Label-free real time optical detection of binding of living cells and biopolymers

Abstract

Biosensor based on long range surface waves on one-dimentional photonic crystal (PC) surface in microfluid channel was used to detect binding of cells, viruses, nanoparticles and proteins. Covalent attachment of biopolymers to polyaminated PC with glutaraldehyde cross-linking in microfluid channel results in functionally active proteins, living eukaryotic, bacterial cells and viruses. The evident advantages of the optical biosensor include native conformations of biopolymers, detection of reversible or permanent specific binding with ligands, broad detection scale from eukaryotic cells to low-molecular-weight ligands and observations in real time with possible calculations of affinity and kinetic constants. However, relatively low sensitivity limit near 0.1 μg/ml of proteins is significantly less those of ELISA and xMAP immunofluorescent analysis (approximately 1 pg/ml). Integral adlayer thickness does not reveal molecular events on each cell with possible variations. The label-free real-time optical detection allowed us to estimate cytotoxicity of currently used and novel drugs and to explore the antiviral properties of new compounds.