Ultra-sensitive optical oxygen sensors for characterization of nearly anoxic systems

Lehner, Philipp; Staudinger, Christoph; Borisov, Sergey M.; Klimant, Ingo

doi:10.1038/ncomms5460

Cited by 169 publications

(128 citation statements)

References 28 publications

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“…Without resolving submicromolar concentrations, the linear extrapolation of the O 2 -gradient from above 1 to 2 lmol O 2 L -1 (the lower detection limit of many sensors) to zero O 2 severely underestimates the true extension of the submicromolar zone by up to several meters (online resource 2) and lowers the estimated depth of the oxic/anoxic interface. These observations are relevant for the interpretation of suboxic zones that are defined by the absence of both O 2 and H 2 S. If revisited with sensitive profiling equipment, such zones will probably turn out to be much thinner or even non-existing and processes like the oxidation of methane might actually occur at submicromolar O 2 concentrations rather than by anaerobic pathways (Canfield and Thamdrup 2009;Bethke et al 2011;Lehner et al 2014). …”

Section: Discussionmentioning

confidence: 99%

Redox gradients at the low oxygen boundary of lakes

et al. 2014

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The distribution of oxygen (O 2 ) at the oxic/ anoxic interface in the water column of two Swiss lakes was measured with sub-micromolar sensitivity, high precision, and high spatial resolution. The O 2 distribution was found to be highly variable and it is shown that N-cycling and the redox gradients of Mn, Fe and CH 4 are controlled by O 2 distributions down to the nanomolar concentration range. The profiles reveal that apparent gaps between the oxic zone and the sites of CH 4 and Mn oxidation are bridged by zones with 0.01-1 lmol L -1 O 2 concentrations and thus CH 4 and Mn oxidation clearly occur at oxic conditions. Directly below the steep oxycline of Lake Rot a broad low O 2 zone in the depth range of 6-7.5 m was now detectable. The O 2 increase during daylight in this zone was comparable to the O 2 flux along the oxycline. Here photosynthesis could be responsible for a substantial part of the chemotrophic oxidation processes. An even broader zone (0.8-3.8 m) with sub-micromolar O 2 and evidence for methanotrophic and lithotrophic activities found at 160 m depth in the deep, dark hypolimnion of Lake Zug was maintained by transport, reaction-and mixing processes. The submicromolar zones could not have been resolved with traditional CTD-profiles. Their existence expands the oxic zone downwards and implies that substantial parts of ''suboxic zones'' characterized by the absence of both O 2 and H 2 S may actually belong to the realm of oxic processes if more sensitive measurement techniques are used for their characterization.

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Section: Discussionmentioning

confidence: 99%

Redox gradients at the low oxygen boundary of lakes

et al. 2014

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“…to β-diketones) which dramatically reduces non-radiative deactivation of the excited triplet state. Indeed, the related work demonstrates that the BF 2 -chelated HPhN possesses extraordinary long phosphorescence decay time of about 300 ms. [73] Thus, back energy transfer is unlikely to significantly reduce the luminescence quantum yields and the main deactivation passway is the emission from 5 D 0 level of Eu(III). However, the back energy transfer may be responsible for extraordinary efficient quenching by molecular oxygen which will be discussed below.…”

Section: Absorption Spectramentioning

confidence: 99%

Exceptional Oxygen Sensing Properties of New Blue Light‐Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

Borisov

Fischer

Saf

et al. 2014

Adv Funct Materials

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New europium(III) and gadolinium(III) complexes bearing 8-hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state-of-the-art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow-band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g. in multi-analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state-ofthe-art oxygen indicators particularly for such applications as e.g. food packaging.

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“…Moreover, they are not susceptible to drift caused by consumption of oxygen by the sensing dye. 32,49,50 In this study, an oxygen-sensitive fluorophore, [Ru(dpp) 3 ] 2þ Cl 2 -tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) chloride (Sigma-Aldrich), was used as the oxygen indicator, due to its high photostability and moderate brightness. 33 It has a maximum excitation at a wavelength of 463 nm, while the maximum emission occurs at 618 nm.…”

Section: Fabrication Of Oxygen Sensormentioning

confidence: 99%

A microfluidic optical platform for real-time monitoring of pH and oxygen in microfluidic bioreactors and organ-on-chip devices

et al. 2016

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There is a growing interest to develop microfluidic bioreactors and organ-on-chip platforms with integrated sensors to monitor their physicochemical properties and to maintain a well-controlled microenvironment for cultured organoids. Conventional sensing devices cannot be easily integrated with microfluidic organ-on-chip systems with low-volume bioreactors for continual monitoring. This paper reports on the development of a multi-analyte optical sensing module for dynamic measurements of pH and dissolved oxygen levels in the culture medium. The sensing system was constructed using low-cost electro-optics including light-emitting diodes and silicon photodiodes. The sensing module includes an optically transparent window for measuring light intensity, and the module could be connected directly to a perfusion bioreactor without any specific modifications to the microfluidic device design. A compact, user-friendly, and low-cost electronic interface was developed to control the optical transducer and signal acquisition from photodiodes. The platform enabled convenient integration of the optical sensing module with a microfluidic bioreactor. Human dermal fibroblasts were cultivated in the bioreactor, and the values of pH and dissolved oxygen levels in the flowing culture medium were measured continuously for up to 3 days. Our integrated microfluidic system provides a new analytical platform with ease of fabrication and operation, which can be adapted for applications in various microfluidic cell culture and organ-on-chip devices.

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Ultra-sensitive optical oxygen sensors for characterization of nearly anoxic systems

Cited by 169 publications

References 28 publications

Redox gradients at the low oxygen boundary of lakes

Redox gradients at the low oxygen boundary of lakes

Exceptional Oxygen Sensing Properties of New Blue Light‐Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

A microfluidic optical platform for real-time monitoring of pH and oxygen in microfluidic bioreactors and organ-on-chip devices

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