Endoscopic sensing of alveolar pH
D Choudhury, M G Tanner, S McAughtrie, F Yu, B Mills, T R Choudhary, S Seth, T H Craven, J M Stone, I K Mati, C J Campbell, M Bradley, C K I Williams, K Dhaliwal, T A Birks, R R Thomson, D Choudhury, M G Tanner, S McAughtrie, F Yu, B Mills, T R Choudhary, S Seth, T H Craven, J M Stone, I K Mati, C J Campbell, M Bradley, C K I Williams, K Dhaliwal, T A Birks, R R Thomson
Abstract
Previously unobtainable measurements of alveolar pH were obtained using an endoscope-deployable optrode. The pH sensing was achieved using functionalized gold nanoshell sensors and surface enhanced Raman spectroscopy (SERS). The optrode consisted of an asymmetric dual-core optical fiber designed for spatially separating the optical pump delivery and signal collection, in order to circumvent the unwanted Raman signal generated within the fiber. Using this approach, we demonstrate a ~100-fold increase in SERS signal-to-fiber background ratio, and demonstrate multiple site pH sensing with a measurement accuracy of ± 0.07 pH units in the respiratory acini of an ex vivo ovine lung model. We also demonstrate that alveolar pH changes in response to ventilation.
Keywords: (170.4580) Optical diagnostics for medicine; (170.6510) Spectroscopy, tissue diagnostics.
Figures
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Background suppressed p-MBA SERS spectrum…
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Background suppressed p-MBA SERS spectrum and its characteristics with respect to change in…
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Variation of area under the…
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Variation of area under the curve (AUC) ratio as a function of pH…
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Typical shape of p-MBA SERS,…
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Typical shape of p-MBA SERS, background and residual spectra acquired using the fiber…
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The area under the curve…
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The area under the curve (AUC) ratio obtained at pH 6.4 and 7.4…
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Alveolar space pH measured using…
Fig. 7
Alveolar space pH measured using the fiber-optic optrode in an ex vivo ovine…
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Fabrication stages of the dual…
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Fabrication stages of the dual core fiber. Stage one, the formation of the…
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Source: PubMed