POROUS SILICON NANOPARTICLES FOR THE INVESTIGATION OF TETHERED RECEPTOR-TARGET INTERACTIONS WITH MICROSCALE THERMOPHORESIS (MST)

Microscale thermophoresis (MST) allows for quantitative analysis of a broad range of receptor-target interactions (e.g. antibodies, aptamers, etc.^1,2,3) in free solution and with low sample consumption. Nevertheless, conventional MST requires labeling of one of the binding partners, which may alter the binding behavior.

Here, we introduce a novel label-free MST assay, based on photoluminescent porous silicon (PSi) nanoparticles (NPs), for rapid and high-throughput characterization of tethered aptamer-target interactions. The synthesized porous NPs (~250 nm in diameter with an average pore size of 50 nm) exhibit strong photoluminescence under UV excitement. Importantly, these NPs are well dispersed in aqueous solutions, allowing loading into MST capillaries. Measurements of their red fluorescence under excitation with blue light in the MST show consistent intensities which allow their use as labels. The NPs are accessible to a wide range of surface modifications enabling convenient immobilization of aptamers or other receptors onto their surface and within the pores. The functionalized PSi NPs can be titrated against the corresponding analyte to rapidly obtain the dissociation constant for the conjugated receptor. Specifically, we demonstrate the applicability of this generic assay for the characterization of the PSi-tethered aptamer-target dissociation constants, allowing for rapid optimization of aptamer sequences, surface density and conjugation chemistry.

1 Liu, Y. N., N. Liu, X. H. Ma, X. L. Li, J. Ma, Y. Li, Z. J. Zhou and Z. X. Gao (2015). Analyst 140(8): 2762-2770.

2 Nemie-Feyissa, D., B. Heidari, M. Blaise and C. Lillo (2015). Phytochemistry 111(0): 21-26.

3 Stambuk, N., Z. Manojlovic, P. Turcic, R. Martinic, P. Konjevoda, T. Weitner, P. Wardega and M. Gabricevic (2014). Int J Mol Sci 15(6): 9209-9223.