Poster Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

A nanocomposite hydrogel for bone regeneration and antimicrobial efficacy - A dental perspective (#325)

Dawn E Coates 1 , Dina Abdelmoneim 1 , KC Li 1 , Warwick J Duncan 1
  1. Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand

Aim

Bone regenerative constructs are a common clinical indication for tooth loss and socket preservation, periodontitis, peri-implantitis, cancer and injury. The aim of this research is to produce, and then investigate both in vitro and in vivo, a novel antimicrobial bone regenerative construct for dental and orthopaedic applications.

Methods

Lipoic-capped AgNPs were synthesised and assessed by DLS. GelMA was synthesised and crosslinked with 0.5mM Ru, 5mM SPS, and visible light (30mW/cm). AgNPs were incorporated at 0-200 µg/mL (n=3; 9-doses). EDS assessed retention of nanoparticles within HyStem®-C, GelMA and PVA crosslinked with LAP, Ru/SPS or I2959.  Human gingival fibroblasts were seeded in hydrogels at 5 million cells/mL and metabolic activity and live/dead staining quantitated. Antimicrobial assays included MICs, MBCs and a disc diffusion with E. coli and S. aureus. The constructs were assessed by FTIR-ATR, ICP-MS and TEM. The rabbit cranial model was conducted with 6mm osteotomy defects and sites treated as empty, BioOss®, GelMA or GelMA/AgNPs (n=6); with quantification by µCT and resin embedding at 4- and 16-weeks post-surgery.

Results

AgNPs (1–12nm) were encapsulated in GelMA, HyStem®-C and PVA. EDS revealed that only with GelMA+Ru/SPS were the AgNPs stable. They were antimicrobial at concentrations of ≥5 µg/mL. TEM revealed aggregation of AgNPs in HyStem®-C while in GelMA particles were evenly dispersed. FTIR-ATR showed shifts in -hydroxyl and -amide peaks when AgNPs were added to GelMA. Cytotoxicity was satisfactory. Defects within the rabbit cranial model treated with GelMA/AgNPs (100 µg/mL) showed no adverse inflammatory response, with new bone regeneration being better than empty defects and similar to BioOss®.

Conclusion

Lipoic-capped AgNPs provide broad spectrum anti-bacterial and anti-inflammatory functions. Our patented GelMA/AgNPs construct is a light cross-linkable hydrogel with antimicrobial effect which resulted in repair of cranial defects in vivo and complete remodelling of the defect, offering advantages over BioOss®.