Recent improvements to the selectivity of extraction-based optical ion sensors

Robinson, Kye J.; Soda, Yoshiki; Bakker, Eric

doi:10.1039/d1cc06636f

Cited by 13 publications

(14 citation statements)

References 63 publications

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“…Consequently, X3 + will not easily form an interaction with free DNNS – , which explains the optical response. Binding constants in emulsified nanosensors are normally lower than that in a cast membrane of the same matrix material − owing to the ability of the surfactant to bind to competing ions in analogy to an ionophore. , In this case, binding is very strong, and although it will be weaker for a nanoparticle-based system, it may be sufficient for practical applications.…”

Section: Resultsmentioning

confidence: 99%

“…Figure b,c shows the colorimetric response of the DNNS – and TFPB – -based nanosensors as a function of pH in the presence of 10 mM arginine. As discussed in the literature, , multiple equilibrium constants were required to draw the theoretical curves (Figure b,c, black lines). As previously reported, a weighted average of their logarithmic values was used to fit the data .…”

Section: Resultsmentioning

confidence: 99%

“…7−10 The performance (selectivity, sensitivity) and materials science of the latter has undergone vast improvements throughout the last decade. 11 The success of nanoscale ISOs in the last decade was mainly achieved through sensing of small inorganic ions such as alkali ions (Li + , K + , Na + ) and biologically relevant ions (Ca 2+ , Mg 2+ , Cl − , NO 3 − , etc. ), while work involving polyionic species had made limited progress.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Ion-selective optodes (ISOs) have emerged as an optical variant of ion-selective electrodes (ISEs) in the 1990. , Early ISOs typically took the form of polymeric films − and was followed more recently by the development of nano/microparticle-based sensors. − The performance (selectivity, sensitivity) and materials science of the latter has undergone vast improvements throughout the last decade …”

Section: Introductionmentioning

confidence: 99%

“…), while work involving polyionic species had made limited progress. This was ascribed to the poorer selectivity of ligands that were used in polyion sensors relative to the established ionophores for detecting small ions. − The rich scientific field of developing ionophores for small ions was assisted by a significant number of relevant naturally occurring ionophores providing numerous reference points for researchers. In contrast, ionophores for polyionic species have limited examples in nature.…”

Section: Introductionmentioning

confidence: 99%

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Response Mechanism of Hyperpolarization-Based Polyion Nanosensors

2022

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The last decade has witnessed a rapid development of nano- and microparticle-based optical ion sensors, including ion-selective optodes (ISOs). While the application of nano-ISOs has shown promising performance for sensing inorganic ions, polyion sensing using nanoscale ISOs has encountered significant interference in complex samples such as blood plasma. Recently, we have reported on a new polyion sensing principle that operates through a novel mechanism to overcome this challenge. The new sensing mechanism showed improved characteristics not observed with conventional ion-exchange type sensors, but the precise mechanism of operation remained thus far unclear. This paper aims to clarify how protamine, the arginine-rich target polycation, behaves during optical signal transduction to give dramatically improved selectivity. Based on thermodynamic data, sensor performance and ζ-potential analysis, two discrete phases of protamine extraction are identified. Initially, protamine extracts into the bulk nanosensor phase, a process that is concurrent with the optical signal change. This is then followed by protamine accumulation onto the nanosensor surface, which starts only upon saturation of the optical signal change. The data indicate that the improved selectivity is due to the inability of small ions to form a sufficiently strong interaction with an active sensing ingredient, DNNS–. Any exchange of one inorganic cation for another therefore remains optically silent, suppressing matrix effects. Moreover, the recognition of protamine is shown to be an exhaustive extraction process, making the response independent of the nature and concentration of the initial small cation in the nanosensor phase.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Response Mechanism of Hyperpolarization-Based Polyion Nanosensors

2022

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A Tunable Colorimetric Carbon Dioxide Sensor Based on Ion‐Exchanger‐ and Chromoionophore‐Doped Hydrogel

Zhang

Zhai

et al. 2023

Analysis & Sensing

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We report here a colorimetric carbon dioxide (CO2) optode sensor with a polypropylene microporous membrane on top of a thin layer (30 μm) of polyurethane hydrogel. The diffusion of CO2 across the polypropylene membrane induced pH changes in the hydrogel containing a lipophilic indicator, a cation exchanger, and a cationic amine. The ratio of the indicator and the cation exchanger was successfully utilized to adjust the sensitivity of the CO2 response. Increasing the relative amount of the cation exchanger made the sensor much more sensitive to CO2 in the lower concentration range. Moreover, the carbarmic formation reaction between the primary amine and CO2 was investigated. The results indicated a very small contribution of carbarmic formation to the overall pH change. With a detection limit of 0.014 % for the CO2 partial pressure, the sensor was successful applied to monitor CO2 evolution during yeast catalyzed flour fermentation.

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