Surface Functionalization of Nanowires Using Silane-PEG Compounds

Sammanfattning: Introduction: GaP nanowires were functionalized using silane-PEG-NH2 and compared with cellulose acetate, PAcrAm™-g-(PMOXA, amine, silane) and a non-functionalized reference sample. Functionalization would allow strong, covalent anchoring of antibodies instead of adsorption. Aim: The thesis work focused on deciding on, and optimizing, a protocol for nanowire surface modification of the three mentioned functional compounds. Methods: The different surface treatments were qualitatively compared using optical microscopy. The fluorescence of the different samples was analyzed using a full-factorial DOE of four concentrations of each functionalization incubated in four different concentrated antibody solutions. The functionalizations' success and the protocol alterations' impact were validated using SEM and TEM imaging. Results: The functionalized samples had considerable drying effects following the initial treatments, visible in the optical microscope and SEM. All protocols were altered to allow slow drying, by covering the Petri dishes with a lid, resulting in significantly decreased drying effects. The detected fluorescent signal was higher for the silanized samples compared to the other functionalities and the reference. However, all functionalized samples without antibodies did reveal an exceedingly high signal, indicating cross-contamination. Further TEM examination of the different samples revealed that none of the functionalized nanowires had any additional compound on their surfaces. This indicates unsuccessful surface treatments for all functional compounds or functionalization of a small fraction of the sample, thus requiring a more extensive TEM analysis. Conclusion: The surface treatment protocols were improved by implementing slow drying. However, a more extensive TEM examination is required to quantify the extent of the different surface modifications. Furthermore, repeats of the final protocol are required to validate the possible signal-enhancement observed for the silanized nanowires.