Protein Nanopatterning on Self-Organized Poly(styrene-b-isoprene) Thin Film Templates

Department of Physics and Surrey Materials Institute, University of Surrey, Guildford, Surrey, United Kingdom GU2 7XH.
Langmuir (Impact Factor: 4.46). 04/2009; 25(8):4526-34. DOI: 10.1021/la8038957
Source: PubMed


Templated surfaces can be used to create patterns of proteins for applications in cell biology, biosensors, and tissue engineering. A diblock copolymer template, which contains a pair of hydrophobic blocks, has been developed. The template is created from well-ordered, nonequilibrium surface structures of poly(styrene-b-isoprene) (PS-b-PI) diblock copolymers, which are achieved in ultrathin films having a thickness of less than one domain period. Adsorption and nanopatterning of bovine serum albumin (BSA) on these thin films were studied. After incubation of the copolymer templates in BSA solutions (500 microg/mL) for a period of 1 h, BSA molecules formed either a striped or a dense, ringlike structure, closely resembling the underlying polymer templates. In this "hard-soft" PS-b-PI system, BSA molecules were preferentially adsorbed on the hard PS domains, rather than on the soft PI domains. Secondary ion mass spectroscopy (SIMS) and contact angle analysis revealed that, with more PI localized at the free surface, fewer BSA molecules were adsorbed. SIMS analysis confirmed that BSA molecules were adsorbed selectively on the PS blocks. This is the first example of two hydrophobic blocks of a diblock copolymer being used as a protein patterning template. Previously reported diblock copolymer templates used hydrophilic and hydrophobic pairs. A potentially useful characteristic of this template is that it is effective at high protein solution concentrations (up to 1 mg/mL) and for long incubation times (up to 2 h), which broadens its range of applicability in various uses.

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    • "Thin film stability is, in general, a crucial issue both from the fundamental point-of-view of phase stability in confined systems and from the viewpoint of applications. For example, in our own previous research, we found that the adsorption of the protein bovine serum albumin is very low on surfaces of polyisoprene (PI) [5], allowing the creation of protein nanopatterns on the surface of a microphase-separated copolymer containing PI as one block. Furthermore, the patterning of adhesion proteins on PI-copolymer surfaces has been shown to influence biological cell attachment and spreading [6]. "
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    • "This is commonly observed in systems where polystyrene is the hydrophobic component (Kumar and Hahm, 2005; Koutsopoulos et al., 2007; Lau et al., 2008; Liu et al., 2009). Bovine serum albumin (BSA) is a model protein commonly used in adsorption studies on both homopolymer and block copolymer surfaces (Lai et al., 2008; Lau et al., 2008; Liu et al., 2009). "
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