A novel “off-on” fluorescence nanosensor for sensitive determination of sulfide ions based on carbon quantum dots and gold nanoparticles: Central composite design optimization

Sulfur-doped carbon dots synthesis under microwave irradiation as turn-off fluorescent sensor for Cr(III)

“…In this phenomenon, Cr(III) would absorb the emission light of S-CDs, but the excitation light would be constant since the addition of Cr(III) into the S-CDs solution. Therefore, the emission PL intensity of S-CDSs would be a turn-off (Shahbazi and Zare-Dorabei 2019;Mousavi et al 2020). Figure 6b shows no difference in absorption spectrum S-CDs both in absence Cr(III) and presence Cr(III).…”

A rapid, simple and ultrasensitive spectrofluorimetric method for the direct detection of metformin in real samples based on a nanoquenching approach

“…Recently, nanometre‐sized luminescent materials, including quantum dots (QDs), [ 43–45 ] carbon quantum dots (CQDs), [ 28 ] carbon dots (CDs), [ 41,49,52 ] graphene oxide (GO), [ 30,42 ] metal nanoclusters (MNCs; such as gold (Au) and silver (Ag) NCs), [ 39,40,46 ] metal nanoparticles (MNPs; such as Au and Ag NPs), [ 33,58–60 ] carbon nanotubes (CNs) [ 61 ] have been used as ideal luminescence probes in the biological systems studies. Among them, AuNPs and AgNPs have been widely used in various scientific fields including chemistry, medicine, and biochemistry.…”

“…These include high quenching yields (quenching coefficients 10 8 –10 10 M −1 cm −1 ), ease of preparation and their surface chemical modification, broad absorption bands, high photostability and photobleaching, good water solubility, and their size control by optimization of the synthesis conditions. [ 33,39,40,46,54,58–60 ] By dispersing these nanoparticles in an aqueous solution, they show great surface plasmon resonance absorption and, therefore, they can act as either ideal acceptor or donor for the FRET system.…”

A Sensitive, Simple and Direct Determination of Pantoprazole Based on a “Turn off-on” Fluorescence Nanosensor by Using Terbium-1,10-phenanthroline-silver Nanoparticles

“…These biosensors compared to traditional fluorescent probes give some advantages involving high quenching coefficients, broad absorption bands, ease of synthesis and their surface chemical modification, high photostability, photobleaching, good solubility and because of their unique electronic and optical properties, act as an ideal of either the acceptors or donors for the FRET process. 31,36,[38][39][40][41][42] FRET is a powerful and sensitive spectroscopic method, that is widely used to study intermolecular reactions, to determine the distance between two molecules (chromophores) by a few nanometers, as well as to measure various drugs and biological compounds. In this method, the excitation energy of a donor fluorophore in the electronic excited state is non-radiatively transferred to a convenient acceptor chromophore near to itself.…”