Comparison of Micro‐ and Mesoporous Inorganic Materials in the Uptake and Release of the Drug Model Fluorescein and Its Analogues

Abstract

The uptake of the three species of the drug model fluorescein (fluorescein sodium salt (FNa), fluorescein free acid (F), and fluorescein diacetate (FDA)) by zeolite NaX and the mesoporous zeotype MCM-41 was investigated as well as their release rates into solutions at pH 7 and pH 4.5. UV/Vis analysis was carried out at a wavelength of 490 nm. Uptakes of the sodium salt of 9 % for zeolite X and 14 % for MCM suggest little penetration of the pores. The use of ethanol as the loading solvent for F resulted in little uptake for both zeolitic materials due to the successful competition of the ethanol for binding sites. Use of acetone (weaker proton acceptor) as loading solvent significantly improved the uptake of F to 17 % and 12 % for zeolite X and MCM, respectively, whilst the uptake of FDA in acetone increased still further to 22 % and 17 % for zeolite X and MCM, respectively. Generally there was a large initial release of the fluorescein analogues from the surface of the zeolites with very little further increase over time. The prescence of an esterase enzyme in the release medium of FDA tripled the release from MCM to 15 % but left the release from zeolite X unaffected at 6 %. The results obtained show that uptake of fluorescein and its analogues is dependent on the loading solvent used, the amount released is influenced by not only the solvent but the pH and the presence of enzymes in the release medium.

Hybrid Organic–Inorganic Silica Gel Carriers with Controlled Drug‐Delivery Properties

“…The mobile phase consisted of 70 % solution (v/v) of acetonitrile in acidified water; the effluent was monitorated at 270 nm and the injection volume was 20 mL. The effective concentration of ibuprofen in solution was calculated on the basis of Equation (1), [11] in which c eff is the corrected concentration at time t, c app is the apparent concentration at time t, v is the volume of sample taken and V is the total volume of dissolution medium.…”

“…Several research groups have investigated both drug storage and delivery properties of ordered mesoporous silica [6][7][8][9][10] and of sol-gel silica materials. [11][12][13] A major advantage in the use of a sol-gel is that the matrix can be generated in the presence of the drug molecule in a one-step process; moreover, the physicochemical features of silica could be suitably modulated by the control and the opportune variation of the parameter process (composition of precursor mixture, catalysts, pH, ageing). ReKeywords: drug delivery · ibuprofen · organic-inorganic hybrid composites · silica materials · sol-gel processes Abstract: Pure and modified silica materials were synthesised by a sol-gel process and used as carrier for the controlled release of ibuprofen, selected as model drug.…”

Submicron Particles of SBA-15 Modified with MgO as Carriers for Controlled Drug Delivery

“…Calculation of the corrected concentration of replaced ibuprofen is based on the following equation: C torr ϭC t ϩv(C 0 ϩC 1 ···ϩC tϪ1 )/V, where C torr is the corrected concentration at time t, C t is the apparent concentration at time t, v is the volume of sample taken and V is the total volume of the dissolution medium in vessel. 23) Characterization All solid samples were characterized by X-Ray Diffraction (XRD), Scanning Electronic Microscopy (SEM), Fourier Transform Infra Red (FTIR) spectroscopy, The transmission electron microscopic (TEM), and N 2 adsorption. X-ray diffraction measurements were performed on a D8-ADVANCE (BRUKER, U.S.A.) X-ray diffractometer in steps of 0.02°using CuKa radiation as X-ray source.…”

Solid-state encapsulation of Ag and sulfadiazine on zeolite Y carrier

“…The substitution of silicon by aluminum atoms in the zeolite framework requires the presence of charge compensating counter-ions, usually H + or transition metal elements, which impart unique ion-exchange properties [12]. Because of these properties, they have been used to control release of supported silver species with bactericidal action and also for drug delivery in model systems [13,14].…”