Physico-Chemical nanomaterials science

New AuNPs-Si@C probes for analysis applications
Lisnyak V. V. 1,2, Mussabek G. K.2,3, Zhylkybayeva N. Zh.2,3, 
Baktygerey S. Z.2,3, Lavs’ka V.O.1, Zaderko A. N.1
1 Taras Shevchenko National University of Kyiv, Volodymyrska Street, 64/13, Kyiv 01601, Ukraine. E-mail: lisnyak@univ.kiev.ua
2 Institute of Information and Computational Technologies, 125, Pushkin Str., 050000 Almaty, Kazakhstan
3 Al-Farabi Kazakh National University, 71, Al-Farabi Ave., 050040 Almaty, Kazakhstan

Silicon nanoparticles (Si NPs) are promising candidates for a diverse range of applications, in part because of their tunable photoluminescence, bio-compatibility, and low toxicity. We can adapt them to changes in the surroundings and are the objects of increased scientific interest to new probes. 
In this communication, we report that Si NPs with a hydride surface can be functionalized with carbon and carbon-oxygen-containing groups forming Si@C probes. The reaction was performed under solvothermal conditions with short reaction times. The functionalized Si@C probes can form colloidal stable dispersions. The proposed functionalization proceeds through forming Si–C bonds and also leads to the surface Si–C–O species. We showed that sensing biologically relevant molecules such as glucose, dopamine, ethanol, and some antibiotics is workable with the prepared probes. When modified with Au NPs, they showed surface-enhanced Raman scattering (SERS) sensors for rapid and accurate on-site detection of target analytes. Herein, we present the first demonstration of a portable carbon-covered silicon-based SERS analytical platform for signal-on detection of trace glucose, dopamine, ethanol, and some nitro compounds, which is made of gold nanoparticles (AuNPs)-decorated Si@C probe. Under 514 nm excitation, the Raman signals of analyte adsorbed on the AuNP surface are dependent on the formation of electronic resonance-active complexes. In addition, the surface of AuNPs-Si@C probes via substrate-induced plasmon resonances also contributes to the total SERS enhancement. In sum, about 10–6 M of the targeted analytes can be detected using such a portable device, showing its feasibility in analytical determination.
ACKNOWLEDGEMENTS
G.K. Mussabek, S.Z. Baktygerey, and V.V. Lisnyak acknowledge the support of Grant No AP08856579 of the Ministry of Education and Science of the Republic of Kazakhstan.