Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationsdue to post-deposition alterations. Thermodynamic studies were conducted with twodifferent batches of Si-ALAPP samples.Quartz crystal microbalance (QCM) measurements were taken using anElectrochemical Nanobalance EQCN-701 (Elchema). 9 V Quartz crystals(International Crystal Manufacturing Company) with gold electrodes were used forall measurements. The frequency of the crystal was measured and processed usingVoltscan and Master Windows software. Frequency changes were converted to masschanges using the Sauerbrey equation, shown as equation 3.2, where f is the changein frequency, m is the change in mass, a is a constant related to the crystal used andA is the area.m f a(3.2)AAll measurements were conducted in a Faraday cage under N 2 at roomtemperature. For DNA adsorption studies, one side of the quartz crystal was coatedwith an ALAPP film according to the procedure described previously. The coatedside was incubated in a 0.01 M phosphate buffer, pH 7.4, 0.5 M NaCl whilst theuncoated side was exposed to N 2 throughout. After 24 hr incubation, to allow forswelling of the polymer film and any post-deposition rearrangements and afterensuring the crystal had stabilised, a 300 g/ml plasmid solution was added to makea final DNA concentration of 200 ng/ml and the change in mass was measured.3.2.5. Data analysisThe adsorption of plasmid DNA to ALAPP and PEG films was modelled usingthe Langmuir model. The change in surface concentration of a species was related tothe bulk concentration by equation 3.3, where s corresponds to the surface3-105