Controlled Encapsulation and Release of Substances Based on Temperature and Photoresponsive Nanocapsules

Abstract

In this study, dual-responsive polymeric nanocapsules, in which the state (swelling or collapse) can be repeatedly controlled by external stimuli (i.e., temperature and light), have been designed and prepared through distillation–precipitation polymerization. Temperature sensitive monomers of N-isopropylacrylamide are cross-linked by photoresponsive bis­(methacryloylamino) onto a silica nanospherical template to form a core–shell (SiO2–PNIPAM/Azo) structure. The silica core is then removed by hydrofluoric acid to produce PNIPAM/Azo nanocapsules (P/ANCs) of diameter ∼238 nm at ∼25 °C. The size of the nanocapsule is temperature responsive and, as such, its diameter could be reduced to ∼182 nm on increasing the temperature to 40 °C. In addition, the permeability of nanocapsules can be adjusted by UV irradiation. The cis–trans transformation of modified azobenzene allowed us to perform both the encapsulation and controlled release of molecules. Rhodamine B (RhB) was successfully encapsulated using the photomechanical method. In controlled release experiments, after the majority of RhB (∼45%) was released from the P/ANCs using temperature (∼40 °C) and UV light, a second stage of release could be triggered by lowering the temperature (∼18.4%) and applying UV–visible lighting cycles (∼29.4%), respectively. We found that the diffusion coefficient, D, was 45% larger under alternate irradiation than UV light alone. Our results demonstrate considerable potential for customizable delivery systems for a variety of drugs.

Controlled Drug Release of Modified Mesoporous Silica with Higher Driving Forces Derived from the Accurate Dispersion of Azobenzene Groups

“…The peak at 2900cm − 1 corresponding to the C-H stretching vibration of -CH 3 in CTAB disappeared in the spectrum of SiO 2 -TSUA showing the successful removal of the surfactant [28,29]. Compared to the spectra of TUSA, the characteristic bands at 1550cm − 1 and 3060cm − 1 corresponding to N = N and C-H of azobenzene groups in the spectrum of SiO 2 -TSUA indicated that the TSUA had grafted onto silica successfully [30]. Meanwhile the broad peak at around 3447cm − 1 in the spectrum of SiO 2 corresponding to stretching vibration of O-H shifted to 3350cm − 1 in the spectra of SiO 2 -TSUA indicating that the amino groups were successfully incorporated in silica.…”

Thermal and Photo Dual-Responsive Core–Shell Polymeric Nanocarriers with Encapsulation of Upconversion Nanoparticles for Controlled Anticancer Drug Release

“…Because the azo groups are inhibited to the radical chain reaction by the azo group, it is difficult to form pure azo chromophore particles through emulsion . Our group have successfully obtained photoresponsive polyazobenzene particles by using the distillation precipitation polymerization . When the solvent is distilled at a constant rate, a high monomer conversion could be maintained and a lower monomer concentration at the start of the reaction can prevent the particles from aggregating .…”

“…4,4′-Diaminoazobenzene (DAAB) was synthesized according to the ref . BMAAB was prepared using a temperature dehydration reaction.…”

Synthesis of Yolk–Shell Polymeric Nanocapsules Encapsulated with Monodispersed Upconversion Nanoparticle for Dual-Responsive Controlled Drug Release

“…Similar phenomena in which the external conditions affected the diffusion coefficient were observed. 23,45 Furthermore, the accuracy can be further improved by conjugating targeted biomolecules (e.g., folic acid, transferrin, and monoclonal antibodies) on the nanocapsule surface through the free carboxyl groups (i.e., carbodiimide chemistry). This work successfully demonstrated a yolk−shell structured drug delivery system with pH-and NIR-responsive features.…”