Publications

The fabrication of porous biophotonic scaffold using a robocasting is reported here. Such material could be used for in-situ activation of photoswitchable drugs, which is essential for improving therapeutic efficacy while minimizing side effects. The scaffold is made of a phosphate glass mixed with CaWO4:Yb3 +,Tm3 + crystals and SrAl2O4:Eu2+,Dy3 + phosphors. Upon 980 nm irradiation, the scaffold emits blue light and green afterglow, enabling in-situ activation post-implantation as NIR light penetrates tissue. The challenges related to the sintering process and its effect on the spectroscopic properties of the scaffold are discussed. The as-3D printed scaffold successfully enables one to activate the muscarinic photoswitchable drug Phthal Azobenzene Iperoxo (PAI) upon NIR excitation, confirming the potential for in-situ phototriggered delivery of drug action using tissue-permeable light stimulus.

JTD Keywords: Artificial skin, Bioactive glass, Cawo4 upconverter crystals, Design, Er3+, Nanocrystals, Persistent luminescence, Photoswitchable molecule, Scaffold, Surface, Up-conversion

Despite significant efforts in developing novel biomaterials to regenerate tissue, only a few of them have successfully reached clinical use. It has become clear that the next generation of biomaterials must be multifunctional. Smart biomaterials can respond to environmental or external stimuli, interact in a spatial-temporal manner, and trigger specific tissue/organism responses. In this study, the fabrication of novel 3D-printed and bioresorbable scaffolds, with embedded crystals that can convert near-infrared (NIR) light into visible light, is presented. It is demonstrated that these biophotonic scaffolds are not only bioactive and bioresorbable, but can also be promising as a platform for the controlled release or activation of photoactivated drugs locally and on demand, under illumination. The scaffolds are analyzed based on their up-conversion spectroscopic properties and their chemical stability in simulated body fluid. Furthermore, it is demonstrated that the up-conversion properties of the scaffolds are sufficient to release the signaling molecule nitric oxide (NO) and to photoisomerize the muscarinic ligand Phthalimide-Azo-Iperoxo (PAI), in a controlled manner, upon NIR light stimulus. Finally, to assess their biocompatibility for potential implantation, a preliminary study is conducted with human adipose stem cells cultured in contact with scaffolds. Live/dead assays, morphological analysis, CyQUANT analysis, and ion release measurements confirm that, despite some release of the upconverter crystals, the biophotonic materia and its dissolution by-products, are biocompatible. These findings highlight the potential of these bioresorbable biophotonic scaffolds for localized drug release in response to NIR light stimuli.

JTD Keywords: 45s, 45s5, Bioactive glass scaffolds, Borate, Bulk, Drug targeting, Implants, Luminescence, Nitric oxide, Optopharmacology, Photopharmacology, Phototherapeutic window, Silicate, System, Upconversio, Upconversion

Objective: Wound healing is a complex process that involves the interaction between different cell types and bioactive factors. Impaired wound healing is characterized by a loss in synchronization of these interactions, resulting in nonhealing chronic wounds. Chronic wounds are a socioeconomic burden, one of the most prominent clinical manifestations of diabetes, however, they lack satisfactory treatment options. The objective of this study was to develop polymeric composites that deliver ions having wound healing properties and evaluate its performance using a pressure ulcer model in diabetic mice. Approach: To develop a polymeric composite wound dressing containing ion-releasing nanoparticles for chronic wound healing. This composite was chemically and physically characterized and evaluated using a pressure ulcer wound model in diabetic (db/db) mice to explore their potential as novel wound dressing. Results: This dressing exhibits a controlled ion release and a goodin vitrobioactivity. The polymeric composite dressing treatment stimulates angiogenesis, collagen synthesis, granulation tissue formation, and accelerates wound closure of ischemic wounds created in diabetic mice. In addition, the performance of the newly designed composite is remarkably better than a commercially available dressing frequently used for the treatment of low-exuding chronic wounds. Innovation: The developed nanoplatforms are cell- and growth factor free and control the host microenvironment resulting in enhanced wound healing. These nanoplatforms are available by cost-effective synthesis with a defined composition, offering an additional advantage in potential clinical application. Conclusion: Based on the obtained results, these polymeric composites offer an optimum approach for chronic wound healing without adding cells or external biological factors.

JTD Keywords: angiogenesis, bioactive dressings, chronic wounds, Angiogenesis, Bioactive dressings, Bioactive glass, Bioglass, Cells, Chronic wounds, Diabetes, Endothelial growth-factor, Expression, Hydrogel, Induction

Abstract The aim of the present study was the in vitro and in vivo analysis of a bi-layered 3D-printed scaffold combining a PLA layer and a biphasic PLA/bioglass G5 layer for regeneration of osteochondral defects in vivo Focus of the in vitro analysis was on the (molecular) weight loss and the morphological and mechanical variations after immersion in SBF. The in vivo study focused on analysis of the tissue reactions and differences in the implant bed vascularization using an established subcutaneous implantation model in CD-1 mice and established histological and histomorphometrical methods. Both scaffold parts kept their structural integrity, while changes in morphology were observed, especially for the PLA/G5 scaffold. Mechanical properties decreased with progressive degradation, while the PLA/G5 scaffolds presented higher compressive modulus than PLA scaffolds. The tissue reaction to PLA included low numbers of BMGCs and minimal vascularization of its implant beds, while the addition of G5 lead to higher numbers of BMGCs and a higher implant bed vascularization. Analysis revealed that the use of a bi-layered scaffold shows the ability to observe distinct in vivo response despite the physical proximity of PLA and PLA/G5 layers. Altogether, the results showed that the addition of G5 enables to reduce scaffold weight loss and to increase mechanical strength. Furthermore, the addition of G5 lead to a higher vascularization of the implant bed required as basis for bone tissue regeneration mediated by higher numbers of BMGCs, while within the PLA parts a significantly lower vascularization was found optimally for chondral regeneration. Thus, this data show that the analyzed bi-layered scaffold may serve as an ideal basis for the regeneration of osteochondral tissue defects. Additionally, the results show that it might be able to reduce the number of experimental animals required as it may be possible to analyze the tissue response to more than one implant in one experimental animal.

JTD Keywords: Bioactive glass, Polylactic acid (PLA), Bi-layer scaffold, Multinucleated giant cells, Bone substitute, Vascularization, Calcium phosphate glass

Bioactive nanocomposite scaffolds with cell-adhesive surface have excellent bone regeneration capacities. Fibronectin (FN)-immobilized nanobioactive glass (nBG)/polycaprolactone (PCL) (FN-nBG/PCL) scaffolds with an open pore architecture were generated by a robotic-dispensing technique. The surface immobilization level of FN was significantly higher on the nBG/PCL scaffolds than on the PCL scaffolds, mainly due to the incorporated nBG that provided hydrophilic chemical-linking sites. FN-nBG/PCL scaffolds significantly improved cell responses, including initial anchorage and subsequent cell proliferation. Although further in-depth studies on cell differentiation and the in vivo animal responses are required, bioactive nanocomposite scaffolds with cell-favoring surface are considered to provide promising three-dimensional substrate for bone regeneration.

JTD Keywords: Bone scaffolds, Cell response, Fibronectin, Nanobioactive glass, Nanocomposites, Polycaprolactone, Bone, Cell proliferation, Cells, Cytology, Glass, Nanocomposites, Polycaprolactone, Robotics, Bone scaffolds, Bone tissue engineering, Cell response, Fibronectin, Fibronectin immobilizations, Nano bioactive glass, Nanocomposite scaffolds, Three-dimensional substrates, Scaffolds (biology)

In this study, polylactic acid (PLA) and polyethylene glycol (PEG) were combined with soluble CaP glass particles and processed by rapid prototyping to obtain fully biodegradable structures for Tissue Engineering applications. The obtained 3D biodegradable structures were characterized in terms of their architecture and mechanical properties. The scaffold morphology, internal micro-architecture and mechanical properties were evaluated using Scanning Electron Microscopy (SEM), micro-computed tomography (micro-CT) and mechanical testing, respectively. Well defined structures with pore size of 350-400μm (in the axial view), struts width of approximately 70-80μm, and a porosity ranging between 60-65% were obtained. The combination RP and PLA/PEG/CaP glass turned into promising fully degradable, mechanically stable, bioactive and biocompatible composite scaffolds for TE.

JTD Keywords: Axial view, Biodegradable composites, Composite scaffolds, Glass particles, Mechanically stable, Micro architectures, Micro computed tomography (micro-CT), Poly lactic acid, Scaffold morphology, Tissue engineering applications, Well-defined structures, Bioactive glass, Mechanical properties, Mechanical testing, Polyethylene glycols, Polymer blends, Rapid prototyping, Scaffolds (biology), Scanning electron microscopy, Computerized tomography