Feng Wu

Multiplexed detection of influenza A virus subtype H5 and H9 via quantum dot-based immunoassay

Abstract A quantum dot-based lateral flow immunoassay system (QD-LFIAS) was developed to simultaneously detect both influenza A virus subtypes H5 and H9. Water-soluble carboxyl-functionalized quantum dots (QDs) were used as fluorescent tags. The QDs were conjugated to specific influenza A virus subtype H5 and H9 antibodies via an amide bond. When influenza A virus subtype H5 or H9 was added to the QD-LFIAS, the QD-labeled antibodies specifically bound to the H5 or H9 subtype viruses and were then captured by the coating antibodies at test line 1 or 2 to form a sandwich complex. This complex produced a bright fluorescent band in response to 365nm ultraviolet excitation. The intensity of fluorescence can be detected using an inexpensive, low-maintenance instrument, and the virus concentration directly correlates with the fluorescence intensity. The detection limit of the QD-LFIAS for influenza A virus subtype H5 was 0.016 HAU, and the detection limit of the QD-LFIAS for influenza A virus subtype H9 was 0.25 HAU. The specificity and reproducibility were good. The simple analysis step and objective results that can be obtained within 15min indicate that this QD-LFIAS is a highly efficient test that can be used to monitor and prevent both Influenza A virus subtypes H5 and H9.

Facile synthesis of high-quality CuInZnxS2+x core/shell nanocrystals and their application for detection of C-reactive protein

Highly photoluminescent (PL) CuInZnxS1+x nanocrystals (NCs) and CuInZnxS1+x/ZnS core/shell NCs were successfully synthesized by a facile colloidal method. First, a facile and reliable non-injection method for the synthesis of photoluminescent CuInZnxS2+x NCs was developed with inexpensive reagents. The relative PL quantum yields (QYs) of CuInZnxS2+x NCs could reach up to 30%, with tunable emissions in the range 580–780 nm. Then, CuInZnxS2+x/ZnS core/shell NCs were synthesized and showed greatly improved optical properties, the PL QY of the CuInZnxS2+x/ZnS NCs can reach up to 60%. Even in the near-infrared region, the PL QY still can achieve up to 45% due to the successful controlled red shift of PL during the ZnS shell growth process. More importantly, such core/shell NCs can be transferred into water successfully using amphiphilic oligomer (polymaleic acid n-hexadecanol ester) as a surface coating agent by an organic-aqueous phase transfer method and the PL QYs can be well controlled over 40%. Furthermore, a biosensor system (lateral flow immunoassays system, LFIA) for the detection of C-reactive protein (CRP) was developed by using this water-soluble CuInZnxS2+x/ZnS core/shell NCs as fluorescent label and a nitrocellulose filter membrane for lateral flow. The results showed that such CuInZnxS2+x/ZnS core/shell NCs were excellent fluorescent labels to detect CRP. The detection sensitivity for CRP could reach 1 ng mL−1.

Copolymerization of Eu(TTA)3Phen doped styrene and methyl methacrylate nanoparticles and use in quantitative detection of pepsinogen

High fluorescence intensity nanoparticles were prepared by copolymerization of Eu(TTA)3Phen doped styrene and methyl methacrylate. The fluorescent nanoparticles were used as labels for the quantitative detection of serum pepsinogens. Anti-pepsinogen I antibodies and anti-pepsinogen II antibodies were coated on the nitrocellulose membrane as test line 1 and test line 2 respectively. Serum pepsinogen I and pepsinogen II were detected simultaneously in one strip through sandwich immunoassay. This immunoassay strip can analyze the serum pepsinogens in one step and obtain results within 15 minutes. The limit of detection of this immunoassay strip for PG I and PG II standard analytes was 0.5 ng mL−1. The reproducibility and recovery tests shows that the quantitative results were accurate, and the strip can be used in clinical applications.