Light-switchable lignin-based nanospheres for photodynamic eradication of drug-resistant pathogens and ROS scavenging

Area of Science:

• Biomaterials Science
• Nanotechnology
• Antimicrobial Research

Background:

• Rising drug-resistant bacteria necessitate sustainable antimicrobial solutions.
• Natural lignin offers potential as a building block for eco-friendly biomaterials.
• Synthetic antimicrobials pose an ecological burden.

Purpose of the Study:

• To develop a novel lignin-derived nanocarrier system for enhanced antibacterial photodynamic inactivation.
• To create a biocompatible and highly efficient antimicrobial agent using lignin, a sustainable byproduct.
• To investigate the combined antibacterial and antioxidant properties of the developed nanospheres.

Main Methods:

• Kraft lignin was modified into aminated and then acetylated lignin.
• Modified lignin encapsulated chlorin e6 (photosensitizer) and was coated with chitosan, forming CS-ML-Ce6 nanospheres.
• Photodynamic inactivation, minimum inhibitory concentration, hemolysis assays, and reactive oxygen species scavenging were evaluated.

Main Results:

• CS-ML-Ce6 achieved >99.99% bactericidal efficiency against methicillin-resistant Staphylococcus aureus upon laser irradiation.
• The minimum inhibitory concentration of modified lignin under light was 67.71 μg/mL.
• CS-ML-Ce6 showed enhanced bacterial adsorption, significant dead/live rates compared to controls, and excellent biocompatibility (hemolysis <5%).

Conclusions:

• Lignin-derived nanospheres (CS-ML-Ce6) present a potent, light-activated antimicrobial strategy against drug-resistant pathogens.
• The dual-function approach combines photodynamic inactivation with antioxidant properties for comprehensive therapeutic effects.
• This sustainable, lignin-based system offers a promising alternative to conventional antibiotics for healthcare applications.