Strontium incorporation to optimize the antibacterial and biological characteristics of silver-substituted hydroxyapatite coating

Biomimetic Coprecipitation of Silk Fibrin and Calcium Phosphate: Influence of Selenite Ions

Large bone defect creates an urgent need for osteogenic biomaterials. However, bone nonunion and infection are choke points in the therapy of this disease. How to recruit the mesenchymal stem cells to defect sites and increase the cell viability are the critical processes. One effective method was the fabrication of biomimetic silk fibrin/selenium-doped hydroxyapatite (SF/HASe) material, which could create a niche for cell proliferation. So, the aim of the present study was to seek a facile route to prepare this biocomposites and investigate the osteogenic capability. Results showed that the biomimetic coprecipitation was a successful route to prepare SF/HASe biocomposites, which presented higher cell proliferation activity and better modulation of the selenite release during incubation in biological medium. Besides, the biocomposites exhibited weird and porous pot morphology. Such features could provide large surface area for the cells and proteins to attach. Silk fibrin, adhered onto the surface of hydroxyapatite (HA) crystals, plays a crucial impact on the release profile of selenite ions. The release behavior of the selenite ions exhibited stably slow release fashion. Therefore, it is feasible to employ SF/HASe biocomposites to repair bone defects and apply into the therapy of osteosarcoma postoperatively.

Recent coating developments for combination devices in orthopedic and dental applications: A literature review

Orthopedic and dental implants have been used successfully for decades to replace or repair missing or damaged bones, joints, and teeth, thereby restoring patient function subsequent to disease or injury. However, although device success rates are generally high, patient outcomes are sometimes compromised due to device-related problems such as insufficient integration, local tissue inflammation, and infection. Many different types of surface coatings have been developed to address these shortcomings, including those that incorporate therapeutic agents to provide localized delivery to the surgical site. While these coatings hold enormous potential for improving device function, the list of requirements that an ideal combination coating must fulfill is extensive, and no single coating system today simultaneously addresses all of the criteria. Some of the primary challenges related to current coatings are non-optimal release kinetics, which most often are too rapid, the potential for inducing antibiotic resistance in target organisms, high susceptibility to mechanical abrasion and delamination, toxicity, difficult and expensive regulatory approval pathways, and high manufacturing costs. This review provides a survey of the most recent developments in the field, i.e., those published in the last 2-3years, with a particular focus on technologies that have potential for overcoming the most significant challenges facing therapeutically-loaded coatings. It is concluded that the ideal coating remains an unrealized target, but that advances in the field and emerging technologies are bringing it closer to reality. The significant amount of research currently being conducted in the field provides a level of optimism that many functional combination coatings will ultimately transition into clinical practice, significantly improving patient outcomes.

Physico-mechanical properties of Mg and Ag doped hydroxyapatite/chitosan biocomposites

Co-Substituted hydroxyapatite Mg–Ag-HAP/chitosan biocomposites were synthesized successfully using a simple chemical method, and the compressive strength progressed up to 15.2 MPa atx= 0.8.

An effective treatment of experimental osteomyelitis using the antimicrobial titanium/silver-containing nHP66 (nano-hydroxyapatite/polyamide-66) nanoscaffold biomaterials

Effective treatment of osteomyelitis remains a formidable clinical challenge. The rapid emergence of multidrug-resistant bacteria has renewed interest in developing antimicrobial biomaterials using antiseptic silver ions to treat osteomyelitis. However, inadequate local retention and severe cytotoxic effects have limited the clinical use of ionic silver for bone grafts. We recently developed novel porous nano-hydroxyapatite/polyamide 66 (nHP66)-based nanoscaffold materials containing varied concentrations of silver ions (Ag⁺) (TA-nHAPA66) and oxidized titanium (TiO₂), which was added as a second binary element to enhance antibacterial activity and biocompatibility. In this study, we establish a large cohort of rabbit model of experimental osteomyelitis and investigate the in vivo antimicrobial and therapeutic effects of TA-nHP66 biomaterials and their in vivo silver release kinetics. We find the TA-nHP66 scaffolds exhibit potent antibacterial activities against E. coli and S. aureus, support cell adhesion and cell proliferation of pre-osteoblasts, and stimulate osteogenic regulator/marker expression. Moreover, the TA2-nHP66 scaffold exerts potent antibacterial/anti-inflammation effects in vivo and promotes bone formation at the lesion site of osteomyelitis. We further demonstrate that TA2-nHP66 exhibits excellent biosafety profile without apparent systemic toxicities. Therefore, the TA-nHP66 scaffold biomaterials may be further explored as an effective adjuvant therapy for infected bone defects and/or osteomyelitis debridement.

Immobilizing bacitracin on titanium for prophylaxis of infections and for improving osteoinductivity: An in vivo study

Bacitracin immobilized on the titanium (Ti) surface significantly improves anti-bacterial activity and biocompatibility in vitro. In the current study, we investigated the biologic performance (bactericidal effect and bone-implant integration) of bacitracin-modified Ti in vivo. A rat osteomyelitis model with femoral medullary cavity placement of Ti rods was employed to analyze the prophylactic effect of bacitracin-modified Ti (Ti-BC). Thirty-six female Sprague Dawley (SD) rats were used to establish the Ti implant-associated infection. The Ti and Ti-BC rods were incubated with and without Staphylococcus aureus to mimic the contaminated Ti rod and were implanted into the medullary cavity of the left femur, and sterile Ti rods were used as the blank control. After 3 weeks, the bone pathology was evaluated using X-ray and micro-computed tomography (micro-CT) analysis. For the investigation of the Ti-BC implant osseointegration in vivo, fifteen SD rats were divided into three groups (N=5), namely Ti, Ti-dopamine immobilized (Ti-DOPA), and Ti-BC. Ti rods were implanted into the left femoral cavity and micro-CT and histological evaluation was conducted after 12 weeks. The in vivo study indicated that Ti-immobilized bacitracin owned the prophylaxis potential for the infection associated with the Ti implants and allowed for the osseointegration. Thus, the multiple biofunctionalized Ti implants could be realized via immobilization of bacitracin, making them promising candidates for preventing the Ti implant-associated infections while retaining the osseointegration effects.

An Injectable Hydrogel as Bone Graft Material with Added Antimicrobial Properties

Currently, the technique which provides the best chances for a successful bone graft, is the use of bone tissue from the same patient receiving it (autograft); the main limitations are the limited availability and the risks involved in removing living bone tissue, for example, explant site pain and morbidity. Allografts and xenografts may overcome these limitations; however, they increase the risk of rejection. For all these reasons the development of an artificial bone graft material is particularly important and hydrogels are a promising alternative for bone regeneration. Gels were prepared using 1,4-butanediol diacrylate as crosslinker and alpha tricalciumphosphate; ZnCl₂ and SrCl₂ were added to the aqueous phase. MTT results demonstrated that the addition of strontium had a beneficial effect on the osteoblast cells density on hydrogels, and zinc instead did not increase osteoblast proliferation. The amount of calcium produced by the osteoblast cells quantified through the Alizarin Red protocol revealed that both strontium and zinc positively influenced the formation of calcium; furthermore, their effect was synergistic. Rheology properties were used to mechanically characterize the hydrogels and especially the influence of crosslinker's concentration on them, showing the hydrogels presented had extremely good mechanical properties. Furthermore, the antimicrobial activity of strontium and zinc in the hydrogels against methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis was determined.

Ag-Incorporated FHA Coating on Pure Mg: Degradation and in Vitro Antibacterial Properties

Fluoridated hydroxyapatite (FHA) coating can help retard the degradation of magnesium, and possess good biocompatibility. However, the antibacterial property of FHA is very limited. In this work, we aimed to incorporate silver into FHA structure to fabricate biocompatible and antibacterial coatings with enhanced anticorrosion property. The results showed that the Ag-FHA coating prepared by electrochemical deposition and subsequent immersion in AgNO3 solution was superior to the Ag-FHA coating prepared by coelectrodeposition in terms of crystal structure, surface morphology and corrosion resistance. The release of Ag(+) ion causing high antiplanktonic bacterial rate and excellent antiadherence property to MRSA. Meanwhile, good cell compatibility of MC3T3-E1 including cell viability, cell adhesion, and cell morphology was achieved under the controlled degradation. The balance of degradation and antimicrobial property of Ag-incorporated FHA coating made it an alternative in the application of surface modification for biodegradable Mg.

Dual functional polylactide–hydroxyapatite nanocomposites for bone regeneration with nano-silver being loaded via reductive polydopamine

In bone tissue engineering, scaffolding materials with antibacterial function are required to avoid failure in treating infected bone defects, and poly(l-lactide) - hydroxyapatite nanocomposites containing silver nanoparticles are good choices for the purpose.