# Nanogravimetric and Optical Characterizations of Thrombin Interaction with a Self-Assembled Thiolated Aptamer

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- Authors: Jane Politi, Ilaria Rea, Fabrizia Nici, Principia Dardano, Monica Terracciano, Giorgia Oliviero, Nicola Borbone, Gennaro Piccialli, Luca De Stefano
- Journal: Journal of Sensors
- Year: 2016
- Volume: 2016
- Pages: 1–8
- DOI: 10.1155/2016/3561863
- Instrument used: openQCM 1

## Abstract

Efficient biorecognition of thrombin (TB), a serine protease with crucial role in physiological and pathological blood coagulation, is a hot topic in medical diagnostics. In this work, we investigate the ability of synthetic thrombin aptamer (TBA), immobilized on a gold substrate, to bind thrombin by two different label-free techniques: the quartz crystal microbalance (QCM) and the spectroscopic ellipsometry (SE). By QCM characterization in the range from 20 to 110 nM, we demonstrate high specificity of TBA-TB interaction and determine affinity constant ($K_d$) of 17.7 ± 0.3 nM, system sensitivity of 0.42 ± 0.03 Hz nM$^{-1}$, and limit of detection (LOD) of 240 ± 20 pM. The interaction between TBA and TB is also investigated by SE, an all-optical method, by quantifying the thickness increase of the TBA film assembled on gold substrate. AFM characterization of TBA and TB molecules deposited on flat silicon surface is also supplied.

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