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      International Journal of Nanomedicine (submit here)

      This international, peer-reviewed Open Access journal by Dove Medical Press focuses on the application of nanotechnology in diagnostics, therapeutics, and drug delivery systems throughout the biomedical field. Sign up for email alerts here.

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      Novel PEG-graft-PLA nanoparticles with the potential for encapsulation and controlled release of hydrophobic and hydrophilic medications in aqueous medium

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          Abstract

          This study concerns the encapsulation and controlled release of both hydrophobic and hydrophilic medications with one polymer, which are delivered together as a combined therapy to treat diseased tissue. To test our hypothesis that the novel PEG-graft-PLA (PEG, polyethylene glycol; PLA, polylactic acid) can deliver both the hydrophobic and hydrophilic medications on account of its amphiphility, charge, and graft structure, PEG-graft-PLA (molecular weight of PEG = 1900) with very low critical micelle concentration was synthesized. One hydrophilic (insulin) and one hydrophobic (naproxen) model medication were loaded in separately during its self-assembly in aqueous solution. The resulting nanoparticles (NPs) were narrowly distributed and spherical, with average particle size around 200 nm, zeta potential >−10 mV, and encapsulation efficiency >50%. The NPs realized controlled release of insulin and naproxen for over 24 and 160 hours, respectively. Specifically, the bioactivity of the insulin released from the NPs was maintained. Owing to encapsulation, both for hydrophobic and hydrophilic medicines, and NPs obtained with similar size and zeta potential, as well as maintenance of bioactivity of loaded protein, we expect the applications of PEG-graft-PLA NPs in combination therapy.

          Most cited references38

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          Protein drug stability: a formulation challenge.

          The increasing use of recombinantly expressed therapeutic proteins in the pharmaceutical industry has highlighted issues such as their stability during long-term storage and means of efficacious delivery that avoid adverse immunogenic side effects. Controlled chemical modifications, such as substitutions, acylation and PEGylation, have fulfilled some but not all of their promises, while hydrogels and lipid-based formulations could well be developed into generic delivery systems. Strategies to curb the aggregation and misfolding of proteins during storage are likely to benefit from the recent surge of interest in protein fibrillation. This might in turn lead to generally accepted guidelines and tests to avoid unforeseen adverse effects in drug delivery.
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            'Stealth' corona-core nanoparticles surface modified by polyethylene glycol (PEG): influences of the corona (PEG chain length and surface density) and of the core composition on phagocytic uptake and plasma protein adsorption.

            Nanoparticles possessing poly(ethylene glycol) (PEG) chains on their surface have been described as blood persistent drug delivery system with potential applications for intravenous drug administration. Considering the importance of protein interactions with injected colloidal dug carriers with regard to their in vivo fate, we analysed plasma protein adsorption onto biodegradable PEG-coated poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) and poly(varepsilon-caprolactone) (PCL) nanoparticles employing two-dimensional gel electrophoresis (2-D PAGE). A series of corona/core nanoparticles of sizes 160-270 nm were prepared from diblock PEG-PLA, PEG-PLGA and PEG-PCL and from PEG-PLA:PLA blends. The PEG Mw was varied from 2000-20000 g/mole and the particles were prepared using different PEG contents. It was thus possible to study the influence of the PEG corona thickness and density, as well as the influence of the nature of the core (PLA, PLGA or PCL), on the competitive plasma protein adsorption, zeta potential and particle uptake by polymorphonuclear (PMN) cells. 2-D PAGE studies showed that plasma protein adsorption on PEG-coated PLA nanospheres strongly depends on the PEG molecular weight (Mw) (i.e. PEG chain length at the particle surface) as well as on the PEG content in the particles (i.e. PEG chain density at the surface of the particles). Whatever the thickness or the density of the corona, the qualitative composition of the plasma protein adsorption patterns was very similar, showing that adsorption was governed by interaction with a PLA surface protected more or less by PEG chains. The main spots on the gels were albumin, fibrinogen, IgG, Ig light chains, and the apolipoproteins apoA-I and apoE. For particles made of PEG-PLA45K with different PEG Mw, a maximal reduction in protein adsorption was found for a PEG Mw of 5000 g/mole. For nanospheres differing in their PEG content from 0.5 to 20 wt %, a PEG content between 2 and 5 wt % was determined as a threshold value for optimal protein resistance. When increasing the PEG content in the nanoparticles above 5 wt % no further reduction in protein adsorption was achieved. Phagocytosis by PMN studied using chemiluminescence and zeta potential data agreed well with these findings: the same PEG surface density threshold was found to ensure simultaneously efficient steric stabilization and to avoid the uptake by PMN cells. Supposing all the PEG chains migrate to the surface, this would correspond to a distance of about 1.5 nm between two terminally attached PEG chains in the covering 'brush'. Particles from PEG5K-PLA45K, PEG5K-PLGA45K and PEG5K-PCL45K copolymers enabled to study the influence of the core on plasma protein adsorption, all other parameters (corona thickness and density) being kept constant. Adsorption patterns were in good qualitative agreement with each other. Only a few protein species were exclusively present just on one type of nanoparticle. However, the extent of proteins adsorbed differed in a large extent from one particle to another. In vivo studies could help elucidating the role of the type and amount of proteins adsorbed on the fate of the nanoparticles after intraveinous administration, as a function of the nature of their core. These results could be useful in the design of long circulating intravenously injectable biodegradable drug carriers endowed with protein resistant properties and low phagocytic uptake.
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              Highly active antiretroviral treatment as prevention of HIV transmission: review of scientific evidence and update.

              An estimated 33 million people are living with HIV and universal access remains a dream for millions of people. By the end of year 2008, four million people were on treatment; however, over five million needed treatment, and in 2007, there were 2.7 million new infections. Without significant improvement in prevention, we are unlikely to meet universal access targets including the growing demand for highly active antiretroviral treatment (HAART). This review examines HAART as a potential tool for preventing HIV transmission. We discuss recent scientific evidence regarding the treatment and prevention gap, importance viral load and HIV transmission, HAART and HIV transmission, when to start, HIV counseling and testing, modeling results and next steps. HAART has considerable treatment and prevention benefits and it needs to be considered as a key element of combination prevention. To explore HAART as an effective prevention strategy, we recommend further evaluation of human rights and ethical considerations, clarification of research priorities and exploration of feasibility and acceptability issues.
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                Author and article information

                Journal
                Int J Nanomedicine
                International Journal of Nanomedicine
                Dove Medical Press
                1176-9114
                1178-2013
                2011
                2011
                07 July 2011
                : 6
                : 1443-1451
                Affiliations
                [1 ]Bioengineering College, Chongqing University, Chongqing, People’s Republic of China
                [2 ]Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing, People’s Republic of China
                Author notes
                Correspondence: Jun Pan, Gurinder K Singh, Bioengineering College, Chongqing, University, Chongqing, 400044, People’s, Republic of China, Tel +86 23 65102507, Fax +86 23 65102507, Email panj@ 123456cqu.edu.cn , singhg@ 123456cqu.edu.cn

                The first two authors contributed equally to this work

                Article
                ijn-6-1443
                10.2147/IJN.S19765
                3141871
                21796246
                40e242f8-9d90-49bf-883b-a7b151a0a813
                © 2011 Wang et al, publisher and licensee Dove Medical Press Ltd.

                This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited.

                History
                Categories
                Original Research

                Molecular medicine
                naproxen,insulin,combination therapy,nps,controlled release
                Molecular medicine
                naproxen, insulin, combination therapy, nps, controlled release

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