Highly sensitive detection of dengue biomarker using streptavidin-conjugated quantum dots

Abstract

A highly sensitive immunosensor using streptavidin-conjugated quantum dots (QDs/SA) was developed to detect dengue biomarker of non-structural protein 1 (NS1) at very low concentration, so that it can probe dengue infection even in the early stage. The QDs/SA were first bound to biotinylated NS1 antibody (Ab) and the QDs/SA-Ab conjugates were then used to detect the NS1 antigen (Ag) in the Ag concentration range of 1 pM to 120 nM. The formation of QDs/SA-Ab and QDs/SA-Ab-Ag conjugates was confirmed by the measurements of field emission scanning electron microscopy (FF-SEM), field emission transmission electron microscopy (FE-TEM), dynamic light scattering (DLS), and zeta-potential. Fluorescence emission spectra of QDs/SA-Ab-Ag conjugates showed that the magnitude of fluorescence quenching was linearly proportional to the NS1 Ag concentration and it nicely followed the Stern–Volmer (SV) equation in phosphate buffer solution. However, in human plasma serum solution, the fluorescence quenching behavior was negatively deviated from the SV equation presumably due to interference by the serum component biomolecules, and it was well explained by the Lehrer equation. These results suggest that the current approach is promising because it is highly sensitive, fast, simple, and convenient, and thus it has a potential of application for point-of-care.

Design and Fabrication of a Nanobiosensor for the Detection of Cell-Free Circulating miRNAS-LncRNAS-mRNAS Triad Grid

“…It is also known that photoinduced electron transfer from an excited QDs to a nearby compound with an energy intermediate to the valence and conduction band edge states causes the fluorescence quenching of QDs and results in a decrease in fluorescence intensity. 24,25 The developed nanoconjugates were then analyzed for selective target detection and applicability in filtered plasma samples spiked with target RNA amplicons. The nanoconjugates have oligonucleotide probes on the surface, which are complementary to the targeted miRNA, lncRNA, and mRNA and ensure selective binding.…”

Graphene Nanobeacons with High‐Affinity Pockets for Combined, Selective, and Effective Decontamination and Reagentless Detection of Heavy Metals

“…To shed more light on the nature of the interactions, we probed the PL decay curves with and without metals and analyzed the PL quenching results with the Stern-Volmer plots of F0/F versus metal concentration using the functions based on bimolecular theory. The derived Stern-Volmer-constants (K sv ) were 0.046 nm −1 (4.6 × 10 7 m −1 ) and 0.022 nm −1 (2.2 × 10 7 m −1 ) for Pb 2+ and Cd 2+ , respectively (Figure S16, Supporting Information), being in the order of antigen antibody-interactions (0.058 nm −1 [88] or 10 6 -10 9 m −1 [40,49] ). Indeed, such K SV constants are two or three orders of magnitude larger than other CDs sensors, [45,82,86] but also than other potent sensors based on fluorescent MOFs, [33,89,90] all ranging between 3 × 10 4 and 4 × 10 5 m −1 .…”

A Novel Enzyme-Free Ratiometric Fluorescence Immunoassay Based on Silver Nanoparticles for the Detection of Dibutyl Phthalate from Environmental Waters

“…As shown in Figure 1 A,B, we can see that AgNPs have a structure with a roughly spherical shape and a size of about 30 nm, which increased to 50 nm upon conjugation with Ab 2 . This increase was due to the agglomeration of particles that is often caused by the bonding between Ab 2 and AgNPs [ 31 ]. As seen from Figure 1 C, the ultraviolet absorption peak of AgNPs@Ab 2 was obviously blue-shifted, indicating the successfully conjugations of AgNPs and Ab 2 [ 29 ].…”