Sensitive and selective colorimetric sensing of acetone based on gold nanoparticles capped with l-cysteine

Research progress of electronic nose technology in exhaled breath disease analysis

Exhaled breath analysis has attracted considerable attention as a noninvasive and portable health diagnosis method due to numerous advantages, such as convenience, safety, simplicity, and avoidance of discomfort. Based on many studies, exhaled breath analysis is a promising medical detection technology capable of diagnosing different diseases by analyzing the concentration, type and other characteristics of specific gases. In the existing gas analysis technology, the electronic nose (eNose) analysis method has great advantages of high sensitivity, rapid response, real-time monitoring, ease of use and portability. Herein, this review is intended to provide an overview of the application of human exhaled breath components in disease diagnosis, existing breath testing technologies and the development and research status of electronic nose technology. In the electronic nose technology section, the three aspects of sensors, algorithms and existing systems are summarized in detail. Moreover, the related challenges and limitations involved in the abovementioned technologies are also discussed. Finally, the conclusion and perspective of eNose technology are presented.

Colorimetric acetone sensor based on ionic liquid functionalized drug-mediated silver nanostructures

The current work reports the drug-mediated synthesis of silver nanoparticles (AgNPs) and their functionalization with ionic liquid (IL) for acetone determination. The rationale behind the selection of the Augmentin drug was the aromaticity in its structure and the functional groups attached. These properties are not only supposed to work in the synthesis of the nanoparticles but also enhance their electron density. The nanoparticles were further coated with 1-H-3-methylimidazolium acetate IL, having conductivity and aromaticity in their structure. The synthesized nanoparticles have been characterized by different techniques such as FTIR, XRD, SEM, and EDX. Colorimetric determination of acetone was done by using IL capped AgNPs with the assistance of NaCl solution and results were analyzed by UV-Vis spectrophotometry. Low-cost, stable eosin dye works as a substrate and is consumed resulting in a color change from brown to transparent. The IL capped AgNPs act as a reducing agent for the production of reduced radical form of acetone which act on the carboxylate moiety and bubble it out in the form of CO₂. Different parameters such as (concentrations, loading of nanoparticles, time and pH, etc.) were optimized to get the best results of the proposed sensor. The sensor shows a wide linear range of (1 ×10^-8-2.40 ×10^-6 M), low limit of detection 2.66 × 10^-9 M, and limit of quantification 8.86 × 10^-9 M with an R² value of 0.997. The proposed sensor has been successfully applied to diabetic patient's urine samples for acetone detection with a visible colorimetric change. It showed good sensitivity and selectivity towards acetone detection.

Controlled 3D assembly and stimuli responsive behavior of DNA and peptide functionalized gold nanoparticles in solutions

DNA mediated directed self assembly of gold nanoparticles (AuNPs) has garnered immense interest due to its ability to precisely control supramolecular assemblies. Most experimental works have relied on utilizing the...

Two-dimensional layered WS2 nanosheets as peroxidase mimetics in a colorimetric chemosensor for simple and rapid detection of acetone

Two-dimensional (2D) nanomaterials with catalytic activity have attracted considerable attention from researchers, but their application in the detection of hazardous substances needs to be further expanded. Herein, layered tungsten sulfide (WS₂) nanosheets with peroxidase-mimicking activity were used to construct a colorimetric chemosensor for rapid detection of acetone. WS₂ nanosheets can decompose H₂O₂ to generate hydroxyl radicals (·OH), which will further oxidize o-phenylenediamine (OPD) through hydrogen atom transfer (HAT) to form the yellow product 2,3-diaminophenazine. Acetone can block the HAT from OPD to ·OH, thus causing obvious inhibition of the peroxidase activity of WS₂ nanosheets, making the solution appear pale yellow or even colorless. The investigation of catalytic kinetics indicates that the catalytic reaction consists of the 'ping pong' mechanism, and the regulatory effect of acetone on WS₂ nanosheets is confirmed to be an irreversible inhibition. The chemosensor can easily distinguish a trace amount of acetone by the naked eye in less than 20 min, and has a limit of detection for acetone of as low as 3.08 mg  l^-1. The application in actual samples displays the accuracy and stability of the chemosensor, suggesting that such a method is promising for acetone detection.