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Nowadays, in the clinical, pharmaceutical, and environmental sectors, the development of facile and sensitive analytical methods and/or innovative devices for the follow-up and detection of antibiotics and pharmaceutical formulations, in general, are urgently needed and still challenging. This work declared three vital applications for broad-spectrum nitrofurantoin (macrofuran) antibiotic detection and quantification: A colorimetric method, a coated paper strip-based nano-lanthanum complex prototype and fabrication of smart electronic color sensor device-based coated paper strips. The colorimetric method showed a significant response upon increasing the concentration of the nitrofurantoin in a range between (1.0–100.0 ng/mL) via a visual color change from orange-yellow to red colors degree with detection and quantification limits of 0.175 and 0.53 ng/mL, respectively, whereas the nano-lanthanum complex coated paper strip prototype showed qualitative on-site sensing for nitrofurantoin via naked eye color changes which can be detected anywhere. Moreover, a smart prototype for detecting macrofuran in the means of paper color change in the RGB color component extraction algorithm and the grayscale projection value processing algorithm was fabricated. The change in RGB color on the coated paper strip was detected using an electronic color sensor device. The developed colorimetric method, coated paper strip, and the electronic color sensor device prototype exhibited fast, simple, costless, and selective towards macrofuran over the competing analyzed. As well as, showed good applicability in the different real samples spiked with different concentrations of macrofuran. [ABSTRACT FROM AUTHOR]

Bacillus cereus is one of the most common foodborne pathogens found in various kinds of staple foods such as rice and wheat. A rapid and accurate detection method for this pathogen is highly desirable for the sustainable production of relevant food products. While several classical and molecular-based detection methods are available for the identification of B. cereus, they suffered one or more limitations such as the requirement for a tedious and time-consuming process, less than ideal specificity, and the lack of portability. Herein, we developed the first paper-based sensing device that exhibits high species specificity with sufficiently low limit of detection for the visual detection of specific DNA sequences of B. cereus. The success is attributed to the strategic planning of fabrication in various dimensions including thorough bioinformatics search for highly specific genes, the use of the pyrrolidinyl peptide nucleic acid (PNA) probe whose selectivity advantage is well documented, and an effective PNA immobilization and DNA-binding visualization method with an internal cross-checking system for validating the results. Testing in rice matrices indicates that the sensor is capable of detecting and distinguishing B. cereus from other bacterial species. Hence, this paper-based sensor has potential to be adopted as a practical means to detect B. cereus in food industries. [ABSTRACT FROM AUTHOR]

Importantly, trends and developments of this interaction found in both biosensors and bioassays have opened new perspectives in the sensing field and are therefore also of great interest to the sensor community. (i) Biosensors are chemical sensors in which the recognition system utilizes a biochemical mechanism for the interaction process in/at the recognition layer. [Extracted from the article]

In this paper, we proposed an efficient method for mercury(II) and glutathione detection using a fluorescent nanoprobe as a sensor. Carbon dots were synthesized from polyethyleneimine and ammonium citrate via a one-step hydrothermal method. The fluorescence of carbon dots was quenched since electron transfer occurred due to the interaction between mercury(II) and functional groups on the surface of carbon dots. Adding glutathione to the carbon dots-mercury(II) system, the fluorescence was recovered due to the stronger binding ability of glutathione to mercury(II). Based on the above-mentioned principle, this "off-on" fluorescent sensor can easily achieve the detection of mercury(II) and glutathione, which provided limits of detection of 22.45 nM and 61.89 nM, respectively. In this paper, the proposed method has been applied to detect mercury(II) and glutathione in real lake water and serum, respectively, and a logic gate for sensing glutathione was presented. The developed "off-on" fluorescent sensor with high sensitivity and selectivity has shown great potential for mercury(II) and glutathione detection in environmental and biosensing fields. [ABSTRACT FROM AUTHOR]

In this work, green-emitting carbon quantum dots were successfully prepared through a facile one-step solid-state reaction method. The obtained green-emitting carbon dots (G-CDs) showed good fluorescence stability in NaCl aqueous solution and different pH values. Moreover, the G-CDs showed high sensitivity and selectivity for detecting hypochlorite by both fluorometry and colorimetry. Under the optimized condition, a highly sensitive detection of hypochlorite was established in the range of 0.2–100 μM and 10–150 μM for fluorescent and colorimetric methods, respectively. The corresponding limits of detection (LOD) were 0.0781 μM and 1.82 μM, respectively. Therefore, the G-CDs were successfully applied to determinate hypochlorite in actual water samples. In addition, a paper-based sensor loading with the G-CDs was also developed for rapid visual detection of hypochlorite. The results suggested that the G-CDs could be a promising candidate to detect hypochlorite. [ABSTRACT FROM AUTHOR]

Concerns about environmental and food contamination caused by chlortetracycline (CTC) residues have prompted people to explore efficient and convenient CTC monitoring platforms. However, the reported fluorescent probes generally fail to selectively detect CTC due to the structural similarity of tetracycline antibiotics. Herein, an intrinsic dual-emission carbon dots (D-CDs) ratiometric fluorescence sensor was prepared for highly sensitive and selective determination of CTC over other tetracyclines by one-step synthesis. The sensor exhibited a significant fluorescence enhancement at 425 nm after introducing CTC. The fluorescence "turn on" of the sensing system is due to aggregation-induced emission (AIE) phenomenon formed by hydrogen bonds and π conjugation promoting the specific recognition of CTC by D-CDs. The linear detection varied from 0.98 to 143.67 ng mL−1 with a low limit of detection (LOD) of 1.29 ng mL−1 (R2 = 0.998), which was lower than most reported in the literature. The D-CDs sensor was applied to detect CTC in spiked milk, blocked normal human serum, and fish samples with recoveries of 95.5–104.2% and relative standard deviations (RSDs) of 2.6%. Particularly, D-CDs based test papers with a smartphone were prepared for portable and visual detection of CTC by analyzing the various color changes of RGB of fluorescence color, with an LOD of 7.18 ng mL−1 (R2 = 0.9909). The fluorescence sensor designed in this work could be used as a rapid tool with high performance and selectivity for monitoring control in foods. [ABSTRACT FROM AUTHOR]

Concerns about environmental and food contamination caused by chlortetracycline (CTC) residues have prompted people to explore efficient and convenient CTC monitoring platforms. However, the reported fluorescent probes generally fail to selectively detect CTC due to the structural similarity of tetracycline antibiotics. Herein, an intrinsic dual-emission carbon dots (D-CDs) ratiometric fluorescence sensor was prepared for highly sensitive and selective determination of CTC over other tetracyclines by one-step synthesis. The sensor exhibited a significant fluorescence enhancement at 425 nm after introducing CTC. The fluorescence "turn on" of the sensing system is due to aggregation-induced emission (AIE) phenomenon formed by hydrogen bonds and π conjugation promoting the specific recognition of CTC by D-CDs. The linear detection varied from 0.98 to 143.67 ng mL−1 with a low limit of detection (LOD) of 1.29 ng mL−1 (R2 = 0.998), which was lower than most reported in the literature. The D-CDs sensor was applied to detect CTC in spiked milk, blocked normal human serum, and fish samples with recoveries of 95.5–104.2% and relative standard deviations (RSDs) of 2.6%. Particularly, D-CDs based test papers with a smartphone were prepared for portable and visual detection of CTC by analyzing the various color changes of RGB of fluorescence color, with an LOD of 7.18 ng mL−1 (R2 = 0.9909). The fluorescence sensor designed in this work could be used as a rapid tool with high performance and selectivity for monitoring control in foods. [ABSTRACT FROM AUTHOR]

Although some ratiometric fluorescent sensors have been reported to detect tetracyclines, most of ratiometric fluorescent sensors were established based on europium ion with a narrow linear range. In this work, a ratiometric fluorescent sensor for tetracyclines detection was established based on the dual-emission lanthanum-doped carbon dots (La-CDs) as probes combining with the characteristic pH-response of tetracyclines. The fluorescence intensity of tetracyclines will be enhanced in high pH, and the emission peak of tetracyclines overlapped with the peak of probes. The superposition effect of tetracyclines and probes at 515 nm greatly improved the sensitivity of the ratiometric fluorescent sensor and widened the detection range, and linear ranges for oxytetracycline (OTC) and tetracycline (TC) were respectively 0.00–805.20 μM and 0.00–1039.50 μM. Moreover, the preparation procedure of the La-CDs was simple and time saving and the coupling agent was not required. A comparison of La-CDs with undoped carbon dots (un-CDs) showed that the optical performance and sensing performance of La-CDs were improved. In addition, a portable paper sensor with La-CDs as probes was preliminarily explored in this work, and the sensor has been applied to detect OTC and TC in pork and fish with satisfactory results. [ABSTRACT FROM AUTHOR]

Development of new capillary electrophoresis (CE) methodology and instrumentation, as well as application of CE to solve new problems, remains an active research area because of the attractive features of CE compared to other separation techniques. In this review, we focus on the representative works about sample preconcentration, separation media or capillary coating development, detector construction, and multidimensional separation in CE, which are judiciously selected from the papers published in 2018–2020. [ABSTRACT FROM AUTHOR]