Nitrite ion-induced fluorescence quenching of luminescent BSA-Au₂₅nanoclusters: mechanism and application

Abstract

Fluorescence quenching is an interesting phenomenon which is highly useful in developing fluorescence based sensors. A thorough understanding of the fluorescence quenching mechanism is essential to develop efficient sensors. In this work, we investigate different aspects governing the nitrite ion-induced fluorescence quenching of luminescent bovine serum albumin stabilized gold nanoclusters (BSA-Au NCs) and their application for detection of nitrite in urine. The probable events leading to photoluminescence (PL) quenching by nitrite ions were discussed on the basis of the results obtained from ultraviolet-visible (UV-Vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence measurements, circular dichroism (CD) spectroscopy, zeta potential and dynamic light scattering (DLS) studies. These studies suggested that PL quenching mainly occurred through the oxidation of Au(0) atoms to Au(i) atoms in the core of BSA-Au NCs mediated by nitrite ions. The interference caused by certain species such as Hg(2+), Cu(2+), CN(-), S(2-), glutathione, cysteine, etc. during the nitrite determination by fluorescence quenching was eliminated by using masking agents and optimising the conditions. Based on these findings we proposed a BSA-Au NC-modified membrane based sensor which would be more convenient for the real life applications such as nitrite detection in urine samples. The BSA-Au NC-modified nitrocellulose membrane (NCM) enabled the detection of nitrite at a level as low as 100 nM in aqueous solutions. This Au NC-based paper probe was validated to exhibit good performance for nitrite analysis in environmental water and urine samples, which makes it useful in practical applications.

π‐Expanded α,β‐Unsaturated Ketones: Synthesis, Optical Properties, and Two‐Photon‐Induced Polymerization

“…By etching the core of AuNCs, CN − , S 2− , and IO 3 − could quench the fluorescence and thus be determined 20. The oxidation‐induced quenching of the fluorescence by nitrite, H 2 O 2 , and ROS was also harnessed to develop “signal‐off” sensing systems 20c,21a,23. For most bioactive small molecules and drugs, they may disturb the interactions between the AuNC core and the BSA ligand, thus leading to fluorescence quenching.…”

One-pot synthesis of Au144(SCH2Ph)60 nanoclusters and their catalytic application

“…[1][2][3] The atomically precise metal nanoclusters (non-metallic, metal core size: 1-2 nm) give rise to unique physical and chemical properties that differ from the metal nanoparticles (metallic, size > 2 nm), making this type of nanomaterial very promising in optical properties and photovoltaics, as well as applications in fields such as catalysis and targeting agents. [4][5][6][7][8][9][10][11][12] For example, the Au n L m nanoclusters (where, L: organic ligand, and n, m represent the number of the gold atoms and ligands) are nonmetallic and often show a serial of UV-vis absorption bands due to the quantum size effects of extremely small size regime, in contrast with that of the conventional gold nanoparticles, which exhibit a distinct plasmon band at ca. 520 nm (for spherical particles).…”

Synthesizing a nano-composite of BSA-capped Au nanoclusters/graphitic carbon nitride nanosheets as a new fluorescent probe for dopamine detection

“…Owing to its high fluorescence and stability, BSA-capped AuNCs have been applied to detect various analytes, including small molecules (methotrexate, cysteine, glutathione, vitamin B12, dopamine and quercetin), heavy metal ions (Cu 2þ , Hg 2þ and Ag þ ), and proteins and proteases. They were also employed for cell labeling with their good biocompatibility, easy preparation, bio-conjugation, and long-wavelength emission [18]. Therefore, the combination of AuNCs and other materials can be considered as an effect way to provide highly selective and sensitive sensing platforms.…”