Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationspresence of a small amount of carboxyl (O=C-O) carbon on the ALAPP film, whichwould contribute to the anionic properties of the film, is suggested by the presence ofa C 1s component at 289.1 eV (Figure 2.4A, Table 2.2).-potential measurements of bare silicon, ALAPP and PEG films over a pH rangefrom 4-7.5 are shown in Figure 3.1. Initially, the -potential of bare silicon wasmeasured. This surface had a negative charge (≈-15 mV), likely due to the silicategroups on the silicon surface, which did not significantly alter over the pH rangemeasured. Initially, when the -potential was measured for ALAPP coatings aftershort storage (2 days), a dynamic surface charge was observed, and an isoelectricpoint of approximately 5.5 was determined. This compares closely to work by Muiret al. [193], who reported an isoelectric point of 5.2 for an ALAPP film prepared andtreated under similar conditions. Typically, aliphatic primary amines tend to have apKa of 9-11, thus this low pI suggests the presence of additional anionicfunctionalities such as carboxylic acids.3-109