Synthesis and characterization of poly(N-isopropylacrylamide-co-N,N′-methylenebisacrylamide-co-acrylamide) core – Silica shell nanoparticles by using reactive surfactant polyoxyethylene alkylphenyl ether ammonium sulfate

Folic acid conjugated palygorskite/Au hybrid microgels: Temperature, pH and light triple-responsive and its application in drug delivery

Herein, folic acid conjugated poly (NIPAM-co-functional palygorskite-Au-co-acrylic acid) (FA-PNFA) hybrid microgels were fabricated by emulsion polymerization. The introduction of acrylic acid can increase the low critical solution temperature (LCST) of FA-PNFA from 36 °C at pH 5.5-42 °C at pH 7.4. Doxorubicin hydrochloride (DOX) was chosen as the load drug, the results show that the DOX release behavior is driven by temperature, pH and light. Cumulative drug release rate can reach 74 % at 37 °C and pH 5.5 while only 20 % at 37 °C and pH 7.4, which effectively avoided the early leakage of the drug. In addition, by exposing FA-PNFA hybrid microgels to laser irradiation, the cumulative release rate was increased by 5 % compared to the release rate under dark conditions. Functional palygorskite-Au as physical crosslinkers not only improves the drug loading content of microgels but also promotes the release of DOX through light drive. Methyl thiazolyl tetrazolium bromide (MTT) assay demonstrated that the FA-PNFA are nontoxic up to 200 μg mL-1 towards 4T1 breast cancer cell. Meanwhile, DOX-loaded FA-PNFA show more significant cytotoxicity than the free DOX. Confocal laser scanning microscope (CLSM) revealed that the DOX-loaded FA-PNFA could be efficiently taken by 4T1 breast cancer cells. FA-PNFA hybrid microgels not only improve the LCST of PNIPAM, but also endow the microgels with photostimulation responsiveness, which can release drugs in response to the triple stimulation response of temperature, pH and light, thus effectively reducing the activity of cancer cells, making them more promising for wider medical applications.

Multifunctional Oxidized Succinoglycan/Poly(N-isopropylacrylamide-co-acrylamide) Hydrogels for Drug Delivery

We prepared the self-healing and temperature/pH-responsive hydrogels using oxidized succinoglycan (OSG) and a poly (N-isopropyl acrylamide-co-acrylamide) [P(NIPAM-AM)] copolymer. OSG was synthesized by periodate oxidation of succinoglycan (SG) isolated directly from soil microorganisms, Sinorhizobium meliloti Rm1021. The OSG/P(NIPAM-AM) hydrogels were obtained by introducing OSG into P(NIPAM-AM) networks. The chemical structure and physical properties of these hydrogels were characterized by ATR-FTIR, XRD, TGA, and FE-SEM. The OSG/P(NIPAM-AM) hydrogels showed improved elasticity, increased thermal stability, new self-healing ability, and 4-fold enhanced tensile strength compared with the P(NIPAM-AM) hydrogels. Furthermore, the 5-FU-loaded OSG/P(NIPAM-AM) hydrogels exhibited effective temperature/pH-responsive drug release. Cytotoxicity experiments showed that the OSG/P(NIPAM-AM) hydrogels were non-toxic, suggesting that OSG/P(NIPAM-AM) hydrogels could have the potential for biomedical applications, such as stimuli-responsive drug delivery systems, wound healing, smart scaffolds, and tissue engineering.

Synthesis and Characterization of a Core-Shell Copolymer with Different Glass Transition Temperatures

The aim of this study is to synthesize an organic core-shell co-polymer with a different glass transition temperature (Tg) between the core and the shell that can be used for several applications such as the selective debonding of coatings or the release of encapsulated materials. The co-polymer was synthesized using free radical polymerization and was characterized with respect to its morphology, composition and thermal behavior. The obtained results confirmed the successful synthesis of the co-polymer copolymer poly(methyl methacrylate)@poly(methacrylic acid-co-ethylene glycol dimethacrylate), PMMA@P(MAA-co-EGDMA), which can be used along with water-based solvents. Furthermore, the Tg of the polymer’s core PMMA was 104 °C, while the Tg of the shell P(MAA-co-EGDMA) was 228 °C, making it appropriate for a wide variety of applications. It is worth mentioning that by following this specific experimental procedure, methacrylic acid was copolymerized in water, as the shell of the copolymer, without forming a gel-like structure (hydrogel), as happens when a monomer is polymerized in aqueous media, such as in the case of super-absorbent polymers. Moreover, the addition and subsequent polymerization of the monomer methyl methacrylate (MAA) into the mixture of the already polymerized PMMA resulted in a material that was uniform in size, without any agglomerations or sediments.

Cross-Linked Polymers as Scaffolds for the Low-Temperature Preparation of Nanostructured Metal Oxides

The current state of the art of the use of cross-linked organic polymers, both insoluble (resins or gels) and soluble (micro- and nanogels), as aids for the low-temperature preparation of stable metal oxide nanoparticles or nanostructured metal oxides is reviewed herein. Synthetic strategies for inorganic oxide nanomaterials of this kind can greatly benefit from the use of cross-linked polymers, which may act as scaffolds/exotemplates during inorganic nanoparticle synthesis, or as stabilizers following post-synthetic modification of the nanoparticles. Furthermore, the peculiar properties of the organic cross-linked polymers add to those of the inorganic oxide nanoparticles, producing materials with combined properties. The potential applications of such highly promising composite nanomaterials will be also briefly sketched.