Solvent-driven thiol protected luminescent cobalt nanoclusters

Interaction of Atomically Precise Thiolated Copper Nanoclusters with Proteins: A Comparative Study

A facile synthesis of glutathione-stabilized copper nanoclusters (CuNCs) is carried out in H2O/ tetrahydrofuran medium. The photophysical and morphological studies performed with as-synthesized CuNCs revealed the formation of green-emissive, stable, and smaller nanoclusters. The precise composition of these as-synthesized CuNCs was predicted with the aid of electrospray ionization mass spectrometry analysis as Cu12(SG)9. Furthermore, the systematic studies of the interaction of synthesized CuNCs with three plasmatic proteins, namely, bovine serum albumin (BSA), lysozyme (Lys), and hemoglobin (Hb) have been performed by using a series of spectroscopic studies. The conformational changes in these proteins upon interacting with CuNCs and their binding stoichiometries have been investigated from the combination of UV-visible and steady-state fluorescence measurements. The changes in the microenvironment of proteins caused by CuNCs were investigated by circular dichroism spectroscopy. Among these three proteins, BSA and Lys had a minor effect on the luminescence of CuNCs, which makes them suitable candidates for biological applications. There are no drastic changes in the microenvironment of NCs as well as proteins because of the possibilities of weak electrostatic and H-bonding interactions of CuNCs with BSA and Lys. The feasibility of strong metallophic interaction between the Fe2+ present in the heme group of Hb and Cu(I) or -S atoms present in the CuNCs brings considerable changes in the photophysical activity of CuNCs and their interactions with Hb. The functional groups on NCs as well as active amino acid residues present in proteins play a crucial role in determining their interactions. This work shed a piece of knowledge on designing NCs for specific biological applications.

A highly selective fluorescent sensor for chlortetracycline based on histidine-templated copper nanoclusters

In this study, histidine-protected copper nanoclusters (Cu NCs@His) were established by using a one-pot method, which histidine and ascorbic acid were applied as the template and reducing agent, respectively. The as-developed Cu NCs@His endued green emission wavelength at 494 nm with the excitation of 378 nm. The Cu NCs@His exhibited green fluorescence under UV light (365 nm). Using Cu NCs@His as a pattern nanosensor, the fluorescent "turn off" mechanism was fabricated for the determination of chlortetracycline in the light of the linear decrease of fluorescence intensities around 494 nm. The chlortetracycline conducted as a quencher, leading to reveal an excellent linear relationship between ln(F₀/F) of Cu NCs@His and chlortetracycline concentrations with the range of 0.5-200 μM, and the detection limit was 0.876 μM. The fluorescence quenching of Cu NCs@His revealed excellent selectivity for chlortetracycline over other potential interfering substances in the human body. This strategy was exhibited to be a convenient sensing platform for the detection of chlortetracycline in real medical samples, which could unfold a brand new and direct system for the sensing of chlortetracycline in real samples.