β-Elemene-loaded polymeric micelles intensify anti-carcinoma efficacy and alleviate side effects

β-Elemene is a volatile oil used for the treatment of cancer,but poor solubility,low bioavailability,and various adverse reactions limit its application.For amelio rating risks of the venous toxicity ofβ-elemene,intravenously injectable micelle ofβ-elemene was prepared using the thin-film hydration method.The results pointed out the micelles were uniformly spherical with about 20.96±0.1966 nm in average diameter and exhibited high entrapment efficiency(99.02%±0.88%).As revealed by drug release studies in vitro,β-elemene micelles had sustained drug release.Compared with freeβ-elemene,the micelles increased the drug cellular uptake and enhanced the anti-tumor effect in vitro through retarding cell cycle and inducing apoptosis.Meanwhile,the elevated se rum stability o fβ-elemene micelles implied less drug leakage and reduced toxicity.The wound healing and tube formation assay in vitro demonstrated the anti-metastasis and anti-angiogenesis effects ofβ-elemene micelles.Moreover,the pharmacokinetics study showed the AUC and T1/2 ofβ-elemene in micelle group were 1.79 and 1.62 times of that in free fi-elemene group,suggesting the circulation time ofβ-elemene in the blood had been prolonged.In addition,β-elemene micelles showed a favorable antitumor response compared with theβ-elemene solution on C26 colon cance r-bearing mice model.Local irritation study investigated in rabbits indicated that theβ-elemene micelles strikingly mitigated the irritation to the injection sites compared with freeβ-elemene.These results proved that the micelle could be a good candidate as an auspicious drug delivery system ofβ-elemene for the prospective clinical treatment of carcinoma.     

Histology and antitumor activity study of PTX-loaded micelle,a fluorescent drug delivery system prepared by PEG-TPP

We synthesized PEG-TPP as carrier to encapsulate paclitaxel(PTX) in the form of micelles to overcome its water-solubility problem. PTX-loaded micelles possess a-week stability and appropriate particle size(152.1 ±1.2 nm) which is beneficial for enhanced permeability and retention(EPR) effect. Strong pH dependence of PTX releasing from micelles is verified by in vitro release study. At cellular level, PTXloaded micelles can target mitochondria effectively which may results a better cytotoxicity of micelles(especially IC50= 0.123 ± 0.035 mmol/L of micelles and 0.298 ± 0.067 mmol/L of PTX alone on MCF-7 cells). The fluorescence distributions of both isolated and sliced organs show that the micelles can effectively target tumors. Moreover, we further prove the enhanced therapeutic effects of micelles in tumor-bearing mice comparing with PTX alone. The results show that the biodegradable drug delivery system prepared by PEG-TPP can overcome the poor solubility of paclitaxel and improve its tumor targeting and antitumor activity.     

Enhanced DOX loading in star-like benzyl functionalized polycaprolactone micelles

The self-assembly of functionalized polycaprolactone amphiphilic diblock copolymers is explored for carrier-mediated doxorubicin delivery for cancer treatment. In this report, functionalized polycaprolactone-based amphiphilic block copolymers with controlled branching architecture are investigated. Star-like copolymers, namely 4-arm and 6-arm poly(γ-benzyloxy-ε-caprolactone)-b-poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-ε-caprolactone} (PBCL-b-PMEEECL) were synthesized by living ring-opening block copolymerization (ROP) of γ-(2-benzyloxy)-ε-caprolactone and γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-ε-caprolactone using multifunctional initiators. A systematic investigation of the effect of branching points on polymer properties and micellar carrier properties was carried out. The star-like PBCL-b-PMEEECL micelles displayed better thermodynamic stability, size reduction, and enhanced doxorubicin encapsulation than the linear PBCL-b-PMEEECL. Furthermore, the π–π stacking between the benzyl group of the hydrophobic PBCL core and the doxorubicin, the anti-cancer drug, also increases the stability and loading capacity of the micelles. The star-polymers display tunable thermoresponsivity in the range of 40–42°C. When the DOX-loaded micelles are accumulated in the tumor, the shell of the polymeric micelles dehydrates upon heating (at a temperature above its LCST), causing disassembling of the micelles and releasing of DOX. Compared with DOX-loaded linear and 4-arm micelles, DOX-loaded 6-arm micelles exhibited higher in vitro anti-tumor activity. Thus, the 6-arm benzyl substituted polycaprolactone-based micellar systems are promising candidates for drug delivery applications.     

Influence of a strong polyelectrolyte block on the formation and properties of polymer micelles with a mixed corona

Joint micellization of two amphiphilic diblock copolymers is studied by velocity sedimentation, transmission electron microscopy, electrophoretic mobility measurements, and static light scattering. One of the diblock copolymers is a strong polyelectrolyte (polystyrene-block-poly(N-ethyl-4-vinylpyridinium bromide)), while the second one is a weakly charged or uncharged copolymer (polystyrene-block-poly(acrylic acid) or polystyrene-block-poly(4-vinylpyridine)). It is shown that the mixing of the diblock copolymers in a selective aqueous-organic solvent (DMF-methanol-water) leads to the formation of joint (hybrid) micelles and that the composition of these micelles is close to the composition of the polymer mixture. Micelles consist of an insoluble polystyrene core and a mixed corona composed of blocks of a strong polyelectrolyte and a weakly charged or uncharged copolymer. Aqueous dispersions of mixed micelles are obtained with the use of the dialysis technique, the spherical morphology of the micelles is ascertained, and their three-layered structure is proposed. The nonlinear dependence of the molecular mass of micelles on their composition is found. The decisive effect of electrostatic repulsion between strong polyelectrolyte units on the thermodynamics of micellization and the dispersion stability and molecular-mass characteristics of the mixed micelles is demonstrated.     

Biodegradable thermogel as culture matrix of bone marrow mesenchymal stem cells for potential cartilage tissue engineering

Poly（lactide-co-glycolide）-poly（ethylene glycol）-poly（lactide-co-glycolide）（PLGA-PEG-PLGA） triblock copolymer was synthesized through the ring-opening polymerization of LA and GA with PEG as macroinitiator and stannous octoate as catalyst. The amphiphilic copolymer self-assembled into micelles in aqueous solutions, and formed hydrogels as the increase of temperature at relatively high concentrations（〉 15 wt%）. The favorable degradability of the hydrogel was confirmed by in vitro and in vivo degradation experiments. The good cellular and tissular compatibilities of the thermogel were demonstrated. The excellent adhesion and proliferation of bone marrow mesenchymal stem cells endowed PLGA-PEGPLGA thermogelling hydrogel with fascinating prospect for cartilage tissue engineering.     

Blocking ACAT‐1 Activity for Tumor Therapy with Fluorescent Hyperstar Polymer‐Encapsulated Avasimible

Targeting the distinct cholesterol metabolism of tumor cells is proposed as a novel way to treat tumors. Blocking acyl‐CoA cholesterol acyltransferase‐1 (ACAT‐1) by the inhibitor avasimible (Ava), which elevates intracellular free cholesterol levels, is shown to effectively induce apoptosis. However, Ava faces disadvantages of poor water solubility, a short half‐life, and no capability for fluorescence detection, which have greatly limited its application. Herein, a fluorescent hyperstar polymer (FHSP) is developed to encapsulate Ava to improve its ability to inhibit HeLa cells and K562 cells. The results of this study show that the obtained Ava–FHSP micelles possess a high drug loading capacity of 22.7% and bright green fluorescence. Ava and Ava–FHSP are cytotoxic to both HeLa and K562 cells and cause reductions in cell size, nuclear lysis, and chromatin condensation and hindered proliferation of both cell types by causing S phase cell cycle arrest. Further mechanistic analysis indicates that Ava–FHSP reduces the protein and messenger RNA expression of ACAT‐1 and significantly increases intracellular free cholesterol levels, which can increase endoplasmic reticulum stress and finally cause cell apoptosis. All these results suggest that this fluorescent hyperstar polymer represents a potential therapeutic tumor strategy by changing the cholesterol metabolism of tumor cells.     

Fabrication of biofunctional complex micelles with tunable structure for application in controlled drug release

In acidic solution, complex micelles were formed by diblock copolymers of poly (ethylene glycol)-b-poly (ε-caprolactone) (PEG-b-PCL) and folate-poly (2-(dimethylamino) ethyl methylacrylate)-b-poly (ε-caprolactone) (Fol-PDMAEMA-b-PCL) with a PCL core, a mixed PEG/Fol-PDMAEMA shell. The surface charge of the complex micelles was positive at acidic surroundings for the protonated PDMAEMA. With increasing pH value to 7.4 (above pK _a of PDMAEMA), these micelles could convert into a core-shell-corona (CSC) structure composing a hydrophobic PCL core, a collapsed PDMAEMA shell, and a soluble PEG corona. Compared to core-shell micelles formed by PEG-b-PCL, micelles with CSC structure can prolong degradation by enzyme. Doxorubicin was physically loaded into the PCL core. The drug release rate was pH-dependent. At pH 5.5, complex micelles with core-shell structure showed faster drug release rate, while at pH 7.4, complex micelles gained CSC structure which control the drug release at a lower rate. The multifunctional complex micelles were prepared for enhanced tumor therapy.     

A Self‐Delivery Chimeric Peptide for Photodynamic Therapy Amplified Immunotherapy

In this paper, a self‐delivery chimeric peptide PpIX‐PEG₈‐KVPRNQDWL is designed for photodynamic therapy (PDT) amplified immunotherapy against malignant melanoma. After self‐assembly into nanoparticles (designated as PPMA), this self‐delivery system shows high drug loading rate, good dispersion, and stability as well as an excellent capability in producing reactive oxygen species (ROS). After cellular uptake, the ROS generated under light irradiation could induce the apoptosis and/or necrosis of tumor cells, which would subsequently stimulate the anti‐tumor immune response. On the other hand, the melanoma specific antigen (KVPRNQDWL) peptide could also activate the specific cytotoxic T cells for anti‐tumor immunity. Compared to immunotherapy alone, the combined photodynamic immunotherapy exhibits significantly enhanced inhibition of melanoma growth. Both in vitro and in vivo investigations confirm that PDT of PPMA has a positive effect on anti‐tumor immune response. This self‐delivery system demonstrates a great potential of this PDT amplified immunotherapy strategy for advanced or metastatic tumor treatment.     

Preparation and characterization of m PEG grafted chitosan micelles as 5-fluorouracil carriers for effective anti-tumor activity

The objective of this study was to investigate the potential of methoxy polyethylene glycol（m PEG）grafted chitosan（m PEG-g-CS） to be used as a drug carrier. m PEG-g-CS was successfully synthesized by one-step method with formaldehyde. The substitution degree of m PEG on chitosan was calculated by elemental analysis and was found to be（3.23 0.25）%. m PEG-g-CS self-assembled micelles were prepared by ultrasonic method with the controlled size of 178.5–195.1 nm and spherical morphology. Stable dispersion of the micelles was formed with the zeta potential of 2.3–30.2 m V. 5-Fluorouracil（5-FU）, an anticancer chemotherapy drug, was used as a model drug to evaluate the efficiency of the new drug delivery carrier. The loading efficiency of 5-FU was（4.01 0.03）%, and the drug-loaded m PEG-g-CS self-assembled micelle showed a controlled-release effect. In summary, the m PEG-g-CS self-assembled micelle is proved to be a promising carrier with controlled particle size and controlled-release effect. Therefore, it has great potential for the application as 5-FU carriers for effective anti-tumor activity.     

Layered microcapsules for daunorubicin loading and release as well as in vitro and in vivo studies

Anti‐cancer drug daunorubicin (DNR) was encapsulated in preformed multilayer microcapsules and was applied in tumor treatment by in vitro cell culture and in vivo animal experiments. The microcapsules were fabricated by an alternate deposition of oppositely charged polysaccharides, i.e. chitosan and alginate onto carboxymethyl cellulose (CMC) doped CaCO₃ colloidal particles in a sequential assembly procedure, followed by crosslinking of the capsule shells with glutaraldehyde (GA) and removal of the templates by disodium ethylenediaminetetraacetic acid (EDTA). The as‐prepared microcapsules showed strong ability to induce the positively charged DNR to deposit into the microcapsule interiors. Confocal microscopy and transmission electron microscopy observed homogeneous distribution of the drug within microcapsules. The loaded DNR could be released again, following a diffusion‐controlled model at the initial stage. In vitro experiments demonstrated that the encapsulated DNR can effectively induce the apoptosis of BEL‐7402 tumor cells, as evidenced by various microscopy techniques after acridine orange (AO), Hoechst 33342, and osmium tetraoxide staining. By seeding the BEL‐7402 hepatoma cells into BALB/c/nu mice, tumors were created for the animal experiments. The results showed that the encapsulated DNR had better efficacy than that of the free drug in terms of tumor inhibition in a 4 week in vivo culture period. Copyright © 2007 John Wiley & Sons, Ltd.     

Fabrication of polymeric micelles with core–shell–corona structure for applications in controlled drug release

Thermo-responsive polymeric micelles of poly (ethylene glycol)-b-poly(2-hydroxyethyl methacrylate-g-lactide)-b-poly(N-isopropylacrylamide) (PEG-P(HEMA-PLA)-PNIPAM) with core–shell–corona structure were fabricated for applications in controlled drug release. The graft copolymer of PEG-P(HEMA-PLA)-PNIPAM was self-assembled into core–shell micelles with a densely PLA core and mixed PEG/PNIPAM shells at 25 °C in aqueous media. By increasing the temperature above the lower critical solution temperature of PNIPAM, these core–shell micelles could be converted into core–shell–corona micelles because of the collapse of PNIPAM block on the PLA core as the inner shell and the soluble PEG block stretching outside as the outer corona. Anticancer drug doxorubicin (DOX) was loaded in the polymeric micelles as a model drug. Compared with polymeric micelles formed by liner PEG-b-PLA-b-PNIPAM triblock copolymer, these polymeric micelles exhibited higher loading capacity, and release of DOX from the polymeric micelles with core–shell–corona structure was well-controlled.     

聚乙二醇-聚谷氨酸-聚丙氨酸三嵌段共聚物的合成及其胶束的pH-响应性药物控制释放

通过大分子引发剂ω-胺基-α-甲氧基聚乙二醇引发N-羧基-α-氨基环内酸酐开环聚合和酸性水解制备了一种具有pH-响应性的三嵌段共聚物聚乙二醇-聚谷氨酸-聚丙氨酸(mPEG-PLGA-PLAA).通过核磁共振、ζ-电势、动态光散射、电子显微镜等手段表征了此类三嵌段共聚物的自组装过程及所形成胶束的pH-响应性.使用圆二色谱和红外光谱,分析了胶束结构随环境pH值转变过程中聚氨基酸链段二级结构的变化.以阿霉素作为模型药物,研究了三嵌段共聚物的载药能力和在不同pH条件下的药物释放能力.在碱性条件下,PLGA链段去质子化,链段从疏水性变为亲水性,胶束中间层由于水合作用变得松散,药物释放速率增加;在酸性条件下,PLGA链段质子化,不带电荷,与阿霉素药物分子间的静电相互作用消失.同时,PLGA链段α-螺旋含量增加,形成由链内氢键维持的刚性棒状结构,将链段周围包埋的药物分子"挤出",加速了药物的释放.     

Design of polylactide-grafted copolymeric stabilizer for dispersion polymerization of D,L-lactide

Poly(D,L-lactide) (PDLLA) microspheres with narrow diameter distribution were prepared by dispersion polymerization of D,L-lactide in xylene/heptane (1:2, v/v) using poly(dodecyl methacrylate)-g-poly(D,L-lactide) (PDMA-g-PDLLA) as a dispersion stabilizer. The particle diameters of PDLLA microspheres were controlled from 200 nm to 5 μm by altering the concentration and the graft chain number of PDMA-g-PDLLA. The effect of the copolymer composition on the particle diameter was investigated to clarify an important factor of the copolymer structure for the control of the particle diameter. As a result, it was necessary for anchor block in diblock copolymer as a dispersion stabilizer to have low solubility in the solution rather than the compatibility with particles. Moreover, we confirmed by dynamic light scattering measurement that PDMA-g-PDLLA formed micelles in the solution. In conclusion, it was clarified that PDLLA microspheres with a wide range of particle diameter were prepared due to the different kinetic stability of micelles.     

Fabrication of multifunctional shell cross-linked micelles for targeting drug release

Thermosensitive amphiphilic poly(N-acroyloxysuccinimide)-b-poly(N-isopropylacrylamide)-b-poly(??-caprolactone) triblock copolymer was synthesized via the combination of reversible addition fragmentation chain transfer and ring-opening polymerization techniques. Shell cross-linked micelle (SCL) was further developed by the addition of cystamine as a di-functional cross-linker into the micellar solution. The persistence of regularly spherical shape against media change demonstrated locked micellar structure resulting from sufficient shell cross-linking. The lower critical solution temperature of the resulting SCL micelles was around 38?°C. The in vitro drug release study was carried out to illustrate the temperature-responsive drug release behaviors. To enhance the internalization to tumor cells, transferring (Tf) was further conjugated to the SCL micelles, and endocytosis experiments further confirmed the efficient uptake of Tf-SCL micelles by tumor cells, indicating that the Tf-SCL micelles would be a promising candidate for tumor-targeted drug delivery.     

聚甘油酸-g-胆固醇胶束的制备及药物释放性能研究

以甘油酸为单体,通过本体缩聚制备了水溶性生物降解高分子聚甘油酸,利用聚甘油酸侧基上的羟基固定生物相容性好的疏水性分子胆固醇,通过亲疏水作用自组装形成胶束.以形成的胶束作为载体负载抗肿瘤药物阿霉素,研究了药物的体外释放行为.将肝癌细胞HepG2与载药胶束共培养研究其体外抗肿瘤效果.研究结果表明,聚甘油酸-g-胆固醇共聚物...     

Co-delivery of docetaxel and doxorubicin using biodegradable PEG-PLA micelles for treatment of breast cancer with synergistic anti-tumour effects

Poly(ethylene glycol)-poly(lactic acid) copolymer, prepared by ring opening polymerization, was used as a single platform to co-deliver both hydrophilic doxorubicin and hydrophobic docetaxel (DTX) in a simulated physiological environment. The average size of the negatively charged drug loaded polymeric micelles were found to be 293 nm. The drug loading (%) and encapsulation efficiency (%) were calculated to be 1.21 and 59.0, respectively. The in vitro cytotoxicity test using MCF7 breast cancer cells was conducted using 1 × 10⁴ cells in 10% FBS and 1% antibiotic, and the absorbance of formazan was evaluated at 570 nm. Cell growth inhibition by MTT assay showed viability of 33% of the MCF7 cells after treatment with drug-loaded micelles for 48 h. Controlled release of drugs from the polymeric micelles indicated a burst release effect initially; whereas, 98% of drug could be released at pH 7.4 within a time period of 96 h. Time period for drug release shorten to 48 h only in simulated mild acidic pH (5.4) condition. The in vitro drug release study from micelles indicated synergistic cytotoxicity effect in human metastatic breast cancer MCF7 cell.     

Zwitterionic heterogemini surfactants containing ammonium and carboxylate headgroups 2: aggregation behavior studied by SANS, DLS, and cryo-TEM

Metallo-meso-5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrins (metallo-TPPSs), such as ZnTPPS, have been widely used as photosensitizers. However, their vulnerability to photodegradation significantly limits their applications. In this contribution, we demonstrate a method to enhance the photostability of metallo-TPPSs while retaining photoactivity via encapsulation inside cores of complex micelles. Poly(ethylene glycol)-b-poly(4-vinylpyridine) (PEG-b-P4VP) and metallo-TPPSs can form complex micelles in acidic solution through electrostatic interactions and then undergo axial coordination with the pyridine moieties of PEG-b-P4VP when the pH is adjusted to 7.4. In this way, metallo-TPPSs are entrapped in the hydrophobic, compact micellar cores, which effectively prevents photodegradation of the metallo-TPPSs that would otherwise occur in aqueous solution. In addition, the photodebromination of 2,3-dibromo-3-phenylpropionic acid (DPP) sensitized with ZnTPPS has been used as a model reaction to study the photosensitive activity of ZnTPPS entrapped in complex micelles. The entrapped ZnTPPSs exhibit pronounced activity and have much higher efficiency and faster photosensitive reaction rates than free ZnTPPS.     

Synthesis,Characterization, In Vitro Anticancer Potentiality,and Antimicrobial Activities of Novel Peptide–Glycyrrhetinic-Acid-Based Derivatives

Glycyrrhetinic acid (GA) is one of many interesting pentacyclic triterpenoids showing significant anticancer activity by triggering apoptosis in tumor cell lines. This study deals with the design and synthesis of new glycyrrhetinic acid (GA)–amino acid peptides and peptide ester derivatives. The structures of the new derivatives were established through various spectral and microanalytical data. The novel compounds were screened for their in vitro cytotoxic activity. The evaluation results showed that the new peptides produced promising cytotoxic activity against the human breast MCF-7 cancer cell line while comparing to doxorubicin. On the other hand, only compounds 3, 5, and 7 produced potent activity against human colon HCT-116 cancer cell line. The human liver cancer (HepG-2) cell line represented a higher sensitivity to peptide 7 (IC₅₀; 3.30 μg/mL), while it appeared insensitive to the rest of the tested peptides. Furthermore, compounds 1, 3, and 5 exhibited a promising safety profile against human normal skin fibroblasts cell line BJ-1. In order to investigate the mode of action, compound 5 was selected as a representative example to study its in vitro effect against the apoptotic parameters and Bax/BCL-2/p53/caspase-7/caspase-3/tubulin, and DNA fragmentation to investigate beta (TUBb). Additionally, all the new analogues were subjected to antimicrobial assay against a panel of Gram-positive and Gram-negative bacteria and the yeast candida Albicans. All the tested GA analogues 1–8 exhibited more antibacterial effect against Micrococcus Luteus than gentamicin, but they exhibited moderate antimicrobial activity against the tested bacterial and yeast strains. Molecular docking studies were also simulated for compound 5 to give better rationalization and put insight to the features of its structure.     

Small-angle neutron scattering and theoretical investigation of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) stabilized oil-in-water microemulsions

The aim of this study is to determine the effects of oil solutes and alcohol cosolvents on the structure of oil-in-water microemulsions stabilized by poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers. The systems investigated involved the solubilization of 1,3,5-trimethylbenzene or 1,2-dichlorobenzene by P123 (EO(20)-PO(70)-EO(20)) pluronic surfactant micelles in water and water + ethanol solvents. The structures of these swollen micelles were determined by small-angle neutron scattering (SANS). A thermodynamic model was employed to interpret the characterization data. The results of the thermodynamic model for micellization agreed well with the SANS data from samples of micelles swollen by both oils. The model predicted the size of the micelles within 5% accuracy using only one fitting parameter, the micelle polydispersity. Ethanol had significantly different effects on the polymer micelles that contained solubilized oil compared to pure polymer micelles. For pure polymer micelles, the addition of ethanol increased the solubility of the polymer and, therefore, decreased the total volume fraction of micelles, while for polymer-oil aggregates, ethanol tended to have a positive effect on the volume fraction of micelles. SANS results showed that the greatest divergence from pure aqueous solvent results occurred at oil concentrations above the microemulsion stability limit.     

PEO-PPO-PEO水溶液体系胶束化及凝胶化行为的耗散粒子动力学模拟

采用耗散粒子动力学(Dissipative particle dynamics, DPD)模拟方法研究了三嵌段共聚物聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO)的胶束化和凝胶化行为. 通过模拟得到了F127(EO₉₉PO₆₅EO₉₉)水溶液的临界胶束浓度和临界凝胶浓度. 结果发现, 在298 K、 质量分数低于40%时, F127水溶液中形成的胶束形状均为球形. 此外,进一步研究了亲水嵌段长度对胶束结构及凝胶形成浓度的影响, 结果发现, 亲水嵌段越短, 越有利于长椭球状胶束的形成, 而临界凝胶浓度随着亲水嵌段PEO长度的增加而降低.