Microfluidic systems provide a powerful platform for biological analysis and have been applied in many disciplines. However, few efforts have been devoted to plant cell study. In this article, an optimized culture of tobacco mesophyll protoplasts and their first polyethylene glycol-induced fusion in a microfluidic device are presented. Culture medium optimization and dynamics of protoplast growth including size change, organelle motion, and cell mass formation were also investigated microscopically in real-time. On-chip protoplast culture showed that the first division percentage of tobacco mesophyll protoplasts could be improved as high as up to 85.6% in 5 days using NT1 medium, and the percentage of small cell mass formation was more than 48.0% in 10 days. Meanwhile, chemical-induced fusion of tobacco mesophyll protoplasts was realized in 3-5 min and a 28.8% fusion rate was obtained, which was similar to the conventional fusion in a macro-scale environment. These results will be helpful for the development of microfluidics-based studies on manipulation and analysis of plant cells in a miniaturized environment, including cell growth and differentiation, gene isolation, and cloning.

Recent advances in video processing technology have provided a new approach to measuring the surface velocity of water flow (SVWF). However, most of the previous researches using video processing technology depended on tracers for target tracing, requiring spraying tracers in the measurement process. These methods are not convenient for velocity measurement. In this study, a dense optical flow method (Farneback optical flow method) was used to process the water flow video to get the estimated SVWFs. The estimated SVWFs were verified by the actual SVWFs measured by a portable propeller velocimeter. The regression analyses between the estimated SVWFs and the measured SVWFs were conducted. The coefficient of determinations (R2) of the estimated and the measured SVWFs in different test regions are between 0.81 and 0.85. The average relative errors of the estimated and the measured SVWFs in all test regions are no more than 6.5%. The results indicate that the method had a good accuracy in estimating the SVWF and is a feasible and promising approach to analyzing the surface velocity distribution of water flow.

This study demonstrates an improved magnetic protein microsphere-aided sandwich fluoroimmunoassay for the analysis of myoglobin and heart-type fatty acid binding protein (H-FABP), early protein markers associated with acute myocardial infarction. In preparation for the assay we constructed superparamagnetic human serum albumin (HSA)/gamma-Fe(2)O(3) microspheres, and grafted capture antibodies (monoclonal antimyoglobin 7C3 and anti-H-FABP 10E1) onto the protein microspheres using the avidin-biotin system. Then the antibody-carrying microspheres were used in a sequential sandwich fluoroimmunoassay along with detection antibodies (Alexa fluor594-labeled antimyoglobin 4E2 and FITC-labeled anti-H-FABP 9F3). The magnetic HSA/gamma-Fe(2)O(3) microspheres were characterized by scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectrophotometry, atomic absorption spectrophotometry, and vibrating sample magnetometry. Fluorescence images of the post-immunoassay microspheres recorded using an inverted fluorescence microscope showed that the average fluorescence intensity was correlated with the concentration of cardiac markers, in agreement with the results obtained by an F-4500 FL spectrophotometer; this indicated that the fluoroimmunoassay could be used to semiquantitatively detect both myoglobin and H-FABP. The detection limit was 10 ng/mL for myoglobin and 1 ng/mL for H-FABP.

No abstract

No abstract