Fast and sensitive smartphone colorimetric detection of whole blood samples on a paper-based analytical device.

BACKGROUND: Methods based on paper-based analytical devices (PAD) and smartphone photographic colorimetric detection have become representative instrument-independent point-of-care testing (POCT) platforms due to their low cost and simplicity. However, the detection of target components from whole blood sample still presents challenges in terms of field preparation of small amounts of blood sample and detection sensitivity. This paper presents a rapid online processing method for whole blood samples on PAD based on plasma separation membrane (PSM), and combined with electrokinetic stacking and selective chromatic reaction. Real-time smartphone-based colorimetric detection of free hemoglobin (FHb) and human serum albumin (HSA) was successfully demonstrated. RESULTS: With the proposed method, both detections for low and high concentration analytes could be implemented. The limits of detection of 16.6 mg L-1 for FHb and 0.67 g L-1 for HSA were obtained, respectively, with RSD below 8 %. The reliability of the method was verified by the recovery test and desktop spectrophotometric method. The detection results for real blood samples were in agreement with that by clinical methods. SIGNIFICANCE AND NOVELTY: The PAD method is inexpensive, simple and fast, and detection of a whole blood sample of 5 µL can be finished in 5 min. This work shows that POCT of biomarkers from whole blood with PAD is possible without using any desktop facilities.

Paper-based sample processing for the fast and direct MS analysis of multiple analytes from serum samples.

Amino acids are closely related to human health, and their rapid determination is important for the rapid diagnosis, timely treatment, and assessment of serious diseases. In this work, we propose a novel paper-based sample-processing device combined with isotope-dilution MS for the fast analysis of 11 amino acids from blood samples. By using an isoelectric focusing electrokinetic separation method, without the aid of carrier ampholytes and the addition of inhibitors, this approach uses only the characteristic of the isoelectric point of the target amino acids to achieve separation and purification from other coexisting components in the medium; it can meet the requirements for mass spectrometry detection. Driven by a DC voltage, a stable and sharp pH gradient (pH 3-10.5 over 5 mm) can be established in a glass-fiber paper-based fluidic channel with a MS-friendly electrolyte. Amphoteric species can be well separated from the complex blood matrix and concentrated into a narrow band in the channel within 2 min, which is 20 times faster than a commercial kit method. The method can be applied to both liquid and dry spot samples, and the cleaned sample band can be simply dissolved for direct IDMS detection in ESI MRM mode. This method is a promising strategy for the rapid MS-based detection of amino acids from serum without pre-separation via liquid chromatography.

[Effect of neuronal differentiation induced by nerve growth factor on the tolerance-dosage of ultraviolet radiation of PC12 cells].

OBJECTIVE: To evaluate the effect of neuronal differentiation induced by nerve growth factor (NGF) on the tolerance-dosage of ultraviolet radiation of PC12 Cells. METHODS: Neuron-differentiated PC12 cells and untreated PC12 cells were exposed to different ultraviolet radiation dosage of 10, 30, 60, 80, 100, and 200 mJ/cm2. Cell survival rates were determined by MTT assay. RESULTS: Neuron-differentiated PC12 cells had increased tolerance dose to ultraviolet radiation with noticeable apoptosis at the radiation dose of 100 mJ/cm2 in contrast to 30 mJ/cm2 for normal PC12 cells. CONCLUSION: Neuronal differentiation exerts the effect of increasing the tolerance dose of PC12 cells to ultraviolet radiation.

Numerical calculation of the sound field focused by acoustic lens with an arbitrary axisymmetric sound speed distribution.

The expressions that describe the sound field focused by an acoustic lens with different sound speed distribution (SSD) in lens are given. Numerical calculation results are presented, in which the axial and lateral sound pressure distributions and the -3 dB sound beam profile along the focused field are given out for three types of the acoustic focused lens with revolving-arc curved outer surface and four types' axisymmetric SSD. It is shown that, when sound beam is focused by a lens with SSD, the best focal point moves away from the lens and achieves a large focal region compared with the no-SSD case. The maximum axial focused intensity at the best focal point is smaller than that of the no-SSD case, but the focused beam width at the best focal point is larger than that of the no-SSD case. The larger the coefficient of the SSD, the larger the focused beam width and the larger focal region, but the divergent angle is almost the same.