European Journal of Pharmaceutics and Biopharmaceutics (v.65, #3)
Fate of micelles and quantum dots in cells
by Dusica Maysinger; Jasmina Lovrić; Adi Eisenberg; Radoslav Savić (pp. 270-281).
Micelles and quantum dots have been used as experimental drug delivery systems and imaging tools both in vitro and in vivo. Investigations of their fate at the subcellular level require different surface-core modifications. Among the most common modifications are those with fluorescent probes, dense-core metals or radionucleids. Cellular fate of several fluorescent probes incorporated into poly(caprolactone)-b-copolymer micelles (PCL-b-PEO) was followed by confocal microscopy, and colloidal gold incorporated in poly 4-vinyl pyridine-PEO micelles were developed to explore micelle fate by electron microscopy. More recently, we have examined quantum dots (QDs) as the next-generation-labels for cells and nanoparticulate drug carriers amenable both to confocal and electron microscopic analyses. Effects of QDs at the cellular and subcellular levels and their integrity were studied. Results from different studies suggest that size, charge and surface manipulations of QDs may play a role in their subcellular distribution. Examples of pharmacological agents incorporated into block copolymer micelles, administered or attached to QD surfaces show how the final biological outcome (e.g. cell death, proliferation or differentiation) depends on physical properties of these nanoparticles.
Keywords: Block copolymer micelles; Quantum dots; Internalization; Stability; Confocal microscopy; Multiple labeling; Fluorescent dyes; Organelles
Fibrin glue system for adjuvant brachytherapy of brain tumors with188Re and186Re-labeled microspheres
by Urs O. Häfeli; Gayle J. Pauer; Jaya Unnithan; Richard A. Prayson (pp. 282-288).
Brain tumors such as glioblastoma reappear in their original location in almost 50% of cases. To prevent this recurrence, we developed a radiopharmaceutical system that consists of a gel applied immediately after surgical resection of a brain tumor to deliver local radiation booster doses. The gel, which strongly adheres to tissue in the treatment area, consists of fibrin glue containing the β-emitters rhenium-188 and rhenium-186 in microsphere-bound form. Such microspheres can be prepared by short (2h or less) neutron activation even in low neutron flux reactors, yielding a mixture of the two β-emitters rhenium-188 ( Emax=2.1MeV, half life=17h) and rhenium-186 ( Emax=1.1MeV, half life=90.6h). The dosimetry of this rhenium-188/rhenium-186 fibrin glue system was determined using gafchromic film measurements. The treatment efficacy of the radioactive fibrin glue was measured in a 9L-glioblastoma rat model. All animals receiving the non-radioactive fibrin glue died within 17±3 days, whereas 60% of the treated animals survived 36 days, the final length of the experiment. Control animals that were treated with the same amount of radioactive fibrin glue, but had not received a previous tumor cell injection, showed no toxic effects over one year. The β-radiation emitting rhenium-188/rhenium-186-based gel thus provides an effective method of delivering high doses of local radiation to tumor tissue, particularly to wet areas where high adhesive strength and long-term radiation (with or without drug) delivery are needed.
Keywords: Brain tumor; Brachytherapy; Fibrin glue; Microspheres; Rhenium radioisotopes
In vitro and in vivo characterization of a combination chemotherapy formulation consisting of vinorelbine and phosphatidylserine
by Murray S. Webb; Sharon Johnstone; Tara J. Morris; Allison Kennedy; Ryan Gallagher; Natashia Harasym; Troy Harasym; Clifford R. Shew; Paul Tardi; Wieslawa H. Dragowska; Lawrence D. Mayer; Marcel B. Bally (pp. 289-299).
The purpose of these studies was to design an intravenous drug formulation consisting of two active agents having synergistic in vitro activity. Specifically, we describe a novel drug combination consisting of a cytotoxic agent (vinorelbine) with an apoptosis-inducing lipid (phosphatidylserine, PS). In vitro cytotoxicity screening of PS and vinorelbine, alone and in combination, against human MDA435/LCC6 breast cancer and H460 lung cancer cells was used to identify the molar ratio of these two agents required for synergistic activity. PS and vinorelbine were co-formulated in a lipid-based system at the synergistic molar ratio and the pharmacokinetic and antitumor characteristics of the combination assessed in mice bearing H460 tumors. The cytotoxicity of the lipid, and the synergy between the lipid and vinorelbine, were specific to PS; these effects were not observed using control lipids. A novel formulation of PS, incorporated as a membrane component in liposomes, and encapsulating vinorelbine using a pH gradient based loading method was developed. The PS to vinorelbine ratio in this formulation was 1/1, a ratio that produced synergistic in vitro cytotoxicity over a broad concentration range. The vinorelbine and PS dual-agent treatment significantly delayed the growth of subcutaneous human H460 xenograft tumors in Rag2M mice compared to the same dose of free vinorelbine given alone or given as a cocktail of the free vinorelbine simultaneously with empty PS-containing liposomes. These studies demonstrate the potential to develop clinically relevant drug combinations identified using in vitro drug–drug interactions combined with lipid-based delivery systems to co-formulate drugs at their synergistic ratios.
Keywords: Combination therapy; Synergy; Phosphatidylserine; Vinorelbine; Drug delivery
In vivo evaluation of a new polymer-lipid hybrid nanoparticle (PLN) formulation of doxorubicin in a murine solid tumor model
by Ho Lun Wong; Andrew Mike Rauth; Reina Bendayan; Xiao Yu Wu (pp. 300-308).
The purpose of this study is to evaluate the in vivo efficacy, unwanted toxicity and loco-regional distribution of a doxorubicin-loaded polymer-lipid hybrid nanoparticle (Dox-PLN) formulation in a murine solid tumor model after intratumoral injection. Dox-PLN were prepared by dispersing Dox in stearic acid and tristearin, with subsequent addition of a novel anionic polymer HPESO (hydrolyzed polymer of epoxidized soybean oil) to enhance the drug incorporation in the lipids. Solid tumors were obtained by injecting EMT6 mouse mammary cancer cells intramuscularly into the hind legs of BALB/c mice. Dox-PLN, blank PLN or surfactant formulations were injected intratumorally (IT) when tumors reached approximately 0.3g. In vivo efficacy of treatment was measured by tumor growth delay (TGD), defined as the delay in time for the tumor to grow to 1.13g relative to the untreated control. Signs of unwanted drug toxicity, the histology and morphology of tumor and heart tissues, and the IT distribution of Dox-PLN after IT treatment were examined or monitored. IT-administered Dox-PLN resulted in 70% and 100% TGD ( p<0.01) for Dox doses of 0.1 and 0.2mg, respectively. Dox-PLN treated tumors developed substantially larger central necrotic regions than the untreated tumors, with Dox-PLN residues extensively distributed among the dead cell debris, suggesting that the anticancer effect of Dox-PLN was mainly a combined result of IT nanoparticle distribution and short-ranged, sustained drug release. Except for two of fifteen mice receiving the higher 0.2mg Dox dose showing transient fur-roughing, all Dox-PLN treated mice showed no signs of toxicity. The present study demonstrates that Dox-PLN possess significant in vivo cytotoxic activity against solid tumors with minimal systemic toxicity. IT administered Dox-PLN have the potential to improve the therapeutic index of loco-regional solid tumor chemotherapy.
Keywords: Abbreviations; Dox; doxorubicin; IT; intratumoral; MMC; mitomycin C; PLN; polymer-lipid hybrid nanoparticles; SLN; solid lipid nanoparticles; TGD; tumor growth delay; TPL; tumor plus legPolymer-lipid hybrid nanoparticles; Doxorubicin; Cancer chemotherapy; In vivo; efficacy
In vivo fate of unimers and micelles of a poly(ethylene glycol)-block-poly(caprolactone) copolymer in mice following intravenous administration
by Jubo Liu; Faquan Zeng; Christine Allen (pp. 309-319).
Methoxy poly(ethylene glycol)- b-poly(caprolactone) (MePEG- b-PCL) copolymers with varying PEG block lengths and a constant PCL block length were synthesized by cationic ring-opening polymerization and used to form nano-sized micelles. Due to their small size and superior in vitro stability, the MePEG5000- b-PCL5000 micelles were selected for further in vitro characterization and an in vivo evaluation of their fate and stability following intravenous (i.v.) administration. Specifically,3H-labelled MePEG5000- b-PCL5000 micelles were i.v. administered to Balb/C mice at copolymer doses of 250, 2 and 0.2mg/kg in order to examine the distribution kinetics of (1) copolymer assembled as thermodynamically stable micelles, (2) copolymer assembled as thermodynamically unstable micelles and (3) copolymer unimers, respectively. Overall, it was found that when the copolymer is assembled as thermodynamically stable micelles the material is effectively restricted to the plasma compartment. Interestingly, the copolymer was found to have a relatively long circulation half-life even when administered at a dose that would likely fall to concentrations below the CMC following distribution. Analysis of plasma samples from this group revealed that even 24h post-administration a significant portion of the copolymer remained assembled as intact micelles. In this way, this study demonstrates that the hydrophobic and semi-crystalline nature of the PCL core imparts a high degree of kinetic stability to this micelle system.
Keywords: Block copolymer micelle; Poly(ethylene glycol)-block-poly(caprolactone); Drug delivery; In vivo; fate; Kinetic stability; Pharmacokinetics; Biodistribution
Solid molecular dispersions of poorly water-soluble drugs in poly(2-hydroxyethyl methacrylate) hydrogels
by Payam Zahedi; Ping I. Lee (pp. 320-328).
The applicability of cross-linked hydrogels in forming solid molecular dispersions to enhance the delivery of poorly soluble drugs has not been fully explored. The purpose of this study is to characterize physicochemical parameters affecting the formation of solid molecular dispersions of poorly water-soluble drugs in poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels and to investigate the effect of storage humidity levels on their physical stability. Samples were prepared by an equilibrium solvent loading process, using diclofenac sodium, piroxicam and naproxen as model drugs. These were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), as well as changes in the physical state during storage under different humidity conditions. The results show that a threshold drug loading level of about 30% exists in these solid molecular dispersions, above which amorphous to crystalline transition may occur. At any given drug loading, the onset of such change in physical state is accelerated at higher relative humidity levels during storage. The presence of hydrogen bonding between the polymer and the drug, as reflected in the observed FTIR band shifts, improves the compatibility between the drug and the polymer. This, together with a decreased mobility in the glassy polymer, helps to retard the crystallization event below the loading threshold. An increase in dissolution rate is also observed from the polymeric solid molecular dispersion as compared with that of the crystalline pure drug. These physicochemical results indicate that solid molecular dispersions based on PHEMA hydrogels can effectively enhance the dissolution and therefore should be potentially useful in improving the oral bioavailability of poorly water-soluble drugs.
Keywords: Solid dispersion; Poly(2-hydroxyethyl methacrylate); Hydrogel; Poorly water-soluble drug; Solubility enhancements; Physicochemical characterization; Storage stability; Effect of relative humidity; Dissolution
Extended release of high p I proteins from alginate microspheres via a novel encapsulation technique
by L.A. Wells; H. Sheardown (pp. 329-335).
Alginate has potential as a matrix for controlled delivery of protein-based drugs that require site-specific long-term delivery. In the current work albumin, lysozyme and chymotrypsin were encapsulated into alginate microspheres using a novel method that involved soaking the microspheres in a protein-containing NaCl solution. This was followed by recrosslinking with calcium chloride. High p I proteins also appeared to physically crosslink the sodium alginate which resulted in more sustained release. Release was affected by the nature of the releasate solution. In TRIS buffered saline, the high p I proteins chymotrypsin and lysozyme showed sustained release lasting over 150h. Release into 0.15% NaCl led to relatively constant release of lysozyme and chymotrypsin over more than 2000h; reduction of the releasate volume lengthened the lysozyme release to greater than 8 months. Released lysozyme was shown to remain active for at least 16 days, in some cases with activity greater than 100% of the active control. This encapsulation technique can therefore be used to rapidly load alginate microspheres with proteins, with high isoelectric point proteins showing particular promise. Furthermore, the interactions between the high p I proteins and the alginate gel could potentially be exploited to generate new protein delivery systems.
Keywords: Alginate; Crosslinking; Protein delivery; Isoelectric point; Lysozyme; Chymotrypsin; Albumin
In vitro release of a water-soluble agent from low viscosity biodegradable, injectable oligomers
by Soroor Sharifpoor; Brian Amsden (pp. 336-345).
Low-molecular-weight poly(ε-caprolactone-co-1,3-trimethylene carbonate) and poly(1,3-trimethylene carbonate) are potential vehicles for the regio-specific delivery of water-soluble agents. In this paper, the characteristics and the mechanism governing the in vitro release of a model water-soluble drug, vitamin B12, from these polymer vehicles were determined. The loading of vitamin B12 was kept to 1 w/w%. The oligomers examined ranged from amorphous, high viscosity to crystalline but low viscosity. The oligomers did not degrade appreciably in vitro. The total fraction of vitamin B12 released increased as the crystallinity of the oligomers decreased, reaching nearly total release only for the completely amorphous oligomers. The rate of release was fastest for the amorphous oligomers and dependent on their viscosity. Inclusion of a more osmotically active agent, trehalose, into the vitamin B12 particles through co-lyophilization resulted in enhanced total fraction released and a faster release rate. The results are consistent with an osmotically driven release mechanism.
Keywords: Vitamin B12; Biodegradable thermoplastic; Injectable; Local delivery; Trimethylene carbonate; ε-Caprolactone; Osmotic release
Effervescent dry powder for respiratory drug delivery
by Leticia Ely; Wilson Roa; Warren H. Finlay; Raimar Löbenberg (pp. 346-353).
The objective of this work was to develop a new type of respiratory drug delivery carrier particle that incorporates an active release mechanism. Spray drying was used to manufacture inhalable powders containing polybutylcyanoacrylate nanoparticles and ciprofloxacin as model substances for pulmonary delivery. The carrier particles incorporated effervescent technology, thereby adding an active release mechanism to their pulmonary route of administration. Effervescent activity of the carrier particles was observed when the carrier particles were exposed to humidity. Gas bubbles caused by the effervescent reaction were visualized by confocal laser scanning microscopy. The images showed that nanoparticles were distributed throughout the gas bubble. For the effervescent formulation the average mass median aerodynamic diameter (MMAD) was 2.17μm±0.42, fine particle fraction (FPF<=5.6μm) was 46.47%±15 and the GSD was 2.00±0.06. The results also showed that the effervescent carrier particles released 56±8% ciprofloxacin into solution compared with 32±3% when lactose carrier particles were used. The mean nanoparticle size did not significantly change upon release when the nanoparticles were incorporated into an effervescent formulation. However, the mean size significantly increased upon release when only lactose was used as carrier particle matrix. In conclusion, effervescent carrier particles can be synthesized with an adequate particle size for deep lung deposition. This opens the door for future research to explore this technology for delivery of a large range of substances to the lungs with possible improved release compared to conventional carrier particles.
Keywords: Effervescent; Inhalable dry powders; Nanoparticles; Pulmonary delivery; Aerosol; Drug delivery; Ciprofloxacin; Spray drying
Effect of preparation conditions on the nutrient release properties of alginate–whey protein granular microspheres
by Lingyun Chen; Muriel Subirade (pp. 354-362).
The effect of preparation conditions on nutrient release from alginate (AL)–whey protein isolate (WPI) granular microspheres obtained by an emulsification/internal cold gelation method was studied by varying WPI/AL ratio, microsphere diameter, total polymer concentration and riboflavin loading. Microsphere size distribution and nutrient encapsulation efficiency (EE) were examined. Riboflavin release profiles were investigated in simulated gastric and intestinal fluids. Values for EE above 80% were obtained for most microspheres, with the notable exceptions of high AL or pure AL. Variations in WPI/AL ratio, granule size and nutrient loading have major impact on nutrient release. Microspheres prepared with a WPI/AL ratio of 8:2, a riboflavin concentration of 1% in the initial aqueous phase and diameters near 94μm retained the vitamin in SGF and released it in SIF. By careful process design, granular microspheres with potential as oral delivery vehicles for bioactive compounds may be developed.
Keywords: Microspheres; Alginate; Whey protein; Oral administration; Nutrient release
In vitro evaluation of the mucoadhesive properties of polysaccharide-based nanoparticulate oral drug delivery systems
by Siwar Chayed; Françoise M. Winnik (pp. 363-370).
Impedance quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) measurements were performed in order to assess the mucoadhesive properties of hydrophobically modified (HM) derivatives of dextran (DEX), with an average molecular weight of 10,000Da, and of hydroxypropylcellulose (HPC), with an average molecular weight of 80,000Da. The measurements involved (1) treatment of a hydrophobic surface with bovine submaxillary gland mucin (BSM) under various pH conditions (2.0–8.0) and (2) treatment of the BSM layer with buffer solutions of the amphiphilic polysaccharides (pH 3.0 and 7.0). Control measurements were carried out with DEX, HPC, and chitosan (CH) used as a model mucoadhesive polymer. All HM-polysaccharides were shown to adsorb onto a BSM layer, the extent of adsorption increasing with increasing hydrophobicity of the samples. Under the same conditions, HPC and CH interacted with the BSM layer, but DEX showed no affinity to BSM. All the results suggest that HM-polysaccharide micellar systems have the potential of enhancing the bioavailability of poorly adsorbed drugs in peroral delivery.
Keywords: Mucoadhesion; Polysaccharides; Peroral drug delivery; Polymeric micelles; Quartz crystal microbalance; Surface plasmon resonance; Hydroxypropylcellulose; Dextran; Chitosan
High-amylose carboxymethyl starch matrices for oral sustained drug-release: In vitro and in vivo evaluation
by T. Nabais; F. Brouillet; S. Kyriacos; M. Mroueh; P. Amores da Silva; B. Bataille; C. Chebli; L. Cartilier (pp. 371-378).
High-amylose corn starch, that contains 70% of amylose chains and 30% of amylopectin, has been used to obtain substituted amylose (SA) polymers. Tablets have been prepared by direct compression, i.e. dry mixing of drug and SA, followed by compression, which is the easiest way to manufacture an oral dosage form. Until now, their controlled-release properties have been assessed only by an in vitro dissolution test. Amylose-based polymers are normally subject to biodegradation by α-amylase enzymes present in the gastrointestinal tract, but matrix systems show no significant degradation of tablets by α-amylase in vitro.High-amylose sodium carboxymethyl starch (HASCA) is an interesting excipient for sustained drug-release in solid oral dosage forms. In addition to the easy manufacture of tablets by direct compression, the results show that in vitro drug-release from an optimized HASCA formulation is not affected by either acidic pH value or acidic medium residence time. In addition, a compressed blend of HASCA with an optimized quantity of sodium chloride provides a pharmaceutical sustained-release tablet with improved integrity for oral administration. In vivo studies demonstrate extended drug absorption, showing that the matrix tablets do not disintegrate immediately. Nevertheless, acetaminophen does not seem to be the most appropriate drug for this type of formulation.
Keywords: Drug delivery; Sustained release; Excipient; Polymer; Tablet; Matrix; Starch; Amylose; In vitro; In vivo
pH-responsive polymeric micelles of poly(ethylene glycol)- b-poly(alkyl(meth)acrylate- co-methacrylic acid): Influence of the copolymer composition on self-assembling properties and release of candesartan cilexetil
by Prashant Satturwar; Mohamad Nasser Eddine; François Ravenelle; Jean-Christophe Leroux (pp. 379-387).
The objective of the present study was to investigate the influence of chemical structure and molecular weight of pH-sensitive block copolymers on their self-assembling properties, the loading and the release of candesartan cilexetil (CDN). Block copolymers of poly(ethylene glycol) and t-butyl methacrylate, iso-butyl acrylate, n-butyl acrylate or propyl methacrylate were synthesized by atom transfer radical polymerization. pH-sensitivity was obtained by hydrolysis of t-butyl groups. The poorly water-soluble drug CDN was incorporated in the micelles and the in vitro drug release was evaluated as a function of pH. The critical aggregation concentration of hydrolyzed copolymers (p Ka=6.2–6.6) was higher compared to the unhydrolyzed ones. Dynamic light scattering studies and atomic force microscopy images revealed uniform size micelles with aggregation numbers ranging from 60 to 160. The entrapment efficiency of CDN was generally found to be above 90%, with drug loading levels reaching ∼20% (w/w). Differential scanning calorimetry studies showed the amorphous nature of entrapped CDN. The release of CDN from pH-sensitive micelles was triggered upon an increase in pH from 1.2 to 7.2. These findings suggest that the PEG- b-poly(alkyl(meth)acrylate- co-methacrylic acid)s can self-assemble to form micelles which exhibit high loading capacities for CDN and release the drug in a pH-dependent fashion.
Keywords: pH-sensitivity; Polymeric micelles; Candesartan cilexetil; Atom transfer radical polymerization; Critical aggregation concentration; Solvent evaporation; Oral delivery; Poly(ethylene glycol)-; b; -poly(alkyl(meth)acrylate-; co; -methacrylic acid); Drug solubilization
A comparison of the effectiveness of cationic polymers poly-l-lysine (PLL) and polyethylenimine (PEI) for non-viral delivery of plasmid DNA to bone marrow stromal cells (BMSC)
by Laura-Lee Farrell; Joel Pepin; Cezary Kucharski; Xiaoyue Lin; Zhenghe Xu; Hasan Uludag (pp. 388-397).
Bone marrow stromal cells (BMSC) represent an important cell phenotype for pursuit of successful gene therapy. Non-viral methods to enable expression of exogenous genes in BMSC will accelerate clinical application of gene therapy, without the concerns associated with the viral means of gene transfer. Towards this end, this study investigated the potential of cationic polymers poly-l-lysine (PLL) and branched polyethylenimine (PEI) as gene carriers for modification of BMSC. Both polymers rapidly (∼30min) condensed a 4.2kb Enhanced Green Fluorescent Protein (pEGFP-N2) plasmid into 100–200nm particles. PLL and PEI were both readily internalized with BMSC with >80% of BMSC exhibiting polymer uptake by flow cytometric analysis. The relative uptake of PEI, however, was significantly higher as compared to the PLL. The majority of the BMSC (>60%) exhibited nuclear presence of the polymers as analyzed by fluorescent microscopy. Although both polymers were able to deliver the pEGFP-N2 into the cells under microscopic evaluation, only a small fraction of the cells (<10%) displayed nuclear localization of the plasmid. Consistent with better uptake, PEI gave a higher delivery of pEGFP-N2 into the BMSC, which resulted in a more sustained expression of the model gene EGFP in short-term (7-day) culture. We conclude that both PLL and PEI readily displayed cellular uptake, but PEI was more effective in delivering plasmid DNA intracellularly, which was likely the underlying basis for a more sustained gene expression.
Keywords: Non-viral gene delivery; Cationic polymers; Bone marrow stromal cells; DNA binding; DNA uptake; Flow cytometry
Design of a bifunctional fusion protein for ovarian cancer drug delivery: Single-chain anti-CA125 core-streptavidin fusion protein
by Welson Wen-Shang Wang; Dipankar Das; Stephen A. McQuarrie; Mavanur R. Suresh (pp. 398-405).
We have developed a universal ovarian cancer cell targeting vehicle that can deliver biotinylated therapeutic drugs. A single-chain antibody variable domain (scFv) that recognizes the CA125 antigen of ovarian cancer cells was fused with a core-streptavidin domain (core-streptavidin-VL-VH and VL-VH–core-streptavidin orientations) using recombinant DNA technology and then expressed in Escherichia coli using the T7 expression system. The bifunctional fusion protein (bfFp) was expressed in a shaker flask culture, extracted from the periplasmic soluble protein, and affinity purified using an IMAC column. The two distinct activities (biotin binding and anti-CA125) of the bfFp were demonstrated using ELISA, Western blot and confocal laser-scanning microscopy (CLSM). The ELISA method utilized human NIH OVCAR-3 cells along with biotinylated bovine serum albumin (B-BSA) or biotinylated liposomes, whereas, the Western blot involved probing with B-BSA. The CLSM study has shown specificity in binding to the OVCAR-3 cell-line. ELISA and Western blot studies have confirmed the bifunctional activity and specificity. In the presence of bfFp, there was enhanced binding of biotinylated antigen and liposome to OVCAR-3 cells. In contrast, the control EMT6 cells, which do not express the CA125 antigen, showed minimal binding of the bfFp. Consequently, bfFp based targeting of biotinylated therapeutic drugs, proteins, liposomes, or nanoparticles could be an alternative, convenient method to deliver effective therapy to ovarian cancer patients. Peritoneal infusion of the bfFp-therapeutic complex could also be effective in locally targeting the most common site of metastatic spread.
Keywords: Bifunctional fusion protein; Recombinant antibody; Ovarian cancer; Universal delivery vector and liposome
Solubilization of an amphiphilic drug by poly(ethylene oxide)- block-poly(ester) micelles
by Sara Elhasi; Reyhaneh Astaneh; Afsaneh Lavasanifar (pp. 406-413).
The purpose of this study was to investigate the solubilization of an amphiphilic drug, i.e, amiodarone (AMI) in methoxy poly(ethylene oxide)- block-poly(ester) micelles of different core structure. The effect of core-forming block structure as well as molecular weight, applied drug to polymer ratios and assembly condition on AMI solubilization; stability of the solubilized formulation upon dilution in phosphate buffer and the hemolytic activity of solubilized AMI against rat red blood cells were assessed and compared to those parameters for the commercial intravenous formulation of AMI. In general, polymeric micelles of different core structure were found to be more efficient in retaining their AMI content upon dilution than surfactant micelles in the commercial formulation of AMI for injection. Micelles with a poly( ε-caprolactone) (PCL) core were more efficient than poly(d,l-lactide) and poly(l-lactide) cores in the solubilization and stabilization of encapsulated AMI within the carrier. Encapsulation of AMI by methoxy poly(ethylene oxide)- block- poly( ε-caprolactone) (MePEO- b-PCL) micelles having higher PCL chains increased the level of AMI solubilization and decreased its hemolytic activity. Compared to O/W emulsion, application of solvent evaporation method led to higher encapsulation efficiency and lower hemolytic activity for AMI in micelles. An increase in the level of AMI added to the co-solvent evaporation process led to an increase in the solubilized AMI levels, but made the formulation more hemolytic. In conclusion, PEO- b-PCL micelles, particularly those with longer PCL chains, were found to be efficient carriers in encapsulating amphiphilic AMI, retaining encapsulated AMI within the carrier and reducing its hemolytic activity.
Keywords: Amiodarone; Polymeric micelles; Solubilization; Amphiphilic drug; Hemolysis
Topical non-invasive gene delivery using gemini nanoparticles in interferon-γ-deficient mice
by Ildiko Badea; Shawn Wettig; Ronald Verrall; Marianna Foldvari (pp. 414-422).
Cutaneous gene therapy, although a promising approach for many dermatologic diseases, has not progressed to the stage of clinical trials, mainly due to the lack of an effective gene delivery system. The main objective of this study was to construct and evaluate gemini nanoparticles as a topical formulation for the interferon gamma (IFN-γ) gene in an IFN-γ-deficient mouse model.Nanoparticles based on the gemini surfactant 16-3-16 (NP16-DNA) and another cationic lipid cholesteryl 3β-(- N-[dimethylamino-ethyl] carbamate) [Dc-chol] (NPDc-DNA) were prepared and characterized. Zetasizer measurement indicated a bimodal distribution of 146 and 468nm average particle sizes for the NP16-DNA ( ζ-potential +51mV) nanoparticles and monomodal distribution of 625nm ( ζ-potential +44mV) for the NPDc-DNA. Circular dichroism studies showed that the gemini surfactant compacted the plasmid more efficiently compared to the Dc-chol. Small-angle X-ray scattering measurements revealed structural polymorphism in the NP16-DNA nanoparticles, with lamellar and Fd3m cubic phases present, while for the NPDc-DNA two lamellar phases could be distinguished. In vivo, both topically applied nanoparticles induced higher gene expression compared to untreated control and naked DNA (means of 0.480 and 0.398ng/cm2 vs 0.067 and 0.167ng/cm2). However, treatment with NPDc-DNA caused skin irritation, and skin damage, whereas NP16-DNA showed no skin toxicity.In this study, we demonstrated that topical cutaneous gene delivery using gemini surfactant-based nanoparticles in IFN-γ-deficient mice was safe and may provide increased gene expression in the skin due to structural complexity of NP16 nanoparticles (lamellar–cubic phases).
Keywords: Interferon-γ; In vivo; Gene delivery; Non-invasive cutaneous therapy; Gemini nanoparticles; Interferon-γ-deficient mice; Polymorphic phase; Cubic phase; Circular dichroism; Small-angle X-ray scattering