Synthesis, drug release and targeting behaviors of Novel Folated Pluronic F87/poly(lactic acid) block copolymer

Preparation and In vitro Evaluation of Folated Pluronic F87/TPGS Co-modified Liposomes for Targeted Delivery of Curcumin

BACKGROUND

Using targeted liposomes to encapsulate and deliver drugs has become a hotspot in biomedical research. Folated Pluronic F87/D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) co-modified liposomes (FA-F87/TPGS-Lps) were fabricated for curcumin delivery, and intracellular targeting of liposomal curcumin was investigated.

METHODS

FA-F87 was synthesized and its structural characterization was conducted through dehydration condensation. Then, cur-FA-F87/TPGS-Lps were prepared via thin film dispersion method combined with DHPM technique, and their physicochemical properties and cytotoxicity were determined. Finally, the intracellular distribution of cur-FA-F87/TPGS-Lps was investigated using MCF-7 cells.

RESULTS

Incorporation of TPGS in liposomes reduced their particle size, but increased the negative charge of the liposomes as well as their storage stability, and the encapsulation efficiency of curcumin was improved. While, modification of liposomes with FA increased their particle size, and had no impact on the encapsulation efficiency of curcumin in liposomes. Among all the liposomes (cur-F87-Lps, cur-FA-F87-Lps, cur-FA-F87/TPGS-Lps and cur-F87/TPGS-Lps), cur-FA-F87/TPGS-Lps showed highest cytotoxicity to MCF-7 cells. Moreover, cur-FA-F87/TPGS-Lps was found to deliver curcumin into the cytoplasm of MCF-7 cells.

CONCLUSION

Folate-Pluronic F87/TPGS co-modified liposomes provide a novel strategy for drug loading and targeted delivery.

Advances in the therapeutic delivery and applications of functionalized Pluronics: A critical review

Pluronic (PEO-PPO-PEO) block copolymers can form nano-sized micelles with a structure composed of a hydrophobic PPO core and hydrophilic PEO shell layer. Pluronics are U.S. Food and Drug Administration approved polymers, which are widely used for solubilization of drugs and their delivery, gene/therapeutic delivery, diagnostics, and tissue engineering applications due to their non-ionic properties, non-toxicity, micelle forming ability, excellent biocompatibility and biodegradability. Although Pluronics have been employed as drug carrier systems for several decades, numerous issues such as rapid dissolution, shorter residence time in biological media, fast clearance and weak mechanical strength have hindered their efficacy. Pluronics have been functionalized with pH-sensitive, biological-responsive moieties, antibodies, aptamers, folic acid, drugs, different nanoparticles, and photo/thermo-responsive hydrogels. These functionalization strategies enable Pluronics to act as stimuli responsive and targeted drug delivery vehicles. Moreover, Pluronics have emerged in nano-emulsion formulations and have been utilized to improve the properties of cubosomes, dendrimers and nano-sheets, including their biocompatibility and aqueous solubility. Functionalization of Pluronics results in the significant improvement of target specificity, loading capacity, biocompatibility of nanoparticles and stimuli responsive hydrogels for the promising delivery of a range of drugs. Therefore, this review presents an overview of all advancements (from the last 15 years) in functionalized Pluronics, providing a valuable tool for industry and academia in order to optimize their use in drug or therapeutic delivery, in addition to several other biomedical applications.

Preparation and in vitro/vivo evaluation of folate-conjugated pluronic F87-PLGA/TPGS mixed nanoparticles for targeted drug delivery

AIM

Folate-conjugated Pluronic F87-poly(lactic-co-glycolic acid) block copolymer (FA-F87-PLGA) was synthesized to encapsulate anticancer drug Paclitaxel (PTX) for targeted drug delivery. To further improve the curative effect, D-α-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS or Vitamin E TPGS) was added to form FA-F87-PLGA/TPGS mixed NPs.

METHODS

FA-F87-PLGA was synthesized by the ring-opening polymerization and the structure was characterized. PTX-loaded nanoparticles were prepared with the nanoprecipitation method. The physicochemical characteristics were studied to determine the appropriate dose ratio of the FA-F87-PLGA to TPGS. The cytotoxicity against Ovarian Cancer Cells (OVCAR-3) was determined by MTT assay. The Area-Under-the Curve (AUC) and half-life were measured in the vivo pharmacokinetic studies.

RESULTS

Based on the optimization of particle size and embedding rate of PTX-loaded mixed NPs, the appropriate dosage ratio of FA-F87-PLGA to TPGS was finally determined to be 5:3. According to in vitro release studies, the cumulative release rate of PTX-loaded FA-F87-PLGA/TPGS mixed NPs was 92.04%, which was higher than that of nanoparticles without TPGS. The cytotoxicity studies showed that the IC50 value of PTX-loaded FA-F87-PLGA/TPGS decreased by 75.4 times and 19.7 times after 72 h treatment compared with free PTX injections and PTX-loaded FA-F87-PLGA NPs, respectively. In vivo pharmacokinetic studies indicated that FA-F87-PLGA/TPGS mixed NPs had a longer drug metabolism time and a larger Area-Under-the-Curve (AUC) compared with free PTX injections.

CONCLUSION

FA-F87-PLGA/TPGS mixed NPs are potential candidates for targeted drug delivery systems.

Novel folated pluronic F127 modified liposomes for delivery of curcumin: preparation, release, and cytotoxicity

Aim: A novel folated pluronic F127 (FA-F127) was synthesised, so as to modify liposomes with FA group on the surface, and evaluate the effects of FA-F127 modification on the properties of the modified liposomes.Methods: FA was linked to one end of pluronic F127, via the terminal OH group, to obtain FA-F127 and the structure was characterised. FA-F127 modified curcumin liposomes (cur-FA-F127-Lps) were prepared. The physicochemical characteristics of cur-FA-F127-Lps, including morphology and particle size, were studied. The in vitro cytotoxicity of cur-FA-F127-Lps against KB cancer cells was determined by MTT tests.Results: The effects of FA-F127 modification on the average particle size, PDI, curcumin encapsulation efficiency and microstructure were not significant. Compared with nonfolated F127 liposomes (cur-F127-Lps), cur-FA-F127-Lps exhibited significantly higher cytotoxicity towards KB cells.Conclusions: Folic acid modified liposomes provide a novel strategy to improve the chemotherapeutic efficacy of hydrophobic bioactive compounds.

Effect of the Folate Ligand Density on the Targeting Property of Folated-Conjugated Polymeric Nanoparticles

Targeted drug delivery systems have attracted increasing attention due to their ability for delivering anticancer drugs selectively to tumor cells. Folic acid (FA)-conjugated targeted block copolymers, FA-Pluronic-polycaprolactone (FA-Pluronic-PCL) are synthesized in this study. The anticancer drug paclitaxel (PTX) is loaded in FA-Pluronic-PCL nanoparticles by nanoprecipitation method. The in vitro release of PTX from FA-Pluronic-PCL nanoparticles shows slow and sustained release behaviors. The effect of FA ligand density of FA-Pluronic-PCL nanoparticles on their targeting properties is examined by both cytotoxicity and fluorescence methods. It is shown that FA-Pluronic-PCL nanoparticles indicated better targeting ability than non-targeted PCL-Pluronic-PCL nanoparticles. Furthermore, FA-F127-PCL nanoparticle with 10% FA molar content has more effective antitumor activity and higher cellular uptake than those with 50% and 91% FA molar content. These results prove that FA-F127-PCL nanoparticle with 10% FA molar content can be a better candidate as the drug carrier in targeted drug delivery systems.

Targeted folate-conjugated pluronic P85/poly(lactide-co-glycolide) polymersome for the oral delivery of insulin

Aim: To explore the better efficacy of targeted folic acid (FA)-Pluronic 85-poly(lactide-co-glycolide) (FA–P85–PLGA) polymersome in oral insulin delivery. Materials & methods: The cytotoxicity of the polymers, in vitro qualitative and quantitative cellular uptake and the internalization mechanism of insulin-loaded FA–P85–PLGA and PLGA–P85–PLGA polymersomes were studied with the human colon adenocarcinoma cells (Caco-2 cells). Their pharmacodynamics and pharmacokinetics properties were also studied with diabetic rats. Results & conclusion: Polymersomes have shown good biocompatibility. Polymersomes are mainly localized within the cytoplasm of Caco-2 cells from fluorescence microscopy images. FA–P85–PLGA exhibited higher cellular uptake than PLGA–P85–PLGA polymersomes and free fluorescein isothiocyanate-labeled insulin (FITC–insulin) did. The uptake process of targeted polymersomes included clathrin- and caveolae-mediated endocytosis, macropinocytosis and the folate receptor-mediated endocytosis. Insulin-loaded FA–P85–PLGA showed better hypoglycemic effects than insulin-loaded PLGA–P85–PLGA.

The targeting properties of folate-conjugated Pluronic F127/poly (lactic-co-glycolic) nanoparticles

Novel Folated Pluronic F127/poly (lactic-co-glycolic) (FA-F127-PLGA) and PLGA-F127-PLGA block copolymer were synthesized and nanoparticles self-assembled from these two copolymers were prepared by dialysis method. Paclitaxel (PTX) was successfully encapsulated in these two nanoparticles. According to in vitro release studies of PTX-loaded nanoparticles, after an initial burst release during the first 11h, the entrapped PTX released slowly in the following 82h. The cytotoxicity studies demonstrated that the in vitro antitumor effect of PTX could be improved by encapsulating PTX into PLGA-F127-PLGA nanoparticles. Moreover, folate-targeted FA-F127-PLGA nanoparticles were more effective than PLGA-F127-PLGA when delivering PTX in folate receptor overexpressing OVCAR-3 cells, which mainly due to the FA-receptor-meditated endocytosis. As the treatment time became longer, the targeting effects were more obvious. The targeting effect of FA-F127-PLGA nanoparticles was also investigated in vitro by measuring the cellular uptake of the nanoparticles. The results showed that FA-F127-PLGA nanoparticles were more easily to be uptaken by OVCAR-3 cells in comparison with PLGA-F127-PLGA nanoparticles. In vivo pharmacokinetic studies indicated that FA-F127-PLGA nanoparticles prolong the circulation time of PTX in plasma, and delay the blood clearance of PTX. These results indicated that Folated FA-F127-PLGA could be a potential carrier in long-term PTX delivery.

Enhanced effect of folated pluronic F87-PLA/TPGS mixed micelles on targeted delivery of paclitaxel

Targeted drug delivery systems have great potential to overcome the side effect and improve the bioavailability of conventional anticancer drugs. In order to further improve the antitumor efficacy of paclitaxel (PTX) loaded in folated Pluronic F87/poly(lactic acid) (FA-F87-PLA) micelles, D-α-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS or Vitamin E TPGS) were added into FA-F87-PLA to form FA-F87-PLA/TPGS mixed micelles. The LE of PTX-loaded mixed micelles (13.5%) was highest in the mass ratio 5 to 3 of FA-F87-PLA to TPGS. The in vitro cytotoxicity assays indicated that the IC50 values for free PTX injections, PTX-loaded FA-F87-PLA micelles and PTX-loaded FA-F87-PLA/TPGS mixed micelles after 72h of incubation were 1.52, 0.42 and 0.037mg/L, respectively. The quantitative cellular uptake of coumarin 6-loaded FA-F87-PLA/TPGS and FA-F87-PLA micelles showed that the cellular uptake efficiency of mixed micelles was higher for 2 and 4h incubation, respectively. In vivo pharmacokinetic studies found that the AUC of PTX-loaded FA-F87-PLA/TPGS mixed micelles is almost 1.4 times of that of PTX-loaded FA-F87-PLA micelles. The decreased particle size and inhibition of P-glycoprotein effect induced by the addition of TPGS could result in enhancing the cellular uptake and improving the antitumor efficiency of PTX-loaded FA-F87-PLA/TPGS mixed micelles.

Novel folated Pluronic/poly(lactic acid) nanoparticles for targeted delivery of paclitaxel

In vivo prolonged circulation time and enhanced tumor resistant ability of targeted PTX-loaded FA–Pluronic–PLA nanoparticles.