Seven potential variables, pretreatment temperature, pretreatment time, concentration of OH -, concentration of H + , extraction temperature, extraction time, and skin/water ratio, were investigated by a 2 7-3 fractional factorial design to identify critical control factors for pollock skin gelatin extraction, and 3 responses, yield, gel strength, and viscosity, were evaluated. The results suggest that 4 variables, pretreatment temperature, concentration of OH -, concentration of H + , and extraction temperature, have significant effects on gelatin extraction, and these key factors were then selected for the subsequent optimization using response surface methodology with a 4-factor, 5-level central composite rotatable design. It suggests that a concentration of OH -at 0.25 mol/L, a concentration of H + at 0.09 mol/L, a pretreatment temperature at 2°C, and an extraction temperature at 50°C, will give the highest values for the 3 responses. The predicted responses for these extraction conditions are that the yield will be 18%, gel strength will be 460 g, and viscosity will be 6.2 cP.

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Herein we report a quantitative, multiplex assay for disease markers in plasma based on an integrated setup of a portable scanner and a disposable paper-based analytical device (PAD). The quantitative analysis relies on the digital colorimetric reading of the three-layer PAD with 30 assay sites for performing respective chromogenic reactions for plasma uric acid, glucose, and triglyceride, which are considered as important risk factors for cardiovascular diseases. A portable scanner with WiFi transmission capability was used to produce high-quality color images of the PADs and wirelessly transfer them to a smartphone or other mobile devices for data processing. The concentrations of biomarkers in both standard solutions and plasma samples can be directly obtained using a custom-designed smartphone app that is also capable of constructing calibration curves. The detection limits of uric acid, glucose, and triglyceride were determined to be 0.50 mg/dL, 0.84 mmol/L, and 14 mg/dL, respectively, which are below the normal limits and adequate for clinical validation. Owing to the distinct advantages-simple, portable, and costeffective-this mobile assay protocol can be used for point-of-care (POC) settings or resource-limited situations, and potentially for the diagnosis and prevention of infectious diseases.

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