289
where K s is the stability constant of the complex, [CD] is the concentration of CD-drug complex, and D and D* stand for the diffusion coefficient of the free drug and CD-drug complex,
respectively.
2 Materials
The solutions are prepared with ultrapure deionized water with a
maximum resistivity of 18 MΩ cm, which was obtained by means
of a Milli-Q RG purification system (Millipore Co.). All reagents
are analytical grade. All buffer solutions are stored at 4 °C in the
dark and warmed at 25 °C before use. KCl solutions are stored at
room temperature. Solutions of drugs are freshly prepared before
the experimental work in solvents previously degassed by argon.
1. Quercetin,
β-cyclodextrin,
quercetin-2-hydroxypropyl-βcyclodextrin (quercetin-2HP-β-CD complex, prepared as
described in detail in [33] using a freeze-drying procedure).
2. 0.1 M KCl in water.
3. Britton-Robinson buffers (BRB) at different pH values
(pH 4.0–11.0) prepared using an acidic stock solution (sepa2.1 Reagents
Fig. 1 Geometry of the 2HP-β-CD-quercetin complex chemical structure and position of frontier orbitals of
quercetin calculated using DFT (Spartan’14)
Electrochemistry Investigation of Drugs Encapsulated in Cyclodextrins
where K s is the stability constant of the complex, [CD] is the concentration of CD-drug complex, and D and D* stand for the diffusion coefficient of the free drug and CD-drug complex,
respectively.
2 Materials
The solutions are prepared with ultrapure deionized water with a
maximum resistivity of 18 MΩ cm, which was obtained by means
of a Milli-Q RG purification system (Millipore Co.). All reagents
are analytical grade. All buffer solutions are stored at 4 °C in the
dark and warmed at 25 °C before use. KCl solutions are stored at
room temperature. Solutions of drugs are freshly prepared before
the experimental work in solvents previously degassed by argon.
1. Quercetin,
β-cyclodextrin,
quercetin-2-hydroxypropyl-βcyclodextrin (quercetin-2HP-β-CD complex, prepared as
described in detail in [33] using a freeze-drying procedure).
2. 0.1 M KCl in water.
3. Britton-Robinson buffers (BRB) at different pH values
(pH 4.0–11.0) prepared using an acidic stock solution (sepa2.1 Reagents
Fig. 1 Geometry of the 2HP-β-CD-quercetin complex chemical structure and position of frontier orbitals of
quercetin calculated using DFT (Spartan’14)
Electrochemistry Investigation of Drugs Encapsulated in Cyclodextrins