Mechanistic investigation on microbial toxicity of nano hydroxyapatite on implant associated pathogens

Fabrication of hydroxyapatite-based nano-gold and nano-silver-doped bioceramic bone grafts: Enhanced mechanostructure, cell viability, and nuclear abnormality properties

In this study, nano-gold (nAu) and nano-silver (nAg) were doped at the molar ratios of Molar5-Molar30 to the Hydroxyapatite (HAp)-based bioceramic bone graft synthesized by the sol-gel method. The effects of nAu and nAg on structural, mechanical, cell viability, and nuclear abnormality of the synthesized bioceramic grafts were evaluated. The chemical and morphological properties of the bone grafts after production were examined through XRD and SEM-EDX analyses and mechanical tests. To determine the biocompatibility of the bone grafts, cell viability tests were performed using human fibroblast cells. In the cytotoxicity analyses, only HAp and HAp-nAu5 grafts did not show toxicological properties at any concentration, while HAp-nAg5 among the nAg-containing grafts gave the best results at the 200-100 μg/mL concentrations and showed significant cytotoxicity in human fibroblast cells. The other nAu-containing grafts showed toxicological properties in the concentration range of 200-50 μg/mL and nAg-containing grafts in the concentration range of 200-100 μg/mL against the negative control. The micronucleus (MN) analyses showed that the lowest total MN and L (lobbed) amounts, while the lowest total N (notched) amount, was obtained from the only HAp graft. It was found that the nAg-doped bone grafts gave higher total MN, L, and N amounts compared to the nAu-doped bone grafts. Furthermore, while the mean nuclear abnormality (NA) values of all grafts gave close results, the highest values were again obtained from the nAg-doped bone grafts.

A trilogy antimicrobial strategy for multiple infections of orthopedic implants throughout their life cycle

Bacteria-associated infection represents one of the major threats for orthopedic implants failure during their life cycles. However, ordinary antimicrobial treatments usually failed to combat multiple waves of infections during arthroplasty and prosthesis revisions etc. As these incidents could easily introduce new microbial pathogens in/onto the implants. Herein, we demonstrate that an antimicrobial trilogy strategy incorporating a sophisticated multilayered coating system leveraging multiple ion exchange mechanisms and fine nanotopography tuning, could effectively eradicate bacterial infection at various stages of implantation. Early stage bacteriostatic effect was realized via nano-topological structure of top mineral coating. Antibacterial effect at intermediate stage was mediated by sustained release of zinc ions from doped CaP coating. Strong antibacterial potency was validated at 4 weeks post implantation via an implanted model in vivo. Finally, the underlying zinc titanate fiber network enabled a long-term contact and release effect of residual zinc, which maintained a strong antibacterial ability against both Staphylococcus aureus and Escherichia coli even after the removal of top layer coating. Moreover, sustained release of Sr2+ and Zn2+ during CaP coating degradation substantially promoted implant osseointegration even under an infectious environment by showing more peri-implant new bone formation and substantially improved bone-implant bonding strength.

[Research progress of nanomaterials in osteomyelitis treatment]

Objective

To review the related studies on the application of nanomaterials in the treatment of osteomyelitis, and to provide new ideas for the research and clinical treatment of osteomyelitis.

Methods

The literature about the treatment of osteomyelitis with nanomaterials at home and abroad in recent years was reviewed and analyzed.

Results

At present, surgical treatment and antibiotic application are the main treatment options for osteomyelitis. But there are many defects such as antibiotic resistance, residual bone defect, and low effective concentration of local drugs. The application of nanomaterials can make up for the above defects. In recent years, nanomaterials play an important role in the treatment of osteomyelitis by filling bone defects, establishing local drug delivery system, and self-antibacterial properties.

Conclusion

It will provide a new idea and an important research direction for the treatment of osteomyelitis to fully study the related characteristics of nanomaterials and select beneficial materials to make drug delivery system or substitute drugs.

Fabrication of Chitosan/PVA/GO/CuO patch for potential wound healing application

Wound healing is a common issue in our day to day life. Our immune system repairs the damaged tissue by itself and its a time-consuming process. The GO/CuO nanocomposite (NC) was synthesized through the sol-gel method. XRD, FT-IR, Raman, and TEM analysis were used to analysis the physico-chemical properties of the sample. The GO/CuO patches were prepared using chitosan (Cs)/poly vinyl alcohol (PVA) due to its biocompatibility and biodegradable nature. The obtained patches showed better antimicrobial and wound healing property than recently reported materials. The GO/CuO NC plays a major part in angiogenesis process and in the synthesis, stabilization of extracellular matrix skin proteins. Thus, GO/CuO NC enhance the wound healing mechanism by increasing cell proliferation, antimicrobial property and rapid initiation of inflammatory. Moreover, the antimicrobial activity of CuO, GO, GO/CuO and GO/CuO patch were tested against bacteria causing wound infections. Cs/PVA patch and Cs/PVA/GO/CuO patch were analyzed for swelling, evaporation and degradation behavior. Increase in cell viability and migration of NIH3t3 cells by NC patch shows a potential way for wound healing applications.

Sustained release of amoxicillin from hydroxyapatite nanocomposite for bone infections

Hydroxyapatite (HAP) is the main constituent of human bone and teeth. Hydroxyapatite nanoparticles are used for the treatment of various bone infections. Nanohydroxyapatite is a biocompatible material. It is used as a drug carrier for drugs and biomolecules for various diseases. Hydroxyapatite nanoparticles are made into nanocomposite with sodium alginate and polyvinyl alcohol. This nanocomposite is used for the sustained release of drugs. It is characterized by various characterization techniques like XRD, FTIR, TEM, and Raman. Hydroxyapatite nanoparticles are coated initially with polyvinyl alcohol and then coated with sodium alginate. Amoxicillin is used as the model drug. Studies on the drug loading and drug release have been done. The release of the drug is sustained for about 30 days. Antimicrobial studies have shown good activity against pathogens. The zone of inhibition is found to be 18 mm for a concentration of 500 µg against Bacillus subtilis and 16 µg against Klebsiella pneumonia.

Coatings as the useful drug delivery system for the prevention of implant-related infections

Implant-related infections (IRIs) which led to a large amount of medical expenditure were caused by bacteria and fungi that involve the implants in the operation or in ward. Traditional treatments of IRIs were comprised of repeated radical debridement, replacement of internal fixators, and intravenous antibiotics. It needed a long time and numbers of surgeries to cure, which meant a catastrophe to patients. So how to prevent it was more important than to cure it. As an excellent local release system, coating is a good idea by its local drug infusion and barrier effect on resisting biofilms which were the main cause of IRIs. So in this review, materials used for coatings and evidences of prevention were elaborated.