One of the most famous anticancer drugs, paclitaxel (PTX), has often been used in drug controlled-release studies. The polymers derived from bio-compound bile acids and degradable poly(ε-caprolactone) (PCL) form a reservoir and have been used as a drug delivery system with great advantages. Herein, we grafted poly(N,N-diethylaminoethyl methacrylate) and poly(poly(ethylene glycol) methyl ether methacrylate) into the bile acid-derived three-armed macroinitiator CA-(PCL)3, resulting in the amphiphilic block copolymers CA-(PCL-b-PDEAEMA-b-PPEGMA)3. These pH-responsive three-armed block copolymers self-assembled into micelles in aqueous solution and PTX was encapsulated into the micellar core to form PTX-loaded micelles with a drug loading of 29.92 wt %. The micelles were stable in PBS at pH 7.4 and showed a pH-triggered release behavior of PTX under acidic environments, in which 55% of PTX was released at pH 5.0 in 80 h. These cholic acid-based functionalized three-armed block polymers present good biocompatibility, showing great potential for drug controlled-release.
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.
A typical amphiphilic star polymer adamantane-[poly(lactic-co-glycolic acid)-bis(2-carboxyethyl) sulfide-poly(ethylene glycol) monomethyl ether)]4 with a specific hydrophilic/redox-sensitive/hydrophobic structure was designed and synthesized through ring opening and esterification reactions. The self-assembled nanomicelles were used as doxorubicin (DOX) delivery vehicles with suitable critical micelle concentrations (5.0 mg/L). After the drug being loaded, drug-loaded micelles showed good drug-loading efficiency (10.39%), encapsulation efficiency (58.1%), and drug release (up to 60%) under simulated biological environment conditions. In addition, the backbone structure of the biodegradable polymer was easily hydrolyzed by the action of biological enzymes. As expected, cell-based studies showed that the designed polymer micelles possessed good biocompatibility (a survival rate of 85% for NH-3T3 cells). Moreover, the drug (DOX) still maintained good anti-cancer effects after being loaded, which caused 40% of MCF-7 cells to survive. These redox-sensitive micelles showed anti-tumor therapeutic potential.
Three
microporous organic frameworks (hereafter denoted as MPOF-Ads) based on a rigid adamantane core have been successfully synthesized
via Sonogashira–Hagihara polycondensation coupling in high
yields, 83.7–94.6%. The obtained amorphous MPOF-Ads networks have high Brunauer–Emmett–Teller surface
areas (up to 737.3 m2 g–1), narrow pore
size distribution (0.95–1.06 nm), and superior thermal (the
initial decomposition temperature T
5% under
an N2 atmosphere can reach 410 °C) and chemical stability
(no apparent degradation in common organic solvents or strong acid/base
solutions after 7 days). At 273 K and 1.0 bar, these MPOF-Ads networks present good uptake capacities for small gas molecules
(13.9 wt % CO2 and 1.66 wt % CH4) for which
the presence of high surface area, predominant microporosity, and
narrow pore size distribution are beneficial. In addition, the as-prepared MPOF-Ads networks possess moderate isosteric heats for CO2 (Q
st = 19.5–30.3 kJ mol–1) and show desired CO2/N2 and
CO2/CH4 selectivity (36.3–38.4 and 4.1–4.3
based on Henry’s law and 17.88–24.92 and 4.24–5.70
based on ideal adsorbed solution theory, respectively). With the demonstrated
properties, the synthesized MPOF-Ads networks display
potential for small gas storage and separation that can be used in
harsh environments because of their superior physical and chemical
stability.
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