Copper nanocluster‐enhanced luminol chemiluminescence for high‐selectivity sensing of tryptophan and phenylalanine

Abstract

A remarkable method for the highly sensitive detection of phenylalanine and tryptophan based on a chemiluminescence (CL) assay was reported. It was found that fluorescent copper nanoclusters capped with cysteine (Cys-CuNCs) strongly enhance the weak CL signal resulting from the reaction between luminol and H O . Of the amino acids tested, phenylalanine and tryptophan could enhance the above CL system sensitively. Under optimum conditions, this method was satisfactorily described by a linear calibration curve over a range of 1.0 × 10 to 2.7 × 10 M for phenylalanine and 1.0 × 10 to 3.0 × 10 M for tryptophan, respectively. The effect of various parameters such as Cys-CuNC concentration, H O concentration and pH on the intensity of the CL system were also studied. The main experimental advantage of the proposed method was its selectivity for two amino acids compared with others. To evaluate the applicability of the method to the analysis of a real biological sample it was used to determine tryptophan and phenylalanine in human serum and remarkable results were obtained.

Effect of the Metal–Ligand Interface on the Chiroptical Activity of Cysteine‐Protected Nanoparticles

“…[ 56 ] Moreover, recent findings indicate the presence of weak absorption bands around 350–375 nm in cysteine‐Cu NPs with size in the range 2–3 nm. [ 57,58 ] On the other hand, the broad band at 285 nm, obtained in the present study for Cu‐Cys samples with pH = 6, is red shifted with respect to measurements performed on much larger Cu‐Cys NPs (>20 nm), displaying an aborsoption band at 265 nm. [ 59 ] In a related investigation, using the glutathione peptide instead of cysteine amino acid as a protecting ligand, Cu NPs with average size around 5.5 nm display a smooth absorption spectrum with a shoulder at 230–260 nm, reminiscent of the quasicontinuous electronic band structure and quantum confinement effects of the metal NPs.…”

A Review on Electrochemical Sensors and Biosensors Used in Phenylalanine Electroanalysis

“…In determining the essential amino acid Phe, optical methods were used, respectively: colorimetry [22,23]. UV and IR spectrophotometry [24], fluorescence [25][26][27][28][29], enhanced fluorescence [30], chemiluminescence [31][32][33]; separation methods, such as: gas chromatography [34], capillary electrophoresis, HPLC-high performance liquid chromatography [22,[35][36][37][38][39][40][41][42][43][44]; spectroscopic methods: Raman spectroscopy [45,46], laser-assisted spectroscopy [47], UV-Vis spectroscopy and chemometry [48]; UV−Vis and surface-enhanced Raman scattering [49], nuclear magnetic resonance [50] and circular dichroism spectroscopy [51]; mass spectrometry [22,34,41,52], fluorimetry [53].…”

Ligand functionalized copper nanoclusters for versatile applications in catalysis, sensing, bioimaging, and optoelectronics

“…117 Another molecule that has often been used as a ligand is L-cysteine. Borghei et al [118][119][120] have shown that Cu NCs can rapidly be prepared in the presence of cysteine at pH = 12 at RT, which exhibited a PL emission in the range of 410 to 580 nm depending on the cysteine concentration. Su and Liu 121 employed L-cysteine with an equal molar ratio with Cu 2+ to prepare Cu NCs with a pale red emission color under UV irradiation (365 nm).…”