Design And Development Of Biomimetic Adhesive Zwitterionic Polymers For The Preparation Of Ultralow-fouling Surfaces

A great challenge in many applications, ranging from biomedical devices to ship hulls, is the prevention of nonspecific biomolecular and microorganism attachment on surfaces. For example, nonspecific protein adsorption degrades the performance of surface-based diagnostic devices and causes an adverse effect on the healing process for implanted biomaterials. Herein ultralow-fouling zwitterionic surfaces were prepared via adhesive mussel mimetic linkages. Protein adsorption was measured using a surface plasmon resonance (SPR) sensor, and the accumulation of Pseudomonas aeruginosa on the surfaces was studied in situ using a laminar flow chamber.Nonfouling sulfobetaine polymers were first grafted via surface-initiated atom transfer radical polymerization (ATRP) from surfaces covered with an adhesive catechol initiator. The nonfouling performances of the resulting polymer brushes on gold and NH2-gold surfaces were compared. Under optimal conditions, ultralow protein adsorption from both single protein solutions and blood plasma/serum was achieved. Furthermore, the 9-day accumulation of Pseudomonas aeruginosa on the treated glass surfaces was studied. The results showed that these sulfobetaine coatings dramatically reduced the biofilm formation of P. aeruginosa as compared to the reference bare glass.Biomimetic polymers with a poly(sulfobetaine) (pSB) moiety for ultralow fouling and a catechol end group for surface anchoring have been developed. Binding tests of the adhesive polymer on various surfaces, including amino (NH2), hydroxyl (OH), and methyl (CH3) terminated self-assembled monolayers (SAMs) along with bare gold, were performed under acidic and basic conditions. Under optimized conditions, the coated surfaces are highly resistant to non-specific protein adsorption from both single protein solutions and blood serum/plasma. Furthermore, the 3-day accumulation of Pseudomonas aeruginosa on the coated surfaces was evaluated. Results show that the coated surfaces are highly resistant to biofilm formation. This work demonstrates a convenient and efficient method for using zwitterionic polymers to achieve ultralow fouling surfaces via surface modification, for applications in complex media.Furthermore, two kinds of nonfouling polyampholytes with biomimetic adhesive groups were synthesized by the polymerization of a cationic-anionic comonomer using two types of catecholic initiators. One polyampholyte with two catechol anchoring groups and two nonfouling zwitterionic arms was obtained by ATRP, and the other one was got by free radical polymerization. Results showed that the surfaces modified with both of these polymers had excellent nonfouling properties.Finally, a biomimetic polymer (pCB2-catechol2), with two zwitterionic poly(carboxybetaine) (pCB) arms for ultralow fouling and two adhesive catechol groups for surface anchoring, was developed. Binding tests of pCB2-catechol2 were performed on a gold surface under a range of conditions (various pH values and solvents). Protein adsorption from single protein solutions blood plasma/serum was evaluated. Results were compared with those from two other polymers (i.e., pCB-catechol and 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 ultralow 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 ultralow fouling surfaces.