Tyrosinase is a key biomarker in melanoma, emphasizing the need for reliable detection. Here, we developed a ratiometric fluorescent probe that undergoes enzyme-triggered structural transformation, evidenced by HPLC and spectral changes. It enables sensitive analysis, inhibitor evaluation, and detection in spiked human serum, demonstrating potential for diagnostic applications.
Hypochlorous acid (HOCl), a key reactive oxygen species, is generated in vivo through the catalytic action of myeloperoxidase and plays a crucial role in innate immunity. However, dysregulation of HOCl levels can contribute to the development of various diseases. Due to its high reactivity, short lifespan, and limited diffusion distance in biological systems, real-time tracking of HOCl presents significant challenges. In this study, we have successfully designed and synthesized a novel fluorescent “turn-on” probe, BZDC, based on benzothiazole derivatives. The probe exhibits exceptional sensitivity for detecting OCl−, with a detection limit as low as 0.953 µM, and demonstrates excellent selectivity. A distinct color change from colorless to light yellow is observed in the solution during detection. The response mechanism of BZDC to OCl− was elucidated through various experimental techniques, including UV-Vis absorption spectroscopy, fluorescence titration, NMR titration, and mass spectrometry. Furthermore, BZDC exhibits low cytotoxicity and has been successfully applied to image OCl− in living cells. These findings provide valuable insights for the future development of hypochlorite sensors for a range of chemical and biological applications.
Nanosensors have become a revolutionary tool, enabling early diagnosis and continuous monitoring of diseases with high accuracy. These tiny devices, operating at the nanoscale (typically between 1 and 100 nm), serve as signal generators to detect minute changes that traditional diagnostic tools might miss. The combination of nanoscale precision and their multifunctional capabilities shows a substantial advancement in nanotechnology and its practical applications. Nanotechnology is increasingly used across various fields, including healthcare, environmental monitoring, and manufacturing. However, significant challenges persist in the design and fabrication of nanosensors, particularly in achieving high precision, sensitivity, and selectivity, as well as in managing the inherent complexities of operation at atomic and molecular scales. To address these challenges, this paper explores various fabrication techniques, advances in material development, and strategies to enhance sensor feedback and responsiveness through a comprehensive knowledge system, known as the function-context-behavior-principle-state-structure (FCBPSS) framework. This framework is employed to categorize information and insights related to nanosensor development for early disease detection. One contribution of this paper is to critically examine the functions and principles that drive the development of nanosensors in biomedical systems, as well as their behavior and structural performance. Another contribution is documenting recent advancements in nanosensor fabrication, design, and materials towards future research and development in this field.
A novel analytical tool was developed for the assay of the recently approved β3-adrenergic receptor agonist vibegron. This tool was also utilized in a cleaning validation process, in which the selection of a selective, sensitive, easy-to-use, and portable technique is preferred. For this purpose, a potentiometric solid-contact ion-selective electrode was fabricated for vibegron detection. Firstly, a smart and effortless approach was adopted for choosing the optimum electrochemical ionophore in the potentiometric sensor. The theoretical assumptions were practically verified by studying the selectivity of various electrodes with different studied ionophores towards vibegron and another structurally related molecule, mirabegron. The selected electrode showed a linear response over a concentration range of 1.0 × 10−7–1.0 × 10−2 M with a typical Nernstian slope of 57.89 mV/decade for the mono-cationic drug. The proposed sensor exhibited greenness, as verified via assessment by a recent tool, the Modified Green Analytical Procedure Index (MoGAPI), and the Analytical GREEnness (AGREE) tool. The proposed ion-selective electrode successfully quantified vibegron in tablet form without any remarkable interference from the tablet excipients. This work also demonstrated the first use of electrochemistry during a cleaning validation protocol for monitoring any drug residues to ensure the effective cleaning of pharmaceutical manufacturing equipment with satisfactory recovery values. The proposed sensor was found to be a more sustainable, portable and faster sensing platform for these residues than conventional chromatographic methods.
Selectively monitoring the mitochondrial dysfunction and viability of tumors is an important task for the treatment of cancer and is helpful for determining the appropriate radiotherapy and chemotherapy dose to minimize side effects. However, tumor-specific fluorescent probes that enable the visualization of mitochondrial dysfunction in tumor tissues have rarely been reported. Herein, a hypoxia-activated fluorescent probe (NTQ) was fabricated for selectively visualizing and monitoring mitochondrial dysfunction in tumors. NTQ was designed by linking a nitrobenzene unit to a quinolinium moiety to form an “A–π–A” electronic structure. Under hypoxic conditions, NTQ is reduced to ASQ with a “D–π–A” electronic structure to give enhanced deep-red fluorescence. ASQ was designed to have a positive charge and high affinity to RNA, thus targeting mitochondria in live cells and being able to detect reversible changes in the mitochondrial membrane potential by its relocation into the nucleolus. In this manner, NTQ enables the selective visualization of hypoxic tumors whilst simultaneously identifying mitochondrial dysfunction in tumors. The probe reveals that increasing the oxidative stress under hypoxia can efficiently lead to tumor cell apoptosis, and traditional anti-tumor drugs including paclitaxel and colchicine can lead to tumor cell apoptosis under hypoxic conditions. It is particularly noteworthy that tumor tissues were selectively illuminated by the NTQ probe and that the mitochondrial dysfunction in tumor tissues was successfully detected with NTQvia its migration from the mitochondria to the nucleolus.
Accurate quantification of microRNAs (miRNAs) is crucial for early cancer diagnosis, but conventional techniques, such as quantitative PCR and microarrays, are time-consuming, costly, and require complex instrumentation. In this study, we developed an integrated magnetic–microfluidic chemiluminescence (CL) platform for the rapid and sensitive detection of miR-21, a key biomarker associated with breast cancer. The platform integrates the magnetic nanoparticle-based capture of the target miRNA, performing sandwich hybridization and enzyme-driven chemiluminescence directly on the chip. This design enables efficient magnetic separation and produces a clean, low-background signal within the compact microchannel network. Using only 10 µL of sample, the assay delivers a quantitative chemiluminescent signal readout within 15 minutes and achieves a limit of detection of 0.3 pM with a linear dynamic range from 0.3 to 1000 pM (R2 = 0.98). Validation with exosomal RNA isolated from MCF-7 breast cancer cells confirmed the analytical feasibility of the platform. The proposed platform offers high sensitivity, rapid analysis, and compatibility with clinical exosome samples. Importantly, the integrated microfluidic system operates in a power-free manner, driven solely by capillary action and magnetic manipulation, making it suitable for point-of-care applications.
The illicit use of androgenic anabolic steroids, such as 17β-testosterone, in food-producing animals poses significant risks to animal welfare and consumer safety. Detecting exogenous administration of endogenous hormones like testosterone is particularly challenging, as the administered compound is chemically identical to naturally occurring hormones. In this study, we developed a metabolomics-based workflow using ultra-high-performance liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry to enhance detection of testosterone misuse in cattle. Serum samples from treated steers were analyzed using an untargeted metabolomics workflow combined with multivariate supervised modeling (OPLS-DA). Data processing with an optimized IPO-XCMS pipeline provided peak picking and alignment. OPLS-DA modeling provided robust class separation, correctly predicting the hold-out samples. Cross-validation and permutation testing further confirmed the model's stability and predictive reliability. Untargeted analysis identified three molecular features with high discriminatory power and positive correlation with the treatment, and a significant suppression of endogenous hormones (androstenedione, corticosterone, and progesterone) as part of a negative feedback response. Notably, these suppression effects persisted beyond the period of elevated testosterone responses. The proposed workflow offers a sensitive tool to strengthen regulatory surveillance by identifying both novel candidate markers and endocrine disruptions in suspected samples.
Quantitative mRNA expression levels are essential for differential and clinical diagnoses. In this work, we present an apurinic/apyrimidinic endonuclease 1 (APE1)-assisted SERS sensing platform for rapid and ultrasensitive detection of TK1 mRNA. This platform utilizes a hairpin probe that contains a TK1 mRNA capture sequence along with apurinic/apyrimidinic (AP) sites, which is specifically recognized and cleaved by APE1. Upon introduction of the target mRNA, hybridization occurs between the mRNA and the AP probe (HAP) within the hairpin structure, forming a double-stranded complex. APE1 then cleaves the HAP at the specific AP sites within the double-stranded complex, leading to a measurable change in the SERS intensity of the FAM-labeled HAP. Based on this principle, the developed SERS sensing platform demonstrates a highly linear response for TK1 mRNA detection across a wider range from 1 fM to 10 nM, with a detection limit (LOD) of 0.2 fM. Moreover, the SERS sensing platform shows great potential for the precise and quantitative detection of TK1 mRNA in human serum, which could be instrumental for mRNA-related research and the early clinical diagnosis of diseases.
Miniaturized mass spectrometry has emerged as a powerful analytical technique characterized by its portability, rapid analysis capability, and operational simplicity, making it particularly suitable for on-site detection across various fields. However, the accurate quantitative determination of multiple compounds in complex matrices remains challenging due to factors such as competitive ionization and limited ion storage capacity. In this study, a time-resolved thermal desorption continuous atmospheric pressure interface ion trap mass spectrometer (TRTD-CAPI-ITMS) coupled with an acetone-assisted photoionization source was developed for simultaneous detection of multiple cooling agents for ensuring product safety and quality control. To evaluate the performance of the system, time-resolved thermal desorption curves of cooling agent mixtures with varying boiling points and concentrations were systematically investigated. The prominent signals of all the cooling agents could be observed simultaneously at a thermal desorption time of 2.0 seconds. However, a key challenge was identified during simultaneous quantitation: non-linear concentration-dependent signal responses were observed with increasing cooling agent concentrations. Competitive ionization between the target cooling agents was confirmed as the primary cause of this phenomenon. To address this issue, two critical parameter adjustments were implemented: (1) reducing the sample load to decrease the number of competing analyte components in the ionization region, and (2) elevating the concentration of acetone dimer reagent ions to ensure sufficient reagent ions for effective ionization of the target cooling agents. As a result, competitive ionization was eliminated, and good linear calibration curves were obtained for all four cooling agents, with all linear correlation coefficients (R2) exceeding 0.99. Finally, the TRTD-CAPI-ITMS was applied to the quantitative determination of cooling agents in commercial dentifrice samples, with whole detection time less than 4 minutes, demonstrating the potential of TRTD-CAPI-ITMS as a powerful tool for field detection of cooling agents in complex matrices, with broad applicability in quality control and safety assessment across relevant industries.
Correction for ‘A portable fluorescent aptamer sensor for rapid quantitative detection of Hg2+’ by Jiayi Li et al., Anal. Methods, 2025, 17, 4461–4469, https://doi.org/10.1039/D5AY00115C.
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