pH-sensitive polymer nanospheres for use as a potential drug delivery vehicle.
ABSTRACT We report the development and characterization of pH-sensitive poly(2-tetrahydropyranyl methacrylate) [poly(THPMA)] nanospheres and demonstrate their feasibility as an effective drug delivery vehicle. Poly(THPMA) nanospheres were prepared using either the double emulsion or single emulsion method for the encapsulation of, respectively, water soluble (rhodamine B) or organic soluble (paclitaxel) payloads. The resulting nanospheres showed pH-dependent dissolution behavior, resulting in significant morphologic changes and loss of nanoparticle mass under mild acidic conditions (pH 5.1) with a half-life of 3.3 days, as compared to physiologic condition (pH 7.4) with a half-life of 6.2 days. The in vitro drug release profile of the paclitaxel-loaded poly(THPMA) nanospheres revealed that the rate of drug release in pH 5.1 acetate buffer was relatively faster than that in pH 7.4 HEPES buffer. Furthermore, poly(THPMA) nanospheres showed lower cytotoxicity and higher cellular uptake as compared to the FDA-approved PLGA-based nanospheres currently in clinical practice.
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ABSTRACT: Mg–Al layered double hydroxide nanopowders were synthesised by a facile coprecipitation technique at different pH conditions. LDH nanoparticles of higher aspect ratio with an average particle size of 26nm were obtained at pH 9 whereas a pH of 11.3 resulted in LDH nanoparticles of average size 50nm with lower aspect ratio and narrower size distribution. LDH–MTX organo–inorganic nanohybrid was produced with an average particle size of 53nm after intercalation of MTX into the interlayer space of LDH, as evident from the shift of (003) peak in X-ray diffraction. This was corroborated by the transmission electron micrograph, which showed an increase in average interlayer spacing from 8.00Å in pristine LDH to 21.4Å in LDH–MTX nanohybrid. Thermogravimetric analyses showed ∼33.2wt% MTX loading in the LDH structure. The MTX release profile from Mg–Al LDH–MTX nanohybrid in phosphate buffer saline at pH 7.4 follows Ritger–Peppas kinetics model which demonstrates that the release kinetics is diffusion controlled. An attempt has been made to explain the above observations based on the effect of electrical double layer repulsions on the growth of LDH nuclei, primarily considering significance of the particle morphology in drug delivery application.Ceramics International 03/2012; · 2.09 Impact Factor
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ABSTRACT: The possibility to control the fate of the cells responsible of secondary mechanisms following spinal cord injury (SCI) is one of the most relevant challenges to reduce the post traumatic degeneration of the spinal cord. In particular, microglia/macrophages associated inflammation appears to be a self-propelling mechanism which leads to progressive neurodegeneration and development of persisting pain state. In this study we analyzed the interactions between poly(methyl methacrylate) nanoparticles (PMMA-NPs) and microglia/macrophages in vitro and in vivo, characterizing the features that influence their internalization and ability to deliver drugs. The uptake mechanisms of PMMA-NPs were in-depth investigated, together with their possible toxic effects on microglia/macrophages. In addition, the possibility to deliver a mimetic drug within microglia/macrophages was characterized in vitro and in vivo. Drug-loaded polymeric NPs resulted to be a promising tool for the selective administration of pharmacological compounds in activated microglia/macrophages and thus potentially able to counteract relevant secondary inflammatory events in SCI.Journal of Controlled Release 11/2013; · 7.63 Impact Factor
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ABSTRACT: New type of hydrogel nanoparticles (HNp) based on chitosan are synthesized by the free radical graft-copolymerization reaction of peroxide containing chitosan derivative and 1-vinyl-2-pyrrolidone (VP) in the inverse miniemulsion droplets. Free radicals are formed upon thermal decomposition of the peroxide groups that are attached to the chitosan chain. After introduction of the cross-linker N,N-methylenebisacrylamide, more densely cross-linked HNp with a lower pH-dependant swelling rate are produced. The release behavior is investigated by fluorescence measurements using HNp loaded with either anionic sulforhodamine 101 or cationic rhodamine 123 fluorescent dye. The obtained results revealed that the crucial points in the release kinetic are the nature of used “payload” molecules and their interaction with the hydrogel matrix. Synthesized HNp are of potential interest for diverse biomedical applications including controlled drug release and diagnostic.Macromolecular Bioscience 04/2014; · 3.65 Impact Factor