Copper nanocluster‐based fluorescence enhanced determination of d ‐penicillamine

Enhanced glutathione sensing in clinical samples with Bovine Serum Albumin-stabilized copper nanoclusters: A novel fluorescent probe

Glutathione (GSH) is a critical biomolecule involved in maintaining protecting against both oxidative stress and cellular redox homeostasis, making its accurate detection essential for clinical diagnostics. This study introduces a novel, highly sensitive, and selective fluorescence-based method for detecting GSH in human serum samples, using copper nanoclusters stabilised with Bovine Serum Albumin (BSA-CuNCs) as a probe. The BSA-CuNCs display a distinct fluorescence emission peak at 402 nm when excited at 326 nm, demonstrating exceptional photostability and structural integrity. The interaction with GSH not only significantly enhances the fluorescence intensity but also induces a red shift in the emission peak, attributed to the chemisorption of GSH onto the BSA-CuNCs surface, as confirmed by IR, TEM, and EDS analyses. This method achieves a broad linear detection range spanning from 2.95 to 207 µM and a highly sensitive detection limit of 79 nM, outperforming many existing detection techniques with respect to both selectivity and sensitivity. The BSA-CuNCs probe has been effectively used to measure the amount of GSH in human serum, with recovery values between 95.07 % and 101.38 %. Furthermore, the experimental results have been confirmed by density functional theory (DFT) calculations and molecular docking, yielding a full comprehension of the interaction mechanisms at the molecular scale. The novelty of this approach lies in its combination of high selectivity, sensitivity, and biocompatibility, making it a valuable tool for the early monitoring and diagnosis of diseases related to oxidative stress, such as cancer and neurodegenerative disorders. The method's simplicity, cost-effectiveness, and potential for adaptation to other biological targets underscore its significance.

Nitrogen-doped Ti3C2 MXene quantum dots as an effective FRET ratio fluorometric probe for sensitive detection of Cu2+ and D-PA

In this work, a ratiometric fluorescence sensing platform was established to detect Cu²⁺ and D-PA (d-penicillamine) based on nitrogen-doped Ti₃C₂ MXene quantum dots (N-MODs) that was prepared via a simple hydrothermal method and exhibited strong fluorescent and photoluminescence performance as well as excellent stability. Since the oxidation reaction between o-phenylenediamine (OPD) and Cu²⁺ induced the formation of 2,3-diaminophenazine (ox-OPD) which not only can emerge an emission peak at 570 nm, but also inhibit the fluorescence intensity of N-MQDs at 450 nm, a ratiometric reverse fluorescence sensor via fluorescence resonance energy transfer (FRET) was designed to sensitively detect Cu²⁺, where N-MQDs acted as energy donor and ox-OPD as energy acceptor. More importantly, another considerably interesting phenomenon was that their catalytic oxidation reaction can be restrained in the presence of D-PA because of the coordination of Cu²⁺ with D-PA, further triggering the obvious changes in ratio fluorescent signal and color, thus a ratiometric fluorescent sensor of determining D-PA was proposed also in this work. After optimizing various conditions, the ratiometric sensing platform showed rather low detection limits for Cu²⁺ (3.0 nM) and D-PA (0.115 μM), coupled with excellent sensitivity and stability.

Design of a dual-signal sensing platform for d-penicillamine based on UiO-66-NH2 MOFs and APBA@Alizarin Red

Herein, we designed a diversified sensing platform for d-penicillamine based on amino-functionalized Zr-based metal-organic frameworks (UiO-66-NH₂ MOFs) and 3-aminophenylboronic acid (APBA)@Alizarin Red (ARS). The boronic acid group of 3-aminophenylboronic acid could react with Alizarin Red to form an APBA@ARS complex with a yellow fluorescence emission at 580 nm and ultraviolet absorption at 435 nm. APBA@ARS can greatly quench the fluorescence of UiO-66-NH₂ MOFs at 450 nm via fluorescence resonance energy transfer (FRET). When copper ions were present in the reaction system of APBA and Alizarin Red, the copper ions could complex with Alizarin Red to prevent the generation of APBA@ARS, and the absorption of Cu@ARS at 530 nm occurred. Thus, the absorbance of APBA@ARS at 435 nm declined, restoring the fluorescence of UiO-66-NH₂ MOFs. Nevertheless, when d-penicillamine and copper ions coexist in the APBA and Alizarin Red reaction system, the copper ions would complex with the sulfhydryl group of d-penicillamine and no longer hinder the generation of APBA@ARS, and the fluorescence of UiO-66-NH₂ MOFs is quenched again. Meanwhile, the absorbance of APBA@ARS at 435 nm enhanced and the absorbance at 530 nm decreased. Thus, a fluorescence and colorimetric dual-signal sensing platform was constructed for d-penicillamine detection, which could detect d-penicillamine in the 1-20 μM and 2-50 μM ranges with the limit of detection (LOD) values of 0.46 μM and 1.38 μM, respectively. Furthermore, this sensing platform could also realize the intelligent RGB detection via mobile phones due to the obvious color change of the reaction system.

Fluorescent DNA-templated silver nanoclusters for highly sensitive detection of D-penicillamine

Herein, fluorescent DNA-templated silver nanoclusters (DNA-AgNCs) with red emission were synthesized and utilized as novel probe to detect D-penicillamine (D-Pen) for the first time. D-Pen molecules contain a thiol which can combine with Ag to form a non-fluorescent ground state complex, inducing the aggregation of DNA-AgNCs followed by the fluorescence quenching. The quenching mechanism is well-studied and found to be a static quenching process. This method can detect D-Pen in the range of 0.025-0.7 μM with the detection limit as low as 8 nM, which is 1-3 orders of magnitude more sensitive than those based on other fluorescent nanoprobes. More importantly, the preparation procedure for DNA-AgNCs is fast and without the requirement of heavy metal ions. Thus, this detection strategy is time-saving and eco-friendly. Satisfactory recoveries have been acquired for monitoring D-Pen in human serum samples and pharmaceutical samples owing to the high sensitivity.

Copper nanoclusters: designed synthesis, structural diversity, and multiplatform applications

Atomically precise metal nanoclusters (MNCs) have gained tremendous research interest in recent years due to their extraordinary properties. The molecular-like properties that originate from the quantized electronic states provide novel opportunities for the construction of unique nanomaterials possessing rich molecular-like absorption, luminescence, and magnetic properties. The field of monolayer-protected metal nanoclusters, especially copper, with well-defined molecular structures and compositions, is relatively new, about two to three decades old. Nevertheless, the massive progress in the field illustrates the importance of such nanoobjects as promising materials for various applications. In this respect, nanocluster-based catalysts have become very popular, showing high efficiencies and activities for the catalytic conversion of chemical compounds. Biomedical applications of clusters are an active research field aimed at finding better fluorescent contrast agents, therapeutic pharmaceuticals for the treatment and prevention of diseases, the early diagnosis of cancers and other potent diseases, especially at early stages. A huge library of structures and the compositions of copper nanoclusters (CuNCs) with atomic precisions have already been discovered during last few decades; however, there are many concerns to be addressed and questions to be answered. Hopefully, in future, with the combined efforts of material scientists, inorganic chemists, and computational scientists, a thorough understanding of the unique molecular-like properties of metal nanoclusters will be achieved. This, on the other hand, will allow the interdisciplinary researchers to design novel catalysts, biosensors, or therapeutic agents using highly structured, atomically precise, and stable CuNCs. Thus, we hope this review will guide the reader through the field of CuNCs, while discussing the main achievements and improvements, along with challenges and drawbacks that one needs to face and overcome.

A graphene quantum dots-Pb2+ based fluorescent switch for selective and sensitive determination of D-penicillamine

Taking consideration of metal-induced fluorescence quenching and excellent coordination effect of D-penicillamine (D-PA), a graphene quantum dots (GQDs)-based fluorescent switch for D-PA detection was designed and established firstly with the help of lead ions. GQDs obtained from citric acids made them rich in carboxyl and hydroxyl groups, giving GQDs the ability to combine with lead ions. As anticipated, the fluorescence intensity was quenched by Pb²⁺ through electron transfer process. Further, the addition of D-PA effectively recovered the fluorescence due to the departure of Pb²⁺ from GQDs aroused by the strong coordination between D-PA and Pb²⁺. Thus, a fluorescent switch was activated for D-PA detection. The fluorescence recovery efficiencies were found to be proportional to the concentration of D-PA in the range of 0.6-50 μmol L^-1 and the detection limit was 0.47 μmol L^-1. The real sample detection was performed in human urea sample and satisfactory recoveries of 96.84%-102.13% were obtained. The GQDs-Pb²⁺ based fluorescent switch sensing method was firstly established with low detection limit and wide linear range, making it a supplement and improvement for D-PA detection.