Generic Top-Functionalization of Patterned Antifouling Zwitterionic Polymers on Indium Tin Oxide

Abstract

This paper presents a novel surface engineering approach that combines photochemical grafting and surface-initiated atom transfer radical polymerization (SI-ATRP) to attach zwitterionic polymer brushes onto indium tin oxide (ITO) substrates. The photochemically grafted hydroxyl-terminated organic layer serves as an excellent platform for initiator attachment, and the zwitterionic polymer generated via subsequent SI-ATRP exhibits very good antifouling properties. Patterned polymer coatings can be obtained when the surface with covalently attached initiator was subjected to photomasked UV-irradiation, in which the C-Br bond that is present in the initiator was broken upon exposure to UV light. A further, highly versatile top-functionalization of the zwitterionic polymer brush was achieved by a strain-promoted alkyne-azide cycloaddition, without compromising its antifouling property. The attached bioligand (here: biotin) enables the specific immobilization of target proteins in a spatially confined fashion, pointing to future applications of this approach in the design of micropatterned sensing platforms on ITO substrates.

Structures and Synthesis of Zwitterionic Polymers

“…Nevertheless, the iniferter [304][305][306], RAFT [307][308][309][310][311] and NMP [130,312] methods have been demonstrated to work well, too. Importantly, the RDRP methods do not only allow to tailor anti-fouling zwitterionic polymer films, they also allow to functionalize them conveniently with reactive groups [268,270]. This is most valuable for anchoring additional functionalities to the tethered polymers, for instance, for incorporating specific recognition units for biomolecules.…”

Zwitteration: Coating Surfaces with Zwitterionic Functionality to Reduce Nonspecific Adsorption

“…63 Bacterial adhesion was also inhibited. 64 Since about 2009 the number of works employing graft polymerization of polyzwitterions from/to surfaces has increased dramatically, as witnessed by grafting from silicon nitride, 49,65 polypropylene membranes, 66 various surfaces using a bioinspired peptide initiator, 67 indium tin oxide conducting glass, 48 gold, 68 hydrogels, 69 filtration membranes, 70 conducting polymers, 71 cellulose membranes, 72 and polysulfone membranes. 73 …”

Antifouling Stripes Prepared from Clickable Zwitterionic Copolymers

“…1–6 Cell micropatterning can be achieved with fouling resistant materials that enable selective cell adhesion while limiting the non-specific adsorption of biomolecules. 7–15 Currently, poly(ethylene glycol) (PEG) is the most widely-used antifouling polymer for grafting and lithographical patterning. 10–14 However, the polyether structure and terminal hydroxyl groups of PEG leads to oxidative degradation in the presence of oxygen.…”