Abstract
AbstractThe monitoring of K+ in saliva, blood, urine, or sweat represents a future powerful alternative diagnostic tool to prevent various diseases. However, several K+ sensors are unable to meet the requirements for the development of point‐of‐care (POC) sensors. To tackle this grand‐challenge, the fabrication of chemiresistors (CRs) based on 3D networks of Au nanoparticles covalently bridged by ad‐hoc supramolecular receptors for K+, namely dithiomethylene dibenzo‐18‐crown‐6 ether is reported here. A multi‐technique characterization allows optimizing a new protocol for fabricating high‐performing CRs for real‐time monitoring of K+ in complex aqueous environments. The sensor shows exceptional figures of merit: i) linear sensitivity in the 10–3 to 10–6 m concentration range; ii) high selectivity to K+ in presence of interfering cations (Na+, Ca2+, and Mg2+); iii) high shelf‐life stability (>45 days); iv) reversibility of K+ binding and release; v) successful device integration into microfluidic systems for real‐time monitoring; vi) fast response and recovery times (<18 s), and v) K+ detection in artificial saliva. All these characteristics make the supramolecular CRs a potential tool for future applications as POC devices, especially for health monitoring where the determination of K+ in saliva is pivotal for the early diagnosis of diseases.
Highlights
The Potassium cation (K+) is one of the most abundant physiological metal ions in living organisms, playing vital roles in many biological processes, such as blood pressure control, digestion, nerve conduction, regulation of muscle contractions, osmoregulation, heartbeat, etc.[1]
Chemiresistor Fabrication and Operation The assembly of the 3D covalent network for the fabrication of CRs relies on two key components: i) citrate-stabilized Au NPs [29] (Figures S1-2), and ii) a dithiomethylene dibenzo18-crown-6 ether, DTDB-18C6 (Scheme S1, Figures S3-7)
The former endows the sensing platform with excellent electrical features for signal transduction,[11b] whereas the latter guarantees the covalent linkage of adjacent Au NPs and the supramolecular recognition of K+ via well-known host−guest interactions. [27,28] The fabrication of the CRs has been the subject of a deep investigation in order to optimize its overall sensing performance
Summary
The Potassium cation (K+) is one of the most abundant physiological metal ions in living organisms, playing vital roles in many biological processes, such as blood pressure control, digestion, nerve conduction, regulation of muscle contractions, osmoregulation, heartbeat, etc.[1]. To the best of our knowledge, few examples of CRs based on metal NPs for ion sensing (viz. Cu2+,[24] and Zn2+, Cd2+, and CH3Hg+) have been published so far.[25] these devices rely on the strong complex formation between the receptor and the cations of interest operating in dry state Such a technology satisfies the demand for single-use (i.e., disposable) sensors, but it cannot provide a sound option for continuous, real-time monitoring of the analyte of interest. The successful K+ detection in saliva endows such a CR the required characteristics to be used as the sensing element in future technologies for alternative health monitoring and early diagnostics of diseases
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