A boronate affinity restricted-access material with external hydrophilic bottlebrush polymers for pretreatment of cis-diols in biological matrices

Abstract

Restricted-access materials (RAMs) have found their broad application in sample pretreatment of bioanalysis. Boronate affinity (BA) adsorption is a very efficient and facile method for isolation and enrichment of cis-diol containing biomolecules which are a large important group compounds in biosystems. However, preparation of BA-RAMs are rarely reported to date. In this study, a novel BA-RAM with external surface comprised of hydrophilic bottlebrush polymers was prepared exploiting the excellent capability of the bottlebrush polymers for protein exclusion. A diblock copolymer poly(3-acrylamidophenylboronic acid)-block-poly(2-hydroxyethyl methacrylate) (PAAPBA-b-PHEMA) was first grafted from the silica surface via surface-initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT), and poly(N-isopropylacrylamide) (PNIPAAm) was then grafted from the PHEMA via surface-initiated atom transfer radical polymerization (SI-ATRP) to yield the BA-RAM. The BA-RAM exhibits high selectivity to cis-diol containing small molecules and has good capability to exclude proteins. Its practical application in bioanalysis was tested by pretreatment of serum sample for analysis of catecholamines with high recoveries and good precision. The preparation strategy for the BA-RAM is very versatile and is easy to be expanded to other modes of RAMs.