Search

This editorial provides an overview and summary of recent research articles published in Biosensors journal, volumes 9 (2019) and 10 (2020), within the Special Issue “Noninvasive Early Disease Diagnosis”, which focused on recent sensors, biosensors, and clinical instruments developed for the noninvasive early detection and diagnosis of human, animal, and plant diseases or invasive pests. The six research articles included in this Special Issue provide examples of some of the latest electronic-nose (e-nose) and related volatile organic compound (VOC)-detection technologies, which are being tested and developed to improve the effectiveness and efficiency of innovative diagnostic methodologies for the early detection of particular diseases and pest infestations in living hosts, prior to symptom development.

The development of new C-320 electronic-nose (e-nose) methods for pre-symptomatic detection of White-Nose Syndrome (WNS) in bats has required efficacy studies of instrument capabilities to discriminate between major sources of volatile organic compounds (VOCs) derived from clinical samples. In this phase-2 study, we further tested this e-nose for capabilities to distinguish between bat species based on differences in whole-body VOC emissions. Live healthy individuals of nine bat species were temporarily captured outside of caves in Arkansas and Louisiana. VOC emissions from bats were collected using newly developed portable air collection and sampling-chamber devices in tandem. Sensor-array output responses to bat VOC emissions were compared to those of 22 pure VOC analytical standards from five chemical classes. Distinct smellprint signatures were produced from e-nose analyses of VOC metabolites derived from individual bat species. Smellprint patterns were analyzed using 2-dimensional and 3-dimensional Principal Component Analysis (PCA) to produce aroma map plots showing effective discrimination between bat species with high statistical significance. These results demonstrate potential instrument efficacy for distinguishing between species-specific, bat-derived VOC metabolite emissions as major components of clinical samples collected from bats in caves for disease detection prior to symptom development. This study provided additional information required to fully test the efficacy of a portable e-nose instrument for diagnostic applications in subsequent phase-3 testing of noninvasive, early WNS disease detection in intra-cave hibernating bats.

A new frontier in clinical disease diagnostics was launched by a series of recent discoveries of a new phenomenon that makes important connections between the metabolic activities of resident microbes and human diseases. Numerous recent studies have demonstrated that the mechanisms leading to disease development involve not only pathogenesis, but also activities and interactions between the complex assemblage of microbes (microbiota) in the oral cavity, lungs, and gut, the microbial metabolites they produce, and the host immune system. These interactions may occur by either metabolism-dependent or metabolism-independent pathways. Consequently, dysbiosis or changes in microbiota composition, often modulate disease development by at least two different mechanisms, including disease-induced dysbiosis and alterations in dysbiotic patterns caused by abiotic, exogenous factors (diet, drug use, and various environmental factors). This paper summarizes recent evidence demonstrating how electronic-nose (e-nose) technologies with multisensor arrays could potentially be used to identify specific changes in microbiome composition, microbiome diversity, and related alterations in patterns of metabolic pathways at different locations in the body. This could be achieved through detections and discriminations between specific chemical VOC-biomarkers, products of microbial metabolism, identified in healthy patients and those related to dysbiosis associated with specific diseases. Recent advances in e-nose technologies, having capabilities of detecting complex mixtures of VOC-metabolites in the headspace of clinical samples, offer new tools for exploiting the common occurrence of microbial dysbiotic mechanisms for noninvasive early disease detection.

Fruits produce a wide range of volatile organic compounds that impart their characteristically distinct aromas and contribute to unique flavor characteristics. Fruit aroma and flavor characteristics are of key importance in determining consumer acceptance in commercial fruit markets based on individual preference. Fruit producers, suppliers and retailers traditionally utilize and rely on human testers or panels to evaluate fruit quality and aroma characters for assessing fruit salability in fresh markets. We explore the current and potential utilization of electronic-nose devices (with specialized sensor arrays), instruments that are very effective in discriminating complex mixtures of fruit volatiles, as new effective tools for more efficient fruit aroma analyses to replace conventional expensive methods used in fruit aroma assessments. We review the chemical nature of fruit volatiles during all stages of the agro-fruit production process, describe some of the more important applications that electronic nose (e-nose) technologies have provided for fruit aroma characterizations, and summarize recent research providing e-nose data on the effectiveness of these specialized gas-sensing instruments for fruit identifications, cultivar discriminations, ripeness assessments and fruit grading for assuring fruit quality in commercial markets.