The capacitive sensing of NS1 Flavivirus biomarker

Abstract

NS1 is a biomarker for different Flavivirus diseases such as dengue (DENV), zika (ZIKV) and chikungunya (CHIKV) and was herein selectively quantified by electrochemical capacitive sensing (an impedance-derived capacitance methodology wherein the redox probe is contained in the receptive layer) mainly aiming dengue diagnosis in phosphate buffer saline and blood serum environments (up to the neat level). The capacitive sensing was compared to traditional concurrent impedimetric approach (in which the redox probe is added in the biological solution) and other transient methods stated in the literature regarding figures of merit such as limit of detection, linear range, relative standard deviation and affinity constant. Capacitive and impedimetric assays showed equivalent results for linear range, repeatability, sensitivity and constant of affinity. Nonetheless capacitive assays presented better reproducibility with a relative standard deviation (RSD) of 3±1 and 7±4 (all in percentage) in PBS and serum, respectively, meanwhile for impedimetric assays the RSD values were 9±5 in PBS and 12±6 in serum. Thus, by using capacitive assays, an improvement on the analytical performance was observed with the limit of detection about sixty-fold lower in neat serum (∼0.5ngmL for capacitive over ∼30ngmL for impedimetric assays) compared to traditional electrochemistry methods in general hence demonstrating the superior detection sensitivity for NS1 protein. Accordingly, redox tagged capacitive assays are suitable for the development of multiplex point-of-care neglected diseases sensing applications.

A Capillary Flow Dynamics‐Based Sensing Modality for Direct Environmental Pathogen Monitoring

“…This corresponded to observed increases in immunoagglutination with increasing ZIKV concentration, despite the complexity of the serum matrix. This detection limit is equivalent to that observed in a plasmonic resonance‐based immunosensor, and exceeds those observed by capacitive and impedimetry‐based immunoassays (LOD=0.5–30 ng/mL in serum) . In addition, our assay time is much reduced (30 s) from those described above …”

“…This detection limit is equivalent to that observed in ap lasmonic resonancebased immunosensor, and exceeds those observed by capacitive and impedimetry-based immunoassays (LOD = 0.5-30 ng/ mL in serum). [28,29] In addition, our assay time is much reduced (30 s) from those described above. [28,29] In conclusion, this novel capillary flow-based transducer mechanism shows promise for applicationsi nf ield-deployable diagnostics.…”

“…[28,29] In addition, our assay time is much reduced (30 s) from those described above. [28,29] In conclusion, this novel capillary flow-based transducer mechanism shows promise for applicationsi nf ield-deployable diagnostics. Thism ethodi sd emonstrated for bacterial and viral pathogens, showingc linically relevant sensitivity and specificity even in complexs ample matrices, detecting down to 1log CFU/mL E. coli in water samples and 20 pg/mL ZIKV in serum samples at an operating time of 30 s. With adaptation to other targets of interest, this proposed assay technique can be widely used in field and clinical settings,e nabling users to track the propagation of emergenti nfectious diseases directly from environmental samples in an easy-to-use and affordable manner.…”

Future developments in biosensors for field-ready Zika virus diagnostics

“…Recent immunosensors developed and tested by Cecchetto et al, for example, use impedimetric and capacitive sensing of the NS1 protein from DENV, and have the potential for near immediate conversion to ZIKV detection due to potential cross-reactivity of the anti-NS1 IgG1 antibodies employed [61] (Table 2). Similarly, flavivirus biosensors have been developed using lab-on-a-chip and lab-on-a-CD technology for label-free optical and electrochemical sensing of DENV through serological IgM or NS1 protein binding [62, 63].…”

A dual marker label free electrochemical assay for Flavivirus dengue diagnosis

“…To date a number of low cost diagnostic platforms for NS1 have been reported, including those based on impedimetric analyses (Parkash and Shueb, 2015;Teles, 2011;Wong et al, 2016;Tai et al, 2006;Su et al, 2003;Oliveira et al, 2009;Cecchetto et al, 2015Cecchetto et al, , 2017Darwish et al, 2016). For example, Cecchetto et al (2015) have reported an impedimetric biosensor to detect NS1 both in PBS and serum using a surface tethered anti-NS1 antibody.…”