A novel colorimetric sensing platform for the detection of S. aureus with high sensitivity and specificity.

Yun Zhang,Chenguang Zhang,Lin Zhang,Jinjuan Qiao,Miaomiao Zhang,Wenqing Tan,Jiajia Xing,Shuyou Shi,Huan Yuan

doi:10.1039/c9ra05304b

Abstract

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.

Highlights

Staphylococcus aureus (S. aureus) is one of the most common food-borne pathogens, and can cause various infections ranging from scalded skin syndrome to life-threatening septicemia.[1,2,3] Annually, S. aureus causes about 241 000 cases of foodborne illnesses, which pose a signi cant threat to public health and food safety.[4,5] It is important to develop effective detection strategies for S. aureus.To date, several detection strategies have been developed to monitor S. aureus
The magnetic beads (MBs)-dog Immunoglobulin G (IgG)-S. aureus complex was dispersed in 100 mL of horseradish peroxidase (HRP)-IgY (0.5 mg mLÀ1) and the entire mixture was rotated for 30 min
A and A0 were gradually increased with increasing amounts of IMBs. This may be attributed to non-speci c binding of HRP conjugated chicken anti-protein A IgY (HRP-IgY) onto IMBs caused by the increase in the amount of IMBs

Summary

Introduction

Staphylococcus aureus (S. aureus) is one of the most common food-borne pathogens, and can cause various infections ranging from scalded skin syndrome to life-threatening septicemia.[1,2,3] Annually, S. aureus causes about 241 000 cases of foodborne illnesses, which pose a signi cant threat to public health and food safety.[4,5] It is important to develop effective detection strategies for S. aureus.To date, several detection strategies have been developed to monitor S. aureus. Due to its low-cost, high sensitivity and high throughput application, ELISA is the most frequently used method for antigen detection.[11,12] few ELISA-based methods have been used to detect S. aureus cells. This is likely due to the lack of suitable antibody pairs, which limit the development of speci c immunoassays for S. aureus.[13] Since mammalian monoclonal or polyclonal antibodies against S. aureus can bind to protein G producing Streptococcus by interactions between the Fc region of mammalian Immunoglobulin G (IgG) and protein G,14 the speci city of detection is not guaranteed. It is of particular signi cance to select a feasible antibody pair for an ELISA-based detection of S. aureus

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Conclusion