Photo-crosslinkable recombinant collagen mimics for tissue engineering applications

Gelatin is frequently used in various biomedical applications. However, gelatin is generally extracted from an animal source, which can result in issues with reproducibility as well as pathogen transmittance. Therefore, we have investigated the potential of a recombinant peptide based on collagen I (RCPhC1) for tissue engineering applications and more specifically for adipose tissue regeneration. In the current paper, RCPhC1 was functionalized with photo-crosslinkable methacrylamide moieties to enable subsequent UV-induced crosslinking in the presence of a photo-initiator. The resulting biomaterial (RCPhC1-MA) was characterized by evaluating the crosslinking behaviour, the mechanical properties, the gel fraction, the swelling properties and the biocompatibility. The obtained results were compared with the data obtained for methacrylamide-modified gelatin (Gel-MA). The results indicated that the properties of RCPhC1-MA networks are comparable to those of animal-derived Gel-MA. RCPhC1-MA is thus an attractive synthetic alternative for animal-derived Gel-MA and is envisioned to be applicable for a wide range of tissue engineering purposes

Polyester-based biodegradable optical fiber building blocks : versatile tools for biomedical applications

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Synergistic effect of κ-carrageenan and gelatin blends towards adipose tissue engineering

The current paper focuses on the functionalization of kappa-carrageenan and gelatin as extracellular matrix polysaccharide and protein mimic respectively to produce hydrogel films for adipose tissue engineering. More specifically, kappa-carrageenan as well as gelatin have been functionalized with methacrylate and methacrylamide moieties respectively to enable subsequent UV-induced crosslinking in the presence of a photo-initiator. The gel fraction, the mass swelling ratio and the mechanical properties of both the one-component hydrogels and the protein/polysaccharide blends have been evaluated. The mechanical and swelling properties of the blends could be tuned by varying the hydrogel composition as well as the crosslinking method applied. The in vitro bio-compatibility assays indicated a significantly higher cell viability of adipose tissue-derived mesenchymal stem cells seeded onto the blends as compared to the one-component hydrogels. The results show that the blends of gelatin and kappa-carrageenan clearly outperform the one-component hydrogels in terms of adipose tissue engineering potential

On the characterization of novel step-index biocompatible and biodegradable poly(D,L-lactic acid) based optical fiber

We report on the first step-index biodegradable polymer optical fiber (bioPOF) fabricated using commercially available polyesters, with a core made from poly(D,L-lactic-co-glycolic acid) and a cladding made from poly(D,L-lactic acid). We prepared the preforms with a rod-in-tube technique and the fibers with a standard heat drawing process. We discuss the chemical and optical properties of the polyesters along the fabrication process from polymer granulates to optical fiber. More specifically, we address the influence of the processing steps on the molecular weight and thermal properties of the polymers. Cutback measurements return an attenuation of 0.26 dB/cm at 950 nm for fibers with an outer diameter of 1000 +/- 50 mu m, a core of 570 +/- 30 mu m, and a numerical aperture of 0.163. When immersed in phosphate-buffered saline (PBS), bioPOFs degrade over a period of 3 months, concurrent with a 91% molecular weight loss. The core decomposes already after three weeks and features 85% molecular weight loss. There is no any additional optical loss caused by immersion in PBS during the first 30-40 min for a bioPOFs with a diameter of about 500 mu m. Our result demonstrates that bioPOF can be suitable for applications requiring light delivery, deep into living tissue, such as photodynamic therapy

Amorphous random copolymers of lacOCA and manOCA for the design of biodegradable polyesters with tuneable properties

Biodegradable polymers derived from renewable resources can be interesting materials for a plethora of applications and have therefore gained increased interest over the last decades. We herein report for the first time the synthesis of random copolymers based on lactic and mandelic acid via ring-opening-polymerisation of their corresponding 0-carboxyanhydrides (OCA). Copolymers with tailored glass transition temperature and degradation time were obtained by adjusting the co-monomer feed during copolymerisation. Molecular weight analyses of the obtained copolymers indicated lower molecular weights in comparison to the target values. Our hypothesis that keto-enol tautomerisation of the OCA-monomers was the cause for this anomaly was substantiated by a mechanistic study of the OCA-polymerization reaction using lacOCA and manOCA as case study

Poly(D, L-lactic acid) (PDLLA) biodegradable and biocompatible polymer optical fiber

We demonstrate that commercially available poly(D, L-lactic acid) (PDLLA) is a suitable material for the fabrication of biodegradable optical fibers with a standard heat drawing process. To do so we report on the chemical and optical characterization of the material. We address the influence of the polymer processing on the molecular weight and thermal properties of the polymer following the preparation of the polymer preforms and the fiber optic drawing process. We show that cutback measurements of the first optical fibers drawn fromPDLLA return an attenuation coefficient as low as 0.11 dB/cm at 772 nm, which is the lowest loss reported this far for optical fibers drawn from bio-resorbable material. We also report on the dispersion characteristics of PDLLA, and we find that the thermo-optic coefficient is in the range of -10-4 degrees C-1. Finally, we studied the degradation of PDLLA fibers in vitro, revealing that fibers with the largest diameter of 600 mu m degrade faster than those with smaller diameters of 300 and 200 mu m and feature more than 84% molecular weight loss over a period of 3 months. The evolution of the optical loss of the fibers as a function of time during immersion in phosphate-buffered saline indicates that these devices are potential candidates for use in photodynamic therapy-like application scenarios