3D bioprinted scaffolds for diabetic wound-healing applications

The treatment strategy required for the effective healing of diabetic foot ulcer (DFU) is a complex process that is requiring several combined therapeutic approaches. As a result, there is a significant clinical and economic burden associated in treating DFU. Furthermore, these treatments are often unsuccessful, commonly resulting in lower-limb amputation. The use of drug-loaded scaffolds to treat DFU has previously been investigated using electrospinning and fused deposition modelling (FDM) 3D printing techniques; however, the rapidly evolving field of bioprinting is creating new opportunities for innovation within this research area. In this study, 3D-bioprinted scaffolds with different designs have been fabricated for the delivery of an antibiotic (levoflocixin) to DFU. The scaffolds were fully characterised by a variety of techniques (e.g. SEM, DSC/TGA, FTIR, and mechanical characterisation), demonstrating excellent mechanical properties and providing sustained drug release for 4 weeks. This proof of concept study demonstrates the innovative potential of bioprinting technologies in fabrication of antibiotic scaffolds for the treatment of DFU.

In situ synthesis and characterization of silver/polymer nanocomposites by thermal cationic polymerization processes at room temperature: initiating systems based on organosilanes and starch nanocrystals

New methods for the preparation of silver nanoparticles/polymer nanocomposite materials by thermal cationic polymerization of ε-caprolactone (ε-CL) or α-pinene oxide (α-PO) at room temperature (RT) and under air were developed. The new initiating systems were based on silanes (Si), starch nanocrystals (StN) and metal salts. Excellent polymerization profiles were revealed. It was shown that silver nanoparticles (Ag(0) NPs) were in situ formed and that the addition of StN improves the polymerization efficiency. The as-synthesized nanocomposite materials contained spherical nanoparticles homogeneously dispersed in the polymer matrices. Polymers and nanoparticles were characterized by gel permeation chromatography (GPC), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. A coherent picture of the involved chemical mechanisms is presented.

Poly(lactic acid) Composites Directly Molded from Lactide and Particle Fillers

Polymer composite samples consisting of L-Lactic acid (LA) was reacted by ring-opening polymerization with aluminum triflate as a catalyst, glycerol as an initiator and various particles as fillers. Cellulose particles, kaolin and silica gel with different particle sizes were employed as fillers. Filler content was varied 0 to 100 wt% as ratio of filler weight to PLA weight. L-Lactide (L-LA), aluminum triflate as catalyst, glycerol as an initiator and particles were mixed at room temperature and then were put into plastic tubes. The mixture in tubes was heated and reacted at 100 oC for 6 hours. The samples were removed from tubes after cooling and were cut into the column shape specimen with diameter of 10 mm and ca. 10 mm height. By the above procedure, particles could be mixed to poly(lactic acid) (PLA) matrix easily and homogeneously. The molecular weight and molecular weight distribution of PLA matrix were determined by gel permeation chromatography (GPC). Apparent density of composite samples was calculated by using weight and sizes of column shape specimens. The mechanical properties such as elastic modulus and strength were investigated by compression tests using column shape specimens. Molecular weight and molecular weight distribution were almost constant for all the samples with and without particles. Elastic modulus and compression strength were improved by particles. For the cellulose particles filled samples, the highest values of elastic modulus and compression strength were derived at filler content of around 20 vol%. The influences of sizes and types of particles on the physical properties such as molecular weight, density and mechanical properties were investigated.