Detection limit

About: Detection limit is a research topic. Over the lifetime, 34379 publications have been published within this topic receiving 644817 citations. The topic is also known as: limit of detection & lower detection limit.

Iodine-Mediated Etching of Gold Nanorods for Plasmonic ELISA Based on Colorimetric Detection of Alkaline Phosphatase.

Abstract: Here, we propose a plasmonic enzyme-linked immunosorbent assay (ELISA) based on highly sensitive colorimetric detection of alkaline phosphatase (ALP), which is achieved by iodine-mediated etching of gold nanorods (AuNRs). Once the sandwich-type immunocomplex is formed, the ALP bound on the polystyrene microwells will hydrolyze ascorbic acid 2-phosphate into ascorbic acid. Subsequently, iodate is reduced to iodine, a moderate oxidant, which etches AuNRs from rod to sphere in shape. The shape change of AuNRs leads to a blue-shift of longitudinal localized surface plasmon resonance. As a result, the solution of AuNRs changes from blue to red. Benefiting from the highly sensitive detection of ALP, the proposed plasmonic ELISA has achieved an ultralow detection limit (100 pg/mL) for human immunoglobulin G (IgG). Importantly, the visual detection limit (3.0 ng/mL) allows the rapid differential diagnosis with the naked eye. The further detection of human IgG in fetal bovine serum indicates its applicability to the determination of low abundance protein in complex biological samples.

Chemiluminescence detection for hybridization assays on the flow-thru chip, a three-dimensional microchannel biochip.

Abstract: Chemiluminescence (CL) detection is seldom used in two-dimensional solid support microarray platforms because adequate sensitivity and spatial resolution is difficult to achieve. The three-dimensional ordered microchannels of the Flow-thru Chip increase both the sensitivity and spatial resolution required for quantitative CL measurements on microarrays. Enzyme-catalyzed CL reactions for the detection of hybridizations on microchannel glass were imaged using a CCD camera. Signal uniformity, sensitivity, and dynamic range of the detection method were determined. The relative standard deviation of signal intensities across an array of 64 spots was 8.1%. A detection limit of 250 amol of target with a linear dynamic range of 3 orders of magnitude was obtained for a 3-h assay. Similar to two-color fluorescence measurements, multiple enzyme labels were employed to demonstrate two-channel chemiluminescence. A unique method for measuring the relaxation time of a chemiluminescent species is also described.

Metal-organic framework templated synthesis of Co3O4 nanoparticles for direct glucose and H2O2 detection.

Abstract: Co(3)O(4) nanoparticles (NPs) with an average diameter of about 20 nm were synthesized by using MOFs as a template. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the as-prepared Co(3)O(4) NPs. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to confirm the structure of the Co(3)O(4) NPs. Then the Co(3)O(4) NPs were modified on a glassy carbon electrode (GCE) to obtain a non-enzymatic glucose and H(2)O(2) sensor. The NPs show electrocatalytic activity toward oxidation of glucose and H(2)O(2) in alkaline medium. For glucose detection, the developed sensor shows a short response time (less than 6 s), a high sensitivity of 520.7 μA mM(-1) cm(-2), a detection limit of 0.13 μM (S/N = 3), and good selectivity. The high concentration of NaCl does not poison the electrode. Its application for the detection of glucose in a human blood serum sample shows good agreement with the results obtained from the hospital. Furthermore, the proposed sensor was used for the detection of H(2)O(2). The results indicate that the detection limit and sensitivity for H(2)O(2) are 0.81 μM and 107.4 μA mM(-1) cm(-2), respectively. Determination of H(2)O(2) concentration in a disinfectant sample by the proposed biosensor also showed satisfactory result. The high sensitivity and low detection limit can be attributed to the excellent electrocatalytic performance of the as-prepared Co(3)O(4) NPs. These results demonstrate that the as-prepared Co(3)O(4) NPs have great potential applications in the development of sensors for enzyme-free detection of glucose and H(2)O(2).