·ATP-enhanced PB@MIL-100(Fe) nanozyme enables dual-mode ratiometric colorimetric and smartphone-based hydrogel detection of nitrite in food samples.

Adenosine triphosphate (ATP) is produced mainly in the mitochondrion, and its primary task is to function as a ubiquitous energy currency to meet the cellular metabolic demands in biological system...

A derivative of 3,3′,5,5′-tetramethylbenzidine for highly robust colorimetric sensing of nitrite in food samples

A novel colourimetric method for the detection of nitrite in food samples using digital image colourimetry (DIC) by smartphone is developed. Nitrite directly oxidise 3,3′,5,5′‐tetramethylbenzidine (TMB) to form a yellow TMB diimine (oxTMB). A smartphone was used to capture the image of an inherent colour variation and analyse the image with the RGB (red, green, and blue) model, achieving the quantitative detection of nitrite. Linear response for the detection of nitrite was obtained from 10 μmol L −1 to 440 μmol L −1 and the limit of quantification was 2.34 μmol L −1 . The applicability of the method was confirmed by the detection of nitrite in cabbage, pickle, and ham. The recovery was varied in the range from 96.2 % to 108.2 % with a relative standard deviation of less than 5.0 %. The simple, sensitive, and inexpensive method was an alternative for the detection of nitrite in food samples.

Enzyme-mimetic properties of nanomaterials can be efficiently tuned by controlling their size, composition, and structure. Here, ultrathin PdCu alloy nanosheet-assembled three-dimensional (3D) nanoflowers (Pd1Cux NAFs) with tunable surface composition are obtained via a generalized strategy. In presence of H2O2, the as-synthesized Pd1Cux NAFs can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to the oxidized form of TMB (oxTMB) with a characteristic absorption peak at 652 nm. Interestingly, Pd1Cux NAFs show obviously composition-dependent peroxidase-like catalytic activities because of the synergistic interaction of nanoalloy. Additionally, different from 2D Pd nanosheets, the distinctive 3D superstructures are featured with rich approachable sites and proper layer spacing, which are in favor of fast mass transport and electron transfers during the catalytic process. Among the studied Pd1Cux NAFs, the Pd1Cu1.7 NAFs show the highest enzyme-like activities and can be successfully applied for the colorimetric detection of glucose with a low detection limit of 2.93 ± 0.53μM. This work provides an efficient avenue to fabricate PdCu NAF nanozymes in biosensing toward glucose detection. Two-dimensional (2D) PdCu ultrathin nanosheet-assembled 3D nanoflowers (Pd1Cux NAFs) with tunable surface composition exhibit substantially enhanced intrinsic peroxidase-like catalytic activities. The Pd1Cu1.7 NAFs are successfully used as peroxidase mimic catalyst for the colorimetric detection of glucose with low detection limit of 2.93μM.

Ionic liquid-modified COF nanosphere for efficient extraction and sensitive detection of bisphenol pollutants.

Rapid and sensitive detection of foodborne pathogens is essential for ensuring food safety and protecting public health. In this study, we developed an innovative microfluidic fluorescence digital analysis platform enhanced by deep learning to detect pathogens at ultra-low concentrations. The biosensor features a staggered herringbone double-spiral (SHDS) microfluidic design, seamlessly integrating bacteria capture, detection, and release processes using Quantum dot (QD)-Aptamer conjugates for precise identification. Fluorescence image analysis, powered by a Resnet-18-based convolutional neural networks (CNN), directly quantifies Escherichia coli (E. coli) concentrations from fluorescence images, streamlining data processing and increasing sensitivity. The platform offers a linear detection range from 10 to 3 × 10⁶ CFU/mL (R² = 0.990), achieves capture efficiencies of up to 100 % at low bacterial concentrations (4 × 10² CFU/mL), and offers an ultra-low detection limit of 2 CFU/mL within just 1.5 hours. The CNN model effectively filters out background noise and interferences, achieving over 99 % predictive accuracy. Validation using milk and chicken samples resulted in high recovery rates (96.7 % to 104.0 %). This biosensor presents a rapid, reliable, and practical solution for pathogen detection in complex food matrices, significantly improving food safety and security. • Developed a novel microfluidic biosensor integrating E. coli enrichment, detection, and release. • Achieved up to 100 % E. coli capture efficiency at 4 × 10² CFU/mL using asymmetric herringbone structures and Con A-modified channels. • Enhanced fluorescence analysis with deep learning , achieving a detection limit of 2 CFU/mL. • Demonstrated high predictive accuracy (>99 %) and recovery rates (96.7 % to 104.0 %) in food samples. • Applied a CNN model to eliminate background noise, enabling precise detection in complex food matrices.

In this work, a novel and very interesting analytical methodology based on coupling of digital image processing and three-way calibration has been developed for determination of nitrite in food samples. Nitrite in contact with Griess reagent is able to produce a red-colored azo dye whose color intensity is correlated with nitrite concentration and here, a piece of Whatman filter paper impregnated with Griess reagent was used as the platform of the sensor and a SONY Xperia Z5 cell phone was used for image capturing from the sensor surface. To generate second-order data, the F-number of the camera's sensor was changed as an instrumental parameter. Two calibration models were constructed by unfolded partial least squares-residual bilinearization (U-PLS/RBL) and multiway-PLS/RBL (N-PLS/RBL) and then, their performance for prediction of nitrite concentration in test samples was evaluated and the results confirmed a good performance for U-PLS/RBL (REP = 3.25 ppm, RMSEP = 8.82 ppm, RMSEC = 4.62 ppm, Q2 = 0.99, γ−1 = 0.05 and LOD = 0.1 ppm) which was better than that for N-PLS/RBL (REP = 13.98 ppm, RMSEP = 37.86 ppm, RMSEC = 6.46 ppm, Q2 = 0.98, γ−1 = 0.07 and LOD = 0.15 ppm) in predicting concentration of nitrite in test samples which motivated us to choose it for the analysis of cabbage, carrot, lettuce, watermelon, onion, potato, kielbasa and sausage as real samples.

Quantitative detection of cancer cells using portable devices is promising for the development of simple, fast, and point-of-care cancer diagnostic techniques. However, how to further amplify the detection signal to improve the sensitivity and accuracy of detecting cancer cells by portable devices remains a challenge. To solve the problem, we, for the first time, synthesized folic-acid-conjugated Au nanoframes (FA-Au NFs) with amplification of pressure and temperature signals for highly sensitive and accurate detection of cancer cells by portable pressure meters and thermometers. The resulting Au NFs exhibit excellent near-infrared (NIR) photothermal performance and catalase activity, which can promote the decomposition of NH4HCO3 and H2O2 to generate corresponding gases (CO2, NH3, and O2), thereby synergistically amplifying pressure signals in a closed reaction vessel. At the same time, Au NFs with excellent peroxidase-like activity can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce TMB oxide (oxTMB) with a strong photothermal effect, thereby cooperating with Au NFs to amplify the photothermal signal. In the presence of cancer cells with overexpressing folate receptors (FRs), the molecular recognition signals between FA and FR can be converted into amplified pressure and temperature signals, which can be easily read by portable pressure meters and thermometers, respectively. The detection limits for cancer cells using pressure meters and thermometers are 6 and 5 cells/mL, respectively, which are better than other reported methods. Moreover, such Au NFs can improve tumor hypoxia by catalyzing the decomposition of H2O2 to produce O2 and perform photothermal therapy of cancer. Together, our work provides new insight into the application of Au NFs to develop a dual-signal sensing platform with amplification of pressure and temperature signals for portable and ultrasensitive detection of cancer cells as well as personalized cancer therapy.

An effective signal amplification strategy based on temperature-amplification synergistic pressure was designed for the sensitive detection of carcinoembryonic antigen (CEA) by using a noncontact point-of-care testing (POCT) aptasensor with a flexible pressure sensor based on a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-modified sponge (PEDOT:PSS-sponge). In the biological recognition system, target analyte triggered the release of platinum nanoparticle-labeled complementary DNA (Pt-cDNA) from CEA aptamer-conjugated magnetic beads. On the basis of the unique characteristics of platinum nanoparticles (e.g., catalytic ability for H2O2 decomposition, peroxidase-like catalytic activity, and photothermal characteristics), the platinum nanoparticles (PtNPs) could not only catalyze hydrogen peroxide (H2O2) to produce a large amount of oxygen (O2) but could also assist the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to a photothermal agent ox-TMB with the increasing temperature. Under 808 nm near-infrared (NIR) laser irradiation, an increase in the pressure and temperature occurred simultaneously in the closed detection cell. Meanwhile, the increasing temperature could be helpful for further increasing the pressure. The flexible pressure sensor was compressed in a closed system to cause a decrease in contact resistance, thereby establishing a correlation between the concentration and the resistance-readable analysis. Under optimum conditions, the dynamic detection range of this detection strategy for target CEA was between 0.2 and 80 ng mL-1, and the limit of detection (LOD) was 0.15 ng mL-1. Overall, the signal amplification strategy of temperature coordination provides possibilities for the future development of sensitive and portable POCT protocols.

Photosensitization, originated from the activation of triplet states, is the basis of many photodynamic applications, but often competes with a series of nonradiative processes. Herein, we communic...

Portable foodborne pathogen detection via ratiometric fluorescence nanoprobe for adenosine triphosphate quantification based on DNA-functionalized metal-organic framework.

As a common food additive, nitrites are used in processed meat products, primarily for color enhancement and preservation. Excessive intake of nitrites can lead to high toxicity to pose a significant risk to human health, including potential carcinogenicity and even death. Consequently, developing a rapid and sensitive method for nitrite detection is crucial for food safety monitoring. Herein, this study is developing a nitrite detection system utilizing blue‐fluorescent carbon dots (CDs) derived from carboxylate cellulose. This system operates by detecting the quenching of CDs fluorescence, which is caused by Fe3⁺ ions generated via the oxidation of Fe2⁺ by nitrite under acidic conditions. Within a concentration range of 1–1000 µm, the system demonstrates a strong linear relationship between CDs fluorescence intensity and nitrite concentration, with a detection limit of 0.42 µm. Furthermore, this study is designing a novel CDs‐based fluorescent test strip for rapid and visual nitrite quantification in pakchoi cabbage samples, enabling detection within 30 min. Overall, the CDs‐based fluorescent test strips hold great promise for enhancing food safety monitoring, ensuring effective nitrite control, and protecting public health from the potential risks associated with excessive nitrite consumption.

Smartphone-based colorimetric determination of glucose in food samples based on the intrinsic peroxidase-like activity of nitrogen-doped carbon dots obtained from locusts

Construction of a bioinspired Fe3O4/N-HCS nanozyme for highly sensitive detection of GSH

Chitosan-based antibacterial AIE luminogens for bioimaging and dual-mode detecting of nitrite in food samples.