Green synthesis of highly fluorescent Au(i)@Ag₂/Ag₃-thiolate core–shell particles for selective detection of cysteine and Pb(ii)

Abstract

Giant Au(I)@Ag2/Ag3-thiolate clusters with strong fluorescence (λex 400 nm, λem 564 nm, and quantum yield 8.3%) have been prepared in aqueous medium from glutathione and corresponding precursor salts at neutral pH under sunlight. An intriguing synergism between Au(I)core and Ag(0)shell imparts long-term stability to the fluorescent giant clusters (synthesized with a chemically green method) due to drifting of electron density towards core from shell. The strong fluorescence is selectively damped by cysteine (Cys) leaving aside all other essential amino acids ("Turn Off"). This quenched fluorescence is restored again on introducing Pb(II) ions in the system ("Turn On"). No other metal ion can cause such a recovery of the lost fluorescence. Such "Turn Off" and "Turn On" fluorescence helps in the design of a selective Cys as well as Pb(II) sensor in one pot. Detection of Cys and Pb(II) down to 5 × 10(-8) M and 15 × 10(-8) M, respectively, is possible following the present strategy.

Aggregation induced emission of gold(i) complexes in water or water mixtures

“…This concept has been widely used and there are numerous examples of a variety of applications for AIE materials. [16][17][18][19][20] Most of the AIE active molecules in literature are organic and this phenomenon has been less explored for metal complexes. Similar to organic compounds, TMC also exhibit rich optical and luminescent properties usually associated with metal centers and their stability in common organic solvents.…”

Solvent Polarity-Dependent Behavior of Aliphatic Thiols and Amines toward Intriguingly Fluorescent AuAgGSH Assembly

“…In this case, the Ag clusters undergo aggregation due to lack of a stabilizing factor. 40 XPS peaks appear at lower regions, i.e., 367.03 and 373.02 eV for Ag(0) 3d 5/2 and Ag(0) 3d 3/2 , respectively. For CH 3 (CH 2 ) 9 NH–WAuAgGSH, the peaks of Au appeared at 84.06 and 87.6 eV for Au(0) 4f 7/2 and Au(0) 4f 5/2 , respectively.…”

Intriguing cysteine induced improvement of the emissive property of carbon dots with sensing applications

“…Thus, the high pH value of this technique definitely restricts in vivo detection/measurement of Cys. Though there are different reports for Cys sensing by different groups, [11][12][13][14][15][16][17][18][19][20][21][22][23][58][59][60] there is no report so far for Cys sensing through carbon dot (CD) formation, which has inherent novelty from the selectivity point of view (no other thiol containing compound caused interference). Generally, the pathological tests are done 0.01-20 mM 1 0 n M in vitro; thus, this technique may be helpful.…”

“…[7][8][9] Imbalance of Cys causes many physical hazards. 16 Recently, some fluorometric detection methods have been prescribed in terms of the employment of fluorescent dyes, 17,18 fluorescent clusters, 19 and fluorescence-coupled HPLC techniques. 10 Thus, the search for a Cys sensor has become an important job for scientists.…”

“…Most of the sensing techniques follow a colorimetric pathway, 11 electrochemical methodology, 12 UV-vis spectroscopy, 13 mass spectrometry, 14 resonance light scattering (RLS) technique, 15 and circular dichroism technique. 16 Recently, some fluorometric detection methods have been prescribed in terms of the employment of fluorescent dyes, 17,18 fluorescent clusters, 19 and fluorescence-coupled HPLC techniques. 20,21 Moreover, fluorescent water soluble quantum dots (QDs) have been applied for low dose Cys detection.…”