Detection of anti-SARS CoV-2 antibodies in human serum by means of Bloch surface waves on 1D photonic crystal biochips
Agostino Occhicone, Alberto Sinibaldi, Daniele Chiappetta, Paola Di Matteo, Tommaso Pileri, Norbert Danz, Frank Sonntag, Peter Munzert, Matteo Allegretti, Valentina De Pascale, Chiara Mandoj, Francesco Michelotti
Abstract
This study presents the development and characterization of a disposable biochip for the detection of antibodies against the SARS-CoV-2 spike protein, a well-known target for vaccine and therapeutic development. This biochip is based on a one-dimensional photonic crystal (1DPC) deposited on a plastic substrate and designed to sustain Bloch surface waves (BSW) in the visible range. The experimental phase was carried out using the biochip in conjunction with a custom-made optical read-out platform capable of real-time refractometric detection and fluorescence-based end-point measurements. Our biochip was functionalized by immobilizing the receptor-binding domain of the spike protein onto the surface using a silanization process. Human serum samples, including a negative control and a positive sample from a recovered COVID-19 patient, were tested on the biochip. The experimental results show that the biochip discriminates between positive and negative samples in a label-free refractometric mode down to a 1:10 dilution of the sera and in quantum dot amplified refractometric and fluorescence mode down to 1:100 dilution. The results demonstrate the potential of the disposable biochip for sensitive and specific detection of COVID-19 antibodies.