On-chip structure-switching aptamer-modified magnetic nanobeads for the continuous monitoring of interferon-gamma ex vivo

Abstract

Cytokines are cell signaling molecules that indicate the health status of the body. In this study, we developed a microfluidic device integrated with structure-switching aptamers capable of continuously tracking the concentration of the cytokine interferon gamma (IFN-γ) in cell culture medium and blood serum. First, a ferrocene (Fc)-labeled structure-switching signaling aptamer with a hairpin structure targeting IFN-γ was immobilized on magnetic nanobeads by the strongest noncovalent interactions between streptavidin and biotin. The aptamer-modified magnetic nanobeads were trapped on a customized microfluidic chip by a magnetic field to form the sensing interface. The binding of IFN-γ could trigger the hairpin structure of the aptamer to unfold, pushing Fc redox molecules away from the sensing interface and consequently switching off the electrochemical signal. The change in the redox current of Fc was quantitatively related to the concentration of IFN-γ in a linear range of 10–500 pg mL−1 and with the lowest detection limit of 6 pg mL−1. This microfluidic device was specific to IFN-γ in the presence of overabundant serum proteins and allowed the continuous monitoring of IFN-γ without adding exogenous reagents. It provided a universal point-of-care biosensing platform for the real-time detection of a spectrum of analytes.

Cytokines: From Clinical Significance to Quantification

“…Such cytokines biosensors [ 124 ] can rely on fluorescence or electrochemical signal readouts to quantify intracellular and extracellular cytokines in non‐real‐time [ 39,125 ] or in real‐time. [ 31,126 ] They can also use other transducing elements. Table 3 compares various biosensors for cytokine detection based on different signaling strategies such as fluorescence immunoassays (FI), surface plasmon resonance detection (SPR), electrochemical‐based methods (EC), surface enhanced Raman spectroscopy (SERS), colorimetric, CRISPR/Cas signal amplification linked immunosorbent assay (CLISA) and other methods, in terms of their performance (i.e., sensitivity, and levels of samples required).…”

“…For immunosensors, structure‐switching aptamer based electrochemical biosensors can also be implemented to realize real‐time cytokines detection. [ 31,36,38 ] Specifically, in order to enhance the sensitivity and robustness of aptamer based cytokine biosensing, the surface nanofabrication and ratiometric measurements are important. [ 126,154 ] Liu et al.…”

Translational control of enzyme scavenger expression with toxin-induced micro RNA switches

“…Most of the recent approaches use an aptamer element to engineer ligand-responsiveness and to regulate gene expression [23][24][25][26]44 . Aptamers are widely used, due to their high binding affinity against their respective target and their specificity [70][71][72][73][74][75][76][77][78][79][80][81][82] . In principal, the process of SELEX (Systematic Evolution of Ligands by Exponential enrichment) allows aptamer selection against any small molecule of interest 83,84 .…”

Point‐of‐care detection of cytokines in cytokine storm management and beyond: Significance and challenges

“…[ 91 ] With the capability of switching the 3D configuration with the presence of the target analyte, structure‐switching aptamers have demonstrated as excellent recognition unit for continuous cytokine monitoring. [ 92–96 ] An electrochemical biosensor based on structure‐switching aptamers against to IFN‐γ was developed for the successful detection of IFN‐γ continuously (Figure 1A). Ideally, a noninvasive way that differs from the conventional brain implantable biosensor, [ 97 ] needs to be explored and the wearable electronics for sweat derived cytokines detection might be a potential direction.…”