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Office paper platform for bioelectrochromic detection of electrochemically active bacteria using tungsten trioxide nanoprobes.

Marques AC, Santos L, Costa MN, Dantas JM, Duarte P, Gonçalves A, Martins R, Salgueiro CA, Fortunato E - Sci Rep (2015)

Bottom Line: This allowed the production of a paper-based colorimetric sensor able to detect EAB in a simple, rapid, reliable, inexpensive and eco-friendly method.The developed platform was then tested with Geobacter sulfurreducens, as a proof of concept.G. sulfurreducens cells were detected at latent phase with an RGB ratio of 1.10 ± 0.04, and a response time of two hours.

View Article: PubMed Central - PubMed

Affiliation: 1] Departamento de Ciência dos Materiais, CENIMAT/I3N and CEMOP/UNINOVA, Faculdade de Ciências e Tecnologia - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal [2] Departamento de Química, UCIBIO-REQUIMTE, Faculdade de Ciências e Tecnologia - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.

ABSTRACT
Electrochemically active bacteria (EAB) have the capability to transfer electrons to cell exterior, a feature that is currently explored for important applications in bioremediation and biotechnology fields. However, the number of isolated and characterized EAB species is still very limited regarding their abundance in nature. Colorimetric detection has emerged recently as an attractive mean for fast identification and characterization of analytes based on the use of electrochromic materials. In this work, WO3 nanoparticles were synthesized by microwave assisted hydrothermal synthesis and used to impregnate non-treated regular office paper substrates. This allowed the production of a paper-based colorimetric sensor able to detect EAB in a simple, rapid, reliable, inexpensive and eco-friendly method. The developed platform was then tested with Geobacter sulfurreducens, as a proof of concept. G. sulfurreducens cells were detected at latent phase with an RGB ratio of 1.10 ± 0.04, and a response time of two hours.

No MeSH data available.


XRD diffractograms of the WO3 nanoparticles.(A) WO3 nanoparticles synthesized from Na2WO4·2H2O, NaCl solutions; (B) WO3 nanoparticles synthesized from Na2WO4·2H2O, Na2SO4 solutions; (C) WO3 nanoparticles synthesized from PTA solutions. The peaks marked as * and ♦ are characteristic of Na2WO4·2H2O and H2WO4 structures. The peaks marked as Δ are non-identified. The crystalline structures were produced with the CrystalMaker software (Centre for Innovation & Enterprise, Oxford).
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f1: XRD diffractograms of the WO3 nanoparticles.(A) WO3 nanoparticles synthesized from Na2WO4·2H2O, NaCl solutions; (B) WO3 nanoparticles synthesized from Na2WO4·2H2O, Na2SO4 solutions; (C) WO3 nanoparticles synthesized from PTA solutions. The peaks marked as * and ♦ are characteristic of Na2WO4·2H2O and H2WO4 structures. The peaks marked as Δ are non-identified. The crystalline structures were produced with the CrystalMaker software (Centre for Innovation & Enterprise, Oxford).

Mentions: The crystallographic structure of the synthesized WO3 nanoparticles was determined by X-ray diffraction (XRD) (Figure 1) and corroborated by Fourier transform infrared spectroscopy (FT-IR) (Fig. S1). Tungsten oxides follow a well-known ReO3-type structure built up of layers containing distorted corner-shared WO6 octahedra. The growing process of WO3 nanostructures can be described in three major steps: (i) formation of the tungstic acid (H2WO4), (ii) formation of WO3 clusters by decomposition of H2WO4 and (iii) growth of WO3 crystal nucleus29. In the synthesis with sodium tungstate dihydrate (Na2WO4·2H2O) as precursor and NaCl as structure-directing agent (SDA) (Figure 1A), WO3 nanoparticles grow in a monoclinic (m-WO3) crystallographic structure (ICDD #00-043-1035) at pH 0.0 and orthorhombic (o-WO3·0.33H2O) (ICDD #01-072-0199) at pH 1.8. At pH 0.4 the WO3 nanoparticles are a mixture of the two phases, monoclinic and orthorhombic, together with the precursor (marked with *) and tungstic acid (marked with ♦). Using Na2SO4 as SDA (Figure 1B), orthorhombic and hexagonal (h-WO3) (ICDD #01-075-2187) phases were obtained at pH 0.4 and pH 1.8, respectively. At pH 0.4 the sample also shows a peak assigned to the acid tungstic (♦) and two unidentified peaks (Δ) that are due to lattice distortions of the crystallographic structure, as previously reported for WO3 nanoparticles prepared by hydrothermal synthesis30. Finally, using peroxopolytungstic acid (PTA) as precursor (Figure 1C), the crystallographic structure of the synthesized nanopowder is monoclinic for the lowest and higher pH values, which is in agreement with previous reports, although with different crystallographic plane intensities29. For the intermediate pH value, the WO3 nanoparticles present an orthorhombic phase. The FT-IR analysis is in accordance with the crystallographic structures attributed by XRD. However, the samples prepared with PTA precursor also revealed the presence of a W = O vibration bond that are assigned to some impurities. In general, the formation of nanoparticles is favourable for pH values lower that 2.0, however at pH 0.4 tend to form bundle structures and a mixture of phases and/or impurities31.


Office paper platform for bioelectrochromic detection of electrochemically active bacteria using tungsten trioxide nanoprobes.

Marques AC, Santos L, Costa MN, Dantas JM, Duarte P, Gonçalves A, Martins R, Salgueiro CA, Fortunato E - Sci Rep (2015)

XRD diffractograms of the WO3 nanoparticles.(A) WO3 nanoparticles synthesized from Na2WO4·2H2O, NaCl solutions; (B) WO3 nanoparticles synthesized from Na2WO4·2H2O, Na2SO4 solutions; (C) WO3 nanoparticles synthesized from PTA solutions. The peaks marked as * and ♦ are characteristic of Na2WO4·2H2O and H2WO4 structures. The peaks marked as Δ are non-identified. The crystalline structures were produced with the CrystalMaker software (Centre for Innovation & Enterprise, Oxford).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4402613&req=5

f1: XRD diffractograms of the WO3 nanoparticles.(A) WO3 nanoparticles synthesized from Na2WO4·2H2O, NaCl solutions; (B) WO3 nanoparticles synthesized from Na2WO4·2H2O, Na2SO4 solutions; (C) WO3 nanoparticles synthesized from PTA solutions. The peaks marked as * and ♦ are characteristic of Na2WO4·2H2O and H2WO4 structures. The peaks marked as Δ are non-identified. The crystalline structures were produced with the CrystalMaker software (Centre for Innovation & Enterprise, Oxford).
Mentions: The crystallographic structure of the synthesized WO3 nanoparticles was determined by X-ray diffraction (XRD) (Figure 1) and corroborated by Fourier transform infrared spectroscopy (FT-IR) (Fig. S1). Tungsten oxides follow a well-known ReO3-type structure built up of layers containing distorted corner-shared WO6 octahedra. The growing process of WO3 nanostructures can be described in three major steps: (i) formation of the tungstic acid (H2WO4), (ii) formation of WO3 clusters by decomposition of H2WO4 and (iii) growth of WO3 crystal nucleus29. In the synthesis with sodium tungstate dihydrate (Na2WO4·2H2O) as precursor and NaCl as structure-directing agent (SDA) (Figure 1A), WO3 nanoparticles grow in a monoclinic (m-WO3) crystallographic structure (ICDD #00-043-1035) at pH 0.0 and orthorhombic (o-WO3·0.33H2O) (ICDD #01-072-0199) at pH 1.8. At pH 0.4 the WO3 nanoparticles are a mixture of the two phases, monoclinic and orthorhombic, together with the precursor (marked with *) and tungstic acid (marked with ♦). Using Na2SO4 as SDA (Figure 1B), orthorhombic and hexagonal (h-WO3) (ICDD #01-075-2187) phases were obtained at pH 0.4 and pH 1.8, respectively. At pH 0.4 the sample also shows a peak assigned to the acid tungstic (♦) and two unidentified peaks (Δ) that are due to lattice distortions of the crystallographic structure, as previously reported for WO3 nanoparticles prepared by hydrothermal synthesis30. Finally, using peroxopolytungstic acid (PTA) as precursor (Figure 1C), the crystallographic structure of the synthesized nanopowder is monoclinic for the lowest and higher pH values, which is in agreement with previous reports, although with different crystallographic plane intensities29. For the intermediate pH value, the WO3 nanoparticles present an orthorhombic phase. The FT-IR analysis is in accordance with the crystallographic structures attributed by XRD. However, the samples prepared with PTA precursor also revealed the presence of a W = O vibration bond that are assigned to some impurities. In general, the formation of nanoparticles is favourable for pH values lower that 2.0, however at pH 0.4 tend to form bundle structures and a mixture of phases and/or impurities31.

Bottom Line: This allowed the production of a paper-based colorimetric sensor able to detect EAB in a simple, rapid, reliable, inexpensive and eco-friendly method.The developed platform was then tested with Geobacter sulfurreducens, as a proof of concept.G. sulfurreducens cells were detected at latent phase with an RGB ratio of 1.10 ± 0.04, and a response time of two hours.

View Article: PubMed Central - PubMed

Affiliation: 1] Departamento de Ciência dos Materiais, CENIMAT/I3N and CEMOP/UNINOVA, Faculdade de Ciências e Tecnologia - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal [2] Departamento de Química, UCIBIO-REQUIMTE, Faculdade de Ciências e Tecnologia - Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.

ABSTRACT
Electrochemically active bacteria (EAB) have the capability to transfer electrons to cell exterior, a feature that is currently explored for important applications in bioremediation and biotechnology fields. However, the number of isolated and characterized EAB species is still very limited regarding their abundance in nature. Colorimetric detection has emerged recently as an attractive mean for fast identification and characterization of analytes based on the use of electrochromic materials. In this work, WO3 nanoparticles were synthesized by microwave assisted hydrothermal synthesis and used to impregnate non-treated regular office paper substrates. This allowed the production of a paper-based colorimetric sensor able to detect EAB in a simple, rapid, reliable, inexpensive and eco-friendly method. The developed platform was then tested with Geobacter sulfurreducens, as a proof of concept. G. sulfurreducens cells were detected at latent phase with an RGB ratio of 1.10 ± 0.04, and a response time of two hours.

No MeSH data available.