Encapsulation of Metronidazole in Biocompatible Macrocycles and Structural Characterization of Its Nano Spray-Dried Nanostructured Composite

Abstract

Due to the great potential of biocompatible cucurbit[7]uril (CB7) and 4-sulfonatocalix[4]arene (SCX4) macrocycles in drug delivery, the confinement of the pharmaceutically important metronidazole as an ionizable model drug has been systematically studied in these cavitands. Absorption and fluorescence spectroscopic measurements gave 1.9 × 105 M−1 and 1.0 × 104 M−1 as the association constants of the protonated metronidazole inclusion in CB7 and SCX4, whereas the unprotonated guests had values more than one order of magnitude lower, respectively. The preferential binding of the protonated metronidazole resulted in 1.91 pH unit pKa diminution upon encapsulation in CB7, but the complexation with SCX4 led to a pKa decrease of only 0.82 pH unit. The produced protonated metronidazole–SCX4 complex induced nanoparticle formation with protonated chitosan by supramolecular crosslinking of the polysaccharide chains. The properties of the aqueous nanoparticle solutions and the micron-sized solid composite produced therefrom by nano spray drying were unraveled. The results of the present work may find application in the rational design of tailor-made self-assembled drug carrier systems.

Increased Range of Catalytic Activities of Immobilized Compared to Colloidal Gold Nanoparticles

“…The previous MTZ solution was incubated in contact with or without (control) AuNPscit (0.5, 1.0, or 1.7 × 10 12 AuNPs) or with 5, 10, and 30iAuNPs at 20 ± 1 • C under visible light and stirring (150 rpm). After the reaction was completed (10 min), the absorbance was read at 320 nm (molar absorption coefficient ε MTZ = 8730 M −1 •cm −1 [53]). The reduction efficiency was calculated using Equation (11): Degradation efficiency (%) = (C 0 − C 1 )/C 0 × 100 (11) where C 0 is the concentration of the control at 10 min and C 1 is the concentration of the sample.…”

Unveiling the synergy: a combined experimental and theoretical study of β-cyclodextrin with melatonin

“…28 Nano Spray Dryer synthetic pathway provides high production rates and low operating costs: for these reasons, it is considered a commercially applicable drying method in Drug Delivery Systems. 29 Current applications of Nano Spray Dryer concern encapsulation of organic molecules through a host-guest interaction [30][31][32] also in combination with a cyclodextrin forced to interact with essential oils 33 or levocetirizine. 34 Computational chemistry is a well-established and paradigmatic pillar in the study of drug delivery systems.…”