Biofilms are a complex group of microbial cells that adhere to the exopolysaccharide matrix present on the surface of medical devices. Biofilm-associated infections in the medical devices pose a serious problem to the public health and adversely affect the function of the device. Medical implants used in oral and orthopedic surgery are fabricated using alloys such as stainless steel and titanium. The biological behavior, such as osseointegration and its antibacterial activity, essentially depends on both the chemical composition and the morphology of the surface of the device. Surface treatment of medical implants by various physical and chemical techniques are attempted in order to improve their surface properties so as to facilitate bio-integration and prevent bacterial adhesion. The potential source of infection of the surrounding tissue and antimicrobial strategies are from bacteria adherent to or in a biofilm on the implant which should prevent both biofilm formation and tissue colonization. This article provides an overview of bacterial biofilm formation and methods adopted for the inhibition of bacterial adhesion on medical implants.
Ceramic oxides such as alumina and zirconia are used to fabricate dental and orthopedic implants. However, their usage is limited as they fail due to low fracture toughness. To overcome this issue, ceramic coatings on metallic implants is attempted to have a combined effect of ceramics and metallic materials. This paper reports on the microstructure, phase analysis, mechanical properties, osseointegration and antibacterial activity of three different wear-resistant coatings developed on Ti-6Al-4V alloy which is used widely as orthopedic and dental implants. The powders of following compositions, i. Nanostructured Al2O3 + 13 wt% TiO2/μ-TiO2 BL coating (S1), ii. μ-Al2O3 + 13 wt% nanostructured TiO2/μ-TiO2 BL coating (S2), iii. Nanostructured Al2O3 + 13 wt% TiO2/μ-YSZ BL coating (S3), were sprayed using atmospheric plasma spray process onto Ti-6Al-4V alloy. The coatings were characterized using X-ray diffraction (XRD), Scanning electron microscope (SEM), Profilometer and gonieometer to determine their phases, microstructure, surface roughness and contact angle. In addition, micro indentation hardness and scratch resistance were also evaluated. Amongst the three coatings, S2 exhibited higher hardness value with higher scratch resistance. The antibacterial activity was studied using colony formation on all three coatings. The antibacterial efficiency of S1 as well as S3 coatings was higher as seen from less number of bacterial colonies on the surface. The results of in-vitro studies on the biocompatibility of nano/micron alumina and zirconia ceramic coatings which were analyzed with hMSC's, reveals that S1 is cytotoxic with less number of cell attachment when compared to S2 and S3.
Zirconia has its place in the biomedical industry because of its mechanical strength, bio-inertness, and physiochemical properties. Zirconia was synthesized and doped with Terbium (Tb), a lanthanide that was reported to show a photoluminescence property, which was a major characteristic for carcinogenic studies. Zirconia and Tb doped Zirconia were synthesized using the co-precipitation technique and were sintered at a temperature ranging from 900 to 1200 °C. The Zirconia sample and Tb doped Zirconia were thus studied for structural diversities using the X-ray powder diffraction technique (XRD), FTIR, FE-SEM, and TEM. From XRD, Zirconia phase transformation from monoclinic to tetragonal phase was observed, which signified limited fracture, elasticity, and crack formation. It was evident that Terbium stabilized the tetragonal phase of Zirconia, which reportedly shows mechanical properties, which include fracture toughness and flexural strength. The particle size of the Zirconia was comparatively more than the Tb doped Zirconia. The particle size of Zirconia ranged between 176 nm and 393 nm and the particle size of Tb doped Zirconia ranged between 110 nm and 343 nm. The biocompatibility of both the samples was tested using an Mg-63 cell line, and the cell viability was observed to be higher in Tb doped Zirconia when compared to the undoped Zirconia sample.
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