Thermosensitive PNVCL‐b‐PEG block copolymer coupled with folic acid was prepared as an anti‐cancer drug carrier. This polymer self‐assembled into stable micelles in aqueous solutions at above 33 °C. At 37 °C, the release profile of PNVCL‐b‐PEG‐FA micelles showed a slower and more controlled release of the entrapped 5‐FU than that at 25 °C. The blank and 5‐FU‐loaded PNVCL‐b‐PEG‐FA micelles did not induce remarkable cytotoxicity against the EA.hy 926 human endothelial cell line; however, 5‐FU‐loaded PNVCL‐b‐PEG‐FA micelles showed a cytotoxicity effect against 4T1 mouse mammary carcinoma cells due to the availability of loaded anti‐cancer drugs delivered to the inside of the cancer cells by the folate‐receptor‐mediated endocytosis process.
The development of thermo‐responsive and reduction‐sensitive polymeric micelles based on an amphiphilic block copolymer poly[(PEG‐MEMA)‐co‐(Boc‐Cyst‐MMAm)]‐block‐PEG (denoted PEG‐P‐SS‐HP) for the intracellular delivery of anticancer drugs is reported. PTX, as model drug, was loaded into the PEG‐P‐SS‐HP micelles with an encapsulation efficiency >90%, resulting in a high drug loading content (up to 35 wt%). The PTX‐loaded PEG‐P‐SS‐HP micelles show slow drug release in PBS and rapid release after incubation with DTT. The PTX‐loaded micelles display a better cytotoxic effect than the free drug, whereas empty micelles are found to be non‐toxic. The thermo‐responsive and reduction‐sensitive polymeric micelles described may serve as promising carriers for cytostatic drugs.
Multifunctional hybrid micelles are prepared from amphiphilic mal‐PEG‐b‐PLA and mPEG‐b‐P(LA‐co‐DHC/RhB) block copolymers. A specific anti‐transferrin receptor antibody, OX26, is linked onto the surface of the micelles. ELISA indicates that the conjugated antibody preserves its activity. OX26 conjugation can increase the uptake efficiency of micelles by target cell lines (C6). Pharmacokinetics and in vivo biodistribution experiments are carried out to investigate the ability of OX26‐conjugated micelles (immunomicelles) to cross the blood–brain barrier. The data show that the brain uptake of OX26‐conjugated micelles is much more than that of OX26‐free ones. Therefore, OX26‐conjugated micelles will be promising drug carriers to cross the blood‐brain barrier.
A new type of fluorescent polymeric micelles is developed by self‐assembly from a series of amphiphilic block copolymers, poly(ethylene glycol)‐b‐poly[styrene‐co‐(2‐(1,2,3,4,5‐pentaphenyl‐1H‐silol‐1‐yloxy)ethyl methacrylate)] [PEG‐b‐P(S‐co‐PPSEMA)]. Their capability of loading doxorubicin (DOX) is investigated by monitoring the loading content, encapsulation efficiency, and photophysical properties of micelles. Förster resonance energy transfer from PPSEMA to DOX is observed in DOX‐loaded micelles, which can serve as an indication of successful encapsulation of DOX in these micelles. The application of this new type of fluorescent polymeric micelles as a fluorescent probe and an anticancer drug carrier simultaneously is explored by studying the intracellular uptake of DOX‐loaded micelles.
The pH sensitivity of a series of PbAEs synthesized from primary amines and diacrylates is studied. By changing alkyl groups of the amine monomers, the pKb can be tuned across a broad range (from 3.5 to 7.2). Micelles formed from a PEG‐PbAE block copolymer retain the pH sensitivity of PbAE and can stably load hydrophobic molecules under neutral pH, while quickly dissociate and release their cargoes at pH ≈ 6.0. When the chemotherapy drug DOX is loaded, the micelles show efficient cell proliferation inhibition to HeLa cells and fast intracellular release. Thus, the primary‐amine‐based PbAEs are shown to be promising in the construction of intracellular targeting drug delivery systems.
A new approach to engineer a local drug delivery system with delayed release using nanostructured surface with nanotube arrays is presented. TNT arrays electrochemically generated on a titanium surface are used as a model substrate. Polymer micelles as drug carriers encapsulated with drug are loaded at the bottom of the TNT structure and their delayed release is obtained by loading blank micelles (without drug) on the top. The delayed and time‐controlled drug release is successfully demonstrated by controlling the ratio of blank and drug loaded‐micelles. The concept is verified using four different polymer micelles (regular and inverted) loaded with water‐insoluble (indomethacin) and water‐soluble drugs (gentamicin).
