Anti-Horseradish Peroxidase polyclonal antibody [Alexa Fluor® 488]

In this work, a label-free colorimetric assay was developed for the determination of urine glucose using smartphone ambient-light sensor (ALS). Using horseradish peroxidase-hydrogen peroxide-3,3',5,5'-tetramethylbenzidine (HRP-H2O2-TMB) colored system, quantitative H2O2 was added to samples to-be-determined for deepest color. The presence of glucose oxidase in urine led to the formation of H2O2 and the reduction of TMBred. As a result of this, the color of the urine faded and the solution changed from deep blue to light blue. We measured the illuminance of the transmitted light by a smartphone ambient light sensor, and thereby color changes were used to calculate the content of urine glucose. After method validation, this colorimetric assay was practically applied for the determination of urine samples from diabetic patients. Good linearity was obtained in the range of 0.039-10.000 mg/mL (R-2 = 0.998), and a limit of detection was 0.005 mg/mL. Our method was had high accuracy, sensitivity, simplicity, rapidity, and visualization, providing a new sensor to be potentially applicable for point-of-care detection of urine glucose.

Herein a versatile photoelectrochemical (PEC) immunoassay platform for sensitive and specific screening of tumor biomarkers (carcinoembryonic antigen; CEA) was innovatively designed using hollow cadmium sulfide (H-CdS) as photoactive matrix based on immunomagnetic separation. Experimental results reveal that the hollow-structure prepared by template hydrothermal-etching method endowed the CdS with better photocurrent intensity compared to the traditional CdS nanoparticles. Upon addition of target CEA, a sandwiched immunoreaction was carried out between anti-CEA capture antibody-conjugated immunomagnetic bead (IMB) and horseradish peroxidase (HRP)-labeled anti-CEA detection antibody, accompanying the immunocomplex formation of the IMB-antibody/CEA/HRP-labeled antibody (IMB-CEA-HRP). Followed by magnetic separation, the carried HRP on the sandwich structure triggers enzymatic bioetching of H-CdS, thus resulting in decreasing photocurrent intensity. The H-CdS-based PEC sensing system exhibited satisfying photocurrent responses toward target CEA within the working range from 0.02 ng mL(-1) to 50 ng mL(-1) at a low detection limit of 6.12 pg mL(-1). Combined with magnetic immunoassay, this sensing platform has the advantages of high precision, great anti-interference ability, and acceptable accuracy. Overall, this research not only provides an efficient strategy for the activity of CdS with a well-defined hollow-nanostructures but also sheds light on the development of enzyme-triggered bioetching technology for traditional PEC immunoassay.