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In order to enhance the targeted delivery of anticancer drugs by polymeric micelles, folic acid (FA), the ligand of folate receptor (FR) over-expressed in the most cancer cells, modified pH-sensitive polymeric micelles were designed and fabricated to encapsulate doxorubicin (DOX) by combination of pH-sensitive amphiphilic polymer poly(2-ethyl-2-oxazoline)-poly(D,L-lactide) with FA-conjugated poly(2-ethyl-2-oxazoline)-poly(D,L-lactide). The prepared micelles were characterized to have about 36 nm in diameter with narrow distribution, well-defined spherical shape observed under TEM and pH-responsive drug release behavior. Moreover, the tumor targeting ability of the FA-modified pH-sensitive polymeric micelles was demonstrated by the cellular uptake, in vitro cytotoxicity to FR-positive KB cells and in vivo real time near-infrared fluorescence imaging in KB tumor-bearing nude mice. The efficient drug delivery by the micelles was ascribed to the synergistic effects of FR-mediated targeting and pH-triggered drug release. In conclusion, the designed FR-targeted pH-sensitive polymeric micelles might be of great potential in tumor targeted delivery of water-insoluble anticancer drugs. [ABSTRACT FROM AUTHOR]

To overcome the main barrier of intestinal epithelium for the oral absorption of poorly water-soluble drugs and further improve their oral absorption, Gly-Sar, the substrate of the oligopeptide transporter PepT1 widely distributed in the small intestine, conjugated poly(ethylene glycol)-block-poly(D,L-lactide) (Gly-Sar-PEG-b-PLA) was designed and synthesized, and PepT1-targeted polymeric micelles were prepared and characterized. The structure of the synthesized Gly-Sar-PEG-b-PLA was confirmed by use of TLC and 1H-NMR. The average molecular weight measured by GPC was 5954 g/mol with PDI of 1.34. The DiI-loaded polymeric micelles from Gly-Sar-PEG-b-PLA with drug loading content of 0.076% were characterized to exhibit 40.36 nm in diameter with PDI of 0.294, and well-defined spherical shape observed by TEM. Furthermore, the PepT1-targeted polymeric micelles profoundly enhanced intestinal absorption of poorly water-soluble drug. Therefore, the designed PepT1-targeted polymeric micelles might have a promising potential for oral delivery of water-insoluble drugs. [ABSTRACT FROM AUTHOR]

Oral administration is the best way for the most patients due to the good compliance, and intestinal epithelium is the main barrier of oral drug absorption. In order to overcome the small intestine epithelial barrier to orally deliver water-insoluble drugs, deoxycholic acid (DA), a substrate of the intestinal bile acid transporters, conjugated poly(2-ethyl-2-oxazoline)-poly(D,L-lactide) (DA-PEOz-PLA) was designed and synthesized, and deoxycholic acid-modified polymeric micelles composed of DA-PEOz-PLA and mPEG-PLA were fabricated to encapsulate model drug coumarin 6 (C6) based on intestinal bile acid pathway. The structure of DA-PEOz-PLA was confirmed using ¹H NMR and TLC, and the molecular weight measured by GPC was 10 034 g/mol with a PDI of 1.51. The C6-loaded polymeric micelles with drug loading content of 0.085% were characterized to have 40.11 nm in diameter and uniform spherical morphology observed by TEM. Furthermore, the deoxycholic acid-modified polymeric micelles were demonstrated to further enhance the transmembrane transport efficiency. The mechanic study evidenced that anchorage of deoxycholic acid onto the micelles surface enriched their transcellular transport pathway. Therefore, the designed deoxycholic acid-modified polymeric micelles might have a promising potential for oral delivery of water-insoluble drugs. [ABSTRACT FROM AUTHOR]

In the present study, we designed and fabricated pH-sensitive polymeric micelles based on the conjugate of poly(2-ethyl- 2-oxazoline)-poly(D,L-lactide) (PEOz-PLA) with doxorubicin (PEOz-PLA-imi-DOX) to efficiently inhibit tumor cell growth. Hence, PEOz-PLA-imi-DOX was successfully synthesized by connecting DOX to the hydrophobic end of pH-sensitive PEOz-PLA via acid cleavable benzoic imine linker and characterized by 1H NMR spectrum and thin layer chromatography. The critical micelle concentration of PEOz-PLA-imi-DOX was determined to be (14.84±3.85) mg/L. The conjugate micelles (denoted as PP-DOX-PM) formed by PEOz-PLA-imi-DOX using film-hydration method were characterized to have a nano-scaled size of about 21 nm in diameter, and the drug loading content was 1.67%. PP-DOX-PM showed pH-dependent drug release behavior with gradually accelerated release of DOX with decrease of pH value, illustrating the micelles' distinguishing feature of endo/lysosomal pH from physiological pH by accelerating drug release. As anticipated, PP-DOX-PM maintained the cytotoxicity of DOX against MDA-MB-231 cells. Collectively, PP-DOX-PM might have great potential for effective suppression of tumor growth. [ABSTRACT FROM AUTHOR]

The intestinal epithelium is the main barrier to the oral delivery of poorly water-soluble drugs. Based on the specific transporters expressed on the apical membrane of the intestinal epithelium, novel polymer micelles targeting to the organic cation transporter 2 (OCTN2) were constructed by combining carnitine conjugated poly(2 -ethyl-2-oxazoline)-poly(D,L-lactide) (Car-PEOz-PLA) with monomethoxy poly(ethylene glycol)-poly(D,L-lactide) (mPEG-PLA). The structure of the synthesized Car-PEOz-PLA was confirmed by ¹H NMR, TLC and ammonium reineckate precipitation reaction, and the number-average molecular weight determined by GPC was 7260 g/mol with a low PDI of 1.44. Coumarin 6-loaded carnitine modified polymeric micelles prepared by film hydration method were characterized to have a nano-scaled size of about 31 nm in diameter, uniform spherical morphology, high drug loading content of 0.098%±0.03% and encapsulation efficiency of 92.67%±2.80%. Moreover, the carnitine-modified micelles exhibited the similar in vitro release behavior in SGF and SIF, and evidently enhanced intestinal absorption of poorly water-soluble agent. Therefore, the designed OCTN2-targeted micelles might have a promising potential for oral delivery of poorly water-soluble drugs. [ABSTRACT FROM AUTHOR]

To improve the oral absorption of poorly water-soluble drugs by overcoming the intestinal epithelium barrier, calcium carbonate nanoparticles targeting to intestine peptide transporter 1 (PepT1) were fabricated by modification of the surface of calcium carbonate nanoparticles with Gly-Sar. Gly-Sar-conjugated TPGS was successfully synthesized and characterized, and coumarin 6-loaded Gly-Sar modified calcium carbonate nanoparticles were then prepared and characterized to have a nano-scaled size of about 193 nm in diameter, cracked surface morphology under a scanning electron microscope, and high drug loading efficiency (60.5±5.9)%. Moreover, the Gly-Sar-modified calcium carbonate nanoparticles exhibited better drug loading stability during the process of their transcellular transport, and evidently enhanced intestinal absorption of poorly water-soluble agents. Therefore, the designed intestine PepT1-targeted calcium carbonate nanoparticles might have a promising potential for oral delivery of poorly water-soluble drugs. [ABSTRACT FROM AUTHOR]