Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles

In this paper we present a rapid and simple onepot method to obtain gold nanoparticles functionalized with folic acid using a photochemistry method. The bioconjugate folic acid-gold nanoparticle was generated in one step using a photo-reduction method, mixing hydrogen tetrachloroaurate with folic acid in different ratios and varying the illumination time of a mercury lamp (λ= 255 nm). Scanning electron microscopy showed a particle size of around 40-50nm and dynamic light scattering exhibited that the zeta potential varies from -41 to -50mV with different illumination times. Storage in the dark at 4°C prolongs the stability of folic acid-gold nanoparticle suspensions to up to 26 days. Ultraviolet visible and Fourier transform infrared spectroscopy showed a surface plasmon band of around 534nm and fluorescence spectroscopy exhibited a quenching effect on gold nanoparticles in the fluorescence emission of folic acid and thus confirmed the conjugation of folic acid to the surface of gold nanoparticles. In this study we demonstrate the use of a photochemistry method to obtain folic acid-gold nanoparticles in a simple and rapid way without the use of surfactants and long reaction times. The photochemical synthesis of FA-AuNPs opens new perspectives for creating novel functional nanomaterials for biomedical applications

Formación de O2•- y •OH en suspensiones acuosas de porfirina de Cu(II) adsorbida al TiO2 bajo radiación visible

En este trabajo, se estudió la actividad fotocatalítica inducida con luz visible de la tetra(4-carboxifenil) porfirina de Cu(II) adsorbida en la superficie de TiO2 (TcPPCu/ TiO2) en solución acuosa y en presencia de O2, mediante la degradación de dos moléculas prueba: el luminol y el ácido tereftálico. Los resultados muestran que los aniones radicales superóxido (O2•-) son las especies principalmente generadas. Sin embargo, estas especies son reductoras, por tanto, no son eficientes los sistemas empleados en la oxidación de moléculas orgánicas. En términos ambientales, es de gran interés generar especies altamente reactivas con luz visible, puesto que el 95% de la radiación solar que alcanza la superficie terrestre corresponde a la región visible. La generación de especies más reactivas que O2•-, como los radicales hidroxilo (•OH), con radiación visible no es proceso fácil. Sin embargo, al lograrlo, resulta en un proceso ambientalmente amigable y de bajo costo. Con el objeto de generar radicales hidroxilo (•OH), con luz visible, en este trabajo, se empleó H2O2. La producción de •OH se indujo a de la reducción de H2O2 con O2•- o por los electrones que se transfieren a la banda de conducción del TiO2, desde un estado excitado de la porfirina. Así, el sistema TcPPCu/TiO2, O2, H2O2 puede considerarse como una nueva alternativa, ecológica, en el tratamiento de aguas residuales

Review of the synthesis of layered double hydroxides: a thermodynamic approach

The synthesis of layered double hydroxides (LDHs) by hydrothermal-LDH reconstruction and coprecipitation methods is reviewed using a thermodynamic approach. A mixture model was used for the estimation of the thermodynamics of formation of LDHs. The synthesis and solubility of LDHs are discussed in terms of standard molar Gibbs free energy change of reaction. Data for numerous divalent and trivalent metals as well as for some monovalent and tetravalent metals that may be part of the LDH structure have been compiled. Good agreement is found between theoretical and experimental data. Diagrams and tables for the prediction of possible new LDH materials are provided

Models for the estimation of thermodynamic properties of layered double hydroxides: application to the study of their anion exchange characteristics

Several models for the estimation of thermodynamic properties of layered double hydroxides (LDHs) are presented. The predicted thermodynamic quantities calculated by the proposed models agree with experimental thermodynamic data. A thermodynamic study of the anion exchange process on LDHs is also made using the described models. Tables for the prediction of monovalent anion exchange selectivities on LDHs are provided. Reasonable agreement is found between the predicted and the experimental monovalent anion exchange selectivities