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Issue 35, 2013
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Nanolayered chemical modification of silicon surfaces with ionizable surface groups for pH-triggered proteinadsorption and release: application to microneedles

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Abstract

The aim of this work was to develop a nanolayered pH sensitive coating method whereby proteins are coated at a suitable pH on the surface of chemically modified biomedical/bioanalytical microdevices and protein release is triggered by a pH-shift upon contact with the physiological environment. In this work such a coating was developed and was applied onto microneedles. First, the surface of microneedle arrays was modified with basic groups with a surface pKa below physiological pH. This modification was a multistep procedure: first the surface was hydroxylated in a piranha mixture, then 3-aminopropyl-triethoxysilane was coupled (yielding a “pH independent” surface with a positive charge over a broad pH range), next 4-pyridinecarboxaldehyde was coupled to the obtained surface amine groups and finally the imine bond was reduced by sodium cyanoborohydride. The obtained pH-sensitive pyridine-modified microneedles were coated with ovalbumin at surface pKa > pH > pI of the protein; thus the surface of the microneedles is positively charged and the protein is negatively charged. The coating efficiency of ovalbumin was 95% for the amine-modified (pH independent) and the pyridine-modified (pH sensitive) surfaces, whereas a non-modified surface had a coating efficiency of only 2%. After the protein-coated microneedle arrays were pierced into the skin, having a pH > surface pKa of the microneedle arrays, 70% of the protein was released within 1 minute, whereas the protein release from pH independent microneedle arrays was only 5%. In conclusion, we developed a procedure to efficiently coat microneedle arrays with proteins that are released upon piercing into human skin.

Graphical abstract: Nanolayered chemical modification of silicon surfaces with ionizable surface groups for pH-triggered protein adsorption and release: application to microneedles

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Publication details

The article was received on 03 Jun 2013, accepted on 09 Jul 2013 and first published on 09 Jul 2013


Article type: Paper
DOI: 10.1039/C3TB20786B
J. Mater. Chem. B, 2013,1, 4466-4477

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    Nanolayered chemical modification of silicon surfaces with ionizable surface groups for pH-triggered protein adsorption and release: application to microneedles

    K. van der Maaden, H. Yu, K. Sliedregt, R. Zwier, R. Leboux, M. Oguri, A. Kros, W. Jiskoot and J. A. Bouwstra, J. Mater. Chem. B, 2013, 1, 4466
    DOI: 10.1039/C3TB20786B

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