Integrated Low Cost Optical Biosensor for High Resolution Sensing of Myeloperoxidase (MPO) Activity Through Carbon Nanotube Degradation

Myeloperoxidase (MPO) is an important biomarker for diseases associated with inflammation, and has been recognized as an early warning biomarker for cardiovascular diseases, with at-risk individuals typically exhibiting MPO concentration >350 ng/ml in blood. We present a high resolution and low cost optical biosensor capable of detecting MPO activity directly through degradation of single walled carbon nanotubes (SWCNTs), without requiring additional probe chemicals or reagents. The optical biosensor is assembled using commercially available semiconductor integrated circuit (IC) components. The change in optical contrast due to degradation of the SWCNTs is measured by a phase sensitive detection circuit as a voltage signal. The sensor system can be operated with merely 2 $\mu \text{l}$ of the test sample, and has sensitivity of 1.39 mV/$\mu \text{g}$ /ml with resolution of 26.8 ng/ml change in SWCNT concentration. The sensor is able to produce appreciable change in sensor output (>100 mV) and detect MPO activity for lyophilized MPO concentration in phosphate-buffered saline (PBS) and hydrogen peroxide (H2O2) as low as 327ng/ml.