This technical note describes a method for fabricating ion-selective membranes (ISMs) for use in potentiometric sensing by using 3D printing technology. Here, we demonstrate the versatility of this approach by fabricating ISMs and investigating their performance in both liquid-contact and solid-contact ion-selective electrode (ISE) configurations. Using 3D printed ISMs resulted in highly stable (drift of ∼17 μV/h) and highly reproducible (<1 mV deviation) measurements. Furthermore, we show the seamless translation of these membranes into reliable, carbon fiberand paper-based potentiometric sensors for applications at the point-of-care. To highlight the modifiability of this approach, we fabricated sensors for bilirubin, an important biomarker of liver health; benzalkonium, a common preservative used in the pharmaceutical industry; and potassium, an important blood electrolyte. The ability to mass produce sensors using 3D printing is an attractive advantage over conventional methods, while also decreasing the time and cost associated with sensor fabrication.
Chloroquine is an important, and commonly prescribed, antimalarial drug which can lead to the development of retinopathy and potential blindness. This paper reports on the design and fabrication of a highly selective potentiometric sensor for chloroquine, demonstrating the first use of ionophore-doped ion-selective electrodes (ISEs) for its detection. Several molecules with known affinity for chloroquine were investigated as potential ionophores for the chloroquine ISE. Incorporating melanin as the ionophore resulted in a linear detection range of 10 mM to 2.4 µM and a limit of detection of 630 nM. Importantly, the melanin-doped ISE resulted in an increased selectivity by several orders of magnitude compared to an ionophore-free ISE. This added selectivity allowed for detection of chloroquine without interference from other commonly prescribed antimalarials, hydroxychloroquine, and quinine that have similar molecular structures. To determine the applicability of the melanin-doped ISE, chloroquine was successfully measured in human urine samples, and the results of the sensor were validated using a high-performance liquid chromatography protocol. To demonstrate the utility of the sensor, the components of the ISE were translated to a paper-based potentiometric device capable of detecting chloroquine between 10 mM and 100 µM, covering the biologically relevant range excreted in human urine
This paper describes the design, fabrication, and validation of a paper-based diagnostic device for the rapid diagnosis of hypocalcemia in dairy cattle at the point-of-care (POC). The device incorporates a 3D printed calcium ion-selective membrane (ISM) as the sensing element for free—unbound—calcium in real bovine whole blood samples. With a linear response range of 100 mM to 97.7 µM, the sensor covers the clinically relevant concentrations of Ca2+ associated with both healthy cattle as well as those suffering from hypocalcemia. The components of the Ca2+ ion-selective electrodes were successfully translated to a paper-based device to provide a sensing platform that is simple to use, disposable, and low-cost, and is therefore well-situated for applications at the POC. The paper-based calcium sensor showed a Nernstian response between 10 mM and 100 μM and required only 12 μL of sample to perform a measurement, which can be accomplished in less than two minutes without the need for time-consuming separation steps. The performance of the paper-based Ca2+ sensor was validated using the commercially available epoc® Blood Analysis System, which provided results within 5% of the data obtained with 3D printed Ca2+-ISM integrated paper-based device.
Ion-selective electrodes have been thoroughly studied over the past three decades and have produced analytical devices for the detection of several important analytes (e.g., K+, Na+, bilirubin, etc.) in complex matrices like blood or urine. Most ion-selective electrodes contain a molecular recognition element (i.e., ionophore) to increase selectivity towards a specific analyte. Chloroquine has been used in antimalarial treatments for over 50 years, however, chloroquine has been connected to the onset of retinopathy. Retinopathy is an ophthalmic disease which can lead to partial blindness (i.e., peripheral blindness or night blindness) or, in extreme cases, complete blindness. Currently, expensive benchtop equipment such as HPLC and UV-Vis spectroscopy are used to measure chloroquine levels. Interestingly, although chloroquine is a highly lipophilic molecule, there are no reports of potentiometric sensors being applied towards the detection of chloroquine. This research describes the development of ion-selective electrodes doped with ionophores for the rapid quantification of chloroquine. The investigated ionophores have been previously studied with respect to their binding to chloroquine and show strong indications that they can provide the selectivity required to measure chloroquine in diverse biological fluids. Each chloroquine ion-selective electrode was analyzed for its selectivity, linear detection range, stability, and reproducibility.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.