Cai-Qi Wang

Oxidation and pH responsive nanoparticles based on ferrocene-modified chitosan oligosaccharide for 5-fluorouracil delivery

Stimuli-responsive nanoparticles based on biodegradable and biocompatible saccharides are potentially superior carriers under different physical conditions. In this study, we present a detailed investigation on the oxidation and pH responses of ferrocene-modified chitosan oligosaccharide (FcCOS) nanoparticles for 5-Fluorouracil (5-FU) Delivery. The dispersion of FcCOS nanoparticles depends strongly on pH change. NaClO, H2O2 and oxygen, as oxidant models, in a weak acid solution displayed varying accelerations as the disassembly progressed. 5-FU, as a drug model, is efficiently uploaded in FcCOS nanoparticle (approximately 238 nm). The in vitro release of 5-FU from FcCOS nanoparticles studies show that the accumulative release increased with the decrease of pH under bubbled N2. Interestingly, the sample under bubbled air has a higher accumulative release up to 59.64% at pH 3.8, compared with samples under bubbled N2 just 49.02%. The results suggested that FcCOS nanoparticles disassembled faster and the release of drug molecules was accelerated because of the synergistic effect of oxidative agent and low pH. Thus, FcCOS can be developed as an effective pH and oxidation dual-responsive carrier to enhance drug efficacy for cancer treatment.

A self-healing and multi-responsive hydrogel based on biodegradable ferrocene-modified chitosan

Here, we present a novel and facile method for constructing a self-healing hydrogel capable of responding to multiple external stimuli via the self-assembly of biodegradable ferrocene-modified chitosan (FcCS) in an acid aqueous solution at a low concentration of 10 mg mL−1. The hydrogel can re-adhere between cut surfaces and self-heal to its original shape and property after being cut, demonstrating an excellent self-healing property, which is also quantitatively proved by rheological measurements. The hydrogel also presents stimuli-responses towards pH, redox, and different ions such as Cd2+, Cr3+, Pb2+, and Cu2+. In addition, the encapsulation and controlled release of doxorubicin hydrochloride (DOX·HCl) in buffer solutions with different pH values were successfully carried out, which suggests that the accumulative release of DOX·HCl increases as the pH value decreases. All these results indicate that this hydrogel is a promising functional and biomedical material.

Hierarchical self-assembly of protoporphyrin IX-bridged Janus particles into photoresponsive vesicles

Control over the building blocks in supramolecule by hierarchical self-assembly techniques provides a flexible strategy in nanotechnology and material science. In this study, a protoporphyrin IX (PPIX)-bridged Janus particle, as an amphiphilic building block, is driven by host–guest recognition between di-β-cyclodextrin-modified PPIX (PPIX-2CD) and azobenzene (AZO)-focused hydrophobic/hydrophilic hyperbranched polymers. The supramolecular Janus particles were hierarchically constructed into photoresponsive vesicles, which disassembled under the irradiation of ultraviolet (UV) light because of the trans- to cis-isomerization of the AZO groups. Results show that the PPIX-inserted vesicles exhibited excellent photostability against intense infrared radiation and good singlet oxygen producing ability.

Multi-morphological self-assembled structures of a rod-coil organometallic oligomer

A rod-coil amphiphilic organometallic oligomer based on o-ferrocenylcarbonyl benzoic acid (FcBA) as hydrophobic short rod and poly(ethylene glycol)17 (PEG17) as hydrophilic coil chain was synthesized via Friedel–Crafts acylation and esterification reaction and characterized by 1H-NMR and FT-IR analyses. The rod-coil oligomer FcBA-PEG17 with short-rod insoluble FcBA segment and long-coil PEG17 segment could self-assemble into multi-morphological aggregates in water such as sphere, rod, strip and vesicle at different initial concentrations, which were characterized by transmission electron microscopy. Interestingly, two different kinds of vesicles were observed, where disfigured vesicles formed at low initial concentration and ideal vesicles at high initial concentration. And the disfigured vesicles can be transferred into ideal vesicles at lower initial concentration through the threading of rigid α-CDs onto the coil PEG17 chains. A possible mechanism for the formation of multi-morphological self-assembled micelles was also proposed.