A-383 Electrochemical Detection of IL-6 on Canatu functionalized Carbon Nanotube Dry-Printed Electrodes: Preliminary data on linear response across a low-nanogram range

Abstract

Interleukin-6 (IL-6) is a clinically important inflammatory cytokine, and rapid quantification can support early decision-making in a range of acute and chronic conditions. Electrochemical biosensing is a promising route for point-of-care (POC) inflammation assessment due to low sample volume requirements, portability, and fast signal readout. Carbon nanotube (CNT) electrodes provide highly conductive, nanostructured interfaces that can enhance biomolecular capture and electrochemical transduction. Canatu CNT Dry-Printed Electrodes (DPEs) offer a uniform, high surface area CNT network with superior conductivity and mass manufacturing capability, important for highly sensitive and precision biosensing. Here, we report preliminary results from a sandwich immunoassay demonstrating IL-6 detection in phosphate-buffered saline (PBS) in a low-nanogram range, using Canatu CNT DPE sensors. This data supports the feasibility of CNT DPE based electrochemical biosensors for IL-6 and with further optimization of assay chemistry and signal generation conditions, the sensitivity can be significantly improved and the turnaround time (TAT) reduced. Canatu CNT Dry-Printed Electrodes were functionalized using proprietary surface chemistry to immobilize an anti–IL6 capture antibody. Following antibody immobilization and surface blocking, IL-6 standards in PBS (0, 0.625, 1.25, 2.5, 5, and 10 ng/mL) were incubated on the electrodes at room temperature. Detection was performed using a biotinylated anti–IL-6 antibody followed by streptavidin–polyHRP. After each step, electrodes were washed with PBS-Tween20. Chronoamperometry (CA) measurement was initiated immediately after addition of 3,3',5,5'-tetramethylbenzidine (TMB) substrate, using a PalmSens potentiostat for electrochemical readout. Each concentration was measured in triplicate, with PBS used as the blank. The reported metrics were the median CA current, standard deviation (SD), coefficient of variation (CV%), and signal-to-noise ratio. The Canatu CNT DPE platform showed a linear IL-6–dependent current response, supporting its suitability for biomarker detection. Median CA currents (µA) increased in magnitude with IL-6 concentration: PBS blank –0.39; 0.625 ng/mL –5.90; 1.25 ng/mL –13.47; 2.5 ng/mL –17.23; 5 ng/mL –21.79; and 10 ng/mL –25.90. Signal-to-noise ratios increased from 14.95 at 0.625 ng/mL to 65.64 at 10 ng/mL, indicating strong separation from background across the tested range. Precision was concentration dependent, as expected for an early-stage assay: CV% was lowest at 2.5 ng/mL (1.35%) and highest at 0.625 ng/mL (35.4%), consistent with non-optimized surface coverage and assay kinetics. Overall, the monotonic calibration behavior across 0.625–10 ng/mL and the low blank signal support robust, concentration-dependent IL-6 detection in PBS on functionalized Canatu CNT DPEs. These preliminary results indicate that functionalized Canatu CNT Dry-Printed Electrodes provide a robust platform for electrochemical IL-6 detection. The platform generated clear, concentration-dependent chronoamperometric responses across 0.625–10 ng/mL with good separation from the PBS blank, supporting the suitability of CNT DPEs for cytokine and biomarker sensing. While additional optimization is required to improve low-concentration precision, extend dynamic range, and enhance overall reproducibility, the current data establish feasibility and justify continued development. Ongoing work will refine surface chemistry, assay conditions, and signal generation parameters to increase analytical sensitivity in clinically relevant matrices and reduce time-to-result for point-of-care implementation.