Near-infrared photodynamic antibacterial enhanced superhydrophobic electrospun membrane surfaces

Superhydrophobic surfaces have attracted great attention as effective antimicrobial platforms due to the superb repellency against various microbial biofouling. However, due to the lack of intrinsic antimicrobial activity, some bacteria still have the opportunity to adhere and survive on superhydrophobic surfaces, inevitably causing serious bacterial contamination. Herein, a poly(vinylidene) fluoride (PVDF) based nanocomposite membrane with both superhydrophobic property and near-infrared (NIR) light triggered photodynamic antibacterial activity has been prepared by a facile electrospinning method. Among those, the silicon dioxide nano-scale particles were introduced in the membrane to increase the roughness of the electrospun fibres, while the zinc phthalocyanine (ZnPC) as the NIR photosensitizer was also involved. Owing to the stable Cassie-Baxter model superhydrophobic properties, the resultant membrane demonstrated strong bacterial repellent performances for both Gram-positive and Gram-negative bacteria (~8.9 % reduction for S. aureus and ~9.4 % for E. coli). After being exposed to NIR light illumination (808 nm, 2.0 mW) for 10 min, the membrane surface showed further enhanced antimicrobial efficiency and no surviving bacteria were observed, which is extremely difficult to achieve by relying on either superhydrophobic repellency or NIR photodynamic sterilization alone. Furthermore, this nanocomposite membrane displays no detectable cytotoxicity to L929 cells, even suffered from NIR light irradiation, and the surface also shows no significant activation on red blood cells as well as good liquid-repellency against whole blood adhesion. These results conclusively show that the nanocomposite membranes exhibit great potential applications in a wide range of antimicrobial-related fields.