RESUMO
Two end-decorated homopolymers, poly(styrene)-beta-cyclodextrin (PS-beta-CD) and poly(ethylene oxide)-ferrocene (PEO-Fc), can orthogonally self-assemble into a supramolecular diblock copolymer (PS-beta-CD/PEO-Fc) in aqueous solutions based on the terminal host-guest interactions. These assemblies can further form supramolecular vesicles, and their assembly and disassembly behaviors can be reversibly switched by voltage through the reversible association and disassociation of the middle supramolecular connection. The vesicles possess an unprecedented property that their assembly or disassembly speed can be controlled by the applied voltage strength. Luminescence spectroscopy demonstrates that the vesicles act as nanocapsules carrying molecules within their hollow cavities and that the external voltage strength accurately regulates the drug release time.
Assuntos
Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos/métodos , Capacitância Elétrica , Polímeros/química , Compostos Ferrosos , Medições Luminescentes , Metalocenos , Nanocápsulas/química , Polietilenoglicóis , Poliestirenos , beta-CiclodextrinasRESUMO
Well-defined cellulose-based dual graft molecular brushes, composed of ethyl cellulose-graft-poly(N,N-dimethylaminoethyl methacrylate)-graft-poly(epsilon-caprolactone) (EC-g-PDMAEMA-g-PCL), have been prepared by ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Unlike other brush copolymers, the new molecular brushes show some unique physicochemical properties and multifunction due to their unique topological structures. These biocompatible copolymers self-assembled to micelles in aqueous solution. Upon pH change, the single micelles further assembled into micellar aggregates. As a result, the micelles in aqueous media could act as excellent drug nanocarriers for controlled drug release. The crystallinity and crystal morphology of the copolymers can be controlled to a certain extent by varying the length of the side chains, which may exert strong spacial restriction and, hence, affect the crystal structures.
Assuntos
Antineoplásicos Alquilantes/química , Clorambucila/química , Colágeno/química , Portadores de Fármacos , Nanotecnologia , Polímeros/química , Materiais Biocompatíveis/química , Varredura Diferencial de Calorimetria , Lasers , Espectroscopia de Ressonância Magnética , Membranas Artificiais , Micelas , Microscopia de Força Atômica , Transição de Fase , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
In this study, liquid-phase microplasma technology (LPMPT) was employed to facilitate the liquefaction of bamboo shoot shell (BSS) in polyethylene glycol 400 (PEG 400) and ethylene glycol (EG) mixture. Effects of liquefaction conditions such as liquefaction time, catalyst percentage, solvent/BSS mass ratio, PEG/EG volume ratio on liquefaction were investigated experimentally. The results showed that the introduction of LPMPT significantly shortened the liquefaction time to 3min without extra heating. The liquefaction yield reached 96.73% under the optimal conditions. The formation of massive reactive species and instantaneous heat accumulation both contributed to the rapid liquefaction of BSS. Thus, LPMPT could be considered as a simple and efficient method for the assistance of biomass fast liquefaction.
Assuntos
Biomassa , Biotecnologia/métodos , Sasa/química , Temperatura Alta , Polietilenoglicóis , SolventesRESUMO
A class of dialkoxyanthracene-containing diblock copolymers is synthesized which possesses visible light-responsivity. These copolymers can self-assemble into a micellar structure in water. Green visible light (540 nm) is able to scissor these anthracene species and cleave the diblock copolymer into two fragments, inducing disassembly of the self-assembled micelles.