{'fraction_non_alphanumeric': 0.036607687614399025, 'fraction_numerical': 0.011592434411226357, 'mean_word_length': 5.051660516605166, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Oxygen sensor based on the fluorescence quenching of a ruthenium complex immobilized in a biocompatible Poly(Ethylene glycol) hydrogel

An optically based system has been developed for use as an oxygen sensor for a cell culture bioreactor. Electrochemical sensors based on the Clark oxygen electrode are typically used with cell-culture bioreactors. These sensors, however, are subject to long-term drift, due in part to biofouling, and require penetrating the bioreactor with the probe in order to perform a measurement. We report an implantable sensor that, when used with an external fiber-optic probe, takes advantage of the oxygen stimulated fluorescence quenching of dichloro(tris-1,10-phenanthroline) ruthenium (II) hydrate. This fluorophore was immobilized in a photopolymerized hydrogel made from poly(ethylene glycol) diacrylate (PEG-DA), a polymer known to minimize protein and cell adhesion. A low-average molecular weight PEG-DA (MW = 575) was employed to hinder the fluorophore from leaching. The PEG-DA precursor solution contained 40% H/sub 2/O such that, upon polymerization, the gel was already in the hydrated state. Sensor hydrogels stored in H/sub 2/O for several months retained their physical shape and sensitivity to oxygen. The sensor showed a high degree of reproducibility across a range of oxygen concentrations that are typical for cell culture experiments (0-9.1 ppm O/sub 2/), and a linear model produced a strong correlation (R /sup 2/= 0.995) compared with a commercial electrochemical probe. No drift or hysteresis was identified in the sensor across cycles of varying oxygen concentrations in this range.