1-Butyl-3-Methylimidazolium Tetrafluoroborate Film as a Highly Selective Sensing Material for Non-Invasive Detection of Acetone Using a Quartz Crystal Microbalance

Sensors for Volatile Organic Compounds

This paper provides an overview of recent developments in the field of volatile organic compound (VOC) sensors, which are finding uses in healthcare, safety, environmental monitoring, food and agriculture, oil industry, and other fields. It starts by briefly explaining the basics of VOC sensing and reviewing the currently available and quickly progressing VOC sensing approaches. It then discusses the main trends in materials' design with special attention to nanostructuring and nanohybridization. Emerging sensing materials and strategies are highlighted and their involvement in the different types of sensing technologies is discussed, including optical, electrical, and gravimetric sensors. The review also provides detailed discussions about the main limitations of the field and offers potential solutions. The status of the field and suggestions of promising directions for future development are summarized.

High-Performance Ketone Sensing in Vapor Phase Enabled by o-Carborane-Modified Cyclometalated Alkynyl-Gold(III) Complex-Based Fluorescent Films

Development of high-performance, low-power-consumption, small-sized detectors is a key issue for fabricating specific miniaturized chromatographs (GCs). Herein, we report, for the first-time, utilization of a film-based fluorescent sensor as a GC detector. In the studies, we designed a new o-carborane derivative of a known cyclometalated alkynyl-gold(III) complex, Au-CB. Unlike the parent gold(III) complex, the newly synthesized Au-CB depicted a remarkable aggregation-induced emission (AIE) property, enabling fabrication of a fluorescent film. The film emission is highly sensitive to the presence of ketones such as acetone, 2-pentanone, 3-pentanone, cyclopentanone, etc., in the air. It was demonstrated that the sensing performance of the film could be further improved by changing the film from a planar structure to a tubular one. Via combination with an earlier reported homemade sensory device, a conceptual film-based fluorescent sensor was developed, which demonstrated instant and fully reversible response to the ketones. The experimental detection limits for cyclohexanone and acetone could be lower than 0.08 and 13.0 ppm, respectively. Moreover, the sensor is super stable, as 24 h continuous illumination resulted in less than 1.0% reduction of the fluorescence emission, 50 successive sensings showed no observable decay in the performance, and more than 1 year of storage had no effect upon the property. Further studies demonstrated that the film sensor could be used as a GC detector with performance comparable to the commercial flame ionization detector (FID), which lays the foundation for future applications in specific miniaturized GCs because of its merits in size, power consumption, carrier gas, etc.

Omics-based biomarkers in the diagnosis of diabetes

Diabetes mellitus (DM) is a group of metabolic diseases related to the dysfunction of insulin, causing hyperglycaemia and life-threatening complications. Current early screening and diagnostic tests for DM are based on changes in glucose levels and autoantibody detection. This review evaluates recent studies on biomarker candidates in diagnosing type 1, type 2 and gestational DM based on omics classification, whilst highlighting the relationship of these biomarkers with the development of diabetes, diagnostic accuracy, challenges and future prospects. In addition, it also focuses on possible non-invasive biomarker candidates besides common blood biomarkers.

Synergy between nanomaterials and volatile organic compounds for non-invasive medical evaluation

This article is an overview of the present and ongoing developments in the field of nanomaterial-based sensors for enabling fast, relatively inexpensive and minimally (or non-) invasive diagnostics of health conditions with follow-up by detecting volatile organic compounds (VOCs) excreted from one or combination of human body fluids and tissues (e.g., blood, urine, breath, skin). Part of the review provides a didactic examination of the concepts and approaches related to emerging sensing materials and transduction techniques linked with the VOC-based non-invasive medical evaluations. We also present and discuss diverse characteristics of these innovative sensors, such as their mode of operation, sensitivity, selectivity and response time, as well as the major approaches proposed for enhancing their ability as hybrid sensors to afford multidimensional sensing and information-based sensing. The other parts of the review give an updated compilation of the past and currently available VOC-based sensors for disease diagnostics. This compilation summarizes all VOCs identified in relation to sickness and sampling origin that links these data with advanced nanomaterial-based sensing technologies. Both strength and pitfalls are discussed and criticized, particularly from the perspective of the information and communication era. Further ideas regarding improvement of sensors, sensor arrays, sensing devices and the proposed workflow are also included.

Design of a novel filter paper based construct for rapid analysis of acetone

The present work was focused to design a cheap, rapid, portable and easy to use filter paper based assay for the qualitative and quantitate analysis of acetone. Sodium alginate gel was loaded with the acetone specific optical signal probe, and subsequently coated onto filter paper surface to design portable colorimetric assays for acetone monitoring. The color of the paper sensor strip was observed to change from dark yellow to light yellowish in the presence of varying concentrations of acetone. Three different color analyzing models including RGB, HSV, and LAB were employed to probe the output optical signal, and their performance was compared in terms of better interpretation of the generated signal. The LAB model was found to provide better analytical figures of merit with a linear response for the acetone concentration ranging from 2.5 to 1500 ppm, and a limit of detection of 0.5 ppm. Furthermore, the specificity of the designed filter paper based sensor was demonstrated against different common interfering compounds. The results demonstrated the potential of our proposed filter paper based sensor as a novel tool for the analysis of acetone.