With the annual increases in the morbidity and mortality rates of tumors, the use of biomarkers for early diagnosis and real-time monitoring of tumor cells is of great importance. Biomarkers used for tumor cell detection in body fluids include circulating tumor cells, nucleic acids, protein markers, and extracellular vesicles. Among them, circulating tumor cells, circulating tumor DNA, and exosomes have high potential for the prediction, diagnosis, and prognosis of tumor diseases due to the large amount of valuable information on tumor characteristics and evolution; in addition, in situ monitoring of telomerase and miRNA in living cells has been the topic of extensive research to understand tumor development in real time. Various techniques, such as enzyme-linked immunosorbent assays, immunoblotting, and mass spectrometry, have been widely used for the detection of these markers. Among them, the detection of tumor cell markers in body fluids based on electrochemical biosensors and fluorescence signal analysis is highly preferred because of its high sensitivity, rapid detection and portable operation. Herein, we summarize recent research progress in the detection of tumor cell biomarkers in body fluids using electrochemical and fluorescence biosensors, outline the current research status of in situ fluorescence monitoring and the analysis of tumor markers in living cells, and discuss the technical challenges for their practical clinical application to provide a reference for the development of new tumor marker detection methods.

Aims This study was designed to explore the effect of the xanthine oxidase (XO) inhibitor allopurinol on cardiomyocyte apoptosis after myocardial infarction (MI) in a rat model. Methods and results MI was induced in rats by ligation of the anterior descending coronary artery. Survivors were randomly divided into three groups: sham operation group, MI group, and allopurinol group (50 mg kg⁻¹ day⁻¹). After 28 days, infarction size was measured. In non‐infarcted zones (NIZ), apoptosis index (AI) was measured by TUNEL [terminal deoxynucleotidyl transferase (TdT)‐mediated digoxigenin‐conjugated dUTP nick‐end labelling]; expression of Fas was detected by immunohistochemistry, and expression of XO and Caspase‐3 by western blot. In addition, XO and O₂⁻, OH‐scavenging activity of myocardial tissue in the NIZ were measured by colorimetry. Results suggest that AI and expression of Fas and Caspase‐3 in the NIZ were significantly depressed in the allopurinol group, compared with MI group; moreover, activity of XO was significantly decreased while O₂⁻ and OH‐scavenging activity were significantly increased in the allopurinol group. Ventricular remodelling was attenuated but there were no significant differences in infarct size or XO expression levels between the allopurinol and MI groups. Conclusion Our results suggest that allopurinol may inhibit cardiomyocyte apoptosis in the NIZ in rats. The potential mechanism could be related to its ability to reduce reactive oxygen species and to depress the expression of Fas and Caspase‐3.

Loop-mediated isothermal amplification (LAMP) is a rapid and high-yield amplification technology for specific DNA or RNA molecules. In this study, we designed a digital loop-mediated isothermal amplification (digital-LAMP)-functioning microfluidic chip to achieve higher sensitivity for detection of nucleic acids. The chip could generate droplets and collect them, based on which we could perform Digital-LAMP. The reaction only took 40 min at a constant temperature of 63 °C. The chip enabled highly accurate quantitative detection, with the limit of detection (LOD) down to 10² copies μL⁻¹. For better performance while reducing the investment of money and time in chip structure iterations, we used COMSOL Multiphysics to simulate different droplet generation ways by including flow-focusing structure and T-junction structure. Moreover, the linear structure, serpentine structure, and spiral structure in the microfluidic chip were compared to study the fluid velocity and pressure distribution. The simulations provided a basis for chip structure design while facilitating chip structure optimization. The digital-LAMP-functioning chip proposed in the work provides a universal platform for analysis of viruses.