A rapid nucleic acid concentration measurement system with large field of view for a droplet digital PCR microfluidic chip.

Droplet digital polymerase chain reaction (ddPCR) is an effective technique, with unparalleled sensitivity, for the absolute quantification of target nucleic acids. However, current commercial ddPCR devices for detecting the gene chip are time consuming due to complex image stitching. To address this issue, we propose a universal concentration determination system and realize one-time gene chip imaging with high resolution. All the functional units are controlled by self-developed software using the PyQt5 module in Python. Without stitching technology, images of the ddPCR chip (28 mm × 18 mm) containing 20 000 independent 0.81 nL micro chambers can be obtained in less than 15 seconds, which saves about 165 seconds. A white laser light source (2 mW cm-2) was employed as a substitute for the mercury lamp. Its wavelength matches well with typical fluorescent dyes (e.g., HEX, ROX and Cy5), and thus it can strengthen the fluorescence intensity for weak signals. The results also demonstrated that the correlation coefficient for the measured concentration and theoretical value was above 99%, by testing the ddPCR products with COVID-19 virus. Such a system can greatly reduce the time required for image acquisition and DNA concentration determination, and thus is able to speed up the lab-to-application process for ddPCR technology.

Effect of adding shea butter stearin and emulsifiers on the physical properties of cocoa butter.

The aim of this study was to assess the feasibility of shea butter stearin (SBS) as cocoa butter equivalent (CBE). In this work, the optimal ratio of SBS and cocoa butter (CB) was evaluated by the solid fat content and deviation solid fat content. Emulsifiers added to SBS and CB blends were first screened based on ß polymorph level, and mixture regression experiment was designed to obtain the optimized compound emulsifiers ratio, finally the characterization of shea butter chocolate was evaluated by sensory evaluation and texture profile analysis (TPA). The best compatibility was obtained when the mixture ratio of SBS and CB was 20:80, where ΔSFC within a range of 1.5 was shown. The appropriate compound emulsifiers were soy lecithin: polyglycerol polyricinoleate: Tween 60 = 1:1:1. Both sensory evaluation and TPA test showed SBS and CB blends could improve the taste and texture of chocolate with proper emulsifiers addition.

In vitro simulated digestion and in vivo metabolism of chlorogenic acid dimer from Gynura procumbens (Lour.) Merr.: Enhanced antioxidant activity and different metabolites of blood and urine.

Gynura procumbens (Lour.) Merr. is an evergreen edible vine in southern China. The antioxidant activity and metabolites of chlorogenic acid dimer from Gynura procumbens (Lour.) Merr. were evaluated by the model of in vitro digestion and in vivo metabolomics approach, respectively. Moreover, metabolites of chlorogenic acid dimer in blood and urine of Sprague-Dawley rats were determined by HPLC-ESI-QTOF-MS/MS. In vitro digestion results suggested the antioxidant activity of the purified chlorogenic acid dimer was significantly enhanced after simulated digestion. Meanwhile, in vivo metabolism results showed that 7 and 20 new metabolites were observed in blood and urine, respectively, suggesting that hydrolysis along with methylation, glucuronidation and other reactions may all happen when the chlorogenic acid dimer entered the digestive and metabolic systems, which inducing and exhibiting various biological activities through metabolism. PRACTICAL APPLICATIONS: Gynura procumbens (Lour.) Merr. (GPM) is an evergreen edible vine with the effects of anticancer, anti-inflammatory, antiviral, depressurization, and antioxidation. As a health care vegetable, it is not usually eaten in daily life. Our current study shows that chlorogenic acid dimer extracted from GPM has a significant enhanced antioxidant ability after gastro-intestinal digestion in vitro, and their metabolites in vivo of urine is far more than that of blood, which may indicate that the chlorogenic acid dimer can be fully absorbed and decomposed through the gastro-intestinal digestion and metabolism. Thus, GPM could be used as a functional food ingredient for antioxidant enhancement to promote the economic value. The research also provides theoretical data for the intensive processing and utilization of GPM, as well as for the relative research on digestion and metabolism of edible plants.

Investigation of Lipid Metabolism by a New Structured Lipid with Medium- and Long-Chain Triacylglycerols from Cinnamomum camphora Seed Oil in Healthy C57BL/6J Mice.

In the present study, a new structured lipid with medium- and long-chain triacylglycerols (MLCTs) was synthesized from camellia oil (CO) and Cinnamomum camphora seed oil (CCSO) by enzymatic interesterification. Meanwhile, the antiobesity effects of structured lipid were investigated through observing the changes of enzymes related to lipid mobilization in healthy C57BL/6J mice. Results showed that after synthesis, the major triacylgeride (TAG) species of intesterificated product changed to LaCC/CLaC (12.6 ± 0.46%), LaCO/LCL (21.7 ± 0.76%), CCO/LaCL (14.2 ± 0.55%), COO/OCO (10.8 ± 0.43%), and OOO (18.6 ± 0.64%). Through second-stage molecular distillation, the purity of interesterified product (MLCT) achieved 95.6%. Later, male C57BL/6J mice were applied to study whether the new structured lipid with MLCT has the efficacy of preventing the formation of obesity or not. After feeding with different diets for 6 weeks, MLCTs could reduce body weight and fat deposition in adipose tissue, lower plasma triacylglycerols (TG) (0.89 ± 0.16 mmol/L), plasma total cholesterol (TC) (4.03 ± 0.08 mmol/L), and hepatic lipids (382 ± 34.2 mg/mice) by 28.8%, 16.0%, and 30.5%, respectively, when compared to the control 2 group. This was also accompanied by increasing fecal lipids (113%) and the level of enzymes including cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), hormone-sensitive lipase (HSL), and adipose triglyceride lipase (ATGL) related to lipid mobilization in MLCT group. From the results, it can be concluded that MLCT reduced body fat deposition probably by modulating enzymes related to lipid mobilization in C57BL/6J mice.

[Simultaneous determination of 11 mycotoxins in feeds by high performance liquid chromatography-tandem mass spectrometry].

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of 11 mycotoxins in feeds. The samples were extracted with acetonitrile, then cleaned up by multifunctional purification column filler and PRIME HLB solid phase extraction column. The 11 mycotoxins were separated on an Agilent Zorbax SB-C18 column (150 mm×2.1 mm, 3.5 µ m) with gradient elution program, and methanol-5 mmol/L ammonium acetate solution containing 0.1%(v/v) formic acid were used as mobile phases. The target compounds were detected under electrospray ionization (ESI) both in positive and negative modes with multiple reaction monitoring mode, and quantified by internal standard method. The results indicated that the 11 mycotoxins showed good linear relationships in their respective linear ranges, and the correlation coefficients were greater than 0.99. The limits of quantification (LOQs) were between 2.0 and 50.0 µ g/kg. The average recoveries were between 79.3% and 101.6% at three spiked levels (1, 2 and 5 times LOQs) with relative standard deviations (RSDs) of 5.9%-13.2% (n=5). The method is simple, rapid, sensitive, and can be used for the analysis of the 11 mycotoxins in feeds.