Abstract

Highly-Sensitive Label-Free Optical Biosensors and Multiplex Immuno-Magnetic Platform for Point-of-Care Diagnostics

Petr Nikitin, Prof and Head of Laboratory, Prokhorov General Physics Institute, Russian Academy of Sciences

Several types of original biosensors will be presented. Intelligent biosensing systems are developed based on nanoparticles that can employ molecular interactions to perform any Boolean logic function. These systems are efficiently used for logic-gated biosensing with lateral flow test-strips and 3D filters. Besides, multichannel label-free biosensors are designed based on the spectral correlation interferometry (SCI) for detection of various analytes by measuring changes in thickness of a biolayer on functionalized glass slips used as affordable single-use sensor chips. The SCI method is not sensitive to bulk refractive index of a solution under test and provides signals in metrological units (pm or nm). Using real-time monitoring of bioreactions by the SCI, a new multiplex dry-reagent immunomagnetic (DRIM) biosensing platform is developed for rapid high-precision quantitative analyses of complex mediums. It is based on the highly sensitive magnetic particle quantification (MPQ) method that provides detection limit of 60 zeptomoles or 0.4 ng of magnetic nanolabels and extremely wide linear dynamic range of 7 orders. The DRIM platform has permitted the detection in human serum of as low as 25 pg/ml total prostate specific antigen during 30-min assay. The featured 3-fold signal increase per every order of concentration within 3.5 orders of magnitude allows precise analysis of antigen concentrations in a wide range. In addition, based on the MPQ technique, a new cytometry method has been developed and successfully tested for rapid assessment of cancer HER2/neu status of cells, for estimation of expression level of various antigens on cell surfaces and cancer diagnostics.