Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationsThe same study also demonstrated the electro-stimulated adsorption anddesorption of DNA from the ALAPP surface, whereupon the DNA surfaceconcentration ( DNA ) was increased from 0.4 mg/m 2 to 1.0 mg/m 2 by application of apositive voltage and decreased to 0.2 mg/m 2 after application of a negative voltage(see section 2.3.2) [34]. The ability to electro-stimulate the adsorption and desorptionof DNA has also been studied extensively on gold [18, 105-107].In the present chapter, the adsorption of DNA to ALAPP and PEG layers wasinvestigated to achieve an in-depth understanding of the biomolecule-surfaceinteractions using a range of surface analytical methods including X-rayphotoelectron spectroscopy (XPS), -potential, contact angle and quartz crystalmicrobalance (QCM) measurements. Furthermore, studies into the electro-stimulatedadsorption and desorption of DNA on these substrates were conducted.3.2. Materials and methods3.2.1. Substrate preparationsBoron doped p ++ silicon wafers (Virginia Semiconductors, Inc.) were cut intoapproximately 10 x 10 mm 2 pieces, cleaned by sonication for 30 min in a 5%surfactant (RBS 35, Pierce USA) solution and oxidised under UV light for 30 min.Plasma polymerisation reactions onto prepared substrates were performed in acustom-built reactor described elsewhere [182]. In short, the plasma reactor consistedof two circular electrodes separated by 125 mm in a cylindrical reactor being 350mm high with a diameter of 170 mm. Allylamine (Aldrich, 98% purity) was used asa monomer. Polymerisation conditions used were a frequency of 200 kHz, a power of20 W and an initial monomer pressure of 0.200 mbar. Deposition time was 25 s3-101