| At present, nano-delivery system has showed lots of advantages in drug delivery. For example, it can reduce drugs toxicity, prolong the blood circulation time, and transmit the drugs to special organs or tissues. In this paper, we did some research on some kinds of drug delivery nanocarriers.Polymer micelles as drug delivery system:targeted the cancer cells by the morphiline groups which have the pH-responsive charge-transfer abilityNano-carriers with positive charges, negative charges, orhydrophobic groups on their surfaces, can absorbproteins and(or) adhere to cell membranes and lead to their clearance by the reticuloendothelial system. To extend carriersresidence time in the blood circulation, hydrophilic and neutral polymers are introduced to surfaces. But the polymers will reduce the carriers’cell permeability. Generally, cell membraneis negative charged, and can absorb the positive charged carriers, which favorable towards to carriers cellular uptake. However, the positivecharged carrierss can easily be cleared in the blood and show little cell selectivity. So micelles withhydrophilic and pH-sensitive surface are chosen, to avoid the particles clearance in the blood circulation and increase the selectivity of the particles in the tumor sites.In this paper, micelles withhydrophilic and pH-responsive morpholinyl groups on surfaces are researched. The protonation/deprotonation of morpholinyl groups isin favor of micelles transporting and targeting to cancer tissues. Polyethylene glycol is biocompatible and water-soluble, avoiding the carrier’s clearance by the RES system. Polylactic acid is biocompatible and biodegradable, achieving the loading and releasingof the hydrophobic drugs.Micelles arebiocompatibleand pH-sensitive.At pH7.4, micelles’ surface is hydrophilic and biocompatible,in favor of micelles in vivo transporting. In slightly acidic (pH6.8-7.2) tumor tissue, the carrier surface is positive charged by the protonation of the morpholinyl groups, and adhere to the cell membrane, accelerating the process of cell uptake by endocytosis. Polymer micelles as drug delivery system which is high drug loading, pH-sensitive and GSH-responsiveDisulfide bonds cross-linked micelles showmany advantages, likestable in physiological pH environment and reductive-response, etc. Glutathione (GSH) is an important reductantin human body. And it is well known that the intracellular concentration of GSH (0.5-10mM) is significantly higher than GSH in blood (20-40uM), and GSH in cancer cells (5-20mM) is higher than in the normal cells.According tothe strongpointsof disulfide bonds and diversity of GSH concentration in body,pH-sensitive and GSH-responsive micelles are prepared. The crosslinked structure of micelles core increases the stability of the micelles and conducives to the micelles blood circulation. The drugs are loaded by the synergetic effect of the hydrophobic and ionic interactions and have high encapsulation amount. And the drug release behavior is pH-sensitive and GSH-responsiveMultifunctional polymer/Fe3O4nanoparticles as drug delivery system which can enter into the cells by the folate receptor-mediated endocytosis processSuperparamagnetic iron oxide nanoparticles, due to their unique physical properties, have attracted research in different fields, such as targeted drug delivery, immunoassays, in-vitro cell separation, magnetic resonance imaging contrast enhancement, hyperthermia, etc.In this paper, a series of polymer-coated magnetic iron oxide nanoparticles with multilayer core-shell architecture are prepared. The core of the nanocarriers is superparamagnetic FesO4nanoparticle, on which the first block (PGMA) of the triblock copolymers is attached. The second block that contains electric charged groups forms the inner shell, can load anticancer with coordinating interaction. The third block (PEG) forms the biocompatible outermost shell. And the folate groups introduce to carriers sufaces, which can conducive the cellular uptake by folate receptor-mediated endocytosis process. |
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