Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationsof polymer arrays. PEI arrays were scanned using a GenePix 4000A microarrayscanner. PEI spots were analysed using ImageQuant V 5.2 software.Poly(acrylic acid) (PAA) (Aldrich, MW 90,000), PEI, poly(L-lysine) (PLL)(Sigma, MW 70,000) and poly(vinyl pyrrolidone) (PVP) (Fluka, MW 380,000) werespotted onto ALAPP-PEG coated glass. Before spotting, polymer samples wereprepared to 4.0 mg/ml solutions in ultra pure water containing 2.0 mg/ml (6.6 mM),1.00 mg/ml (3.3 mM), 0.50 mg/ml (1.6 mM) or 0.00 mg/ml (0.0 mM) N-succinimidyl-5-azido-2-nitrobenzoate (NSANB) (Fluka) and polymer-NSANBsolutions were incubated at 25 °C for 10 min before array formation. Alternatively,PAA (8.0 mg/ml) was prepared in 50 µl of ultra pure water containing 150 mM N-hydroxy succinimide (NHS) (Sigma) and 60 mM 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (Fluka) and incubated for 1 hr at 37 °C. 50 µl of4.0 mg/mL (13.2 mM), 2.0 mg/mL (6.6 mM), 1.0 mg (3.3 mM) or 0.0 mg (0.0 mM)NSANB in ultra pure water containing 14.0 mM ethylenediamine (Merck) at 25 °Cwas incubated for 10 min before adding to the 50 l of activated PAA, to make afinal volume of 100 l, and incubating for a further 10 min before array formation.For analysis by profilometry, arrays were prepared from initial polymerconcentrations of 2.00, 1.00, 0.50, 0.25, 0.10 or 0.00 mg/ml containing 1.0 mg/ml(3.3 mM) NSANB solution. Spotting was conducted using a BioOdysseyCalligrapher MiniArrayer (Bio-Rad) using a 375 µm diameter solid pin (ArrayIt) at ahumidity of 65% and a temperature of 25 °C. The approach speed of the pin and thedwell time of the pin in contact with the surface were set to 20 mm/s and 15 msrespectively. All polymer spotting and solution preparation was conducted in thedark. All solutions used for spotting were made to a final volume of 50 µl. Afterarray formation samples were exposed to UV (25 W) for at least 10 mins, which was4-135