Linhong Deng

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.

pH-Controlled drug delivery with hybrid aerogel of chitosan, carboxymethyl cellulose and graphene oxide as the carrier

Hybrid aerogels of chitosan (CS), carboxymethyl cellulose (CMC) and graphene oxide (GO) are successfully prepared by using calcium ion (Ca2+) as the crosslinker. The resultant hybrid aerogels, CS/CMC/Ca2+/GO, are characterized by field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FT-IR) spectroscopy. Due to the pH sensitivity of CS and CMC, pH-controlled drug delivery with CS/CMC/Ca2+/GO as the carrier is investigated using 5-fluorouracil (5-FU), an effective chemotherapeutic agent in the treatment of cancers, as the model drug. Finally, Higuchi model and Korsmeyer-Peppas model are used to study the release kinetics, and it reveals that the release of 5-FU from the hybrid aerogels is controlled by Fickian diffusion. Collectively, the findings demonstrate the CS/CMC/Ca2+/GO would be a potential material for the construction of pH-controlled drug delivery platform.

Overoxidation and Camphorsulfonic Acid Coinduced Chiral Microenvironment in Polypyrrole for Electrochemical Chiral Sensing

Polypyrrole (PPy) was synthesized by a galvanostatic method using (1 S)-(+)-10-camphorsulfonic acid ((+)-CSA) as the dopant, and the produced PPy was further overoxidized in a solution of (+)-CSA. A chiral microenvironment was successfully formed in the overoxidized PPy (OPPy) as a result of the synergistic effects of overoxidation and (+)-CSA, resulting in a twisted helical architecture of the OPPy chains. The formation of optically active OPPy was confirmed from aspects of its morphology (SEM and AFM) and circular-dichroism (CD) spectra. Finally, an electrochemical chirality sensor was fabricated on the basis of the resultant OPPy, which exhibited excellent biomolecular homochirality in the discrimination of tryptophan (Trp) enantiomers.

A Facile Route to Prepare Functional Mesoporous Organosilica Spheres with Electroactive Units for Chiral Recognition of Amino Acids

Conductive materials are valuable supports and widely applied in electrochemical analysis. In the current article, a mesoporous organosilica sphere (S,S)-CPMO-3 with the chiral group and electroactive units is presented. The organosilicon framework is composed of free ions belonging to the ionic liquid and the chiral group arising from (1S,2S)-1,2-diaminocyclohexane. Next, a bare electrode was modified by the as-synthesized composite material to construct the new electrochemical sensor (S,S)-CPMO-3-GCE. It was observed that (S,S)-CPMO-3-GCE exhibited favourable enantioselective recognition in the response of the peak current (Ip) and the peak potential (Ep) to the different configurations of amino acids. Taking tryptophan as an example, the value of IL/ID is 13.84 and the peak-to-peak potential approaches 48 mV. In addition, cysteine and tyrosine were successfully distinguished by the sensor. In summary, this study not only introduces a route for the synthesis of a conductive material, but also opens up its further potential in enantioselective recognition.