Domitille Giaume - Academia.edu (original) (raw)

Papers by Domitille Giaume

Nano Letters, 2004

Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological la... more Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological labels. These nanoparticles are synthesized directly in water, which facilitates their functionalization, and are remarkably photostable without emission intermittency. Nanoparticles functionalized with guanidinium groups act as artificial toxins and specifically target sodium channels. They are individually detectable in live cardiac myocytes, revealing a heterogeneous distribution of sodium channels. Functionalized oxide nanoparticles appear to be a novel tool that is particularly attractive for long-term single-molecule tracking.

Meeting Abstracts, Jun 4, 2012

#582, Honolulu PRiME 2012, © 2012 The Electrochemical Society ) unless CC License in place (see a... more #582, Honolulu PRiME 2012, © 2012 The Electrochemical Society ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 54.160.112.150 Downloaded on 2017-03-26 to IP

Journal of Luminescence, 2015

The Journal of Physical Chemistry C, 2015

ABSTRACT The broadband dielectric spectroscopy has been applied, for the first time, to nanoplate... more ABSTRACT The broadband dielectric spectroscopy has been applied, for the first time, to nanoplatelets of NaxCoO2. yH2O. Permittivity and conductivity have been measured on a wide frequency range from a few Hz to microwaves. The effect of hydration state on the electrical transport and ageing (drying and rehydration cycles) on the electrical properties of the NaxCoO2 nanoplatelets is well evidenced. While the sample dehydrated under vacuum (NaxCoO2.0.25 H2O) shows a metallic behavior, it becomes a semiconductor with a thermally activated conduction upon rehydration (NaxCoO2,0.5 H2O). The fully hydrated material (NaxCoO2.0.7 H2O) obtained after synthesis and mild drying at 293 K evidences two sharp and intense conductivity and permittivity resonances above room temperature in the microwave region. We associate these two resonances to Charge Density Waves coupling electronic transport and ionic polarizations associated to the presence of structural water in the NaxCoO2 interlayers.

MRS Proceedings, 2013

Development of devices storing and delivering high-energy power such as supercapacitors is necess... more Development of devices storing and delivering high-energy power such as supercapacitors is necessary to assist intermittent sources of energy. Most of the commercial systems are carbon-based, but due to their high surface charge, oxides offer a valuable alternative for high-rate energy storage. Among them, layered transition metal oxides with mixed valence properties present both good electronic and ionic conductivities suitable for application to electrochemical applications intermediate between capacitors and batteries. This work focuses on lamellar oxide bronzes based on cobalt M x CoO 2 and vanadium M x V 2 O 5 (M = H, Li, Na or K). A low temperature synthesis leads to high specific area particles (above 100 m 2 /g). Hydrated and anhydrous Na x CoO 2 are promising cathode materials for aqueous supercapacitors, with a high capacity of more than 100 mAh/g obtained under 20 mV/s for the hydrated Na x CoO 2 . The M x V 2 O 5 bronzes appear to be good candidates for organic supercapacitors, especially the Li x V 2 O 5 bronze, which shows a high stable capacity above 100 mAh/g (at 20 mV/s ie a charging time of 125 s).

Colloidal Quantum Dots for Biomedical Applications II, 2007

ABSTRACT We report on the single-particle properties of lanthanide-ion doped oxide nanoparticles.... more ABSTRACT We report on the single-particle properties of lanthanide-ion doped oxide nanoparticles. We have demonstrated that their size can be accurately determined from their luminosity. The optically determined size distribution is in very good agreement with the distribution obtained from transmission electron microscopy (TEM). We also showed that the photobleaching of these nanoparticles is related to a reduction process and that we can use it to sense in a concentration-dependent manner the presence of an oxidant like H2O2. Finally, we propose a way to perform nanoparticle-protein coupling and to determine the protein-nanoparticle ratio at the single-particle level.

MRS Proceedings, 2004

Lanthanide-ion doped oxide (YVO 4 :Eu) nanoparticles were synthesized as aqueous colloids and fun... more Lanthanide-ion doped oxide (YVO 4 :Eu) nanoparticles were synthesized as aqueous colloids and functionalized by a bioactive silane shell to be used as fluorescent biological labels. Nanoparticles functionalized with guanidinium groups were able to act as artificial toxins which specifically target Na' channels. They were individually detectable in live cardiac myocytes. Functionalized oxide nanoparticles appear as a new interesting tool, especially attractive for long-term single-molecule tracking due to their photo-stability and long luminescence lifetime. * The composition of the physiological Ringer solution was (mM): NaCI: 1103.5; KCI: 2.5: Ca Cl,: 2; MgC : 1; Na*pyruvate: 5: HEPES (NaOH): 10; glucose: 10; alhumine: I mg/mil; pH: 7.34.

Journal of Power Sources, 2014

A moderate pressure not collapsing porosity strongly improves capacitor performance. Electronic c... more A moderate pressure not collapsing porosity strongly improves capacitor performance. Electronic conductivity of an oxide electrode limits its electrochemical properties. A moderate pressure applied on powder strongly improves grain to grain connectivity. Formulation with carbon additive is mandatory to get high electronic conductivities.

MRS Proceedings, 2007

... molecule. REFERENCES 1. J. Zhang, RE Campbell, AY Ting, RY Tsien, Nat. Rev. Mol. Cell Biol. 2... more ... molecule. REFERENCES 1. J. Zhang, RE Campbell, AY Ting, RY Tsien, Nat. Rev. Mol. Cell Biol. 2002, 3, 906 2. WCW Chan, S. Nie, Science 1998, 281, 2016 M. Bruchez, M. Moronne, P. Gin, S. Weiss, AP Alivisatos Science 1998, 281, 2013. ...

The Journal of Physical Chemistry B, 2006

We used lanthanide-ion doped oxide nanoparticles, Y 0.6 Eu 0.4 VO 4 , as donors in fluorescent re... more We used lanthanide-ion doped oxide nanoparticles, Y 0.6 Eu 0.4 VO 4 , as donors in fluorescent resonance energy transfer (FRET) experiments. The choice of these nanoparticles allows us to combine the advantages of the lanthanide-ion emission, in particular the long lifetime and the large Stokes shift between absorption and emission, with the detectability of the nanoparticles at the single-particle level. Using cyanine 5 (Cy5) organic molecules as acceptors, we demonstrated FRET down to the single-nanoparticle level. We showed that, due to the long donor lifetime, unambiguous and precise FRET measurements can be performed in solution even in the presence of large free acceptor concentrations. Highly efficient energy transfer was obtained for a large number of acceptor molecules per donor nanoparticle. We determined FRET efficiencies as a function of Cy5 concentration which are in good agreement with a multiple acceptor-multiple donor calculation. On the basis of the donor emission recovery due to acceptor photobleaching, we demonstrated energy transfer from single-nanoparticle donors in fluorescence microscopy experiments.

Progress in Solid State Chemistry, 2005

Rare earth doped oxide materials are well known for their numerous applications in light emitting... more Rare earth doped oxide materials are well known for their numerous applications in light emitting devices. An interesting issue is to study the emission properties of nanoparticles, with the aim to understand the influence of small size and surface effects on the emission processes. These particles could furthermore be used in new applications such as the elaboration of transparent emitting devices or new biological labels. The work presented here concerns highly luminescent rare earth doped yttrium vanadates (YVO 4 :Eu) and lanthanum phosphate LaPO 4 :Ce,Tb$xH 2 O nanoparticles. Simple aqueous colloidal syntheses are used for the elaboration of concentrated colloids based on the progressive decomposition of polymeric precursors at moderate temperature (60e90 C). Both types of particles exhibit strong emission (quantum yields of 25% and 45% for vanadates and phosphates, respectively), but significantly lower than that for the equivalent bulk materials. The alteration of the emission processes is discussed in terms of surface quenching effects. Improvements are obtained through the elaboration of core/shell nanostructures. Surface derivatization has been achieved through the controlled growth of an organically modified silica shell using a functionalized silane precursor. Two examples are given concerning the applications of those particles. The first one is the elaboration of transparent and highly luminescent thin films, obtained by the dispersion of the functionalized particles in a solegel silica matrix. The other one is the use of Progress in Solid State Chemistry 33 www.elsevier.com/locate/pssc guanidine functionalized particles as biological labels for the single particle detection of sodium channels in cardiac cells.

Physical Review Letters, 2013

A homogeneous linewidth of 85:6 AE 4:4 kHz is reported in 60 nm Eu 3þ doped Y 2 O 3 nanocrystals ... more A homogeneous linewidth of 85:6 AE 4:4 kHz is reported in 60 nm Eu 3þ doped Y 2 O 3 nanocrystals at 1.3 K. This linewidth was measured by two-pulse photon echoes on highly scattering powders using heterodyne detection. Spectral diffusion was also investigated by three-pulse photon echoes and resulted in a limited broadening of the homogenous linewidth of about 250 kHz over 120 s. Compared to achievable Rabi frequencies, in the range of several MHz, these values show that rare earth doped nanocrystals can be useful for applications in optical quantum information processing.

Nano Letters, 2004

Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological la... more Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological labels. These nanoparticles are synthesized directly in water, which facilitates their functionalization, and are remarkably photostable without emission intermittency. Nanoparticles functionalized with guanidinium groups act as artificial toxins and specifically target sodium channels. They are individually detectable in live cardiac myocytes, revealing a heterogeneous distribution of sodium channels. Functionalized oxide nanoparticles appear to be a novel tool that is particularly attractive for long-term single-molecule tracking.

Langmuir, 2008

Luminescent inorganic nanoparticles are now widely studied for their applications as biological p... more Luminescent inorganic nanoparticles are now widely studied for their applications as biological probes for in vitro or in vivo experiments. The functionalization of the particles is a key step toward these applications, since it determines the control of the coupling between the particles and the biological species of interest. This paper is devoted to the case of rare earth doped oxide nanoparticles and their functionalization through their surface encapsulation with a functional polysiloxane shell. The first step of the process is the adsorption of silicate ions that will act as a primary layer for the further surface polymerization of the silane, either aminopropyltriethoxysilane (APTES) or glycidoxypropyltrimethoxysilane (GPTMS). The amino- or epoxy- functions born by the silane allow the versatile coupling of the particles with bio-organic species following the chemistry that is commonly used in biochips. Special attention is paid to the careful characterization of each step of the functionalization process, especially concerning the average number of organic functions that are available for the final coupling of the particles with proteins. The surface density of amino or epoxy functions was found to be 0.4 and 1.9 functions per square nanometer for GPTMS and APTES silanized particles, respectively. An example of application of the amino-functionalized particles is given for the coupling with alpha-bungarotoxins. The average number (up to 8) and the distribution of the number of proteins per particle are given, showing the potentialities of the functionalization process for the labeling of biological species.

Journal of the American Chemical Society, 2007

coprecipitation as described by Huignard et al., 2000. The obtained nanoparticles were coated by ... more coprecipitation as described by Huignard et al., 2000. The obtained nanoparticles were coated by a thin silica layer that acts as a stabilizer and a primary layer for the further aminosilane functionalization. This silica layer was obtained by the addition of tetramethylammonium silicate ((CH 3 ) 4 NOH.2SiO 2 , Aldrich) into the colloidal solution of Y 0.6 Eu 0.4 VO 4 nanoparticles in a similar way to that demonstrated by Philipse et al., 1994 and Correa-Duarte et al., 1998. We used a large excess of silicate with a concentration about ten times the total vanadate (VO 4 3-) ion concentration. The colloidal dispersion was then left under stirring overnight. It was then purified by dialysis against water for a period of about 100 h in order to remove the excess silicate ions, leaving a thin layer of adsorbed silicate ions. The final conductivity of the solution was about 100 mS·cm -2 .

Journal of Materials Chemistry, 2006

Besides well-known quantum dots, lanthanide-doped oxide nanocrystals form a new promising class o... more Besides well-known quantum dots, lanthanide-doped oxide nanocrystals form a new promising class of nanophosphors. Lanthanide vanadate and phosphate nanoparticles are prepared as welldispersed and highly concentrated colloids by a very simple aqueous route, using competition between precipitation and complexation reactions. Under UV excitation, the three basic colors are furnished by YVO 4 : Eu (red), LaPO 4 : Ce?0.7H 2 O (blue-violet) and LaPO 4 : CeTb?0.7H 2 O (green). In the case of cerium-doped phosphate nanoparticles, the epitaxial growth of a LaPO 4 ?0.7H 2 O shell leads to ''core-shell'' nanocrystals presenting improved stability against cerium oxidation which is detrimental for the luminescence. Nanocrystals exhibiting passivation and chemical or biological functionalization are easily prepared using the silane strategy. The optimized nanophosphors are either dispersed in transparent sol-gel films or used as isolated particles for biological labelling. The luminescence properties of nanoparticles differ from corresponding bulk materials in several ways : (i) spectroscopic changes, as a systematic broadening of the luminescence bands in sub-20 nm nanocrystals, resulting from a structural disorder intrinsic to the small size; (ii) a lower luminescence quantum yield related to the presence of chemical species adsorbed at the surface, especially the OH groups; (iii) a shift towards higher values of the optimum doping concentration, due to the alteration of energy transfers either in the vanadate or cerium sub-networks.

Journal of Luminescence, 2012

Transparent luminescent Y 0.98-x Bi x Eu 0.02 VO 4 (0<x<1) ceramic films have been prepared using... more Transparent luminescent Y 0.98-x Bi x Eu 0.02 VO 4 (0<x<1) ceramic films have been prepared using a polymeric route and heat-treatment at 550°C. A solid solution of zircon-type Y 1-x Bi x VO 4 is obtained for x values below 0.5 whereas phase separation is observed above this limit. The absorption spectra of the films show a shift of the band edge towards high wavelength with the bismuth content, as theoretical calculi have predicted. Luminescence of the films under a UV excitation is typical of europium ion in the zircon structure. The poor correlation between absorption and excitation spectra at high bismuth content is coherent with desexcitation in localized states of valence band. However, the excitation wavelength could still be tuned from deep-UV to near-UV range by inserting bismuth in YVO 4 .

Electrochimica Acta, 2012

Dispersed Na 0.6 CoO 2 ·yH 2 O and Li 0.5 CoO 2 powders have been obtained at room temperature by... more Dispersed Na 0.6 CoO 2 ·yH 2 O and Li 0.5 CoO 2 powders have been obtained at room temperature by rapid precipitation in aqueous solutions of LiOH or NaOH in the presence of a strong oxidizer. The precipitates are well crystallized and consist of nanoscale platelets with high specific area (above 100 m 2 /g). The Li 0.5 CoO 2 phase is stable in aqueous electrolytes whereas the Na 0.6 CoO 2 ·yH 2 O rapidly converts to CoOOH in neutral electrolytes or pure water. It also transforms to anhydrous Na 0.6 CoO 2 upon drying at moderate temperatures. Electrochemical studies show that at slow sweep rates the Na 0.6 CoO 2 ·yH 2 O can store large amounts of charge in 10 M NaOH from a combination of both faradic and capacitive reactions.

Nano Letters, 2004

Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological la... more Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological labels. These nanoparticles are synthesized directly in water, which facilitates their functionalization, and are remarkably photostable without emission intermittency. Nanoparticles functionalized with guanidinium groups act as artificial toxins and specifically target sodium channels. They are individually detectable in live cardiac myocytes, revealing a heterogeneous distribution of sodium channels. Functionalized oxide nanoparticles appear to be a novel tool that is particularly attractive for long-term single-molecule tracking.

Meeting Abstracts, Jun 4, 2012

#582, Honolulu PRiME 2012, © 2012 The Electrochemical Society ) unless CC License in place (see a... more #582, Honolulu PRiME 2012, © 2012 The Electrochemical Society ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 54.160.112.150 Downloaded on 2017-03-26 to IP

Journal of Luminescence, 2015

The Journal of Physical Chemistry C, 2015

ABSTRACT The broadband dielectric spectroscopy has been applied, for the first time, to nanoplate... more ABSTRACT The broadband dielectric spectroscopy has been applied, for the first time, to nanoplatelets of NaxCoO2. yH2O. Permittivity and conductivity have been measured on a wide frequency range from a few Hz to microwaves. The effect of hydration state on the electrical transport and ageing (drying and rehydration cycles) on the electrical properties of the NaxCoO2 nanoplatelets is well evidenced. While the sample dehydrated under vacuum (NaxCoO2.0.25 H2O) shows a metallic behavior, it becomes a semiconductor with a thermally activated conduction upon rehydration (NaxCoO2,0.5 H2O). The fully hydrated material (NaxCoO2.0.7 H2O) obtained after synthesis and mild drying at 293 K evidences two sharp and intense conductivity and permittivity resonances above room temperature in the microwave region. We associate these two resonances to Charge Density Waves coupling electronic transport and ionic polarizations associated to the presence of structural water in the NaxCoO2 interlayers.

MRS Proceedings, 2013

Development of devices storing and delivering high-energy power such as supercapacitors is necess... more Development of devices storing and delivering high-energy power such as supercapacitors is necessary to assist intermittent sources of energy. Most of the commercial systems are carbon-based, but due to their high surface charge, oxides offer a valuable alternative for high-rate energy storage. Among them, layered transition metal oxides with mixed valence properties present both good electronic and ionic conductivities suitable for application to electrochemical applications intermediate between capacitors and batteries. This work focuses on lamellar oxide bronzes based on cobalt M x CoO 2 and vanadium M x V 2 O 5 (M = H, Li, Na or K). A low temperature synthesis leads to high specific area particles (above 100 m 2 /g). Hydrated and anhydrous Na x CoO 2 are promising cathode materials for aqueous supercapacitors, with a high capacity of more than 100 mAh/g obtained under 20 mV/s for the hydrated Na x CoO 2 . The M x V 2 O 5 bronzes appear to be good candidates for organic supercapacitors, especially the Li x V 2 O 5 bronze, which shows a high stable capacity above 100 mAh/g (at 20 mV/s ie a charging time of 125 s).

Colloidal Quantum Dots for Biomedical Applications II, 2007

ABSTRACT We report on the single-particle properties of lanthanide-ion doped oxide nanoparticles.... more ABSTRACT We report on the single-particle properties of lanthanide-ion doped oxide nanoparticles. We have demonstrated that their size can be accurately determined from their luminosity. The optically determined size distribution is in very good agreement with the distribution obtained from transmission electron microscopy (TEM). We also showed that the photobleaching of these nanoparticles is related to a reduction process and that we can use it to sense in a concentration-dependent manner the presence of an oxidant like H2O2. Finally, we propose a way to perform nanoparticle-protein coupling and to determine the protein-nanoparticle ratio at the single-particle level.

MRS Proceedings, 2004

Lanthanide-ion doped oxide (YVO 4 :Eu) nanoparticles were synthesized as aqueous colloids and fun... more Lanthanide-ion doped oxide (YVO 4 :Eu) nanoparticles were synthesized as aqueous colloids and functionalized by a bioactive silane shell to be used as fluorescent biological labels. Nanoparticles functionalized with guanidinium groups were able to act as artificial toxins which specifically target Na' channels. They were individually detectable in live cardiac myocytes. Functionalized oxide nanoparticles appear as a new interesting tool, especially attractive for long-term single-molecule tracking due to their photo-stability and long luminescence lifetime. * The composition of the physiological Ringer solution was (mM): NaCI: 1103.5; KCI: 2.5: Ca Cl,: 2; MgC : 1; Na*pyruvate: 5: HEPES (NaOH): 10; glucose: 10; alhumine: I mg/mil; pH: 7.34.

Journal of Power Sources, 2014

A moderate pressure not collapsing porosity strongly improves capacitor performance. Electronic c... more A moderate pressure not collapsing porosity strongly improves capacitor performance. Electronic conductivity of an oxide electrode limits its electrochemical properties. A moderate pressure applied on powder strongly improves grain to grain connectivity. Formulation with carbon additive is mandatory to get high electronic conductivities.

MRS Proceedings, 2007

... molecule. REFERENCES 1. J. Zhang, RE Campbell, AY Ting, RY Tsien, Nat. Rev. Mol. Cell Biol. 2... more ... molecule. REFERENCES 1. J. Zhang, RE Campbell, AY Ting, RY Tsien, Nat. Rev. Mol. Cell Biol. 2002, 3, 906 2. WCW Chan, S. Nie, Science 1998, 281, 2016 M. Bruchez, M. Moronne, P. Gin, S. Weiss, AP Alivisatos Science 1998, 281, 2013. ...

The Journal of Physical Chemistry B, 2006

We used lanthanide-ion doped oxide nanoparticles, Y 0.6 Eu 0.4 VO 4 , as donors in fluorescent re... more We used lanthanide-ion doped oxide nanoparticles, Y 0.6 Eu 0.4 VO 4 , as donors in fluorescent resonance energy transfer (FRET) experiments. The choice of these nanoparticles allows us to combine the advantages of the lanthanide-ion emission, in particular the long lifetime and the large Stokes shift between absorption and emission, with the detectability of the nanoparticles at the single-particle level. Using cyanine 5 (Cy5) organic molecules as acceptors, we demonstrated FRET down to the single-nanoparticle level. We showed that, due to the long donor lifetime, unambiguous and precise FRET measurements can be performed in solution even in the presence of large free acceptor concentrations. Highly efficient energy transfer was obtained for a large number of acceptor molecules per donor nanoparticle. We determined FRET efficiencies as a function of Cy5 concentration which are in good agreement with a multiple acceptor-multiple donor calculation. On the basis of the donor emission recovery due to acceptor photobleaching, we demonstrated energy transfer from single-nanoparticle donors in fluorescence microscopy experiments.

Progress in Solid State Chemistry, 2005

Rare earth doped oxide materials are well known for their numerous applications in light emitting... more Rare earth doped oxide materials are well known for their numerous applications in light emitting devices. An interesting issue is to study the emission properties of nanoparticles, with the aim to understand the influence of small size and surface effects on the emission processes. These particles could furthermore be used in new applications such as the elaboration of transparent emitting devices or new biological labels. The work presented here concerns highly luminescent rare earth doped yttrium vanadates (YVO 4 :Eu) and lanthanum phosphate LaPO 4 :Ce,Tb$xH 2 O nanoparticles. Simple aqueous colloidal syntheses are used for the elaboration of concentrated colloids based on the progressive decomposition of polymeric precursors at moderate temperature (60e90 C). Both types of particles exhibit strong emission (quantum yields of 25% and 45% for vanadates and phosphates, respectively), but significantly lower than that for the equivalent bulk materials. The alteration of the emission processes is discussed in terms of surface quenching effects. Improvements are obtained through the elaboration of core/shell nanostructures. Surface derivatization has been achieved through the controlled growth of an organically modified silica shell using a functionalized silane precursor. Two examples are given concerning the applications of those particles. The first one is the elaboration of transparent and highly luminescent thin films, obtained by the dispersion of the functionalized particles in a solegel silica matrix. The other one is the use of Progress in Solid State Chemistry 33 www.elsevier.com/locate/pssc guanidine functionalized particles as biological labels for the single particle detection of sodium channels in cardiac cells.

Physical Review Letters, 2013

A homogeneous linewidth of 85:6 AE 4:4 kHz is reported in 60 nm Eu 3þ doped Y 2 O 3 nanocrystals ... more A homogeneous linewidth of 85:6 AE 4:4 kHz is reported in 60 nm Eu 3þ doped Y 2 O 3 nanocrystals at 1.3 K. This linewidth was measured by two-pulse photon echoes on highly scattering powders using heterodyne detection. Spectral diffusion was also investigated by three-pulse photon echoes and resulted in a limited broadening of the homogenous linewidth of about 250 kHz over 120 s. Compared to achievable Rabi frequencies, in the range of several MHz, these values show that rare earth doped nanocrystals can be useful for applications in optical quantum information processing.

Nano Letters, 2004

Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological la... more Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological labels. These nanoparticles are synthesized directly in water, which facilitates their functionalization, and are remarkably photostable without emission intermittency. Nanoparticles functionalized with guanidinium groups act as artificial toxins and specifically target sodium channels. They are individually detectable in live cardiac myocytes, revealing a heterogeneous distribution of sodium channels. Functionalized oxide nanoparticles appear to be a novel tool that is particularly attractive for long-term single-molecule tracking.

Langmuir, 2008

Luminescent inorganic nanoparticles are now widely studied for their applications as biological p... more Luminescent inorganic nanoparticles are now widely studied for their applications as biological probes for in vitro or in vivo experiments. The functionalization of the particles is a key step toward these applications, since it determines the control of the coupling between the particles and the biological species of interest. This paper is devoted to the case of rare earth doped oxide nanoparticles and their functionalization through their surface encapsulation with a functional polysiloxane shell. The first step of the process is the adsorption of silicate ions that will act as a primary layer for the further surface polymerization of the silane, either aminopropyltriethoxysilane (APTES) or glycidoxypropyltrimethoxysilane (GPTMS). The amino- or epoxy- functions born by the silane allow the versatile coupling of the particles with bio-organic species following the chemistry that is commonly used in biochips. Special attention is paid to the careful characterization of each step of the functionalization process, especially concerning the average number of organic functions that are available for the final coupling of the particles with proteins. The surface density of amino or epoxy functions was found to be 0.4 and 1.9 functions per square nanometer for GPTMS and APTES silanized particles, respectively. An example of application of the amino-functionalized particles is given for the coupling with alpha-bungarotoxins. The average number (up to 8) and the distribution of the number of proteins per particle are given, showing the potentialities of the functionalization process for the labeling of biological species.

Journal of the American Chemical Society, 2007

coprecipitation as described by Huignard et al., 2000. The obtained nanoparticles were coated by ... more coprecipitation as described by Huignard et al., 2000. The obtained nanoparticles were coated by a thin silica layer that acts as a stabilizer and a primary layer for the further aminosilane functionalization. This silica layer was obtained by the addition of tetramethylammonium silicate ((CH 3 ) 4 NOH.2SiO 2 , Aldrich) into the colloidal solution of Y 0.6 Eu 0.4 VO 4 nanoparticles in a similar way to that demonstrated by Philipse et al., 1994 and Correa-Duarte et al., 1998. We used a large excess of silicate with a concentration about ten times the total vanadate (VO 4 3-) ion concentration. The colloidal dispersion was then left under stirring overnight. It was then purified by dialysis against water for a period of about 100 h in order to remove the excess silicate ions, leaving a thin layer of adsorbed silicate ions. The final conductivity of the solution was about 100 mS·cm -2 .

Journal of Materials Chemistry, 2006

Besides well-known quantum dots, lanthanide-doped oxide nanocrystals form a new promising class o... more Besides well-known quantum dots, lanthanide-doped oxide nanocrystals form a new promising class of nanophosphors. Lanthanide vanadate and phosphate nanoparticles are prepared as welldispersed and highly concentrated colloids by a very simple aqueous route, using competition between precipitation and complexation reactions. Under UV excitation, the three basic colors are furnished by YVO 4 : Eu (red), LaPO 4 : Ce?0.7H 2 O (blue-violet) and LaPO 4 : CeTb?0.7H 2 O (green). In the case of cerium-doped phosphate nanoparticles, the epitaxial growth of a LaPO 4 ?0.7H 2 O shell leads to ''core-shell'' nanocrystals presenting improved stability against cerium oxidation which is detrimental for the luminescence. Nanocrystals exhibiting passivation and chemical or biological functionalization are easily prepared using the silane strategy. The optimized nanophosphors are either dispersed in transparent sol-gel films or used as isolated particles for biological labelling. The luminescence properties of nanoparticles differ from corresponding bulk materials in several ways : (i) spectroscopic changes, as a systematic broadening of the luminescence bands in sub-20 nm nanocrystals, resulting from a structural disorder intrinsic to the small size; (ii) a lower luminescence quantum yield related to the presence of chemical species adsorbed at the surface, especially the OH groups; (iii) a shift towards higher values of the optimum doping concentration, due to the alteration of energy transfers either in the vanadate or cerium sub-networks.

Journal of Luminescence, 2012

Transparent luminescent Y 0.98-x Bi x Eu 0.02 VO 4 (0<x<1) ceramic films have been prepared using... more Transparent luminescent Y 0.98-x Bi x Eu 0.02 VO 4 (0<x<1) ceramic films have been prepared using a polymeric route and heat-treatment at 550°C. A solid solution of zircon-type Y 1-x Bi x VO 4 is obtained for x values below 0.5 whereas phase separation is observed above this limit. The absorption spectra of the films show a shift of the band edge towards high wavelength with the bismuth content, as theoretical calculi have predicted. Luminescence of the films under a UV excitation is typical of europium ion in the zircon structure. The poor correlation between absorption and excitation spectra at high bismuth content is coherent with desexcitation in localized states of valence band. However, the excitation wavelength could still be tuned from deep-UV to near-UV range by inserting bismuth in YVO 4 .

Electrochimica Acta, 2012

Dispersed Na 0.6 CoO 2 ·yH 2 O and Li 0.5 CoO 2 powders have been obtained at room temperature by... more Dispersed Na 0.6 CoO 2 ·yH 2 O and Li 0.5 CoO 2 powders have been obtained at room temperature by rapid precipitation in aqueous solutions of LiOH or NaOH in the presence of a strong oxidizer. The precipitates are well crystallized and consist of nanoscale platelets with high specific area (above 100 m 2 /g). The Li 0.5 CoO 2 phase is stable in aqueous electrolytes whereas the Na 0.6 CoO 2 ·yH 2 O rapidly converts to CoOOH in neutral electrolytes or pure water. It also transforms to anhydrous Na 0.6 CoO 2 upon drying at moderate temperatures. Electrochemical studies show that at slow sweep rates the Na 0.6 CoO 2 ·yH 2 O can store large amounts of charge in 10 M NaOH from a combination of both faradic and capacitive reactions.