China
Africa
Explore chapters and articles related to this topic
Solid Lipid Nanoparticles for Anti-Tumor Drug Delivery
Published in Mansoor M. Amiji, Nanotechnology for Cancer Therapy, 2006
Ho Lun Wong, Yongqiang Li, Reina Bendayan, Mike Andrew Rauth, Xiao Yu Wu
Rather than avoiding the complexity caused by lipid polymorphism and crystallinity, some researchers attempted to exploit this phenomenon, and they turned it into a useful feature. For instance, the polymorphic conversion of lipid matrix from the meta-stable β′ form to the stable β form, as confirmed by form wide-angle x-ray scattering pattern, altered drug release rate,44 suggesting that by careful design, release rate of SLN can be modulated by controlling the polymorphic interconversion.
Loading, release profile and accelerated stability assessment of monoterpenes-loaded solid lipid nanoparticles (SLN)
Published in Pharmaceutical Development and Technology, 2020
Aleksandra Zielińska, Nuno R. Ferreira, Agnieszka Feliczak-Guzik, Izabela Nowak, Eliana B. Souto
Because of the possibility for the organization of alkane chains into different packing patterns: α (hexagonal – the most disordered), β´(orthorhombic) and β (triclinic – the most organized), lipids can occur in different polymorphic forms (Allais et al. 2003; Beck et al. 2011). Furthermore, the polymorphic structure may directly influence on the encapsulation efficiency and expulsion of the drug during storage (Beck et al. 2011). Therefore, it is necessary to detect the possible existence of the polymorphism before the introduction of SLN in the industry. In this work, X-ray diffraction (XRD) analysis was applied to determine the structure on the SLN dispersions, composed by the solid lipid, drug, surfactant and dispersion medium. Two XRD techniques, for which the main difference is the range of scattering angles 2θ (Westesen et al. 1993; Allais et al. 2003), have been applied, namely small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS), and wide angle X-ray scattering (WAXS) and neutron diffraction (ND). Both of methods detect electron (X-ray scattering) and nucleus (neutron scattering) density fluctuations, respectively, on a length scale d according to Bragg’s law: 2d sin θ = λ (Bunjes and Unruh 2007).
Impact of storage on the physico-chemical properties of microparticles comprising a hydrogenated vegetable oil matrix and different essential oil concentrations
Published in Journal of Microencapsulation, 2019
Pia Gottschalk, Benjamin Brodesser, Denis Poncelet, Henry Jaeger, Harald Rennhofer, Stephen Cole
X-ray powder diffraction scattering was performed with a Rigaku SMax3000 (Rigaku, Tokyo, Japan) with a Triton200 (Rigaku, Tokyo, Japan) multiple wire detector for the small angle X-ray scattering and a Fuji Image Plate (Fuji, Tokyo, Japan) for wide angle X-ray diffraction. The wide angle X-ray scattering images were recorded in one single shot of 1800 s exposure time in the range of 1–4.5 Å−1 (corresponding to 14–67 degree scattering angle) and the Fuji Image Plate was read out with a resolution of 0.0453 degrees scattering angle. The small angle X-ray scattering images were also recorded in one single shot but for 3600 s each in the range of 0.01–1 Å−1. A MM002+ micro focus X-ray tube with copper target (Cu-Kα, wavelength 0.154 nm) and integrated confocal max-flux small angle X-ray scattering optics (Rigaku) was operated with 45 kV and 0.88 mA. The system uses a 3-pinhole collimation to obtain a circular beam of about 210 µm diameter on the sample. For the sample preparation, a small amount of the microparticles was fixed between two plastic stripes. The signal from the plastic stripes alone was subtracted from the signals coming from the samples to eliminate the background signal.
Formation of essential oil containing microparticles comprising a hydrogenated vegetable oil matrix and characterisation thereof
Published in Journal of Microencapsulation, 2018
Pia Gottschalk, Benjamin Brodesser, Denis Poncelet, Henry Jaeger, Harald Rennhofer, Stephen Cole
X-ray diffraction powder scattering analysis was performed to investigate the crystalline structure of the microparticles and to clarify if the melting peak shifts between the unprocessed hydrogenated fat flakes and the spray-chilled particles consisting of pure hydrogenated fat are driven by polymorphic transformation. Another aim was to clarify if the characteristic melting profile of the microparticles containing essential oil and especially the reduction of the melting peak temperature with increasing essential oil concentration can be explained by polymorphic transformation. Furthermore, the wide angle X-ray scattering signal can be used to determine the crystallinity of a product. A widely applied approach is the construction of the background (Challa et al. 1962), indicating that a sustained, convex WAXS range is characteristic for an amorphous material. Regularly arranged peaks in the WAXS signal are a characteristic of the material having a crystalline structure. Figure 5(A) shows the small angle X-ray scattering (SAXS) signals gained for the unprocessed hydrogenated fat flakes and the microparticles without and with different concentrations of essential oil. The spray-chilling process itself did not have any influence on the crystalline structure of the hydrogenated fat. Both the unprocessed hydrogenated fat flakes and the microparticles without essential oil had a first scattering vector (q01) at 0.124 Å−1, a second vector (q02) at 0.25 Å−1 and a third vector (q03) at 0.36 Å−1, corresponding to the (001), (002) and (003) spectrum of a double chain-length structure (Takeuchi et al.2002). With the addition of essential oil q01 shifted to 0.14 Å−1, q02 to 0.28 Å−1 and q03 to 0.42 Å−1. The regular arrangement of several scattering vectors can be associated with the classic lamellar structure of triglycerides. Knowing q01 the thickness (d) of a lamellar structure can be calculated with d = 2*π/q01 (Lopes et al. 2015). For the products without essential oil, this yields in a lamellar thickness of 50.65 Å which corresponds to the α-polymorphic form of tristearin. The microparticles with essential oil exhibit a lamellar thickness of 44.86 Å, representing the β-form of the tristearin polymorphs (Lavigne et al. 1993). Varying the essential oil concentration did not influence the lamellar structure.