Yongxin Tao

Crosslinking Graphene Oxide into Robust 3D Porous N‐Doped Graphene

3D N-doped graphene crosslinked by covalent bonds is fabricated through thermal treatment of graphene oxide with a nitrogen-contained resin. The material possesses a hierarchical porous architecture, robust mechanical stability, and abundant N-doped properties. As an electrode material for supercapacitors, this multifunctional material exhibits an unprecedented specific capacitance, high rate capability, and excellent long-term cycle stability.

In situ synthesis of highly loaded and ultrafine Pd nanoparticles-decorated graphene oxide for glucose biosensor application

Highly loaded and ultrafine Pd nanoparticles were supported on graphene oxide (PdNPs-GO) via an in situ, simple and clean strategy on the basis of the direct redox reaction between Pd(OAc)2 and GO. A highly sensitive biosensor was developed for the detection of glucose based on the electrode modified with PdNPs-electrochemically reduced GO (PdNPs-ERGO). The glucose biosensor shows a wide linear range, low detection limit, good reproducibility and acceptable stability, providing a biocompatible platform for biosensing and biocatalysis.

DNA-inspired electrochemical recognition of tryptophan isomers by electrodeposited chitosan and sulfonated chitosan.

Inspired by the double helix structure of DNA, a simple enantioselective system based on chitosan (CS) was employed for electrochemical enantiorecognition of tryptophan (Trp) isomers. The recognition mechanism was proposed from the supramolecular point of view, which was further verified by the recognition of Trp isomers with sulfonated CS (SCS). The SCS-based chiral system presented the ability of indicating the percentage of d-Trp in racemic mixture, extending future applications of the electrochemical chiral system based on natural polysaccharides.

Highly fluorescent and morphology-controllable graphene quantum dots-chitosan hybrid xerogels for in vivo imaging and pH-sensitive drug carrier

Highly fluorescent graphene quantum dots (GQDs)-chitosan (CS) hybrid xerogels (GQDs-CS) were facilely synthesized, and the morphology of GQDs-CS was controllable by varying the content of GQDs in the xerogel. The GQDs-CS exhibited a porous and three-dimensional (3D) network structure when the content of GQDs reached 43% (wt%) in the xerogel, which was beneficial for drug loading and sustained release. The as-prepared GQDs-CS could also be applied for in vivo imaging since it showed strong blue, green and red luminescence under excitation of varying wavelengths. Moreover, the pH-induced protonation/deprotonation of the -NH2 groups on CS chains can result in a pH-dependent drug delivery behavior of the GQDs-CS hybrid xerogel.

Rationally Designed 3D Fe and N Codoped Graphene with Superior Electrocatalytic Activity toward Oxygen Reduction

Pyrolyzing Fe- and N-contained precursor together or separately with graphene results in codoped graphene dominated by bonded or separated Fe and N configuration, respectively. While the FeN bonded case greatly enhances activity toward oxygen reduction, the separated one does not. This rationally designed Fe and N codoped 3D graphene exhibits superior electrocatalytic activity than the state-of-the-art Pt/C catalyst.

Nonenzymatic glucose sensing by CuO nanoparticles decorated nitrogen-doped graphene aerogel

CuO nanoparticles decorated N-doped graphene aerogel (NGA-CuO) was facilely synthesized via a mild hydrothermal method followed by freeze-drying and calcination, which was characterized by TEM, FT-IR, XPS, XRD and electrochemical impedance spectroscopy (EIS). The obtained NGA-CuO was used for the construction of a nonenzymatic sensing platform for glucose, exhibiting wide linear range, low detection limit, high sensitivity, reproducibility, selectivity and stability. The excellent analytical performances of the NGA-CuO based glucose sensor might be attributed to the synergistic effect of CuO nanoparticles and N-doped graphene aerogel (NGA). The practical applications of the proposed sensor was verified by determining glucose concentrations in five human serum samples, and the obtained results were quite comparable to those measured on the standard clinical instrument.

Synthesis of porous starch xerogels modified with mercaptosuccinic acid to remove hazardous gardenia yellow

Mercaptosuccinic acid (MSA) molecules were inserted into potato starch, leading to the breaking of intrinsic H-bonds within macromolecular chains of starch and the formation of intermolecular H-bonds between MSA and starch, which could be verified by Fourier transform infrared spectroscopy (FT-TR). MSA modified porous starch xerogels (PSX/MSA) were obtained after freeze-drying the MSA modified starch, and they were characterized by field emission scanning electron microscopy (FESEM), exhibiting the intriguing porous structure due to the separation of starch chains by MSA molecules. The PSX/MSA were then used as the adsorbents to remove gardenia yellow (GY), a natural colorant with genotoxicity. Due to the porous structure of PSX and the introduced carboxyl groups from MSA, the adsorption capacity of the PSX/MSA was much higher than that of the starch xerogels alone (SX). The adsorption behaviors of GY by the PSX/MSA fitted both the Freundlich isotherm model and the pseudo-second-order kinetic model, and the efficient adsorption of GY suggested that the PSX/MSA might be potential adsorbents for the removal of dyes from contaminated aquatic systems.

An efficient chiral sensing platform based on graphene quantum dot–tartaric acid hybrids

Graphene quantum dots (GQDs) and tartaric acid (TA) were successively electrodeposited onto the surface of a glassy carbon electrode (GCE). Due to the intrinsic chirality of L-(+)-TA and D-(−)-TA and the signal amplification function of GQDs, the GQDs–TA hybrid modified GCE could be regarded as an efficient electrochemical chiral sensing platform and used for chiral recognition of tryptophan (Trp) isomers. The recognition efficiency with the proposed GQDs–TA is significantly higher than that with TA alone. Of particular interest, GQDs-L-(+)–TA and GQDs-D-(−)–TA exhibit completely opposite selectivity toward L-Trp and D-Trp. Also in this work, the pH-sensitive enantiorecognition of the GQDs–TA hybrids was investigated.

The electrocatalytic characteristics of poly(azure B) and its application in the sensitive determination of hydroquinone

Poly(azure B) (PAB) electropolymerized on a glassy carbon electrode (GCE) can effectively catalyze the oxidation and reduction of hydroquinone (HQ), with PAB acting as an electron transfer mediator. Compared with a bare GCE, the PAB-modified GCE significantly enhances the peak current and reduces the oxidation peak potential of HQ. The current of HQ on the PAB-modified GCE is proportional to its concentration, and thus provides an efficient approach for the determination of HQ. Under optimal conditions, the PAB-modified GCE displays a linear response for 8 to 4000 μM HQ, and the detection limit is 4.8 μM (S/N = 3). Moreover, it was found that catechol, an important isomer of HQ, does not interfere in the determination of HQ using the PAB-modified GCE.

Core-shell structured polypyrrole/mesoporous SiO2 nanocomposite capped with graphene quantum dots as gatekeeper for irradiation-controlled release of methotrexate

A core-shell structured nanocomposite of polypyrrole/mesoporous SiO2 (PPy/mSiO2) is rationally designed as the nanocarrier for methotrexate (MTX), a chemotherapeutic drug for cancer treatment. Graphene quantum dots (GQDs) are introduced to the outer surface of PPy/mSiO2, and it functions as a gatekeeper for the loaded MTX through the formation of H-bonds with the functionalized mSiO2. In the proposed nanocarrier for MTX, the mesopores in mSiO2 are beneficial for the accommodation of MTX, resulting in enhanced encapsulation capacity of the nanocarrier; on the other hand, PPy can effectively convert the near-infrared (NIR) light to heat. Under the irradiation of NIR light, the H-bonds between GQDs and mSiO2 are broken due to the gradually increased temperature, and therefore the GQDs cap is removed and consequently the encapsulated MTX is released from the nanocarrier. In this study, NIR irradiation-controlled drug delivery is achieved successfully owing to the synergistic effects of PPy, mSiO2 and GQDs, which opens a new window for the construction of smart drug delivery systems.