Protein-surface interactions PNIPAAm

From another point of view, atomic force microscopy is focused on the intermolec-ular interactions between proteins (coated on the atomic force microscopy probe) and PNIPAAm surfaces at different temperatures. Using this method, Cho et al. reported several studies on intermolecular force between BSA and PNIPAAm surfaces (Cho, Kim, Cho, 2004 Cho, Kim, Cho, 2005 Cho, Kim, Cho, 2008). They observed a temperature-dependent adhesion force (defined as the maximum attractive force during retraction of the surface from the tip), which is negligible at lower temperatures and suddenly increases to a maximum value as the temperature increases above a transition temperature (27-29 °C). The lower transition temperature compared with the LCST of PNIPAAm in water (32 °C) may be due to the addition of salts becanse the experiments were conducted in a phosphate bnffer solution. The change in adhesion force is consistent with the affinity between soluble proteins and a PNIPAAm surface, which, at room temperature, is approximately an order of magnitude lower than at 37 °C (Cheng et al., 2006). 

Capila I, Linhardt RJ (2002) Heparin-protein interactions. Angew Chem Int Ed 41 391 12 Carmeliet P (2003) Angiogenesis in health and disease. Nat Med 9 653-660 Chen CP, Imanishi Y, Ito Y (1998) Effect of protein and cell behavior on pattern-grafted thermoresponsive polymer. J Biomed Mater Res 42 38-44 Cheng XH, Canavan HE, Stein MJ et al (2005) Surface chemical and mechanical properties of plasma-polymerized N-isopropylacrylamide. Langmuir 21 7833-7841 Curti PS, de Moura MR, Veiga W et al (2005) Characterization of PNIPAAm photografted on PET and PS surfaces. Appl Surf Sci 245 223-233... 

Beyond the elastic modulus, SFM-based colloidal probe measuronents were successfully applied to study interaction forces between thermo-responsive polymers and protein-coated surfaces. This was shown by Cole, Voelcker, Thissen, Horn, and Griesser (2010) with bovine serum albumin-coated probes on PNiPAAm surfaces. Furthermore, time-dependent colloidal probe measuronents on thermo-responsive polymer coatings... 

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