March 2025
·
1 Read
Talanta
What is this page?
This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.
Publications (2)
![a) Absorption spectra and b) absorbance versus time representations (λmax), obtained during the enzymatic reaction of tyramine (10⁻⁴M) in phosphate buffer pH = 7: green line indicates the following: AuNP ([Au(III)] = 1 mM, [TAO] = 0.5 U/mL, 40 °C, 0.1M buffer). Blue line indicates the following: AuPdNP ([Au(III)] = 0.5 mM, [Pd(II)] = 1.5 mM, [TAO] = 0.25 U/mL, 40 °C, 0.3M buffer). Red line indicates the following: AuPtNP ([Au(III)] = 0.5 mM, [Pt(II)] = 1.0 mM, [TAO] = 0.125 U/mL, 25°C, 0.1M buffer)](https://www.researchgate.net/publication/369034975/figure/fig1/AS:11431281142435974@1681178146639/a-Absorption-spectra-and-b-absorbance-versus-time-representations-lmax-obtained_Q320.jpg)
![Schematic representation of the a) direct and b) inverse method, and the final molecular absorption spectra obtained in each case. Experimental conditions for the direct method as indicated in Fig. 1; for the inverse method ([Au(III)] = 0.5 mM, [Pt(II)] = 0.5mM, [TAO] = 0.50 U/mL, 40 °C, 0.1M phosphate buffer pH = 7)](https://www.researchgate.net/publication/369034975/figure/fig2/AS:11431281142473396@1681178147207/Schematic-representation-of-the-a-direct-and-b-inverse-method-and-the-final-molecular_Q320.jpg)
![Inverse method: variation of the absorbance at λ = 540 nm with the reaction time for different concentrations of tyramine. [Au (III)] = 0.5 mM; [Pt (II)] = 0.5 mM; [TAO] = 0.5 U/mL; phosphate buffer 0.1 M pH 7; 40 °C](https://www.researchgate.net/publication/369034975/figure/fig3/AS:11431281142595084@1681178147624/Inverse-method-variation-of-the-absorbance-atl540-nm-with-the-reaction-time-for_Q320.jpg)
![Direct method: Abs = f(t) representations at λ = 580 nm for different concentrations of tyramine (M). [TAO] = 0.125 U/mL; [Au (III)] = 0.5 mM; [Pt (II)] = 1 mM; phosphate buffer 0.1 M pH 7; 25 °C. a blank; b 2.5 × 10⁻⁶M; c 5.0 × 10⁻⁶M; d 7.5 × 10⁻⁶M; e 1.0 × 10⁻⁵M; f 1.5 × 10⁻⁵M; g 2.5 × 10⁻⁵M; h 5.0 × 10⁻⁵M; i 1.0 × 10⁻⁴M; j 2.5 × 10⁻⁴M](https://www.researchgate.net/publication/369034975/figure/fig4/AS:11431281142595085@1681178148099/Direct-method-Absft-representations-at-l580-nm-for-different-concentrations-of_Q320.jpg)
March 2023
·
24 Reads
·
5 Citations
Microchimica Acta
In situ enzymatic generation of bimetallic nanoparticles, mainly Au/Pt, overcomes the drawbacks (continuous absorbance drift, modest LOQ, and long-time reaction) observed when AuNP alone are produced. In this study, Au/Pt nanoparticles have been characterized by EDS, XPS, and HRTEM images using the enzymatic determination of tyramine with tyramine oxidase (TAO) as a model. Under experimental conditions, the Au/Pt NPs show an absorption maximum at 580 nm which can be related to the concentration of tyramine in the range 1.0 × 10⁻⁶M to 2.5 × 10⁻⁴M with a RSD of 3.4% (n = 5, using 5 × 10⁻⁶M tyramine). The Au/Pt system enables low LOQ (1.0 × 10⁻⁶ M), high reduction of the absorbance drift, and a significant shortening of the reaction time (i.e., from 30 to 2 min for a [tyramine] = 1 × 10⁻⁴M); additionally, a better selectivity is also obtained. The method has been applied to tyramine determination in cured cheese and no significant differences were obtained compared to a reference method (HRP:TMB). The effect of Pt(II) seems to involve the previous reduction of Au(III) to Au(I) and NP generation from this oxidation state. Finally, a three-step (nucleation-growth-aggregation) kinetic model for the generation of NPs is proposed; this has enabled us to obtain a mathematical equation which explains the experimentally observed variation of the absorbance with time. Graphical abstract
Citations (1)
... It is based on the in situ generation of metallic nanomaterials during NADPH-dependent enzymatic reactions. Previous work of the research group has shown that oxidase-type enzymes are able to reduce the metallic ion to stable nanomaterials whose optical properties (absorption, fluorescence] can be related to the concentration of the corresponding analyte [24,25]. ...
- Citing Article
- Full-text available
March 2023
Microchimica Acta