Integration of Multiple Redox Centers into Porous Coordination Networks for Ratiometric Sensing of Dissolved Oxygen

Abstract

The application of porphyrin metal−organic frameworks (MOFs) as a ratiometric electrochemical sensing platform is still unexplored. In this paper, we report a ratiometric electrochemical sensor by the integration of multiple redox centers into porphyrin MOFs for the detection of dissolved oxygen (DO). Specifically, the ferrocene (Fc) group was integrated into the nanosized PCN-222(Fe) (PCN = porous coordination networks) via acid−base reaction to synthesize the Fc@PCN-222(Fe) composite with two redox centers of the Fc group and Fe-porphyrin. The Fc group that is insensitive to DO serves as an internal reference, and the Feporphyrin in PCN-222(Fe) is a DO indicator. The ratios of the cathodic currents for the two redox centers exhibit a linear relationship with DO concentrations from 2.8 to 28.9 mg mL −1 and a limit of detection of 0.3 mg mL −1 . In addition, the ratiometric electrochemical sensor has high selectivity and stability for DO sensing results from the Fc@PCN-222(Fe) composite. Because there are numerous redox centers, such as methylene blue and thionine, which can be integrated into MOFs, many MOF-based ratiometric electrochemical sensors can be simply developed for high-performance biosensing.

Engineering Single-Atom Sites into Pore-Confined Nanospaces of Porphyrinic Metal–Organic Frameworks for the Highly Efficient Photocatalytic Hydrogen Evolution Reaction

“…Crystal engineering of metal–organic frameworks (MOFs) for specific purposes such as adsorption, separation, sensing, and catalysis, including electro-/photocatalysis, has aroused increasing interest and achieved much development in recent decades. − Especially, MOFs based on Zr-oxo clusters have attracted considerable attention due to their excellent chemical and thermal stability, which is attributed to the strong Zr­(IV)–O bonds. − Functional units can be anchored in the nodes, linkers, or cavities of these Zr-MOFs. First, the dangling hydroxyl and aqua ligands on the Zr-oxo clusters can be utilized as grafting sites for catalytic species, either organocatalysts or metal complexes. − Second, a range of catalyst supporters, such as salen, porphyrin, and bipyridine, can be incorporated into the linkers, thus endowing the MOFs with excellent physiochemical properties. For example, a lot of porphyrinic MOFs are reported as efficient photocatalysts owing to their ability to absorb visible light with a remarkably long lifetime of the triplet excited state. − Third, different kinds of active species, such as metal nanoparticles (M-NPs) and metal complexes, can be immobilized in the cavities of MOFs, which impart the resulting MOF composites with better performances than the MOF itself due to the synergistic effect of different components. − …”

A Facile One-Pot Synthetic Approach Towards CB@PCN-222(Fe) Composites for Simultaneous Electrochemical Detection of Dihydroxybenzene Isomers

“…S7, when the oxygen concentration in PBS increased from N 2 -to O 2 -saturated, there was a clear cathodic current response at the desired potential, which was contributed by the electrocatalytic activity of Fe-TCPP. 46 In contrast, the GCE modified with CB successfully identified the three isomers with oxidation potentials at 0.0, 0.15 and 0.55 V corresponding to HQ, CC and RC. Nevertheless, oxidation currents of isomers were almost equal to those of PCN-222(Fe)/GCE.…”

Application and Development Prospect of Nanoscale Iron Based Metal-Organic Frameworks in Biomedicine

“…The modification of electroactive ligands, other electroactive materials, or metal nanoparticles is a vital research direction to increase the electrochemical activity of sensors. 93 , 101 , 102 , 108 Optical sensors, Fe-MOF have good oxidase-like catalytic performance, can be applied to colorimetric detection of color detection, and have the advantages of simple, fast, cheap, and direct visual readout. 94 , 97–99 , 104 , 109 It has been widely used in the detection of enzymes, 98 , 106 DNA, 94 hydrogen peroxide, 95 , 100 , 109 glucose, 89 , 96 , 103 and so on.…”

“…The modification of electroactive ligands, other electroactive materials, or metal nanoparticles is a vital research direction to increase the electrochemical activity of sensors. 93 , 101 , 102 , 108 …”