Paper-based microfluidic chip for rapid detection of SARS-CoV-2 N protein.

This research has developed a method for rapid detection of SARS-CoV-2 N protein on a paper-based microfluidic chip. The chitosan-glutaraldehyde cross-linking method is used to fix the coated antibody, and the sandwich enzyme-linked immunosorbent method is used to achieve the specific detection of the target antigen. The system studied the influence of coating antibody concentration and enzyme-labeled antibody concentration on target antigen detection. According to the average gray value measured under different N protein concentrations, the standard curve of the method was established and the sensitivity was tested, and its linear regression was obtained. The equation is y = 9.8286x+137.6, R2 = 0.9772 > 0.90, which shows a high degree of fit. When the concentration of coating antibody and enzyme-labeled antibody were 1 µg/mL and 2 µg/mL, P > 0.05, the difference was not statistically significant, so the lower concentration of 1 µg/mL was chosen as the coating antibody concentration. The results show that the minimum concentration of N protein that can be detected by this method is 8 µg/mL, and the minimum concentration of coating antibody and enzyme-labeled antibody is 1 µg/mL, which has the characteristics of high sensitivity and good repeatability.

Iridium oxide nanomonitors: clinical diagnostic devices for health monitoring systems.

The objective of this research is to demonstrate the potential of iridium oxide (IrOx) nanowires based device towards detection of proteins that are disease biomarkers. This device is based on electrical detection of protein biomarkers wherein an immunoassay is built onto the iridium oxide nanowires that in turn undergoes specific electrical parameter perturbations during each binding event associated with the immunoassay. Detection of two inflammatory proteins C-reactive protein (CRP) and Myeloperoxidase (MPO) that are biomarkers of cardiovascular diseases is demonstrated. The performance metrics of the device in response to the two biomarkers in pure form and in serum samples were evaluated and compared to standard ELISA assays. The methodology that has been adopted is based on measuring impedance and calibrating its change in magnitude with concentration of proteins. We demonstrate the following performance metrics: limits of detection up to 1 ng/ml for CRP and 500 pg/ml for MPO in pure and serum samples; linear dynamic range of detection from 10 ng/ml to 100 microg/ml for CRP and 1 ng/ml to 1 microg/ml for MPO and cross-reactivity contained at less than 10% of selective binding for both the inflammatory proteins. Iridium oxide has an ability to detect very small changes to the surface charge and this capability is utilized for achieving the performance metrics and forms the basis of the key innovations of this technology, which are, improving the selectivity and sensitivity of detection.

Lab-on-valve for the automatic determination of the total content and individual profiles of linear alkylbenzene sulfonates in water samples.

Methods for the total content and individual determination of linear alkylbenzene sulfonates (LAS) in water samples based on the use of a lab-on-valve (LOV) module alone or coupled to CE equipment, respectively, have been developed. The total content of LAS has been determined by intrinsic absorption measurements (DA method) and after reaction with a methyl orange-cetylpyridine chloride mixture (MO method) with detection limits (LODs) of 21 ng/L and 15 microg/L, respectively, quantification limits (LOQs) of 70 ng/L, 50 microg/L, and development times of 100 and 124 s, respectively. The method for individual separation-quantification of LAS at very low concentration is based on automatic SPE preconcentration in the LOV module coupled on-line with the CE equipment. The LODs and LOQs thus obtained range between 1-21 and 4-70 ng/L, respectively, with linear dynamic ranges from the LOQ to 10 microg/L. Preconcentration factors of 10,000 and high efficiency to eliminate interferents by SPE enable application of the method to treated effluent, waste, surface and sea waters.