Juan J. Delgado-Jaén’s research while affiliated with Universidad de Cádiz and other places

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Publications (2)


Biosynthesis of uniform ultra-small gold nanoparticles by aged Dracaena Draco L extracts
  • Article

August 2019

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59 Reads

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14 Citations

Colloids and Surfaces A Physicochemical and Engineering Aspects

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The biosynthesis of ultra-small gold nanoparticles (AuNPs) with very narrow size distribution and stable dispersion through an aqueous drago (Dracaena draco L) aged leaf extract used as a non-toxic reducing and stabilizing agent has been achieved. The gold nanoparticles obtained in this way, have a size in the range 0.9–2.8 nm and an average size of 1.63 ± 0.35 nm. The ageing of the extract was fundamental to the success of the synthesis as it reduced the size of the nanoparticles by half and improved their stability. This natural ageing process, which to the best of our knowledge is described for the first time in biosynthesis, was accomplished by incubating the extract at ambient temperature without incorporating chemicals during 14 days. The optimized synthesis process took only 15 min at 60 °C. The morphology and crystalline phase of the AuNPs were characterized by transmission electron microscopy. The composition of the nanoparticles was evaluated by electron diffraction and X-ray energy dispersive spectroscopy. The stability of the AuNPs was estimated by a combination of dynamic light scattering and UV–vis spectroscopy. Fourier transform infrared spectroscopy (FTIR) and total phenolic content data, evidenced the evolution of the extract during the ageing process and the presence of biomolecules that could be responsible for reducing Au³⁺ and capping the AuNPs. A mechanism for the formation of the AuNPs and a hypothesis concerning the types of organic molecules involved in this process are also proposed.


Physicochemical properties of nanostructured Pd/lanthanide doped ceria spheres with high catalytic activity for CH4 combustion

March 2018

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41 Reads

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14 Citations

Journal of Materials Chemistry A

In this work, nanostructured Ce0.9Gd0.1O2- (GDC) and Ce0.9Pr0.1O2- (PrDC) spheres previously obtained by microwave assisted hydrothermal homogeneous co-precipitation were impregnated with 1 wt% Pd by the incipient wetness impregnation of an aqueous Pd2+ solution. Their properties were characterized by synchrotron radiation X-ray diffraction (SR-XRD), X-ray absorption near-edge spectroscopy (XANES) and scanning and high resolution electron microscopy with Xray spectroscopy. Spherical particles with average diameters around 200 nm were found to consist of crystallites of average size, 10 nm, with small particles of PdO finely dispersed over the sphere surface. In situ XRD and XANES experiments were carried out under reducing and oxidizing conditions in order to investigate the redox behaviour of these materials and to evaluate the effect of Pd loading on the oxidation state of Ce. All of the lanthanide-doped ceria (LnDC) supports were found to have a cubic crystal structure (Fm3m space group). An increase in lattice parameters was observed under reducing conditions which was attributed to the reduction of Ce4+ ions to the larger Ce3+ ions, and to the associated increase in oxygen vacancy (VO) concentration. Addition of Pd to the LnDC spheres increased their Ce3+ content. Finally, catalytic tests for CH4 combustion were performed on the LnDC and Pd/LnDC nanocatalysts. The best performance was observed in samples with 1 wt% Pd loading, which exhibited T50 values (temperature at which 50% of CH4 conversion was reached) close to 310 oC. These values are 220 oC and 260 oC lower than those obtained for nanostructured PrDC and GDC spheres alone, respectively.

Citations (2)


... Using dendritic-Fe 3 O 4 nanomaterials, the researchers achieved healthy renal function in the mice. This confirms that IO@PAMAM and IO@KR 2 nanomaterials are biocompatible [46][47][48]. ...

Reference:

Synergic Fabrication of Cabazitaxel-Loaded Dendritic Supramolecular Iron Nanomaterials for the Delivery of Tumor Regression and Magnetic Drug Targeting (MDT) in the Melanoma Tumor Model
Biosynthesis of uniform ultra-small gold nanoparticles by aged Dracaena Draco L extracts
  • Citing Article
  • August 2019

Colloids and Surfaces A Physicochemical and Engineering Aspects

... The catalyst morphology was first studied through field emission scanning electron microscopy (FESEM) and the obtained images are reported in Figure 2 and 3. Figure 2a and Figure 2b show the FESEM micrographs of Pd/CeO 2 _S and Pd/ Ce90Pr10_S materials obtained without template reproducing the synthesis procedure described in. [29] However, as opposed to what is described in the reference paper, uniform spherical particles with a confined distribution were not present in the samples of this work. Indeed, larger spheres (1-3 μm) covered by smaller spherical particles (100-300 nm) were noticed (as shown in the lower-magnification image in Figure 3a). ...

Physicochemical properties of nanostructured Pd/lanthanide doped ceria spheres with high catalytic activity for CH4 combustion
  • Citing Article
  • March 2018

Journal of Materials Chemistry A