoclastogenesis was investigated using primary human cells and compared with pristine CDHA and beta-tricalcium phosphate (β-TCP). Biomimetic substrates led to lower oxidative stresses by neutrophils and monocytes than sintered β-TCP, even though no further reduction was induced by the presence of heparin. In contrast, heparinized CDHA fostered osteoclastogenesis. Optical images of stained TRAP positive cells showed an earlier and higher presence of multinucleated cells, compatible with OC at 14 days, while pristine CDHA and β-TCP present OC at 21–28 days. Although no statistically significant differences were found in the OC activity, microscopy images evidenced early stages of degradation on heparinized CDHA, compatible with osteoclastic resorption. Overall, the results suggest that the functionalization with heparin fostered the formation and activity of OC, thus offering a promising strategy to integrate biomaterials in the bone remodelling cycle by increasing their OC-mediated resorption.

JTD Keywords: Biomaterial, Heparin, Hydroxyapatite, Inflammation, Osteoclastogenesis

Immune cells play a vital role in regulating bone dynamics. This has boosted the interest in developing biomaterials that can modulate both the immune and skeletal systems. In this study, calcium phosphates discs (i.e., beta-tricalcium phosphate, β-TCP) are functionalized with heparin to investigate the effects on immune and stem cell responses. The results show that the functionalized surfaces downregulate the release of hydrogen peroxide and proinflammatory cytokines (tumor necrosis factor alpha and interleukin 1 beta) from human monocytes and neutrophils, compared to nonfunctionalized discs. The macrophages show both elongated and round shapes on the two ceramic substrates, but the morphology of cells on heparinized β-TCP tends toward a higher elongation after 72 h. The heparinized substrates support rat mesenchymal stem cell (MSC) adhesion and proliferation, and anticipate the differentiation toward the osteoblastic lineage as compared to β-TCP and control. The coupling between the inflammatory response and osteogenesis is assessed by culturing MSCs with the macrophage supernatants. The downregulation of inflammation in contact with the heparinized substrates induces higher expression of bone-related markers by MSCs.

JTD Keywords: Calcium phosphates, Heparinization, Inflammation, Osteogenesis

Heparin is one of the oldest drugs, which nevertheless remains in widespread clinical use as an inhibitor of blood coagulation. The history of its identification a century ago unfolded amid one of the most fascinating scientific controversies turning around the distribution of credit for its discovery. The composition, purification and structure-function relationship of this naturally occurring glycosaminoglycan regarding its classical role as anticoagulant will be dealt with before proceeding to discuss its therapeutic potential in, among other, inflammatory and infectious disease, cancer treatment, cystic fibrosis and Alzheimer's disease. The first bibliographic reference hit using the words 'nanomedicine' and 'heparin' is as recent as 2008. Since then, nanomedical applications of heparin have experienced an exponential growth that will be discussed in detail, with particular emphasis on its antimalarial activity. Some of the most intriguing potential applications of heparin nanomedicines will be exposed, such as those contemplating the delivery of drugs to the mosquito stages of malaria parasites.

JTD Keywords: Anopheles, Antimalarial drugs, Heparin, Malaria, Mosquitoes, Nanomedicine, Nanotechnology, Plasmodium, Targeted drug delivery

JTD Keywords: Anopheles, Antimalarial drugs, Combination therapies, Heparin, Malaria, Mosquitoes, Nanomedicine, Nanotechnology, Plasmodium, Poly(amidoamine)s, Polymers, Targeted drug delivery

A simple method for constructing versatile ordered biotin/avidin arrays on UV-curable perfluoropolyethers (PFPEs) is presented. The goal is the realization of a versatile platform where any biotinylated biological ligands can be further linked to the underlying biotin/avidin array. To this end, microcontact arrayer and microcontact printing technologies were developed for photobiotin direct printing on PFPEs. As attested by fluorescence images, we demonstrate that this photoactive form of biotin is capable of grafting onto PFPEs surfaces during irradiation. Bioaffinity conjugation of the biotin/avidin system was subsequently exploited for further self-assembly avidin family proteins onto photobiotin arrays. The excellent fouling release PFPEs surface properties enable performing avidin assembly step simply by arrays incubation without PFPEs surface passivation or chemical modification to avoid unspecific biomolecule adsorption. Finally, as a proof of principle biotinylated heparin was successfully grafted onto photobiotin/avidin arrays.

JTD Keywords: Antifouling, Heparin, Malaria, Microcontact arrayer, Microcontact printing, Micropatterning, Perfluoropolyether, Photobiotin, Polymers, Soft lithography

JTD Keywords: antimalarial, heparin, magic bullet, malaria, nanomedicine, nanotechnology, nanovector, Plasmodium, polymers, targeted drug delivery, chloroquine, immunoliposome, liposome, nanoparticle, solid lipid nanoparticle, Anopheles, antimalarial activity, drug delivery system, drug efficacy, erythrocyte, human, IC50, malaria, malaria control, nanoencapsulation, nonhuman, pathophysiology, Plasmodium, Review

Heparin had been demonstrated to have antimalarial activity and specific binding affinity for Plasmodium-infected red blood cells (pRBCs) vs. non-infected erythrocytes. Here we have explored if both properties could be joined into a drug delivery strategy where heparin would have a dual role as antimalarial and as a targeting element of drug-loaded nanoparticles. Confocal fluorescence and transmission electron microscopy data show that after 30. min of being added to living pRBCs fluorescein-labeled heparin colocalizes with the intracellular parasites. Heparin electrostatically adsorbed onto positively charged liposomes containing the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane and loaded with the antimalarial drug primaquine was capable of increasing three-fold the activity of encapsulated drug in Plasmodium falciparum cultures. At concentrations below those inducing anticoagulation of mouse blood in vivo, parasiticidal activity was found to be the additive result of the separate activities of free heparin as antimalarial and of liposome-bound heparin as targeting element for encapsulated primaquine. From the Clinical Editor: Malaria remains an enormous global public health concern. In this study, a novel functionalized heparin formulation used as drug delivery agent for primaquine was demonstrated to result in threefold increased drug activity in cell cultures, and in a murine model it was able to provide these benefits in concentrations below what would be required for anticoagulation. Further studies are needed determine if this approach is applicable in the human disease as well.

JTD Keywords: Heparin, Liposomes, Malaria, Plasmodium, Targeted drug delivery, Heparin, Malaria, Plasmodium, Red blood cell, Targeted drug delivery, Liposomes, 1,2 dioleoyl 3 trimethylammoniopropane, fluorescein, heparin, liposome, nanoparticle, primaquine, adsorption, animal experiment, anticoagulation, antimalarial activity, Article, binding affinity, confocal microscopy, controlled study, drug targeting, encapsulation, erythrocyte, female, fluorescence microscopy, human, human cell, in vivo study, liposomal delivery, mouse, nonhuman, Plasmodium falciparum, transmission electron microscopy

JTD Keywords: Antimalarial, Erythrocyte, Glycosaminoglycan, Heparin, Magic bullet, Malaria, Nanomedicine, Nanovector, Plasmodium, Targeted drug delivery

JTD Keywords: Antimalarial, Erythrocyte, Glycosaminoglycan, Heparin, Magic bullet, Malaria, Nanomedicine, Nanovector, Plasmodium, Targeted drug delivery

Adhesion of tissue cells is a prerequisite for their growth and differentiation but prevents also apoptosis. Here the layer-by-layer technique (LbL) was used to design multilayer structures of poly(ethylene imine) (PEI) and heparin (HEP) on glass as model biomaterial to control the adhesion of primary human dermal fibroblasts. Distinct surface features like wettability, charge and lateral structures were controlled by changing the pH value of the HEP solution during multilayer assembly to acidic neutral or alkaline, values. While plain terminal layers were rather cytophobic, the pre-adsorption of serum or fibronectin (FN) caused a distinct change in cell morphology in dependence on the pH setup. The effect of serum was more prominent on PEI layers probably due to their positive surface charge, whereas the effect of FN was more pronounced on HEP terminated multilayers possibly due to its ability to bind FN specifically. Those layers which hampered cell adhesion also inhibited growth of human fibroblasts under serum conditions. Conversely, on layers where cell adhesion was increased also an elevated growth and, thus, metabolic activity was observed.

JTD Keywords: Surface modification, Layer-by-layer, Poly(ethylene imine), Heparin, Serum, Fibronectin