RESUMEN
With due attention to adsorption of proteins on the nanoparticles surface and the formation of nanoparticle-protein corona, investigation of nanoparticles toxicity on the structure of proteins is important. Therefore, this work was done to evaluate toxicity of Zinc oxide nanoparticles (ZnO NPs) on the structure of human serum albumin (HSA) through in vitro and in silico studies. First, ZnO NPs were synthesized using hydrothermal method and their size and morphology were determined by SEM and TEM methods and then to study its toxicity on the HSA structure were used UV-Vis and fluorescence spectroscopy. Also, in order to investigate interaction mechanism of ZnO NP with HSA at the atomistic level was used molecular dynamics (MD) simulation. The obtained images from SEM and TEM showed that ZnO NPs were nanosheet with size of less than 40 nm. The results of spectroscopic studies showed ZnO NPs lead to significant conformational changes in the protein's absorption and emission spectra. Moreover, MD results indicated the minor structure changes in HSA due to interaction with ZnO NP during the 100 ns simulation, and the formation of nanoparticle-protein corona complex is mainly because of electrostatic interactions between charge groups of HSA and ZnO NP.Communicated by Ramaswamy H. Sarma.
Asunto(s)
Nanopartículas del Metal , Nanopartículas , Óxido de Zinc , Simulación por Computador , Humanos , Nanopartículas del Metal/toxicidad , Albúmina Sérica Humana , Espectrometría de Fluorescencia , Óxido de Zinc/toxicidadRESUMEN
The present work reports the adsorption of serine in the neutral and zwitterionic forms on the pure and Pt-decorated B12N12 fullerenes by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The binding energy of serine over the fullerene has been studied through its hydroxyl (-OH), carboxyl (-COOH), and amine (-NH2) functional groups. Based on our analysis, the binding energy of serine in zwitterionic form (F: -1.52â¯eV) on B12N12 fullerene is less stable than that of the neutral form (C: -1.61â¯eV) using the M06-2X functional. Our results indicated that the most stable chemisorption state for serine is through its amine group (I: -2.49â¯eV) interacting with the Pt-decorated B12N12 fullerene in comparison with the carbonyl group (J: -1.92â¯eV). The conductivity of the B12N12 and Pt-decorated B12N12 fullerenes is influenced by the energy band gap variation when serine is adsorbed upon the outer surface of fullerenes. Understanding the adsorption of serine on B12N12 and Pt-decorated B12N12 fullerenes provide fundamental knowledge for future applications in biomolecules and metal surfaces.
Asunto(s)
Fulerenos/química , Nanopartículas/química , Platino (Metal)/química , Serina/química , Adsorción , Electrones , Conformación Molecular , Fenómenos Ópticos , Espectrofotometría Infrarroja , Electricidad Estática , TermodinámicaRESUMEN
We investigated the structural, electronic, and magnetic properties of small Co(n) clusters (n = 2-6) when they were endohedrally doped into Si30C30 nanocages using ab initio calculations based on density functional theory. Two different spin-polarized functionals based on the generalized gradient and local density approximations were used to characterize Co(n)@Si30C30. It was found that the Co(n) clusters encapsulated inside Si30C30 nanocages can form stable structures due to their significant binding energies. Among the various encapsulated clusters studied, the Co4 cluster was the most stable in a Si30C30 nanocage. We also found that the magnetic moments of the clusters decreased during the encapsulation process due to substantial hybridization between the cobalt cluster and the Si30C30 nanocage structure, although the encaged Co2 cluster presented somewhat different behavior. It was found that significant magnetic moments are induced in the wall of the nanocage, and that Co(n)@Si30C30 presents higher total magnetic moments than Co(n)@C60.
Asunto(s)
Compuestos Inorgánicos de Carbono/química , Cobalto/química , Nanopartículas del Metal/química , Modelos Moleculares , Compuestos de Silicona/química , Fenómenos Electromagnéticos , Estructura Molecular , Termodinámica , VibraciónRESUMEN
A study of the electronic and optical properties of the hydrogen-terminated GaAs nanocrystals Ga68As68H96 and Ga92As80H108 is presented. In this study, their dielectric functions, refractive indices, and absorption coefficients were calculated using density functional theory (DFT). The influence of a uniform external electric field on the optical properties of the nanocrystals was also explored. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) for each nanocrystal were studied in the absence and the presence of the uniform external electric field. Our results indicate that the HOMO-LUMO gap decreases with increasing electric field strength. The calculated density of states revealed that the main reason for this shrinking gap is an increase in the delocalization of the gallium π-orbitals under the influence of an increasing external electric field. The permanent dipole moment and the polarizability of the nanocrystals under the induced electric field increased with increasing nanocrystal radius. The induced electric field caused a noticeable redshift in the absorption peaks. The electric field also increased the absorption intensity, particularly when the field strength was >0.25 V/Å.