A Facile Strategy for In Situ Core-Template-Functionalizing Siliceous Hollow Nanospheres for Guest Species Entrapment

The shell wall-functionalized siliceous hollow nanospheres (SHNs) with functional molecules represent an important class of nanocarriers for a rich range of potential applications. Herein, a self-templated approach has been developed for the synthesis of in situ functionalized SHNs, in which the biocompatible long-chain polycarboxylates (i.e., polyacrylate, polyaspartate, gelatin) provide the framework for silica precursor deposition by simply controlling chain conformation with divalent metal ions (i.e., Ca2+, Sr2+), without the intervention of any external templates. Metal ions play crucial roles in the formation of organic vesicle templates by modulating the long chains of polymers and preventing them from separation by washing process. We also show that, by in situ functionalizing the shell wall of SHNs, it is capable of entrapping nearly an eightfold quantity of vitamin Bc in comparison to the bare bulk silica nanospheres. These results confirm the feasibility of guest species entrapment in the functionalized shell wall, and SHNs are effective carriers of guest (bio-)molecules potentially for a variety of biomedical applications. By rationally choosing the functional (self-templating) molecules, this concept may represent a general strategy for the production of functionalized silica hollow structures

Dynamic light scattering and cryogenic transmission electron microscopy investigations on metallo-supramolecular aqueous micelles: evidence of secondary aggregation

Metallo-supramolecular diblock copolymers consisting of a polystyrene (PS) block connected to a poly(ethylene oxide) (PEO) block by a bis(terpyridine)ruthenium complex (PS20-[Ru]-PEOy) were used to prepare aqueous micelles. The length of the PS block was kept constant, while two PEOs of different molecular weight were used. The resulting hydrated micelles and aggregates were characterized by a combination of cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering measurements. The results were compared to those obtained for a covalent counterpart (PS22-b-PEO70). Cryogenic transmission electron microscopy allowed visualization of the PS core of the micelles. Moreover, the aggregates result from clustering of individual micelles

Vesicle-polymer hybrid architectures: A full account of the parachute architecture

We have previously reported that polymerization of styrene in dioctadecyldimethylammonium bromide (DODAB) vesicles leads to so-called parachute-like morphologies where a polymer bead is attached to a vesicle. To learn the constructive principles of these novel polymer colloids, we present here a full characterization study. The dual nature of these particles, combining intrinsic vesicle features with polymer colloid properties, requires characterization methods that address both the morphology (cryo-TEM, AFM, DLS) and the typical vesicle characteristics (micro-DSC, fluorescence techniques, surfactant lysis). It is found that the vesicle characteristics after polymerization are virtually unchanged when compared to the bare vesicles. This observation can be fully accounted for by the putative complete phase separation between polymer and surfactant bilayer matrix. Several methods to release the polymer bead from its parental vesicle are presented. In a second part we investigate the relation between polymerization reaction conditions (i.e., temperature, mode of initiation, molecular weight of the polymer) and the resulting vesicle-polymer hybrid morphology. Unexpectedly, slight modifications in the reaction conditions prove to exert great influence on the produced morphology, resulting in novel vesicle-polymer architectures. It turns out that these variations in morphology are governed by intrinsic vesicle properties. As a general phenomenon, we find that polymerization of styrene in DODAB vesiclesindependent of process parametersinevitably leads to microphase separation between the amphiphilic bilayer matrix and polymer