Treating large bone defects is often a challenge for medical science. If the defect becomes infected, treatment becomes even more difficult. There have been research efforts to find both materials which enhance bone regeneration and materials with antimicrobial effects. However, there are few studies on substances which combine these two properties.

Malcolm Xing, University of Manitoba, Winnipeg, Canada, Quan Yuan, Sichuan University, Chengdu, China, and colleagues have developed and tested a hydrogel containing nanosilver and nanosilica designed to treat infected bone defects. The team first synthesized a biodegradable crosslinker, poly(amidoamine) (PAA). They copolymerized this crosslinker with poly(ethylene glycol) diacrylate (PEGDA) to fabricate a PEGDA−PAA hydrogel system. The team added nanosilver and nanosilica (nAg/nSiO₂) particles to the hydrogel to form the final composite material.

The team characterized the material using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray energy-dispersive spectroscopy (EDS) analysis. The researchers found pore sizes of about 50−100 μm in the composite, suitable for supplying cells with nutrients.

The silver nanoparticles have an antimicrobial effect that helps to combat infections. The researchers tested the material’s antibacterial properties in vitro and found that it inhibited the growth of both Gram-positive and Gram-negative bacteria. They also tested the composite as a treatment for infected bone defects in rats. After implanting the material, indicators of ongoing infections decreased significantly, while new bone formation was improved compared to an untreated control group.

• A Novel Nanosilver/Nanosilica Hydrogel for Bone Regeneration in Infected Bone Defects,
  Shiwen Zhang, Yuchen Guo, Yuliang Dong, Yunshu Wu, Lei Cheng, Yongyue Wang, Malcolm Xing, Quan Yuan,
  ACS Appl. Mater. Interfaces 2016.
  DOI: 10.1021/acsami.6b01432