Xylan–Porphyrin Hydrogels as Light-Triggered Gram-Positive Antibacterial Agents

Abstract

In the present work, we report on the synthesis of light-triggered antibacterial hydrogels, based on xylan chains covalently bound to meso-tetra(4-carboxyphenyl)porphyrin (TCPP). Not only does TCPP act as a photosensitizer efficient against Gram-positive bacteria, but it also serves as a cross-linking gelator, enabling the simple and easy building of xylan conjugate hydrogels. The hydrogels were characterized by infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), along with swelling and rheological tests. The antimicrobial activity of the hydrogels was tested under visible light irradiation against two Gram-positive bacterial strains, Staphylococcus aureus and Bacillus cereus. The preliminary results showed an interesting activity on these bacteria, indicating that these hydrogels could be of great potential in the treatment of skin bacterial infections with this species by photodynamic antimicrobial chemotherapy (PACT).

In Situ Single-Cell Bacterial Imaging Provides Mechanistic Insight into the Photodynamic Action of Photosensitizer-Loaded Hydrogels

“…These materials are becoming important as a promising solution for wound management due to their tunability, softness, permeability, biocompatibility, or biodegradability. − In the context of drug delivery, hydrogels benefit from their porosity, which enables drug encapsulation within a 3D polymeric network. Some antibacterial hydrogels have been particularly valuable in the context of light-induced therapies such as antimicrobial photodynamic therapy (aPDT). − aPDT combines light, molecular oxygen, and a photosensitizer to generate reactive oxygen species (ROS) that oxidize lipids, proteins, DNA, and other biomolecules, leading to bacterial inactivation. − Good transparency is, therefore, needed for hydrogels to perform well in aPDT, especially for wound dressing applications, and previous work has focused on optimizing their optical properties. , It was shown that electron-beam polymerized polyethylene glycol diacrylate (PEGDA) hydrogels have a higher transmittance over a broader wavelength range compared to their UV-cured counterparts, reaching values well above 90% …”