Structure-controlled zwitterionic nanocapsules with thermal-responsiveness

Abstract

A facile approach is established to prepare zwitterionic nanocapsules (ZNCs) with controlled diameters and core/shell structures based on an inverse reversible addition-fragmentation transfer (RAFT) miniemulsion interfacial polymerization method. The diameters and core volume fractions of ZNCs can be tuned finely from 61 to 220 nm and from 0.22 to 0.61, respectively. Furthermore, the thermal-responsive property of the prepared zwitterionic nanocapsules was systematically studied relating to core/shell ratios and cross-linking degrees. These ZNCs could be particularly useful in constructing polymeric materials with well-defined nanoporous structures for nano-void membranes, drug delivery devices and catalytic carriers.

Zwitterionic Nanocapsules with Salt- and Thermo-Responsiveness for Controlled Encapsulation and Release

“…The 1 H NMR spectrum to confirm the chemical structure of amphi-RAFT agent was shown in Figure S1. The synthetic amphi-RAFT agent served as the emulsifier and RAFT chain transfer agent with a large chain transfer constant. , Then, the mixture was treated by ultrasonication to form plenty of micelles with the assistance of amphi-RAFT, which served as the nanoreactors for polymerization. The monomers were polymerized at the oil–water interface under 40 °C for 8 h, where the synthesized polymer chains were bonded with each other to form the external shell structure and the water molecules continually entering the shell to form the water-phase core simultaneously.…”

“…The drug can be loaded into the ZN C s during the inverse RAFT miniemulsion polymerization. Methyl orange ( M w = 327.33 Da), as a visualized small molecule dye, was a common model drug to investigate the drug encapsulation and release performance of the ZN C s. , The encapsulation efficiency of methyl orange was 89.3%. The released amount of the methyl orange was determined by comparing the UV–vis curves of the solution at different releasing times with the standard absorbance–concentration curves of the drug (462 nm for methyl orange) (Figure S5).…”

“…The amphi-RAFT agent possessed a desired hydrophilic−lipophilic balance (HLB) value for inverse miniemulsion polymerization and was synthesized and purified according to the previously published literature. 40 Specifically, N,N-dimethyl-(acrylamidopropyl) ammonium propane sulfonate (DMAAPS, 1.5 g, 5.5 mmol) and styrene (St, 16.3 g, 156.6 mmol) were sequentially dissolved in benzyl alcohol (56 g) and stirred magnetically to form a homogeneous solution at room temperature. Afterward, a DDMAT (0.1 g, 0.275 mmol) solution (predissolved into 0.5 g of 1,4-dioxane) was evenly mixed and subsequently AIBN (0.0135 g, 0.08 mmol) as an initiator was added dropwise.…”

“…The shell thickness of the ZN C s was directly measured from the TEM images using Image-Pro Plus. The core volume fraction was calculated according to eq where V C represents the volume of the core, V N represents the volume of the ZN C s, l D represents the diameter, and l T represents the shell thickness.…”

Zwitterionic nanocapsule-based wound dressing with the function of gradient release of multi-drugs for efficient wound healing

“…To investigate the release behavior of the ZNs, a common dye, methyl orange (M w = 327.33 Da), was loaded in the ZNs directly during the process of inverse RAFT miniemulsion polymerization, as a modal drug and a visual indicator. 62,63 The released amount of methyl orange could be not only observed through the color variation of the surrounding media, but also could be quantified by measuring its characteristic peak via UV-vis spectra. 42 The cumulative release ratio (%) of the drug was defined by dividing the released amount of substance at specific time intervals by the total released amount at equilibrium.…”