Biological response of hydrogels embedding gold nanoparticles

Area of Science:

• Biomaterials Science
• Nanotechnology
• Cell Biology

Background:

• Development of novel nanocomposite hydrogels for biomedical applications.
• Evaluation of biological effects of gold nanoparticles integrated into polysaccharide hydrogels.

Purpose of the Study:

• To synthesize and characterize a nanocomposite hydrogel incorporating gold nanoparticles (AC-nAu).
• To assess the in vitro antimicrobial efficacy and cytotoxicity of AC-nAu hydrogels.
• To evaluate the in vivo biocompatibility and tissue response of AC-nAu hydrogels.

Main Methods:

• Preparation of AC-nAu nanocomposite hydrogels from natural polysaccharides and gold nanoparticles.
• In vitro antimicrobial assays against Staphylococcus aureus (Gram+) and Pseudomonas aeruginosa (Gram-).
• In vitro cytotoxicity assessment using LDH assays on HepG2 and MG63 cell lines.
• Apoptosis induction studies via cytofluorimetry and ROS level measurements.
• In vivo biocompatibility testing in a rat model, analyzing peri-implant soft tissue reactions.

Main Results:

• AC-nAu hydrogels demonstrated significant antimicrobial activity against both Gram-positive and Gram-negative bacteria.
• In vitro studies revealed cytotoxicity towards HepG2 and MG63 cells, mediated by apoptosis induction through increased intracellular ROS levels.
• In vivo evaluation showed a thicker fibrotic capsule (∼100 μm) around AC-nAu implants compared to silver-based hydrogels (∼50 μm) and controls (∼50 μm).

Conclusions:

• AC-nAu nanocomposite hydrogels exhibit potent antimicrobial properties but possess significant in vitro cytotoxicity.
• The observed apoptosis mechanism in eukaryotic cells is linked to elevated intracellular ROS.
• Silver-based hydrogels demonstrate superior biocompatibility in vivo compared to gold-based counterparts, indicated by reduced fibrotic capsule formation.