Roles of polymer brushes in biological applications

Abstract

Polymer brushes are macromolecular structures with polymer chains tethered to a surface resembling a brush. They have shown variety of uses in biological applications. Because of the nature of crafted polymers, the functionalized surfaces exhibit unique functions such as low friction, altered adhesion, protein binding and selective adsorption. Functionalization can be controlled by changing parameters such as grafting densities, chemical configurations, shapes and thickness. In this review, a particular emphasis has been provided for studies related to biological applications of polymer brushes based on their ultra-low friction, hydrophilic elongated surfaces, and binding properties. It provides useful information for researches and labs working on finding better solutions for drug delivery, arthritis, artificial joints, antibiofouling coatings and protein immobilization and purification.

Supramolecular Polymer Brushes

“…1−5 Polymer brushes have attracted interest not only for a range of biological applications that include artificial joints, drug delivery, antibiofouling surfaces, and biosensors but also for membrane and nanomaterials engineering. 2,3,6 Two important molecular parameters that describe a polymer brush are the molecular weight of the polymer grafts (which is correlated with the dry film thickness) and the grafting density of the polymer brush. The grafting density σ is defined as the number of polymer chains per unit surface area, usually given as chains/nm 2 .…”

Brush-Modified Hydrogels: Preparations, Properties, and Applications

“…Hydrogels modified with surface polymer molecular brushes are mainly prepared by atom transfer radical polymerization (ATRP), ,,,, activators regenerated by electron transfer for ATRP (ARGET-ATRP), , or photoinduced electron/energy transfer-RAFT (PET-RAFT) polymerization . The surface modification strategies consist of “grafting onto” and “grafting from”.…”

“…“Grafting from” is achieved by physical or chemical adsorption from monomer polymerization grafting, which is a bottom-up grafting method commonly used for surface radical polymerization reactions (Figure ). ,, …”

“…Hydrogels are promising for a broad range of applications given their outstanding properties of swellability, toughness, flexibility, elasticity, viscoelasticity, fatigue resistance, diffusivity, antifouling, and biomimetic environment. − Hydrogel materials with different structures have been designed to implement variable functions, and they have been extensively employed in cell culture, , drug delivery, − tissue scaffolds, − wound dressings, − antifouling materials, − contact lenses, , sensors, flexible and wearable sensing electronics, − lubricating material, − anti-icing, − optical devices, , batteries, , and soft robotics. ,, The chemical composition and the spatial topology of hydrogels determine their properties and functions, which are pivotal for practical applications. The polymer chain of hydrogel with identical compositions can be accommodated in the local environment in various topologies, ranging from linear form to grafted, blocky, star-shaped, bottlebrush, and other complex architectures . Polymer brushes (bottlebrushes) are unique polymer structures with a high grafting density of pendant polymer chains that are anchored to a primary linear backbone (one-dimensional, 1D), the surface of a planar matrix (two-dimensional, 2D), or spherical or cylindrical matrices (three-dimensional, 3D). − It is generally recognized that the reduced tethered density can be used for the quantitative characterization of the transition between a single grafted chain (mushroom) regime and the brush regime.…”

“…The polymer chain of hydrogel with identical compositions can be accommodated in the local environment in various topologies, ranging from linear form to grafted, blocky, star-shaped, bottlebrush, and other complex architectures. 40 Polymer brushes (bottlebrushes) are unique polymer structures with a high grafting density of pendant polymer chains that are anchored to a primary linear backbone (one-dimensional, 1D), the surface of a planar matrix (two-dimensional, 2D), or spherical or cylindrical matrices (three-dimensional, 3D). 41−43 It is generally recognized that the reduced tethered density can be used for the quantitative characterization of the transition between a single grafted chain (mushroom) regime and the brush regime.…”