Nano-Carriers Based on pH-Sensitive Star-Shaped Copolymers for Drug-Controlled Release

Abstract

Polymeric nano-carriers are considered as promising tools in biomedical applications due to multiple attractive characteristics including their low toxicity, high loading capacity, controlled drug release capabilities, and highly tunable chemical properties. Here, a series of pH-sensitive star-shaped copolymers, Ad-P[(EMA-co-MAA)-b-PPEGMA]4, was prepared via electron transfer atom radical polymerization (ARGETE ATRP) and selective hydrolysis. These star-shaped copolymers can be self-assembled into micelles (Dh = 150–160 nm) and their critical micelle concentrations (CMC) were estimated to be 3.9–5.0 mg/L. The pH-sensitiveness of the micelles was evidenced by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The maximal paclitaxel (PTX) loading efficiency (DLC) and entrapment efficiency (EE) were 18.9% and 36%, respectively. In vitro release studies revealed that about 19% of the PTX released at an acidic condition of pH 1.2 over 70 h, whereas more than 70% was released within the same time interval at pH 6.8. In vitro cytotoxicity suggested that the low cytotoxicity of the blank micelles, while the PTX-loaded micelles providing the cytotoxicity close to that of free PTX. These results indicated that this novel pH-sensitive nano-carriers have great potential applications for oral drug-controlled release.

Dual Thermo- and Photo-Responsive Micelles Based on Azobenzene-Containing Random Copolymer

“…Figure 8 shows the TEM images of the micellar solution S3 and Nile red-loaded S3 (NR-S3). From the picture, the morphologies of S3 and NR-S3 were basically unchanged except for a little increase in size [ 28 ].…”

“…Materials 2021, 14, x FOR PEER REVIEW 9 of 14 the picture, the morphologies of S3and NR-S3werebasically unchanged except for a little increase in size [28]. UV-visible spectra and fluorescence spectra of S3and NR-S3 are shown in Figure 9, respectively.…”

Polymer-Ligated Nanocrystals Enabled by Nonlinear Block Copolymer Nanoreactors: Synthesis, Properties, and Applications

“…To this end, a star-like triblock copolymer composed of hydrophobic poly(ethyl methacrylate-co-poly-(methacrylic acid) (pH-responsive) as the inner block for both hydropobic drug loading and pH-responsive release, poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) as the intermediate block for magnetic NP formation, and PPEGMA as the outer block for solubility and protective ligand may be rationally designed to render multifunctional properties, that is, as a drug carrier, pH-enabled drug release, and CT imaging. 174 Finally, as discussed above, creating NCs with more complex morphology and architecture may facilitate investigation into their intriguing properties. In this regard, Janus NCs with good intimacy between two constituents (e.g., metals, metal oxides (sulfides), metal carbides, metal nitrides (phosphides), etc.)…”

Playing construction with the monomer toy box for the synthesis of multi‐stimuli responsive copolymers by reversible deactivation radical polymerization protocols

“…Since ATRP initiators consist of aliphatic halides, various architectures for stimuli‐responsive materials become accessible through the structure of ATRP initiators. A tetrabrominated adamantane initiator (Figure 1) was used to perform ARGET ATRP of EMA, t BMA, and oligo(ethylene glycol)methacrylate (OEGMA) to obtain star‐shaped, self‐assembling, pH‐sensitive block copolymers 76 . Functionalization of β‐cyclodextrin with three bromo‐ iso butyryl units per sugar (Figure 1) afforded 20 active sites on each macroinitiator for sequential polymerization with a disulfide‐linked methacrylic prodrug and OEGMA, resulting in a self‐assembling starburst reduction‐sensitive prodrug 77 …”