Enhanced floating and intragastric release of 5-Flourouracil through sesame oil entrapped gellan composite hydrogel beads

Background: 5-Fluorouracil is an anti-metabolite compound used for several years as an anti-tumor drug. The development of a gastroretentive drug delivery system of 5-Fluorouracil may have advantages since they retain in the stomach for an extended time and release the drug in a sustained manner which ultimately enhances the absorption of the drug and consequently the bioavailability. Objective: The objective of the present work was to prepare a sesame oil-entrapped gellan gum hydrogel bead for controlled stomach specific delivery of 5-Fluorouracil. Methods: Sesame oil-entrapped gellan gum hydrogel bead was prepared by ionotropic gelation method. The developed hydrogels were characterized by SEM, FTIR, DSC, and XRD. The entrapment efficiency, floating ability, swelling and drug release in vitro were also determined. Results: Electrostatic interaction between the carboxylic group of polymers and Ca++ was confirmed by FTIR analysis. The SEM photograph of the hydrogel beads portrayed an approximately spherical shaped structure. DSC thermogram and XRD spectra exhibited the molecular dispersion of the drug inside the hydrogel beads. The developed beads of 5-Fluorouracil floated in pH 1.2 buffer solutions for a prolonged time period and the duration of floating was improved significantly with increasing the concentration of oil. The developed formulations showed controlled release of drug and incorporation of oil retarded the release of the drug. Fickian and non-Fickian mechanism of drug transport was observed from the prepared hydrogel beads. Conclusion: Overall, the oil-entrapped gellan matrices could be used for the intragastric delivery of 5-Fluorouracil to treat stomach cancer.

A Post-HF Approach to the Sunscreen Octyl Methoxycinnamate

Octyl methoxycinnamate (OMC) is a commercial sunscreen with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as UVB filter. In particular, the trans (E) form - which is considered so far the most stable isomer - converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree-Fock approaches (CCSD, CCSD(t) and CCSD+T(CCSD)) on ground state OMC geometries optimized at the MP2 level we show that the cis and trans form of the gas-phase OMC molecule have comparable stability. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded, more compact structure than the trans isomer.<br>

A Post-HF Approach to the Sunscreen Octyl Methoxycinnamate

Octyl methoxycinnamate (OMC) is a commercial sunscreen with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as UVB filter. In particular, the trans (E) form - which is considered so far the most stable isomer - converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree-Fock approaches (CCSD, CCSD(t) and CCSD+T(CCSD)) on ground state OMC geometries optimized at the MP2 level we show that the cis and trans form of the gas-phase OMC molecule have comparable stability. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded, more compact structure than the trans isomer.<br>

A Post-HF Approach to the Sunscreen Octyl Methoxycinnamate

Octyl methoxycinnamate (OMC) is a commercial sunscreen with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as UVB filter. In particular, the trans (E) form - which is considered so far the most stable isomer - converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree-Fock approaches (CCSD, CCSD(t) and CCSD+T(CCSD)) on ground state OMC geometries optimized at the MP2 level we show that the cis and trans form of the gas-phase OMC molecule have comparable stability. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded, more compact structure than the trans isomer.<br>

On the Higher-Order Static Polarizabilities and Dispersion Coefficients of the Fullerenes: An Ab Initio Study

<div>In this work, we used finite-field derivative techniques and density functional theory (DFT) to compute the static isotropic polarizability series (<i>i.e.</i>, dipole, quadrupole, and octupole ) for the C₆₀-C₈₄ fullerenes and quantitatively assess the intrinsic non-additivity in these fundamental response properties. Critical analysis of the derived effective scaling laws provides new insight into how the electronic structure of finite-sized fullerenes---a unique dichotomy of electron confinement and delocalization effects due to their quasi-spherical cage-like structures and encapsulated void spaces---simultaneously limits <i>and</i> enhances their quantum mechanical response to electric field perturbations. Corresponding molecular dispersion coefficients needed to describe the non-trivial van der Waals (vdW) interactions in fullerene-based systems were obtained by inputting the polarizabilities into the hollow sphere model within the modified single-frequency approximation. </div><div>Using first-order perturbation theory in conjunction with >140,000 DFT calculations, we also computed the non-negligible zero-point vibrational contributions (zpvc) to the dipole polarizability in C₆₀ and C₇₀, thereby enabling direct comparison between theory and experiment for these quintessential nanostructures.</div>

On the Higher-Order Static Polarizabilities and Dispersion Coefficients of the Fullerenes: An Ab Initio Study

<div>In this work, we used finite-field derivative techniques and density functional theory (DFT) to compute the static isotropic polarizability series (<i>i.e.</i>, dipole, quadrupole, and octupole ) for the C₆₀-C₈₄ fullerenes and quantitatively assess the intrinsic non-additivity in these fundamental response properties. Critical analysis of the derived effective scaling laws provides new insight into how the electronic structure of finite-sized fullerenes---a unique dichotomy of electron confinement and delocalization effects due to their quasi-spherical cage-like structures and encapsulated void spaces---simultaneously limits <i>and</i> enhances their quantum mechanical response to electric field perturbations. Corresponding molecular dispersion coefficients needed to describe the non-trivial van der Waals (vdW) interactions in fullerene-based systems were obtained by inputting the polarizabilities into the hollow sphere model within the modified single-frequency approximation. </div><div>Using first-order perturbation theory in conjunction with >140,000 DFT calculations, we also computed the non-negligible zero-point vibrational contributions (zpvc) to the dipole polarizability in C₆₀ and C₇₀, thereby enabling direct comparison between theory and experiment for these quintessential nanostructures.</div>

Molecular Dispersion of Starch as a Crucial Parameter during Size-Exclusion Chromatography

Starch, α-polyglucan consisting of a large number of anhydroglucose units joined by α-1,4- and α-1,6-glycosidic bonds, seems to be characterized by a simple structure when compared to other natural polymers. Nevertheless, starches of various botanical origins have different physicochemical properties that are related to the differences in molecular and supramolecular structure of this polymer. In terms of the functional value of starch, the behavior of its macromolecules in solution is the most important result of its structural features. Extremely high molecular mass is the fundamental structural property of starch. Water, considered simply as a solvent for solubilization, does not provide molecular dispersion of starch without its degradation. The objectives of this study are to characterize the suitability of a new aqueous media (urea/NaOH) for enhancing the dispersion of native corn and potato starches and its effect on the consequent size-exclusion chromatography (SEC) analysis. The results were referred to other aqueous base solvents used for dispersing starch (NaOH and KOH). The samples were separated using SEC with triple detection and phosphate buffer (pH 8.0) with urea as the eluent. The characteristics of tested normal and waxy starches were compared. The results revealed that urea/NaOH did not degrade starch during the dispersion process. The recovery of starches, however, was not higher than 42%. These results prove that while the urea/NaOH solvent allows to obtain cold-water-soluble starch, the degree of disintegration of the intramolecular interactions of amylopectin chains is still insufficient.