DETECTION OF GOLD NANOPARTICLES BY ELECTROCHEMICALLY DEPOSITED SOL-GEL BASED NANOPARTICLES IMPRINTED MATRICES

Speciation of nanoparticles, that is, their differentiation based on size, shape and stabilizing shell, is becoming important because of properties such as toxicity that strongly depend on these parameters. Nanoparticle imprinted polymers (NAIMs) is a new approach derived from the molecularly imprinted polymer approach, in which nanoparticles are imprinted instead of molecules^1-3. NAIMs require the preparation of thin films onto which nanoparticles are deposited, followed by the triggered release of the nanoparticles template. The matrix imprinted with voids is subsequently used for selective reuptake of nanoparticles similar to those used in the imprinting procedure.

In this study, we explored the effect of different sol-gel matrices for embedding AuNPs stabilized with citrate (AuNP-cit). The AuNP-cit were first deposited onto an indium tin oxide (ITO) electrode, which was treated with positively charged polymer, which caused negatively charged AuNP-cit to be adsorbed onto the electrode surface. Then, different sol-gel matrices with different thickness and functional groups were electrodeposited onto the electrode. Electrochemical oxidation dissolved the AuNPs-cit and formed cavities in the sol-gel films, which fit both the size and shape of the AuNPs-cit. Reuptake of these nanoparticles from an aqueous solution was successful using the imprinted films, whereas the control non imprinted films did not reuptake the AuNPs-cit.

We found that the type of the silanes that were deposited and the thickness of the sol-gel layer have a crucial effect on the recognition ability. Furthermore, we showed that the NAIMs are selective and larger AuNPs-cit were not recognized by the imprinted matrix.

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