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Patterned and switchable surfaces for biomaterial applications

Patterned and switchable surfaces for biomaterial applications

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Andrew Hook – <strong>Patterned</strong> <strong>and</strong> <strong>switchable</strong> <strong>surfaces</strong> <strong>for</strong> <strong>biomaterial</strong> <strong>applications</strong>3.3.4. Electro-stimulated DNA adsorption <strong>and</strong> desorptionAs a final study, the electro-stimulated adsorption <strong>and</strong> desorption of DNA to boththe ALAPP <strong>and</strong> PEG films was studied using measurements of the depletion ofsolution fluorescence. Initially the films were incubated in DNA solution overnight.Subsequently, +1.50 V was applied <strong>for</strong> 2 min to promote further DNA adsorption.After stabilisation <strong>for</strong> 4 mins, whereupon no voltage was applied, the polarity of thevoltage was reversed <strong>and</strong> -0.75 V was applied <strong>for</strong> 2 min in order to trigger DNAdesorption. After each voltage application, the DNA concentration of the bulksolution was determined by fluorescence spectroscopy <strong>and</strong> related to changes in the DNA . Delamination of the ALAPP or ALAPP-PEG films was not observed aftervoltage application.The results are shown as Figure 3.9. Notably, very low DNA (

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