(297b) Analysis of Multiplexed Nanosensor Arrays Based on Nir Fluorescent Single Walled Carbon Nanotubes

The high-throughput, label-free detection of biomolecules remains an important challenge in analytical chemistry with the potential of nanosensor technology to significantly increase the ability to multiplex such assays. Herein, we analyze the variance and binding kinetics of a nanosensor array based on fluorescent single wall carbon nanotubes. The nanotubes are non-covalently modified with Cu²⁺ chelator - nitrilotriacetic acid group – to immobilize immunobinding proteins, such as Protein A, G and L as molecular recognition sites. The Cu²⁺ ions also serve as a proximity quencher that when the analyte antibodies bind with the immunobinding proteins, the resulted distance change between the Cu²⁺ ions and the nanotube surface modulates the near IR emission of nanotubes and gives a direct readout. Based on this mechanism, we develop an optical microarray composed of sensor spots about 200 um at a density of ~300 spots/cm², which is capable of real-time and quantitative detection of Mouse IgM, Human IgD and Rat IgG2a, in the concentration range between 125 – 500 ug/mL. Moreover, the binding forward reaction rates can be extracted from the initial binding response, which are significantly different among the recognition sites. In order to perform multiplexed detections, the sensor array is modified with Protein G and Protein L in alternative columns, showing distinct binding affinities with the same analyte, demonstrating the capacity to perform high throughput detection with the optical microarray. In addition to the platform development, we also investigate the spot-spot variance, which is shown to result from the inhomogeneous distribution of nanosensors in the spot during the printing and modification process.