Sensors & diagnostics最新文献

Monitoring metabolites in situ at the single-cell scale is important for revealing cellular heterogeneity and dynamic changes of cell status, which provides new possibilities for disease research. Benefiting from the advantages of both electrochemical and optical methods, electrochemiluminescence (ECL) has great potential in this field. However, developing real-time in situ imaging methods is full of challenges. In this study, an ECL imaging method for formaldehyde (FA), a kind of cellular metabolite, was developed based on the in situ generation of co-reactants at the electrode interface and was successfully applied to the monitoring of single-cell FA release. Amino groups can undergo a rapid nucleophilic addition reaction with FA to form amino alcohol intermediates, which can be used as co-reactants for tris(2,2′-bipyridyl)ruthenium(II) [Ru(bpy)₃²⁺] to significantly enhance the strength of ECL. Poly(amidoamine) (PAMAM), with a large number of amino groups, and reduced graphene oxide (rGO), with excellent electrical conductivity and electrocatalytic properties, were introduced as the modification layer on the electrode surface to realize the “turn on” detection of FA. This sensing method also eliminated the use of the classic toxic co-reactant tripropylamine (TPrA) and was further applied to in situ imaging of single-cell FA release. It successfully obtained ECL images at different time points after the stimulation of HeLa cells with thapsigargin (TG), revealing the change pattern in drug efficacy over time. This work proposes a new ECL imaging approach for real-time in situ monitoring of FA release from single cells, further broadening the application of ECL imaging in single-cell analysis.

Microfluidic chips designed to measure viscosity with extremely small amounts of liquids are expected to examine biological fluids, such as for the prediction of disease states and stress assessment, and for the evaluation of the physical properties of novel synthetic materials. However, these devices typically require sample volumes of several tens of μL or more, which has limitations when collecting biological samples from individuals nearly non-invasively. In this study, we fabricated a flow channel on a nonwoven fabric substrate with tailored hydrophilic and hydrophobic properties to enable viscosity measurements with the small-volume flow of aqueous solutions, such as 3 μL of saline. By measuring the electrical conductivity of the liquid using comb-shaped printed electrodes in contact with the flow path, we quantified the time and distance of liquid flow driven by capillary action to estimate solution viscosity. Using a mixture of glycerol and saline solution with varying viscosities, while maintaining a constant ion concentration, we demonstrated the capability to assess the relative viscosity of solutions. This was achieved by evaluating the correlation coefficient between the flow time and distance, and the net electrical conductivity, which is influenced by the viscosity and ion concentration of the solutions. This study lays the groundwork for developing a low-cost technique to measure the viscosity of solutions with a few μL, offering potential for routine health monitoring and disease prevention.

The constant need for cancer diagnosis in the early stages drives the development of contrast agents and imaging methods. Imaging agents have important roles in monitoring the progression and metastasis of cancers. Antibodies as biomolecules in conjugation with nanoparticles, radioisotopes, and drugs have been used as biomarkers for the early diagnosis/therapy of cancers due to their serum stability, affinity, and specificity. While antibodies are commonly used as nuclear medicine biomarkers, antibody-based contrast agent platforms have recently gained attention in X-ray computed tomography (CT) and magnetic resonance imaging (MRI). The developing antibody-based contrast agents have revolutionized cancer imaging techniques, particularly through MRI. Despite the promising advancements, some challenges and limitations need to be addressed for the extensive applications of these agents. Ongoing research is focused on overcoming challenges and limitations to enhance the efficiency and accuracy of these imaging methods. With continued advancements, antibody-based contrast agents hold immense potential in the early diagnosis and treatment of cancer. In this review, we summarize and categorize the recent progress in targeted imaging using antibody-based contrast agents by MRI and CT modalities.