Antimicrobial activity and mechanism of PLA/TP composite nanofibrous films

Abstract

Electrospinning is conducted with polylactic acid (PLA) and tea polypheno (TP) to obtain PLA/TP composite nanofibrous films with high antimicrobial activity. An investigation of the composition, antimicrobial activity, and mechanism of these composite nanofibrous films was conducted by using infrared spectroscopy (FT-IR), inhibition zone method, fluorescence activated cell sorter (FACS), and transmission electron microscope (TEM). IR spectra results showed that TP and PLA composited well through valence bonds in PLA/TP composite nanofibrous films. Ranges of the inhibition zone for the growth of Escherichia coli (E. coli) and Staphylococcus (Staphylococcus aureus) were 3.67 and 3.71 cm in pure PLA nanofibrous films, but 5.17 and 5.67 cm in PLA/TP composite nanofibrous films, respectively. Results indicated that the antimicrobial activity of PLA/TP composite nanofibrous films were much higher than that of pure PLA nanofibrous films. Meanwhile, the antimicrobial activity against S. aureus was also slightly higher than E. coli. FACS results showed that the positive rate of PLA/TP composite nanofiber films was greater than that of pure PLA nanofibrous films, increasing from 1.45 and 0.78% to 9.26 and 6.47% against S. aureus and E. coli, respectively. The result of TEM indicated that PLA/TP composite nanofibrous films led to the death of bacteria by destroying the integrity of cell membrane.

Keywords:

• tea polypheno
• polylactic acid
• electrospinning
• nanofibrous film
• antibacterial mechanism

Acknowledgements

The authors wish to acknowledge the financial support from (1) Jiangnan university scientific research fund for doctoral students; (2) The Jiangsu Provincial Natural Science Foundation of China (No. BK2012112); (3) The National Natural Science Foundation of China under Grant Nos. 31201134 and 51203066; (4) Industry-academic Joint Technological Prospective Fund Project of Jiangsu Province (No. BY2013015-24).