Lehner Philipp, Staudinger Christoph, Borisov Sergey M, Regensburger Johannes, Klimant Ingo
Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, NAWI Graz, Stremayrgasse 9, 8010 Graz (Austria).
Chemistry. 2015 Mar 2;21(10):3978-86. doi: 10.1002/chem.201406037. Epub 2015 Jan 28.
Optical oxygen sensing is of broad interest in many areas of research, such as medicine, food processing, and micro- and marine biology. The operation principle of optical oxygen sensors is well established and these sensors are routinely employed in lab and field experiments. Ultratrace oxygen sensors, which enable measurements in the sub-nanomolar region (dissolved oxygen), are becoming increasingly important. Such sensors prominently exhibit phenomena that complicate calibration and measurements. However, these phenomena are not constrained to ultratrace sensors; rather, these effects are inherent to the way optical oxygen sensors work and may influence any optical oxygen measurement when certain conditions are met. This scenario is especially true for applications that deal with high-excitation light intensities, such as microscopy and microfluidic applications. Herein, we present various effects that we could observe in our studies with ultratrace oxygen sensors and discuss the reasons for their appearance, the mechanism by which they influence measurements, and how to best reduce their impact. The phenomena discussed are oxygen photoconsumption in the sensor material; depletion of the dye ground state by high-excitation photon-flux values, which can compromise both intensity and ratiometric-based measurements; triplet-triplet annihilation; and singlet-oxygen accumulation, which affects measurements at very low oxygen concentrations.
光学氧传感在医学、食品加工以及微生物学和海洋生物学等众多研究领域中备受关注。光学氧传感器的工作原理已广为人知，并且这些传感器在实验室和现场实验中经常被使用。能够在亚纳摩尔区域（溶解氧）进行测量的超痕量氧传感器正变得越来越重要。这类传感器显著地表现出一些会使校准和测量复杂化的现象。然而，这些现象并不局限于超痕量传感器；相反，这些效应是光学氧传感器工作方式所固有的，并且在满足某些条件时可能会影响任何光学氧测量。对于涉及高激发光强度的应用，如显微镜和微流控应用，这种情况尤其如此。在此，我们展示了在使用超痕量氧传感器的研究中观察到的各种效应，并讨论了它们出现的原因、影响测量的机制以及如何最好地减少它们的影响。所讨论的现象包括传感器材料中的氧光消耗；高激发光子通量值导致染料基态的耗尽，这可能会影响强度测量和基于比率的测量；三重态 - 三重态湮灭；以及单线态氧积累，它会影响极低氧浓度下的测量。
