Antibacterial properties of photocrosslinkable hydrogel loaded with quercetin-silver nanoparticles for infected wounds

Abstract

BACKGROUND: Numerous studies have confirmed that quercetin can inhibit the release of inflammatory factors and reduce local inflammatory responses in wounds, creating favorable conditions for wound healing. However, quercetin has poor water solubility and low bioavailability, which limits its application in wound treatment. OBJECTIVE: To investigate the antibacterial properties of quercetin-silver nanoparticle/methacrylated hyaluronic acid composite hydrogels. METHODS: Quercetin-silver nanoparticles (QuAgNPs) were synthesized by hydrothermal reduction method. QuAgNPs were loaded into methacrylated hyaluronic acid (HAMA) hydrogel precursor solution at different mass concentrations (1, 5, 10, 20, 40, 60, 80 μg/mL) to prepare composite hydrogels, denoted as 1, 5, 10, 20, 40, 60, 80 μg/mL QuAgNPs/HAMA hydrogels, while pure HAMA hydrogels were also prepared. Staphylococcus aureus was co-cultured with 1, 5, 10, 20, 40, 60, 80 μg/mL QuAgNPs/HAMA hydrogels, and antibacterial properties were detected by inhibition zone experiment. In vitro drug release properties of 60 and 80 μg/mL QuAgNPs/HAMA hydrogels were tested. Based on the results of the inhibition zone experiment, appropriate QuAgNPs/HAMA hydrogels were selected for subsequent experiments. The microstructure of HAMA hydrogel and 60 μg/mL QuAgNPs/HAMA hydrogel was observed under scanning electron microscope. Staphylococcus aureus (or Escherichia coli) were co-cultured with QuAgNPs, HAMA hydrogel, and 60 μg/mL QuAgNPs/HAMA hydrogel, with bacteria cultured alone as blank control, and antibacterial rates were detected by spread plate antibacterial experiment. Human umbilical vein endothelial cells were co-cultured with QuAgNPs, HAMA hydrogel extract, and 60 μg/mL QuAgNPs/HAMA hydrogel extract, with cells cultured alone as blank control, and cell viability was detected by live/dead cell staining. RESULTS AND CONCLUSION: The inhibition zone experiment showed that the antibacterial properties of 60 and 80 μg/mL QuAgNPs/HAMA hydrogels were stronger than those of 1, 5, 10, 20, 40 μg/mL QuAgNPs/HAMA hydrogels, and there was no difference between 60 and 80 μg/mL QuAgNPs/HAMA hydrogels. Both 60 and 80 μg/mL QuAgNPs/HAMA hydrogels had good in vitro drug release properties. Therefore, 60 μg/mL QuAgNPs/HAMA hydrogel was selected for subsequent experiments. Scanning electron microscopy showed that HAMA hydrogel had a loose porous structure, and approximately spherical QuAgNPs particles were scattered on the surface of 60 μg/mL QuAgNPs/HAMA hydrogel. Spread plate antibacterial experiment showed that QuAgNPs and 60 μg/mL QuAgNPs/HAMA hydrogel had significant inhibitory effects on Staphylococcus aureus and Escherichia coli. Live/dead cell staining showed that QuAgNPs, HAMA hydrogel, and 60 μg/mL QuAgNPs/HAMA hydrogel did not affect cell viability and had good cytocompatibility. These results indicate that QuAgNPs/HAMA composite hydrogel has good antibacterial properties.

1. Introduction

The skin is the largest barrier organ of the human body. When the skin is damaged due to trauma, surgery, disease, etc., external bacteria can easily invade and cause infection, forming an 'infected wound' [1-2]. Such wounds not only delay the healing process but may also lead to serious complications such as local tissue necrosis and systemic infection, making them one of the common clinical skin problems [3]. Methacrylated hyaluronic acid (HAMA) hydrogel is a derivative of hyaluronic acid, a key component of the extracellular matrix, widely distributed in various human tissues [4]. This hydrogel can maintain a moist healing environment for wounds, which is conducive to promoting cell migration and proliferation, and can also serve as a drug carrier to achieve controlled release of therapeutic components [5-6]. Silver nanoparticles (AgNPs) possess broad-spectrum antibacterial efficacy and can effectively inhibit common skin infection pathogens such as Staphylococcus aureus and Escherichia coli [7-8]. Quercetin is a natural flavonoid compound with various biological activities such as anti-inflammatory, antioxidant, and promotion of cell repair. Multiple studies have confirmed that quercetin can inhibit the release of inflammatory factors and reduce local inflammatory responses in wounds, creating favorable conditions for wound healing [9-10]. However, quercetin has poor water solubility and low bioavailability, which limits its application in wound treatment [11].

Currently, many types of nanocarriers and tissue-specific designs have been developed to address these challenges. The combination of quercetin with silver nanoparticles not only improves the stability and dispersibility of silver nanoparticles but also reduces the release of silver ions, thereby decreasing potential toxicity to cells and tissues. This study aims to investigate the antibacterial properties of quercetin-silver nanoparticle/HAMA composite hydrogels, providing a new direction for the development of composite antibacterial materials for infected wound treatment.