Peixin He

Multistimulative Nanogels with Enhanced Thermosensitivity for Intracellular Therapeutic Delivery

The flexibility and hydrophilicity of nanogels suggest their potential for the creation of nanocarriers with good colloidal stability and stimulative ability. In the present study, biocompatible AGP and AGPA nanogels with triple-stimulative properties (thermosensitivity, pH sensitivity, and redox sensitivity) were prepared by incorporating poly(N-isopropylacrylamide) (PNIPAM) or poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-AA)) into alginate (AG) emulsion nanodrops, followed by fixation with a disulfide-containing molecule (cystamine dihydrochloride (Cys)). Compared to AG/PNIPAM(AGP) nanogels, AG/P(NIPAM-AA) (AGPA) nanogels exhibited more sensitive volumetric expansion by switching the temperature from 40 to 25 °C under physiological medium. This expansion occurs because P(NIPAM-AA) with -COOH groups can be fixed inside the nanogels via chemical bonding with Cys, whereas PNIPAM was encapsulated in the nanogels through simple physical interactions with the AG matrix. AGPA nanogels carrying an anticancer drug tend to easily enter cells upon heating, thereby exerting toxicity through a cold shock and reverse thermally induced release of an anticancer drug. Upon internalization inside cells, the nanogels use the reducible and acidic intracellular environments to effectively release the drug to the nucleus to impart anticancer activity. These results demonstrate that multifunctional nanogels may be used as a general platform for therapeutic delivery.

pH/redox/thermo-stimulative nanogels with enhanced thermosensitivity via incorporation of cationic and anionic components for anticancer drug delivery

ABSTRACT To explore the potential biomedical applications of nanogels, it is a key factor to improve their thermosensitivity. In this paper, triple-responsive nanogels poly(N-isopropylacrylamide–N,N′-dimethylaminoethyl methacrylate–acrylic acid) (PNDA) were synthesized via in situ incorporating both cationic components and anionic components into a normal thermosensitive polymer matrix. The triple-monomer constructed PNDA nanogels displayed an enhanced thermosensitivity as compared with dual-monomer constructed PND nanogels. The PNDA nanogels presented higher encapsulation efficiency (∼89%) and exhibited better pH/redox/thermo-responsivenesses in an anticancer drug delivery. In vitro biological study indicated that the PNDA nanogels have excellent biocompatibility and improved anticancer cytotoxicity to A549 cells after loading drug DOX. GRAPHICAL ABSTRACT

Preparation of PSt/SiO2 nanoparticles with raspberry-like structure via nonionic surfactant miniemulsion polymerization

Preparation of inorganic/organic nanoparticles (NPs) with special morphology, controllable size, and good stability is important for widening their applications. In this study, a series of polystyrene (PSt)/SiO2 NPs with a raspberry-like structure was synthesized via a miniemulsion polymerization approach, using octaphenyl polyoxyethylene (CA-897) as a nonionic surfactant. To increase silica loading capacity, methacryloyloxyethyl trimethyl ammonium chloride (MTC) was introduced as an auxiliary monomer. The results indicate that the combinative employment of CA-897/SiO2 NPs/MTC could contribute to the formation of raspberry-like PSt/SiO2 nanohybrids with controlled size of 130–370 nm as well as adjustable silica inorganic content of 17–31 wt%, respectively. The raspberry structure played a significant role on the stabilization of PSt/SiO2 NPs in both electrolytic and strong basic/acidic environments.