Browsing by Subject "Dissolution"

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  • Khakalo, Alexey; Tanaka, Atsushi; Korpela, Antti; Hauru, Lauri K. J.; Orelma, Hannes (2019)
    Synthetic structural materials of high mechanical performance are typically either of large weight (for example, steels, and alloys) or involve complex manufacturing processes and thus have high cost or cause adverse environmental impact (for example, polymer-based and biomimetic composites). In this perspective, low-cost, abundant and nature-based materials, such as wood, represent particular interest provided they fulfill the requirements for advanced engineering structures and applications, especially when manufactured totally additive-free. Here, we report on a novel all-wood material concept based on delignification, partial surface dissolution using ionic liquid (IL) followed by densification resulting in a high-performance material. A delignification process using sodium chlorite in acetate buffer solution was applied to controllably delignify the entire bulk wooden material while retaining the highly beneficial structural directionality of wood. In a subsequent step, obtained delignified porous wood template was infiltrated with an IL 1-ethyl-3-methylimidazolium acetate, [EMIM]OAc and heat activated at 95 degrees C to partially dissolve the fiber surface. Afterward, treated wood was washed with water to remove IL and hot-pressed to gain a very compact cellulosic material with fused fibers while retaining unidirectional fiber orientation. The obtained cellulose materials were structurally, chemically, and mechanically characterized revealing superior tensile properties compared to native wood. Furthermore, suggested approach allows almost 8-fold tensile strength improvement in the direction perpendicular to fiber orientation, which is otherwise very challenging to achieve.
  • Pessi, Jenni; Svanbäck, Sami; Lassila, Ilkka; Haeggstrom, Edward; Yliruusi, Jouko (2017)
    We introduce a system with a lyophilic matrix to aid dissolution studies of powders and particulate systems. This lyophilic matrix method (LM method) is based on the ability to discriminate between non-dissolved particles and the dissolved species. In the LM method the test substance is embedded in a thin lyophilic core-shell matrix. This permits rapid contact with the dissolution medium while minimizing dispersion of non-dissolved particles without presenting a substantial diffusion barrier. The method produces realistic dissolution and release results for particulate systems, especially those featuring nanoscale particles. By minimizing method-induced effects on the dissolution profile of nanopowders, the LM method overcomes shortcomings associated with current dissolution tests. (C) 2017 Elsevier B.V. All rights reserved.
  • Ojarinta, Rami; Saarinen, Jukka; Strachan, Clare J.; Korhonen, Ossi; Laitinen, Riikka (2018)
    Co-amorphous mixtures have rarely been formulated as oral dosage forms, even though they have been shown to stabilize amorphous drugs in the solid state and enhance the dissolution properties of poorly soluble drugs. In the present study we formulated tablets consisting of either spray dried co-amorphous ibuprofen-arginine or indomethacin-arginine, mannitol or xylitol and polyvinylpyrrolidone K30 (PVP). Experimental design was used for the selection of tablet compositions, and the effect of tablet composition on tablet characteristics was modelled. Multimodal non-linear imaging, including coherent anti-Stokes Raman scattering (CARS) and sum frequency/second harmonic generation (SFG/SHG) microscopies, as well as scanning electron microscopy, X-ray diffractometry and Fourier-transform infrared spectroscopy were utilized to characterize the tablets. The tablets possessed sufficient strength, but modelling produced no clear evidence about the compaction characteristics of co-amorphous salts. However, co-amorphous drug-arginine mixtures resulted in enhanced dissolution behaviour, and the PVP in the tableting mixture stabilized the supersaturation. The co-amorphous mixtures were physically stable during compaction, but the excipient selection affected the long term stability of the ibuprofen-arginine mixture. CARS and SFG/SHG proved feasible techniques in imaging the component distribution on the tablet surfaces, but possibly due to the limited imaging area, recrystallization detected with xray diffraction was not detected.