Antimicrobial Applications of Photosensitizer-Embedded Cationic Hydrogels with Tunable Mechanical Properties against Multidrug-Resistant Pathogens

Drug resistance among infectious pathogens is rapidly escalating, posing a significant global public health challenge that complicates the treatment of hospital-acquired zoonotic infections. In this study, we developed a Rose Bengal (RB)-embedded poly(AEMA-TEGDMA) hydrogel as an innovative photodynamic antimicrobial wound dressing for combating multidrug-resistant (MDR) infections. Fabricated via UV-induced photopolymerization within 30 minutes, the hydrogel is composed of 2-aminoethyl methacrylate hydrochloride (AEMA) and tetraethylene glycol dimethacrylate (TEGDMA). The cationic, low-toxicity AEMA facilitates RB incorporation through electrostatic interactions and chain entanglement, ensuring uniform distribution, as confirmed by fluorescence microscopy and SEM-EDS. Upon visible light excitation, the hydrogel generates reactive oxygen species via a type II photodynamic mechanism, inducing oxidative damage to pathogens. Under portable LED illumination (400–700 nm, λmax = 445 nm; 48 ± 2 mW/cm2 for 15 or 30 min), the hydrogel demonstrated potent antimicrobial efficacy against both Gram-positive [methicillin-resistant Staphylococcus aureus (MRSA; ATCC-44) and multidrug-resistant Staphylococcus pseudintermedius (MRSP)] and Gram-negative [multidrug-resistant Acinetobacter baumannii (MDRAB; ATCC-1605) and NDM-1-positive Klebsiella pneumoniae (KP; ATCC-2146)] bacteria, achieving up to 99.9999% (6-log) inactivation against MRSP within 15 min. Antiviral studies against HCoV-229E, adenovirus, and rhinovirus also resulted in detection limit inactivation within 15 min. Furthermore, tuning the monomer-to-cross-linker ratio allowed modulation of the hydration and mechanical properties of the hydrogels, with the compressive toughness ranging from 5.0 ± 0.6 to 186.9 ± 115.1 kJ/m3, thereby enhancing their versatility for biomedical applications. These results underscore the potential of photodynamic antimicrobial wound dressings as a proactive strategy to mitigate MDR infections in both humans and companion animals.