Untitled

Hungerford, Graham; Pereira, M.; Ferreira, João F.; Viseu, Teresa; Coelho, Ana; Isabel, M.; Ferreira, Carla; Suhling, Klaus

doi:10.1023/a:1021361909772

Cited by 18 publications

(17 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The composition of the film and previous work employing light to interact with silver ions 15,19,20 indicate that the most likely explanation is the formation of silver structures within the silica film and an investigation was undertaken to verify this. Irradiation of aqueous solutions of silver ions (and it should be noted that sol-gel derived media produced via our reaction have been shown to retain solvents) 30,31 can induce the photooxidation of water along with the formation of silver atoms (Ag 0 ). These in turn can aggregate to produce silver clusters (Ag 0 ) n and colloids (Ag 0 ) c and can be represented by the following scheme: 32…”

Section: Resultsmentioning

confidence: 99%

In situ formation of silver nanostructures produced via laser irradiation within sol–gel derived films and their interaction with a fluorescence tagged protein

Hungerford

Toury

McLoskey

et al. 2010

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

The presence of a conducting metal surface is known to affect the emission of a fluorophore in its proximity. This can lead to an enhancement in its fluorescence intensity along with a decrease in the fluorescence lifetime. This phenomenon, sometimes known as metal enhanced fluorescence, has implications in the area of sensing and "lab on a chip" applications. Here controlled, localised use of metallic structures can be advantageous in enhancing the detection of a fluorescent signal. The sol-gel technique has been demonstrated as a useful method by which to produce a biocompatible material. The versatility of the reaction allows for the inclusion of metal ions, which can form metallic nanostructures permitting the potential enhancement of fluorescence to be exhibited. In this work we incorporate silver nitrate within silica sol-gel derived films produced using a simple procedure at relative low temperatures (close to ambient). A compact time-resolved fluorescence microscope equipped with a semiconductor laser was used to photoactivate the silver ions to form localised metallic structures within the films. Patterning was achieved by computer control of the microscope stage and using the laser in CW mode. The films were characterised using AFM and UV-vis spectroscopy to ascertain the presence of the photoactivated silver nanostructures. The effect of the presence of these structures was elucidated by studying the time-resolved fluorescence of FITC labelled bovine serum albumin adsorbed to the films, where a decrease in the lifetime of the FITC label was observed in the location of the nanostructures.

show abstract

Section: Resultsmentioning

confidence: 99%

In situ formation of silver nanostructures produced via laser irradiation within sol–gel derived films and their interaction with a fluorescence tagged protein

Hungerford

Toury

McLoskey

et al. 2010

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Such a decrease in Soret band intensity and broadening has been observed previously for aluminum(III)-tetraphenylporphyrin encapsulated in a sol-gel matrix and was attributed to the formation of aggregated porphyrin species. 33 In addition, optical spectra of a concentrated solution of aluminum(III)-tetraphenylporphyrin, measured in organic solvent (e.g., ethanol), exhibit a similar Soret band broadening, which was explained by porphyrin aggregation. 33 Indeed, Soret band broadening and molar absorpitivity decreases have been reported for variety of porphyrin systems that form aggregates.…”

Section: Spectral Properties Of Films Doped With Al[oep]mentioning

confidence: 94%

Fluoride-Selective Optical Sensor Based on Aluminum(III)−Octaethylporphyrin in Thin Polymeric Film: Further Characterization and Practical Application

Badr

Meyerhoff

2005

Anal. Chem.

View full text Add to dashboard Cite

More detailed analytical studies of a new fluoride selective optical sensor based on the use of aluminum(III)-octaethylporphyrin and a lipophilic pH indicator (4′,5′-dibromofluorescein octadecyl ester; ETH-7075) within a thin plasticized poly(vinyl chloride) film are reported. The sensor exhibits extraordinary optical selectivity for fluoride over a wide range of other anions, including anions with far more positive free energies of hydration (e.g., perchlorate, thiocyanate, nitrate, etc.). UV-VIS spectrophotometric studies of the sensing films indicate that fluoride interacts with the Al(III) center of the porphyrin structure, yielding both a change in the Soret band λ max of the porphyrin as well as a change in the protonation state of the pH indicator within the film. The same change in spectral properties of the metalloporphyrin occurs in the absence of added pH indicator or with added tetraphenylborate derivative anionic sites, but optical responses to fluoride in these cases are shown to be irreversible. The presence of the pH indicator and the simultaneous fluoride/proton coextraction equilibrium chemistry is shown to greatly enhance the reversibility of fluoride binding to the Al(III) porphyrin. Optical response toward fluoride can be observed in the range of 0.1 μM to 1.6 mM. Optical selectivity coefficients of < 10 −6 for common anions (e.g., sulfate, chloride, nitrate etc.) and < 10 −4 for perchlorate and thiocyanate are obtained. Measurements of fluoride in drinking water via the new optical sensor are shown to correlate well with values obtained for the same samples using a classical LaF 3 based fluoride ion-selective electrode method.

show abstract

“…Molecular diffusion in micro- and mesoporous materials has been the subject of many experimental investigations, using techniques such as pulsed field gradient NMR, quasi-elastic neutron scattering, , vibrational spectroscopy, , fluorescence anisotropy, , excimer fluorescence, , or fluorescence recovery after bleaching . The problem is that although the distribution of pore sizes in silica gels may be controlled to some extent by varying the conditions of synthesis, notably the pH and amount of excess water, we know from, for example, transmission electron micrographs, that there is a distribution of pore sizes and shapes .…”

Section: Introductionmentioning

confidence: 99%

Diffusion of Single Streptocyanine Molecules in the Nanoporous Network of Sol−Gel Glasses

et al. 2004

View full text Add to dashboard Cite

A new streptocyanine dye has been doped into monolithic silica gels with different porosities, characterized by nitrogen adsorption isotherms. Single-molecule tracking with a wide-field fluorescence microscope is used to determine the diffusivity of the dye in the nanoporous network of the host. The majority of molecules in the gel with wider pores (22 nm) diffuse freely with an average diffusion coefficient of D = 4.7 × 10-9 cm2 s-1. Most of those in the gel with narrower pores (3 nm) are trapped in regions ranging in size from 50 nmthe positioning accuracy of the setupup to 200 nm. Others are alternately trapped and freely diffusing with an average D = 3.5 × 10-10 cm2 s-1. The significance of the distribution of diffusion coefficients measured by single-molecule tracking is discussed. Besides traps, the wide spread of the diffusion coefficients for individual molecules in both gels reveals pronounced microscopic inhomogeneities.

show abstract

Untitled

Cited by 18 publications

References 53 publications

In situ formation of silver nanostructures produced via laser irradiation within sol–gel derived films and their interaction with a fluorescence tagged protein

In situ formation of silver nanostructures produced via laser irradiation within sol–gel derived films and their interaction with a fluorescence tagged protein

Fluoride-Selective Optical Sensor Based on Aluminum(III)−Octaethylporphyrin in Thin Polymeric Film: Further Characterization and Practical Application

Diffusion of Single Streptocyanine Molecules in the Nanoporous Network of Sol−Gel Glasses

Contact Info

Product

Resources

About