Person:
Gómez Gómez, Beatriz

Profile Picture
First Name
Beatriz
Last Name
Gómez Gómez
URI
https://hdl.handle.net/20.500.14352/82513
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Department
Area
Identifiers
UCM identifierORCIDScopus Author IDDialnet ID

Filters

2022 - 20232
Reset filters

Settings

Author: León González, María Eugenia De × Subject: 543 ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Characterization of AgNPs and AuNPs in sewage sludge by single particle inductively coupled plasma-mass spectrometry
    (Talanta, 2022) Moreno Martín, Gustavo; Gómez Gómez, Beatriz; León González, María Eugenia De; Madrid Albarrán, María Yolanda; Elsevier
    This study develops for the first time an analytical method for the characterization of silver and gold nanoparticles in sewage sludge. The evaluation of the effect of temperature, extracting agent and centrifugation speed and time on the extraction yield was carried out through a multifactorial analysis of variance which allows us to select 289 g, 5 min and 20 mM sodium pyrophosphate tetrabasic as optimal extraction conditions. Under these conditions, the analysis of the extract by single particle inductively coupled plasma-mass spectrometry provided recovery percentages of 70 ± 2% and 56 ± 1% for silver and gold nanoparticles, respectively. Moreover, the complementary results obtained upon analysis of these extracts by transmission electron microscopy and single particle inductively coupled plasma-mass spectrometry showed that the developed method did not modify the original size and shape of these nanoparticles during the extraction procedure. Size detection limits of 23 nm and 16 nm as well as number concentration limits of 3.12 × 109 particles kg−1 and 1.38 × 109 particles kg−1 were obtained for silver and gold nanoparticles, respectively. Moreover, a stability study of silver and gold nanoparticles in sewage sludge for 12 months showed differences between the two nanoparticle types. Although the sizes were not affected during the 12 months, silver nanoparticles underwent an oxidation process from 6 months onwards, which was reflected in an increase in the percentage of ionic silver from 14 ± 1% at 6 months to 24 ± 2% at 12 months. The developed methodology represents a simple, reliable and fast tool for detecting, quantifying and assessing the stability of nanoparticles in an important environmental sample such as sewage sludge.
  • Thumbnail Image
    Item
    Evaluation of the transformation of selenite and selenium nanoparticles to seleno-amino acids produced by Escherichia coli and Staphylococcus aureus by using liquid chromatography -inductively coupled plasma mass spectrometry and single-particle- inductively coupled plasma mass spectrometry and different sample treatments
    (Spectrochimica Acta Part B: Atomic Spectroscopy, 2023) Moreno Martín, Gustavo; Espada-Bernabé, Elena; Gómez Gómez, Beatriz; León González, María Eugenia De; Madrid Albarrán, María Yolanda
    Due to the scarce knowledge about the impact of selenium nanoparticles (SeNPs) on bacterial populations, the main objective of this work was focused on evaluating the transformations of SeNPs and selenite in Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). For this purpose, an analytical methodology based on bacteria cell wall disruption, carbamidomethylation, enzymatic hydrolysis and high-performance liquid chromatography couple to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and HPLC- electrospray tandem mass spectrometry (HPLC-ESI-MS/MS) measurements was developed, the latter for unambiguous identification of selenium species. Once bacteria were cultured in the presence of chitosan modified SeNPs (Ch-SeNPs) and selenite at 0, 1 and 2 mg L􀀀 1 Se for 24 h, an enzymatic disruption of the bacterial cell wall using lysozym followed by enzymatic hydrolysis with protease was applied. The use of lysozyme to extract selenium speciesprovided a better efficiency in the total selenium content (higher than 96%), compared to a mechanical disruption of the bacterial cell wall. Analysis of the extracts by anionic exchange HPLC-ICP-MS showed a strong influence of incubation time with protease (24, 48 and 72 h) on selenium chromatographic profile. The results showed that selenocysteine (SeCys) was the only Se species identified in both bacteria representing an 80% of total selenium accumulated. The confirmation of the identity of this Se species was carried out after performing a carbamidomethylation process, prior to enzymatic hydrolysis, and analyzing the extract by reversed phase HPLCESI- MS/MS. These analyses confirmed the presence of SeCys, and no relevant differences were found between the metabolic pathway of both forms of selenium. Moreover, the growth of both bacterial species in the presence of selenite resulted in the formation of biogenic SeNPs. Characterization by TEM before and after their separation from the culture medium showed spherical and monodispersed nanoparticles with an average size (155 ± 19) nm and (172 ± 20) nm for E. coli and S. aureus, respectively. Analysis by spICP-MS showed no significant differences in size with respect to TEM after considering the ionization efficiency of Se.