Development of an Antimicrobial-Coated Absorbable Monofilament Suture from a Medical-Grade Poly(l-lactide-co-ε-caprolactone) Copolymer.

In this study, a medical-grade poly(l-lactide-co-ε-caprolactone) (PLC) copolymer with a monomer ratio of l-lactide (L) to ε-caprolactone (C) of 70:30 mol % for use as an absorbable surgical suture was synthesized via ring-opening polymerization (ROP) using a novel soluble liquid tin(II) n-butoxide (Sn(OnC4H9)2) as an initiator. In fiber fabrication, the process included copolymer melt extrusion with a minimal draw followed by sequential controlled hot-drawing and fixed-annealing steps to obtain oriented semicrystalline fibers with improved mechanical strength. For healing enhancement, the fiber was dip-coated with "levofloxacin" by adding the drug into a solution mixture of acetone, poly(ε-caprolactone) (PCL), and calcium stearate (CaSt) in the ratio of acetone/PCL/CaSt = 100:1% w/v:0.1% w/v. The tensile strength of the coated fiber was found to be increased to ∼400 MPa, which is comparable with that of commercial polydioxanone (PDS II) of a similar size. Finally, the efficiency of the drug-coated fiber regarding its controlled drug release and antimicrobial activity was investigated, and the results showed that the coated fiber was able to release the drug continuously for as long as 30 days. For fiber antimicrobial activity, it was found that a concentration of 1 mg/mL was sufficient to inhibit the growth of Staphylococcus aureus (MRSA), Escherichia coli O157:H7, and Pseudomonas aeruginosa, giving a clear inhibition zone range of 20-24 mm for 90 days. Cytotoxicity testing of the drug-coated fibers showed a %viability of more than 70%, indicating that they were nontoxic.

Optimization and characterization of red pigment production from an endophytic fungus, Nigrospora aurantiaca CMU-ZY2045, and its potential source of natural dye for use in textile dyeing.

Some of the most important natural pigments have been produced from fungi and used for coloring in food, cosmetics, textiles, and pharmaceutical products. Forty-seven isolates of endophytic fungi were isolated from Cinnamomum zeylanicum in northern Thailand. Only one isolate, CMU-ZY2045, produced an extracellularly red pigment. This isolate was identified as Nigrospora aurantiaca based on morphological characteristics and the molecular phylogenetic analysis of a combined four loci (large subunit and internal transcribed spacer of ribosomal DNA, ß-tubulin, and translation elongation factor 1-alpha genes). The optimum conditions for red pigment production from this fungus were investigated. The results indicated that the highest red pigment yield was observed in the liquid medium containing glucose as a carbon source and yeast extract as a nitrogen source, at a pH value of 5.0 and at 27 °C with shaking for 5 days. The crude red pigment revealed the highest level of solubility in methanol. A fungal red pigment was found to have high stability at temperatures ranging from 20 to 50 °C and pH values at a range of 5.0-6.0. Based on liquid chromatography-mass spectrometry analyses, the red pigment was characterized as bostrycin. The extracted pigment was used for the textile dyeing process. Crude fungal red pigment revealed the highest staining ability in cotton fabrics and displayed excellent fastness to washing, which showing negative cytotoxicity at the concentrations used to cell culture. This is the first report on bostrycin production from N. aurantiaca.