Sharif Digital Repository

A simple and effective ratiometric fluorescence sensor for selective detection of dopamine (DA) in alkaline media has been developed by simply mixing thioglycolic acid (TGA) functionalized orange fluorescent cadmium telluride (CdTe) quantum dots (QDs) with amino-functionalized blue fluorescent carbon nanodots (CDs). Under a single excitation wavelength of 365 nm, the sensor exhibits dual-emissions centered at 445 and 603 nm. The fluorescence of CdTe QDs is selectively quenched by DA, whereas the fluorescence of CDs is insensitive to the analyte. In the presence of different amounts of DA, the variations in the dual emission intensity ratios exhibit a continuous color change from pink to... 

In the present study, a ratiometric fluorescent sensor array as an artificial tongue has been developed on a nanopaper platform for chemical discrimination applications. The bacterial cellulose (BC) nanopaper was utilized for the first time as a novel, flexible, and transparent substrate in the optical sensor arrays for developing high-performance artificial tongues. To fabricate this platform, the hydrophobic walls on the BC nanopaper substrates were successfully created using a laser printing technology. In addition, we have used the interesting photoluminescence (PL) properties of an immobilized ratiometric probe (carbon dot-Rhodamine B (CD-RhB) nanohybrids) on the nanopaper platform to... 

A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual... 

Signal generation techniques for visual detection of analytes have received a great deal of attention in various sensing fields. These approaches are considered to be advantageous when instrumentation cannot be employed, such as for on-site assays, point-of-care tests, and he althcare diagnostics in resource-constrained areas. Amongst various visual detection approaches explored for non-invasive quantitative measurements, ratiometric fluorescence sensing has received particular attention as a potential method to overcome the limitations of intensity-based probes. This technique relies on changes in the intensity of two or more emission bands (induced by an analyte), resulting in an effective... 

A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual... 

Here, the carboxamide ligand N-(thiazole-2-yl) picolinamide (L) was synthesized in an ionic liquid tetrabutylammonium bromide (TBAB) as the benign reaction medium. The sensitivity of L towards different metal-ions was investigated, and a comprehensive, logical optical investigation was conducted for the IIB transition metal ions, Hg2+, Cd2+ and Zn2+, based on off-on switch sensor protocols. In the absence of these metal ions, L showed weak emission only, but fluorescence intensity increased considerably upon their addition to a sensitivity range of 10-6 M. This phenomenon was enhanced significantly in the presence of Zn2+ compared to other metal ions, likely due to the coordination of...