title: Image-based ELISA on an activated polypropylene microtest plate--a spectrophotometer-free low cost assay technique.
abstract: In this communication, we report ELISA technique on an activated polypropylene microtest plate (APPµTP) as an illustrative example of a low cost diagnostic assay. Activated test zone in APPµTP binds a capture biomolecule through covalent linkage thereby, eliminating non-specific binding often prevalent in absorption based techniques. Efficacy of APPµTP is demonstrated by detecting human immunoglobulin G (IgG), human immunoglobulin E (IgE) and Aspergillus fumigatus antibody in patient's sera. Detection is done by taking the image of the assay solution by a desktop scanner and analyzing the color of the image. Human IgE quantification by color saturation in the image-based assay shows excellent correlation with absorbance-based assay (Pearson correlation coefficient, r=0.992). Significance of the relationship is seen from its p value which is 4.087e-11. Performance of APPµTP is also checked with respect to microtiter plate and paper-based ELISA. APPµTP can quantify an analyte as precisely as in microtiter plate with insignificant non-specific binding, a necessary prerequisite for ELISA assay. In contrast, paper-ELISA shows high non-specific binding in control sera (false positive). Finally, we have carried out ELISA steps on APPµTP by ultrasound waves on a sonicator bath and the results show that even in 8 min, it can convincingly differentiate a test sample from a control sample. In short, spectrophotometer-free image-based miniaturized ELISA on APPµTP is precise, reliable, rapid, and sensitive and could be a good substitute for conventional immunoassay procedures widely used in clinical and research laboratories.
authors.affiliation: Department of Chemical and Systems Biology, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India.
authors.forename: Shahila
authors.initials: S
authors.lastname: Parween
authors.forename: Pradip
authors.initials: P
authors.lastname: Nahar
mesh_terms: D000908:Antibodies, Fungal / Q000097:blood*; D001228:Aspergillosis / Q000097:blood* / Q000276:immunology; D001232:Aspergillus fumigatus / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000191:economics / Q000295:instrumentation*; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis*; D007074:Immunoglobulin G / Q000032:analysis*; D011126:Polypropylenes / Q000737:chemistry; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D000908:Antibodies, Fungal; D007074:Immunoglobulin G; D011126:Polypropylenes; D007073:Immunoglobulin E