Effect of anionic PEGylated polypeptide on gene transfection mediated by glycolipid conjugate micelles.

To improve the gene transfection efficiency mediated by chitosan-g-stearic acid (CS) micelles, poly(ethylene glycol)-b-poly(γ-glutamic acid) (PG) was incorporated into a CS-based gene delivery system. CS/PG/pDNA complexes were prepared by ionic interaction. CS and PEGylated CS (PCS) micelles were introduced to prepare binary complexes for use as controls. CS/PG/pDNA complexes possessed similar sizes and presented as irregular spheroids in shape. The incorporation of PG into CS/pDNA complexes did not affect the ability of CS to compact pDNA and also showed a protective effect against DNase I based degradation of pDNA. Importantly, PG could increase gene transfection efficiency, which was also affected by the mixing methods used for the preparation of CS/PG/pDNA ternary complexes. The transfection efficiencies mediated by CS/PG/pDNA complexes against HEK293 and EC-1 cells reached up to 40.8% and 11.6%, respectively, which were much higher than those of CS/pDNA complexes (1.3% and 4.0%) and PCS/pDNA complexes (0.8% and 2.4%). In addition, the incorporation of PG into CS/pDNA complexes significantly enhanced cellular uptake in HEK293 and EC-1 cells and, additionally, improved endosomal escape and intracellular vector unpacking. However, the incorporation of PG reduced the cellular uptake of CS/PG/pDNA complexes in macrophages (RAW264.7 cells). It was further demonstrated that, in addition to a nonspecific charge-mediated binding to cell membranes, a γ-PGA-specific receptor-mediated pathway was involved in the internalization of CS/PG/pDNA complexes. These results indicated that PG played multiple important roles in enhancing the transfection efficiency of CS/PG/pDNA complexes.

High tolerated paclitaxel nano-formulation delivered by poly (lactic-co-glycolic acid)-g-dextran micelles to efficient cancer therapy.

The amphiphilic graft copolymer poly (lactic-co-glycolic acid)-g-dextran (Dex-PLGA) was successfully synthesized to fabricate micelles for the delivery of paclitaxel with low critical micelle concentration (CMC). The sizes of paclitaxel-loaded Dex-PLGA (Dex-PLGA/PTX) micelles were kept below 100nm with a relatively narrow size distribution. This novel PTX nano-formulation was found to exhibit slightly stronger in vitro cytotoxicity against SKOV-3, OVCAR-8 and MCF-7 cells with Taxol®. However, it could overcome the drug resistance of multi-drug resistant human breast carcinoma cells (MCF-7/Adr cells). The maximum tolerated dose (MTD) of Dex-PLGA/PTX after a single dose was more than 200mg PTX/kg, which were 8-fold higher than that of Paclitaxel Injection. The in vivo antitumor activity results indicated that Dex-PLGA/PTX micelles treatments effectively suppressed the tumor growth and highly reduced the toxicity against animals than Taxol® and could eliminate the SKOV-3 tumor by highly increasing the drug dose. FROM THE CLINICAL EDITOR: Chemotherapy for cancer has always been hampered the toxic side effect of the drugs. Nanotechnology has helped to produce various drug delivery systems to minimize these side effects. In this article, the authors designed dextran-based micelles loaded with paclitaxel. They showed effective anti-tumor activity in both in vitro and in vivo experiments with significant lower systemic toxicity.

Improved transport and absorption through gastrointestinal tract by PEGylated solid lipid nanoparticles.

The aim of the present study was to evaluate the potential of PEGylated solid lipid nanoparticle (pSLN) as mucus penetrating particles (MPP) for oral delivery across gastrointestinal mucus. The SLN was prepared by an aqueous solvent diffusion method, subsequently modified with PEG2000-stearic acid (PEG2000-SA) as hydrophilic groups. Surface properties, cytotoxicity, cellular uptake, and transport across Caco-2/HT29 coculture cell monolayers, intestinal absorption, and pharmacokinetics of pSLN were studied compared with that of SLN. Quantitative cellular uptake showed that the internalization of SLN and pSLN was an active transfer process, which would be restrained by several inhibitors of cell activity. Compared with SLN, the permeation ability of pSLN decreased through Caco-2 cell monolayer while it increased through a mucus-secreting Caco-2/HT29 coculture cell monolayer, which indicated that the mucus layer has a significant impact on determining the efficiency of oral nanoformulations. In addition to increasing permeation ability, the stability of the nanoparticles in simulated intestinal fluids was also increased by the PEGylation. Moreover, in vitro everted gut sac technique and the ligated intestinal loops model in vivo also demonstrated that pSLN can rapidly penetrate mucus secretions, whereas the SLN were strongly trapped by highly viscoelastic mucus barriers. The pharmacokinetic studies presented that pSLN exhibited improved absorption efficiency and prolonged blood circulation times with a 1.99-fold higher relative bioavailability compared with SLN. In conclusion, PEGylated solid lipid nanoparticles had advantages in enhancing the bioavailability of oral administration.

pH triggered doxorubicin delivery of PEGylated glycolipid conjugate micelles for tumor targeting therapy.

The main objective of this study was aimed at tumor microenvironment-responsive vesicle for targeting delivery of the anticancer drug, doxorubicin (DOX). A glucolipid-like conjugate (CS) was synthesized by the chemical reaction between chitosan and stearic acid, and polyethylene glycol (PEG) was then conjugated with CS via a pH-responsive cis-aconityl linkage to produce acid-sensitive PEGylated CS conjugates (PCCS). The conjugates with a critical micelle concentration (CMC) of 181.8 µg/mL could form micelles in aqueous phase, and presented excellent DOX loading capacity with a drug encapsulation efficiency up to 87.6%. Moreover, the PCCS micelles showed a weakly acid-triggered PEG cleavage manner. In vitro drug release from DOX-loaded PCCS micelles indicated a relatively faster DOX release in weakly acidic environments (pH 5.0 and 6.5). The CS micelles had excellent cellular uptake ability, which could be significantly reduced by the PEGylation. However, the cellular uptake ability of PCCS was enhanced comparing with insensitive PEGylated CS (PCS) micelles in weakly acidic condition imitating tumor tissue. Taking PCS micelles as a comparative group, the PCCS drug delivery system was demonstrated to show much more accumulation in tumor tissue, followed by a relatively better performance in antitumor activity together with a security benefit on xenograft tumor model.

Stearic acid-g-chitosan polymeric micelle for oral drug delivery: in vitro transport and in vivo absorption.

Stearic acid-g-chitosan (low molecular weight chitosan CS-SA) with different amino-substituted degrees was synthesized and evaluated as an oral delivery vehicle in this paper. Synthesized CS-SA with 4.47%, 24.36% and 40.36% amino-substituted degree (SD) could form micelles by self-aggregation in aqueous medium. The critical micelle concentration (CMC) ranged from about 0.16 to 0.25 mg/mL, which decreased with the increased SD of CS-SA. The CS-SA micelles had 33.4-130.9 nm size and 22.9- 48.4 mV zeta potential. CS-SA with higher SD had the smaller size and the higher zeta potential. The permeability and possible transport route of CS-SA micelles across the gastrointestinal tract was investigated by in vitro model Caco-2 cells. The results exhibited that the CS-SA micelles had good permeability, and the permeability enhanced with increasing SD of the CS-SA. The transport of the micelles showed energy, pH and concentration dependent transcytosis process, mainly through macropinocytosis and partly via fluid-phase transcytosis and caveolar route. The reversible decrease in transepithelial electrical resistance (TEER) by treatment of micelles suggested that paracellular transport pathway was another route of the micelles crossing the gastrointestinal tract. Using doxorubicin (DOX) as a model drug, the permeation results further demonstrated that the DOX transport mediated by CS-SA micelles could avoid efflux via P-glycoprotein. In vivo study demonstrated that the micelles could significantly improve the bioavailability of encapsulated drug. The results presented that the CS-SA with higher SD was a promising vehicle for oral drugs.

Thermal-sensitive lipid nanoparticles potentiate anti-PD therapy through enhancing drug penetration and T lymphocytes infiltration in metastatic tumor.

The response rate of anti-PD therapy in most cancer patients remains low. Therapeutic drug and tumor-infiltrating lymphocytes (TILs) are usually obstructed by the stromal region within tumor microenvironment (TME) rather than distributed around tumor cells, thus unable to induce the immune response of cytotoxic T cells. Here, we constructed the cationic thermosensitive lipid nanoparticles IR780/DPPC/BMS by introducing cationic NIR photosensitizer IR-780 iodide (IR780) modified lipid components, thermosensitive lipid DPPC and PD-1/PD-L1 inhibitor BMS202 (BMS). Upon laser irradiation, IR780/DPPC/BMS penetrated into deep tumor, and reduced cancer-associated fibroblasts (CAFs) around tumor cells to remodel the spatial distribution of TILs in TME. Interestingly, the cationic IR780/DPPC/BMS could capture released tumor-associated antigens (TAAs), thereby enhancing the antigen-presenting ability of DCs to activate cytotoxic T lymphocytes. Moreover, IR780/DPPC/BMS initiated gel-liquid crystal phase transition under laser irradiation, accelerating the disintegration of lipid bilayer structure and leading to the responsive release of BMS, which would reverse the tumor immunosuppression state by blocking PD-1/PD-L1 pathway for a long term. This combination treatment can synergistically exert the antitumor immune response and inhibit the tumor growth and metastasis.

Chitosan-modified lipid nanodrug delivery system for the targeted and responsive treatment of ulcerative colitis.

Targeted and sensitive drug release at the colitis site is critical for the effective therapy of ulcerative colitis and reduction of side effects from the drug. Herein, we used 3,3'-dithiodipropionic acid (DTPA) to covalently link quercetin (Qu) and glyceryl caprylate-caprate (Gcc) via ester bonds to prepare Qu-SS-Gcc lipid nanoparticles (Qu-SS-Gcc LNPs). Dexamethasone (Dex) was used as a model drug, and chitosan (CSO) was modified on the surface of Qu-SS-Gcc LNPs to obtain CSO-modified Dex-loaded Qu-SS-Gcc LNPs (CSO/Dex/LNPs). The encapsulation efficiency and drug loading of CSO/Dex/LNPs were 93.1 % and 8.1 %, respectively. The in vitro release results showed that CSO/Dex/LNPs had esterase-responsive characteristics and could release the drug rapidly in esterase-containing artificial intestinal fluid. A human colorectal adenocarcinoma cell (Caco-2) monolayer was used as the intestinal cell barrier model. Transmembrane resistance measurements and permeation experiments showed that CSO/Dex/LNPs had a protective effect on the lipopolysaccharide (LPS)-stimulated Caco-2 cell monolayer and increased the expression of E-cadherin in LPS-stimulated Caco-2 cells. Moreover, CSO/Dex/LNPs could significantly reduce the expression of the inflammatory factors TNF-α, IL-6 and NO in LPS-stimulated RAW 264.7 cells. The ulcerative colitis mouse model was constructed by using C57BL/6 mice. The in vivo distribution results showed that CSO/Dex/LNPs had colon-targeting effects and strong retention ability in the colons of mice with colitis. The results also showed that CSO/Dex/LNPs had better anti-inflammatory effects than free Dex, which could reduce colonic atrophy, reduce histomorphological changes and increase the expression of E-cadherin in the colon. Furthermore, the expression levels of TNF-α, IL-6 and NO in the CSO/Dex/LNP-treated group were 37.4 %, 35.5 % and 33.2 % of those in mice with colitis, respectively.

Redox-responsive chitosan oligosaccharide-SS-Octadecylamine polymeric carrier for efficient anti-Hepatitis B Virus gene therapy.

DrzBC and DrzBS (10-23 DNAzyme) could block the expression of HBV e- and s- gene respectively. But the application of 10-23 DNAzyme was limited owing to the lack of appropriate delivery vehicles. Chitosan oligosaccharide-SS-Octadecylamine (CSSO), a redox-responsive nano-sized polymeric carrier, could self-aggregate and bind with DNA by electrostatic interaction at proper mass ratio. Compared with the traditional commercial carrier Lipo2000, CSSO exhibited lower cytotoxicity, efficient cellular uptake by targeting cells, and rapidly DNA released in cytoplasm after escaping from endosomes. Including the same DNA concentration, Lipo2000/(DrzBC or DrzBS) showed maximum inhibitory rate on HBeAg (47.29 ±â€¯1.86%) and HBsAg (33.58 ±â€¯0.72%) secretion after 48 h incubation, and then both decreased. In contrast, HBeAg secretion inhibition by CSSO/DrzBC and HBsAg secretion inhibition by CSSO/DrzBS were up to 73.86 ±â€¯1.77% and 67.80 ±â€¯2.51% at 48 h, and further increased to 83.83 ±â€¯2.34% and 76.79 ±â€¯2.18% at 72 h, respectively. CSSO is a promising redox-responsive polymeric carrier for efficient anti-Hepatitis B Virus gene therapy.

Cellular uptake and cytotoxicity of shell crosslinked stearic acid-grafted chitosan oligosaccharide micelles encapsulating doxorubicin.

Stearic acid-grafted chitosan oligosaccharide (CSO-SA) with 3.48% amino-substituted degree (SD%) was synthesized by coupling reaction. The CSO-SA could self-aggregate to form micelle with a critical micelle concentration (CMC) at 0.035 mg/mL in the aqueous phase. The CSO-SA self-aggregate micelles indicated spatial structure with multi-hydrophobic core. One CSO-SA chain could form 2.8 hydrophobic cores. Cellular uptakes of CSO-SA micelles by using A549, LLC, and SKOV3 cells as model tumor cell lines showed the faster cellular internalization of CSO-SA micelles, and the cellular uptakes on the LLC and SKOV3 cells were higher than that on the A549 cells. Doxorubicin (DOX) was then used as a model drug to incorporate into CSO-SA micelles. To reduce the initial burst drug release from CSO-SA micelles loading DOX (CSO-SA/DOX), the shell of CSO-SA micelles was crosslinked by glutaraldehyde. The shell crosslinking of CSO-SA micelles reduced the micelle size and surface potential, but it did not significantly affect the cellular uptake and drug encapsulation efficiency of CSO-SA micelles. The cellular inhibition experiments demonstrated that the cytotoxicity of DOX was increased by the encapsulation of CSO-SA micelles. CSO-SA/DOX displayed the best antitumor efficacy in SKOV3 cell line due to the higher cellular uptake percentage of CSO-SA micelles and the lower sensitivity of free drug to the cells. The cytotoxicities of shell crosslinked CSO-SA/DOX were highly enhanced in all cell lines than those of unmodified CSO-SA/DOX.

PEGylated chitosan-based polymer micelle as an intracellular delivery carrier for anti-tumor targeting therapy.

Stearic acid-grafted chitosan oligosaccharide (CSO-SA) micelles presented a potential candidate for intracellular drug delivery carrier due to its special spatial structure. In this article, CSO-SA was further modified by polyethylene glycol (PEG). The physicochemical properties of PEGylated CSO-SA (PEG-CSO-SA) micelles were characterized. After PEGylation, the critical micelle concentration (CMC) of PEG-CSO-SA had no significant change; the micelle size increased; and the zeta potential decreased. The cellular uptake of CSO-SA micelles before and after PEGylation in macrophage RAW264.7, immortalized rat liver cells BRL-3A and human liver tumor cells HepG2 was studied. About 58.4+/-0.63% of CSO-SA micelles were uptaked by RAW264.7 in 24h, however, only 17.7+/-0.94% of PEG-CSO-SA micelles were internalized into RAW264.7 after the CSO-SA was modified with PEG in five molar times. Meanwhile, there were no changes in the uptake after PEGylation of CSO-SA in BRL-3A and HepG2. Using mitomycin C as a model drug, the in vitro anti-tumor activities of the drug loaded in the micelles were investigated. The 50% cellular growth inhibition (IC(50)) of the drug decreased from 1.97+/-0.2 to 0.13+/-0.02mug/mL after mitomycin C was loaded into CSO-SA micelles, and the IC(50) value of the drug had no obvious change when the CSO-SA was modified by PEG.

Cellular uptake of solid lipid nanoparticles and cytotoxicity of encapsulated paclitaxel in A549 cancer cells.

The aim of this study was to investigate the cellular uptake of solid lipid nanoparticles (SLN) and cytotoxicity of its paclitaxel delivery system. The conjugate of octadecylamine-fluorescein isothiocyanate (ODA-FITC) was synthesized, and used as a marker to prepare fluorescent SLN. The cellular uptakes of fluorescent SLN with different lipid material were evaluated by fluorescence microscopy and the measurement of fluorescence intensity. The order of cellular uptake ability was glycerol tristearate SLN>monostearin SLN>stearic acid SLN>Compritol 888 ATO SLN (ATO888 SLN). The cellular cytotoxicities of paclitaxel were highly enhanced by the encapsulation of lipid matrix. Due to the lower drug entrapment efficiency of glycerol tristearate SLN, monostearin SLN was considered as the best lipid material to improve the cytotoxicity of drug. The polyethylene glycol monostearate (PEG-SA) and the synthesized conjugate of folic acid-stearic acid (FA-SA) were further introduced into monostearin SLN, respectively. The PEG and folate modified SLN could enhance the cellular uptake of SLN and the cellular cytotoxicity of drug by the membrane disturb ability of PEG chains on the SLN surface and the improved endocytosis mediated by folate receptor.

Studies on PEG-modified SLNs loading vinorelbine bitartrate (I): preparation and evaluation in vitro.

In this study, the conjugate of PEG2000-stearic acid (PEG2000-SA) was used to prepare PEGylated solid lipid nanoparticles loading vinorelbine bitartrate (VB-pSLNs) by cold homogenization technique. The particle size and zeta potential of resulted VB-pSLNs ranged 180-250nm and 0-10mV, which were determined using a Zetasizer, respectively. Although the drug entrapment efficiency (EE) slightly decreased after the PEG modification of VB-SLNs, above 60 % EE could be reached. The drug release tests in vitro indicated the faster drug release from VB-pSLNs than that from VB-SLNs without PEG modification. To investigate the cellular uptake of VB-pSLNs, the chemical conjugate of octadecylamine-fluorescein isothiocynate (FITC-ODA) was synthesized, and was used as a fluorescence marker to incorporate into nanoparticles. The results from cellular uptake indicated that the phagocytosis of VB-pSLNs by RAW264.7 cells was inhibited effectively by the PEG modification of SLNs, while the uptake by cancer cells (MCF-7 and A549) could be improved significantly. The assay of anticancer activity in vitro demonstrated that the anticancer activity of VB was significantly enhanced by the encapsulation of SLNs and pSLNs due to the increased cellular internalization of drug. The results suggested that SLNs and pSLNs could be excellent carrier candidates to entrap VB for tumor chemotherapeutics.

Preparation and characteristics of nanostructured lipid carriers for control-releasing progesterone by melt-emulsification.

Nanostructured lipid carriers (NLC) made from mixtures of solid and spatially incompatible liquid lipids were prepared by melt-emulsification. Their drug loading capacity and releasing properties of progesterone were compared with those of solid lipid nanoparticles (SLN), and the NLC prepared by solvent diffusion method. Monostearin (MS) and stearic acid (SA) were used as solid lipid, whilst the oleic acid (OA) was used as liquid lipid. Properties of carriers such as the particle size and its distribution, drug loading, drug encapsulation efficiency and drug release behavior were investigated. As a result, the drug encapsulation efficiencies were improved by adding the liquid lipid into the solid lipid of nanoparticles. The drug release behavior could be adjusted by the addition of liquid lipid, and the NLC with higher OA content showed the faster rate of drug releasing. NLC had higher efficiency of encapsulation and slower rate of drug release than those of NLC prepared by solvent diffusion method. On the other hand, the NLC with higher drug loading was obtained, though the drug encapsulation efficiency was decreased slightly due to the increase of the amount of drug. The NLC modified with polyethylene glycol (PEG) was also prepared by using polyethylene glycol monostearate (PEG-SA). It was observed that the incorporation of PEG-SA reduced the drug encapsulation efficiency, but increased the rate of drug release. A sample with almost complete drug release in 24h was obtained by modifying with 1.30mol% PEG-SA. It indicated that the modified NLC was a potential drug delivery system for oral administration.

Low molecular weight polyethylenimine-conjugated gold nanospheres: a platform for selective gene therapy controlled by near-infrared light.

AIM: Whether PEI2k-HAuNS could promote gene transfection efficiency controlled by near-infrared (NIR) light. MATERIALS & METHODS: This safe nonviral gene delivery system was obtained by conjugating low molecular weight (2 kDa) polyethylenimine (PEI) onto hollow gold nanospheres (PEI2k-HAuNS). Upon NIR laser irradiation, there was a conspicuous increase both in the in vitro and in vivo transfection achieved by the nanocomplexes. Furthermore, a plasmid encoding the tumor suppressor TP53 (pTP53) was applied to test antitumor activity. RESULTS: The enhanced gene transfection efficiency and therapy of PEI2k-HAuNS were achieved via the mediation of an NIR laser compared with the other treatments in vitro and in vivo. CONCLUSION: The application of NIR laser irradiated PEI2k-HAuNS can be used as a promising gene delivery systems in vitro and in vivo.

Shell cross-linked stearic acid grafted chitosan oligosaccharide self-aggregated micelles for controlled release of paclitaxel.

Stearic acid grafted chitosan oligosaccharide (CSO-SA) with different degree of amino substitution (SD) was synthesized by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated coupling reaction. The critical micelle concentration (CMC) of CSO-SA with different SD was about 0.06, 0.04, 0.01 mg/ml, respectively. With the increase of micelle concentration, the micelle size decreased, and the zeta potential increased. On the other hand, with the increase of SD of CSO-SA, the micelle size and zeta potential decreased due to the increased hydrophobic interaction of SA and the reduced free amino groups. To increase the stability of the micelle in vivo and controll drug release, the shells of micelles were cross-linked by glutaraldehyde. By controlling the molar ratio of CSO-SA to glutaraldehyde, the cross-linking of intra-micelle could be reached, and the nanoparticle with smaller size than that of its initial micelle was obtained. Paclitaxel was then used as model drug to incorporate into the micelles, and the surfaces of the micelles were further cross-linked by glutaraldehyde to form drug loaded and shell cross-linked nanoparticles. The effects of drug loading, SD of CSO-SA and cross-link degree on the size, zeta potential, drug entrapment efficiency and in vitro drug release behavior of micelles and its cross-linked nanoparticles were investigated. The higher drug entrapment efficiencies (above 94%) were observed in all case. The charged amounts of drug did not affect the drug release behavior. The drug release rate decreased with the increase of SD of CSO-SA and cross-link degree.

Tetracycline-grafted PLGA nanoparticles as bone-targeting drug delivery system.

PURPOSE: Nanoparticles (NPs) that target bone tissue were developed using poly(lactic-co-glycolic acid) (PLGA) copolymers and tetracycline (TC)-based bone-targeting moieties. These NPs are expected to enable the transport of drugs, such as simvastatin (SIM), for the treatment of osteoporosis. METHODS: The molecular structures of TC-PLGA were validated by (1)H-NMR, and the SIM-loaded NPs were prepared using the solvent emulsification method. The surface properties, cytotoxicity, cellular uptake, cell mineralization, bone targeting potential, and animal pharmacodynamics of the TC-PLGA NPs were evaluated and compared to those of PLGA NPs. RESULTS: It was confirmed that the average particle size of the NPs was approximately 220 nm. In phosphate-buffered saline (PBS, pH 7.4), the SIM-loaded NPs exhibited a cumulative release of up to 80% within 72 hours. An in vitro cell evaluation indicated that the NPs had an excellent cellular uptake capacity and showed great biocompatibility with MC3T3-E1 cells, thereby reducing the cytotoxic effects of SIM. The cell mineralization assay showed that the SIM-loaded NPs induced osteogenic differentiation and mineralized nodule formation in MC3T3-E1 cells, thereby achieving the same effect as SIM. Preliminary findings from in vitro and in vivo bone affinity assays indicated that the TC-PLGA NPs may display increased bone-targeting efficiency compared to PLGA NPs lacking a TC moiety. The use of SIM-loaded TC-PLGA NPs in treating osteoporosis was tested through animal pharmacodynamics analyses performed in ovariectomized rats, and the results suggested that the SIM-loaded TC-PLGA NPs can improve the curative effects of SIM on the recovery of bone mineral density compared to either SIM-loaded PLGA NPs or SIM alone. CONCLUSION: Bone-targeting NPs, which were based on the conjugation of TC to PLGA copolymers, have the ability to target bone. These NPs may be developed as a delivery system for hydrophobic drugs, and they are expected to improve the curative effects of drugs, reduce the administered drug doses, and reduce side effects in other organs.

Specific targeting of A54 homing peptide-functionalized dextran-g-poly(lactic-co-glycolic acid) micelles to tumor cells.

The delivery of chemotherapeutics into tumor cells is a fundamental knot for tumor-target therapy to improve the curative effect and avoid side effects. Here, A54 peptide-functionalized poly(lactic-co-glycolic acid)-grafted dextran (A54-Dex-PLGA) was synthesized. The synthesized A54-Dex-PLGA self-assembled to form micelles with a low critical micelle concentration of 16.79 µg·mL(-1) and diameter of about 50 nm. With doxorubicin (DOX) base as a model antitumor drug, the drug-encapsulation efficiency of DOX-loaded A54-Dex-PLGA micelles (A54-Dex-PLGA/DOX) reached up to 75%. In vitro DOX release from the A54-Dex-PLGA/DOX was prolonged to 72 hours. The A54-Dex-PLGA micelles presented excellent internalization ability into hepatoma cells (BEL-7402 cell line and HepG2 cell line) in vitro, and the cellular uptake of the micelles by the BEL-7402 cell line was specific, which was demonstrated by the blocking experiment. In vitro antitumor activity studies confirmed that A54-Dex-PLGA/DOX micelles suppressed tumor-cell (BEL-7402 cell) growth more effectively than Dex-PLGA micelles. Furthermore, in vivo biodistribution testing demonstrated that the A54-Dex-PLGA micelles had a higher distribution ability to BEL-7402 tumors than that to HepG2 tumors.

[Preparation and characterization of stearic acid-grafted chitosan oligosaccharide polymeric micelles].

AIM: To prepare the micelles of stearic acid-grafted chitosan oligosaccharide and investigate the drug release from micelles. METHODS: Mediated by a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), stearic acid (SA) was covalently attached to chitosan oligosaccharide (CSO), and the graft polymer (CSO-SA) was obtained. The critical aggregation concentration (CAC) of the CSO-SA was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. The effect of various pH dispersed media and concentration of tripolyphosphate sodium (TPP) on the micellar size distribution and zeta-potential measured by light scattering and electrophoretic mobility, was investigated. In buffers of different pH, the release profiles of methotrexate (MTX) from micelles were evaluated. RESULTS: The CAC value of CSO-SA in deionized water was 0.05 g x L(-1). The mean diameter of CSO-SA micelles was 26.7 nm and the zeta potential was (55.9 +/- 0.1) mV. With the increase of TPP concentration, the size and MTX encapsulation of CSO-SA micelles increased, while the zeta-potential decreased. With the decrease of pH value of dispersed media, the size and zeta-potential of CSO-SA micelles increased, and the MTX encapsulation in CSO-SA micelles decreased. While the enhancement of drug release from the micelles was observed. CONCLUSION: The graft polymer of CSO-SA provides polymeric micelles, which possessed a low CAC value in aqueous media. The drug release in vitro from CSO-SA micelles was affected by the pH of delivery media.

Preparation and characteristics of lipid nanoemulsion formulations loaded with doxorubicin.

PURPOSE: Safe and effective lipid nanoemulsion (LNE) formulations for the antitumor delivery of doxorubicin is designed. METHODS: LNEs composed of medium-chain triglyceride, soybean oil, lecithin, and doxorubicin are prepared by a solvent-diffusion method in an aqueous system. The effects of lipid material composition and polyethylene glycol (PEG)ylation on the size, drug encapsulation efficiency, and stability of LNEs are investigated. Based on in-vitro cytotoxicity and cellular uptake tests of A549 (human lung carcinoma) cells, in-vivo biodistribution, antitumor activity, and cardiac toxicity are further examined using nude mouse bearing A549 tumor. RESULTS: The LNE size decreases from 126.4 ± 8.7 nm to 44.5 ± 9.3 nm with increased weight ratio of medium-chain triglyceride to soybean oil from 1:4 to 3:2, whereas the encapsulation efficiency of doxorubicin is slightly reduced from 79.2% ± 2.1% to 71.2% ± 2.9%. The PEGylation of LNE by 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[carboxy(PEG)2000] (DSPE-PEG 2000) does not significantly change the size and drug encapsulation efficiency. Three-month storage at room temperature and lyophilization process does not affect the drug encapsulation efficiency, whereas the size slightly increases to almost 100 nm. The in-vitro drug-release profiles of LNEs suggest that the present formulation can prolong drug release for 48 hours. LNEs can be internalized into tumor cells in vitro and efficiently accumulate in tumor tissues in vivo by passive targeting. Analysis results of in-vitro and in-vivo antitumor activities reveal that doxorubicin-loaded LNE exerts a therapeutic effect similar to that of the commercial Adriamycin. Moreover, the toxicity of doxorubicin, particularly its cardiac toxicity, is reduced. CONCLUSION: The present LNE formulation of doxorubicin can effectively suppress tumor growth and improve the safety of Adriamycin.

Tumor cells-specific targeting delivery achieved by A54 peptide functionalized polymeric micelles.

The delivery of all of administrated chemotherapeutics into tumor cells is an extreme object for tumor targeting therapy to enhance the curative effect and eliminate the side effect. However, until now, the targeting delivery has only partial been realized by passive targeting, which was called "enhanced permeability and retention" effect, and only few targeting delivery system was commercialized. Here, we designed and synthesized a hepatocarcinoma-binding peptide (A54 peptide, which was identified from a phage-display random peptide library) functionalized and PEGylated stearic acid grafted chitosan (A54-PEG-CS-SA) micelles for targeting therapy of doxorubicin. The A54-PEG-CS-SA micelles presented special internalization ability into human hepatoma cells (BEL-7402) when the cells were co-incubated with normal liver cells in vitro, and high distribution ability to liver and hepatoma tissue in vivo. In vitro and in vivo anti-tumor activity results showed that A54-PEG-CS-SA micelles loading doxorubicin treatments suppressed tumor growth more effectively and reduced toxicity compared with commercial adriamycin injection.