Fabrication of an asymmetric hollow particle with a thermo-sensitive PNIPAM inside corona

Stimuli-sensitive hollow spheres from chitosan-graft-β-cyclodextrin for controlled drug release

In this paper, sensitive polymeric hollow spheres self-assembled from chitosan-grafted-β-cyclodextrin (CS-g-CD) and sodium tripolyphosphate (TPP) were prepared for controlled release of doxorubicin (DOX). The assemblies were formed by electrostatic interactions between positively charged amino group in CS-g-CD and negatively charged phosphate in TPP. The hollow spheres with diameters about 100nm were confirmed by transmission electron microscopy (TEM) and laser particle analyzer. The microspheres with hollow cavity were beneficial to improve the drug loading capacity for DOX with entrapment efficiency above 60%. The cumulative release of DOX from CS-g-CD/TPP hollow microspheres increased with the decrease of pH and the increase of temperature or ionic strength. At 37 °C and pH 5.2, the maximum drug release was above 90% with a continuous release rate. In-vitro cytotoxicity tests indicate that drug loaded hollow spheres exhibited evidently inhibition against cancer cells. These sensitive polymeric hollow spheres are expected to be used in biomedical field as potential carrier.

Photo-controlled host–guest interaction as a new strategy to improve the preparation of “breathing” hollow polymer nanospheres for controlled drug delivery

Photo-controlled host–guest interaction is used to improve the core removal method for preparing “breathing” hollow nanospheres as drug delivery.

A facile strategy to fabricate glucose-responsive vesicles via a template of thermo-sensitive micelles

Polymer vesicles fabricated based on the complexation between PBA- and GA containing block copolymers exhibited glucose-responsiveness at physiological pH.

Thermo- and pH-sensitive ionic-crosslinked hollow spheres from chitosan-based graft copolymer for 5-fluorouracil release

Thermo- and pH-sensitive ionic-crosslinked hollow spheres from self-assembly of chitosan-graft-poly(N-isopropylacrylamide) (CS-g-PNIPAM) for controlled release of 5-fluorouracil were studied. CS-g-PNIPAM aggregated into core-shell micelles with collapsed PNIPAM as the core and CS as the shell at the temperature above LCST. Ionic crosslinking reagent sodium tripolyphosphate (TPP) was used to crosslink the shell to form hollow spheres after cooling to room temperature. The size of hollow spheres was manipulated by changing pH or temperature of the environment. The CS-g-PNIPAM hollow spheres with plenty of inner cavities showed high loading capacity for 5-fluorouracil due to the polymer-drug interactions. Release of 5-fluorouracil from nanoparticles was accelerated at the temperature above LCST ascribed to the destruction of polymer-drug interactions and the decrease of particles size. Changing pH or ionic strength deformed the structure hollow spheres, which led to the increase of drug release. These hollow nanoparticles with environmentally sensitive properties are expected to be utilized in the field of intelligent drug delivery.

Mechanism of co-nanoprecipitation of organic actives and block copolymers in a microfluidic environment

Microreactors have been shown to be a powerful tool for the production of nanoparticles (NPs); however, there is still a lack of understanding of the role that the microfluidic environment plays in directing the nanoprecipitation process. Here we investigate the mechanism of nanoprecipitation of block copolymer stabilized organic NPs using a microfluidic-based reactor in combination with computational fluid dynamics (CFD) modelling of the microfluidic implementation. The latter also accounts for the complex interplay between molecular and hydrodynamic phenomena during the nanoprecipitation process, in order to understand the hydrodynamics and its influence on the NP formation process. It is demonstrated that the competitive reactions result in the formation of two types of NPs, i.e., either with or without loading organic actives. The obtained results are interpreted by taking into consideration a new parameter representing the mismatching between the aggregations of the polymers and actives, which plays a decisive role in determining the size and polydispersity of the prepared hybrid NPs. These results expand the current understanding of the co-nanoprecipitation mechanism of active and block copolymer stabilizer, and on the role exerted by the microfluidic environment, giving information that could be translated to the emerging fields of microfluidic formation of NPs and nanomedicine.