Abstract
Colorimetric immunoassay is a widely used method for pathogen detection. The conventional implementation of immunoassays in 96-well plates often encounters difficulties for samples with low concentrations. In this study, the detection performance has been improved using a cellulose acetate membrane for target enrichment and immunodetection. For this end, a compact multichannel filtration device was fabricated using a 3D printer for sample loading. Background effects of the membrane were greatly minimized after pretreatment with a sodium hydroxide solution to significantly reduce non-specific binding. The colorimetric result of the immunodetection of Escherichia coli strain K12 (E.coli K12) was recorded and quantitatively analyzed with a smartphone camera. A limit of detection was calculated as 40 cfu (colony forming unit)/ml, two orders of magnitude more sensitive than that obtained on 96-well plates with standard protocol. The developed approach features an integrated sample enrichment scheme, reduced reagents consumption, multiple channels for parallel processing and no reliance on advanced laboratory instruments, thereby providing potential for a low-cost and easy-to-use immunodetection system.
Highlights
Pathogen detection is an important aspect of biosafety assessment in the fields of water supply [1,2,3], air quality management [4,5,6] and food storage [7,8,9,10]
The complexity resulted from sample prepa ration, strict requirement of temperature control and high dependence on advanced instruments make the polymerase chain reaction (PCR) method challenging to operate and unsuitable for low cost applications [15]
It is of significance to integrate the sample enrichment and colorimetric immunodetection on the same substrate for simplifying the analysis process and improving the detection performance
Summary
Pathogen detection is an important aspect of biosafety assessment in the fields of water supply [1,2,3], air quality management [4,5,6] and food storage [7,8,9,10]. The colorimetric immunodetection of pathogens can be carried out in 96-well plates ac cording to commercial protocols It is not recommended for detecting samples with concentrations lower than 104 - 105 cfu/ml [8]. As the lateral flow based device cannot work efficiently for sample enrichment, it has a limited advantage in detecting low concentration of pathogens and has been mostly employed for qualitative or semiquantitative applications [18]. The detectable concentration of E.coli O157:H7 using lateral flow immuno assays was usually higher than 104-105 cfu/ml [19,20] As another membrane based application, the vertical flow immunoassay shows overwhelming advantage in combining sample purification and enrichment [21,22,23,24]. The contents are as follows: (1) The design and fabrication of the compact multichannel filtration device; (2) the minimization of background effects of membranes; (3) the assessment of E.coli K12 collection and distribution on membranes; (4) the quantitative analysis of immunodetection results recorded with a smartphone camera
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
