Abstract: We have studied the complexation between an adamantane derivative labelled with the fluorescent probe Alexa 488 and the three natural cyclodextrins (-, - and -CD) by Fluorescence Correlation Spectroscopy (FCS), demonstrating the ability of this technique to detect association and to determine the corresponding equilibrium constants with no need for changes in the fluorescence properties of the guest. At low CD concentrations the observed increase of the diffusion time of the probe is mainly due to the complexation of the adamantyl moiety, but further changes are observed when increasing CD concentration that are attributed to the formation of CD aggregates. These aggregates appear at quite low CD concentrations and seem to be formed by a small number of CD molecules. These results show the potential of FCS for the study of CD self-assembly, a recently-recognized phenomenon that could be used to improve certain applications of CDs.

Abstract: In this work, the Tetracarboxyphenylporphyrin Covalently Bound to Silica was used as adsorbent to remove Crystal Violet (CV) from aqueous solution. Silica gel immobilizing Tetracarboxyphenylporphyrin (TCPP) chromophore was prepared by the reactions of 3-aminopropyl silica gel (SiO₂-NH₂) with the TCPP. The 3-aminopropyl silica gel (SiO₂-NH₂) was selected as the carrier because of its ability to immobilize the functional groups through a covalent bond. Micrometer-sized SiO₂-NH₂ beads were prepared by reacting silica gel with 3-aminopropyl(triethoxy)silane (H₂N(CH₂)₃Si(OEt)₃). The immobilization of TCPP chromophores on SiO₂-NH₂ was performed by the sol-gel method. The bond formation was confirmed by the appearance of an amide bond at 1650 and 1539 cm⁻¹ in the FT-IR spectra. The SiO₂-NH₂-TCPP was used as adsorbent for removing Crystal Violet from aqueous solutions. The dye adsorption experiments were carried out by using bath procedure. UV-visible absorption spectroscopy was used to record the adsorption behavior. The pH effects, the contact time and the initial dye concentration were changed to obtain the best experimental conditions. The dye adsorption equilibrium was rapidly attained after 25 min of contact time. The experimental data were best fitted to isotherm models.

Abstract: A molecularly imprinted solid-phase extraction (MISPE) procedure based on precipitation polymerization was developed for the simultaneous extraction of dexamethasone (DM) and its structural isomer, betamethasone (BM), from biological matrices. A DM-imprinted polymer was synthetized using methacrylic acid as monomer and divinylbenzene as cross-linker, and the porogen was a mixture of acetonitrile and toluene (3:1). After removal of the template, loading, washing and elution steps were optimized. The maximun recovery of DM and BM was achieved when loading with toluene and washing with 5% acetonitrile in toluene, and eluting with 1% acetic acid in methanol.

Abstract: β-cyclodextrin―citric acid derivatives were synthesized trough heating of mixture of citric acid, cyclodextrin and Na₂HPO₄ as a catalyst. The degree of substitution of the derivatives was estimated by determination of citric acid by HPLC in the samples hydrolysates. Sorption properties of β-cyclodextrin―citric acid derivatives were determined using spectrophotometric method with methyl orange as a model sorbate. Sorption properties of β-cyclodextrin―citric acid derivatives were compared to native β-cyclodextrin.

Abstract: The conducting protonated polyaniline/ hollow MnFe₂O₄ nanocomposite was successfully synthesized in situ through self assembly polymerization. The core-shell of MnFe₂O₄ hollow spheres were fabricated by template polymerization, at first, the ferrite nanoparticles were synthesized as the shell and coated on the surface of functionalized polystyrene spheres as the core, subsequently, by calcination method the core polymer was removed. The ferrite nanoparticles were combined with PANI by assisting of dodecyl benzene sulfonic acid as doping agent under ultrasonic waves. The difference between the spectra of FT-IR for the ferrite nanoparticles-coated PS spheres and MnFe₂O₄ hollow spheres show the elimination of organic template after calcinations. The image of scanning electron microscopy (SEM) exhibit the ferrite spheres as nanoporous with size holes of 40 nm approximately. Also the magnetic properties of the nanocomposite and MnFe₂O₄ were characterized on a vibrant sample magnetometer (VSM) with maximum saturation magnetization values of 1.59 emu/g and 66.7 emu/g respectively. X-ray diffraction (XRD) pattern of the ferrite sample is well in agreement with the standard pattern of the cubic structure. Atomic force microscopy (AFM) was used for surface morphology analysis. UV–Visible absorption spectroscopy recorded the adsorption behavior of the solution after treatment with synthesized nanocomposite showing the adsorption capacity of Crystal violet dye.