Copolymer nanoparticles composed of sulfobetaine and poly(ε-caprolactone) as novel anticancer drug carriers

Amphiphilic poly(caprolactone-b-N-hydroxyethyl acrylamide) micelles for controlled drug delivery

To increase the bioavailability and water solubility of hydrophobic medicine, an amphiphilic block copolymer, polycaprolactone-block-polyhydroxyethyl acrylamide (PCL-b-PHEAA), was synthesized.

Protein adsorption and macrophage uptake of zwitterionic sulfobetaine containing micelles

Micelles of poly(ε-caprolactone)-b-poly(N,N-diethylaminoethyl methacrylate)/(N-(3-sulfopropyl-N-methacryloxyethy-N,N-diethylammonium betaine)) (PCL-PDEAPS) and poly(ε-caprolactone)-b-poly(ethylene glycol) (PCL-PEG) were prepared and characterized. The interactions of micelles with model proteins such as bovine serum albumin (BSA), lysozyme (Ly), fibrinogen (Fg) and plasma were studied from adsorption quantity, micelle size, polydispersity index (PDI) and zeta-potential measurements. The adsorption quantity of negatively charged proteins on PCL-PDEAPS micelles containing zwitterionic sulfobetaine is larger than on non-ionic PEG-PCL micelles. The adsorption amount increases with the increase of zwitterionic content. And the quantity of adsorbed Fg is much higher than that of BSA because the former is much larger than the latter. In contrast, adsorption of positively charged Ly on copolymer micelle is very low. The interactions between micelles and model proteins are not only dependent on the hydration of zwitterions in PCL-PDEAPS micelles, but also on the electrostatic effect between proteins and micelles. Moreover, the adsorption of three model proteins on the mixed micelles of PCL-PDEAPS and PCL-PEG copolymers is related to the ratio of two copolymers. Denaturation of the proteins is not detected during adsorption and detachment process. PCL-PDEAPS micelles with positive charge are not swallowed by the macrophages after plasma absorption, in contrast to PCL-PEG micelles.

Stable micelles formed through a stereocomplex of amphiphilic copolymers zwitterionic-(PLLA)2 and MPEG-(PDLA)2 for controlled drug delivery

Y-Shaped amphiphilic copolymers (zwitterionic-(PLLA_2.5K)₂ and MPEG-(PDLA_2.5K)₂) were synthesized through click reaction. The aggregation behavior of the polymers and their stereocomplexes and the DOX release profile from the aggregates were studied.

Characteristic of core materials in polymeric micelles effect on their micellar properties studied by experimental and dpd simulation methods

Polymeric micelles are one important class of nanoparticles for anticancer drug delivery, but the impact of hydrophobic segments on drug encapsulation and release is unclear, which deters the rationalization of drug encapsulation into polymeric micelles. This paper focused on studying the correlation between the characteristics of hydrophobic segments and encapsulation of structurally different drugs (DOX and β-carotene). Poly(ϵ-caprolactone) (PCL) or poly(l-lactide) (PLLA) were used as hydrophobic segments to synthesize micelle-forming amphiphilic block copolymers with the hydrophilic methoxy-poly(ethylene glycol) (mPEG). Both blank and drug loaded micelles were spherical in shape with sizes lower than 50 nm. PCL-based micelles exhibited higher drug loading capacity than their PLLA-based counterparts. Higher encapsulation efficiency of β-carotene was achieved compared with DOX. In addition, both doxorubicin and β-carotene were released much faster from PCL-based polymeric micelles. Dissipative particle dynamics (DPD) simulation revealed that the two drugs tended to aggregate in the core of the PCL-based micelles but disperse in the core of PLLA based micelles. In vitro cytotoxicity investigation of DOX loaded micelles demonstrated that a faster drug release warranted a more efficient cancer-killing effect. This research could serve as a guideline for the rational design of polymeric micelles for drug delivery.

Poly(ethylene glycol)-block-poly(ε-caprolactone)-and phospholipid-based stealth nanoparticles with enhanced therapeutic efficacy on murine breast cancer by improved intracellular drug delivery

BACKGROUND

Effective anticancer drug delivery to the tumor site without rapid body clearance is a prerequisite for successful chemotherapy. 1,2-distearoyl-sn-glycero-3-phospho-ethanolamine-N-(methoxy[polyethyleneglycol]-2000) (DSPE-PEG2000) has been widely used in the preparation of stealth liposomes. Although PEG chains can efficiently preserve liposomes from rapid clearance by the reticuloendothelial system (RES), its application has been hindered by poor cellular uptake and unsatisfactory therapeutic effect.

METHODS

To address the dilemma, we presented a facile approach to fabricate novel stealth nanoparticles generated by poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL), soybean phosphatidylcholine (SPC), and cholesterol, namely LPPs (L represented lipid and PP represented PEG-b-PCL), for the delivery of anticancer drug paclitaxel (PTX). LPPs were prepared using the thin film hydration method. Two PEG-b-PCL polymers with different molecular weights (MW; PEG2000-b-PCL2000, MW: 4,000 Da and PEG5000-b-PCL5000, MW: 10,000 Da) were used to fabricate stealth nanoparticles. Conventional PEGylated liposome (LDP2000, L represented lipid and DP2000 represented DSPE-PEG2000) composed of SPC, cholesterol, and DSPE-PEG2000 was used as the control. The physical properties, cellular uptake, endocytosis pathway, cytotoxicity, pharmacokinetics, tumor accumulation, and anticancer efficacy of free PTX, PTX-loaded LPPs, and LDP2000 were systemically investigated after injection into 4T1 breast tumor-bearing mice.

RESULTS

LPPs were vesicles around 100 nm in size with negative zeta potential. With enhanced stability, LPPs achieved sustainable release of cancer therapeutics. The cellular uptake level was closely related to the PEG chain length of PEG-b-PCL; a shorter PEG chain resulted in higher cellular uptake. Moreover, the cellular internalization of LPP2000 modified by PEG2000-b-PCL2000 on 4T1 cells was 2.1-fold higher than LDP2000 due to the improved stability of LPP2000. The cytotoxicity of PTX-loaded LPP2000 was also higher than that of LDP2000 and LPP5000 as observed using a WST-8 assay, while blank LPPs showed negligible toxicity. Consistent with the results of the in vitro study, in vivo experiments showed that LPPs allowed significantly improved bioavailability and prolonged T1/2β as compared to free PTX injection. More importantly, LPPs mainly accumulated at the tumor site, probably due to the enhanced permeation and retention effect (EPR effect). As a nanomedicine, LPP2000 (tumor inhibition rate of 75.1%) significantly enhanced the therapeutic effect of PTX in 4T1 breast tumor-bearing mice by inhibiting tumor growth compared to LDP2000 and LPP5000 (tumor inhibition rates of 56.3% and 49.5%, respectively).

CONCLUSION

Modification of liposomes with PEG2000-b-PCL2000 can simultaneously improve drug accumulation at the target tumor site and tumor cells, showing great promise for utilization as a PEG modification tool in the fabrication of stealth nanoparticles for cancer chemotherapy.

The effect of architecture/composition on the pH sensitive micelle properties and in vivo study of curcuminin-loaded micelles containing sulfobetaines

The polymeric architecture greatly influences the properties of polymer drug carriers.