pH-Sensitive microgels functionalized with folic acid

Effects of additive dosage and coagulation bath pH on amphoteric fluorocarbon special surfactant (FS-50) blend PVDF membranes

Amphiphilic copolymers containing hydrophilic and hydrophobic blocks represented by surfactants have proven to be more effective for modifying membranes than hydrophilic copolymers. However, studies on the effects of additive and coagulation bath pH on the morphology and properties of surfactant-modified membranes have rarely been reported. Hence, this study aims to investigate the effects of the additive dosage and the coagulation bath pH on the mechanisms of phase inversion and performance improvement of amphoteric fluorocarbon special surfactant (FS-50) blended PVDF membranes. It was observed that the pure water flux increased from 114.68 LMH/bar of the original membrane M0 to 205.02 LMH/bar of the blend membrane M1, and then to 615.88 LMH/bar of the coagulation-bath-regulated membrane MPH9 with a high BSA rejection rate of 90.86%, showing a two-stage jump. The addition of FS-50 promoted the instantaneous phase inversion of the membrane, allowing the blend membrane to exhibit a higher proportion of pore characteristics and stronger permeability. After that, the mechanisms of the membrane phase inversion process affected by the coagulation bath pH were interpreted according to the pH-response characteristics of FS-50 in terms of charge repulsion effect and compressed double-electron layer effect. Furthermore, the cross-sectional morphology and the surface structure of the membrane prepared in acidic and alkaline coagulation baths were significantly affected by the pH of the coagulation bath, exhibiting different features. For one, the porosity of the membranes gradually decreased as the acidity and alkalinity of the coagulation bath increased, and the membrane MPH9 exhibited both maximum surface and overall porosity. For another, the coagulation bath pH did not negatively affect the contact angle, surface roughness and tensile strength of the membranes. Overall, adjusting the dosage of FS-50 and the pH of the coagulation bath is a promising approach to greatly enhance membrane performance.

Visible light-induced surfactant-free emulsion polymerization using camphorquinone/tertiary amine as the initiating system for the synthesis of amine-functionalized colloidal nanoparticles

A visible light-induced surfactant-free emulsion polymerization (SFEP) was developed as an alternative pathway for the preparation of amine-functionalized nanoparticles by using the photo-initiating system consisting of camphorquinone coupled with tertiary amine (CQ/3°-amine). Water-soluble macromolecules containing 3°-amines were used as the sources of 3°-amine species, which not only function with CQ to generate initiating free radicals, but also provide colloidal stabilization to the resulting colloidal products. The prepared nanoparticles showed uniformed size distribution and good colloidal stability with positively charged surface. For SFEP induced by CQ/polyethyleneimine (PEI) photo-redox couple, the polymerization of methyl methacrylate (MMA) was affected by both light intensity and initiator concentration. In addition, to obtain higher solid content products, the weight ratio of PEI:MMA=1:4 was employed. Finally, an opportunity for immobilizing various amine containing polymers by our photo-induced SFEP was evaluated. The achievement of this SFEP also depended on 3°-amine content of the macromolecules used.

Folate-decorated succinylchitosan nanoparticles conjugated with doxorubicin for targeted drug delivery

Amphiphilic biodegradable succinylchitosan nanoparticles modified with folic acid are described that act as an emulsifier to form nanoparticles. Their molecular structures and physicochemical as well as self-assembly properties are characterized by means of FT-IR, ¹H NMR, FESEM, DLS, and TEM. The nanoparticles are 60-80 nm in size and are not toxic in vitro. They are immobilized with the cytostatic drug doxorubicin. Specific transport of doxorubicin by the nanoparticles into the folate-receptor-overexpressing cancer cells and its biological activity as well as in vitro release are demonstrated. It is shown that under acidic condition more drug is released. The nanoparticles can thus not only specifically deliver doxorubicin to its target, but also release the drug depending on the pH.

Effect of Gold Nanoparticles on the Thermosensitivity, Morphology, and Optical Properties of Poly(acrylamide-acrylic acid) Microgels

Novel positive thermosensitive microgels of poly(acrylamide-acrylic acid) with embedded gold nanoparticles have been synthesized and characterized by means of dynamic light scattering, UV-vis spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. These systems show temperature (upper critical solution temperature-like volume phase transition) and optical responsiveness making them externally triggered systems.