Effect of stereoisomerism of poly(lactic acid) during neural guide conduit membrane synthesis

Abstract

Poly(lactic acid) membranes are being developed as biomaterials for several purposes such as artificial implants for peripheral nerve injury, also known as neural guide conduits (NGC). These membranes need to meet standards of mechanical, degradability, and permeability properties, besides dimensional and structural requirements. Among the stereoisomers of polylactides, poly(l‐lactic acid), and poly(d,l‐lactic acid) are the most used as biomaterials, having significant differences in solubility, crystallinity thermal, and mechanical properties. In this work, PLLA and PDLLA were compared for hollow fiber membrane synthesis by liquid induced phase separation. PLLA samples presented 18% of crystallinity, while PDLLA is amorphous. PDLLA and PLLA polymer solutions on N‐methyl‐pyrrolidone presented values of 3428 and 320.2 cP, respectively. In immersion of PLA‐NMP solutions in water, PLLA solution presented instantaneous demixing, while PDLLA showed a 28 s delay on precipitation. The PLLA–NMP–water has a larger demixing region compared to PDLLA–NMP–water system. Hollow fibers of both polymers presented closed external surface with finger‐like macropores morphology in their cross‐sections. PDLLA presented typical liquid–liquid demixing pores while PLLA presented spherulitical crystalline solid–liquid separation structures, which deeply compromised its mechanical properties. PDLLA presented as a good candidate for hollow fiber NGC material, as presented good mechanical resistance in tensile and suture simulating tests. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46190.

Coaxial electrospinning preparation and antibacterial property of polylactic acid/tea polyphenol nanofiber membrane

“…According to the working principle of constant speed elongation, a certain length of fiber membrane was stretched at a constant speed to break, and the tensile strength and elongation at break of the fiber membrane were recorded. 25 All membranes were cut into 2 mm × 40 mm. The thickness of each membrane was measured by the digital micrometer (0–12.77 mm, Henan Bangte Tools) for 10 times.…”

“…Moreover, under the condition that the volume of the solution remained unchanged, while a certain volume of solution was taken out, the same volume of pure phosphate buffered solution could be added. 25 The whole sampling time lasted for 48 h. According to the absorbance tests and the standard fitting line in Supplementary Figure S1, the concentration of antimicrobial agent in phosphate buffered solution at a specific time could be obtained. Finally, different PLA/TP mass ratios in the shell of the nanofiber membranes at different times were obtained through the cumulative release formula.…”