Chitosan Aerogel Particles as Nasal Drug Delivery Systems

The nasal drug delivery route has distinct advantages, such as high bioavailability, a rapid therapeutic effect, non-invasiveness, and ease of administration. This article presents the results of a study of the processes for obtaining chitosan aerogel particles that are promising as nasal or inhalation drug delivery systems. Obtaining chitosan aerogel particles includes the following steps: the preparation of a chitosan solution, gelation, solvent replacement, and supercritical drying. Particles of chitosan gels were obtained by spraying and homogenization. The produced chitosan aerogel particles had specific surface areas of up to 254 m²/g, pore volumes of up to 1.53 cm³/g, and porosities of up to 99%. The aerodynamic diameters of the obtained chitosan aerogel particles were calculated, the values of which ranged from 13 to 59 µm. According to the calculation results, a CS1 sample was used as a matrix for obtaining the pharmaceutical composition "chitosan aerogel-clomipramine". X-ray diffraction (XRD) analysis of the pharmaceutical composition determined the presence of clomipramine, predominantly in an amorphous form. Analysis of the high-performance liquid chromatography (HPLC) data showed that the mass loading of clomipramine was 35%. Experiments in vivo demonstrated the effectiveness of the pharmaceutical composition "chitosan aerogel-clomipramine" as carrier matrices for the targeted delivery of clomipramine by the "Nose-to-brain" mechanism of nasal administration. The maximum concentration of clomipramine in the frontal cortex and hippocampus was reached 30 min after administration.

Czochralski growth of mixed cubic sesquioxide crystals in the ternary system Lu2O3–Sc2O3–Y2O3

The phase diagram of the ternary system Lu₂O₃–Sc₂O₃–Y₂O₃ is investigated and compositions with melting points below 2200°C are found. This allows for the first successful growth of the mixed cubic sesquioxide crystal (Er_0.07Sc_0.50Y_0.43)₂O₃ by the Czochralski method from an iridium crucible.

Cubic rare-earth sesquioxide crystals are strongly demanded host materials for high power lasers, but due to their high melting points investigations on their thermodynamics and the growth of large-size crystals of high optical quality remain a challenge. Detailed thermal investigations of the ternary system Lu₂O₃–Sc₂O₃–Y₂O₃ revealing a large range of compositions with melting temperatures below 2200°C and a minimum of 2053°C for the composition (Sc_0.45Y_0.55)₂O₃ are presented. These reduced temperatures enable for the first time the growth of high optical quality mixed sesquioxide crystals with disordered structure by the conventional Czochralski method from iridium crucibles. An (Er­_0.07Sc_0.50Y_0.43)₂O₃ crystal is successfully grown and characterized with respect to its crystallographic properties as well as its composition, thermal conductivity and optical absorption in the 1 µm range.