Synthesis and evaluation of cationic polymeric micelles as carriers of lumbrokinase for targeted thrombolysis

To achieve targeted thrombolysis, a targeted delivery system of lumbrokinase(LK) was constructed using RGDfk-conjugated hybrid micelles. Based on the specific affinity of RGDfk to glycoprotein complex of GP Ⅱ b/Ⅲ a expressed on the surface of membrane of activated platelet, LK loaded targeted micelles(LKTM) can be delivered to thrombus. The hybrid micelles were composed of polycaprolactone-block-poly(2-(dimethylamino) ethyl methacrylate)(PCL-PDMAEMA), methoxy polyethylene glycol-block-polycaprolactone(mPEG-PCL)and RGDfk conjugated polycaprolactone-block-polyethylene glycol(PCL-PEG-RGDfk). PCLPDMAEMA was synthesized via ring open polymerization(ROP) and atom transfer radical polymerization(ATRP). PCL-PEG-RGDfk was synthesized via ROP and carbodiimide chemistry. The prepared LKTM was characterized by dynamic light scattering(DLS) and transmission electron microscope(TEM). Colloidal stability assay showed the prepared LKTM was stable. Biocompatibility assay was performed to determine the safe concentration range of polymer. The assay of fluorescent distribution in vivo demonstrated that LKTM can be efficiently delivered to thrombi in vivo. Thrombolysis in vivo indicated the thrombolytic potency of LKTM was optimal in all groups. Notably, the laboratory mice treated with LKTM exhibited a significantly shorter tail bleeding time compared to those treated with LK or LK-loaded micelles without RGDfk, which suggested that the targeted delivery of LK using RGDfk-conjugated hybrid micelles effectively reduced the bleeding risk.

pH-sensitive polymeric micelles triggered drug release for extracellular and intracellular drug targeting delivery

Most of the conventional chemotherapeutic agents used for cancer chemotherapy suffer from multidrug resistance of tumor cells and poor antitumor efficacy.Based on physiological differences between the normal tissue and the tumor tissue,one effective approach to improve the efficacy of cancer chemotherapy is to develop pH-sensitive polymeric micellar delivery systems.The copolymers with reversible protonationedeprotonation core units or acid-liable bonds between the therapeutic agents and the micelle-forming copolymers can be used to form pH-sensitive polymeric micelles for extracellular and intracellular drug smart release.These systems can be triggered to release drug in response to the slightly acidic extracellular fluids of tumor tissue after accumulation in tumor tissues via the enhanced permeability and retention effect,or they can be triggered to release drug in endosomes or lysosomes by pH-controlled micelle hydrolysis or dissociation after uptake by cells via the endocytic pathway.The pH-sensitive micelles have been proved the specific tumor cell targeting,enhanced cellular internalization,rapid drug release,and multidrug resistance reversal.The multifunctional polymeric micelles combining extracellular pH-sensitivity with receptor-mediated active targeting strategies are of great interest for enhanced tumor targeting.The micelles with receptor-mediated and intracellular pH targeting functions are internalized via receptor-mediated endocytosis followed by endosomal-pH triggered drug release inside the cells,which reverses multidrug resistance.The pH sensitivity strategy of the polymeric micelles facilitates the specific drug delivery with reduced systemic side effects and improved chemotherapeutical efficacy,and is a novel promising platform for tumor-targeting drug delivery.

Evaluation of Cisplatin-Loaded Polymeric Micelles and Hybrid Nanoparticles Containing Poly(Ethylene Oxide)-Block-Poly(Methacrylic Acid) on Tumor Delivery

Particulate carriers such as polymeric micelles (PMs) and liposomes have been investigated to increase drug accumulation in tumors and reduce distribution to healthy tissues. In this study, we prepared PM and hybrid nanoparticles (HNPs) with poly(ethylene oxide)-block-poly(methacrylic acid) (PEO-b-PMAA) for loading cisplatin, and evaluated cisplatin release, cytotoxicity, and biodistribution in mice. PM composed of PEO-b-PMAA and HNPs composed of egg phosphatidylcholine (EPC)/PEO-b-PMAA at molar ratios of 50/2.8 (HNP-P5) and 50/50 (HNP-P50), respectively, were prepared by a nanoprecipitation method. The sizes of PM, HNP-P5, and HNP-P50 after inclusion of cisplatin were approximately 200, 100, and 55 nm, respectively, and their entrapment efficiencies were approximately 44% - 66%. In the drug-release study, HNP-P5 and HNP-P50 showed reduced release of cisplatin compared with PM. Regarding the cytotoxic assay, HNP-P5 exhibited lower cytotoxicity for mouse Lewis lung carcinoma (LLC) and mouse colon carcinoma Colon 26 cells than PM and HNP-P50. In terms of biodistribution, PM could significantly improve blood circulation and tumor accumulation after intravenous injection into Colon 26 tumor-bearing mice compared with free cisplatin, but HNP-P5 and HNP-P50 did not. EPC in HNPs might be destabilized in the circulation, although it could reduce release of cisplatin in in vitro experiments. This study suggested that polymeric micelles composed of PEO-b-PMAA are a better carrier for cisplatin than hybrid nanoparticles composed of PEO-b-PMAA and EPC.

Preparation of adhesive resveratrol micelles and determination of drug content

Objective:Resveratrol polymer micelles with tissue adhesion were prepared and the content of resveratrol in the micelles was determined by HPLC.Method:The micelle adhesion experiment was carried out by polylysine orifice plate experiment and small animal fluorescence imaging method,and the micelle prescription was optimized to obtain resveratrol micelles with good adhesion.The separation was performed on a Shiseido SPOLAR C18 column(150 mm×4.6 mm,5μm)with methanol-water(42:58)as the mobile phase.The flow rate was 1.0 mL·min^(-1),the detection wavelength was 305 nm,the column temperature was 35℃,and the injection volume was 10μL.Results:Resveratrol micelles prepared with F127 alone had the best adhesion.The peak area and concentration of resveratrol had a good linear relationship in the concentration range of 10~200μg/mL(r=0.9996).The specificity,precision,recovery and stability all met the methodological requirements.Conclusion:In this experiment,resveratrol micelles with tissue adhesion were successfully prepared,and a method for the determination of resveratrol content in micelles was established.The method is accurate,rapid and simple.

Polymeric complex micelle loaded with axially substituted silicon(Ⅳ) phthalocyanine

A novel axially substituted silicon（IV） phthalocyanine, namely di-pyridyloxy axially substituted silicon（IV） phthalocyanine 2 was synthesized and characterized by UV/vis, IR, elemental analysis, MS as well as IH NMR spectroscopy. Hydrophobic 2 was encapsulated by amphiphilic triblock copolymer poly[N^e-（benzyloxycarbonyl-lysine]-poly（ethylene glycol）-poly [N^e-（benzyl oxycarbonyl） （PLL（Z）-b-PEG-b-PLL（Z）） to form hydrophobic 2-loaded polymeric complex micelle （PIC） （2-loaded P/C）. Atom force microscopy （AFM） image showed that 2-loaded PIC formed a spherical nanocarrier with approximately 35-50 nm in diameter. The fluorescence intensity and lifetime of 2-loaded PIC was significantly enhanced bv the incorporation 2 into PIC nanocarrier.

Polyamine-Polymeric Micelle Hybrid Hydrogel: Microscopic Properties of Crosslinkers Affecting Macroscopic Rheological Properties of Hydrogel

We have developed a hybrid hydrogel that is formed from a crosslinkable polymeric micelle and a polyamine. Under optimal conditions, the hydrogel rapidly formed in one second after a crosslinkable polymeric micelle solution was mixed with a polyamine solution. We could change the hydrogel’s gelation properties, such as the storage modulus and gelation time by tuning the molecular weights of block copolymers and by tuning the pH of the dissolving-solvent of the hydrogel’s constituent components. Furthermore, we have clarified here that the structural difference among the micelles acting as crosslinkers can affect the gelation properties of the hydrogel. According to our findings, the hydrogel that was formed from the polymeric micelles possessing a highly packed (i.e., well-entangled or crosslinked) inner core exhibited a higher storage modulus than the hydrogel that was formed from the polymeric micelles possessing a lowly packed structure. Our results demonstrate that a microscopic structural difference among crosslinkers can induce a macroscopic change in the properties of the resulting hydrogels. For medical applications, the hydrogel proposed in the present paper can encapsulate the hydrophobic compounds in crosslinkers (polymeric micelles) so that the hydrogel can be available as the biomaterial for their sustained release.

The polymer micelles and application in tumor targeted therapy system

The current cancer chemotherapy drugs are inefficient and highly toxic,thus selecting the appropriate new forms of cancer treatment has become one of the important tasks.On the basis of domestic and foreign research,the composition,characteristics and main preparation methods of polymeric micelles,particularly the targeted polymeric micelles are illustrated.This review introduces different targeted polymeric micelles used as an anticancer drug carrier.By making use of the inside microenvironment of tumor cells,the preparation of a variety of new polymeric micelles with slight side effects and powerful effect in vitro and vivo,which can achieve effective control of drug release,is promising in application.

Improved Anti-tumor Efficiency against Prostate Cancer by Docetaxel-loaded PEG-PCL Micelles

This study primarily focused on the systematic assessment of both in vitro and in vivo anti-tumor effects of docetaxel-loaded polyethylene glycol（PEG）2000-polycaprolactone（PCL）2600 micelles on hormone-refractory prostate cancer（HRPC）. By using solvent evaporation method, PEG-PCL was chosen to prepare doxetaxel（DTX）-loaded mPEG-PCL micelles（DTX-PMs）, with the purpose of eliminating side effects of the commercial formulation（Tween 80） and prolonging the blood circulation time. The prepared DTX-PMs had an average particle size of 25.19±2.36 nm, a zeta potential of 0.64±0.15 mV, a polydispersity index of 0.56±0.03, a drug loading of（8.72±1.05）%, and an encapsulation efficiency of（98.1±8.4）%. In vitro cytotoxicity studies indicated that DTX-PMs could effectively kill LNCap-C4-2B cells and show a dose- and time-dependent efficacy. The hemolysis test showed that DTX-PMs had less hemocytolysis than the commercial product of Duopafei. A sustained in vitro release behavior and prolonged circulation time in blood vessels were observed in the DTX-PMs. Furthermore, when compared with Duopafei, the DTX-PMs dramatically reduced the prostate specific antigen（PSA） level and tumor growth of prostate tumor-bearing nude mice in vivo. In conclusion, the DTX-PMs can lower systemic side effects, improve anti-tumor activity with prolonged blood circulation time, and will bring an alternative to patients with HRPC.

FORMATION OF FLOWER-LIKE AGGREGATES FROM SELF-ASSEMBLING OF MICELLES WITH PEO SHELLS AND CROSS-LINKED POLYACRYLAMIDE CORES

Amphiphilic block copolymers,poly(ethylene oxide)-b-poly(N-acryloxysuccinimide) (PEO-b-PNAS) with various molecular weights have been successfully synthesized by atom transfer radical polymerization (ATRP) of NAS using functionalized PEO (PEO-Br) as ATRP macroinitiator.The self-assembling of the block copolymers in water,which is a good solvent for PEO and a non-solvent for PNAS.yielded spherical core-shell micelles with PNAS as core and PEO as shell.The cross-linked reaction of oxysuccinimide in PNAS chain...

Micelles as potential drug delivery systems for colorectal cancer treatment

Despite the significant progress in cancer therapy,colorectal cancer(CRC)remains one of the most fatal malignancies worldwide.Chemotherapy is currently the mainstay therapeutic modality adopted for CRC treatment.However,the long-term effectiveness of chemotherapeutic drugs has been hampered by their low bioavailability,non-selective tumor targeting mechanisms,non-specific biodistribution associated with low drug concentrations at the tumor site and undesirable side effects.Over the last decade,there has been increasing interest in using nanotechnology-based drug delivery systems to circumvent these limitations.Various nanoparticles have been developed for delivering chemotherapeutic drugs among which polymeric micelles are attractive candidates.Polymeric micelles are biocompatible nanocarriers that can bypass the biological barriers and preferentially accumulate in tumors via the enhanced permeability and retention effect.They can be easily engineered with stimuli-responsive and tumor targeting moieties to further ensure their selective uptake by cancer cells and controlled drug release at the desirable tumor site.They have been shown to effectively improve the pharmacokinetic properties of chemotherapeutic drugs and enhance their safety profile and anticancer efficacy in different types of cancer.Given that combination therapy is the new strategy implemented in cancer therapy,polymeric micelles are suitable for multidrug delivery and allow drugs to act concurrently at the action site to achieve synergistic therapeutic outcomes.They also allow the delivery of anticancer genetic material along with chemotherapy drugs offering a novel approach for CRC therapy.Here,we highlight the properties of polymeric micelles that make them promising drug delivery systems for CRC treatment.We also review their application in CRC chemotherapy and gene therapy as well as in combination cancer chemotherapy.

低临界胶束浓度PEGMA-b-PCL的制备及其药物缓释性能

以ε-己内酯(ε-CL)为疏水链段、聚乙二醇甲醚甲基丙烯酸酯(PEGMA)为亲水链段、4-氰基-4-[(十二烷基硫烷基硫代羰基)硫烷基]戊醇(CDPA)为可逆加成-断裂链转移(RAFT)试剂、甲苯为溶剂,在N_(2)氛围、80℃、反应24 h的条件下,通过RAFT聚合法制备了两嵌段共聚物(PEGMA-b-PCL)。将其自组装为胶束,作为纳米药物载体用于负载姜黄素(Cur)。采用FTIR、^(1)HNMR、GPC、SEM、DLS对PEGMA-b-PCL进行了表征,测试了胶束载体的载药和释药性能。结果表明,两嵌段共聚物数均相对分子质量范围为1478~7318,其具有较低的临界胶束浓度(在pH=5.0~7.4,范围为0.920~1.600 mg/L)。胶束载体粒径范围为68.34~186.93 nm。当n(CDPA)∶n(ε-CL)=1∶200时,胶束载药率和包封率最高,可达12.05%±0.29%和75.26%±2.41%。在不同pH环境下,药物缓释性能可达15 d,其中pH=5.0时的累积释药率最高,可达38.20%。

聚合物胶束在纳米载药体系的应用研究进展

聚合物胶束具有能使难溶性药物有效增溶、粒径小、制备方法简单多样等独特优势,作为癌症诊疗的新型药物递送系统已引起广泛关注,但聚合物胶束的临床应用较少。介绍了聚合物胶束的制备和表征方法,综述了聚合物胶束在癌症治疗中的有效性及聚合物胶束制剂的临床应用,指出了其在临床应用中面临的挑战。

Preparation and Characterization of Polymeric Micelles from Poly (D, L-lactide) and Methoxypolyethylene Glycol Block Copolymers as Potential Drug Carriers

Amphiphilic diblock copolymers composed of methoxy polyethylene glycol （MePEG） and poly（D,L-lactide） （PDLLA） were prepared for the preparation of polymeric micelles, The use of MePEG-PDLLA as drug carriers has been reported in the open literature, but there are only few data on the application of a series of MePEG-PDLLA copolymers with different lengths in the medical field, The shape of the polymeric micelles is also important in drug delivery, Studies on in vitro drug release profiles require a good sink condition. The critical micelle concentration of a series of MePEG-PDLLA has a significant role in drug release. To estimate their feasibility as a drug carrier, polymeric micelles made of MePEG-PDLLA block copolymer were prepared by the oil in water （O/VV） emulsion method. From dynamic light scattering （DLS） measurements, the size of the micelle formed was less than 200 nm, The critical micelle concentration of polymeric micelles with various compositions was determined using pyrene as a fluorescence probe. The critical micelle concentration decreased with increasing number of hydrophobic segments. MePEG-PDLLA micelles have a considerably low critical micelle concentration （0.4～0.5 μg/mL）, which is apparently an advantage in utilizing these micelles as drug carriers. The morphology of the polymeric micelles was observed using scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, The micelles were found to be nearly spherical. The yield of the polymeric micelles obtained from the O/W method is as high as 85%.

An overview of polymeric nanomicelles in clinical trials and on the market

Polymeric nanomedicine is a promising and rapidly evolving field.Among the different polymeric carriers,polymeric micelle(PM) with nanoscale size exhibit potent physical and biological advantages including excellent solubility and pharmacokinetics,enhanced efficacy and lower toxicity.PM has garnered increasing intere st in research and in the clinic.This review will highlight the clinical outcomes of several PM-based formulations,and further summarized their preparation methods,strengths and challenges.

EFFECT OF SURFACE CHARGE OF POLYMERIC MICELLES ON IN VITRO CELLULAR UPTAKE

This work focuses on the interaction between polymeric micelles with different charged surfaces and cancer cells in order to study the influence of surface charge on the in vitro cellular uptake efficiency. The amphiphilic diblock copolymers poly（e-caprolaetone）-b-poly（ethylene oxide） （PCL-b-PEO） with different functional groups at the end of hydrophilic block were synthesized. The functional groups endue the micelles with different charges on the surfaces. The cellular uptake of micelles to T-24 cells （human bladder tumor cells）, HepG2 cells （human liver hepatocellular carcinoma cell line） and Hela cells （human epithelial cervical cancer cells） was studied by means of flow cytometer and confbcal laser scanning microscopy. The results indicate that the surface charges showed great influence on zeta potential of micelles at different pH values. The in vitro cellular uptake efficiency of micelles with different charged surfaces demonstrated different cellular uptake patterns to three kinds of cancer cells.

Controlling Drug Release from Titania Nanotube Arrays Using Polymer Nanocarriers and Biopolymer Coating

Titania nanotube arrays (TNT) prepared by self-ordering electrochemical anodization have attracted considerable attraction for the development of new devices for local drug delivery applications. Two approaches to extend drug release of water insoluble drugs by integration TNTs with polymeric micelles and biopolymer coatings are presented in this work. The proposed strategies emphasized on remarkable properties of these materials and their unique combination to design local drug delivery system with advanced performance. The first concept integrates TNTs with drug loaded polymeric micelles (Pluronic F127) as drug nanocarrier, until the second concept includes polymer coating of drug loaded TNT with biodegradable polymer (chitosan). The water insoluble, anti-inflammatory drug, indomethacin was used as a model drug. Both approaches showed a significant improvement of the drug release characteristics, with reduced burst release (from 77% to 39%) and extended overall release from 9 days to more than 28 days. These results suggest the capability of TNT based systems to be applied for local drug delivery deliver over an extended period with predictable kinetics that is particularly important for bone implant therapies.

p-Hydroxybenzoic acid (p-HA) modified polymeric micelles for brain-targeted docetaxel delivery

Chemotherapies for brain diseases have been hampered due to the inability of transport of drug across the blood-brain barrier (BBB). In order to overcome the barrier, p-hydroxybenzoic acid (p-HA), a small molecule of benzamide analogue, was used as a ligand for brain-targeted drug delivery. The p-HA was conjugated to PEG-DSPE to form p-HA-PEG-DSPE. Docetaxel-loaded polymeric micelles were prepared by a thin-film hydration method using methoxy-poly(ethylene glycol)-distearoylphosphatidyl- ethanolamine (mPEG 2000 -DSPE) as a carrier and the p-HA-PEG-DSPE as a brain targeted material. The prepared micelles showed spherical with a mean diameter of (18±3) nm. Encapsulation efficiency and drug loading were (83.49±1.3)%, (7.7±1.2)% for un- modified micelles and (80.65±1.6)%, (7.47±1.8)% for p-HA-modified micelles, respectively. In vitro cellular uptake experiments showed that the p-HA-modified micelles increased BCECs cellular uptake by 1.2 times compared to the unmodified micelles. Ex vivo near-infrared fluorescence imaging showed that brain uptake of the p-HA-modified micelles was 1.3-1.8 times higher than that of the unmodified micelles. In vitro cytotoxicity assay against glioblastoma cell U87 MG showed that inhibition rate of the p-HA-modified micelles increased by 1.2 times compared to that of the unmodified micelles and 1.7 times compared to that of DTX. Survival time of nude mice bearing intracranial glioblastoma showed that the lifetime of saline group, Taxotere group, mPEG-DSPE/DTX micelles group and p-HA-PEG-DSPE/DTX micelles group was 22, 27, 32 and 45.8 d, representively, which indicated that anti-glioblastoma activity of DTX could be significantly enhanced by the p-HA-modified polymeric micelles. These results demonstrated that the p-HA-modified micelles could be a promising brain-targeted drug delivery system for hydrophobic drugs against glioblastoma.

Gambogic acid-encapsulated polymeric micelles improved therapeutic effects on pancreatic cancer

Gambogic acid(GA) is a natural product with potent anticancer activity in vitro. However, poor water solubility and systematic toxicity limit the further clinical application of GA. Micellization of hydrophobic molecule could effectively ameliorate aqueous dispersity of GA and induce better blood retention and tumor accumulation, hence lead to improved stability and therapeutic effect of GA. In this study, monomethyl poly(ethylene glycol)-poly(ε-caprolactone)-poly(trimethylene carbonate)(MPEG-P(CL-ran-TMC)) was used to encapsulate GA by a single-step solid dispersion method to form a GA encapsulated MPEG-P(CLran-TMC) micelles(GA micelles). GA micelles were characterized with a small particle size(44 ±1 nm),high drug loading content(26.28% ± 0.12%) and high-efficiency encapsulation(87.59% ± 0.41 %). Compared with free GA, GA micelles showed better dispersion in water, prolonged release behavior in vitro, and enhanced tumor cellular uptake. GA micelles could also effectively induce apoptosis in AsPC-1 cells.Compared with free GA, GA micelles exhibited superior antitumor efficacy and better apoptosis induced effect in a subcutaneous xenograft mouse model of AsPC-1 cells. In conclusion, GA micelles which showed high-efficiency anti-tumor effect in vitro and in vivo may serve as a candidate for pancreatic cancer therapy.

Enhancement of Formation of Polar Microenvironment in Polymer by Compressed CO_(2)

The copolymer (EO)22(PO)52(EO)22 in p-xylene can solubilize much more water in the presence of compressed CO2 than the case without CO2.

Single-Metal-Atom Polymeric Unimolecular Micelles for Switchable Photocatalytic H_(2) Evolution

Developing“green”catalytic systems with desirable performance such as good water solubility,recyclability,and switchability is a great challenge.Here,to address this challenge,we extend the concept of polymeric unimolecular micelles(a typical selfassembled structure)to the construction of a stimuli-responsive and recoverable molecular catalyst with single-metal atoms that exhibits switchable photocatalytic activity for water splitting.