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Herein, the serendipitous discovery of two water-recyclable and reusable fluorescent sensors IMPC (cyan–blue–cyan) and IMPC-OH (green–blue–green) is reported for sensing nerve agent simulants diethylcyanophosphonate and diethylchlorophosphate, respectively, with high sensitivity, short response time, and low detection limits. The unique features of these probes are their regeneration with the addition of a green and cheap solvent, namely water in CHCl₃, and ease of fabrication into a portable paper-strip system that can also be regenerated. Various spectroscopic studies were employed to understand the mechanism of sensing and regeneration of both probes; the results reveal that water plays a critical role in the hydrolysis of the adduct formed with DCNP and DCP, which enables the retrieval of the probe with its original fluorescence.

Electrochemical detection methods hold many advantages over their optical counterparts, such as operation in complex sample matrices, low-cost and high volume manufacture and possible equipment miniaturisation. Despite these advantages, the use of electrochemical detection is currently limited in the clinical setting. There is a wide range of potential electrode materials, selected for optimal signal-to-noise ratios and reproducibility when detecting target analytes. The use of carbon paste electrodes (CPEs) for electrochemical detection can be limited by their analytical performance, however they remain very attractive due to their low cost and biocompatibility. This paper presents the fabrication of an easy-to-make and use graphite powder/paraffin wax paste combined with a substrate produced via additive manufacturing and confirms its functionality for both direct and indirect electrochemical measurements. The produced CPEs enable the direct voltammetric detection of hexaammineruthenium(III) chloride and dopamine at an experimental limit of detection (ELoD) of 62.5 μM. The key inflammatory biomarker Interleukin-6 through an enzyme-linked immunosorbant assay (ELISA) was also quantified, yielding a clinically-relevant ELoD of 150 pg ml⁻¹ in 10% human serum. The performance of low-cost and easy-to-use CPEs obtained in 0.5 hours is showcased in this study, demonstrating the platform's potential uses for point-of-need electroanalytical applications.

Lung cancer is one of the most commonly occurring malignant tumours worldwide. Although some reference methods such as X-ray, computed tomography or bronchoscope are widely used for clinical diagnosis of lung cancer, there is still a need to develop new methods for early detection of lung cancer. Especially needed are approaches that might be non-invasive and fast with high analytical precision and statistically reliable. Herein, we developed a swab “dip” test in saliva whereby swabs were analysed using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy harnessed to principal component analysis–quadratic discriminant analysis (QDA) and variable selection techniques employing successive projections algorithm (SPA) and genetic algorithm (GA) for feature selection/extraction combined with QDA. A total of 1944 saliva samples (56 designated as lung-cancer positive and 1888 designed as controls) were obtained in a lung cancer-screening programme being undertaken in North-West England. GA-QDA models achieved, for the test set, sensitivity and specificity values of 100.0% and 99.1%, respectively. Three wavenumbers (1422 cm⁻¹, 1546 cm⁻¹ and 1578 cm⁻¹) were identified using the GA-QDA model to distinguish between lung cancer and controls, including ring C–C stretching, CN adenine, Amide II [δ(NH), ν(CN)] and ν_s(COO⁻) (polysaccharides, pectin). These findings highlight the potential of using biospectroscopy associated with multivariate classification algorithms to discriminate between benign saliva samples and those with underlying lung cancer.

Nanozymes, serving as synthetic alternatives to natural enzymes, offer several benefits including cost-effectiveness, enzyme-like catalytic abilities, enhanced stability, adjustable catalytic activity, easy recyclability, mild reaction conditions, and environmental friendliness. Nonetheless, the ongoing quest to develop nanozymes with enhanced activity and to delve into the catalytic mechanism remains a challenge. In our research, we effectively developed Au@CuO nanocomposites (Au@CuO Nc), replicating the functions of four enzymes found in nature: peroxidase (POD), catalase (CAT), glutathione peroxidase (GPx), and oxidase (OXD). The catalytic efficiency of Au@CuO Nc for TMB oxidation (oxTMB) was approximately 4.8 times greater than that of plain Cu₂O cubes, attributed to the synergistic catalytic impact between the Au element and Cu₂O within Au@CuO Nc. Mechanistic studies revealed that the novel Au@CuO Nc nanozyme greatly enhances the decomposition of H₂O₂ to reactive oxygen species (ROS) intermediates (˙OH, ˙O₂⁻ and ¹O₂), resulting in increased POD-like activity of the single-component Cu₂O cubes. When an antioxidant like TA was added to the chromogenic system, it converted oxTMB into a colorless form of TMB, enabling further evaluation of TA. Hence, a colorimetric sensor was developed for the rapid and precise quantitative measurement of TA, demonstrating strong linearity between 0.3 and 2.4 μM and featuring a low detection threshold of 0.25 μM. Moreover, this sensor was effectively utilized for the assessment of TA in actual tea samples. This work innovatively proposes a simplified and reliable strategy for the advanced design of highly effective Cu-based nanozymes, enhancing enzyme-like reactions for simultaneous, on-site colorimetric probing of antioxidants.

Strategies based on nanomaterials for sterilization address the problem of antibiotic resistance faced by conventional antimicrobials, with the contribution of photocatalytic compounds being particularly prominent. Herein, to integrate multiple bactericidal techniques into a system for generating synergistic antibacterial effects, a novel photo-triggered AuAg@g-C₃N₄ composite nanoplatform was constructed by anchoring AuAg on the surface of a g-C₃N₄ layer. As the composite nanoplatform had a lower bandgap and superior visible light utilization efficiency, it could facilitate free electron transfer better and exhibit superior photocatalytic activity under light conditions. Moreover, the AuAg@g-C₃N₄ composite nanoplatform integrated the bactericidal modes of silver ion toxicity, physical disruption of bacterial cell membranes by the multilayer structure, and excellent photocatalytic activity, exhibiting extremely superior bactericidal effects against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis, with a bactericidal efficiency of up to 100%.

While it is recognized that early diagnosis of cancer-related biomarkers can become an effective avenue for timely treatment and successfully improve patient survival, it remains challenging to get accurate inspection results. Currently, most reported cancer biomarker sensing methods are focused on the quantitative detection of a single type of biomarker, which makes accurate medical diagnostics difficult. In this work, we constructed a DNA walker nanomachine aptasensor based on gold nanoparticles for the simultaneous sensing of dual cancer biomarkers. The aptamers, labelled with a fluorophore, hybridized with complementary strands on the gold nanoparticle surface, serve as a walking track. Target analytes bind to their specific aptamers, leading to the dissociation of the unstable double-strand spherical nucleic acid. Exonuclease I (Exo I) selectively digested the aptamers bound with the target analytes, then the released targets go back to the next apamers on the gold nanopareticles surface for walking. The use of spherical nucleic acid probes improved the sensitivity of analyte detection. Exo I provided a driving power for target recycling and considerably improved the sensitivity of the aptasensor as well. The DNA walker nanomachine aptasensor was successfully applied for the detection of carcinoembryonic antigen (CEA) in the range of 0.167 to 3.34 ng mL⁻¹, and mucin-1 (MUC-1) in the same range. Moreover, we used the two aptamers to construct the DNA walker nanomachine and achieved the simultaneous detection of CEA and MUC-1, thus having great potential for biomolecular logic gate construction and early disease diagnosis.

Baijiu, a traditional Chinese alcoholic beverage, carries China's rich historical and cultural heritage. Consumers experience varying levels of relaxation and pleasure after consuming different types of Baijiu, with the biological basis of delectation influenced by serotonin and dopamine. In this study, we prepared carbon fiber electrodes modified with surface decorated gold nanoparticles to directly measure the electrochemical response signals in the serum of mice before and after gavage with different types of Baijiu. It was observed that the serum signal change in mice after consuming Baijiu sample 1 (J1) was higher than that of the other two types of Baijiu. Consequently, trace flavor compounds in the Baijiu samples were detected using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), revealing the highest content of L-lactic acid in J1. Mice were intraperitoneally injected with 200 mg kg⁻¹ of L-lactic acid. The changes in dopamine and serotonin in the serum of the injected mice were monitored using a biosensor, and the results were compared with the results of high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-MS). The findings confirmed that L-lactic acid could indeed stimulate the secretion of both neurotransmitters in mice, suggesting that the trace components in J1 may even exhibit synergistic effects. This study contributes to a deeper understanding of the effects of Baijiu on the body and provides a scientific basis for the production and consumption of Baijiu.

Human serum albumin (HSA) is a multifunctional circulatory protein essential for many physiological processes including oncotic pressure maintenance, ligand/drug binding and transport, antioxidant activity, etc. Abnormal HSA levels in biological fluids have been reported in a variety of clinical disorders, making it a potential biomarker for early diagnosis. Low serum albumin levels have been linked to increased long- and short-term mortality rates in ICU patients. Therefore, quantifying HSA in biofluids such as serum and urine offers a convenient approach for the early identification of underlying clinical conditions and assessing the risk factors. Herein, we report a series of fluorescent 1,4-dihydropyridine (DHP) derivatives for the detection and quantification of HSA in biofluids. Their response towards HSA can be tuned by varying the substituents at the C-4 and the N-1 of the DHP ring. Depending on the nature of the substituents, they generated either a turn-on or ratiometric response with a LoD in low nanomolar or subnanomolar levels. A pair of enantiomers obtained by introducing a chiral center on the N-substituents highlighted the importance of stereochemistry in HSA-ligand interactions. Quantification of HSA in complex biofluids, such as blood serum and urine, was also accomplished using these probes. The high selectivity of some of the probes towards HSA over the homologous BSA allowed the discrimination of these two proteins. The preferred binding location of the probes was the hemin binding site and the detection mechanism was identified as the restriction of intramolecular rotation. Additionally, a prototype of a smartphone-integrated point-of-care device was also fabricated to demonstrate the feasibility of utilizing these probes in clinical settings.

Although CRISPR-based nucleic acid detection has great potential in point-of-care testing due to its simplicity, it has been rarely integrated into paper-based analytical devices (PADs), which are attractive platforms to simplify assays. This work introduces a CRISPR-assisted nucleic acid quantification approach integrated into a PAD with signal readout by a personal glucose meter (PGM). Retention of magnetic beads by filter paper and pre-deposition of all required reagents by freeze-drying stabilized with trehalose enabled the indirect quantification of human papilloma virus (HPV) DNA through a PGM readout without complicated user intervention and complex reagent handling. The calculated limit of detection was 57 pM, which is comparable with other amplification-free CRISPR-based assays detecting nucleic acids. The fully integrated device exhibited good storage stability for up to 4 weeks, suggesting its applicability toward practical point-of-care nucleic acid quantification.