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Carrier System (carrier + system)
Selected AbstractsDelivery of Nucleic Acids via Disulfide-Based Carrier SystemsADVANCED MATERIALS, Issue 32-33 2009Sonja Bauhuber Abstract Nucleic acids are not only expected to assume a pivotal position as "drugs" in the treatment of genetic and acquired diseases, but could also act as molecular cues to control the microenvironment during tissue regeneration. Despite this promise, the efficient delivery of nucleic acids to their side of action is still the major hurdle. One among many prerequisites for a successful carrier system for nucleic acids is high stability in the extracellular environment, accompanied by an efficient release of the cargo in the intracellular compartment. A promising strategy to create such an interactive delivery system is to exploit the redox gradient between the extra- and intracellular compartments. In this review, emphasis is placed on the biological rationale for the synthesis of redox sensitive, disulfide-based carrier systems, as well as the extra- and intracellular processing of macromolecules containing disulfide bonds. Moreover, the basic synthetic approaches for introducing disulfide bonds into carrier molecules, together with examples that demonstrate the benefit of disulfides at the individual stages of nucleic acid delivery, will be presented. [source] Bioaccumulation and biotransformation of arsenic in the Mediterranean polychaete Sabella spallanzanii experimental observationsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2007Alessandra Notti Abstract The Mediterranean fan worm Sabella spallanzanii is characterized by elevated basal levels of arsenic in branchial crowns (>1,000 ,g/g) and an unusual prevalence of dimethylarsinic acid (DMA), a relatively toxic compound with a possible antipredatory role. The aim of this work was to obtain further insights on the capability of this polychaete to accumulate arsenic from different compounds and to operate biotransformation reactions. Laboratory exposures to arsenate (AsV), dimethylarsinic acid (DMA), trimethylarsine (TMA), and arsenobetaine (AsB) revealed significant differences among tissues and kind of experiments. The highest increases of arsenic content were observed in branchial crowns of organisms treated with arsenate, which can enter the cell through the phosphate carrier system; lower variations were measured with DMA and TMA, while not-significant changes of total As occurred after treatments with AsB. In body tissues, exposure to AsV, DMA, and TMA confirmed a progressively lower accumulation of total arsenic, while a marked increase was caused by AsB. Obtained results suggested that accumulated arsenic could be chemically transformed, thus explaining the elevated basal levels of DMA typical of S. spallanzanii; during all the experiments, DMA was the most accumulated molecule, suggesting that this species possesses the enzymatic pathways for methylation and demethylation reactions of inorganic and trimethylated arsenicals. Only arsenobetaine was not converted into DMA, which would confirm a microbial pathway for degradation for this molecule, particularly important in body tissues of S. spallanzanii for the presence of bacteria associated to digestive tracts. Overall, the present study suggests future investigations on the biological role of arsenic and DMA in S. spallanzanii as a potential adaptive mechanism against predation in more vulnerable tissues. [source] Synthesis of Magnetic, Up-Conversion Luminescent, and Mesoporous Core,Shell-Structured Nanocomposites as Drug CarriersADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Shili Gai Abstract The synthesis (by a facile two-step sol,gel process), characterization, and application in controlled drug release is reported for monodisperse core,shell-structured Fe3O4@nSiO2@mSiO2@NaYF4: Yb3+, Er3+/Tm3+ nanocomposites with mesoporous, up-conversion luminescent, and magnetic properties. The nanocomposites show typical ordered mesoporous characteristics and a monodisperse spherical morphology with narrow size distribution (around 80,nm). In addition, they exhibit high magnetization (38.0,emu g,1, thus it is possible for drug targeting under a foreign magnetic field) and unique up-conversion emission (green for Yb3+/Er3+ and blue for Yb3+/Tm3+) under 980,nm laser excitation even after loading with drug molecules. Drug release tests suggest that the multifunctional nanocomposites have a controlled drug release property. Interestingly, the up-conversion emission intensity of the multifunctional carrier increases with the released amount of model drug, thus allowing the release process to be monitored and tracked by the change of photoluminescence intensity. This composite can act as a multifunctional drug carrier system, which can realize the targeting and monitoring of drugs simultaneously. [source] Pathogen-Mimicking MnO Nanoparticles for Selective Activation of the TLR9 Pathway and Imaging of Cancer Cells,ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009Mohammed Ibrahim Shukoor Abstract Here, design of the first pathogen-mimicking metal oxide nanoparticles with the ability to enter cancer cells and to selectively target and activate the TLR9 pathway, and with optical and MR imaging capabilities, is reported. The immobilization of ssDNA (CpG ODN 2006) on MnO nanoparticles is performed via the phosphoramidite route using a multifunctional polymer. The multifunctional polymer used for the nanoparticle surface modification not only affords a protective organic biocompatible shell but also provides an efficient and convenient means for loading immunostimulatory oligonucleotides. Since fluorescent molecules are amenable to photodetection, a chromophore (Rhodamine) is introduced into the polymer chain to trace the nanoparticles in Caki-1 (human kidney cancer) cells. The ssDNA coupled nanoparticles are used to target Toll-like receptors 9 (TLR9) receptors inside the cells and to activate the classical TLR cascade. The presence of TLR9 is demonstrated independently in the Caki-1 cell line by western blotting and immunostaining techniques. The magnetic properties of the MnO core make functionalized MnO nanoparticles potential diagnostic agents for magnetic resonance imaging (MRI) thereby enabling multimodal detection by a combination of MR and optical imaging methods. The trimodal nanoparticles allow the imaging of cellular trafficking by different means and simultaneously are an effective drug carrier system. [source] An exhumed palaeo-hydrocarbon migration fairway in a faulted carrier system, Entrada Sandstone of SE Utah, USAGEOFLUIDS (ELECTRONIC), Issue 3 2001I. R. Garden Abstract The Moab Anticline, east-central Utah, is an exhumed hydrocarbon palaeo-reservoir which was supplied by hydrocarbons that migrated from the Moab Fault up-dip towards the crest of the structure beneath the regional seal of the Tidwell mudstone. Iron oxide reduction in porous, high permeability aeolian sandstones records the secondary migration of hydrocarbons, filling of traps against small sealing faults and spill pathways through the Middle Jurassic Entrada Sandstone. Hydrocarbons entered the Entrada Sandstone carrier system from bends and other leak points on the Moab Fault producing discrete zones of reduction that extend for up to 400 m from these leak points. They then migrated in focused stringers, 2,5 m in height, to produce accumulations on the crest of the anticline. Normal faults on the anticline were transient permeability barriers to hydrocarbon migration producing a series of small compartmentalized accumulations. Exsolution of CO2 as local fault seals were breached resulted in calcite cementation on the up-dip side of faults. Field observations on the distribution of iron oxide reduction and calcite cements within the anticline indicate that the advancing reduction fronts were affected neither by individual slip bands in damage zones around faults nor by small faults with sand: sand juxtapositions. Faults with larger throws produced either sand: mudstone juxtapositions or sand: sand contacts and fault zones with shale smears. Shale-smeared fault zones provided seals to the reducing fluid which filled the structural traps to spill points. [source] Delivery of Nucleic Acids via Disulfide-Based Carrier SystemsADVANCED MATERIALS, Issue 32-33 2009Sonja Bauhuber Abstract Nucleic acids are not only expected to assume a pivotal position as "drugs" in the treatment of genetic and acquired diseases, but could also act as molecular cues to control the microenvironment during tissue regeneration. Despite this promise, the efficient delivery of nucleic acids to their side of action is still the major hurdle. One among many prerequisites for a successful carrier system for nucleic acids is high stability in the extracellular environment, accompanied by an efficient release of the cargo in the intracellular compartment. A promising strategy to create such an interactive delivery system is to exploit the redox gradient between the extra- and intracellular compartments. In this review, emphasis is placed on the biological rationale for the synthesis of redox sensitive, disulfide-based carrier systems, as well as the extra- and intracellular processing of macromolecules containing disulfide bonds. Moreover, the basic synthetic approaches for introducing disulfide bonds into carrier molecules, together with examples that demonstrate the benefit of disulfides at the individual stages of nucleic acid delivery, will be presented. [source] Biodistribution characteristics of all- trans retinoic acid incorporated in liposomes and polymeric micelles following intravenous administrationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2005Shigeru Kawakami Abstract The aim of this study was to investigate the biodistribution characteristics of all- trans retinoic acid (ATRA) incorporated in liposomes and polymeric micelles following intravenous administration. [3H] ATRA were incorporated in distearoylphosphatidylcholine (DSPC)/cholesterol (6:4) liposomes. Two types of block copolymers, poly (ethylene glycol)-b-poly-(aspartic acid) derivatives with benzyl (Bz-75) groups, were synthesized to prepare the polymeric micelles for [3H]ATRA incorporation. ATRA were dissolved in mouse serum to analyze their inherent distribution. After intravenous administration, the blood concentration of [3H] ATRA in liposomes and polymeric micelles (Bz-75) was higher than that of inherent [3H]ATRA, suggesting that liposomes and polymeric micelles (Bz-75) control the distribution of ATRA. Pharmacokinetic analysis demonstrated that [3H]ATRA incorporated in polymeric micelles (Bz-75) exhibit the largest AUCblood and lowest hepatic clearance of ATRA, suggesting that polymeric micelles (Bz-75) are an effective ATRA carrier system for acute promyelocytic leukemia (APL) therapy. These results have potential implications for the design of ATRA carriers for APL patients. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:2606,2615, 2005 [source] Chitosan-coated antifungal formulations for nebulisationJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2010Yacoub Y. Albasarah Abstract Objectives, The aim of this study was to produce and characterise amphotericin B (AmB) containing chitosan-coated liposomes, and to determine their delivery from an air-jet nebuliser. Methods, Soya phosphatidylcholine : AmB (100 : 1) multilamellar vesicles were generated by dispersing ethanol-based proliposomes with 0.9% sodium chloride or different concentrations of chitosan chloride. These liposomes were compared with vesicles produced by the film hydration method and micelles. AmB loading, particle size, zeta potential and antifungal activity were determined for formulations, which were delivered into a two-stage impinger using a jet nebuliser. Key findings, AmB incorporation was highest for liposomes produced from proliposomes and was greatest (approximately 80% loading) in chitosan-coated formulations. Following nebulisation, approximately 60% of the AmB was deposited in the lower stage of the two-stage impinger for liposomal formulations, for which the mean liposome size was reduced. Although AmB loading in deoxycholate micellar formulations was high (99%), a smaller dose of AmB was delivered to the lower stage of the two-stage impinger compared to chitosan-coated liposomes generated from proliposomes. Chitosan-coated and uncoated liposomes loaded with AmB had antifungal activities against Candida albicans and C. tropicalis similar to AmB deoxycholate micelles, with a minimum inhibitory concentration of 0.5 µg/ml. Conclusions, This study has demonstrated that chitosan-coated liposomes, prepared by an ethanol-based proliposome method, are a promising carrier system for the delivery of AmB using an air-jet nebuliser, having a high drug-loading that is likely to be effectively delivered to the peripheral airways for the treatment of pulmonary fungal infections. [source] Supramolecular Structures Generated by Spherical Polyelectrolyte Brushes and their Application in CatalysisMACROMOLECULAR RAPID COMMUNICATIONS, Issue 9-10 2009Yan Lu Abstract We survey recent studies on composite particles made from spherical polyelectrolyte brushes (SPB) and catalytically active nanoparticles or enzymes. SPB consist of a solid core (diameter: ca. 100 nm) onto which long chains of anionic or cationic polyelectrolyte (PE) are densely grafted ("PE brush"). Immersed in water the PE layer affixed to the colloidal core will swell due to the enormous osmotic pressure of the confined counterions ("osmotic brush"). This confinement of the counterions can be used to generate metal nanoparticles on the surface of the SPB. Moreover, enzymes can be immobilized within the PE layer. In both cases, the resulting composite particles are stable against coagulation and can be easily handled and filtered off. The catalytic activity of both systems is largely preserved in case of the enzymes, in case of the metal nanoparticles it is even enhanced. Thus, the SPB present an excellent carrier system for applications in catalysis. [source] The Future of Gaseous Fuels in Hong KongOPEC ENERGY REVIEW, Issue 1 2001Larry Chuen-ho Chow There are three types of gaseous fuel in Hong Kong. Natural gas, exclusively used for power generation and imported under a 20-year contract, accounted for 16 per cent of total primary energy requirements in 1998. Towngas, manufactured from naphtha, and liquefied petroleum gas are the two other kinds, accounting for about 9.5 per cent of the final energy requirement in recent years. The first part of this paper analyses the competition between these two gaseous fuels since 1984, elucidating in detail how towngas came to dominate the gaseous fuel market. The government of the Hong Kong Special Administrative Region would like to boost the use of natural gas in Hong Kong, on account of its environmental benefits and cost competitiveness. It is considering the possibility of using natural gas to replace the other two gaseous fuels and adopting the common carrier system, in order to spur competition in the gaseous fuel market. The second part of the study evaluates the feasibility of converting to natural gas and opening up the pipeline system, putting forth a rough schedule for the whole process. [source] Filling of carbon nanotubes for bio-applicationsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007S. Costa Abstract Carbon nanotubes (CNT) provide a smart carrier system on the nanometer scale. The system can be used as a template for ferromagnetic fillers. Such a molecular hybrid is a promising potential candidate for the controlled heating of tumour tissue at the cellular level. This is a key reason why it is important to optimize the synthesis route of metal filled carbon nanotubes with regards bulk scale synthesis and purity. In the current study we present multiwalled carbon nanotubes filled with ,-iron phase (Fe-MWCNT). The influence of acid treatment on the stability of the filling and the sample purity is also presented. High resolution transmission microscopy, its Energy dispersive X-Ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) modes have been applied for the analysis of the morphology and chemical composition of the samples. The phase of iron nanowires encapsulated into the carbon nanotubes was determined with selected area electron diffraction (SAED) on a local scale. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Flux of Positive Ions and Film Growth in Reactive Sputtering of Al-Doped ZnO Thin FilmsPLASMA PROCESSES AND POLYMERS, Issue S1 2007Florian Ruske Abstract The reactive magnetron sputtering deposition of Al-doped zinc oxide thin films using a dual magnetron has been studied for a flux of positive ions and the total thermal load onto the substrate. The spatial distribution of both quantities has been studied using a thermal probe and a retarding field analyzer mounted onto a moveable carrier system. The positive ions were found to mostly originate from the plasma sheath at the substrate, with the spatial distribution determined by the plasma density distribution in the coating chamber. The total energy flux to the substrate mainly originated from the plasma, with positive ions only contributing a small part of the total plasma irradiation. In the tested conditions and with the coater examined, the quality of the deposited films mainly depends on oxygen distribution on the substrate and is not a direct consequence of the total energy flux to the substrate. [source] Calculation of profile of charge carrier concentration in modulation doped structure with a wide potential wellANNALEN DER PHYSIK, Issue 12 2009L.Yu. Shchurova Abstract We investigate the equilibrium state of interacting electron system with Fermi statistics in modulation doped structure with a wide quantum well. The model is formulated for the carrier system with a sufficiently high density, such that the de Broglie wavelength of electrons is smaller than the width of the quantum well. Due to a significant interaction of electrons with electric field of the doped layer, a state with strongly-inhomogeneous density of electrons is formed. Within the hydrodynamic approach, we set up formalism for calculating the electron density across the width of the potential well. We have obtained the exact solution of the equations, which is expressed in terms of hypergeometric functions. Based on the deduced formulas, we performed numerical computations for the profile of carriers' concentrations in a potential well in the modulation doped Si/SiGe/Si structures. [source] N -Malonyl-1,2-dihydroisoquinoline as a Novel Carrier for Specific Delivery of Drugs to the BrainARCHIV DER PHARMAZIE, Issue 1 2010Mohamed Abdel-Aziz Abstract N -Malonyl-1,2-dihydroisoquinoline derivatives were synthesized and investigated as a novel carrier system for site-specific and sustained delivery of drugs to the brain. Such carriers are expected to be stable against air oxidation due to the presence of the carbonyl group close to nitrogen of the dihydroisoquinoline. Reduction of the prepared isoquinolinium quaternary derivatives with sodium dithionite afforded a novel group of N -malonyl-1,2-dihydroisoquinoline chemical delivery systems (CDS). The synthesized N -malonyl-1,2-dihydroisoquinoline chemical delivery systems were subjected to various chemical and biological investigations to evaluate their ability to cross the blood-brain barrier (BBB), and to be oxidized biologically into their corresponding quaternary derivatives. The in-vitro oxidation studies showed that the designed N -malonyl-1,2-dihydroisoquinoline chemical delivery system could be oxidized into its corresponding quaternary derivatives at an adequate rate. The in-vivo distribution studies showed that these N -malonyl-1,2-dihydroisoquinoline chemical delivery systems were able to cross the blood-brain barrier at detectable concentrations. [source] Amphoteric liposomes enable systemic antigen-presenting cell,directed delivery of CD40 antisense and are therapeutically effective in experimental arthritisARTHRITIS & RHEUMATISM, Issue 4 2009Evangelos Andreakos Objective Mediation of RNA interference by oligonucleotides constitutes a powerful approach for the silencing of genes involved in the pathogenesis of inflammatory disease, but in vivo application of this technique requires effective delivery to immune cells and/or sites of inflammation. The aim of the present study was to develop a new carrier system to mediate systemic administration of oligonucleotides to rheumatoid arthritis (RA) joints, and to develop an antisense oligonucleotide (ASO),based approach to interfere with CD40,CD154 interactions in an experimental model of RA. Methods A novel liposomal carrier with amphoteric properties, termed Nov038, was developed and assessed for its ability to systemically deliver an ASO directed against CD40 (CD40-ASO). Male DBA/1 mice with collagen-induced arthritis were treated with Nov038-encapsulated CD40-ASO, and the effects of treatment on various parameters of disease activity, including clinical score, paw swelling, lymph node responses, and inflammatory cytokine production in the joints, were assessed. Results Nov038 was well tolerated, devoid of immune-stimulatory effects, and efficacious in mediating systemic oligonucleotide delivery to sites of inflammation. In mice with collagen-induced arthritis, Nov038 enabled the therapeutic administration of CD40-ASO and improved established disease, while unassisted CD40-ASO was ineffective, and anti,tumor necrosis factor , (anti-TNF,) treatment was less effective in this model. Nov038/CD40-ASO efficacy was attributed to its tropism for monocyte/macrophages and myeloid dendritic cells (DCs), resulting in rapid down-regulation of CD40, inhibition of DC antigen presentation, and reduction in collagen-specific T cell responses, as well as decreased levels of TNF,, interleukin-6 (IL-6), and IL-17 in arthritic joints. Conclusion Amphoteric liposomes represent a novel carrier concept for systemic and antigen-presenting cell,targeted oligonucleotide delivery with clinical applicability and numerous potential applications, including target validation in vivo and inflammatory disease therapeutics. Moreover, Nov038/CD40-ASO constitutes a potent alternative to monoclonal antibody,based approaches for interfering with CD40,CD40L interactions. [source] Development of a vaccine marker technology: Display of B cell epitopes on the surface of recombinant polyomavirus-like pentamers and capsoids induces peptide-specific antibodies in piglets after vaccinationBIOTECHNOLOGY JOURNAL, Issue 12 2006Markus Neugebauer Abstract Highly immunogenic capsomers (pentamers) and virus-like particles (VLPs) were generated through insertion of foreign B cell epitopes into the surface-exposed loops of the VP1 protein of murine polyomavirus and via heterologous expression of the recombinant fusion proteins in E. coli. Usually, complex proteins like the keyhole limpet hemocyanin (KLH) act as standard carrier devices for the display of such immunogenic peptides after chemical linkage. Here, a comparative analysis revealed that antibody responses raised against the carrier entities, KLH or VP1 pentamers, did not significantly differ up to 18 weeks, demonstrating the highly immunogenic nature of VP1-based particulate structures. The carrier-specific antibody response was reproducibly detected in the meat juice after processing. More importantly, chimeric VP1 pentamers and VLPs carrying peptides of 12 and 14 amino acids in length, inserted into the BC2 loop, induced a strong and long-lasting humoral immune response against VP1 and the inserted foreign epitope. Remarkably, the epitope-specific antibody response was only moderately decreased when VP1 pentamers were used instead of VLPs. In conclusion, we identified polyomavirus VP1-based structures displaying surface-exposed immunodominant B cell epitopes as being an efficient carrier system for the induction of potent peptide-specific antibodies. The application of this approach in vaccine marker technology in livestock holding and the meat production chain is discussed. [source] DE-310, a novel macromolecular carrier system for the camptothecin analog DX-8951f: Potent antitumor activities in various murine tumor modelsCANCER SCIENCE, Issue 2 2004Eiji Kumazawa DE-310 is a novel macromolecular conjugate composed of DX-8951f, a camptothecin analog, and a carboxymethyldextran polyalcohol carrier, which are covalently linked via a peptidyl spacer. In a murine Meth A (fibrosarcoma) solid tumor model, once daily×5 treatments (qd×5) with DX-8951f at the maximum tolerated dose (MTD) were required to shrink the tumor, and DX-8951f (qd×5) at 1/4 MTD was required to inhibit tumor growth. A single treatment (qd×1) with DE-310 at the MTD or 1/4 MTD shrank the tumor, with no body weight loss occurring at 1/4 MTD. Even at 1/16 MTD, DE-310 inhibited tumor growth. In a long-term assay, Meth A solid tumors disappeared in mice treated with DE-310 (qd×1) at the MTD and 1/2 MTD, and all 6 mice remained tumor-free on the 60th day after administration. Repeated injection (4 times) on schedules of every 3 days, 7 days or 14 days demonstrated that multiple treatment with DE-310 produced greater tumor growth delay than a single treatment with DE-310. Against 5 human tumor (colon and lung cancer) xenografts in mice, DE-310 (qd×1) was as effective as DX-8951f administered once every 4 days, 4 times. The life-prolonging activity of DE-310 was assessed in lung (3LL, Lewis lung carcinoma) and liver (M5076, histiocytoma) metastasis models. Against 3LL, DE-310 (qdx1) at the MTD to 1/3 MTD significantly prolonged survival, with an increase in life span (ILS) of 4.8- to 1.6-fold, respectively, over that in untreated control mice. Also, DE-310 (qd×1) significantly prolonged survival in the liver metastasis model of M5076. These results demonstrate that DE-310 is a promising agent for the treatment of cancer. [source] Delivery of Nucleic Acids via Disulfide-Based Carrier SystemsADVANCED MATERIALS, Issue 32-33 2009Sonja Bauhuber Abstract Nucleic acids are not only expected to assume a pivotal position as "drugs" in the treatment of genetic and acquired diseases, but could also act as molecular cues to control the microenvironment during tissue regeneration. Despite this promise, the efficient delivery of nucleic acids to their side of action is still the major hurdle. One among many prerequisites for a successful carrier system for nucleic acids is high stability in the extracellular environment, accompanied by an efficient release of the cargo in the intracellular compartment. A promising strategy to create such an interactive delivery system is to exploit the redox gradient between the extra- and intracellular compartments. In this review, emphasis is placed on the biological rationale for the synthesis of redox sensitive, disulfide-based carrier systems, as well as the extra- and intracellular processing of macromolecules containing disulfide bonds. Moreover, the basic synthetic approaches for introducing disulfide bonds into carrier molecules, together with examples that demonstrate the benefit of disulfides at the individual stages of nucleic acid delivery, will be presented. [source] Precision Polymers: Monodisperse, Monomer-Sequence-Defined Segments to Target Future Demands of Polymers in MedicineADVANCED MATERIALS, Issue 32-33 2009L. Hartmann Abstract The established technology platforms of solid-phase-supported oligopeptide and oligonucleotide synthesis can be expanded to access fully synthetic macromolecules, preserving both the monodisperse character and the defined monomer sequence. Precision polymers are sequentially assembled from a library of functional building blocks, enabling one to program interaction capabilities or generate functions by sequence-specific positioning of functionalities. Examples are provided, showing that these monodisperse macromolecules can be conjugated to oligonucleotides, oligopeptides, or poly(ethylene glycol)s. The resulting model systems can contribute to the understanding of complex biomedical-related processes. Due to the absence of chemical and molecular-weight distributions in these multifunctional segments, exact correlation of the monomer sequence and (bio)properties is attainable. This is demonstrated by the design of carrier systems that exhibit fine-tuned interactions with plasmid DNA, actively controlling important steps in DNA delivery and transfection, such as polyplex formation, DNA compression, and release of the cargo. [source] Novel cosmetic delivery systems: an application updateINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2008V. B. Patravale Synopsis World consumers are nowadays more focused on their health and appearance. This trend is creating heightened demand for products formulated with natural and nutraceutical ingredients. Functional ingredients and innovative delivery systems are driving the new product development in the field of cosmetics. A significant number of innovative formulations are now being used in personal care with real consumer-perceivable benefits and optimized sensory attributes, resulting in an economic uplift of cosmetic industry. In fact, the U.S. market alone for novel cosmetic delivery systems has been projected to be more than $41 billion for the year 2007. Novel cosmetic delivery systems reviewed here possess enormous potential as next-generation smarter carrier systems. [source] Technological strategies to improve photostability of a sunscreen agentINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2006P. Perugini Due to the reduction of the ozone layer, there is an increasing need of effective UV protection systems with minimized side-effects. Trans-2-ethylhexyl- p -methoxycinnamate (trans -EHMC) represents one of the most widely used sunscreen compound. Several studies demonstrated that trans -EHMC is unstable following UV irradiation both in solution and in emulsion formulations. Moreover, various reports of photocontact sensitization induced by trans -EHMC have appeared in the literature. Consequently, in order to ensure adequate efficacy and safety for this sunscreen agent, there is a need for new carrier systems to enhance trans -EHMC photostability. In the present study the photostability of the filter in different formulation types (emulsion,gel, gel and emulsion) with various ingredients is evaluated. In addition, nanoparticles based on poly- D,L -lactide-co-glycolide (PLGA) as carrier for trans -EHMC are investigated. The influence of nanoparticle matrix on the photochemical stability of the sunscreen agent is also presented. The results obtained demonstrated that PLGA nanoparticles are effective in reducing the light-induced degradation of the sunscreen agent. Moreover, the choice of formulation type and the excipients used play an important role in order to obtain a stable cosmetic product containing trans -EHMC. [source] Dermal delivery of desmopressin acetate using colloidal carrier systemsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2005Melkamu Getie Recently, the transdermal route has received attention as a promising means to enhance the delivery of drug molecules, particularly peptides, across the skin. In this work, the skin penetration profiles of desmopressin acetate from a colloidal system (water-in-oil microemulsion) and an amphiphilic cream, a standard formulation, were determined using Franz diffusion cells and compared. In the case of the microemulsion, the total percentages of dose obtained from different skin layers (stratum corneum to subcutaneous tissue) were 3.30 ± 0.67, 7.37 ± 2.43 and 15.54 ± 2.72 at 30, 100 and 300 min, respectively. Similarly, 5.19 ± 0.96, 8.04 ± 0.97 and 14.4 ± 5.15% of the dose applied was extracted from the skin treated with the cream. About 6% of the applied dose reached the acceptor compartment from the microemulsion instead of 2% from the cream within 300 min. The concentration of drug that penetrated into the upper layers of the skin was higher from the cream than from the microemulsion at all time intervals. On the other hand, a higher amount of drug was found in the deeper skin layers and in the acceptor compartment from the microemulsion. [source] Tailored Albumin-based Copolymers for Receptor-Mediated Delivery of Perylenediimide Guest MoleculesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 17 2010Klaus Eisele Abstract The synthesis of a novel and multifunctional copolymer based on a human serum albumin backbone bearing several folic acid as well as PEO groups was presented. In solution, this side-chain copolymer adopts a globular architecture and about five molecules of the water-insoluble chromophore PDI were successfully incorporated into these micelles for receptor-mediated cell uptake investigations. A significant uptake of these bioconjugates via receptor-mediated endocytosis was detected for cells expressing folic acid receptors in the cell membrane. These novel albumin-based copolymers could serve as efficient and biocompatible carrier systems facilitating the directed delivery of lipophilic drug molecules into cancer cells and they allow investigating vesicle formation and trafficking even at the single molecule level. [source] Surface properties of poly(lactic/glycolic acid),pluronic® blend filmsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11-12 2003É. Kiss Abstract Poly(dl -lactide) (PLA) and two of its random copolymers with glycolic acid, poly(dl -lactide- co -glycolide) (PLGA) with 75/25 and 50/50 component ratios of lactide/glycolide were blended with poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEO,PPO,PEO) triblock non-ionic surfactants, known by the Pluronic® trade names of PE6100, PE6400 and PE6800. The surface chemical compositions of the blended films were identified by X-ray photoelectron spectroscopy (XPS). Based on the component of the carbon signal assigned to the ether carbon of the Pluronic® molecule, quantification of the surface accumulation of the Pluronic® additive, compared to its bulk concentration, was performed. The data demonstrated that PEO-containing surfaces were prepared by the blending process. A significant surface hydrophilization, characterized by wettability measurements, was obtained by applying the Pluronics® at a concentration of 1.0,9.1,wt% in the blends. The composition of the surface layer and, in accordance with this, the wettability of the film were found to be dependent on the type of Pluronic® and on the composition of the unmodified polymer. Protein adsorption on the polymer films was measured by the FT-IR ATR spectroscopic technique. The adsorbed amount of bovine serum albumin onto PLA was highly reduced when the polymer was blended with a Pluronic®. The increased hydrophilicity and the reduced protein adsorption properties of the PLA and PLGA obtained by blending with PEO compounds might contribute to their applications as drug carrier systems with great potential. Copyright © 2003 John Wiley & Sons, Ltd. [source] Biodegradable comb polyesters containing polyelectrolyte backbones facilitate the preparation of nanoparticles with defined surface structure and bioadhesive properties,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10-12 2002A. Breitenbach Abstract A major challenge in oral peptide and protein delivery remains the search for suitable carrier systems. Therefore, a new concept was investigated combining a modified three-dimensional architecture, increased hydrophilicity of poly(lactic- co -glycolic acid) (PLGA) and charged groups in a single polymer. Biodegradable comb PLGA were synthesized by grafting short PLGA chains onto different poly(vinyl alcohol) (PVA) based backbone polyols, poly(2-sulfobutyl-vinyl alcohol) and poly(diethylaminoethyl-vinyl alcohol). The polyelectrolyte backbones were obtained by etherification of PVA with charge-containing pendent groups. The comb polymer structure could be confirmed by nuclear magnetic resonance, infrared spectroscopy, differential scanning calorimetry, elemental analysis and measurement of intrinsic viscosity. Nanoparticles (NP), as potential mucosal carriers systems, were prepared by controlled precipitation and investigated as a function of polymer composition. The amphiphilic character and the three-dimensional architecture of the novel polyesters allowed the preparation of small nanoparticles even without the use of surfactants. Surface NMR, surface charge and hydrophobicity determination indicate a core,corona-like NP structure, especially in the case of negatively charged polyesters. A structural model is proposed for the NP with an inner polyester core and an outer charged-groups-containing surface, depending on polymer composition and backbone charge density. The higher the polymer backbone charge density, the more pronounced its influence on the nanoparticle surface properties. The possibility of preparing NP without the use of a surfactant, as well as of designing the NP surface characteristics by polymer backbone charge density and polymer hydrophilic,hydrophobic balance, will be a major advantage in protein adsorption, bioadhesion and organ distribution. This makes these biodegradable polymers promising candidates for colloidal protein and peptide delivery. Copyright © 2003 John Wiley & Sons, Ltd. [source] Pharmaceutical and Biomedical Differences between Micellar Doxorubicin (NK911) and Liposomal Doxorubicin (Doxil)CANCER SCIENCE, Issue 10 2002Yoshihisa Tsukioka The stability and biological behavior of an in vitro system of doxorubicin (DXR) entrapped in NK911, polymer micelles, was examined and compared with those of DXR entrapped in Doxil, polyethylene-glycol-conjugated liposomes. The fluorescence of DXR inside micelles or liposomes in an aqueous solution is known to be strongly quenched by the outer shells of the micellar or liposomal formation. Thus, by measuring the fluorescence intensity of DXR released from NK911 or Doxil, we could determine the stability of the micellar or liposomal DXR formation. Furthermore, NK911 was found to be less stable than Doxil in saline solution. In drug distribution experiments using an in vitro solid tumor model, when spheroids formed from two human colonic cancer lines, HT-29 and WiDr, and a human stomach cancer line, MKN28, were exposed to NK911, DXR was distributed throughout the spheroids, including their center. On the other hand, when the spheroids were exposed to Doxil, DXR was distributed only to the surface of the spheroids. It has been suggested that Doxil can deliver DXR to a solid tumor more efficiently than NK911 via the EPR (enhanced permeability and retention) effect, because Doxil may be more stable in plasma than NK911. On the other hand, DXR packed in NK911 may be distributed by diffusion to cancer cells distant from the tumor vessel, because NK911 can leak out of the tumor vessel and may be able to release free DXR more easily than Doxil. It has been suggested that drug carrier systems such as liposomes and micelles should be selected appropriately bearing in mind the characteristics of the tumor vasculature and the tumor interstitium. [source] Ion and pH Sensing with Colloidal Nanoparticles: Influence of Surface Charge on Sensing and Colloidal PropertiesCHEMPHYSCHEM, Issue 3 2010Feng Zhang Dr. Abstract Ion sensors based on colloidal nanoparticles (NPs), either as actively ion-sensing NPs or as nanoscale carrier systems for organic ion-sensing fluorescent chelators typically require a charged surface in order to be colloidally stable. We demonstrate that this surface charge significantly impacts the ion binding and affects the read-out. Sensor read-out should be thus not determined by the bulk ion concentration, but by the local ion concentration in the nano-environment of the NP surface. We present a conclusive model corroborated by experimental data that reproduces the strong distance-dependence of the effect. The experimental data are based on the capability of tuning the distance of a pH-sensitive fluorophore to the surface of NPs in the nanometer (nm) range. This in turn allows for modification of the effective acid dissociation constant value (its logarithmic form, pKa) of analyte-sensitive fluorophores by tuning their distance to the underlying colloidal NPs. [source] Biodegradable comb polyesters containing polyelectrolyte backbones facilitate the preparation of nanoparticles with defined surface structure and bioadhesive properties,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10-12 2002A. Breitenbach Abstract A major challenge in oral peptide and protein delivery remains the search for suitable carrier systems. Therefore, a new concept was investigated combining a modified three-dimensional architecture, increased hydrophilicity of poly(lactic- co -glycolic acid) (PLGA) and charged groups in a single polymer. Biodegradable comb PLGA were synthesized by grafting short PLGA chains onto different poly(vinyl alcohol) (PVA) based backbone polyols, poly(2-sulfobutyl-vinyl alcohol) and poly(diethylaminoethyl-vinyl alcohol). The polyelectrolyte backbones were obtained by etherification of PVA with charge-containing pendent groups. The comb polymer structure could be confirmed by nuclear magnetic resonance, infrared spectroscopy, differential scanning calorimetry, elemental analysis and measurement of intrinsic viscosity. Nanoparticles (NP), as potential mucosal carriers systems, were prepared by controlled precipitation and investigated as a function of polymer composition. The amphiphilic character and the three-dimensional architecture of the novel polyesters allowed the preparation of small nanoparticles even without the use of surfactants. Surface NMR, surface charge and hydrophobicity determination indicate a core,corona-like NP structure, especially in the case of negatively charged polyesters. A structural model is proposed for the NP with an inner polyester core and an outer charged-groups-containing surface, depending on polymer composition and backbone charge density. The higher the polymer backbone charge density, the more pronounced its influence on the nanoparticle surface properties. The possibility of preparing NP without the use of a surfactant, as well as of designing the NP surface characteristics by polymer backbone charge density and polymer hydrophilic,hydrophobic balance, will be a major advantage in protein adsorption, bioadhesion and organ distribution. This makes these biodegradable polymers promising candidates for colloidal protein and peptide delivery. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||