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•mTHPC easily forms 1:2 inclusion complexes with β-CDs following 2 step mechanism.•Methylation of β-CD’s core enhances the affinity to mTHPC.•mTHPC aggregation reduce the binding ...constant of the first β-CD molecule.•Corrected binding constant values are several times higher than previously reported.•High binding constants allow the use the β-CDs for mTHPC delivery in PDT.
The interaction between the potent photosensitizer meta-tetrakis(3-hydroxyphenyl)chlorin (temoporfin, mTHPC) and a series of β-cyclodextrins (β-CDs) was investigated using spectroscopic analysis and molecular dynamics simulations. The possibility of improving its poor aqueous solubility with β-CDs was estimated by measuring both equilibrium solubility and association constants. Parameters of binding isotherms revealed that mTHPC strongly interacts with β-CD derivatives, forming 1:2 inclusion complexes in aqueous solution. We demonstrated that apparent binding constants strongly depend on mTHPC concentration due to the porphyrin self-aggregation. The estimated “correct” binding constants demonstrated that completely methylated β-CD exhibits the highest affinity (K = 1.1 × 107 M−1) as compared to randomly methylated β-CD (K = 7.1 × 105 M−1) and 2-hydroxypropyl substituted β-CD (K = 1.7 × 105 M−1). In fine, our results indicate that TM-β-CD should be considered as a potent vector for mTHPC targeted delivery.
This works tries to establish the performance of truncated CI calculations on the evaluation of magnetic coupling parameters with respect to available FCI estimates on a set of carbon-beryllium ...clusters. First-, second- and third-neighbor magnetic coupling constants have been evaluated and many body effective parameters as the cyclic terms. They result from the fitting of the low-lying states to the eigenvalues of an extended Heisenberg Hamiltonian, involving not only two-body isotropic terms but also cyclic terms. SDCI and DDCI calculations have been carried out and their performance compared with FCI ones. The impact of the basis set choice and size-consistency errors have been explored.
The shape and broadening of He lines affects radiative transport in dense, He-rich, stellar atmospheres. At wavelengths inaccessible for direct observation, we rely on theoretical calculations of ...self-broadening to support stellar structure and spectral modeling. In this work, we examine lines of He due to 1s–2p and 2p–3s transitions. The line profiles are analyzed in terms of a unified theory of spectral line broadening using ab initio potential energies that have been recently determined. For temperatures up to 20 000 K, the linear dependence of width and shift on gas density and the non-linear dependence on temperature of the Lorentzian core of the resonance line are described. Beyond the conventional symmetrical Lorentzian core, we show that they are asymmetrical and have significant additional contributions on the short wavelength side. This blue asymmetry is a consequence of maxima in the corresponding He2 potential energy difference curves at short and intermediate internuclear distance. Over a limited range of density and temperature, laboratory measurements in the visible and near infrared can be used to validate the potentials that underlie the spectral line profile theory, which is useful for modeling spectra over the extreme ranges of temperature and density encountered in stellar and planetary atmospheres.
Ab initio quantum-chemistry programs produce and use large amounts of data, which are usually stored on disk in the form of binary files. A FORTRAN library, named Q5Cost, has been designed and ...implemented in order to allow the storage of these data sets in a special data format built with the HDF5 technology. This data format allows the data to be represented as tree structures and is portable between different platforms and operating systems, making code interoperability and communication much easier. The libraries have been used to build many interfaces among different quantum chemistry codes, and the first scientific applications have been realized. This activity was carried out within the COST in Chemistry D23 project “MetaChem”, in the Working Group “A meta-laboratory for code integration in ab initio methods”.
From explicit solvent molecular dynamics simulations, we probe the existence of two stable and competitive interaction modes between an alternating poly(dA-dT) decamer and benzophenone: a minor ...groove adduct and a double insertion structure in which the central base pair is ejected, with hydrogen bonding with proximal groups, locking the DNA-drug complex. The extensive analysis of non-covalent interactions provides a rationale for the existence of this mode, never reported yet between DNA and any organic photosensitizer. We evidence a highly characteristic signature in our simulated circular dichroism spectra that may provide useful guidance for the future experimental efforts, as well as for theoretical investigations aiming at elucidating the energy transfer mechanism between benzophenone and thymines
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•A new electrochemical sensor for the rapid identification of THC and CBD is developed.•The sensor consists of a screen-printed electrode modified with carbon black.•Carbon black ...guarantees electrocatalytic oxidation of THC and CBD.•The selective identification of THC and CBD is based on PCA of the voltammetric signals.•THC is measured even in presence of high concentration of CDB.
The widespread diffusion of products deriving from Cannabis sativa L. led to the necessity of rapid and reliable methods for the identification of samples containing Δ9-tetrahydrocannabinol (THC), the psychoactive component of the plant, which imparts mental distortions and hallucinations. Although some efficient electrochemical sensors have been already proposed for such a purpose, they do not consider that the plant may also contain huge amounts of cannabidiol (CBD), which possesses an electroactive moiety quite similar to that of THC. The definition of both THC and CBD concentration is at the basis of discrimination between recreational-type and fibre-type cannabis samples; detection of these species is not only important in vegetable samples but also in relevant commercial products and in biological fluids. We proposed here a screen-printed electrode coated with a layer of carbon black for the rapid identification of samples containing THC irrespectively of the simultaneous presence of CBD. The most performing carbon black typology used for such a purpose was chosen among various commercial products tested on the basis of preliminary tests performed on 1,3-dihydroxybenzene, constituting the redox active moiety of cannabinoids. The voltammetric responses collected in various solutions containing different amount of THC and CBD were initially elaborated by Principal Component Analysis, assessing the possibility of identifying samples with similar concentrations of THC irrespectively of the CBD concentration values, and vice-versa. Afterwards a preliminary Partial Last Square regression was performed to evaluate the possibility of a quantitative analysis of both THC and CBD. This approach suggests the possibility of using the sensor proposed to screen samples containing THC even in the presence of high amounts of CBD.
This study of the self-broadening of the 728 nm He line is performed in order to establish similarities and differences to the self-broadening of the triplet 3s-2p line at 706 nm. In a previous work ...we presented the first calculations of He-He collisional profiles at 706nm due to the triplet 3s-2p transition in a unified line shape semi-classical theory using ab-initio molecular potentials. The excellent agreement between experimental and theoretical determinations of the near wing of the line profiles established the accuracy of the interaction potentials. New ab-initio potentials for the singlet 3s-2p transitions allow us to extend our previous study to the line at 728 nm.
Guanine quadruplexes (G4s) play essential protective and regulatory roles within cells, influencing gene expression. In several gene-promoter regions, multiple G4-forming sequences are in close ...proximity and may form three-dimensional arrangements. We analyze the interplay among the three neighboring G4s in the c-KIT proto-oncogene promoter (WK1, WSP, and WK2). We highlight that the three G4s are structurally linked and their cross-talk favors the formation of a parallel structure for WSP. Relying on all-atom molecular dynamic simulations exceeding the μs time scale and using enhanced sampling methods, we provide the first computationally resolved structure of a well-organized G4 cluster in the promoter of a crucial gene involved in cancer development. Our results indicate that neighboring G4s influence their mutual three-dimensional arrangement and provide a powerful tool to predict and interpret complex DNA structures that can ultimately be used as a starting point for drug discovery.
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