Browsing by Subject "NANOPARTICLE"

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  • Bulatov, Evgeny; Lahtinen, Elmeri; Kivijärvi, Lauri; Hey-Hawkins, Evamarie; Haukka, Matti (2020)
    Selective laser sintering (SLS) 3d printing was utilized to manufacture a solid catalyst for Suzuki-Miyaura cross-coupling reactions from polypropylene as a base material and palladium nanoparticles on silica (SilicaCat Pd(0)R815-100 by SiliCycle) as the catalytically active additive. The 3d printed catalyst showed similar activity to that of the pristine powdery commercial catalyst, but with improved practical recoverability and reduced leaching of palladium into solution. Recycling of the printed catalyst led to increase of the induction period of the reactions, attributed to the pseudo-homogeneous catalysis. The reaction is initiated by oxidative addition of aryl iodide to palladium nanoparticles, resulting in formation of soluble molecular species, which then act as the homogeneous catalyst. SLS 3d printing improves handling, overall practicality and recyclability of the catalyst without altering the chemical behaviour of the active component.
  • Yu, Qing; England, Richard M.; Gunnarsson, Anders; Luxenhofer, Robert; Treacher, Kevin; Ashford, Marianne B. (2022)
    Polymeric micelles have been extensively used as nanocarriers for the delivery of chemotherapeutic agents, aiming to improve their efficacy in cancer treatment. However, the poor loading capacity, premature drug release, non-uniformity, and reproducibility still remain the major challenges. To create a stable polymeric micelle with high drug loading, a telodendrimer micelle was developed as a nanocarrier for fulvestrant, as an example of a drug that has extremely poor water solubility (sub-nanomolar range). Telodendrimers were prepared by the synthesis of hydrophilic linear poly(sarcosine) and growing a lysine dendron from the chain terminal amine by divergent synthesis. At the periphery of the dendritic block, either 4, 8, or 16 fulvestrant molecules were conjugated to the lysine dendron creating a hydrophobic block. Having drug molecules as a part of the carrier not only reduces the usage of the inert carrier materials but also prevents the drugs from leakage and premature release by diffusion. The self-assembled telodendrimer micelles demonstrated good colloidal stability (cmc < 2 mu M) in buffer and were uniform in size. In addition, these telodendrimer micelles could solubilize additional fulvestrant yielding an excellent overall drug loading capacity of up to 77 wt % total drug load (summation of conjugated and encapsulated). Importantly, the size of the micelles could be tuned between 25 and 150 nm by controlling (i) the ratio between hydrophilic and hydrophobic blocks and (ii) the amount of encapsulated fulvestrant. The versatility of these telodendrimer-based micelle systems to both conjugated and encapsulated drugs with high efficiency and stability, in addition to possessing other tuneable properties, makes it a promising drug delivery system for a range of active pharmaceutical ingredients and therapeutic targets.
  • Kickova, Eva; Salmaso, Stefano; Mastrotto, Francesca; Caliceti, Paolo; Urtti, Arto (2021)
    Posterior segment eye diseases are mostly related to retinal pathologies that require pharmacological treatments by invasive intravitreal injections. Reduction of frequent intravitreal administrations may be accomplished with delivery systems that provide sustained drug release. Pullulan-dexamethasone conjugates were developed to achieve prolonged intravitreal drug release. Accordingly, dexamethasone was conjugated to similar to 67 kDa pullulan through hydrazone bond, which was previously found to be slowly cleavable in the vitreous. Dynamic light scattering and transmission electron microscopy showed that the pullulan-dexamethasone containing 1:20 drug/glucose unit molar ratio (10% w/w dexamethasone) self-assembled into nanoparticles of 461 +/- 30 nm and 402 +/- 66 nm, respectively. The particles were fairly stable over 6 weeks in physiological buffer at 4, 25 and 37 degrees C, while in homogenized vitreous at 37 degrees C, the colloidal assemblies underwent size increase over time. The drug was released slowly in the vitreous and rapidly at pH 5.0 mimicking lysosomal conditions: 50% of the drug was released in about 2 weeks in the vitreous, and in 2 days at pH 5.0. In vitro studies with retinal pigment epithelial cell line (ARPE-19) showed no toxicity of the conjugates in the cells. Flow cytometry and confocal microscopy showed cellular association of the nanoparticles and intracellular endosomal localization. Overall, pullulan conjugates showed interesting features that may enable their successful use in intravitreal drug delivery.