Plasma surface functionalization: A comprehensive review of advances in the quest for bioinstructive materials and interfaces

Abstract

Surface biofunctionalization aims to create cell-instructive surfaces that control the behavior of cells and modulate cellular interactions by incorporating cell signaling moieties at the materials–biosystem interface. Despite advances in developing bioinert and biocompatible materials, blood clotting, inflammation, and cell death continue to be observed upon the contact of foreign materials with living tissues leading to the materials' rejection. Specific examples include the application of foreign materials in implantable devices (e.g., bone implants, antimicrobial surfaces, and cardiovascular stents), biosensors, drug delivery, and 3D-bioprinting. Biofunctionalization of materials to date has been predominantly realized using wet chemical approaches. However, the complexity of wet chemistry, toxicity of reactants, waste disposal issues, reaction time, poor reproducibility, and scalability drive a need for a paradigm shift from wet chemical approaches to dry methods of surface biofunctionalization. Plasma-based technologies that enable covalent surface immobilization of biomolecules have emerged as dry, reagent-free, and single-step alternatives for surface biofunctionalization. This review commences by highlighting the need for bioinstructive surfaces and coatings for various biomedical applications such as bone implants, antimicrobial surfaces, biosensors, and 3D-bioprinted structures, followed by a brief review of wet chemical approaches for developing biofunctionalized surfaces and biomimetic devices. We then provide a comprehensive review of the development of plasma-based technologies for biofunctionalization, highlighting the plasma–surface interactions and underpinning mechanisms of biomolecule immobilization.

Durable plasma-mediated zwitterionic grafting on polymeric surfaces for implantable medical devices

“…This process was fundamentally facilitated by the ability of PIII technologies to generate radical-functionalized substrates that allow the immobilisation of zwitterionic moieties at the surface. During PIII treatment, energetic bombardment by nitrogen ions generates long-lived reactive radicals that migrate to the surface over time through thermally activated processes 39,52,53 . Upon immersion in zwitterion solution, such surface-embedded radicals facilitate covalent interactions between the SBMA moieties and the PU surface, resulting in ZG-PU.…”

“…4c-ii), which can be attributed to the absence of a reservoir of embedded radicals. Without ion bombardment, air plasma treatment provides a shallow treatment depth (i.e., a few nanometres), whereas PIII can embed radicals in depth up to 100 nm under the surface 39 . After their initial rapid shifts, the longer-term hydrophobic recovery trends in both groups were the same (Fig.…”

“…Alternatively, linker-free approaches may facilitate improved scalability, efficiency, and versatility. One outstanding linker-free strategy involves the functionalization of a polymer substrate with plasma (i.e., ionised gas), providing surface-anchored reactive sites that can participate in zwitterion grafting 39 . Recently, plasma functionalisation has been used to graft zwitterions onto poly(vinylidene fluoride) 40,41 and poly(ethylene) [42][43][44] surfaces, with these studies collectively demonstrating low fouling against a range of proteins (such as fibrinogen 40 , bovine serum albumin 41,42 , and lysozyme 41 ), resistance to platelet adhesion and activation 40 , and low microbial adhesion and biofilm formation 41,43,44 .…”

“…Recently, plasma functionalisation has been used to graft zwitterions onto poly(vinylidene fluoride) 40,41 and poly(ethylene) [42][43][44] surfaces, with these studies collectively demonstrating low fouling against a range of proteins (such as fibrinogen 40 , bovine serum albumin 41,42 , and lysozyme 41 ), resistance to platelet adhesion and activation 40 , and low microbial adhesion and biofilm formation 41,43,44 . A particularly robust plasma functionalization platform is plasma immersion ion implantation (PIII), which involves the bombardment of ions into the material surface to generate a reservoir of surface-embedded radicals, which can then be used to anchor desired moieties in a linker-free manner 39,45 .…”

The applications of cold atmospheric plasma in dentistry

“…The name CAP (cold atmospheric pressure plasma) is another name for this particular kind of plasma. [3,[28][29][30]…”