Glass-based coatings on biomedical implants: a state-of-the-art review

Abstract

Bioactive glasses, invented by Prof. Larry L. Hench in the late 1960s, have revolutionized the field of biomaterials as they were shown to tightly bond to both hard and soft living tissues and to stimulate cells towards a path of regeneration and self-repair. However, due to their relatively poor mechanical properties (brittleness, low bending strength and fracture toughness), they are generally unsuitable for load-bearing applications. On the other hand, bioactive glasses have been successfully applied as coatings on the surface of stronger/tougher substrates to combine adequate mechanical properties with high bioactivity and, in some cases, additional extrafunctionalities (e.g. antibacterial properties, drug release). After giving a short overview of the main issues concerning the fabrication of glass coatings, this review provides a state-of-the-art picture in the field and specifically discusses the development of bioactive and hierarchical coatings on 3D porous scaffolds, joint prostheses, metallic substrates (e.g. wires or nails) for orthopedic fixation, polymeric meshes and sutures for wound healing, ocular implants and percutaneous devices.

Processing methods for making porous bioactive glass‐based scaffolds—A state‐of‐the‐art review

“…EPD-assisted coating method was possible due to the presence of charged particles in the suspension. 88 In this way, multifunctional properties can be imparted to the porous substrate, namely apatite-forming ability 89 and controlled release of therapeutic agents (eg, strontium ions that can reduce bone resorption in osteoporotic patients). Slurry dipping proved to offer more control on the coating thickness and a better replication of the foam (Figure 7A), while EPD was prone to occlude some of the pores.…”

“…87 It is worth noting that EPD has also been successfully used to deposit a layer of bioactive glass on the struts of mechanically strong but almost-inert ceramic scaffolds. 88 In this way, multifunctional properties can be imparted to the porous substrate, namely apatite-forming ability 89 and controlled release of therapeutic agents (eg, strontium ions that can reduce bone resorption in osteoporotic patients). 90 Bioactive glass coatings on porous silicate glass-ceramics were also produced by simple dipping in a sol or glass slurry, but this approach provided less control on the coating characteristics (eg, thickness, homogeneity, reproducibility) compared to EPD.…”

Bioactive glass and glass‐ceramic orbital implants

“…[47][48][49][50][51] These strategies were also pursued in the field of orbital implants, as described in the next sections. [47][48][49][50][51] These strategies were also pursued in the field of orbital implants, as described in the next sections.…”

“…Looking at the existing literature, bioactive glasses have been mainly (a) used to fabricate porous or monolithic glassceramic products, or (b) embedded as bioactive inclusions within a porous polymeric matrix to create a composite, or else (c) applied as a coating on a non-resorbable porous framework. [47][48][49][50][51] These strategies were also pursued in the field of orbital implants, as described in the next sections. Specifically, the approaches (b) and (c) are motivated by the need for retaining a permanent skeleton that supports the periocular tissues over the patient's lifetime as the bioactive glass slowly dissolves.…”

Atmospheric Plasma Spray Processes: From Micro to Nanostructures

“…Biomaterials can be obtained with different techniques, thermal spraying shows significant advantages; in particular, the fact that the deposition and consolidation of the coating occur simultaneously without the need of a sintering treatment. Bioactive glasses are considered promising materials to be used as coatings onto implant devices, due to their high bioactivity [36,37]. The use of solutions precursor instead of traditional thermal spraying feedstock provides unique properties, i.e., high purity materials (avoiding possible contamination from feedstock preparation steps), and nanostructured coatings with denser and more homogeneous microstructures [38].…”