Recent progress in surface modification of metals coated by plasma electrolytic oxidation: Principle, structure, and performance

Tissue engineering endeavors to regenerate tissues and organs through appropriate cellular and molecular interactions at biological interfaces. To this aim, bio-mimicking scaffolds have been designed and practiced to regenerate and repair dysfunctional tissues by modifying cellular activity. Cellular activity and intracellular signaling are performances given to a tissue as a result of the function of elaborated electrically conductive materials. In some cases, conductive materials have exhibited antibacterial properties; moreover, such materials can be utilized for on-demand drug release. Various types of materials ranging from polymers to ceramics and metals have been utilized as parts of conductive tissue engineering scaffolds, having conductivity assortments from a range of semi-conductive to conductive. The cellular and molecular activity can also be affected by the microstructure; therefore, the fabrication methods should be evaluated along with an appropriate selection of conductive materials. This review aims to address the research progress toward the use of electrically conductive materials for the modulation of cellular response at the material-tissue interface for tissue engineering applications.

https://www.mdpi.com/2218-273X/9/9/448/pdf

Electrically Conductive Materials: Opportunities and Challenges in Tissue Engineering

MgO/ZnO composite coatings were successfully prepared on AZ91 Mg alloy by plasma electrolytic oxidation (PEO) method using electrolytes containing ZnO nanoparticles (NPs) to extend their biomedical applications. The effect of the concentration of 0 to 4.5 g·L−1 ZnO NPs in phosphate-based electrolyte on the microstructure, composition, physical features, corrosion and biodegradation properties of coatings was investigated. Observing the microstructure through field emission scanning electron microscopy (FESEM) confirmed that ZnO NPs were well up-taken in the coating structure with crater-like morphology and, they were mostly accumulated near the pores. As ZnO NPs concentration increased, more particles were incorporated in the coating; however, porosity, thickness and surface roughness reduced. The evaluation of the electrochemical behavior of specimens using potentiodynamic polarization test revealed that the polarization resistance of the samples increased from 9.26 to 683.2 kΩ·cm2 by adding 4.5 g·L−1 ZnO NPs. The study of corrosion mechanism by identifying the coating features using electrochemical impedance spectroscopy (EIS) indicated that the compacting of the coating and the difficulty of the penetration path of corrosive ions between the coating layers due to the presence of ZnO NPs had a more dominant effect relative to thickness reduction. Conducting the bioactivity test by immersion of coatings in simulated body fluid (SBF) solution for 14 days showed the higher growth of calcium phosphate layer formed on the sample as the concentration of ZnO NPs increases. In addition, the changes in weight loss and volume of hydrogen evolution were much less, and the mechanism of these changes was presented.

Enhanced corrosion resistance and in-vitro biodegradation of plasma electrolytic oxidation coatings prepared on AZ91 Mg alloy using ZnO nanoparticles-incorporated electrolyte

Corrosion resistance and biocompatibility of calcium-containing coatings developed in near-neutral solutions containing phytic acid and phosphoric acid on AZ31B alloy

Surface characterization and corrosion behavior of calcium phosphate (Ca-P) base composite layer on Mg and its alloys using plasma electrolytic oxidation (PEO): A review

Electrophoretic deposition of graphene oxide on plasma electrolytic oxidized-magnesium implants for bone tissue engineering applications

Improving corrosion behavior and in vitro bioactivity of plasma electrolytic oxidized AZ91 magnesium alloy using calcium fluoride containing electrolyte

The competitive mechanism of plasma electrolyte oxidation for the formation of magnesium oxide bioceramic coatings

Comparison of corrosion and antibacterial properties of Al alloy treated by plasma electrolytic oxidation and anodizing methods

Conjugated polymers such as polyaniline (PANI) and polypyrrole (PPy) nanotubes are favorable materials for various applications from electronics to medicine, because of their wide range of conductivity, reasonable cost, processability, and effortlessness of their synthesis. Conducting polymers such as doped polyacetylene, polythiophene, and PANI have been subjects of active research for many years. PANI and its composites revealed suitable electrical properties as well as synthesis simplicity to be distinguished among the conducting family of polymers, so that their low percolation threshold in miscible blends was particularly noticeable. By manipulating polymerization parameters such as temperature, oxidant content, the media, and polymerization route it is possible to obtain conducting polymers having a wide range of properties. The 3-omega method has become a readily accepted technique to directly measure the thermal conductivity of thin films of conducting polymers. The morphology, concentration, and mixing mode of PANI composites were also found to have an impact on the conductivity. In this chapter, methods applied in measuring the thermal and electrical conductivity of PANI are comprehensively reviewed.

Aidin Bordbar Khiabani

Papers

Electrophoretic deposition of graphene oxide on plasma electrolytic oxidized-magnesium implants for bone tissue engineering applications

Improving corrosion behavior and in vitro bioactivity of plasma electrolytic oxidized AZ91 magnesium alloy using calcium fluoride containing electrolyte

The competitive mechanism of plasma electrolyte oxidation for the formation of magnesium oxide bioceramic coatings

Comparison of corrosion and antibacterial properties of Al alloy treated by plasma electrolytic oxidation and anodizing methods

Experimental procedures for assessing electrical and thermal conductivity of polyaniline