Quantitative Measures of Reliability and Sensitivity of Nanoparticle-Based Sensors in Detecting Volatile Organic Compounds

Identification of phenol 2,2-methylene bis, 6 [1,1-D] as breath biomarker of hepatocellular carcinoma (HCC) patients and its electrochemical sensing: E-nose biosensor for HCC

BACKGROUND

According to WHO, Hepatocellular cancer (HCC) was the second leading cause of death in 2019 and is gradually increasing. The lipid peroxidation mechanism in cancer cells causes the emission of VOCs in the breath. Volatile organic compounds (VOCs) in breath are becoming favorable biomarkers, especially for cancers, for their sample retrieval and specific association with early metabolic changes. Since both diagnosis and prognosis of the disease depend on the quantity and kind of circulatory biomarkers to be detected, sensitive and selective biosensors with the possibility for portability are constantly in demand.

RESULTS

In this study, breath samples of HCC patients were screened for identification of VOCs via GCMS and later verified by applying unsupervised machine learning models. Phenol 2,2 methylene bis [6-(1,1-dimethyl ethyl)-4-methyl] (MBMBP) was found to be significant VOC in the breath of HCC patients, with a minimum concentration of 2100 ppm. Thiol-modified AuNPs were synthesized, as we reported earlier, and immobilized on the working electrode surface to electrochemically sense MBMBP in purified form and later from clinical breath samples. During the electrochemical experiment of AuNPs with MPMBP, the analyte gets electro-oxidized, whereas the Au (III) ions get reduced to the phenoxy radical's species. The electrochemical analysis of MBMBP detection using hexane thiol AuNPs showed a LOD of 0.005 molL ¹. The thiolated AuNPs-based biosensor for HCC diagnosis via VOC detection confirmed MPMBP in lab standards and raw clinical breath samples of HCC patients.

SIGNIFICANCE

This study reveals that GCE modified with hexanethiol AuNPs for the adsorption of significant breath biomarker, is a potential platform for the development of e-nose sensor for the detection of HCC at early stage.

Volatile Organic Compounds as Potential Biomarkers for Noninvasive Disease Detection by Nanosensors: A Comprehensive Review

Biomarkers are biological molecules associated with physiological changes of the body and aids in the detecting the onset of disease in patients. There is an urgent need for self-monitoring and early detection of cardiovascular and other health complications. Several blood-based biomarkers have been well established in diagnosis and monitoring the onset of diseases. However, the detection level of biomarkers in bed-side analysis is difficult and complications arise due to the endothelial dysfunction. Currently single volatile organic compounds (VOCs) based sensors are available for the detection of human diseases and no dedicated nanosensor is available for the elderly. Moreover, accuracy of the sensors based on a single analyte is limited. Hence, breath analysis has received enormous attention in healthcare due to its relatively inexpensive, rapid, and noninvasive methods for detecting diseases. This review gives a detailed analysis of how biomarker imprinted nanosensor can be used as a noninvasive method for detecting VOC to health issues early using exhaled breath analysis.