Fawei Zhu

Bio: Fawei Zhu is an academic researcher from Central South University. The author has contributed to research in topics: Fluorescence & Chemistry. The author has an hindex of 9, co-authored 20 publications receiving 307 citations.

A reusable P, N-doped carbon quantum dot fluorescent sensor for cobalt ion

Abstract: In this work, phosphorus, nitrogen co-doped carbon quantum dots (P,N-CQDs) as highly selective fluorescent probe for cobalt ion (Co2+) detection were designed and synthesized via a one-step hydrothermal protocol by employing pyridoxal 5-phosphate and ethanediamine. This probe enables selective detection of Co2+ with a linear range of 0–60 μM and a limit of detection of 0.053 μM through variation in fluorescence with respect to target concentration and electron-transfer from P,N-CQDs to Co2+. Furthermore, ethylenediaminetetraacetic acid-modified Fe3O4@SiO2 (Fe3O4@SiO2-EDTA) was tailor-designed and prepared to successfully realize the recovery of P,N-CQDs/Co2+ fluorescence for the first time. The reusable P,N-CQDs as fluorescent sensors for Co2+ also show good linearity and sensitivity. Ultimately, this fluorescent probe was applied in the analysis of real river water samples.

Integrating Target-Triggered Aptamer-Capped HRP@Metal-Organic Frameworks with a Colorimeter Readout for On-Site Sensitive Detection of Antibiotics.

Abstract: Colorimetric analytical strategies exhibit great promise in developing on-site detection methods for antibiotics, while substantial recent research efforts remain problematic due to dissatisfactory sensitivity. Taking this into account, we develop a novel colorimetric sensor for in-field detection of antibiotics by using aptamer (Apt)-capped and horseradish peroxidise (HRP)-embedded zeolitic metal azolate framework-7 (MAF-7) (Apt/HRP@MAF-7) as target recognition and signal transduction, respectively. With the substrate 3,3',5,5'-tetramethylbenzidine (TMB)-impregnated chip attached on the lid, the assay can be conveniently operated in a tube and reliably quantified by a handheld colorimeter. Hydrophilic MAF-7 can not only prevent HRP aggregation but also enhance HRP activity, which would benefit its detection sensitivity. Besides, the catalytic activity of HRP@MAF-7 can be sealed through assembling with Apt and controllably released based on the bioresponsivity via forming target-Apt complexes. Consequently, a significant color signal can be observed owing to the oxidation of colorless TMB to its blue-green oxidized form oxTMB. As a proof-of-concept, portable detection of streptomycin was favorably achieved with excellent sensitivity, which is superior to most reported methods and commercial kits. The developed strategy affords a new design pattern for developing on-site antibiotics assays and immensely extends the application of enzyme embedded metal-organic framework composites.

AIE-active metal–organic frameworks: facile preparation, tunable light emission, ultrasensitive sensing of copper(II) and visual fluorescence detection of glucose

Abstract: By binding aggregation-induced emission luminogens (AIEgens) with nanoscale ZIF-8, a series of novel luminescent metal–organic frameworks (LMOFs) with good photostability and excellent dispersibility have been facilely fabricated. The developed AIE-active MOFs not only inherit the intriguing AIE properties of AIEgens, including excited-state intramolecular proton transfer (ESIPT) properties, intense solid-state luminescence and large Stokes shifts (115–202 nm), but also show surprisingly boosted fluorescent emission efficiency (over 16 times) when compared with the original fluorescence of AIEgens. Meanwhile, the emission of AIE-active MOFs could also be finely engineered by varying the substituents on AIEgens. And as a proof of concept, the selected AIE-active MOF-2 (LMOF-2) served as a novel fluorescent probe for detecting copper ions (Cu2+), and a considerable response range (1–100 nM) and a sensitive picomolar detection limit (550 pM) were favorably obtained. More importantly, based on a glucose oxidase (GOD) catalyzed cascade redox reaction of LMOF-2/GOD nanocomposites, a fluorescent allochroic test strip was favourably developed for visual detection of glucose within a normal concentration range of fasting blood-glucose in human sera (3–8 mM), and has great potential to be applied in on-site assay of glucose in real serum samples due to its praiseworthy specificity and selectivity.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Abstract: We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Principles, mechanisms, and application of carbon quantum dots in sensors: a review

Abstract: Carbon quantum dots (CQDs) as an emerging class of quantum dots (QDs) with advantages such as good photoluminescence (PL) properties, easy synthesis routes, economical synthesis, cheap starting materials, water-solubility, low levels of toxicity, chemical stability, and easy functionalization have received great attention during recent years. CQDs have been used in versatile sensor applications. CQD sensors could be ultimately sensitive, and the limit of detection (LOD) for these sensors can reach the nanomolar, picomolar or even femtomolar ranges. CQD-based sensors and biosensors work with different mechanisms including fluorescence quenching, static quenching, dynamic quenching, energy transfer, inner filter effect (IFE), photo-induced electron transfer (PET), and fluorescence resonance energy transfer (FRET). CQD-based sensors and biosensors have been applied for the detection of different species such as metal ions, acids, proteins, biothiols, polypeptides, DNA and miRNA, water pollutants, hematin, drugs, vitamins, and other chemicals. It seems that CQD-based sensors and biosensors are promising candidates for high performance and yet accurate sensors in different areas. In this review, CQDs are introduced, and the synthesis methods and optical properties of CQDs are discussed. Different types of CQD-based sensors and biosensors and their working mechanisms are clarified.

Recent Developments in Two-Dimensional Liquid Chromatography: Fundamental Improvements for Practical Applications.

Abstract: Liquid chromatography (LC) is an incredibly successful analytical separation tool. Its versatility is unprecedented, because of the many different separation modes (reversed-phase LC, ion-exchange chromatography, size-exclusion chromatography, etc.) and because almost all samples can be dissolved in some kind of solvent, ranging from water to organic solvents to strong acids or bases. Conditions (mobile and stationary phases, additives, pH, temperatures, etc.) can be found to separate almost all pairs of analytes. For example, LC is immensely successful in the separation of enantiomers. Good selectivities can be accompanied by high efficiencies in a very short time, using contemporary ultra-high-performance liquid chromatography (UHPLC) instrumentation and (short) columns packed with sub-2-μm particles. However, LC cannot deliver very high efficiencies in a short time. Unlike other techniques, such as gas chromatography (GC) or capillary electrophoresis (CE), plate counts exceeding 100,000 are not routinely obtained in LC. As a result, LC cannot easily deal with complex mixtures that contain more than a few dozen analytes. While the selectivity between any pair of analytes can be maximized, these peaks may then start to overlap with other relevant analytes or with matrix compounds. There simply is not enough room in LC chromatograms to separate very many compounds that behave \"statistically\"1 and the attainable peak capacity does not suffice to separate complex samples. As a rule of thumb, LC offers a high probability of success for separating samples containing 10 or 20 components in 1 or 2 hours, or up to 50 components in about 10 hours2,3.