Degradable Thermoresponsive Nanogels for Protein Encapsulation and Controlled Release

Reversible addition–fragmentation chain transfer (RAFT) polymerization technique was used for the fabrication of stable core cross-linked micelles (CCL) with thermoresponsive and degradable cores. Well-defined poly­(2-methacryloyloxyethyl phosphorylcholine), poly­(MPC) <i>macro</i>RAFT agent, was first synthesized with narrow molecular weight distribution via the RAFT process. These CCL micelles (termed as nanogels) with hydrophilic poly­(MPC) shell and thermoresponsive core consisting of poly­(methoxydiethylene glycol methacrylate) (poly­(MeODEGM) and poly­(2-aminoethyl methacrylamide hydrochloride) (poly­(AEMA) were then obtained in a one-pot process by RAFT polymerization in the presence of an acid degradable cross-linker. These acid degradable nanogels were efficiently synthesized with tunable sizes and low polydispersities. The encapsulation efficiencies of the nanogels with different proteins such as insulin, BSA, and β-galactosidase were studied and found to be dependent of the cross-linker concentration, size of protein, and the cationic character of the nanogels imparted by the presence of AEMA in the core. The thermoresponsive nature of the synthesized nanogels plays a vital role in protein encapsulation: the hydrophilic core and shell of the nanogels at low temperature allow easy diffusion of the proteins inside out and, with an increase in temperature, the core becomes hydrophobic and the nanogels are easily separated out with entrapped protein. The release profile of insulin from nanogels at low pH was studied and results were analyzed using bicinchoninic assay (BCA). Controlled release of protein was observed over 48 h

Biodegradable and Nontoxic Nanogels as Nonviral Gene Delivery Systems

The development of polymeric systems with tailored properties as nonviral gene carriers continues to be a challenging and exciting field of research. We report here the synthesis and characterization of biodegradable, temperature- and pH-sensitive carbohydrate-based cationic nanogels as effective gene delivery carriers to Hep G2 cells. The temperature-sensitive property of the nanogels allows their facile complexation of DNA, while the pH-sensitive property allows the degradation of nanogels followed by the release of plasmid in the endosome. The nanogels are synthesized via reversible addition–fragmentation chain transfer polymerization (RAFT) technique and are evaluated for their DNA condensation efficacy. The gene delivery efficacies of these nanogels are subsequently studied and it is found that these cationic glyconanogels can serve as potent gene delivery vectors in hepatocytes. It is found that the gene delivery efficacies of this system are similar to that of branched poly­(ethyleneimine), which is used as a positive control. Moreover, these nanogels show desirable properties for systemic applications including low toxicity and degradation in acidic environment

Bismuth trichloride–mediated cleavage of phenolic methoxymethyl ethers

<p>A simple and efficient method for removal of phenolic methoxymethyl ethers in the presence of 30 mol% of bismuth trichloride in acetonitrile/water is described. Notable features of the cleavage protocol entail use of an ecofriendly bismuth reagent, ease of handling, low cost, operational simplicity, and good functional group compatibility. A number of structurally varied phenolic methoxymethyl ethers were cleaved in good to excellent yields.</p

Cationic Poly(2-aminoethylmethacrylate) and Poly(<i>N</i>‑(2-aminoethylmethacrylamide) Modified Cellulose Nanocrystals: Synthesis, Characterization, and Cytotoxicity

Cellulose nanocrystals (CNCs) continue to gain increasing attention in the materials community as sustainable nanoparticles with unique chemical and mechanical properties. Their nanoscale dimensions, biocompatibility, biodegradability, large surface area, and low toxicity make them promising materials for biomedical applications. Here, we disclose a facile synthesis of poly­(2-aminoethylmethacrylate) (poly­(AEM)) and poly­(<i>N</i>-(2-aminoethylmethacrylamide) (poly­(AEMA)) CNC brushes via the surface-initiated single-electron-transfer living radical polymerization technique. The resulting modified CNCs were characterized for their chemical and morphological features using a combination of analytical, spectroscopic, and microscopic techniques. Zeta potential measurements indicated a positive surface charge, and further proof of the cationic nature was confirmed by gold deposition as evidenced by electron microscopy. The cytotoxicity of these cationic modified CNCs was evaluated utilizing a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in two different cell lines, J774A1 (mouse monocyte cells) and MCF-7 (human breast adenocarcinoma cells). The results indicated that none of the cationic modified CNCs decreased cell viability at low concentrations, which could be suitable for biomedical applications