1.
Antibacterial Titanium Implants Biofunctionalized by Plasma Electrolytic Oxidation with Silver, Zinc, and Copper: A Systematic Review.
van Hengel, IAJ, Tierolf, MWAM, Fratila-Apachitei, LE, Apachitei, I, Zadpoor, AA
International journal of molecular sciences. 2021;(7)
Abstract
Patients receiving orthopedic implants are at risk of implant-associated infections (IAI). A growing number of antibiotic-resistant bacteria threaten to hamper the treatment of IAI. The focus has, therefore, shifted towards the development of implants with intrinsic antibacterial activity to prevent the occurrence of infection. The use of Ag, Cu, and Zn has gained momentum as these elements display strong antibacterial behavior and target a wide spectrum of bacteria. In order to incorporate these elements into the surface of titanium-based bone implants, plasma electrolytic oxidation (PEO) has been widely investigated as a single-step process that can biofunctionalize these (highly porous) implant surfaces. Here, we present a systematic review of the studies published between 2009 until 2020 on the biomaterial properties, antibacterial behavior, and biocompatibility of titanium implants biofunctionalized by PEO using Ag, Cu, and Zn. We observed that 100% of surfaces bearing Ag (Ag-surfaces), 93% of surfaces bearing Cu (Cu-surfaces), 73% of surfaces bearing Zn (Zn-surfaces), and 100% of surfaces combining Ag, Cu, and Zn resulted in a significant (i.e., >50%) reduction of bacterial load, while 13% of Ag-surfaces, 10% of Cu-surfaces, and none of Zn or combined Ag, Cu, and Zn surfaces reported cytotoxicity against osteoblasts, stem cells, and immune cells. A majority of the studies investigated the antibacterial activity against S. aureus. Important areas for future research include the biofunctionalization of additively manufactured porous implants and surfaces combining Ag, Cu, and Zn. Furthermore, the antibacterial activity of such implants should be determined in assays focused on prevention, rather than the treatment of IAIs. These implants should be tested using appropriate in vivo bone infection models capable of assessing whether titanium implants biofunctionalized by PEO with Ag, Cu, and Zn can contribute to protect patients against IAI.
2.
Ultrasensitive sandwich-type photoelectrochemical immunosensor based on CdSe sensitized La-TiO2 matrix and signal amplification of polystyrene@Ab2 composites.
Fan, D, Ren, X, Wang, H, Wu, D, Zhao, D, Chen, Y, Wei, Q, Du, B
Biosensors & bioelectronics. 2017;:593-599
Abstract
A novel and sensitive sandwich-type photoelectrochemical (PEC) sensor was fabricated using signal amplification strategy for the quantitative detection of the prostate specific antigen (PSA). CdSe nanoparticles (NPs) sensitized lanthanum-doped titanium dioxide (La-TiO2) composites were used to bind the primary antibodies (Ab1). The doping of lanthanum promoted the visible light absorption of TiO2 and remarkably enhanced the photocurrent. Moreover, 0.3%La-TiO2 displayed the highest photocurrent in the La-TiO2 composites, which was twice as much as that of undoped TiO2. Carboxyl modified CdSe NPs were assembled onto La-TiO2 composites via the dentate binding between -COOH and Ti atom in TiO2 NPs, which dramatically promoted the photocurrent intensity by approximately 2.1 times. Carboxyl functionalized polystyrene (PS) microspheres were coated with the secondary antibodies (Ab2). Owing to the better insulation property and steric hindrance of the prepared polystyrene@Ab2 (PS@Ab2) composites, the significant reduction of the photocurrent signal was achieved after the specific immune recognition. Under the optimum experimental conditions, the fabricated PEC sensor realized ultrasensitive detection of PSA in the range of 0.05-100pgmL-1 with a detection limit of 17fgmL-1. Moreover, this well-designed PEC immunoassay exhibited ideal reproducibility, stability, and selectivity, which is a promising platform for the detection of other important tumor targets.
3.
Effect of topical fluoride application on titanium alloys: a review of effects and clinical implications.
Fragou, S, Eliades, T
Pediatric dentistry. 2010;(2):99-105
Abstract
The purposes of this review were to: summarize the currently available evidence on the effect of fluoride on titanium alloys; discuss the mechanisms involved; and assess the clinical relevance and validity of statements deriving from in vitro approaches. The spectrum of effects noted include: morphological variations, such as increased roughness with adverse effects on sliding mechanics; mechanical properties of the wires, which may entail effects on the superelastic plateau of nickel-titanium wires, or reduction in the strength of wires, which can result in frequent intraoral failures; and release of ions during service. Reduced nickel release rates have been documented, however, from retrieved nickel-titanium wires presumably due to the passive layer formed. In relevant research, forming oxide on titanium alloys has been proposed to provide immunity to further degradation and ionic release, since nickel ions must diffuse through this layer to be released. The described evidence of fluoride on titanium alloys derives mostly from in vitro research, which includes oversimplifications in simulating the oral environment. The reactivity in laboratory experiments is dramatically increased relative to the actual clinical conditions, which exaggerates the effects noted. The effects shown have not been validated in vivo, since the only available evidence on intraorally fractured nickel-titanium archwires did not support the implication of hydrogen embrittlement as a failure mechanism. Rather, fractures were found to be related to: (1) mechanical factors associated with loading of the wire in specific arch sites; and (2) the masticatory forces. Clinically, the use of fluoride varnishes at specific, caries-risk sites may provide protection while minimizing the potential risk of adverse effects.