Supporting materials

Nanogravimetric and Optical Characterizations of Thrombin

Interaction with a Self-assembled Thiolated Aptamer

Jane Politi1,2, Ilaria Rea1, Fabrizia Nici3, Principia Dardano1, Monica Terracciano1,3, Giorgia

Oliviero3, Nicola Borbone3, Gennaro Piccialli3, Luca De Stefano1*

1 Institute for Microelectronics and Microsystems, National Research Council, Unit of Naples, Via

P. Castellino, 111, 80131, Naples, Italy

2 Department of Chemistry, University of Naples “Federico II”, Via Cynthia, 80126, Naples, Italy;

3 Department of Pharmacy, University of Naples Federico II, Naples 80138, Italy

*Corresponding author: Luca De Stefano, luca.destefano@cnr.it; Tel.: +390816132490

S1. TB aspecific adsorption

Figure S1. TB interaction monitoring onto bare QR.

TB solution at 100nM was incubated onto bare QR surface in order to detect the aspecific interaction between TB and QR. Results highlight a ∆f of -3Hz. which means that really few TB molecules stopped on QR surface, probably due to weak electrostatic aspecific interactions. Extensive rinsing washes were performed in order to remove TBA-SH molecules not strongly bound to QR surface, and then real-time interaction monitoring with TB molecules was studied.

S2. System regeneration

Figure S2. TB interaction monitoring after oligonucleotides melting.

Reversibility of biosystemsis a key point in biosensors based Lab-On-a-Chip development. In the present study,after three TBA/TB binding cycles, QR surface was rinsed at high temperature (55 °C for 1h) and then used again in QCM set up. Due to experimental condition it was not possible to retrieve the same frequency of QR just after TBA functionalization (i.e., it depends on how the QR is mounted in the QCM).Nevertheless, reversibility can be proved by monitoring interaction with TB: data reported in Figure S1highlightedregeneration of the systemsince on exposure to 20 and 50 nMTBsolutionsa final Δfof about 20 Hz were measured, very close to previous quantification (ca. 24 Hz).

Sensor reversibility was also proved by spectroscopic ellipsometry (data not shown here). The analysis performed on QR surface after rinsing in deionized water at 55 ° C revealed the presence of a biological film of only 3 nm thick. This result demonstrated the removal of TB.

The sample was analyzed again after the interaction with 20 and 50 nM of TB and a thickness increase of 12 nm was estimated.