Hao Li,Min Long,Huiyu Su,Lei Tan,Xiaowen Shi,Yumin Du,Yan Luo,Hongbing Deng
Immunoglobulin Y (IgY) proves advantageous to IgG in prophylaxis and diagnosis. Quantification of IgY is therefore becoming a topic of interest. Here, we demonstrate a piezoelectric biosensor with carboxymethyl chitosan (CMCS) as the immobilization matrix. Gelation and hydrophilic nature of CMCS are favored to form a crosslinked matrix for antibody immobilization, and a comparison was made between carboxymethyl cellulose (CMC) and CMCS to investigate the benefits of such substitution. Calibration from 500 ng/mL to 200 μg/mL was established in buffer with the detection limit (LOD) down to 270 ng/mL, confirming its feasibility. As-prepared biosensor effectively prevents non-specific binding of bovine serum albumin (BSA) and lysozyme . Each real-time assay took 15 min including sensor regeneration, which can be further reduced to 4 min for signal readout only, ready for both repeated measurements after regeneration and disposable devices. Thus, as-prepared biosensor offers a rapid, label-free and cost-effective approach for IgY quantification.
Yushen Liu,Juan Wang,Chao Zhao,Xiaoxiao Guo,Xiuling Song,Wei Zhao,Sijie Liu,Kun Xu,Juan Li
Listeria monocytogenes ( L. monocytogenes ) is one of the most common food-borne pathogens . The authors describe a sensitive and reliable multicolorimetric assay for L. monocytogenes using a sensing system based on TMB 2+ etching of gold nanorods . Apt-MNP was used as the capture probe, and IgY-BSA-MnO 2 NPs was chosen as an oxidase-like nano-artificial enzyme to oxidize TMB to generate TMB 2+ . Under the optimized conditions, the longitudinal shift of localized surface plasmon resonances had a linear correlation with the L. m onoc ytogenes concentration in the range between 10 to 10 6 cfu mL −1 . Meanwhile, the sensing system can generate vivid color responses as colorful as a rainbow, and the limit of detection is as low as 10 cfu mL −1 at a glance. Recoveries ranging from 97.4 to 101.3% are found when analyzing spiked food samples without pre-enrichment. In our perception, it shows promise in rapid instrumental and on-site visual detection of L. monocytogenes .
In this study, a novel colorimetric sensing platform was developed for the detection of S. aureus using dog immunoglobulin G (IgG) as the capture antibody and chicken anti-protein A immunoglobulin Y labeled with horseradish peroxidase (HRP-IgY) as the detection antibody. Dog IgG labeled with magnetic beads was used to capture S. aureus through the interaction between the Fc region of dog IgG and Staphylococcal protein A (SPA). HRP-IgY was introduced to recognize the residual SPA on the surface of S. aureus and to create a sandwich format, after which a soluble 3,3′,5,5′-tetramethylbenzidine (TMB) substrate was added. A stop solution was utilized to cease the enzymatic chromogenic reaction, and then optical density was read at 450 nm. Under optimal conditions, the proposed method displayed a low detection limit of 1.0 × 103 CFU mL−1 and a wide linear range of 3.1 × 103 to 2.0 × 105 CFU mL−1. This detection method exhibited high specificity against other foodborne bacteria. The recovery rates ranged from 95.2% to 129.2%. To our knowledge, this is the first report to employ dog IgG and chicken IgY as an antibody pair to detect S. aureus. This technique exhibits high application potential for S. aureus monitoring in various kinds of samples.
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