A quartz crystal microbalance-assisted method for the assessment of iodine content in organoiodines

Introduction: A new experimental quantitative approach for evaluating iodine content in organoiodine compounds has been proposed, based on the quartz crystal microbalance (QCM) method. This approach relies on following the time behavior of the resonance frequency of the quartz plate under temperature activation of iodine-containing analyte deposited on its surface.Materials and Methods: We have applied the QCM method and the pharmacopoeial titrimetric method.Results and Conclusion: From the mass variations observed, the quantity of emitted iodine is precisely obtained, which readily delivers its initial content in the studied sample. The obtained value corresponds exactly to the theoretical prediction, in contrast to the value obtained by applying the conventional pharmacopoeial metrics

Diltiazem-loaded Eudragit RS 100 microparticles for drug delivery: the challenge of viscosity

Strongly shape-dependent viscosity has been found in drug loaded and `empty` polymeric microspheres (drug delivery systems) made of pharmacopoeial Eudragit RS 100 representative. The dramatically increased viscosity of a layer of spherical particles deposited on the gold electrode surface of quartz resonators from water suspension leads to a large dynamic resistance and inability to sustain stable oscillations in a frequency measuring circuit. The viscosity is also affected by loading the polymer matrix with Diltiazem. Its adverse impact is removed by exposing the deposed layer to acetone vapor leading to `dissolving` the investigated spheres and changing their shape to a thin layered one

Growth and toxic gas sensing properties of poly(urethaneimide) thin films

In this work we present a study on the growth and the gas sensing properties of poly(urethane imide) thin films. We first deeply characterized by atomic force microscopy (AFM) the nanostructuration of the poly(urethane imide) holding different amine groups. We further studied the interaction between highly toxic gases such as hexamethyleneimine (HMI) and pyridine and the polymer by using an unconventional method based on Quartz Crystal Microbalance (QCM) measurement. We showed for the first time that weak interactions, i.e. hydrogen bonding between the gas molecules and the polymer film allow the diffusion of the gas molecule deep in the polymeric film and the recovery of the film once the gas molecules leave the sensor. This first work paves a new way for the design of a completely recoverable sensor able to detect highly toxic gases for environmental concern

Ammonio Methacrylate Copolymer (Type B)-Diltiazem Interactions in Solid Dispersions and <i>Microsponge</i> Drug-Delivery Systems

This paper presents a complex analytical study on the distribution, solubility, amorphization, and compatibility of diltiazem within the composition of Eudragit RS 100-based particles of microspongeous type. For this purpose, a methodology combining attenuated total reflectance Fourier transform infrared (ATR-FTIR) absorption spectroscopy, differential scanning calorimetry (DSC), scanning electron microscopy with energy-dispersive X-ray microanalysis (SEM-EDX), and in vitro dissolution study is proposed. The correct interpretation of the FTIR and drug-dissolution results was guaranteed by the implementation of two contrasting reference models: physical drug–polymer mixtures and casting-obtained, molecularly dispersed drug–polymer composites (solid dispersions). The spectral behavior of the drug–polymer composites in the carbonyl frequency (νCO) region was used as a quality marker for the degree of their interaction/mutual solubility. A spectral-pattern similarity between the microsponge particles and the solid dispersions indicated the molecular-type dispersion of the former. The comparative drug-desorption study and the qualitative observations over the DSC and SEM-EDX results confirmed the successful synthesis of a homogeneous coamorphous microsponge-type formulation with excellent drug-loading capacity and “controlled” dissolution profile. Among them, the drug-delivery particles with 25% diltiazem content (M-25) were recognized as the most promising, with the highest population of drug molecules in the polymer bulk and the most suitable desorption profile. Furthermore, an economical and effective analytical algorithm was developed for the comprehensive physicochemical characterization of complex delivery systems of this kind