Mixed Polymeric Micelles Research Articles

Systematic evaluation of multifunctional paclitaxel-loaded polymeric mixed micelles as a potential anticancer remedy to overcome multidrug resistance.

In this work, a novel FA-TPGS2K copolymer has been synthesized and used it to construct mixed micelles with HDP copolymer to overcome MDR effect. Furthermore, a series in vitro and in vivo evaluations have been made, which supported enough evidences for the efficient delivery of antitumor drug to MDR cells.

Poly(glycerol) Used for Constructing Mixed Polymeric Micelles as T1 MRI Contrast Agent for Tumor-Targeted Imaging.

There was much interest in the development of nanoscale delivery vehicles based on polymeric micelles to realize the diagnostic and therapeutic applications in biomedicine. Here, with the purpose of constructing a micellar magnetic resonance imaging (MRI) contrast agent (CA) with well biocompatibility and targeting specificity, two types of amphiphilic diblock polymers, mPEG-PG(DOTA(Gd))-b-PCL and FA-PEG-b-PCL, were synthesized to form mixed micelles by coassembly. The nanostructure of the resulting micellar system consisted of poly(caprolactone) (PCL) as core and poly(glycerol) (PG) and poly(ethylene glycol) (PEG) as shell, simultaneously modified with DOTA(Gd) chelates and folic acid (FA), which afforded functions of MRI contrast enhancement and tumor targeting. The mixed micelles in aqueous solution presented a hydrodynamic diameter of about 85 nm. Additionally, this mixed micelles exhibited higher r1 relaxivity (14.01 mM-1 S1-) compared with commercial Magnevist (3.95 mM-1 S1-) and showed negligible cytotoxicity estimated by WST assay. In vitro and in vivo MRI experiments revealed excellent targeting specificity to tumor cells and tissue. Furthermore, considerably enhanced signal intensity and prominent positive contrast effect were achieved at tumor region after tumor-bearing mice were intravenously injected with the mixed micelles. These preliminary results indicated the potential of the mixed micelle as T1 MRI CA for tumor-targeted imaging.

Development and Characterization of Lecithin-based Self-assembling Mixed Polymeric Micellar (saMPMs) Drug Delivery Systems for Curcumin.

Self-assembling mixed polymeric micelles (saMPMs) were developed for overcoming major obstacles of poor bioavailability (BA) associated with curcumin delivery. Lecithin added was functioned to enlarge the hydrophobic core of MPMs providing greater solubilization capacity. Amphiphilic polymers (sodium deoxycholate [NaDOC], TPGS, CREMOPHOR, or a PLURONIC series) were examined for potentially self-assembling to form MPMs (saMPMs) with the addition of lecithin. Particle size, size distribution, encapsulation efficacy (E.E.), and drug loading (D.L.) of the mixed micelles were optimally studied for their influences on the physical stability and release of encapsulated drugs. Overall, curcumin:lecithin:NaDOC and curcumin:lecithin:PLURONIC P123 in ratios of 2:1:5 and 5:2:20, respectively, were optimally obtained with a particle size of < 200 nm, an E.E. of >80%, and a D.L. of >10%. The formulated system efficiently stabilized curcumin in phosphate-buffered saline (PBS) at room temperature or 4 °C and in fetal bovine serum or PBS at 37 °C and delayed the in vitro curcumin release. In vivo results further demonstrated that the slow release of curcumin from micelles and prolonged duration increased the curcumin BA followed oral and intravenous administrations in rats. Thus, lecithin-based saMPMs represent an effective curcumin delivery system, and enhancing BA of curcumin can enable its wide applications for treating human disorders.

Mixed Nanosized Polymeric Micelles as Promoter of Doxorubicin and miRNA-34a Co-Delivery Triggered by Dual Stimuli in Tumor Tissue.

Dual stimuli-sensitive mixed polymeric micelles (MM) are developed for co-delivery of the endogenous tumor suppressor miRNA-34a and the chemotherapeutic agent doxorubicin (Dox) into cancer cells. The novelty of the system resides in two stimuli-sensitive prodrugs, a matrix metalloproteinase 2 (MMP2)-sensitive Dox conjugate and a reducing agent (glutathione, GSH)-sensitive miRNA-34a conjugate, self-assembled in a single particle decorated with a polyethylene glycol corona for longevity, and a cell-penetrating peptide (TATp) for enhanced intracellular delivery. The MMP2-sensitivity of the system results in threefold higher cytotoxicity in MMP2-overexpressing HT1080 cells compared to low MMP2-expressing MCF7 cells. Cellular internalization of Dox increases by more than 70% after inclusion of TATp to the formulation. MMP2-sensitive MM also inhibits proliferation and migration of HT1080 cells. Moreover, GSH-sensitive MM allows for an efficient downregulation of Bcl2, survivin, and notch1 (65%, 55%, and 46%, respectively) in HT1080 cells. Combination of both conjugates in dual sensitive MM reduces HT1080 cell viability to 40% and expression of Bcl2 and survivin. Finally, 50% cell death is observed in 3D models of tumor mass. The results confirm the potential of the MM to codeliver miRNA-34a and doxorubicin triggered by dual stimuli inherent of tumor tissues.

Curcumin-carboxymethyl chitosan (CNC) conjugate and CNC/LHR mixed polymeric micelles as new approaches to improve the oral absorption of P-gp substrate drugs

The low oral bioavailability of numerous drugs has been mostly attributed to the significant effect of P-gp-mediated efflux on intestinal drug transport. Herein, we developed mixed polymeric micelles (MPMs) comprised of curcumin-carboxymethyl chitosan (CNC) conjugate, as a potential inhibitor of P-gp-mediated efflux and gastrointestinal absorption enhancer, and low-molecular-weight heparin-all-trans-retinoid acid (LHR) conjugate, as loading material, with the aim to improve the oral absorption of P-gp substrate drugs. CNC conjugate was synthesized by chemical bonding of curcumin (Cur) and carboxymethyl chitosan (CMCS) taking advantage of the inhibition of intestinal P-gp-mediated secretion by Cur and the intestinal absorption enhancement by CMCS. The chemical structure of CNC conjugate was characterized by 1H NMR with a degree of substitution of Cur of 4.52–10.20%. More importantly, CNC conjugate markedly improved the stability of Cur in physiological pH. Cyclosporine A-loaded CNC/LHR MPMs (CsA-CNC/LHR MPMs) were prepared by dialysis method, with high drug loading 25.45% and nanoscaled particle size (∼200 nm). In situ single-pass perfusion studies in rats showed that both CsA + CNC mixture and CsA-CNC/LHR MPMs achieved significantly higher Ka and Peff than CsA suspension in the duodenum and jejunum segments (p < 0.01), which was comparable to verapamil coperfusion effect. Similarly, CsA + CNC mixture and CsA-CNC/LHR MPMs significantly increased the oral bioavailability of CsA as compared to CsA suspension. These results suggest that CNC conjugate might be considered as a promising gastrointestinal absorption enhancer, while CNC/LHR MPMs had the potential to improve the oral absorption of P-gp substrate drugs.

Development and characterization of self-assembling lecithin-based mixed polymeric micelles containing quercetin in cancer treatment and an in vivo pharmacokinetic study

Quercetin (Que) is known to have biological benefits including an anticancer effect, but low water solubility limits its clinical application. The aim of this study was to develop a lecithin-based mixed polymeric micelle (LMPM) delivery system to improve the solubility and bioavailability of Que. The optimal Que-LMPM, composed of Que, lecithin, Pluronic® P123, and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy[poly(ethylene glycol)-2000] in a proportion of 3:1:17.5:2.5 (w/w), was prepared by a thin-film method. The average size, polydispersion index, encapsulating efficiency, and drug loading of Que-LMPM were 61.60±5.02 nm, 0.589±0.198, 96.87%±9.04%, and 12.18%±1.11%, respectively. The solubility of Que in the Que-LMPM system increased to 5.81 mg/mL, compared to that of free Que in water of 0.17–7.7 μg/mL. The Que-LMPM system presented a sustained-release property in vitro. The in vitro cytotoxicity assay showed that the 50% inhibitory concentration values toward MCF-7 breast cancer cells for free Que, blank LMPMs, and Que-LMPMs were >200, >200, and 110 μM, respectively, indicating the nontoxicity of the LMPM carrier, but the LMPM formulation enhanced the cytotoxicity of Que against MCF-7 cells. A cellular uptake assay also confirmed the intake of Que-LMPM by MCF-7 cells. An in vivo pharmacokinetic study demonstrated that Que-LMPMs had higher area under the concentration–time curve and a longer half-life, leading to better bioavailability compared to a free Que injection. Due to their nanosize, core–shell structure, and solubilization potential, LMPMs were successfully developed as a drug delivery system for Que to improve its solubility and bioavailability.

Reversible Interactions of Proteins with Mixed Shell Polymeric Micelles: Tuning the Surface Hydrophobic/Hydrophilic Balance toward Efficient Artificial Chaperones.

Molecular chaperones can elegantly fine-tune its hydrophobic/hydrophilic balance to assist a broad spectrum of nascent polypeptide chains to fold properly. Such precious property is difficult to be achieved by chaperone mimicking materials due to limited control of their surface characteristics that dictate interactions with unfolded protein intermediates. Mixed shell polymeric micelles (MSPMs), which consist of two kinds of dissimilar polymeric chains in the micellar shell, offer a convenient way to fine-tune surface properties of polymeric nanoparticles. In the current work, we have fabricated ca. 30 kinds of MSPMs with finely tunable hydrophilic/hydrophobic surface properties. We investigated the respective roles of thermosensitive and hydrophilic polymeric chains in the thermodenaturation protection of proteins down to the molecular structure. Although the three kinds of thermosensitive polymers investigated herein can form collapsed hydrophobic domains on the micellar surface, we found distinct capability to capture and release unfolded protein intermediates, due to their respective affinity for proteins. Meanwhile, in terms of the hydrophilic polymeric chains in the micellar shell, poly(ethylene glycol) (PEG) excels in assisting unfolded protein intermediates to refold properly via interacting with the refolding intermediates, resulting in enhanced chaperone efficiency. However, another hydrophilic polymer-poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) severely deteriorates the chaperone efficiency of MSPMs, due to its protein-resistant properties. Judicious combination of thermosensitive and hydrophilic chains in the micellar shell lead to MSPM-based artificial chaperones with optimal efficacy.

Development and characterization of lecithin-based self-assembly mixed micellar drug delivery systems for curcumin

Event Abstract Back to Event Development and characterization of lecithin-based self-assembly mixed micellar drug delivery systems for curcumin Ling-Chun Chen1*, Yin-Chen Chen1, Chia-Yu Su1, Wan-Ping Wong1, Ming-Thau Sheu1* and Hsiu-O Ho1 1 Taipei Medical University, College of Pharmacy, Taiwan Curcumin is the active ingredient extracted from the root of Curcuma longa. However, the great therapeutic applications of curcumin are restricted because of its low aqueous solubility, rapid hydrolysis in alkaline media, light instability and hydrophobic character, resulting in poor bioavailability (BA) (only 1% in rats). Mixed polymeric micelle (MPM), which is able to increase the volume of the hydrophobic core by incorporating extra hydrophobic materials providing larger space for hydrophobic drugs to be solubilized, was developed to overcome major obstacles associated with curcumin delivery. Lecithin is a biocompatible surfactant which is an important component of cell membrane and makes drug easily absorbed, and an additional amphiphilic polymer (sodium dedoxycholate (NaDOC), d-alpha tocopheryl polyethylene glycol succinate (TPGS), Cremophor® and Pluronic® series) were added to form MPM. Curcumin-MPM was prepared by thin film method. Briefly, a predetermined ratio of curcumin, lecithin and another polymer (NaDOC, Pluronic® series of F87, F127, F68, L121, F108, and P123, TPGS, and Cremophor® RH40 and ELP) were added into 1 mL of mixed solvent (Methanol/dichloromethane=3/7, v/v) in the round bottom flask. The mixture was shaken and subsequently evaporated by rotary evaporation under reduced pressure to remove solvent and obtain a thin film. Self-assembly of the thin films resulting in micelle formation was formed by adding 1 mL of deionized water and shook the micelle solution gently until the thin film was completely dispersed. Self-assembling curcumin-MPM was evaluated to determine characteristics such as the average particle size and size distribution, encapsulation efficacy [EE] and drug loading [DL]. After formulation optimization, the formulations were curcumin/ lecithin/ NaDOC= 2/1/5 and curcumin/lecithin/Pluronic® P123=5/2/20, with particle size of less than 200 nm, EE of >80%, and DL of >10%. The formulated system efficiently improved the stability of curcumin in PBS at room temperature or 4 ℃, and in FBS or PBS at 37℃, and retarded in vitro curcumin release. In vivo PK studies shows for oral administration, the absolute BA was 3- and 5-fold increased for curcumin-loaded NaDOC and Pluronic® P123 MPM, respectively; for intravenous administration, the absolute BA was 2.32- and 5.73-fold improvement for curcumin-loaded NaDOC MPM and Pluronic® P123 MPM, respectively.Whereas, for native curcumin solution, the level was not detected beyond 24 h and 2 h with oral and intravenous administration. Our results suggested the slow release of curcumin from micelles, reduced degradation, and prolonged duration resulted in the increase of BA in rats regardless of oral or intravenous administration. In conclusion, lecithin-based MPM represented a useful curcumin delivery system, thereby improving the solubility, stability and BA of curcumin. The enhancement of curcumin BA via lecithin-based MPM can bring this natural molecule to the forefront of therapeutic agents which can treat dreadful cancer. Figure1. Plasma concentration-time curves of curcumin after intravenous administration of lecithin-based mixed micelles (NaDOC and Pluronic® P123) and free curcumin (5 mg/kg) to rats. Figure2. Plasma concentration-time curves of curcumin after oral administration of lecithin-based mixed micelles (NaDOC and Pluronic® P123) and free curcumin (100 mg/kg) to rats. NSC 102-2320-B-038 -022 -MY3

Bisdemethoxycurcumin loaded polymeric mixed micelles as potential anti-cancer remedy: Preparation, optimization and cytotoxic evaluation in a HepG-2 cell model

The purpose of this study was to prepare and optimize Pluronic® mixed micelles as nanocarriers for a natural curcumin derivative viz. bisdemethoxycurcumin (BDMC) that can be used in cancer treatment. Different formulations were prepared according to a full-factorial statistical design. Hence, four mathematical models were generated for the responses; particle size, polydispersity index, zeta-potential and entrapment efficiency percentage. The ratio 20%:80% (F68:F127) w:w and utilizing acetone solely in micellar preparation using thin-film hydration scored optimum results regarding the aforementioned responses. In evaluating the cytotoxic effect of these newly prepared BDMC systems on HepG-2 model cancer cells, an IC50 of 0.74μg/ml was obtained which propose polymeric mixed micelles as successful anti-cancer nanocarrier systems.

EGFR-Targeted Polymeric Mixed Micelles Carrying Gemcitabine for Treating Pancreatic Cancer.

The objective of this study was to design GE11 peptide (YHWYGYTPQNVI) linked micelles of poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate-graft-gemcitabine-graft-dodecanol (PEG-b-PCC-g-GEM-g-DC) for enhanced stability and target specificity of gemcitabine (GEM) to EGFR-positive pancreatic cancer cells. GE11-PEG-PCD/mPEG-b-PCC-g-GEM-g-DC mixed micelles showed EGFR-dependent enhanced cellular uptake, and cytotoxicity as compared to scrambled peptide HW12-PEG-PCD/mPEG-b-PCC-g-GEM-g-DC mixed micelles and unmodified mPEG-b-PCC-g-GEM-g-DC micelles. Importantly, GE11-linked mixed micelles preferentially accumulated in orthotopic pancreatic tumor and tumor vasculature at 24 h post systemic administration. GE11-linked mixed micelles inhibited orthotopic pancreatic tumor growth compared to HW12-linked mixed micelles, unmodified mPEG-b-PCC-g-GEM-g-DC micelles, and free GEM formulations. Tumor growth inhibition was mediated by apoptosis of tumor cells and endothelial cells as determined by immunohistochemical staining. In summary, GE11-linked mixed micelles is a promising approach to treat EGFR overexpressing cancers.

Physical characterization and in vivo pharmacokinetic study of self-assembling amphotericin B-loaded lecithin-based mixed polymeric micelles.

To alleviate the inherent problems of amphotericin B (AmB), such as poor water solubility and nephrotoxicity, a novel self-assembling mixed polymeric micelle delivery system based on lecithin and combined with amphiphilic polymers, Pluronic®, Kolliphor®, d-alpha tocopheryl polyethylene glycol succinate, and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy(poly(ethylene glycol)-2000 (DSPE-PEG2K) was developed. An optimal formulation (Ambicelles) composed of AmB:lecithin:DSPE-PEG2K in a 1:1:10 weight ratio was obtained. The particle size, polydispersion index, drug encapsulation efficiency, and drug loading were 187.20±10.55 nm, 0.51±0.017, 90.14%, and 7.51%, respectively, and the solubility was increased from 0.001 to 5 mg/mL. Compared with that of Fungizone®, the bioavailability of Ambicelles administered intravenously and orally increased 2.18- and 1.50-fold, respectively. Regarding the in vitro cytotoxicity, Ambicelles had a higher cell viability than free AmB solution or Fungizone® did. With pretreatment of 50 μg/mL ethanolic extract of Taiwanofungus camphoratus followed by AmB to HT29 colon cancer cells, the 50% inhibitory concentration of AmB solution was 12 μg/mL, whereas that of Ambicelles was 1 μg/mL, indicating that Ambicelles exerted a greater synergistic anticancer effect.

Tri/tetra-block co-polymeric nanocarriers as a potential ocular delivery system of lornoxicam: in-vitro characterization, and in-vivo estimation of corneal permeation

Polymeric micelles that can deliver drug to intended sites of the eye have attracted much scientific attention recently. The aim of this study was to evaluate the aqueous-based formulation of drug-loaded polymeric micelles that hold significant promise for ophthalmic drug delivery. This study investigated the synergistic performance of mixed polymeric micelles made of linear and branched poly(ethylene oxide)-poly(propylene oxide) for the more effective encapsulation of lornoxicam (LX) as a hydrophobic model drug. The co-micellization process of 10% binary systems combining different weight ratios of the highly hydrophilic poloxamers; Synperonic® PE/P84, and Synperonic® PE/F127 and the hydrophobic poloxamine counterpart (Tetronic® T701) was investigated by means of photon correlation spectroscopy and cloud point. The drug-loaded micelles were tested for their solubilizing capacity towards LX. Results showed a sharp solubility increase from 0.0318mg/mL up to more than 2.34mg/mL, representing about 73-fold increase. Optimized formulation was selected to achieve maximum drug solubilizing power and clarity with lowest possible particle size, and was characterized by 1HNMR analysis which revealed complete encapsulation of the drug within the micelles. Further investigations by histopathological and confocal laser studies revealed the non-irritant nature and good corneal penetrating power of the proposed nano-formulation.

The therapeutic effect of methotrexate-conjugated Pluronic-based polymeric micelles on the folate receptor-rich tumors treatment.

The therapeutic effect of methotrexate (MTX)-conjugated Pluronic-based polymeric mixed micelles (F127/P105-MTX) on the folate receptor-overexpressing tumors treatment was investigated in this study. Due to its high structural similarity to folic acid and the high expression of folate receptor in most solid tumors, MTX serves as not only a cytotoxic agent but also a homing ligand. Cellular uptake and the endocytic mechanism studies of MTX-conjugated mixed micelles were performed in folate receptor-rich KBv and folate receptor-deficient A-549 cancer cells. Additionally, the efficacy and safety studies of F127/P105-MTX in KBv tumor-bearing mice were evaluated. Results indicate that F127/P105-MTX significantly enhanced the cellular uptake in KBv cells as compared to that of conventional non-MTX-conjugated mixed micelles. Moreover, the results showed that F127/P105-MTX can be internalized by both caveolae- and clathrin-mediated endocytosis in energy-dependent and folate receptor-dependent manners. The in vitro and in vivo antitumor efficacies of F127/P105-MTX were significantly enhanced in comparison with MTX-entrapped mixed micelles. Furthermore, no acute toxicities to hematological system and major organs have been observed after intravenous administration during the regimen. Therefore, our results suggest that F127/P105-MTX could be an effective and safe nano-drug delivery system for cancer therapy, especially for the folate receptor-rich cancer treatment.

Artificial chaperones based on mixed shell polymeric micelles: insight into the mechanism of the interaction of the chaperone with substrate proteins using Förster resonance energy transfer.

Controlled and reversible interactions between polymeric nanoparticles and proteins have gained more and more attention with the hope to address many biological issues such as prevention of protein denaturation, interference of the fibrillation of disease relative proteins, removing of toxic biomolecules as well as targeting delivery of proteins, etc. In such cases, proper analytic techniques are needed to reveal the underlying mechanism of the particle-protein interactions. In the current work, Förster Resonance Energy Transfer (FRET) was used to investigate the interaction of our tailor designed artificial chaperone based on mixed shell polymeric micelles (MSPMs) with their substrate proteins. We designed a new kind of MSPMs with fluorescent acceptors precisely placed at the desired locations as well as hydrophobic domains which can adsorb unfolded proteins with a propensity to aggregate. Interactions of such model micelles with a donor-labeled protein-FITC-lysozyme, was monitored by FRET. The fabrication strategy of MSPMs makes it possible to control the accurate location of the acceptor, which is critical to reveal some unexpected insights of the micelle-protein interactions upon heating and cooling. Preadsorption of native proteins onto the hydrophobic domains of the MSPMs is a key step to prevent thermo-denaturation by diminishing interprotein aggregations. Reversible protein adsorption during heating and releasing during cooling have been confirmed. Conclusions from the FRET effect are in line with the measurement of residual enzymatic activity.

Pluronic-based functional polymeric mixed micelles for co-delivery of doxorubicin and paclitaxel to multidrug resistant tumor

Although doxorubicin (DOX) and paclitaxel (PTX) are widely used in clinic as chemotherapeutics, both drug substances are found to be glycoprotein P (P-gp) substrates which are liable to develop the multidrug resistance (MDR). Additionally, the use of single chemotherapeutic drug has known limitations such as high toxicity profile due to the relatively high doses and limited regimen of clinical application. To this end, Pluronic P105–DOX conjugate was successfully designed and developed which can be further used as a hydrophobic core to entrap another anti-cancer drug PTX with Pluronic F127 to form the dual drug-loaded mixed micelles (PF–DP) in our study, which would offer great advantages over conventional micelles, including easy fabrication, high loading capacity, and co-delivery of hydrophilic DOX and hydrophobic PTX to achieve synergistic effect of these two drug substances. Results showed that PF–DP possessed a good polydispersity and sustained release profile for both DOX and PTX in vitro. Studies on cellular uptake demonstrated both anti-cancer drugs in PF–DP can effectively accumulate in MDR cancer cells. Furthermore, in vitro cytotoxicity, cell apoptosis and cell cycle arrest studies indicated that PF–DP had better antitumor efficacy in MDR cancer cells compared to those of single-drug loaded micelles. It was also found that PF–DP can suppress the growth of tumor cells more efficiently than single drug formulations at the equivalent drug concentrations, suggesting synergistic effect could be achieved. More importantly, a much stronger antitumor efficacy in MCF-7/ADR tumor-bearing mice was observed in PF–DP group than that of combined administration of free DOX and PTX. Collectively, the dual drug-loaded Pluronic-based functional mixed micelles developed in this study might be a potential nano-drug delivery system for MDR cancer chemotherapy.

Nevirapine loaded Poloxamer 407/Pluronic P123 mixed micelles: Optimization of formulation and in vitro evaluation

An attempt has been made to develop polymeric mixed micelle delivery system using Poloxamer 407 and Pluronic P123 for the encapsulation of an antiretroviral drug, Nevirapine. The stability of formulated mixed micellar system at different ratios (1:2, 1:1 and 2:1) and standard thermodynamic parameters of micellization have been determined from the temperature dependence of the critical micelle concentration. The process of micellization of Poloxamer 407/Pluronic P 123 system has been found to be entropy dominant at low temperatures and enthalpy driven at high temperatures. The amity of the different components of mixed micelles has been explored using Fourier transform infrared spectroscopy, Differential scanning calorimeter and X-ray diffraction studies, which rule out the possibility of any interactions between the drug and excipients. Micropolarity measurements infer that the drug is solubilized in the inner core of mixed micelles. In addition, dialysis method has been employed to determine the entrapment efficiency of all the three formulations. The formulation at 1:1 ratio exhibits high entrapment efficiency along with sustained release of the drug.

Thermosensitive mixed shell polymeric micelles decorated with gold nanoparticles at the outmost surface: tunable surface plasmon resonance and enhanced catalytic properties with excellent colloidal stability

Gold NPs are coupled to the outermost surface of mixed shell polymeric micelles with a PEG/PNIPAM shell, exhibit thermoresponsive surface plasmon resonance, enhanced catalytic properties and excellent colloidal stability.

Study of block copolymer micelles as vehicles for hydrophobic drug Lamotrigine

Abstract: Objective: The objective of the study was to investigate the solubilization of poorly water-soluble drug Lamotrigine in pure & mixed Pluronic polymeric micelles. Method: Two different Pluronic (Pluronic F68, Pluronic L81) were chosen and micelle formulations were prepared by using various drug:polymer ratios and model drug Lamotrigine. Formulations were characterized by critical micellization concentration (CMC) values, cloud point of copolymers, micelle size and size distribution, zeta potential, loading efficiency ,drug release and stability. Result: Mixed micelles(hydrophilic and hydrophobic) also helped to overcome the limitations of monosystem of Pluronic L81 and Pluronic F68. The solubilized drug and salt decreased the cloud point of copolymers. Results show that the solubilization of Lamotrigine enhances with the rise in concentration of block copolymers, negative Gs0 and temperature, but no significant increase was observed with added salt and at a lower pH the drug show highest solubility. Conclusion: Mixed micelles showed fairly high entrapment efficiency, loading capacity and sustained release profile for Lamotrigine, a model hydrophobe than that of plain Pluronic micelles. Key words: Pluronic F68, Pluronic L81,Micelles,Solubilization.

Polymeric micelles for enhanced Photofrin II® delivery, cytotoxicity and pro-apoptotic activity in human breast and ovarian cancer cells

Searching for photodynamic therapy (PDT) - effective nanocarriers which enable a photosensitizer to be selectively delivered to tumor cells with enhanced bioavailability and diminished dark cytotoxicity is of current interest. The main objective of this study is to evaluate newly designed mixed polymeric micelles based on Pluronics P123 and F127 for the improved delivery of Photofrin II(®) (Ph II(®)) to circumvent unfavorable effects overcoming multidrug resistance (MDR) in tumor cells - in breast MCF-7/WT (caspase-3 deficient) and ovarian SKOV-3 (resistant to chemotherapy). Ph II(®)-loaded micelles were obtained and analyzed for size and morphology, solubilization efficiency, physical stability and in vitro drug release. Intracellular uptake, reactive oxygen species (ROS) generation, mitochondrial oxidoreductive potential and proapoptotic activity (TUNEL assay) studies were evaluated in the examined cancer cells. The preliminary biocompatibility characteristics of all nanocarriers was determined by assessment of their hemolytic activity in human erythrocytes and dark toxicity in cancer cells. Dynamic light scattering (DLS) and atomic force microscopy (AFM) confirmed that almost monodisperse, sphere-shaped and nanosized (DH<20 nm) carriers were developed. Biological studies after photodynamic reaction (PDR) with encapsulated Ph II(®) revealed increased ROS level, malondialdehyde (MDA) concentration and protein damage in SKOV-3 and MCF-7/WT cells in comparison to treatment with free Ph II(®). Numerous apoptotic cells were detected after nano-therapy in both cell lines, with observed significant morphological disorders in ovarian cancer cells. In the case of encapsulated Ph II(®) only negligible disruption of human erythrocytes and cancer cells was observed. The obtained biocompatible long-lasting nanocarriers significantly enhance the Photofrin II(®) photodynamic effect and apoptosis in both SKOV-3 and MCF-7/WT cell lines.

Optimization of long circulating mixed polymeric micelles containing vinpocetine using simple lattice mixture design, in vitro and in vivo characterization

The aim of this study was to increase the in vivo mean residence time of vinpocetine after IV injection utilizing long circulating mixed micellar systems. Mixed micelles were prepared using Pluronics L121, P123 and F127. The systems were characterized by testing their entrapment efficiency, particle size, polydispersity index, zeta potential, transmission electron microscopy and in vitro drug release. Simple lattice mixture design was planned for the optimization using Design-Expert® software. The optimized formula was lyophilized, sterilized and imaged by scanning electron microscope. Moreover, the in vivo behavior of the optimized formula was evaluated after IV injection in rabbits. The optimized formula, containing 68% w/w Pluronic L121 and 32% w/w Pluronic F127, had the highest desirability value (0.621). Entrapment efficiency, particle size, polydispersity index and zeta potential of the optimized formula were 50.74±3.26%, 161.50±7.39nm, 0.21±0.03 and −22.42±1.72mV, respectively. Lyophilization and sterilization did not affect the characteristics of the optimized formula. Upon in vivo investigation in rabbits, the optimized formula showed a significantly higher elimination half-life and mean residence time than the market product. Finally, mixed micelles could be considered as a promising long circulating nanocarrier for lipophilic drugs.