Biomedical Grade Stainless Steel Coating of Polycaffeic Acid via Combined Oxidative and Ultraviolet Light-Assisted Polymerization Process for Bioactive Implant Application

Biomedical Alloys and Physical Surface Modifications: A Mini-Review

Biomedical alloys are essential parts of modern biomedical applications. However, they cannot satisfy the increasing requirements for large-scale production owing to the degradation of metals. Physical surface modification could be an effective way to enhance their biofunctionality. The main goal of this review is to emphasize the importance of the physical surface modification of biomedical alloys. In this review, we compare the properties of several common biomedical alloys, including stainless steel, Co-Cr, and Ti alloys. Then, we introduce the principle and applications of some popular physical surface modifications, such as thermal spraying, glow discharge plasma, ion implantation, ultrasonic nanocrystal surface modification, and physical vapor deposition. The importance of physical surface modifications in improving the biofunctionality of biomedical alloys is revealed. Future studies could focus on the development of novel coating materials and the integration of various approaches.

Ag-Based Synergistic Antimicrobial Composites. A Critical Review

The emerging problem of the antibiotic resistance development and the consequences that the health, food and other sectors face stimulate researchers to find safe and effective alternative methods to fight antimicrobial resistance (AMR) and biofilm formation. One of the most promising and efficient groups of materials known for robust antimicrobial performance is noble metal nanoparticles. Notably, silver nanoparticles (AgNPs) have been already widely investigated and applied as antimicrobial agents. However, it has been proposed to create synergistic composites, because pathogens can find their way to develop resistance against metal nanophases; therefore, it could be important to strengthen and secure their antipathogen potency. These complex materials are comprised of individual components with intrinsic antimicrobial action against a wide range of pathogens. One part consists of inorganic AgNPs, and the other, of active organic molecules with pronounced germicidal effects: both phases complement each other, and the effect might just be the sum of the individual effects, or it can be reinforced by the simultaneous application. Many organic molecules have been proposed as potential candidates and successfully united with inorganic counterparts: polysaccharides, with chitosan being the most used component; phenols and organic acids; and peptides and other agents of animal and synthetic origin. In this review, we overview the available literature and critically discuss the findings, including the mechanisms of action, efficacy and application of the silver-based synergistic antimicrobial composites. Hence, we provide a structured summary of the current state of the research direction and give an opinion on perspectives on the development of hybrid Ag-based nanoantimicrobials (NAMs).

Phenol-Boronic surface functionalization of gold nanoparticles; to induce ROS damage while inhibiting the survival mechanisms of cancer cells

The natural phenolic molecule caffeic acid, show promising effects on biological systems as an anti/pro-oxidant, anti-cancer, and anti-inflammatory agent. In nanoparticle functionalization designs, most organic nanoparticle coatings are utilized only for their ability to carry chemotherapeutics and targeting ligand. In this study, UV-light and auto-oxidation polymerization of caffeic acid on top of as-prepared gold nanoparticles was utilized to bring about a 5 nm multifunctional coating. The resulting polycaffeic acid (PCA) coating was used to conjugate both boronic acid containing compounds, chemotherapeutic bortezomib (BTZ) and cancer targeting ligand folate, while inducing mitochondrial reactive oxygen species that can damage intracellular proteins and DNA. This complements the drug payload, bortezomib's cell survival inhibition properties. The drug, targeting ligand, and coating complexation are all pH cleavable under acidic pH condition (<5.0) which can be found in a tumor and endosomal microenvironment. The in vitro and in vivo experiments demonstrated cancer cytotoxicity and tumor inhibiting properties of the developed nanomedicine.

UV Light Assisted Coating Method of Polyphenol Caffeic Acid and Mediated Immobilization of Metallic Silver Particles for Antibacterial Implant Surface Modification

Titanium implants are extensively used in biomedical applications due to their excellent biocompatibility, corrosion resistance, and superb mechanical stability. In this work, we present the use of polycaffeic acid (PCA) to immobilize metallic silver on the surface of titanium materials to prevent implant bacterial infection. Caffeic acid is a plant-derived phenolic compound, rich in catechol moieties and it can form functional coatings using alkaline buffers and with UV irradiation. This combination can trigger oxidative polymerization and deposition on the surface of metallic substrates. Using PCA can also give advantages in bone implants in decreasing inflammation by decelerating macrophage and osteoclast activity. Here, chemical and physical properties were investigated using FE-SEM, EDS, XPS, AFM, and contact angle. The in vitro biocompatibility and antibacterial studies show that PCA with metallic silver can inhibit bacterial growth, and proliferation of MC-3T3 cells was observed. Therefore, our results suggest that the introduced approach can be considered as a potential method for functional implant coating application in the orthopedic field.