Functionalizable and ultra-low fouling zwitterionic surfaces via adhesive mussel mimetic linkages

In this work, a biomimetic polymer (pCB₂-catechol₂), with two zwitterionic poly(carboxybetaine) (pCB) arms for ultra-low fouling and two adhesive catechol groups for surface anchoring, was developed. Two pCB arms were grown from an initiator with two catechol groups via atom transfer radical polymerization (ATRP). Binding tests of pCB₂-catechol₂ were performed on a gold surface under a range of conditions such as pH values and solvents. Protein adsorption from single protein solutions of fibrinogen and lysozyme, and complex media of 100% blood plasma and serum was evaluated using a surface plasmon resonance (SPR) sensor. Results are compared with those from two other polymers (i.e., one polymer with one pCB chain and one catechol group, termed as pCB-catechol, and another polymer with one pCB chain and two catechol groups, termed as pCB-catechol₂). Furthermore, the direct immobilization of anti-activated leukocyte cell adhesion molecule (anti-ALCAM) was carried out on the pCB₂-catechol₂ modified surface. Results showed that the antibody-immobilized surface maintained its excellent ultra-low fouling properties. The detection of activated leukocyte cell adhesion molecule (ALCAM) in 100% blood plasma with high sensitivity and specificity was achieved. This work demonstrates an effective and convenient strategy to obtain functionalizable and ultra-low fouling surfaces.