Constraint Coupling of Redox Cascade and Electron Transfer Synchronization on Electrode‐Nanosensor Interface for Repeatable Detection of Tumor Biomarkers

Abstract

Quantitative analysis of up‐regulated biomarkers in pathological tissues is helpful to tumor surgery yet the loss of biomarker extraction and time‐consuming operation limited the accurate and quick judgement in preoperative or intraoperative diagnosis. Herein, an immobilization‐free electrochemical sensing platform is developed by constraint coupling of electron transfer cascade on electrode‐nanosensor interface. Specifically, electrochemical indicator (Ri)‐labeled single‐stranded DNA on electroactive nanodonor (polydopamine, PDA) can be responsively detached by formation of DNA complex through the recognition and binding with targets. By applying the oxidation potential of Ri, nanosensor collisions on electrode surface trigger a cascade redox cycling of PDA and Ri through synchronous electron transfer, which boost the amplification of current signal output. The developed nanosensor exhibit excellent linear response toward up‐regulated biomarkers (miRNA‐21, ATP, and VEGF) with low detection limits (32 fM, 386 pM, and 2.8 pM). Moreover, background influence from physiological interferent is greatly reduced by restricted electron transfer coupling on electrode. The practical applicability is illustrated in sensitive and highly repeatable profiling of miRNA‐21 in lysate of tumor cells and tumor tissue, beneficial for more reliable diagnosis. This electrochemical platform by employing electron transfer cascades at heterogeneous interfaces offers a route to anti‐interference detection of biomarkers in tumor tissues.

Electroactive polymer tag modified nanosensors for enhanced intracellular ATP detection

“…A variety of methods have been developed for the detection of ATP, such as colorimetry, 11 fluorescence, 12,13 bioluminescence, 14,15 surface-enhanced Raman scattering, 16 and electrochemical methods. [17][18][19][20] In general, ATP measurements based on optical methods are effective in the determination of ATP in populations of cells and visualizing ATP distribution at single cell/subcellular resolution. Electrochemical biosensors, owing to their good quantitative ability, have been used for detecting ATP in cell lysates.…”

“…Electrochemical biosensors, owing to their good quantitative ability, have been used for detecting ATP in cell lysates. 17,18 Microsized biosensors were also placed outside cells but they cannot readily reflect the exact concentration of intracellular ATP and its biological effects in living cells due to the relatively large size of the electrodes. In contrast, nanoelectrochemical analytical methods are characterized by their high temporal-spatial resolution and are commonly used for the analysis of physiological processes at the single-cell and even subcellular levels.…”