Silver and copper addition enhances the antimicrobial activity of calcium hydroxide coatings on titanium

Surface Modification of Titanium Implants by Metal Ions and Nanoparticles for Biomedical Application

Implant surface modification can improve osseointegration and reduce peri-implant inflammation. Implant surfaces are modified with metals because of their excellent mechanical properties and significant functions. Metal surface modification is divided into metal ions and nanoparticle surface modification. These two methods function by adding a finishing metal to the surface of the implant, and both play a role in promoting osteogenic, angiogenic, and antibacterial properties. Based on this, the nanostructural surface changes confer stronger antibacterial and cellular affinity to the implant surface. The current paper reviews the forms, mechanisms, and applications of nanoparticles and metal ion modifications to provide a foundation for the surface modification of implants.

Antibacterial approaches in tissue engineering using metal ions and nanoparticles: From mechanisms to applications

Bacterial infection of implanted scaffolds may have fatal consequences and, in combination with the emergence of multidrug bacterial resistance, the development of advanced antibacterial biomaterials and constructs is of great interest. Since decades ago, metals and their ions had been used to minimize bacterial infection risk and, more recently, metal-based nanomaterials, with improved antimicrobial properties, have been advocated as a novel and tunable alternative. A comprehensive review is provided on how metal ions and ion nanoparticles have the potential to decrease or eliminate unwanted bacteria. Antibacterial mechanisms such as oxidative stress induction, ion release and disruption of biomolecules are currently well accepted. However, the exact antimicrobial mechanisms of the discussed metal compounds remain poorly understood. The combination of different metal ions and surface decorations of nanoparticles will lead to synergistic effects and improved microbial killing, and allow to mitigate potential side effects to the host. Starting with a general overview of antibacterial mechanisms, we subsequently focus on specific metal ions such as silver, zinc, copper, iron and gold, and outline their distinct modes of action. Finally, we discuss the use of these metal ions and nanoparticles in tissue engineering to prevent implant failure.

Osteoclast and osteoblast response to strontium-doped struvite coatings on titanium for improved bone integration

To develop implants with improved bone ingrowth, titanium substrates were coated with homogeneous and dense struvite (MgNH4PO4·6H2O) layers by means of electrochemically assisted deposition. Strontium nitrate was added to the coating electrolyte in various concentrations, in order to fabricate Sr-doped struvite coatings with Sr loading ranging from 10.6 to 115 μg/cm2. It was expected and observed that osteoclast activity surrounding the implant was inhibited. The cytocompatibility of the coatings and the effect of Sr-ions in different concentrations on osteoclast formation were analyzed in vitro. Osteoclast differentiation was elucidated on morphological, biochemical as well as on gene expression level. It could be shown that moderate concentrations of Sr2+ had an inhibitory effect on osteoclast formation, while the growth of osteoblastic cells was not negatively influenced compared to pure struvite surfaces. In summary, the electrochemically deposited Sr-doped struvite coatings are a promising approach to improve bone implant ingrowth.

Silver release of Ag (I) doped hydroxyapatite: In vitro study

A material is produced by doping of silver (Ag (I)) which has antibacterial property to nano hydroxyapatite (nHAp), to remove the hipersensitivity in the teeth by closing the dentine tubules or dental micro cracks of the teeth and effective against for some bacteria. The doping of Ag (I) can also produces a toxic effect. Ag (I) can be released from the structure as a result of biological, physical and chemical effects and may cause toxicity. Therefore, it is important to determine whether the presence of Ag (I) has a toxic effect. In this study, Ag (I)-doped nHAp was synthesized by precipitation method and tried to determine the release values as a function of time compared to the doping rate by using the ICP-OES. Also, the products we produce in simulated body fluid were kept for retention periods of 4-20 weeks to determine degradation percentages. A cytotoxicity study was performed to observe the toxic effect that may be caused by possible Ag (I) release. According to the analysis, the release values in all products were observed in ppb level. And it is concluded that the materials produced are not degraded. Cell viability values of more than 70% were obtained. It was observed that the release of Ag (I) bound to Ag (I)-doped nHAp hexagonal structure was very low. It was concluded that the products are not degraded and Ag (I)-doped nHAp to a certain ratio is a biocompatible material that can be used in dentistry for treatment.