Gradation of proteins and cells attached to the surface of bio-inert zwitterionic polymer brush

Abstract

A self-assembled monolayer (SAM) of a 2-bromoisobutyryl end group-carrying initiator for atom transfer radical polymerization (ATRP) was constructed on the surface of silicon wafer or glass substrates via a silane-coupling reaction. When the initiator SAM was irradiated with UV light at 254nm, the surface density of bromine atoms was reduced by the scission of CBr bonds as observed by XPS. With the surface-initiated ATRP of the zwitterionic vinyl monomer, carboxymethyl betaine (CMB), the surface density of PCMB brushes could be easily varied by changing the irradiation period of UV light prior to the polymerization. Furthermore, by using a UV-cut shutter sliding above the initiator SAM-modified substrate at a constant speed, the degree of bromine atom removal could be linearly varied along the direction of movement of the shutter. Consequently, the amount of both proteins adsorbed and cells adhered to the PCMB brush-covered substrate could easily be controlled by the gradation of the surface density of PCMB brushes, which suppressed protein adsorption and cell adhesion. Such a technique is very simple and useful for the regulation of the surface density of adsorbed proteins and adhered cells on an originally bio-inert surface.

Effective Synthesis of Patterned Polymer Brushes with Tailored Multiple Graft Densities

“…Because of the different properties (e.g., different biocompatibility, molecular recognition, and electron conductivity) arranged on a single surface, the patterned polymer brushes allow applications in, e.g., bio-microarray detection, molecular recognition analytical devices, and microelectronic devices. , Surface-initiated living radical polymerization has been used to prepare such patterned polymer brushes from prepatterned initiators. ,,,− Several advanced techniques, such as electron-beam lithography, , interference laser lithography, , scanning-probe lithography, − and microcontact printing, , have successfully been used to prepare the prepatterned initiators with controlled surface densities. Not only the high-energy beam and laser but also low-energy UV light (≤254 nm), plasma, and UV/ozone were exploited to degrade alkyl bromide surface-initiators of atom transfer radical polymerization (ATRP). − However, the UV degradation of the alkyl bromides is time-consuming (≥3.5 h), limiting its extensive use.…”

Biomimetic Principles to Develop Blood Compatible Surfaces

“…Early studies on material surface modifications were performed with single zwitterions, but macromolecular approaches have gained increasing importance mainly because polyzwitterions provide a more robust coating and are more efficient at blocking original surface ions (44, 45). This finding has received strong support by adsorption experiments of fibrinogen and cells such as fibroblasts or platelets on surfaces with different coverage of pSBE or pCB brushes, where the capability to prevent fouling correlated with the degree of grafting (46–48). Furthermore, the surface roughness can be effectively smoothed by brush grafting with additional positive effects on material biocompatibility (49).…”

UV‐Patterning of Anti‐Biofouling Zwitterionic Copolymer Layer with an Aromatic Anchor Group

“…The nonspecific adsorption of BSA on the copolymer layer on the glass substrate and the silicon wafer was evaluated using the bicinchoninic acid (BCA) method reported elsewhere …”

“…However, the existing surface modification methods cannot contribute effectively to the development of novel biological materials, and the materials and methods for achieving surface modification, which provide excellent functionalities and abilities to the modified materials, should be intensively investigated . Moreover, optical microfabrication techniques involving irradiation with UV light and ion beams have been combined with surface modification techniques using polymers to obtain functional surfaces.…”