Preparation of photodynamic P(MMA-co-MAA) composite nanofibers doped with MMT: A facile method for increasing antimicrobial efficiency

Abstract

We report the preparation of photodynamic materials from electrospun nanofibers of P(MMA-co-MAA) co-polymer that were doped with montmorillonite (MMT), and further functionalized with the cationic photosensitizer methylene blue (MB). The resultant composite nanofibers were characterized by spectroscopic (infrared, UV − vis, fluorescence) and physical (SEM/TEM, gravimetric) methods. Addition of MMT (0–6 wt%) in the electrospinning process increased the adsorption of the methylene blue photosensitizer from 21.5 mg (67.1 μmol)/g P(MMA-co-MAA) parent copolymer to 30.0 mg (93.8 μmol)/g P(MMA-co-MAA)/MMT-6 composite nanofibers. The MB-decorated P(MMA-co-MAA)/MMT-6 composite nanofibers showed a 99.997% (4.8 log units) and 97% (1.8 log units) reduction in CFU/mL against Staphylococcus aureus (ATCC-6538) and Escherichia coli strain 8099, respectively, after visible light illumination (LED lamp, 30 min, 35 ± 5 mW/cm2), demonstrating that the increased photosensitizer loading attributable to MMT doping led to a 1–2 log unit increase in photodynamic inactivation efficacy over the non-doped MB-decorated P(MMA-co-MAA) parent copolymer (99.9% and 84% reduction for S. aureus and E. coli, respectively). The results demonstrate that MMT and similar additives may be a universal method for increasing the adsorption capacity of cationic photosensitizers in electrospun nanofibers, thereby generating materials with improved photodynamic inactivation efficacy without significantly changing the fiber morphology, cost, or ease of production.