Ju Mei,†,‡,∥ Nelson L. C. Leung,†,‡,∥ Ryan T. K. Kwok,†,‡ Jacky W. Y. Lam,†,‡ and Ben Zhong Tang*,†,‡,§ †HKUST-Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China ‡Department of Chemistry, HKUST Jockey Club Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, State Key Laboratory of Molecular Neuroscience, Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China

Aggregation-Induced Emission: Together We Shine, United We Soar!

Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1–3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the s...

Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities

The emerging graphene quantum dots (GQDs) and carbon dots (C-dots) have gained tremendous attention for their enormous potentials for biomedical applications, owing to their unique and tunable photoluminescence properties, exceptional physicochemical properties, high photostability, biocompatibility, and small size. This article aims to update the latest results in this rapidly evolving field and to provide critical insights to inspire more exciting developments. We comparatively review the properties and synthesis methods of these carbon nanodots and place emphasis on their biological (both fundamental and theranostic) applications.

Glowing Graphene Quantum Dots and Carbon Dots: Properties, Syntheses, and Biological Applications

Because of the high catalytic activities and substrate specificity, natural enzymes have been widely used in industrial, medical, and biological fields, etc. Although promising, they often suffer from intrinsic shortcomings such as high cost, low operational stability, and difficulties of recycling. To overcome these shortcomings, researchers have been devoted to the exploration of artificial enzyme mimics for a long time. Since the discovery of ferromagnetic nanoparticles with intrinsic horseradish peroxidase-like activity in 2007, a large amount of studies on nanozymes have been constantly emerging in the next decade. Nanozymes are one kind of nanomaterials with enzymatic catalytic properties. Compared with natural enzymes, nanozymes have the advantages such as low cost, high stability and durability, which have been widely used in industrial, medical, and biological fields. A thorough understanding of the possible catalytic mechanisms will contribute to the development of novel and high-efficient nanozymes, and the rational regulations of the activities of nanozymes are of great significance. In this review, we systematically introduce the classification, catalytic mechanism, activity regulation as well as recent research progress of nanozymes in the field of biosensing, environmental protection, and disease treatments, etc. in the past years. We also propose the current challenges of nanozymes as well as their future research focus. We anticipate this review may be of significance for the field to understand the properties of nanozymes and the development of novel nanomaterials with enzyme mimicking activities.

Nanozymes: Classification, Catalytic Mechanisms, Activity Regulation, and Applications

A hydrothermal approach for the cutting of boron-doped graphene (BG) into boron-doped graphene quantum dots (BGQDs) has been proposed. Various characterizations reveal that the boron atoms have been successfully doped into graphene structures with the atomic percentage of 3.45%. The generation of boronic acid groups on the BGQDs surfaces facilitates their application as a new photoluminescence (PL) probe for label free glucose sensing. It is postulated that the reaction of the two cis-diol units in glucose with the two boronic acid groups on the BGQDs surfaces creates structurally rigid BGQDs–glucose aggregates, restricting the intramolecular rotations and thus resulting in a great boost in the PL intensity. The present unusual “aggregation-induced PL increasing” sensing process excludes any saccharide with only one cis-diol unit, as manifested by the high specificity of BGQDs for glucose over its close isomeric cousins fructose, galactose, and mannose. It is believed that the doping of boron can introduc...

Boron-Doped Graphene Quantum Dots for Selective Glucose Sensing Based on the “Abnormal” Aggregation-Induced Photoluminescence Enhancement

A simple and sensitive photoluminescence (PL) assay for the activity of a protein kinase based on the selective aggregation of phosphorylated peptide–graphene quantum dot (GQD) conjugates triggered by Zr4+ ion coordination has been established. With more sophisticated design of the peptide substrate sequences, detecting other enzymes could also be possible. Under optimal conditions, a linear relationship between the decreased PL intensity of peptide–GQD conjugates and the concentration of casein kinase II (CK2) in the range from 0.1 to 1.0 unit mL–1 with a detection limit of 0.03 unit mL–1 (3σ) was obtained. The EC50 value (i.e., the enzyme concentration producing 50% substrate conversion) for CK2 was evaluated to be 0.34 unit mL–1. The proposed method showed potential applications in kinase inhibitor screening. To demonstrate the potential of this GQD-based platform for screening of kinase inhibitors in real biological systems, the inhibition of CK2 phosphorylation activity by four different inhibitors (...

Using graphene quantum dots as photoluminescent probes for protein kinase sensing.

The sense of it: A new type of rapid, sensitive, and specific photoluminescence (PL)-based assay has been proposed for the detection of phosphate (Pi) based on the competition of oxygen-donor atoms from Pi with those from the carboxylate groups on a graphene-quantum-dot (GQD) surface for Eu(3+) ions. The graphene-like structures combined with QD-like optical properties suggest the promising nature of the GQDs as versatile tools in the fields of analytical science and biotechnology.

Graphene quantum dots combined with europium ions as photoluminescent probes for phosphate sensing.

Lanthanide coordination polymer nanoparticles (Ln-CPNs) have been recently demonstrated as excellent platforms for biomolecule detection. In this work, we synthesized novel cerium coordination polymer nanoparticles ATP-Ce-Tris CPNs in a simple and quick way using ATP molecules as the biocompatible ligands to Ce3+ ions in tris(hydroxymethyl)aminomethane hydrochloric (Tris-HCl) solution. In view of the excellent free radical scavenging property of cerium compounds, which is ascribed to the mixed valence state (Ce3+, Ce4+) and the reversible switch from Ce3+ to Ce4+, the synthesized ATP-Ce-Tris CPNs was used as artificial peroxidase to selectively and sensitively detect H2O2. The sensing mechanism depends on the oxidation of the fluorescent ATP-Ce(III)-Tris CPNs to nonfluorescent ATP-Ce(IV)-Tris CPNs by H2O2. Compared with those inorganic cerium oxide sensors, this kind of fluoresence ATP-Ce-Tris CPNs sensor needs no additional organic redox dye, such as ABTS (2,20-azino-bis(3-ethylbenzthiazoline-6-sulfonic ...

Lanthanide Coordination Polymer Nanoparticles as an Excellent Artificial Peroxidase for Hydrogen Peroxide Detection

Dry reforming of methane (DRM) is a fascinating reaction that utilizes two greenhouse gases (CH4 and CO2) to produce value-added synthesis gas (syngas, a mixture of CO and H2) or hydrogen as a green energy source. Ni-based nanomaterials are considered the most promising DRM catalysts used in industry. However, Ni-based catalysts have sintering and stability problems that need to be resolved. Herein, Ni nanoparticles (NPs) confined in mesopores of aluminum-modified SBA-15 (AlSBA-15) were prepared for the first time using ethylene glycol (EG) as the solvent and delivery conveyor (Ni/AlSBA-15-EG). Transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) results showed that ultra-small Ni NPs (average particle size, 3.1 nm) were successfully embedded into the hexagonal mesopores of AlSBA-15 with a perfect peasecod-like structure. Compared with Ni/SBA-15-EG, the Ni/AlSBA-15-EG catalyst exhibited better catalytic activity and coke resistance in DRM. To further test their hydrothermal stability under more harsh reaction conditions (the reverse water gas shift reaction takes place under DRM conditions), the catalysts were first tested in the methane steam reforming reaction. After testing for 20 h, the Ni/AlSBA-15-EG catalyst retained its original structure, while the mesopores of Ni/SBA-15-EG had totally collapsed. This clearly indicated that the Ni/AlSBA-15-EG catalyst had superior hydrothermal stability and potential for long-term use in the DRM reaction (in which the reverse water gas shift reaction is present). Therefore, the ultra-small Ni particle size, confinement effect deriving from the mesoporous channels of AlSBA-15 support, and superior hydrothermal stability (derived from Al-stabilized SBA-15) are proposed as the main factors contributing to the excellent performance of Ni/AlSBA-15-EG catalyst in methane reforming reactions. This strategy could be used to design other high-performance Ni-based catalysts for DRM.

Nickel nanoparticles embedded in mesopores of AlSBA-15 with a perfect peasecod-like structure: A catalyst with superior sintering resistance and hydrothermal stability for methane dry reforming

Li Zhang

Papers

Boron-Doped Graphene Quantum Dots for Selective Glucose Sensing Based on the “Abnormal” Aggregation-Induced Photoluminescence Enhancement

Using graphene quantum dots as photoluminescent probes for protein kinase sensing.

Graphene quantum dots combined with europium ions as photoluminescent probes for phosphate sensing.

Lanthanide Coordination Polymer Nanoparticles as an Excellent Artificial Peroxidase for Hydrogen Peroxide Detection

Nickel nanoparticles embedded in mesopores of AlSBA-15 with a perfect peasecod-like structure: A catalyst with superior sintering resistance and hydrothermal stability for methane dry reforming