Comparative study of titanium dioxide to improve the quality of finished cosmetic products.

OBJECTIVE: Titanium dioxide (TiO2 ) pigments (pure) or with a hydrophobic coating of triethoxycaprylylsilane (TECSi) used in cosmetics. Using different methods, we studied properties of commercially available pure and coated pigment. We determined the elemental composition of pigments that differ in their behaviour in a cosmetic formulation. The significant differences in the coating composition were revealed. METHODS: UV-Vis absorption spectroscopy allowed us to investigate the pigment purity and determined the polymorph form in pigments. FTIR was employed to identify functional groups present in the samples with the modified surface. XRD, DLS, TEM and DCS were applied to characterize particle size and morphology. The experiment of ED-XRF method was used to determine the elemental composition of pigments that differ in their behaviour in a cosmetic formulation. RESULTS: UV-Vis spectroscopy was used to detect organic pollutants in particular batches, which were not detected in the cases of the tested samples. Solid UV-Vis spectroscopy and XRD revealed which crystalline form of TiO2 is present in pigments. TEM and DLS methods were used to characterize particle size and morphology as well as DCS method, which provide more accurate information about form (separated or clustered particles) of pigments' particles in suspensions. Based on FTIR spectra, the presence of a coating in the raw material was identified, and the tell-tale signal of the silane group. On the contrary, spectroscopy of washed-out product can identify the well or poorly modified pigment. Applying ED-XRF, it turned out that the content of silicon (and consequently of the TECSi) was lower than that declared by the manufacturer. CONCLUSION: Our data indicate how we can recognize poorly coated pigments in raw material. The results show that ED-XRF method is nondestructive, effective and fast, hence, can be successfully introduced into preproduction pigment control in cosmetic industry.

OBJECTIF: Les pigments de dioxyde de titane (TiO2 ) (pur) ou avec un revêtement hydrophobe de triéthoxycaprylylsilane (TECSi) sont utilisés dans les cosmétiques. En utilisant différentes méthodes, nous avons étudié les propriétés des pigments purs et enrobés disponibles dans le commerce. Nous avons déterminé la composition élémentaire des pigments qui diffèrent dans leur comportement dans une formulation cosmétique. Les différences significatives dans la composition de l'enrobage ont été révélées. METHODES: La spectroscopie d'absorption UV-Vis nous a permis d'étudier la pureté des pigments et de déterminer la forme polymorphe des pigments. L'IRTF a été utilisé pour identifier les groupes fonctionnels présents dans les échantillons à la surface modifiée. XRD, DLS, TEM et DCS ont été appliqués pour caractériser la taille et la morphologie des particules. L'expérience de la méthode ED-XRF a été utilisée pour déterminer la composition élémentaire des pigments qui diffèrent dans leur comportement dans une formulation cosmétique. RÉSULTATS: La spectroscopie UV-Vis a été utilisée pour détecter des polluants organiques dans des lots particuliers, qui n'ont pas été détectés dans les cas des échantillons testés. La spectroscopie UV-Vis et la XRD ont révélé quelle forme cristalline de TiO2 est présente dans les pigments. Les méthodes TEM et DLS ont été utilisées pour caractériser la taille et la morphologie des particules ainsi que la méthode DCS qui fournit des informations plus précises sur la forme (particules séparées ou agglomérées) des particules de pigments dans les suspensions. Sur la base des spectres FTIR, la présence d'un revêtement dans la matière première a été identifiée, ainsi que le signal révélateur du groupe silane. D'autre part, la spectroscopie du produit délavé permet d'identifier le pigment bien ou mal modifié. En appliquant l'ED-XRF, il s'est avéré que la teneur en silicium (et par conséquent du TECSi) était inférieure à celle déclarée par le fabricant. CONCLUSION: Nos données indiquent comment nous pouvons reconnaître les pigments mal enrobés dans la matière première. Les résultats montrent que la méthode ED-XRF est non-destructive, efficace et rapide, et qu'elle peut donc être introduite avec succès dans le contrôle des pigments en pré-production dans l'industrie cosmétique.

Thermodynamic Studies of Interactions between Sertraline Hydrochloride and Randomly Methylated ß-Cyclodextrin Molecules Supported by Circular Dichroism Spectroscopy and Molecular Docking Results.

The interaction between sertraline hydrochloride (SRT) and randomly methylated ß-cyclodextrin (RMßCD) molecules have been investigated at 298.15 K under atmospheric pressure. The method used-Isothermal Titration Calorimetry (ITC) enabled to determine values of the thermodynamic functions like the enthalpy (ΔH), the entropy (ΔS) and the Gibbs free energy (ΔG) of binding for the examined system. Moreover, the stoichiometry coefficient of binding (n) and binding/association constant (K) value have been calculated from the experimental results. The obtained outcome was compared with the data from the literature for other non-ionic ßCD derivatives interacting with SRT and the enthalpy-entropy compensation were observed and interpreted. Furthermore, the connection of RMßCD with SRT was characterized by circular dichroism spectroscopy (CD) and complexes of ßCD derivatives with SRT were characterized through the computational studies with the use of molecular docking (MD).

The Interaction of Heptakis (2,6-di-O-Methyl)-ß-cyclodextrin with Mianserin Hydrochloride and Its Influence on the Drug Toxicity.

One tetracyclic antidepressant, mianserin hydrochloride (MIA), has quite significant side effects on a patients' health. Cyclodextrins, which are most commonly used to reduce the undesirable features of contained drugs within their hydrophobic interior, also have the potential to alter the toxic behavior of the drug. The present paper contains investigations and the characteristics of interaction mechanisms for MIA and the heptakis (2,6-di-O-methyl)-ß-cyclodextrin (DM-ß-CD) system, and evaluated the effects of the complexation on MIA cytotoxicity. In order to assess whether there was an interaction between MIA and DM-ß-CD molecules, isothermal titration calorimetry (ITC) have been chosen. Electrospray ionization mass spectrometry (ESI-MS) helped to establish the complex stoichiometry, and circular dichroism spectroscopy was used to describe the process of complex formation. In order to make a wider interpretative perspective, the molecular docking results have been performed. The viability of Chinese hamster cells were investigated in the presence of DM-ß-CD and its complexes with MIA in order to estimate the cytotoxicity of the drug and the conjugate with the chosen cyclodextrin. The viability of B14 cells treated with MIA+DM-ß-CD is lower (the toxicity is higher) than with MIA alone, and no protective effects have been observed for complexes of MIA with DM-ß-CD in any ratio.

Quantum chemical study and isothermal titration calorimetry of ß-cyclodextrin complexes with mianserin in aqueous solution.

ß-Cyclodextrin (ß-CD) is studied as a carrier of the drug mianserin (MIA). ß-CD with MIA adducts with 1 : 1 and 2 : 1 stoichiometry are investigated in vacuo and in water using quantum chemical methods: PM6 and B3LYP/6-31G(d,p). An effect of the dispersion correction GD2 and the basis set superposition error on the complexation energies is also evaluated. Additionally, the interaction between MIA hydrochloride and ß-CD in aqueous solution at 298.15 K is examined experimentally by isothermal titration calorimetry. Interaction parameters, such as the binding constant, enthalpy, entropy and Gibbs free energy, are presented. Analysis of the obtained data led to the following conclusions: the interaction of MIA with ß-CD is rather strong; there is no significant energetic difference between the 1 : 1 complexes of ß-CD with S-MIA and R-MIA enantiomers; the 2 : 1 (ß-CD : MIA) adduct is energetically more favorable than 1 : 1; the complex formation of MIA + ß-CD is enthalpy and entropy driven.

Generation-dependent effect of PAMAM dendrimers on human insulin fibrillation and thermal stability.

We have studied the effect of polyamidoamine (PAMAM) dendrimers of various generations on the thermal stability and fibrillation of human insulin. Thermostability of human insulin used differential scanning calorimetry (DSC), which showed two phase-transitions for insulin at 60 and 82°C. After adding dendrimers at 0.6 µmol/l, the first peaks disappeared and the second peaks were higher. We posited that, in the presence of dendrimers, the dimers in the solution were transformed into hexamers. The effect of dendrimers on insulin fibrillation was monitored by measuring ThT fluorescence, and visualization of insulin fibrils by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The effect of PAMAM dendrimers on insulin fibrillation was strongly dependent on the dendrimers generation and dendrimer:protein ratio.