Rapid synthesis of fluorescent bovine serum albumin-gold nanoclusters complex for glutathione determination

Horseradish peroxidase-catalyzed polyacrylamide gels: monitoring their polymerization with BSA-stabilized gold nanoclusters and their functional validation in electrophoresis

Polyacrylamide gel (PAG) is extensively used as a matrix for biomolecular analysis and fractionation. However, the traditional polymerization catalyst system N,N,N',N'-tetramethylethylenediamine (TEMED)/ammonium persulphate (APS) of PAG presents non-negligible toxicity. Herein, we utilized the green and efficient bio-enzyme horseradish peroxidase (HRP) to catalyze the gel polymerization of polyacrylamide. At the same time, the efficacy of this gel system in separating nucleic acids and proteins was confirmed by applying the gel system in electrophoresis. This study aims to explore a higher biosafety polyacrylamide gel polymerization catalytic system which can be applied to electrophoresis technology. Furthermore, in order to differentiate between the bio-enzymatic catalytic system and the traditional toxic catalytic system during polymerization, aggregation-induced luminescence (AIE) of bovine serum albumin-stabilized gold nanoclusters (BSA-Au NCs) was used to monitor the polymerization reaction of the system. The results indicated that the fluorescence intensity of the polymeric system containing BSA-Au NCs increased with the polymerization of the monomers. Subsequently, we assessed whether certain components of nucleic acid electrophoresis and protein electrophoresis such as sodiumdodecylsulfate (SDS) and TBE buffer (Tris-boric acid, EDTA, pH 8.3) would affect the polymerization of the polyacrylamide gels catalyzed by the biological enzymes. The experimental conditions were also optimized to explore the optimal concentration of the ternary system of HRP, H2O2 and ACAC. Our results suggested that the bioenzyme-catalyzed system could be a feasible alternative to the TEMED/APS-catalyzed system, which also could provide new insights into the methods of monitoring the polymerization system.

Dual ligand-capped gold nanoclusters for the smart detection of specific reactive oxygen species

Quantitative detection of different types of reactive oxygen species (ROS) is vital for understanding the crucial roles of them in biological processes. However, few researches achieved the detection of multiple types of ROS with one probe until now. Given this, we designed and prepared fluorescent gold nanoclusters capped by dual ligand bovine serum albumin and lysozyme (BSA-LYS-AuNCs), which could detect 3 specific types of ROS based on its different fluorescent responses to H₂O₂, •OH and ClO^-, respectively. The limit of detection (LOD) of H₂O₂, •OH, and ClO^- was as low as 0.82 μM, 0.45 μM, and 0.62 μM. Moreover, as an important ROS type, ClO^- was detected with high sensitivity and low LOD by BSA-LYS-AuNCs. It was also proved that the crosslinking of protein mainly contributed to the unique fluorescent characteristics of the probe exposing to ClO^-. Furthermore, the fluorescent probe achieved the smart detection of hROS (including •OH and ClO^-) and wROS (the form of H₂O₂) in the real sample, which could also been applied specifically to the detection of antioxidants, e.g. ascorbic acid. The gold nanoclusters developed have high potential for the smart detection of multiple ROS in the body fluid of organisms.

Metal Complexes in Target-Specific Anticancer Therapy: Recent Trends and Challenges

Cancer is characterized by abnormal cell differentiation in or on the part of the body. The most commonly used chemotherapeutic drugs are developed to target rapidly dividing cells, such as cancer cells, but they also damage healthy epithelial cells. This has serious consequences for normal cells and become responsible for the development of various disorders. Several strategies for delivering the cytotoxic drugs to cancerous sites that limit systemic toxicity and other adverse effects have recently been evolved. Among them, biomolecule-conjugated metal complexes-based cancer targeting strategies have shown tremendous advantages in cancer therapy. This review focuses on several chemoselective biomolecules-bound metal complexes as prospective cancer therapy-targeted agents. In this review, we presented the details of the various extra- and intracellular targeting mechanisms in cancer therapy. We also addressed the current clinical issues and recent therapeutic strategies in targeted cancer therapy that may pave a way for the future direction of metal complexes-based targeted cancer therapy.

Turn-on signal fluorescence sensor based on DNA derived bio-dots/polydopamine nanoparticles for the detection of glutathione

A convenient, fast, sensitive and highly selective fluorescence sensor for the detection of glutathione (GSH) based on DNA derived bio-dots (DNA bio-dots)/polydopamine (PDA) nanoparticles was constructed. The fluorescent switch of DNA bio-dots was induced to turn off because of fluorescence resonance energy transfer (FRET) reactions between DNA bio-dots and PDA. The presence of GSH blocked the spontaneous oxidative polymerization of dopamine (DA) to PDA, leading the fluorescent switch of DNA bio-dots to be "turned on". The degree of fluorescence recovery of DNA bio-dots is linearly correlated with the concentration of GSH within the range of 1.00-100 μmol L-1, and the limit of detection (LOD) is 0.31 μmol L-1 (S/N = 3, n = 9). Furthermore, the fluorescence sensor was successfully used to quantify GSH in human urine and glutathione whitening power, indicating the fluorescence sensor has potential in the detection of human body fluids and pharmaceutical preparations.

A ratio fluorescence method based on dual emissive gold nanoclusters for detection of biomolecules and metal ions

Gold nanoclusters have good biocompatibility and can be easily modified to improve their luminescence properties. In this study, we prepared a new type of dual-emitting gold nanoclusters (d-Au NCs) for discriminative detection of phenylalanine and Fe³⁺ with high selectivity and sensitivity. The fluorescence sensor which was synthesized without any further assembly or conjugation shows dual-emissions at 430 nm and 600 nm under a single excitation at 350 nm. Phenylalanine can turn on the red emission of the probe, while Fe³⁺ can turn on its yellow emission and turn off the red emission. By detecting a variety of amino acids and metal ions, d-Au NCs showed good selectivity to phenylalanine and Fe³⁺. Finally, this method was applied to determine phenylalanine and Fe³⁺ in lake water, human urine and milk, which has certain application prospects in the field of biology and environment.

Novel dual-emissive gold nanoclusters (d-Au NCs) were prepared and applied for the simultaneous detection of phenylalanine or Fe³⁺.

In situ synthesis of chiral AuNCs with aggregation-induced emission using glutathione and ceria precursor nanosheets for glutathione biosensing

Au(i)–SG/Ce(CO3)2 NS conjugated nanoprobe was developed for selective GSH detection. The redox reaction between GSH and the NS could release Ce3+ ions to initiate the intense AIE of Au(i)–SG oligomers.