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• PEO-PBO is a newly developed material that has rarely been reported. • PEO-PBO has the advantage of avoiding liver clearance and targeting tumors. • We have successfully used PEO-PBO to load LA-SN38 and produced PEO-PBO loaded LA-SN38 nanoparticles (EBNPs). • EBNPs were more effective in inhibiting the growth of tumor than SNPs and CPT-11. Biodegradable polymeric nanoparticles (NPs) have been used frequently as nanocarriers for anticancer drugs. Linoleic acid conjugated SN38 (LA-SN38)-loaded NPs (EBNPs) were developed using biodegradable poly (ethylene oxide)-poly (butylene oxide) (PEO-PBO) diblock copolymer by titration hydration method without using a toxic organic solvent. The EBNPs had high drug loading efficiency and entrapment efficiency for LA-SN38, at 7.53% and 93.55%, respectively. The polydispersity index (PDI) and average diameter were 0.173 ± 0.019 and 226.1 ± 1.2 nm, respectively. The transmission electron microscope (TEM) image presented that the NPs were homogeneous in size and had spherical structures. In vitro study showed the release behavior of EBNPs was slow and sustained. Furthermore, cytotoxicity and apoptosis assay proved that EBNPs were more effective in growth inhibition of human colon cancer cells. Cell uptake experiments further demonstrated that EBNPs could avoid the phagocytosis by macrophages and promote the uptake by cancer cells. In vivo, EBNPs had prolonged blood circulation time and tumor selectivity in biodistribution. The tumor inhibitory rate of EBNPs was higher compared to SNPs group and CPT-11group (P < 0.01), and the drug did not show significant systemic toxicity at the tested dose. These results indicated that EBNPs are a promising candidate for delivery of LA-SN38 to treat colorectal cancer. [ABSTRACT FROM AUTHOR]

• Validity of fluorescence dyes in reflecting the biodistribution of PTX was evaluated. • PTX-Cy5.5 and mPEG-PLA-Cy5.5 were synthesized and formulated into dye-loaded NPs. • Cy5.5 and Cy5.5 conjugates loaded NPs could truly reflect the biodistribution of PTX. • DiR failed to exactly reflect biodistribution of PTX when solely encapsulated in NPs. Fluorescence imaging is widely used to determine biodistribution of drugs in mice. However, the dye distribution may not be able to exactly reflect the true distribution of drug molecules. We synthesized PTX-Cy5.5 and mPEG-PLA-Cy5.5, and then prepared dye-loaded nanoparticles (NPs) (Cy5.5, DiR, PTX-Cy5.5, and mPEG-PLA-Cy5.5), dye and PTX co-loaded NPs, and PTX-loaded NPs, respectively. The particle sizes of resulting NPs were between 42.7 nm and 68.8 nm, and Zeta potential was between -0.86 mV and -8.49 mV. The biodistribution of fluorescent NPs (dye-loaded NPs and dye and PTX co-loaded NPs) on Bel-7402 tumor-bearing mice was studied via in vivo fluorescence imaging assays, results of which suggested that Cy5.5 loaded NPs and Cy5.5 conjugates (PTX-Cy5.5 and mPEG-PLA-Cy5.5) formulated NPs can reflect the tissue distribution of PTX whether it was incorporated or not. However, DiR failed to reflect true tissue distribution of PTX unless it was co-loaded with PTX. Based on these results, a guidance for the selection of dyes in drug distribution investigations and disease-targeted treatment was presented. [ABSTRACT FROM AUTHOR]

An amphiphilic block copolymer poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) was evaluated as a carrier for therapeutic delivery of paclitaxel (PTX). PEO-PBO and PTX form nanoparticles (NPs) by self-assembly upon hydration. The size of these NPs was about 92.71 nm and the zeta potential was −5.06 mV, which met the requirements for passive tumor targeting through the enhanced permeability and retention effect. Compared with a commonly used block copolymer poly(ethylene glycol)-b-poly-D,L-(lactic acid) (PEG-PDLLA), PEO-PBO forms nanoparticles with superior pharmacokinetic, biodistribution, and tumor inhibitory properties. Meanwhile, results of hemolysis study and CMC determination showed that PEO-PBO had better biocompatibility and stability than PEG-PDLLA. These data suggest that PEO-PBO has potential for application in drug delivery and warrant further evaluation. [ABSTRACT FROM AUTHOR]

7-Ethyl-10-hydroxy-comptothecin (SN38) is an active metabolite of irinotecan (CPT-11) and the clinical application of SN38 is limited by its hydrophobicity and instability. To address these issues, a series of novel amphiphilic mPEG-PLA-SN38-conjugates were synthesized by linking SN38 to mPEG-PLA-SA, and they could form micelles by self-assembly. The effects of mPEG-PLA composition were studied in vitro and in vivo. The mean diameters of mPEG 2K -PLA-SN38 micelles and mPEG 4K -PLA-SN38 micelles were 10–20 nm and 120 nm, respectively, and mPEG 2K -PLA-SN38 micelles showed greater antitumor efficacy than mPEG 4K -PLA-SN38 micelles both in vitro and in vivo. These data suggest that the lengths of mPEG and PLA chains had a major impact on the physicochemical characteristics and antitumor activity of SN38-conjugate micelles. [ABSTRACT FROM AUTHOR]

Paclitaxel and rapamycin have been reported to act synergistically to treat breast cancer. Albeit paclitaxel is available for breast cancer treatment, the most commonly used formulation in the clinic presents side effects, limiting its use. Furthermore, both drugs present pharmacokinetics drawbacks limiting their in vivo efficacy and clinic combination. As an alternative, drug delivery systems, particularly liposomes, emerge as an option for drug combination, able to simultaneously deliver co-loaded drugs with improved therapeutic index. Therefore, the purpose of this study is to develop and characterize a co-loaded paclitaxel and rapamycin liposome and evaluate it for breast cancer efficacy both in vitro and in vivo . Results showed that a SPC/Chol/DSPE-PEG (2000) liposome was able to co-encapsulate paclitaxel and rapamycin with suitable encapsulation efficiency values, nanometric particle size, low polydispersity and neutral zeta potential. Taken together, FTIR and thermal analysis evidenced drug conversion to the more bioavailable molecular and amorphous forms, respectively, for paclitaxel and rapamycin. The pegylated liposome exhibited excellent colloidal stability and was able to retain drugs encapsulated, which were released in a slow and sustained fashion. Liposomes were more cytotoxic to 4T1 breast cancer cell line than the free drugs and drugs acted synergistically, particularly when co-loaded. Finally, in vivo therapeutic evaluation carried out in 4T1-tumor-bearing mice confirmed the in vitro results. The co-loaded paclitaxel/rapamycin pegylated liposome better controlled tumor growth compared to the solution. Therefore, we expect that the formulation developed herein might be a contribution for future studies focusing on the clinical combination of paclitaxel and rapamycin. [ABSTRACT FROM AUTHOR]

Polyethylenimine (PEI) was conjugated to oleic acid (PEI-OA) and evaluated as a delivery agent for LOR-2501, an antisense oligonucleotide against ribonucleotide reductase R1 subunit. PEI-OA/LOR-2501 complexes were further coated with folic acid (FA/PEI-OA/LOR-2501) and evaluated in tumor cells. The level of cellular uptake of FA/PEI-OA/LOR-2501 was more than double that of PEI/LOR-2501 complexes, and was not affected by the expression level of folate receptor (FR) on the cell surface. Efficient delivery was seen in several cell lines. Furthermore, pathway specific cellular internalization inhibitors and markers were used to reveal the principal mechanism of cellular uptake. FA/PEI-OA/LOR-2501 significantly induced the downregulation of R1 mRNA and R1 protein. This novel formulation of FA/PEI-OA provides a reliable and highly efficient method for delivery of oligonucleotide and warrants further investigation. [ABSTRACT FROM AUTHOR]

Although hydrophilic small molecule drugs are widely used in the clinic, their rapid clearance, suboptimal biodistribution, low intracellular absorption and toxicity can limit their therapeutic efficacy. These drawbacks can potentially be overcome by loading the drug into delivery systems, particularly liposomes; however, low encapsulation efficiency usually results. Many strategies are available to improve both the drug encapsulation efficiency and delivery to the target site to reduce side effects. For encapsulation, passive and active strategies are available. Passive strategies encompass the proper selection of the composition of the formulation, zeta potential, particle size and preparation method. Moreover, many weak acids and bases, such as doxorubicin, can be actively loaded with high efficiency. It is highly desirable that once the drug is encapsulated, it should be released preferentially at the target site, resulting in an optimal therapeutic effect devoid of side effects. For this purpose, targeted and triggered delivery approaches are available. The rapidly increasing knowledge of the many overexpressed biochemical makers in pathological sites, reviewed herein, has enabled the development of liposomes decorated with ligands for cell-surface receptors and active delivery. Furthermore, many liposomal formulations have been designed to actively release their content in response to specific stimuli, such as a pH decrease, heat, external alternating magnetic field, ultrasound or light. More than half a century after the discovery of liposomes, some hydrophilic small molecule drugs loaded in liposomes with high encapsulation efficiency are available on the market. However, targeted liposomes or formulations able to deliver the drug after a stimulus are not yet a reality in the clinic and are still awaited. [ABSTRACT FROM AUTHOR]

Nanoparticles are efficient delivery vehicles for cancer therapy such as paclitaxel (PTX). In this study, we formulated PTX into PLGA polymeric nanoparticles. Vitamin E TPGS was used as an emulsifier to stabilize the nanoparticle formulation. PTX was encapsulated in TPGS-emulsified polymeric nanoparticles (TENPs) by a nanoprecipitation method in ethanol–water system. The resultant PTX-TENPs showed a very uniform particle size (∼100 nm) and high drug encapsulation (>80%). The cytotoxicity of PTX-TENPs was examined in A549 lung cancer cell line. Preferential tumor accumulation of TENPs was observed in the A549 lung cancer xenograft model. Tumor growth was significantly inhibited by intravenous injection of PTX-TENPs. Our results suggested that the modified nanoprecipitation method holds great potential for the fabrication of the PTX loaded polymeric nanoparticles. TPGS can be used in the manufacture of polymeric nanoparticles for the controlled release of PTX and other anti-cancer drugs. [ABSTRACT FROM AUTHOR]