Fiber optic pH probe for physiological use

Peterson, John I.; Goldstein, Seth; Fitzgerald, R. V.; Buckhold, Delwin K.

doi:10.1021/ac50056a022

Cited by 451 publications

(127 citation statements)

References 29 publications

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“…Normalized absorption spectra of the R form (1,3) and HR + form (2,4) of neutral red in aqueous solutions at pH 10.0 and 4.0, respectively (1,2) and in the gelatin film at pH 10.5 and 6.0, respectively (3,4). Figure S2.…”

Section: Protolytic Properties Of Dyes Embedded In Gelatin Filmsmentioning

confidence: 99%

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Protolytic properties of dyes embedded in gelatin films

Никитина¹,

Reshetnyak²,

Svetlova³

et al. 2011

J. Braz. Chem. Soc.

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O filme de gelatina endurecida fixo em uma base transparente de triacetilcelulose pode ser utilizado como um suporte conveniente para indicadores ácido-base. Azul de bromofenol, verde de bromocresol, eosina, etil-eosina, n-decil-eosina, n-decil-fluoresceína, vermelho neutro e verde de malaquita foram incorporados nos filmes de gelatina por extração em meio aquoso sob condições apropriadas. A absorção de luz dos filmes dopados com corante exibe uma resposta ao pH de soluções tampão aquosas nas quais foram imersos. Valores reprodutíveis das constantes aparentes de dissociação dos indicadores, pK a app , foram calculados pelo tratamento convencional dos valores de pH do tampão aquoso e também para a água absorvida nos filmes de gelatina. Os experimentos com pH abaixo e acima do ponto isoelétrico da gelatina (em torno de pH 5) resultaram em valores de pK a app semelhantes àqueles em meios micelares de tensoativos catiônicos e aniônicos, respectivamente. Os filmes de gelatina modificados por corantes podem ser recomendados para uso em sensores óticos e dispositivos similares.The hardened gelatin film fixed on the transparent triacetylcellulose support can be utilized as a convenient carrier for acid-base indicator dyes. Bromophenol blue, bromocresol green, eosin, ethyleosin, n-decyleosin, n-decylfluorescein, neutral red, and malachite green were embedded into the gelatin films by extracting from aqueous media under appropriate conditions. The light absorption of dye-doped films exhibits a response to the pH values of aqueous buffer solutions, where they were soaked in. The well-reproducible indices of the apparent ionization constants, pK a app , of the indicators were calculated by conventional equating the pH values of the bulk aqueous buffer and those of the 'internal' water into the gelatin films. The experiments with pH below and above the isoelectric point of gelatin (around pH 5) result in pK a app values, which resemble those in micellar media of cationic and anionic surfactants, respectively. The dye-modified gelatin films can be recommended for use in optical sensors and related devices. Keywords: dye-modified gelatin film, indicators, apparent ionization constants, medium effects IntroductionThis paper is devoted to the influence of hardened gelatin media on the spectral and acid-base properties of immobilized xanthene, sulfonephthalein, and some other dyes.The immobilization of reagents in solid matrix (cellulose, ion-exchangers, polymers, silica, xerogels, etc.) 1-7 or using organized solutions, e.g., surfactant-based ones, [8][9][10][11][12] modifies the properties of guest molecules owing to the change of the microenvironment.Such modifications, or medium effects, are most studied and well documented for acid-base indicators. 8,9 In this case, the influence of the microenvironment results in the shift of the indicator equilibrium as compared to that in aqueous media. The main reasons are the local polarity and the local electrical charge. The latter often (but not always) manifests itself in the decre...

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Section: Protolytic Properties Of Dyes Embedded In Gelatin Filmsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] or using organized solutions, e.g., surfactant-based ones, [8][9][10][11][12] modifies the properties of guest molecules owing to the change of the microenvironment.…”

Section: Introductionmentioning

confidence: 99%

Protolytic properties of dyes embedded in gelatin films

Никитина¹,

Reshetnyak²,

Svetlova³

et al. 2011

J. Braz. Chem. Soc.

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“…Over the past two decades, considerable effort has been directed toward the development of solute specific chemical sensors with optical detection (e.g., Harvey 1957;Peterson et al 1980;Seitz 1984;Lakowicz 1999). These optical sensors are often called optodes (derived from ␦ -the optical way) or optrodes (in analogy to the term electrode).…”

mentioning

confidence: 99%

“…These optical sensors are often called optodes (derived from ␦ -the optical way) or optrodes (in analogy to the term electrode). The first fiber optic pH sensor was developed for in vivo studies by Peterson et al (1980) and related pH to the absorbance of immobilized phenol red (phenolsolfonphtalein). Owing to the general importance of pH measurements, a large number of pH optodes have been designed (e.g., Saari and Seitz 1982;Zhujun and Seitz 1984;Offenbacher et al 1986;Wolfbeis and Offenbacher 1986;Leiner and Wolfbeis 1991).…”

mentioning

confidence: 99%

A pH plate fluorosensor (optode) for early diagenetic studies of marine sediments

Hulth

Aller

Engström

et al. 2002

Limnology & Oceanography

105

102

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Pore water pH distributions are closely coupled to early diagenetic reactions and transport processes in surficial sediments. In this study, an optical plate fluorosensor for rapid two-dimensional detection of H ϩ concentration patterns in sediment pore waters was developed. The dual excitation (405/450 nm) single emission (520 nm) pH fluorophore HPTS (8-hydroxypyrene 1, 3, 6, trisulfonic acid trisodium salt) was immobilized onto transparent, supporting sensor foils. Excitation/emission spectra of immobilized HPTS exhibited pH dependent shifts in seawater standards, and fluorescence excitation ratios were used for two-wavelength, ratiometric detection of pH distributions in sediment and bottom water close to the sediment-water interface (pH ഠ 6.5 to 8.5). Sensor foils were fixed to the inner sides of plastic box corers or glass plate aquaria containing sediment and overlying seawater. Equilibration with pore water occurred in seconds, and fluorescence response (excitation/emission) was scanned nondestructively using a monochrome, integrating CCD camera. The two-dimensional sensor system has a vertical and horizontal resolution of 56 ϫ 54 m (5 ϫ 5 pixels) applied over an image of 34 ϫ 26 mm. Reproducibility and accuracy were best when foils were prepared from solutions of similar ionic strength to samples. Optical sensor pH distributions correlated well with high-resolution, vertical distributions measured simultaneously with a minicombination pH electrode, and two-dimensional pH patterns demonstrated directly the transport-reaction heterogeneity associated with microtopography and biogenic structures in surface deposits and overlying waters close to the sediment-water interface. Sensor foils retained calibration characteristics for at least 50 d.

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“…Of major importance at present are sensors based on optical principles, including absorbance, reflectance, fluorescence, and interferometry. The use of optical fibres to achieve such measurements was an important early development, (10) whereas planar fabrication techniques have also provided many options for complex optical sensor configurations. (11) It is evident that current sensor advances owe much to key technological innovations that have had a particular impact on device fabrication, improving reliability and complexity at the microscale as well as opening the door to nanoscale devices.…”

Section: Introductionmentioning

confidence: 99%

Micro- and Nanosensors for Medical and Biological Measurement

Rolfe¹

2012

Sensors and Materials

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Micro-and nanosensors have evolved rapidly in the last few decades and they have expanding roles within biology and medicine, where measurement science and technology is of key importance. The targets for measurement include a huge number of simple and complex molecules, physical quantities such as pressure, force, displacement and flow, and electrical and magnetic phenomena arising from the heart, brain, muscles and nerves. Routine clinical care of patients currently benefits from the use of macro-and microscale sensors based on electrical, electrochemical, acoustic, piezoelectric and optical principles. Disposable electrodes for recording biopotentials, such as the electrocardiogram and electroencephalogram, are common, whereas invasive electrochemical and optical fibre sensors for pressure, blood gases and pH are useful in intensive care. Microscale immobilised enzyme glucose sensors are largely confined to the analysis of small blood samples, their invasive use still facing technical challenges. Sensors constructed to the nanoscale using quantum dots and carbon nanotubes are now rapidly emerging, being aimed at more complex biomolecules such as DNA. Nanoparticles in general and surface-enhanced Raman spectroscopy also play important roles in these developments. The impact of micro-and nanosensors on the fundamental understanding of major biomedical challenges and on clinical diagnosis and care are highlighted here.

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Fiber optic pH probe for physiological use

Cited by 451 publications

References 29 publications

Protolytic properties of dyes embedded in gelatin films

Protolytic properties of dyes embedded in gelatin films

A pH plate fluorosensor (optode) for early diagenetic studies of marine sediments

Micro- and Nanosensors for Medical and Biological Measurement

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