In this work, we reported a simple rapid and point-of-care magnetic immunofluorescence assay for avian influenza virus (AIV) and developed a portable experimental setup equipped with an optical fiber spectrometer and a microfluidic device. We achieved the integration of immunomagnetic target capture, concentration, and fluorescence detection in the microfluidic chip. By optimizing flow rate and incubation time, we could get a limit of detection low up to 3.7 × 10(4) copy/μL with a sample consumption of 2 μL and a total assay time of less than 55 min. This approach had proved to possess high portability, fast analysis, high specificity, high precision, and reproducibility with an intra-assay variability of 2.87% and an interassay variability of 4.36%. As a whole, this microfluidic system may provide a powerful platform for the rapid detection of AIV and may be extended for detection of other viral pathogens; in addition, this portable experimental setup enables the development of point-of-care diagnostic systems while retaining adequate sensitivity.

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Lipid molecules contribute to a large extent to the regulation of cellular signaling, as cellular signals are generated primarily through the selective interaction of various cellular proteins with lipids in the plasma membrane. Hence the location, concentration, and duration of lipids on the cell membrane are critical for the selection of proteins and the initiation of signaling. To monitor the concentration and location of lipid molecules on the cell membrane, researchers have developed a variety of lipid biosensors that allow quantitative in situ visualization of lipid molecules in living cells based on lipid-binding domains with high specificity, sensitivity, and biocompatibility, providing a powerful tool for the study of cellular signaling mechanisms involving lipid molecules. In this review, we first introduced the emergence of lipid-binding domains and then focused on the practical considerations on how to implement the lipid sensor, including probe selection, modification, characterization, and imaging techniques. We then described experimental observables and the relevant physicochemical parameters in the context of single-molecule studies in cells. Finally, we presented our views on the future development of lipid sensors and methods for lipid quantification.