Chloride and sodium ion concentrations in saliva and sweat as a method to diagnose cystic fibrosis

Abstract

Saliva chloride concentration and saliva sodium concentration are candidates to be used in cystic fibrosis diagnosis, mainly in cases where it is difficult to achieve the correct sweat amount, and/or CFTR mutation screening is difficult, and/or reference methods for sweat test are unavailable to implement or are not easily accessible by the general population.

Wireless, Flexible, Ion-Selective Electrode System for Selective and Repeatable Detection of Sodium

“…While real-time detection was enabled by deploying a Bluetooth low-energy module, a thin selective membrane electrode directly formed on a Cu contact pad on the flexible circuit showed excellent selectivity and long-term stability of sensitivity desired for repeatable use. The flexible sodium sensor exhibited near-Nernstian sensitivity of 56 mV/decade in sodium concentrations from 10 −4 to 1 M, covering a typical spectrum of saliva [5,6,36,37]. on calibration protocols and corresponding saliva detection, multiple times.…”

“…As illustrated in Figure 1c, the resulting saliva concentration was in the range of the reported values analyzed by commercial bulky devices. Specifically, normal saliva sodium level is in the range of 4 to 37 mM [36,37] and 6 to 35 mM [5,6] via photonic and electrochemical detection, respectively. The measured sodium concentration from our sensor ranged from 6.5 to 11.8 mM (7 times), which was consistent with the reported range.…”

“…Unlike the case of bulky devices, the thin-film ISE in this work showed great applicability for a wearable, portable system, along with wireless data acquisition, mechanical flexibility, and repeatable sensing capabilities. Comparison of measured sodium levels between commercial bulky devices (1-4) and our wireless system, where reference 1: 8.7-24 mM (generally known) [36], reference 2:4-37 mM (photometer) [37], reference 3:6-35 mM (electrochemical luminescence) [5], reference 4:10-13 mM (electrochemical ISE) [6], and our wireless film ISE: 6.5-11.8 mM. Figure 2 shows fabrication procedures for the film ISE, and verification strategies for the flexible structural designs.…”

“…Wireless, flexible film-based ion-selective electrodes (ISEs) have great potential for replacing existing bulky equipment with a miniaturized and mobile system for many clinical applications based on noninvasive measurements [1][2][3]. Selective detection of sodium in sweat and saliva, correlated to its level in blood [4], has been used for disease diagnosis (e.g., cystic fibrosis and cardiovascular risk) [5,6]. However, it is still very challenging for flexible film ISEs to offer repeatable and accurate measurements over an extended period since they are vulnerable to chemical and mechanical deformation.…”

Vibrational Spectroscopy for Identification of Metabolites in Biologic Samples

“…In fact, the use of sweat in the diagnosis of cystic fibrosis has been well documented and its use as a diagnostic biofluid in other diseases, such as Addison’s disease, Parkinson’s disease, and schizophrenia has been inferred [ 88 , 90 ]. Raman spectroscopy has identified significant variance among unique sweat samples resulting from amino acids, proteins, and metabolites in the samples [ 91 ]. Figure 3 reflects the slight variation from seven different sweat samples.…”