Chrono-colorimetric sensor array for detection and discrimination of halide ions using an all-in-one plasmonic sensor element

Most nanoparticle based colorimetric sensor array utilize several sensor elements and static response for discrimination of target analytes. This approach can be complicated and costly to synthesize or functionalize different nanoparticles for providing wide color variation. Herein, triangular silver nanoparticles (TSNPs) were used to develop a colorimetric sensor array by time-dimension responses. The principle of this sensor array is based on the diverse etching process of TSNPs in the presence of three halide ions, including bromide (Br^-), iodide (I^-) and chloride (Cl^-). Various etchings of TSNPs induced color changes at different reaction time intervals, which produced a colorimetric pattern for each ion. Therefore, using time dependent etching responses of TSNPs as a single sensing component can produce a wide color variation which can be distinguished by naked eyes. The colorimetric responses of TSNPs upon the addition of different concentrations of halide ions have been analyzed by PLS regression (PLS-R) and PLS discriminant analysis (PLS-DA). The analytical figures of merit confirmed that the developed chrono-colorimetric TSNPs -based sensor array is successful in both the discrimination and quantitative detection of halide ions. At the final step, the three halide ions were accurately determined in a real water sample, which verified the potential of the developed sensor in a real sample.

DNA-triangular silver nanoparticles nanoprobe for the detection of dengue virus distinguishing serotype

There is always a substantial effort to develop a point of care detection for a severe and acute disease like dengue. In this work, we have described the detection of serotype-specific dengue virus using multicolor triangular silver nanoparticles (TAg) which could be a potential diagnosis method to distinguish between serotype. Functionalized TAg was prepared with polyA₁₀ DNA through pH-mediated process. Further, it was characterized with Transmission Electron Microscopy (TEM), Ultra Visible-visible spectroscopy (UV-vis) and gel electrophoresis and its stability towards NaCl concentration. The colorimetric detection was carried out based on the interaction of TAg-DNA probe with specific complimentary strand which was designed to form a network assembly between DNA probes and sample RNA. The hybridization process was enhanced in presence of NaCl (0.4 M) which makes the hybridization process more stable over probe compared to un-hybridization. Therefore a simple and effective colorimetric method was developed to detect the different dengue serotype RNA with high sensitivity and specificity.