Bifunctional ultraviolet/ultrasound responsive composite TiO₂/polyelectrolyte microcapsules

Abstract

Designing and fabricating multifunctional microcapsules are of considerable interest to both academic and industrial research aspects. This work reports an innovative approach to fabricate composite capsules with high UV and ultrasound responsive functionalities that can be used as external triggers for controlled release, yet with enhanced mechanical strength that can make them survive in harsh environment. Needle-like TiO 2 nanoparticles (NPs) were produced in situ into layer-by-layer (LbL) polyelectrolyte (PE) shells through the hydrolysis of titanium butoxide (TIBO). These rigid TiO 2 NPs yielded the formed capsules with an excellent mechanical strength, showing a free standing structure. A possible mechanism is proposed for their special morphology formation of the TiO 2 NPs and their reinforce effects. Synergistically, their response to UV and ultrasound was visualized via SEM, with results showing an irreversible shell rapture upon exposure to either the UV or ultrasound irradiation. As expected, the release studies revealed that the dextran release from the TiO2/PE capsules was both UV-dependent and ultrasound-dependent. Besides, biocompatibility of the capsules with the incorporation of amorphous TiO 2 NPs was confirmed by MTT assay experiment. All of these evidences suggested a considerable potential medicine application of the TiO 2 /PE capsules for controlled drug delivery.

Intracellularly Biodegradable Polyelectrolyte/Silica Composite Microcapsules as Carriers for Small Molecules

“…The structural and schematic diagram is shown inFigure 1. In fact, the PE capsules dispersed in the precursor solution acted as foreign substrates, which may well promote the heterogeneous nucleation on their surfaces 19,43. Upon adding TEOS to the system, SiO 2 nucleus would initially form within the flexible PE layers as well as their surfaces through heterogeneous nucleation(Figure 1), especially at the positions with low energy, for example, the concave points and pores inside the…”

Inorganic/Organic Multilayer Capsule Composition for Improved Functionality and External Triggering

“…The formed capsules were demonstrated with UV responsiveness, showing a UV-induced release of the encapsulated FAS. [63] The employed titanium source is titanium butoxide (TIBO), which hydrolyzes extremely fast when encountering H 2 O. Different from the Pickering emulsion method, Sukhorukov's group is progressed in the field of TiO 2 coating of PE microcapsules, demonstrating the encapsulation of TRITC-dextran and controlled releasing them by UV irradiation and ultrasound treatment.…”

Multi-layer microcapsules: fresh insights and new applications

“…It offers an effective strategy, which enhances the therapeutic efficacy of many remedies. For example, we reported the preparation of bifunctional ultraviolet-ultrasound-responsive TiO 2 /PE composite microcapsules that could be applied in cosmetics for delivery of bioactive substances on the skin epidermis or protecting the skin from UV light [9]. Such dual-responsive microcontainers are disintegrated under UV light or ultrasound irradiation (Figure 1(e)).…”

“…Figure 1(e,f). Reproduced from [8,9] with permission of American Chemical Society and Royal Chemical Society.…”