Smartphone based bacterial detection using biofunctionalized fluorescent nanoparticles
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We are describing immunochromatographic test strips with smart phone-based fluorescence readout. They are intended for use in the detection of the foodborne bacterial pathogens Salmonella spp. and Escherichia coli O157. Silica nanoparticles (SiNPs) were doped with FITC and Ru(bpy), conjugated to the respective antibodies, and then used in a conventional lateral flow immunoassay (LFIA). Fluorescence was recorded by inserting the nitrocellulose strip into a smart phone-based fluorimeter consisting of a light weight (40 g) optical module containing an LED light source, a fluorescence filter set and a lens attached to the integrated camera of the cell phone in order to acquire high-resolution fluorescence images. The images were analysed by exploiting the quick image processing application of the cell phone and enable the detection of pathogens within few minutes. This LFIA is capable of detecting pathogens in concentrations as low as 105 cfu mL−1 directly from test samples without pre-enrichment. The detection is one order of magnitude better compared to gold nanoparticle-based LFIAs under similar condition. The successful combination of fluorescent nanoparticle-based pathogen detection by LFIAs with a smart phone-based detection platform has resulted in a portable device with improved diagnosis features and having potential application in diagnostics and environmental monitoring.
KeywordsBiosensor Nanoparticles Bacterial diagnosis Immunofluorescence Point - of - care
We acknowledge Central Instrumentation Facility, Pondicherry University for SEM imaging and FT-IR characterization. We thank Dr.T.Vaidehi, Sundaram Medical Foundation Hospital, Chennai for providing clinical isolates of Salmonella spp. and Dr. Gagandeep Kang, Christian Medical College, Vellore for providing Escherichia coli O157. BP thanks Council of Scientific and Industrial Research (CSIR) for the award of Senior Research Fellowship.
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