Zhaona Liu

Highly sensitive and selective electrochemical detection of L-cysteine using nanoporous gold

AbstractNanoporous gold (NPG) with uniform pore sizes and ligaments was prepared by using a simple dealloying method. NPG electrodes exhibit excellent electrocatalytic activity towards the oxidation of CySH and the mechanism for the electrochemical reaction of CySH on NPG has been discussed. Interestingly, if the operating potential is fixed at 0.65 V, a strong current is observed and interferences by tryptophan and tyrosine are avoided. The calibration plot is linear in the concentration range from 1 μM to 400 μM (R2 = 0.994), and the quantification limit is as low as 50 nM. The NPG-modified electrode has good reproducibility, high sensitivity and selectivity, can be used to sense CySH in aqueous solution. FigureNanoporous gold with uniform pore sizes and ligaments was employed as sensitive and selective electrochemical sensor for detection of Lcysteine, and the quantification limit is as low as 50 nM.

Multi-responsive cyclodextrin vesicles assembled by ‘supramolecular bola-amphiphiles’

Multi-responsive cyclodextrin vesicles (CDVs) self-assembled by ‘supramolecular bola-amphiphiles’, consisting of a guest (N,N′-bis(ferrocenylmethylene)-diaminohexane, 1) and a host (γ-hydroxybutyric-β-cyclodextrin, γ-HB-β-CD), were prepared and investigated for the first time. The morphologies and sizes of these novel vesicles in water were observed by transmission electron microscopy (TEM), scanning electron microscopy and dynamic light scattering. The effects of the host–guest ratio, the concentration and the solvent composition are also discussed. The host–guest interactions, complex stoichiometry and structures of 1·γ-HB-β-CD in water were investigated by cyclic voltammetry, UV and NMR spectroscopy. According to the complex stoichiometry, TEM observations and Chem3D estimation, the ‘supramolecular bola-amphiphiles’, made from 1·γ-HB-β-CD and assumed for the first time, formed the membranes of the CDVs. The CDV system was responsive to an oxidising agent, which is the first report on redox-responsive systems in this field. The CDVs are also responsive to pH and the presence of metal ions, such that they disassemble upon addition of acetic acid or Cu2+ ions, providing possible routes to drug delivery systems.

Fluorescent Vesicular Particles Assembled by Inclusion Complexes Between Cyclodextrins and BPB

Vesicular particles based on inclusion complexes between BPB and γ-HB-β-CDs were prepared and characterized for the first time. The morphologies and sizes were confirmed by transmission electron microscopy (TEM), scanning electron microscope (SEM), and dynamic light scattering (DLS). Particularly, these vesicular particles exhibiting clearly fluorescent dots observed by laser confocal scanning microscopy (LCSM) could be alternative candidates as fluorescent probes and labels being applied to cellular staining, labeling, bio-mimicking and drug delivery. The ultraviolet, fluorescence, and nuclear magnetic resonance (NMR) measurements confirmed the existence of stable 1:1 BPB-γ-HB-β-CD complexes in the system. The vesicular particles were assumed to be constructed by orderly self-aggregates of these inclusion complexes.