J-complexes of retinol formed within the nanoparticles prepared from microemulsions (original) (raw)

Polyethylenimine Complexes with Retinoic Acid: Structure, Release Profiles, and Nanoparticles

Macromolecules, 2000

In this paper we discuss the preparation of complexes formed by polyethylenimine (PEI) and retinoic acid. The molecular weights of the PEIs were 600, 2000, 25 000, and 750 000 g/mol. All complexes form smectic A-like structures whose orders decrease with increasing molecular weight. The complexes in the bulk material obey Porod's law. Macroscopically oriented multilayer films of the complexes were prepared in a single-step procedure by spin coating and were characterized by X-ray reflectivity. The release of retinoic acid from the films was investigated by FTIR and surface tension measurements. It was found that the release from the complexes with the high molecular weight PEIs is faster than that from the complexes with low molecular weight. Steric stabilized nanoparticles of the complexes were prepared with sizes ranging from 170 to 580 nm by using Poloxamer 188 as the dispersing agent in aqueous media. Their characterization was carried out using dynamic light scattering and atomic force microscopy. It was found that the particle sizes decreased with the increasing molecular weight of the PEIs. Further, the particle structure became more compact with the increasing molecular weight of the PEIs. The particles of the complexes with the lowest molecular weight were assumed to be doughnutshaped (toroids).

Absorption and Fluorescence Features of an Amphiphilic meso-Pyrimidinylcorrole: Experimental Study and Quantum Chemical Calculations

The journal of physical chemistry. A, 2017

Corroles are emerging as an important class of macrocycles with numerous applications because of their peculiar photophysical and metal chelating properties. meso-Pyrimidinylcorroles are easily deprotonated in certain solvents, which changes their absorption and emission spectra as well as their accessible supramolecular structures. To enable control over the formation of supramolecular structures, the dominant corrole species, i.e., the deprotonated form or one of the two NH-tautomers, needs to be identified. Therefore, we focus in the present article on the determination of the UV-vis spectroscopic properties of the free-base NH-tautomers and the deprotonated form of a new amphiphilic meso-pyrimidinylcorrole that can assemble to supramolecular structures at heterointerfaces as utilized in the Langmuir-Blodgett and liquid-liquid interface precipitation techniques. After quantification of the polarities of the free-base NH-tautomers and the deprotonated form by means of quantum chem...

Theoretical Studies of Milk: Solvent Effects on the Molecular Properties of Retinoid Compounds

QUARKS: Brazilian Electronic Journal of Physics, Chemistry and Materials Science, 2020

We discuss here the role of environment in the structural and spectroscopic properties of vitamin A in its retinoid forms: retinol and retinal. The analyzed compounds show three singlet excited states exhibiting wavelengths between 472 and 273 nm according to the medium. The transitions involve HOMO, LUMO, HOMO-1, LUMO and HOMO, LUMO+1 orbitals.

DESIGN & EVALUATION OF NOVEL RETINOL- ENCAPSULATED CHITOSAN NANOPARTICLES

The aim of this study was to encapsulate retinol into chitosan nanoparticles and reconstitute it into aqueous solution. Retinol-encapsulated chitosan nanoparticles were prepared for application of cosmetic and pharmaceutical applications. Retinol-encapsulated chitosan nanoparticle has a spherical shape and its particle sizes were around 50–200 nm according to the drug contents. Particle size was increased according to the increase of drug contents. Solubility of retinol is able to increase by encapsulation into chitosan nanoparticles more than 1600-fold. It was suggested that retinol was encapsulated into chitosan nanoparticles by ion complex as a result of FT-IR spectra. Specific peak of chitosan at 1590 cm −1 was divided to semi-doublet due to the electrostatic interaction between amine group of chitosan and hydroxyl group of retinol. At 1 H NMR spectra, specific peaks of retinol disappeared when retinol-encapsulated chitosan nanoparticles were reconstituted into D 2 O while specific peaks both of retinol and chitosan appeared at D 2 O/DMSO (1/4, v/v) mixture. XRD patterns also showed that crystal peaks of retinol were disappeared by encapsulation into chitosan nanoparticles. Retinol-encapsulated nanoparticles were completely reconstituted into aqueous solution as same as original aqueous solution and zeta potential of reconstituted chitosan nanoparticles was similar to their original solution. At HPLC study, retinol was stably and efficiently encapsulated into chitosan nanoparticles.

Mechanisms of Electron Injection from Retinoic Acid and Carotenoic Acids to TiO 2 Nanoparticles and Charge Recombination via the T 1 State As Determined by Subpicosecond to Microsecond Time-Resolved Absorption Spectroscopy: Dependence on the Conjugation Length

The Journal of Physical Chemistry B, 2005

To examine the mechanisms of electron injection to TiO 2 in retinoic acid (RA) and carotenoic acids (CAs), including RA5, CA6, CA7, CA8, CA9, and CA11 having the number of conjugated double bonds n ) 5, 6, 7, 8, 9, and 11, respectively, their subpicosecond time-resolved absorption spectra were recorded free in solution and bound to TiO 2 nanoparticles in suspension. The time-resolved spectra were analyzed by singularvalue decomposition (SVD) followed by global fitting based on an energy diagram consisting of the 3A g -, 1B u -, 1B u + , and 2A gsinglet excited states, whose energies had been determined as functions of 1/(2n + 1) by the use of carotenoids with n ) 9-13. It was found that electron injection took place from both the 1B u + and 2A gstates in RA5, CA6, CA7, and CA8, whereas only from the 1B u + state in CA9 and CA11. The electron-injection efficiencies were determined, by the use of the relevant time constants determined by the SVD and global-fitting analyses, to be in the following order:

Binding of all- trans retinoic acid to human serum albumin: Fluorescence, FT-IR and circular dichroism studies

International Journal of Biological Macromolecules, 2006

All-trans retinoic acid derived from vitamin A is an essential component for the modulation of angiogenesis, the process of blood vessel formation. We have investigated the binding of all-trans retinoic acid to the carrier protein, human serum albumin (HSA) under physiological conditions. Fluorescence quenching methods in combination with Fourier transform infrared (FT-IR) spectroscopy and circular dichroism (CD) spectroscopy were used for the biophysical studies. The binding parameters were determined by a Scatchard plot and the results found to be consistent with those obtained from a modified Stern–Volmer equation. From the thermodynamic parameters calculated according to the van’t Hoff equation, the enthalpy change ΔH0 and entropy change ΔS0 are found to be 106.17 and 106.14 J/mol K, respectively. These values suggest that apart from hydrophobic interactions electrostatic interactions are present. Changes in the CD spectra and FT-IR spectra were observed upon ligand binding along with a significant degree of tryptophan fluorescence quenching on complex formation. Docking studies performed substantiated our experimental findings and it was observed that all-trans retinoic acid hydrogen bonded with Trp 214 and Asp 451 residues of subdomain IIA and IIIA of HSA, respectively.

Aggregation in Nanobundles and the Effect of Diverse Environments on the Solution-Phase Photochemistry and Photophysics of− Re (CO) 3L (L) 1, 10- …

Supramol. Chem, 2003

The UV−vis spectroscopy and photochemical properties of {(vpy-[Re(CO) 3 (2,2′-bpy)]) m (vpy-[Re(CO) 3 (phen)]) n (vpy) p }-(CF 3 SO 3 ) m+n }, vpy ) 4-vinylpyridine, m ) 131, n ) 131 or m ) 200, n ) 150, and m + n + p ) 600, were investigated in solution phase. The polymers exist in solution as aggregates of polymer strands with radii as large as ∼10 2 nm. Given the size of the poly-vpy backbone, the aggregates must contain a large number of strands. The luminescence spectrum exhibits a strong resemblance to the emission spectrum of {(vpy-[Re(CO) 3 (phen)]) 200 -(vpy) 400 }(CF 3 SO 3 ) 200 . The existence of Re(I) chromophores in diverse environments was shown by the intrinsic kinetics of the luminescence, the decay kinetics of the MLCT excited states observed by time resolved-absorption spectroscopy, and the quenching of the luminescence by various quenchers. Redox reactions of the MLCT excited states with the quenchers were responsible for the luminescence quenching. While static quenching resulted when Cu(II) and Fe(III) EDTA complexes were the quenchers, a dynamic quenching resulted with Fe(CN) 6 4or 2,2′,2′′triethanolamine, TEOA. The photochemical and photophysical properties of the mixed-pendant polymers have been discussed in terms of arrays of MLCT excited states whose energies are determined by the diverse environments of the Re(I) chromophores. Conversions (with and without radiation) of the upper-energy MLCT excited states to the ground state and lower-energy MLCT excited states and the latter excited state to the ground state account for the experimental results.

Macromolecular Chemistry and Physics

Polysaccharide based nanoparticles (NP) have demonstrated a unique potential for biomedical and biotechnological applications. Various functionalities can be covalently linked to these NP, however, physical entrapment of functional compounds is still a highly desired approach, e.g., for drug delivery. Using different dyes, it is demonstrated how hydrophobic compounds can be incorporated into composite particles derived from cellulosic esters and how the particle properties are affected by the composition. The dye loaded NP are studied by UV-vis spectroscopy to gain insight in the interaction of the hydrophobic compounds with the cellulosic matrix. By using functional cellulose derivatives, in particular carboxylate group bearing acetate phthalates, it is possible to introduce reactive moieties on the NP surface that can be exploited for coupling additional functionalities such as antibodies. By this approach, NP can be obtained that are well suited as dye labels in immunoassay applications.

Towards a quantitative determination of retinoids complexed to cyclodextrin: the diphenyl polyene model

Analytica Chimica Acta, 1994

Retinoids are prone to oxidation or isomerization and are therefore difficult to quantify in complex media. It is expected that their inclusion in cyclodextrins would increase their stability and maintain or improve their emission properties. It seems then that such complexed retinoids would lend themselves to a better quantification. A methodology has been developed with 1,6-diphenyl-1,3,5-hexatriene (DPH), a model molecule for retinoids, to follow the formation of the complex. The latter is insoluble in cold water and soluble in acetonitrile-water (1 :3, v/v) mixtures. The complexes were detected by fluorescence on thin-layer chromatography plates. Free DPH and the inclusion complex are so well separated that the quantification of the unbound molecule was carried out without interference by means of a charge-coupled device camera. Differences in the absorbances of the free and totally solubilized DPH are used to determine the quantity of included DPH. Preliminary kinetic studies suggest that the oxidation or isomerization of DPH is decreased in the inclusion complex .

Controlled Release of Retinol in Cationic Co-Polymeric Nanoparticles for Topical Application

Cosmetics, 2020

Retinol is a compound used in many skin care formulations to act against skin conditions like acne, wrinkles, psoriasis, and ichthyosis. While retinol is used as an active ingredient, its efficacy is limited by an extreme sensitivity to light and temperature. Retinol can also generate toxicity at high concentrations. Microencapsulation is an alternative method to help overcome these issues. In this study, we develop a new encapsulation of retinol by solvent evaporation using a cationic polymer. We show that our particles have a narrow size distribution (350 nm), can encapsulate retinol with high efficiency, and protect it from oxidation for at least eight weeks. Finally, to demonstrate that the release of retinol from the particles can be controlled, we performed a kinetic study and showed that the particle releases the drug during 18 h.