Wei Ha

Stimuli-induced gel–sol transition of multi-sensitive supramolecular β-cyclodextrin grafted alginate/ferrocene modified pluronic hydrogel

This paper studies a kind of biocompatible hydrogel composed of alginate-g-β-cyclodextrin (Alg-β-CD) and ferrocene-terminated pluronic F127 (F127-Fc), which showed gel–sol phase transformations in response to temperature, oxidizing agents, and glucose because of the reversible association–dissociation of Fc-β-CD inclusions and F127 micelles.

Supramolecular Hybrid Hydrogel Based on Host–Guest Interaction and Its Application in Drug Delivery

In this work, we developed a simple, novel method for constructing gold nanocomposite supramolecular hybrid hydrogels for drug delivery, in which gold nanocrystals were utilized as building blocks. First, methoxypoly(ethylene glycol) thiol (mPEG-SH, molecular weight (MW)=5 K) capped gold nanocrystals (nanospheres and nanorods) were prepared via a facile one-step ligand-exchange procedure. Then, the homogeneous supramolecular hybrid hydrogels were formed, after adding α-cyclodextrin (α-CD) into PEG-modified gold nanocrystal solutions, due to the host-guest inclusion. Both gold nanoparticles and inclusion complexes formed between α-CD and PEG chain provided the supra-cross-links, which are beneficial to the gelation formation. The resulting hybrid hydrogels were fully characterized by a combination of techniques including X-ray diffraction, rheology studies, and scanning electron microscopy. Meanwhile, the hybrid hydrogel systems demonstrated unique reversible gel-sol transition properties at a certain temperature caused by the temperature-responsive reversible supramolecular assembly. The drug delivery applications of such hybrid hydrogels were further investigated in which doxorubicin was selected as a model drug for in vitro release, cytotoxicity, and intracellular release studies. We believe that the development of such hybrid hydrogels will provide new and therapeutically useful means for medical applications.

Tunable Temperature-Responsive Supramolecular Hydrogels Formed by Prodrugs As a Codelivery System

Taking advantage of the strong hydrophobicity of the anticancer drug camptothecin (CPT), the CPT molecule was conjugated to a class of low-molecular-weight (MW) poly(ethylene glycol) (PEG) chains (MW = 500, 1000, and 2000), forming an amphiphilic prodrug. The CPT-PEG prodrug formed stable hydrogels based on a combination of the partial inclusion complexation between one end of the PEG blocks and α-CD and the hydrophobic aggregation of CPT groups. Meanwhile, the formed hydrogels could be loaded with water-soluble drug 5-fluorouracil (5-FU), which is always combined with CPT drugs to enhance their anticancer activity. Moreover, the hydrogel systems demonstrate unique structure-related reversible gel-sol transition properties at a certain temperature due to the reversible supramolecular assembly, and the gel-sol transition temperature could be modulated by varying the length of the PEG chain and the concentrations of α-CD, demonstrating the possibility of achieving on-demand gel-sol transitions. The structure-related reversible gel-sol transition properties were proved by rheological property, XRD, DSC, and SEM measurements. The different controlled release profiles of two different anticancer drugs showed significant temperature-dependent properties. This easily prepared supramolecular hydrogel with excellent biocompatibility and tunable temperature responsiveness has significant potential for controlled drug release applications.

Self-assembly hollow nanosphere for enzyme encapsulation

This paper studies a kind of self-assembled hollow nanosphere for L-asparaginase encapsulation, and it was found that the hollow spheres not only enable a high loading of enzyme, but also show semi-permeability which could prevent the enzyme from leaving while allowing substrates and products to pass through to maintain the enzyme activity, and the encapsulated L-asparaginase showed significantly higher stability.

Hollow Nanospheres Based on the Self-Assembly of Alginate-graft-poly(ethylene glycol) and α-Cyclodextrin

This article studies the self-assembly of alginate-graft-poly(ethylene glycol) (Alg-g-PEG) and α-cyclodextrin (α-CD) in aqueous solution. It was found that they could form hollow spheres because of the formation of coil-rod Alg-g-PEG/α-CD inclusion complexes. In these Alg-g-PEG/α-CD complexes, the α-CDs are stacked along the PEG side chains to form a rod block, and alginate main chains act as a coil block. More rod-like blocks in Alg-g-PEG/α-CD favor the formation of small assemblies. The assemblies of Alg-g-PEG/α-CD show a dependence on concentration, temperature, pH, and salt concentration. At low concentration (below 0.125%) or high temperature (above 32 °C), Alg-g-PEG/α-CD particles were unstable and disrupted. Increasing the salt or decreasing the pH resulted in the aggregation of Alg-g-mPEG/α-CD particles, as detected by the increase in the recorded hydrodynamic diameter (D(h)).

Self-assembly of β-cyclodextrin and pluronic into hollow nanospheres in aqueous solution

This paper studies self-assembly of beta-cyclodextrin (beta-CD) and tri-block pluronic (PEG-PPG-PEG) in aqueous solution. It was found that they could form hollow spheres due to the formation of coil-rod beta-CD/PEG-PPG-PEG inclusion complexes. In these beta-CD/PEG-PPG-PEG complexes, the beta-CDs are preferentially stacked along the PPG block of pluronic to form rod block and PEG segments act as coil block. The assemblies of beta-CD/PEG-PPG-PEG complexes show dependence of beta-CDs concentration and temperature. Furthermore, the aggregates will disrupt upon dilution below the critical micelle concentration.

Application of β-cyclodextrin-modified, carbon nanotube-reinforced hollow fiber to solid-phase microextraction of plant hormones.

A new, efficient, and environmental friendly solid-phase microextraction (SPME) medium based on β-cyclodextrin (β-CD)-modified carbon nanotubes (CNTs) and a hollow fiber (HF) was prepared. Functionalized β-CD was covalently linked to the surface of the carboxylic CNTs and then the obtained nanocomposite was immobilized into the wall pores of HFs under ultrasonic-assisted effect. The scanning electron microscope was used to inspect surface characteristics of fibers, demonstrating the presence of nanocomposites in their wall pores. The reinforced HF was employed in SPME, and its extraction performance was evaluated by analyzing 1-naphthaleneacetic acid (NAA) and 2-naphthoxyacetic acid (2-NOA) in vegetables. Without any tedious clean-up procedure, analytes were extracted from the sample to the adsorbent and organic solvent immobilized in HFs and then desorbed in acetonitrile prior to chromatographic analysis. Under the optimized extraction conditions, the method provided 275- and 283-fold enrichment factors of NAA and 2-NOA, low limits of detection and quantification (at an ngg(-1) level), satisfactory spiked recoveries, good inter-fiber repeatability, and batch-to-batch reproducibility. The selectivity of the developed fiber was investigated to three structurally similar compounds and two reference compounds with recognition coefficients up to 3.18. The obtained results indicate that the newly developed fiber is a feasible, selective, green, and cost-effective microextraction medium and could be successfully applied for extraction and determination of naphthalene-derived plant hormones in complex matrices.

Highly dispersed magnetic molecularly imprinted nanoparticles with well-defined thin film for the selective extraction of glycoprotein

Antibody-free analysis is a potential method for glycoprotein analysis, but the development of this method has been limited by its unfavorable selectivity in recent years. Magnetic molecular imprinting, which integrates the fast separation of magnetic materials with high selectivity towards templates in molecular imprinting, was expected to be an effective sample pretreatment in antibody-free analysis for glycoproteins. However, the aggregation of magnetic imprinted nanoparticles and thick molecularly imprinted polymer (MIP) shells on the surface of magnetic carriers caused an unfavorable adsorption capacity, and unsatisfactory rebinding and elution rates, and has limited its application in glycoprotein extraction. Thus, highly dispersed magnetic molecularly imprinted nanoparticles (MMINs) with a well-defined thin film for the selective extraction of glycoprotein HRP were developed in this work. A solvothermal method was used in this work to improve the dispersity of Fe3O4 NPs (nanoparticles) and the MMINs. The thickness of the MIP film was optimized to provide the optimum extraction efficiency. Thus the adsorption capacity of the MMINs, the rebinding rate and the elution rate of the templates were greatly improved. As a result, the prepared MMINs not only exhibited excellent selectivity and high adsorption capacity to HRP, and an outstanding tolerance for interference, but also showed excellent rebinding and elution rates for extraction application. Furthermore, this method provided a reliable way to improve conventional magnetic molecular imprinting, and showed great potential for the analysis of glycoprotein tumor biomarkers in clinics in the future.

Cyclodextrin-Based Microcapsules as Bioreactors for ATP Biosynthesis

A biomimetic energy converter was fabricated via the assembly of CF0F1-ATPase on lipid-coated hollow nanocapsules composed of α-cyclodextrins/chitosan-graft-poly(ethylene glycol) methacrylate. Upon entrapped GOD into these capsules, the addition of glucose could trigger proton-motive force and then drive the rotation of ATPase to synthesize ATP.

Encapsulation studies and selective membrane permeability properties of self-assembly hollow nanospheres

This paper presents a kind of self-assembled hollow nanosphere for enzyme encapsulation. The enzyme molecules were encapsulated in hollow spheres directly in aqueous solution through the self-assembly of rod-coil Alg-g-PEG and α-CDs complexes. These Alg-g-PEG/α-CD hollow spheres showed semi-permeability which could prevent big enzyme molecules from leaving while allowing small substrates and products to pass through to maintain the enzyme activity. The permeability properties of Alg-g-PEG/α-CD hollow nanospheres were investigated by encapsulating different probes. The results showed that the molar mass cutoff (MMCO) of these hollow nanospheres was between 20 and 40 kDa. The encapsulation capability of Alg-g-PEG/α-CD hollow nanospheres was also investigated, the results indicated a maximal values for L-asparaginase encapsulation. Furthermore, the encapsulation behavior for L-asparaginase showed PEG graft density (GD) dependence.