Calori, Italo RodrigoPinheiro, LukasBraga, GustavoPedroso de Morais, Flavia Amanda...
10页
查看更多>>摘要：Pluronic/lipid mix promises stealth liposomes with long circulation time and long-term stability for pharmaceutical applications. However, the influence of Pluronics on several aspects of lipid membranes has not been fully elucidated. Herein it was described the effect of Pluronics on the structured water, alkyl chain conformation, and kinetic stability of dimyristoylphosphatidylcholine (DMPC) liposomes using interfacial and deeper fluorescent probes along with computational molecular modeling data. Interfacial water changed as a function of Pluronics' hydrophobicity with polypropylene oxide (PPO) anchoring the copolymers in the lipid bilayer. Pluronics with more than 30-40 PO units had facilitated penetration at the bilayer while shorter PPO favored a more interfacial interaction. Low Pluronic concentrations provided long-term stability of vesicles by steric effects of polyethylene oxide (PEO), but high amounts destabilized the vesicles as a sum of water-bridge cleavage at the polar head group and the reduced alkyl-alkyl interactions among the lipids. The high kinetic stability of Pluronic/DMPC vesicles is a proof-of-concept of its advantages and applicability in nanotechnology over conventional liposome-based pharmaceutical products for future biomedical applications. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Three new aza-dipyrrinato ruthenium sensitizers AZA-BPY, AZA-BPY-NCS, and AZA-TER, have been designed and successfully synthesized. We have studied the effect of aza-dipyrrinato ligands on the photo-physical and electrochemical properties. The aza-dipyrrinato ancillary ligand exhibited enhancement in the light-harvesting capability compared to the traditional dipyrrinato ligand by coordinating ruthenium metal. The strong a-donor characteristic of the aza-dipyrrinato ligand showed more adequate properties: red-shift in the absorption extended into the NIR region ( approximate to 1000 nm), and redox potentials compared to our earlier reported dipyrrinato sensitizer (GS3), which are confirmed by the UV-Vis absorption spectroscopy and cyclic voltammetry. All the characteristics features shows that these dyes are a good sensitizer candidate for DSSCs. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Many impressive results have been achieved in the researches and developments of luminescent chromophore materials by combining experimental synthesis and characterization with the cooperative theoretical calculation. However, the existing theoretical studies are usually based on the intrinsic properties of isolated molecules and extend their properties to the whole molecular material directly, which will lead to the persistence of errors and affect the computational design of molecular materials with different morphology. Therefore, the study of multimolecular systems needs to further consider the environmental effects on molecules. This work is based on the calculation of a series of crystalline Ir(III) complexes under background charge conditions to reveal how the surrounding charge affects the photophysical properties of a series of transition metal Ir(III) complex materials. Through this method, the study of crystalline complexes is found to be more authentically reproduced the charge transfer state, energy level, and reorganization energy, etc., and shows the changes of luminescence characteristics and efficiency. The change of the electronic structure of the target molecule would be characterized more comprehensively, thus obtaining more accurate results for the excited states properties of molecular materials. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Under heating conditions, L-Glutamic acid (L-Glu) can be dehydrated to form L-pyroglutamic acid (LPGA), and L-PGA can racemize to form DL-PGA. Here, we characterized this transformation at different temperatures and times by terahertz time domain spectroscopy (THz-TDS). By Powder X-ray diffraction (PXRD), the validity of THz spectroscopy is verified. The results prove that the reaction rate of dehydration and racemization is significantly affected by temperature. The THz spectra divided the reactions into three stages. At 150-155 degrees C, the reaction changes drastically. Furthermore, we found that the absorption intensity at 0.97 and 1.55 THz has a good dependence on the reaction temperature and time, showing a non-linear relationship (R-2 > 0.98). Our findings suggest that the chemical transformation and reaction rate can be sensitively probed by terahertz spectroscopy, which provides a potential method for the quantitative analysis of reaction products. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Photoinduced charge transfer (CT) mechanisms of two Donor-pi-Donor-pi-Acceptor conjugates composed of ferrocene (Fc), zinc-porphyrin (ZnP), and fullerene (C-60) linked by phenylene-acetylene/acetylene during the one- (OPA) and the two-photon absorption (TPA) processes are analyzed theoretically based on the density functional theory calculations and visualization methods to study the effects of linkage between the two donors on the excitation characteristics. The change of bridge affects the efficiency of superexchange CT from Fc to ZnP in the OPA process. The one-photon excitations are dominated by local transitions of ZnP and Fc, and there is almost no efficient CT from the donors to the acceptor for both the two researched structures. In contrast, the advantage of superexchange CT from ZnP to C-60 becomes much larger than the other transition forms during the TPA process when the linkage between ZnP and Fc is changed from acetylene to phenylene-acetylene. This linkage effect in TPA would have great significance in designing novel optoelectronic devices. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The direct characterization of DNA nanogels at the atomic level is desirable and of great significance, however, has been challenging because of structural complexity and the larger size of nanogels. Herein, we demonstrated a simple, sensitive and reliable SERS (Surface-enhanced Raman spectroscopy)-based approach towards direct monitoring microstructures, such as three types of nanogels crosslinked by DNA G-quadruplex, i-motif and GC duplex. The achievement is attributed to the detection of featured Raman bands corresponding to the formation of Watson-Crick and Hoogsteen hydrogen bonds as well as CC' base pairs. Importantly, this work reveals that the silver nanoparticles attaching on the surface of nanogels can form local `hotspots' and produce high-quality of Raman spectra under the assistance of iodide, aluminum ions and dichloromethane, therefore, shows great potential for wide applications in accurate characterization of various DNA nanostructures. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：This work presents a new method for minoxidil detection based on silver nanoparticle (AgNP) oxidation. Minoxidil, which is a pyrimidine N-oxide, can be reduced to its corresponding pyrimidine via a redox reaction. In this system, acetate buffer serves as a proton source. AgNPs act as electron donors that contribute electrons to the reaction, producing Ag+. Consequently, the sizes and numbers of AgNPs in the system decrease, which results in a decline in their resonance Rayleigh scattering (RRS). By monitoring the RRS intensity at 409 nm, a change in intensity was linearly related to the minoxidil concentration over a concentration range of 0.5 - 5.0 mM. The detection limit was 0.35 mM. This approach is simple and rapid. It is done by directly mixing the drug and AgNPs in an acidic buffer. The reaction was completed within 2 min. This proposed method was successfully utilized for quantification of minoxidil in topical hair-growth formulations. (C) 2022 Published by Elsevier B.V.
查看更多>>摘要：The lattice dynamics of preferentially aligned nanocrystals formed upon drying of aqueous Ba(NO3)(2) solutions in a mesoporous silica glass traversed by tubular pores of approximately 12 nm are explored by Raman scattering. To interpret the experiments on the confined nanocrystals polarized Raman spectra of bulk single crystals and X-ray diffraction experiments are also performed. Since a cubic symmetry is inherent to Ba(NO3)(2), a special Raman scattering geometry was utilized to separate the phonon modes of A(g) and E-g species. Combining group-theory analysis and ab initio lattice dynamics calculations a full interpretation of all Raman lines of the bulk single crystal is achieved. Apart from a small confinement-induced line broadening, the peak positions and normalized peak intensities of the Raman spectra of the nanoconfined and macroscopic crystals are identical. Interestingly, the Raman scattering experiment indicates the existence of comparatively large, similar to 10-20 mu m, single-crystalline regions of Ba(NO3)(2) embedded in the porous host, near three orders of magnitude larger than the average size of single nanopores. This is contrast to the initial assumption of non-interconnected pores. It rather indicates an inter-pore propagation of the crystallization front, presumably via microporosity in the pore walls. (C) 2022 Elsevier B.V. All rights reserved.
Kaplanskiy, M. V.Titova, A. A.Tupikina, E. Yu.Chakalov, E. R....
7页
查看更多>>摘要：In this computational work applicability of IR spectral parameters for evaluations of OH center dot center dot center dot N hydrogen bond length is discussed. For a set of 124 complexes with OH center dot center dot center dot N hydrogen bond formed by combinations of methanol/acetic acid and pyridine (and their fluorine substituted versions) geometries, energies and IR parameters were calculated at MP2/def2-TZVP level of theory. For a number of IR parameters (the shift of proton donor group stretching vibration Delta nu(s), increase of its intensity I, the low-frequency hydrogen bond stretching vibration nu(sigma), bending in-plane delta and out-of-plane gamma vibrations) equations linking them with interatomic distances are proposed, the robustness and accuracy of such equations are discussed. The enthalpy of OH center dot center dot center dot N hydrogen bond formation Delta H was also linked with electron density parameters in (3; -1) critical point. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Graphene quantum dots have been widely applied in biosensing, fluorescence imaging, biomedicine, energy storage and conversion and catalysis, but design and synthesis of polychromatic graphene quantum dot with high luminous efficiency still faces great challenges. The study reports synthesis of histidine, serine and pentaethylenehexamine-functionalized and boron-doped graphene quantum dot (HSPB-GQD) via one-step pyrolysis. The resulting HSPB-GQD consists of graphene sheets of 2-5 nm with carboxyl, hydroxyl, amino, imino and imidazole. Synergy of histidine, serine, pentaethylenehexamine and boron atoms improves the luminescence behavior. This realizes unique switchable two-color luminescence. UV excitation of 370 nm produces one strong blue fluorescence with the maximum emission wavelength of 455 nm and quantum yield of 72.34%. Vis. excitation of 480 nm produces one strong yellow fluorescence with the maximum emission wavelength of 560 nm and quantum yield of 72.59%. The multiple proton dissociation system constructed by nitrogen-containing and oxygen-containing groups makes yellow fluorescence sensitive to environmental pH value. The intensity linearly increases with increasing pH in the range of 4.5-10.0. Organic molecules and inorganic ions do not interfere pH detection. HSPB-GQD as a promising fluorescence probe with negligible effect on cell viability was successfully applied to pH detection in biological and environmental water samples and cell imaging. (C) 2022 Published by Elsevier B.V.
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