Recent Developments in the Design of Non-Biofouling Coatings for Nanoparticles and Surfaces.

Carlos Sanchez-Cano,Mónica Carril

doi:10.3390/ijms21031007

Abstract

Biofouling is a major issue in the field of nanomedicine and consists of the spontaneous and unwanted adsorption of biomolecules on engineered surfaces. In a biological context and referring to nanoparticles (NPs) acting as nanomedicines, the adsorption of biomolecules found in blood (mostly proteins) is known as protein corona. On the one hand, the protein corona, as it covers the NPs’ surface, can be considered the biological identity of engineered NPs, because the corona is what cells will “see” instead of the underlying NPs. As such, the protein corona will influence the fate, integrity, and performance of NPs in vivo. On the other hand, the physicochemical properties of the engineered NPs, such as their size, shape, charge, or hydrophobicity, will influence the identity of the proteins attracted to their surface. In this context, the design of coatings for NPs and surfaces that avoid biofouling is an active field of research. The gold standard in the field is the use of polyethylene glycol (PEG) molecules, although zwitterions have also proved to be efficient in preventing protein adhesion and fluorinated molecules are emerging as coatings with interesting properties. Hence, in this review, we will focus on recent examples of anti-biofouling coatings in three main areas, that is, PEGylated, zwitterionic, and fluorinated coatings.

Highlights

Biofouling is the spontaneous and unwanted adsorption of biomolecules, cells, or microorganisms on engineered surfaces [1]
The gold standard in the field is the use of polyethylene glycol (PEG) molecules, zwitterions have proved to be efficient in preventing protein adhesion and fluorinated molecules are emerging as coatings with interesting properties
In a biological context and referring to nanoparticles (NPs) acting as nanomedicines, the adsorption of biomolecules found in blood is known as protein corona [3] and is usually a consequence of the opsonization process that foreign species undergo in the body in order to be recognised as intruders by phagocytic cells (Figure 1)

Summary

Introduction

Biofouling is the spontaneous and unwanted adsorption of biomolecules, cells, or microorganisms on engineered surfaces [1]. It is a consequence of the surface properties, such as the charge, hydrophobicity, or coating grafting density, which are derived from either the bulk material or the surface’s coating In clinical practice, it has a major role in the design and development of surgical implants because biofouling can produce hemolysis, coagulation problems, immunogenicity, and thrombosis, and it is related to bacterial biofilm formation, leading to infections and implant rejections, among other problems [2]. Most anti-biofouling coatings seem to adhere to four general principles [21], which are as follows: (i) an overall neutral surface charge; (ii) the presence of hydrogen bond acceptors; (iii) the absence of hydrogen bond donors; and (iv) a high hydrophilicity to promote hydration The idea behind those principles is to avoid electrostatic or hydrophobic interactions with charged patches or hydrophobic pockets present in proteins and, on the contrary, favor the formation of a layer of water. Other coatings have been described, such as those based on phospholipids [26] or some saccharides [27,28], in this review, we will focus on recent examples of the design of anti-biofouling coatings in three main areas, that is, PEGylated, zwitterionic, and fluorinated coatings [1]

PEGylated Coatings

Zwitterions

Findings

Fluorinated Hydrophobic Coatings