A cost-effective volume miniaturized and microcontroller based cytochrome c assay

In this paper, a portable, cost-effective electrochemical assay is presented for rapid, sensitive, and quantitative detection of cytochrome c (cyt c) release. The developed cyt c assay consists of two parts: (i) a miniaturized electrochemical biosensor based on cytochrome c reductase (CcR) functionalized screen printed electrodes (SPE); (ii) a microcontroller based data acquisition unit integrated with potentiostat circuit capable of performing cyclic voltammetry technique for the analysis. The working electrode surface of SPE was integrated with polypyrrole (PPy)-carbon nanotubes (CNT) nanocomposite for an enhanced immobilization of the enzyme, CcR. The acquired biosensor data are processed into digital form by the microcontroller and further transferred to a PC through USB port for analysis. GUI based system implemented here makes the analyzer easy to operate. Under optimal conditions, the electroanalytical behavior of the CcR-CNT-PPy-SPE biosensor linearly responds to the cyt c concentration range from 10 nM to 500 μM with a detection limit of 10 nM and a sensitivity of 0.102 ± 0.005 μA μM−1 cm−2. The performance of the volume miniaturized SPE based biosensor coupled with the portable microcontroller based instrument was further evaluated by applying it for the measurement of mitochondrial cyt c release during cardiomyocytes apoptosis; the results are validated well with the commercial electrochemical analyzer and standard ELISA.