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A method using pH gradient to modify the phospholipid dissociation has been developed using hybrid magnetoliposomes with encapsulated enzyme laccase, which has been immobilized on hydrophilic magnetic nanocrystals (PAA-MNCs) retained in the reaction/detection zone of a microfluidic system. The hybrid magnetoliposomes act as micro containers, providing the safe transfer of the enzyme to the reaction/detection site, where it is retained, and preconcentration of the enzyme in this place occurs, which improves the system's sensitivity. The use of pH change involves the lack of external molecules to release the encapsulated materials. The laccase-mediated redox oxidation of the fluorescent substrate 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) to form its non-fluorescent oxide form has been used as the indicator reaction. The method was applied to determine potential laccase inhibitors in beverages and fruits. The study of the inhibitory effect has focused on compounds that follow different mechanisms: cysteine, malic acid, and fumaric acid. The dynamic ranges of the calibration graphs of these compounds were between 0.05–100, 0.02–100, and 0.1–100 μmol L−1, respectively. The detection limits have been established between 6 and 30 nmol L−1, and the precision expressed as the percent of relative standard deviation (RSD%) was between 2.5 and 5.1%. The overall microfluidic system showed a sampling frequency of 8 h−1. The method has been applied to determine fumaric acid as a laccase inhibitor in several juice samples (apple, pear, and grape), with recovery values between 85 and 101%. The results were comparable to those obtained using a LC reference method. [ABSTRACT FROM AUTHOR]

An inverted DNA tetrahedron–mediated modular DNA walker was developed for the determination of sulfadimethoxine. The inverted DNA tetrahedron scaffold raises several advantages of recognition module including appropriate lateral space, multiple recognition domains, and cost-effectiveness. The proposed inverted DNA tetrahedron-based recognition module exhibited better binding affinity and kinetics toward target antibiotic than that of other DNA tetrahedron counterparts. Upon specific binding with target, the released bipedal DNA walking strand hops to the signal amplification module and moves stochastically with assistant of nicking enzyme. By coupling these two modules, a good linear relationship between the fluorescence intensity of supernatant and the concentration of sulfadimethoxine was achieved in the range 0.1–100 nM, and the limit of detection was 64.7 pM. Furthermore, this modular DNA walker had also successfully applied to spiked honey and milk samples with satisfactory recoveries from 91.5 to 108.8%, demonstrating its practical sensing capability. [ABSTRACT FROM AUTHOR]

Industrialization has led to environmental pollution with various hazardous chemicals including pollution with metals. In this regard, the development of highly efficient analytical methods for their determination has received considerable attention to ensure public safety. Currently, scientists are paying more and more attention to the automation of analytical methods, since it permits fast, accurate, and sensitive analysis with minimal exposure of analysts to hazardous substances. This review discusses the automated methods with fluorescent detection developed for metal determination since 2000. It is evident that flow-injection analysis (FIA) with no preconcentration or with solid-phase preconcentration are predominant compared to liquid-phase preconcentration systems. FIA systems are also more widespread than sequential injection analysis (SIA) systems. Moreover, a significant number of works have been devoted to chromatography-based methods. Atomic fluorescence detectors significantly prevail over molecular fluorescence detectors. It must be highlighted that most of the methods result in good figures of merit and performance characteristics, demonstrating their superiority in comparison with manual systems. [ABSTRACT FROM AUTHOR]

Aim: Fluorescence detection of breast and prostate cancer cells expressing Tn-antigen, a tumor marker, with Vicia villosa lectin (VVL)-labeled nanoparticles. Materials & methods: Breast and prostate cancer cells engineered to express high levels of Tn-antigen and non-engineered controls were incubated with VVL-labeled or unlabeled red dye-doped silica-coated polystyrene nanoparticles. The binding to cells was studied with flow cytometry, confocal microscopy, and electron microscopy. Results: Flow cytometry showed that the binding of VVL-labeled nanoparticles was significantly higher to Tn-antigen-expressing cancer cells than controls. Confocal microscopy demonstrated that particles bound to the cell surface. According to the correlative light and electron microscopy the particles bound mostly as aggregates. Conclusion: VVL-labeled nanoparticles could provide a new tool for the detection of Tn-antigen-expressing breast and prostate cancer cells. Graphical Abstract Article highlights New VVL-labeled fluorescent red dye-doped silica-coated PS particles were developed and tested for detection of Tn-antigen, expressed only in malignant cells. Breast and prostate cancer cell lines gene-engineered to express Tn-antigen at a high level and non-engineered counterparts were used as models. The VVL-labeled particles bound specifically and effectively to Tn-antigen-expressing cells compared with their control cells as shown by flow cytometry. Confocal microscopy showed that the VVL-labeled particles were bound to the cell surface of target cells, mostly as aggregates. Further optimization to increase the intensity of the fluorescence and decrease the aggregation tendency of particles would help detect single particles. The VVL-labeled nanoparticles could be used for recognizing Tn-antigen-expressing cells (circulatory tumor cells) in blood samples of breast and prostate cancer patients, biopsies, or cryosections of tumor samples. In the future, they could also be developed to function in vivo as carriers for targeted therapy of Tn-antigen-expressing cancer. [ABSTRACT FROM AUTHOR]

[Display omitted] • ETTA-DFP@TCBP-HOF in situ one-spot preparation of ETTA-DFP COF to TCBP-HOF. • ETTA-DFP@TCBP-HOF for both monitoring and adsorbing 4-nitrophenol (4-NP) and metamitron (MET) • ETTA-DFP@TCBP-HOF with dual-emission for sensing 4-NP and MET with different response modes. • ETTA-DFP@TCBP-HOF with desirable specific surface area for efficient removal of 4-NP and MET. A multifunctional COF@HOF (ETTA-DFP@TCBP-HOF) composite is prepared by adding red-fluorescent ETTA-DFP COF to the blue-fluorescent TCBP-HOF preparation system through molecular hydrogen bonding or π − π stacking interactions in situ one-pot synthesis. ETTA-DFP@TCBP-HOF is a multifunctional material for the quantitative detection and simultaneous adsorption of 4-nitrophenol (4-NP) and metamitron (MET) in aqueous solution. As a dual-emission fluorescent sensor, the ETTA-DFP@TCBP-HOF has both fluorescence of TCBP-HOF at 474 nm and ETTA-DFP COF at 592 nm, which shows a ratiometric response to 4-NP and MET with high selectivity, good sensitivity, good anti-interference performance and fast response. As a adsorbent, ETTA-DFP@TCBP-HOF displays rapid adsorption kinetics, and acceptable adsorption capacity for 4-NP and MET. In conclusion, this work constructs a novel multifunctional hybrid material with dual-emission center of HOF and COF, which can not only be used as a ratiometric fluorescent probe for detection, but also for removal of hazardous pollutants, suggesting a new strategy for environmental remediation and human health. [ABSTRACT FROM AUTHOR]

A novel assay was developed based on a turn-off fluorescent probe using the in situ generation of carbon dots (CDs) by means of UV/H2O2 advanced oxidation of carbohydrates for the detection of bisphenol A (BPA) in food. Different parameters involved in the synthesis of CDs for the direct recognition of BPA have been optimised and a sensing mechanism is outlined. The presence of H2O2 during CD synthesis causes a fluorescence enhancement due to the action of highly oxidant HO· radicals formed throughout the photochemical reaction. Phenolic compounds such as BPA can be easily degraded by the UV/H2O2 oxidation process, acting as a HO· free radical scavengers. This results in a decrease in the fluorescence that can be related to the BPA concentration. Under optimal conditions, a detection limit of 15 µg/kg of BPA and a quantification limit of 46 µg/kg of BPA in food samples were obtained. The repeatability and reproducibility, expressed as relative standard deviation and obtained for two concentration levels (30 µg/kg and 200 µg/kg, n = 5), were less than 2.0% and 6.4%, respectively. The proposed procedure was applied to the analysis of five samples of canned foods (sweet corn, peas, mushrooms, cockles and natural tuna), obtaining concentrations in the range 29.8–49.9 µg/kg of sample. Recovery studies were conducted at two concentration levels (100 and 400 µg BPA/kg of sample), resulting in recoveries in the range 99–101%. Method validation against two certified reference materials was also successfully performed. The experimental results demonstrate that the novel approach is suitable for the detection and quantification of BPA in canned foods. [ABSTRACT FROM AUTHOR]

A reusable fluorescent nanoprobe was developed using DNA-functionalized metal-organic framework (MOF) for ratiometric detection of Hg2+. We utilized a zirconium-based MOF (UiO-66) to encapsulate tris(bipyridine) ruthenium(II) chloride (Ru(bpy)32+), resulting in Ru(bpy)32+@UiO-66 (RU) with red fluorescence. The unsaturated metal sites in UiO-66 facilitate the attachment of thymine-rich single-strand DNA (T-ssDNA) through Zr-O-P bond, producing T-ssDNA-functionalized RU complex (RUT). The T-ssDNA selectively binds to Hg2+, forming stable T-Hg2+-T base pairs and folding into double-stranded DNA, which permits the intercalation of SYBR Green I (SGI) and activates its green fluorescence. In the presence of Hg2+, SGI fluorescence increases in a dose-dependent manner, while Ru(bpy)32+ fluorescence remains constant. This fluorescence contrast enables RUT to serve as an effective ratiometric nanoprobe for Hg2+ detection, with a detection limit of 3.37 nM. Additionally, RUT demonstrates exceptional reusability due to the ability of cysteine to remove Hg2+, given its stronger affinity for thiol groups. The RUT was successfully applied to detect Hg2+ in real water samples. This work advances the development of ratiometric fluorescence nanoprobe based on DNA-functionalized MOFs. [ABSTRACT FROM AUTHOR]

Antioxidants are substances that have the ability to resist or delay oxidative damage. Antioxidants can be used not only for the diagnosis and prevention of vascular diseases, but also for food preservation and industrial production. However, due to the excessive use of antioxidants, it can cause environmental pollution and endanger human health. It can be seen that the development of antioxidant detection technology is important for environment/health maintenance. It is found that traditional detection methods, including high performance liquid chromatography, gas chromatography, etc., have shortcomings such as cumbersome operation and high cost. In contrast, the nanozyme-based detection method features advantages of low cost, simple operation, and rapidity, which has been widely used in the detection of various substances such as glucose and antioxidants. This article focuses on the latest research progress of nanozymes for antioxidant detection. Nanozymes for antioxidant detection are classified according to enzyme-like types. Different types of nanozyme-based sensing strategies and detection devices are summarized. Based on the summary and analysis, one can find that the development of commercial nanozyme-based devices for the practical detection of antioxidants is still challenging. Some emerging technologies (such as artificial intelligence) should be fully utilized to improve the detection sensitivity and accuracy. This article aims to emphasize the application prospects of nanozymes in antioxidant detection and to provide new ideas and inspiration for the development of detection methods. [ABSTRACT FROM AUTHOR]

Setophoma terrestris is an important phytopathogenic fungus listed by China as a harmful fungus subject to phytosanitary import control. This pathogen is a threat to a wide range of plants, particularly as the causal agent of onion pink root rot, one of the most severe diseases of onions. In order to provide rapid identification and early warning of S. terrestris and prevent its spread, we have developed a rapid, accurate, and visually intuitive diagnostic assay for this pathogen, by utilizing recombinase polymerase amplification (RPA), coupled with CRISPR/Cas12a cleavage and fluorescence-based detection systems or paper-based lateral flow strips. The developed RPA-CRISPR/Cas12a assay exhibited remarkable specificity for the detection of S. terrestris. Moreover, this protocol can detect the pathogen at a sensitivity level of 0.01 pg/μL, which significantly outperforms the 1 pg/μL sensitivity achieved by the existing qPCR-based detection method. The entire diagnostic procedure, including DNA extraction, the RPA reaction, the Cas12a cleavage, and the result interpretation, can be accomplished in 40 min. Furthermore, the successful application of the assay in infected plant samples highlighted its potential for rapid and accurate pathogen detection in agricultural settings. In summary, this RPA-CRISPR/Cas12a diagnostic method offers a potentially valuable technological solution for quarantine and disease management. [ABSTRACT FROM AUTHOR]

Avian Leukosis Virus (ALV) is a retrovirus that induces immunosuppression and tumor formation in poultry, posing a significant threat to the poultry industry. Currently, there are no effective vaccines or treatments for ALV. Therefore, the early diagnosis of infected flocks and farm sanitation are crucial for controlling outbreaks of this disease. To address the limitations of traditional diagnostic methods, which require sophisticated equipment and skilled personnel, a dual-tube detection method for ALV-J based on reverse transcription isothermal amplification (RAA) and the CRISPR-Cas13a system has been developed. This method offers the advantages of high sensitivity, specificity, and rapidity; it is capable of detecting virus concentrations as low as 5.4 × 100 copies/μL without cross-reactivity with other avian viruses, with a total testing time not exceeding 85 min. The system was applied to 429 clinical samples, resulting in a positivity rate of 15.2% for CRISPR-Cas13a, which was higher than the 14.7% detected by PCR and 14.2% by ELISA, indicating superior detection capability and consistency. Furthermore, the dual-tube RAA-CRISPR detection system provides visually interpretable results, making it suitable for on-site diagnosis in remote farms lacking laboratory facilities. In conclusion, the proposed ALV-J detection method, characterized by its high sensitivity, specificity, and convenience, is expected to be a vital technology for purification efforts against ALV-J. [ABSTRACT FROM AUTHOR]

A novel analytical method based on ultra-fast liquid chromatography using fluorimetric detector was developed and validated for determination of non-steroidal anti-inflammatory drugs (NSAIDs) (ibuprofen (IBP), etodolac (ETD), dexketoprofen (DKP), sodium diclofenac (SDCF), and naproxen (NPX) in tap water, urine and pharmaceutical samples. Precolumn derivatisation of targeted NSAIDs was carried out with 4-bromomethyl-7-methoxy coumarin (BrMmC) using dibenzo-18-crown-6-ether as reaction catalyst leading to the formation of a fluorescent compound. The obtained fluorescent compound of NSAIDs were measured at excitation wavelength as 325 nm, and emission wavelength of 395 nm. Optimum analytical conditions were carefully studied and improved. C18 column, with the dimensions of 4.0 × 100 mm and 3 µm particle size, was used. Gradient elution with methanol: water 40:60; v/v (eluent A) and acetonitrile 100% (eluent B) were used as mobile phase and flow rate of 0.4 mL/min. The linearity range of the analytes were between 0.01–10.0 µg mL−1. Recovery values obtained from pharmaceutical preparations were found as 100.04%, 99.99%, 100.09%, 99.98% and 100.47% for IBP, ETO, DKP, SDCF, NPX, respectively. LOD values were found to vary between 0.00009 µg mL−1 and 0.00048 µg mL−1 in tap water, urine and pharmaceutical samples. The optimised technique was successfully applied for the determination of NSAIDs in tap water, urine, and pharmaceutical specimen. The specified NSAIDs were not found in real tap water samples. [ABSTRACT FROM AUTHOR]

All-inorganic perovskite quantum dots have sparked a research boom due to their excellent optical properties, however, their own strong ionicity and lead toxicity have hindered further development in the field of sensing. In this study, we have solved the toxicity problem of lead-based perovskite quantum dots by replacing lead with green metal bismuth. Meanwhile, due to the ligand-passivation effect of oleylamine and oleic acid, we successfully synthesized highly stable bismuth-based perovskite quantum dots(Cs3Bi2Br9 PQDs)in ethanol, and constructed the environment-friendly fluorescence sensor for the quantitative detection of oxytetracycline (OTC) for the first time. The results demonstrated that the fluorescence quenching degree of Cs3Bi2Br9 PQDs showed a good linear relationship with the concentration of OTC within the range of 2.0 ~ 18 µM, and the detection limit was 0.432 µM. By studying fluorescence lifetime, absorption spectroscopy, and evaluation of internal filtration parameters, it was proved that the sensing mechanism was caused by the inner filter effect owing to the overlapping of fluorescence emission spectrum of Cs3Bi2Br9 PQDs and UV absorption spectrum of OTC. Moreover, Cs3Bi2Br9 PQDs fluorescent sensor had good selectivity and anti-interference ability. It is believed that this work will open up a new way for lead-free perovskite quantum dots fluorescence sensor in the field of analytical detection. [ABSTRACT FROM AUTHOR]

A fluorescence detection system for high-pressure experiments was developed. The system pressurizes a diamond anvil cell (DAC) with a stepper motor and acquires impression images and external pressure measurements. Fluorescence images and spectra of the sample are collected by a separate module in the instrument. During experiments, the DAC does not need to be continuously removed and placed back in the instrument for further pressurizing or sample detection. All operations are performed under software control so that pressure inaccuracies caused by manual operations are mitigated. By automatic operation, the detection time at each pressure can be reduced to less than 1 min, which greatly reduces the time required. This instrument can replace several commonly used commercial instruments and is more convenient for high-pressure studies. It will become a powerful tool for in situ examination of samples under high pressure. [ABSTRACT FROM AUTHOR]

Abstract One of the important problems in the environment is heavy metal pollution, and fluorescence is one of the best methods for their detection due to its sensitivity, selectivity, and relatively rapid and easy operation. In this study, 1,8-diaminonaphthalene functionalized super-stable mesoporous silica (DAN-LUS-1) was synthesized and used as a fluorescence probe to identify Hg2+ and Fe3+ in food samples. The TGA and FT-IR spectra illustrated that 1,8-diaminonaphthalene was grafted into LUS-1. XRD patterns verified that the LUS-1 and functionalized mesoporous silica have a hexagonal symmetrical array of nano-channels. SEM images showed that the rod-like morphology of LUS-1 was preserved in DAN-LUS-1. Also, surface area and pore diameter decreased from 824 m2 g⁻1 and 3.61 nm for the pure LUS-1 to 748 m2 g⁻1 and 3.43 nm for the DAN-LUS-1, as determined by N₂ adsorption–desorption isotherms. This reduction demonstrated that 1,8-diaminonaphthalene immobilized into the pore of LUS-1. The DAN-LUS-1 fluorescence properties as a chemical sensor were studied with a 340/407 nm excitation/emission wavelength that was quenched by Hg2+ and Fe3+ ions. Hg2+ and Fe3+ were quantified using the fluorescence response in the working range 8.25–13.79 × 10–6 and 3.84–10.71 × 10–6 mol/L, with detection limits of 8.5 × 10–8 M and 1.3 × 10–7 M, respectively. Hg2+ and Fe3+ were measured in vetiver grass and spinach. Since the Fe3+ quenching can move in the opposite direction with sodium hexametaphosphate (SHMP) as a hiding compound for Fe3+, consequently, the circuit logic system was established with Fe3+, Hg2+, and SHMP as inputs and the fluorescent quench as the output.

Single-level biomarker detection has the limitation of insufficient accuracy in cancer diagnosis. Therefore, the strategy of developing highly sensitive, multi-channel biosensors for high-throughput ctDNA determination is critical to improve the accuracy of early diagnosis of clinical tumors. Herein, in order to achieve efficient detection of up to ten targets for early diagnosis of ovarian cancer, a DNA-nanoswitch-based multi-channel (DNA-NSMC) biosensor was built based on the multi-module catalytic hairpin assembly-mediated signal amplification (CHA) and toehold-mediated DNA strand displacement (TDSD) reaction. Only two different fluorescence signals were used as outputs, combined with modular segmentation strategy of DNA-nanoswitch-based reaction platform; the multi-channel detection of up to ten targets was successfully achieved for the first time. The experimental results suggest that the proposed biosensor is a promising tool for simultaneously detecting multiple biomarkers for the early diagnosis of ovarian cancer, offering new strategies for the early screening, diagnosis, and treatment not only for ovarian cancer but also for other cancers. [ABSTRACT FROM AUTHOR]

A novel "turn-on" aptasensor for kanamycin (Kana) detection based on a new Förster resonance energy transfer (FRET) pair is reported. A new organic small molecule was employed as a high-efficiency quencher for fluorophore. Based on specific interactions between ssDNA and the quencher, an ingenious and amplified strategy was designed. In the absence of the target, the fluorescence of the fluorophore labeled at the end of the aptamer was quenched. After the binding of the aptamer to the target, the fluorescence was recovered and amplified. The proposed aptasensor showed high specificity, selectivity, and stability in complicated systems. With the P3-based strategy, the limit of detection for Kana is estimated to be 10 nM, which is much lower than the maximum allowable concentration in milk. The recoveries of spiked Kana in milk were in the range 99.8 ~ 105.3% (n = 3). Fortunately, this novel method can be easily extended to other antibiotics such as tobramycin by simply replacing the aptamer, showing great potential as a universal platform for selective, sensitive, and rapid detection of hazardous analytes in food samples. [ABSTRACT FROM AUTHOR]

Tetracycline (TC) has been widely used in clinical medicine and animal growth promotion due to its broad-spectrum antibacterial properties and affordable prices. Unfortunately, the high toxicity and difficult degradation rate of TC molecules make them easy to accumulate in the environment, which breaks the ecological balance and seriously threatens human health. Rapid and accurate detection of TC residue levels is important for ensuring water quality and food safety. Recently, fluorescence detection technology of TC residues has developed rapidly. Lanthanide nanomaterials, based on the high luminescence properties of lanthanide ions and the high matching with TC energy levels, are favored in the real-time trace detection of TC due to their advantages of high sensitivity, rapidity, and high selectivity. Therefore, they are considered potential substitutes for traditional detection methods. This review summarizes the synthesis strategy, TC response mechanism, removal mechanism, and applications in intelligent sensing. Finally, the development of lanthanide nanomaterials for TC fluorescence detection and removal is reasonably summarized and prospected. This review provides a reference for the establishment of a method for the accurate determination of TC content in complex food matrices. [ABSTRACT FROM AUTHOR]

Polyamines are essential analytes due to their critical role in various biological processes and human health in general. Due to their role as regulators for cell growth and proliferation (putrescine and spermine), as neuroprotectors, gero‐, and cardiovascular protectors (spermidine), and as bacterial growth indicators (cadaverine), rapid, simple, and cost‐effective methods for polyamine detection in biofluids are in demand. The present study focuses on the development and investigation of self‐assembled and fluorescent host⋅dye chemo‐sensors based on sulfonated pillar[5]arene for the specific detection of polyamines. Binding studies, as well as stability and functionality assessments of the turn‐on chemosensors for selective polyamine detection in saline and biologically relevant media, are shown. Furthermore, the practical applicability of the developed chemo‐sensors is demonstrated in biofluids such as human urine and saliva. [ABSTRACT FROM AUTHOR]

Introduction: Mycobacterium tuberculosis, the causative agent of human tuberculosis, poses a significant threat to global public health and imposes a considerable burden on the economy. However, existing laboratory diagnostic methods for M. tuberculosis are time-consuming and have limited sensitivity levels. Methods: The CRISPR/Cas system, commonly known as the "gene scissors", demonstrates remarkable specificity and efficient signal amplification capabilities. Enzymatic recombinase amplification (ERA) was utilized to rapidly amplify trace DNA fragments at a consistent temperature without relying on thermal cyclers. By integrating of CRISPR/Cas12a with ERA, we successfully developed an ERA-CRISPR/Cas12a detection system that enables rapid identification of M. tuberculosis. Results: The sensitivity of the ERA-CRISPR/Cas12a fluorescence and lateral flow systems was 9 copies/mL and 90 copies/mL, respectively. Simultaneously, the detection system exhibited no cross-reactivity with various of respiratory pathogens and non-tuberculosis mycobacteria, demonstrating a specificity of 100%. The positive concordance rate between the ERA-CRISPR/Cas12a fluorescence system and commercial qPCR was 100% in 60 clinical samples. Meanwhile, the lateral flow system showed a positive concordance rate of 93.8% when compared to commercial qPCR. Both methods demonstrated a negative concordance rate of 100%, and the test results can be obtained in 50 min at the earliest. Discussion: The ERA-CRISPR/Cas12a system offers a rapid, sensitive, and specific method that presents a novel approach to laboratory diagnosis of M. tuberculosis. [ABSTRACT FROM AUTHOR]

Two supramolecular ionic nanomaterials (SINs) were successfully prepared by multidentate imidazolium organic salts and multidentate acid via ionic self-assembly (ISA), which is formed by tetraphenylethylene (TPE)-based organic salts (TPE-COS and TPE-C16OS) and 4,4′,4″,4‴-(ethene-1,1,2,2-tetrayl)-tetrabenzenesulfonic acid (TPE-SO3H) in MeOH. These SINs exhibited high thermal stability and are insoluble in solvents. Furthermore, as fluorescence sensors, they showed high sensitivity and selectivity in the detection of nitroaromatic explosives, especially for trinitrophenol (TNP); the linear range of SIN-1 and SIN-2 was 0.4–128 μM and 1–128 μM; their λex was set as 340 and 350 nm; λem was 489 and 458 nm; and the related limit of detection was 0.87 and 0.42 μM, respectively. The quenching mechanism of TNP for SINs is the synergistic effect of the energy transfer, the inner filter, and photoelectron transfer. [ABSTRACT FROM AUTHOR]

We developed a portable multi-fluorescence detection system for loop-mediated isothermal amplification (LAMP) using an indium tin oxide (ITO) transparent glass heater by improving a previously developed device. By changing the optical design and the material of the heating part, the quantitative performance and the stability of temperature control were improved. We demonstrated the basic performance of the developed device for genetic tests using LAMP by conducting discrimination tests for human genome DNA. We also showed that quantitative analysis of human genomic DNA is possible at initial DNA concentrations of 2.11 × 10²– 2.11 × 104 ng/µL using the developed device. This genetic testing device is smaller and lighter (60 × 90 × 70 mm³, 178 g) than conventional testing devices, giving it considerable potential to facilitate rapid and efficient on-site genetic testing. [ABSTRACT FROM AUTHOR]

Isoprothiolane is a common pesticide used to manage a variety of crop diseases. It has also been linked to carcinogenic consequences in people when exposed to certain quantities for longer spans of time. As a result, the establishment of extremely sensitive and selective method to detect isoprothiolane is crucial for ecosystem protection and food safety. Recently, perovskite quantum dots (PQDs) have received rising interest as a result of their inherent fluorescence properties and applications in variety of domains. In the current study, we successfully synthesized cesium lead bromide (CsPbBr3) PQDs by using modified ligand-assisted re-precipitation method via tip sonication treatment. A strong green fluorescence of CsPbBr3 PQDs is effectively quenched after forming complex with isoprothiolane through a static quenching effect. The optical properties, morphology, chemical compositions, and diffraction patterns of CsPbBr3 PQDs were distinguished by using fluorescence, absorption, X-ray diffraction pattern, X-ray photoelectron microscopy, and high-resolution transmission electron microscopy techniques. Under the optimal reaction conditions, CsPbBr3 PQDs exhibit wide detection range (0.025-25 μM) and low detection limit (10.12 nM) for isoprothiolane detection. Furthermore, the nanoprobe has excellent selectivity for isoprothiolane, and it can be successfully applied to detect isoprothiolane in real samples. [ABSTRACT FROM AUTHOR]

Copper selenide nanoparticles (CuSeNP) were synthesized using histidine, ethylenediamine, and sodium selenate as precursors by one-step microwave digestion methods. The as-prepared CuSeNPs exhibit excellent catechol oxidase mimic enzyme and catalase (CAT)-like activities. Dopamine (DA) can be oxidized to aminochrome with H2O2 by CuSeNPs, and the intermediate product aminochrome can further react with α-naphthol to yield a highly fluorescent derivative. It was confirmed that Cr(III) could adsorb on the surface of CuSeNPs and inhibit the production of semiquinone radicals in the reaction system, and the catalytic activity of CuSeNPs was inhibited. The detection mechanisms, kinetics, and catalytic properties of CuSeNPs were systematically investigated. As a result, a novel fluorescence method for the assay of Cr(III) was established. The feasibility of CuSeNP nanozyme in detecting speciation Cr(III) in food samples was explored with satisfactory results. It showed the obvious potential for developing effective and dependable fluorescent detection method for protecting food safety. [ABSTRACT FROM AUTHOR]

Alpha-foetoprotein (AFP) is taken as a diagnostic tumor marker for the screening and diagnosis of cancer. Nucleic acid-based isothermal amplification strategies are emerging as a potential technology in early screening and clinical diagnosis of AFP. The leakages between hairpins dramatically increase the background and reduce the sensitivity. Thus, it is necessary to develop some strategies to reduce the leakage for isothermal amplification strategies. A DNAzyme-locked leakless enzyme-free amplification system was developed for AFP detection in liver cancer and breast cancer. AFP could open the apt-hairpin and initiate the catalytic hairpin assembly (CHA) reaction to produce a Y-shaped duplex. Two tails of a Y-shaped duplex cleaved the two kinds of leakless hairpins. Then, the third tail of the Y-shaped duplex catalyzed the second CHA between the cleaved leakless hairpins to recover the fluorescent intensity. The limit of detection reached 5 fg/mL by the two levels of signal amplifications. Importantly, the leakless hairpin design effectively reduced leakage between hairpins and weakened the background. In addition, it also showed a great promising potential for AFP detection in early screening and clinical diagnosis. [ABSTRACT FROM AUTHOR]

Hyperproliferative diseases are the first step for tumor formation; thymidine kinase 1 (TK1) mRNA is closely related to cell proliferation. Therefore, the risk of malignant proliferation can be identified by sensitively detecting the variance in TK1 mRNA concentration, which can be used for tumor auxiliary diagnosis and monitoring tumor treatment. Owing to the low abundance and instability of TK1 mRNA in real samples, the development of a sensitive and fast mRNA detection method is necessary. A DNA nanosensor that can be used for detecting TK1 mRNA based on bipedal 3D DNA walker–driven proximal catalytic hairpin assembly (P-CHA) was developed. P-CHA hairpins were hybridized to a linker DNA strand coupled with magnetic nanoparticles to increase their local concentrations. The bipedal DNA walking on the surface of NPs accelerates reaction kinetics using the proximity effect. Taking advantage of the signal amplification of P-CHA as well as the rapid reaction rate of the DNA walker in 80 min, the proposed sensor detects TK1 mRNA with a low detection limit of 14 pM and may then be applied to clinical diagnosis. [ABSTRACT FROM AUTHOR]

Fluorescence flow cytometry is a powerful instrument to distinguish cells or particles labelled with high-specificity fluorophores. However, traditional flow cytometry is complex, bulky, and inconvenient for users to adjust fluorescence channels. In this paper, we present a modular fluorescence flow cytometry (M-FCM) system in which fluorescence channels can be flexibly arranged. Modules for particle focusing and fluorescence detection were developed. After hydrodynamical focusing, the cells were measured in the detection modules, which were integrated with in situ illumination and fluorescence detection. The signal-to-noise ratio of the detection reached to 33.2 dB. The crosstalk among the fluorescence channels was eliminated. The M-FCM system was applied to evaluate cell viability in drug screening, agreeing well with the commercial cytometry. The modular cytometry presents several outstanding features: flexibility in setting fluorescence channels, cost efficiency, compact construction, ease of operation, and the potential to upgrade for multifunctional measurements. The modular cytometry provides a multifunctional platform for various biophysical measurements, e.g., electrical impedance and refractive-index detection. The proposed work paves an innovative avenue for the multivariate analysis of cellular characteristics. [ABSTRACT FROM AUTHOR]

One of the important problems in the environment is heavy metal pollution, and fluorescence is one of the best methods for their detection due to its sensitivity, selectivity, and relatively rapid and easy operation. In this study, 1,8-diaminonaphthalene functionalized super-stable mesoporous silica (DAN-LUS-1) was synthesized and used as a fluorescence probe to identify Hg2+ and Fe3+ in food samples. The TGA and FT-IR spectra illustrated that 1,8-diaminonaphthalene was grafted into LUS-1. XRD patterns verified that the LUS-1 and functionalized mesoporous silica have a hexagonal symmetrical array of nano-channels. SEM images showed that the rod-like morphology of LUS-1 was preserved in DAN-LUS-1. Also, surface area and pore diameter decreased from 824 m2 g⁻1 and 3.61 nm for the pure LUS-1 to 748 m2 g⁻1 and 3.43 nm for the DAN-LUS-1, as determined by N₂ adsorption–desorption isotherms. This reduction demonstrated that 1,8-diaminonaphthalene immobilized into the pore of LUS-1. The DAN-LUS-1 fluorescence properties as a chemical sensor were studied with a 340/407 nm excitation/emission wavelength that was quenched by Hg2+ and Fe3+ ions. Hg2+ and Fe3+ were quantified using the fluorescence response in the working range 8.25–13.79 × 10–6 and 3.84–10.71 × 10–6 mol/L, with detection limits of 8.5 × 10–8 M and 1.3 × 10–7 M, respectively. Hg2+ and Fe3+ were measured in vetiver grass and spinach. Since the Fe3+ quenching can move in the opposite direction with sodium hexametaphosphate (SHMP) as a hiding compound for Fe3+, consequently, the circuit logic system was established with Fe3+, Hg2+, and SHMP as inputs and the fluorescent quench as the output. [ABSTRACT FROM AUTHOR]

A new green and highly sensitive method for the determination of rhodamine B (RhB) by deep eutectic solvent-based vortex-assisted liquid–liquid microextraction with fluorescence detection (DES-VALLME-FLD) was developed. The extraction efficiency of conventional solvents and different deep eutectic solvent (DES) systems composed of tetrabutylammonium bromide (TBAB) and an alcohol (hexanol, octanol, or decanol) in different ratios were compared. DFT calculations of intermolecular electrostatic and non-covalent interactions of the most stable RhB forms with DES and water explain the experimental DESs' extraction efficiency. Semiempirical PM7 computations were used to obtain Hansen solubility parameters, which supported the good solubility of the monocationic RhB form in selected DESs. The dependence of the linear calibration of microextraction into 100 µL DES was observed in the RhB calibration range from 0.2 to 10.0 µg L−1 with a correlation coefficient of R2 = 0.9991. The LOD value was calculated to be 0.023 µg L−1. The accuracy and precision of the proposed method were verified over two days with RSD values of 2.9 to 4.1% and recovery of 94.6 to 103.7%. The developed method was applied to the determination of RhB in real samples (tap water, energy drink, and lipstick). [ABSTRACT FROM AUTHOR]

[Display omitted] • Room temperature and ultrafast synthesis of sulfur quantum dots (SQDs) is presented. • The conversion of elemental sulfur to fluorescent SQDs can be completed in 10 min. • The prepared SQDs have a photoluminescence quantum yield as high as 23.6%. • The utilization of SQDs to sensitively detect tetracycline and Ca2+ ions is reported. • A sensitive logic gate sensor based on SQDs is constructed. The direct and rapid conversion of abundant and cheap elemental sulfur into fluorescent sulfur quantum dots (SQDs) at room temperature is a critical and urgent challenge. Conventional synthesis methods require high temperatures, high pressures, or specific atmospheric conditions, making them complex and impractical for real applications. Herein, we propose a simple method for synthesizing SQDs simply by adding H 2 O 2 to an elemental sulfur-ethylenediamine (S-EDA) solution at room temperature. Remarkably, within a mere 10 min, SQDs with a photoluminescence quantum yield of 23.6 % can be obtained without the need for additional steps. A comprehensive analysis of the mechanism has demonstrated that H 2 O 2 is capable of converting S x 2− ions generated in the S-EDA solution into zero-valent sulfur atoms through oxidation. The obtained SQDs can be utilized as a fluorescent probe for detection of tetracycline (TC) and Ca2+ ions with the limit of detection (LOD) of 0.137 μM and 0.386 μM respectively. Moreover, we have developed a sensitive logic gate sensor based on SQDs, harnessing the activated cascade effect to create an intelligent probe for monitoring trace levels of TC and Ca2+ ions. This paper not only presents a viable approach for ultrafast and scalable synthesis of SQDs at room temperature, but also contributes to the efficient utilization of elemental sulfur resources. [ABSTRACT FROM AUTHOR]

A Pyrococcus furiosus Argonaute (PfAgo)-based biosensor is presented for alkaline phosphatase (ALP) activity detection in which the ALP-catalyzed hydrolysis of 3′-phosphate-modified functional DNA activates the strand displacement amplification, and the amplicon mediates the fluorescent reporter cleavage as a guide sequence of PfAgo. Under the dual amplification mode of PfAgo-catalyzed multiple-turnover cleavage activity and pre-amplification technology, the developed method was successfully applied to ALP activity determination with a detection limit (LOD) of 0.0013 U L−1 (3σ) and a detection range of 0.0025 to 1 U L−1 within 90 min. The PfAgo-based method exhibits satisfactory analytic performance in the presence of potential interferents and in complex human serum samples. The proposed method shows several advantages, such as rapid analysis, high sensitivity, low-cost, and easy operation, and has great potential in disease evolution fundamental studies and clinical diagnosis applications. [ABSTRACT FROM AUTHOR]

CRISPR/Cas system has been widely applied in the assay of disease-related nucleic acids. However, it is still challenging to use CRISPR/Cas system to detect multiple nucleic acids at the same time. Herein, we combined the preponderance of DNA logic circuit, label-free, and CRISPR/Cas technology to construct a label-free "AND" logical gate for multiple microRNAs detection with high specificity and sensitivity. With the simultaneous input of miRNA-155 and miRNA-141, the logic gate starts, and the activation chain of Cas12a is destroyed; thus, the activity is inhibited and the fluorescence of the signal probe ssDNA-AgNCs is turned on. The detection limit of this method for simultaneous quantitative detection of double target is 84 fmol/L (S/N = 3). In this "AND" logic gate, it is only necessary for the design of a simple DNA hairpin probe, which is inexpensive and easy, and since this method involves only one signal output, the data processing is very simple. What is more important, in this strategy two types of microRNAs can be monitored simultaneously by only using CRISPR/Cas12a and a type of crRNA, which offers a new design concept for the exploitation of single CRISPR/Cas system for multiple nucleic acid assays. [ABSTRACT FROM AUTHOR]

A ratiometric fluorescence sensing strategy has been developed for the determination of Cu2+ and glyphosate with high sensitivity and specificity based on OPD (o-phenylenediamine) and glutathione-stabilized gold nanoclusters (GSH-AuNCs). Water-soluble 1.75-nm size GSH-AuNCs with strong red fluorescence and maximum emission wavelength at 682 nm were synthesized using GSH as the template. OPD was oxidized by Cu2+, which produced the bright yellow fluorescence oxidation product 2,3-diaminophenazine (DAP) with a maximum fluorescence emission peak at 570 nm. When glyphosate existed in the system, the chelation between glyphosate and Cu2+ hindered the formation of DAP and reduced the fluorescence intensity of the system at the wavelength of 570 nm. Meanwhile, the fluorescence intensity at the wavelength of 682 nm remained basically stable. It exhibited a good linear relationship towards Cu2+ and glyphosate in water in the range 1.0–10 µM and 0.050–3.0 µg/mL with a detection limit of 0.547 µM and 0.0028 µg/mL, respectively. The method was also used for the semi-quantitative determination of Cu2+ and glyphosate in water by fluorescence color changes visually detected by the naked eyes in the range 1.0–10 µM and 0.30–3.0 µg/mL, respectively. The sensing strategy showed higher sensitivity, more obvious color changes, and better disturbance performance, satisfying with the detection demands of Cu2+ and glyphosate in environmental water samples. The study provides a reliable detection strategy in the environment safety fields. [ABSTRACT FROM AUTHOR]

The combination of CRISPR/Cas12a and functional DNA provides the possibility of constructing biosensors for detecting non-nucleic-acid targets. In the current study, the duplex protospacer adjacent motif (PAM) in the activator of CRISPR/Cas12a was used as a molecular switch, and a sensitive adenosine triphosphate (ATP) detection biosensor was constructed using an allosteric probe-conjugated PAM site formation in hybridization chain reaction (HCR) integrated with the CRISPR/Cas12a system (APF-CRISPR). In the absence of ATP, an aptamer-containing probe (AP) is in a stem-loop structure, which blocks the initiation of HCR. In the presence of ATP, the structure of AP is changed upon ATP binding, resulting in the release of the HCR trigger strand and the production of long duplex DNA with many PAM sites. Since the presence of a duplex PAM site is crucial for triggering the cleavage activity of CRISPR/Cas12a, the ATP-dependent formation of the PAM site in HCR products can initiate the FQ-reporter cleavage, allowing ATP quantification by measuring the fluorescent signals. By optimizing the sequence elements and detection conditions, the aptasensor demonstrated superior detection performance. The limit of detection (LOD) of the assay was estimated to be 1.16 nM, where the standard deviation of the blank was calculated based on six repeated measurements. The dynamic range of the detection was 25–750 nM, and the whole workflow of the assay was approximately 60 min. In addition, the reliability and practicability of the aptasensor were validated by comparing it with a commercially available chemiluminescence kit for ATP detection in serum. Due to its high sensitivity, specificity, and reliable performance, the APF-CRISPR holds great potential in bioanalytical studies for ATP detection. In addition, we have provided a proof-of-principle for constructing a CRISPR/Cas12a-based aptasensor, in which the PAM is utilized to regulate Cas12a cleavage activity. [ABSTRACT FROM AUTHOR]

The combination of silica nanoparticles with fluorescent molecularly imprinted polymers (Si-FMIPs) prepared by a one-pot sol-gel synthesis method to act as chemical sensors for the selective and sensitive determination of captopril is described. Several analytical parameters were optimized, including reagent ratio, solvent, concentration of Si-FMIP solutions, and contact time. Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and the ninhydrin assay were used for characterization. The selectivity was evaluated against molecules belonging to other drug classes, such as fluoroquinolones, nonacid nonopioids, benzothiadiazine, alpha amino acids, and nitroimidazoles. Under optimized conditions, the Si-FMIP-based sensor exhibited a working range of 1–15 µM, with a limit of detection (LOD) of 0.7 µM, repeatability of 6.4% (n = 10), and suitable recovery values at three concentration levels (98.5% (1.5 µM), 99.9% (3.5 µM), and 99.2% (7.5 µM)) for wastewater samples. The sensor provided a working range of 0.5–15 µM for synthetic urine samples, with an LOD of 0.4 µM and a repeatability of 7.4% (n = 10) and recovery values of 93.7%, 92.9%, and 98.0% for 1.0 µM, 3.5 µM, and 10 µM, respectively. In conclusion, our single-vessel synthesis approach for Si-FMIPs proved to be highly effective for the selective determination of captopril in wastewater and synthetic urine samples. [ABSTRACT FROM AUTHOR]

ObjectiveTo achieve high throughput and high detection rate of circulating tumor cells (CTCs) in human peripheral blood, and to provide efficient and accurate early screening for cancer patients. MethodsA microfluidic chip with the integration of sorting, enrichment and detection was designed, and CTCs at the single cell level were detected by fluorescence detection system to obtain the number of CTCs in samples. ResultsThe peripheral blood samples after lysed red blood cells were used for 6 experiments. When the injection rate reached 0.2 mL/h, CTCs could reach the best detection rate of 78.6%, and the correlation coefficient within the group was above 0.8. ConclusionCTCs detection system can achieve high detection rate and has good reliability, which can provide a reliable reference for clinical research in related fields.

The pursuit of compact and integrated devices has stimulated a growing demand for multifunctional sensors with rapid and accurate responses to various physical parameters, either separately or simultaneously. Fluorescent fiber sensors have the advantages of robust stability, light weight, and compact geometry, enabling real-time and noninvasive signal detection by monitoring the fluorescence parameters. Despite substantial progress in fluorescence sensors, achieving multifunctional sensing in a single optical fiber remains challenging. To solve this problem, in this study, we present a bottom-up strategy to design and fabricate thermally drawn multifunctional fiber sensors by incorporating functional nanocrystals with temperature and pressure fluorescence responses into a transparent glass matrix. To generate the desired nanocrystal-in-glass composite (NGC) fiber, the fluorescent activators, incorporated nanocrystals, glassy core materials, and cladding matrix are rationally designed. Utilizing the fluorescence intensity ratio technique, a self-calibrated fiber sensor is demonstrated, with a bi-functional response to temperature and pressure. For temperature sensing, the NGC fiber exhibits temperature-dependent near-infrared emission at temperatures up to 573 K with a maximum absolute sensitivity of 0.019 K−1. A pressure-dependent upconversion emission is also realized in the visible spectral region, with a linear slope of -0.065. The successful demonstration of multifunctional NGC fiber sensors provides an efficient pathway for new paradigms of multifunctional sensors as well as a versatile strategy for future hybrid fibers with novel combinations of magnetic, optical, and mechanical properties.

Daptomycin (DPT) is a lipopeptide antibiotic used primarily to treat severe infections caused by Gram-positive bacteria. A spectrofluorimetric detection of DPT using metal oxide nanosensors synthesized via Commiphora myrrha extract in the presence of an organizing solution is presented in this study. The study describes a unique analytical method for detecting daptomycin (DPT) in pharmaceutical formulations, which employs a novel fluorescent system based on zinc oxide nanoparticles (ZnO-NPs) and cetylpyridinium chloride (CPC). The ZnO-NPs were produced using an environmentally friendly technique that included Commiphora myrrha extract, which serves as both a reducing and stabilizing agent in the green synthesis process. The morphology, size, and structural properties of the ZnO-NPs were carefully investigated utilizing a variety of spectroscopic and microscopic methods. The new method makes use of the unique fluorescence capabilities of ZnO-NPs in the presence of CPC for the highly sensitive and selective detection of DPT. This method facilitates precise quantification over a wide calibration range of 0.05–10 µg/mL, exhibiting remarkable sensitivity. The method is highly accurate, with DPT recoveries typically surpassing 99 %, indicating its reliability. Intermediate precision was utilized to evaluate both accuracy and precision in accordance with methodological requirements. The greenness of the method assessment emphasizes its ecologically friendly approach, which uses Commiphora myrrha extract for the sustainable synthesis of ZnO-NPs, minimizing environmental effects while maintaining strong analytical performance.

Escherichia coli O157:H7 (E. coli O157:H7) is a foodborne pathogenic microorganism that is commonly found in the environment and poses a significant threat to human health, public safety, and economic stability worldwide. Thus, early detection is essential for E. coli O157:H7 control. In recent years, a series of E. coli O157:H7 detection methods have been developed, but the sensitivity and portability of the methods still need improvement. Therefore, in this study, a rapid and efficient testing platform based on the CRISPR/Cas12a cleavage reaction was constructed. Through the integration of recombinant polymerase amplification and lateral flow chromatography, we established a dual-interpretation-mode detection platform based on CRISPR/Cas12a-derived fluorescence and lateral flow chromatography for the detection of E. coli O157:H7. For the fluorescence detection method, the limits of detection (LODs) of genomic DNA and E. coli O157:H7 were 1.8 fg/µL and 2.4 CFU/mL, respectively, within 40 min. Conversely, for the lateral flow detection method, LODs of 1.8 fg/µL and 2.4 × 102 CFU/mL were achieved for genomic DNA and E. coli O157:H7, respectively, within 45 min. This detection strategy offered higher sensitivity and lower equipment requirements than industry standards. In conclusion, the established platform showed excellent specificity and strong universality. Modifying the target gene and its primers can broaden the platform's applicability to detect various other foodborne pathogens. [ABSTRACT FROM AUTHOR]

Staining of foods by toxic mycotoxins is a general severe problem in the world. To explore simple methods for effective monitoring of mycotoxin-stained foods has extraordinary significance. Herein, we designed and prepared a covalent organic framework (COF)-derived fluorescent composite (DhBd-PT-COF-FITC) by anchoring a continually utilized fluorescent tag, fluorescein isothiocyanate (FITC), in the nanopore channel of a two-dimensional imine COF (DhBd-PT-COF) to detect a major existent mycotoxin of moldy sugar cane3-nitropropionic acid (3-NPA), which is closely related to toxicosis events of humans. Tying FITC molecules into the pore channels of DhBd-PT-COF can not only enhance the fluorescence intensity of FITC by relying on the confinement effect of DhBd-PT-COF but also retain inherent pH-responsive characteristics. As a result, DhBd-PT-COF-FITC showed the selective and sensitive response to 3-NPA. The detection limit of DhBd-PT-COF-FITC toward 3-NPA is achieved to be ultralow as 12.5 nM. More attractively, facile recovery of DhBd-PT-COF-FITC can be obtained via simple alkaline treatment. The prepared sensor has also been used to detect 3-NPA in actual sugar cane samples with satisfying recovery. Our work not only exhibits fascinating performance of COF-derived fluorescent composites toward 3-NPA monitoring but also offers a prospective approach to develop various specific materials for other targets. [ABSTRACT FROM AUTHOR]

Low-density lipoprotein cholesterol (LDL-C), commonly called "bad cholesterol", is crucial to cardiovascular health. Increased LDL-C levels pose a substantial risk to human health. As a result, there is a demand for reliable, affordable, and highly sensitive analytical methods for LDL-C detection. Herein, a facile fluorometric aptasensor for LDL-C detection based on the aptamer-enhanced peroxidase-mimicking activity of gold nanoparticles (AuNPs) has been developed. AuNPs were functionalized with LDL-C-specific thiolated aptamer to enhance their intrinsic peroxidase-like activity, which could effectively catalyze the oxidation of o-phenylenediamine dihydrochloride (OPD) by H2O2 into the yellow-fluorescent product 2,3-diamino phenazine (DAP). The characterization studies confirmed that the presence of the aptamer enhances the affinity of AuNPs toward the OPD substrate, thereby leading to a marked increase in the peroxidase-mimicking activity. Moreover, after being functionalized with an aptamer, increased dispersibility and substrate affinity of AuNPs were achieved. Using LDL-C as a target analyte, under optimum conditions, a linear relationship between smartphone-recorded signal intensity and the logarithm of the analyte concentration was observed in the range of 0.05–1 mg dL–1 and the limit of detection was 0.0230 mg dL–1. The results agree with those obtained by a clinical laboratory method. This proposed method is readily deployable and a promising prototype for diverse diagnostic applications, particularly in biomarker detection within serum or plasma samples. It holds the potential to yield substantial advantages in point-of-care testing. [ABSTRACT FROM AUTHOR]

A target-triggered strand displacement-assisted target recycling based on carbon dots-based fluorescent probe and mesoporous silica nanoparticles@polydopamine (MSNs@PDA) was established to detect miRNA. The surface of MSNs rich in mesopores was coated with a layer of PDA, which can adsorb and quench the fluorescence of single-stranded Fuel DNA with fluorescent carbon dots (CDs) modified at the end through fluorescence resonance energy transfer (FRET). After adding double-stranded DNA-gold nanoparticles (dsDNA-AuNPs) and target let-7a, it will trigger two toehold-mediated strand displacement reactions (TSDR), leading to the recovery of fluorescence and the recycling of target let-7a (excitation wavelength: 380 nm; emission wavelength: 458 nm). The recovery value of fluorescence is proportional to the logarithm of the target microRNA let-7a concentration, thus realizing the sensitivity amplification detection of disease markers. The MSNs@PDA@Fuel DNA-CDs/dsDNA-AuNPs nanoplatform based on the strategy of "on–off–on" and TSDR cyclic amplification may hold great potential as an effective and safe nanoprobe for accurate fluorescence imaging of diseases related to miRNA with low abundances. [ABSTRACT FROM AUTHOR]

The increased use of metallic nanoparticles has led to concern for environmental contamination and disruption in water quality. Therefore, effective screening of metallic nanoparticles is important for detecting metallic nanoparticles in aquatic environments. Biosensors offer several advantages, including high sensitivity to pollutants, short response time, energy efficiency, and low waste generation. In this study, a whole-cell biosensor was developed using microalga Chlorella vulgaris as a recognition element, and its fluorescence response was used as a measuring parameter for detecting the presence of titanium dioxide (TiO2) and silver (Ag) nanoparticles in water. The responses of C. vulgaris at the lag, exponential, and stationary phases to different concentrations of TiO2 and Ag nanoparticles were studied. The results showed that in TiO2 and Ag nanoparticles exposures, the highest fluorescence change (50-150%) was observed at the lag phase, whereas the lowest fluorescence change (40-75%) was observed at the stationary phase. A significant fluorescence change was observed in 15 min. The immobilized C. vulgaris under TiO2 and Ag nanoparticles exposures showed 30-180% higher fluorescence change than the negative control, indicating the potential of C. vulgaris as a biosensor for rapid detection of TiO2 and Ag nanoparticles in water. The mathematical modeling of the responses of C. vulgaris to TiO2 and Ag nanoparticles at 15 min of exposure with high R² indicated that this biosensor is sensitive to the concentration tested (0.010-10.000 mg.L-1). Taken together, these results reveal that, for the first time, it is possible to detect TiO2 and Ag nanoparticles in water within a very short time using a microalgae-based biosensor. Moreover, no genetic engineering requirement makes this biosensor simple, economical, and free from the restriction on genetically modified microorganisms for environmental applications. [ABSTRACT FROM AUTHOR]