Biology subjects

Patino, D. U.

Publications and source records attributed to Patino, D. U..

3 recordsLinked to original sources

bioRxiv2026

Direct electrochemical cortisol detection via transition-resolved interrogation at a defect-engineered graphene interface

Continuous tracking of cortisol is central to understanding human stress physiology, yet direct electrochemical detection without biological receptors remains challenging despite its promise for stable and dynamic sensing. Electrochemical reduction of cortisol typically occurs at highly negative potentials, where parasitic interfacial currents, hydrogen evolution, and substantial capacitive background overlap with the cortisol reduction signal, preventing accurate quantification. We overcome this barrier through an integrated material-measurement strategy combining a defect-engineered graphene interface with a transition-resolved interrogation (TRI) measurement strategy. First, we engineered polybenzimidazole-derived laser-induced graphene containing nitrogen-rich defects while suppressing oxygen-derived functionalities which reduced parasitic background currents within the same cathodic potential regime. Next, we designed TRI to leverage differences in the time-dependent evolution of overlapping cathodic processes to isolate a localized cortisol-associated electrochemical reduction transition. Derivative-domain projection coupled with background estimation enables its reliable quantification. This integrated sensing architecture enables sensitive, selective, and dynamic cortisol detection in both artificial and biological interstitial fluids at low nanomolar concentrations. The response remains reproducible across physiologically relevant variations in pH, ionic strength, temperature, and repeated cycling. Together, these capabilities provide a basis for continuous electrochemical cortisol monitoring for future study of stress physiology.

bioengineering↗

bioRxiv2026

Tuning selectivity of electrochemical sensors with polymer coatings

Electrochemical sensors are promising for health monitoring due to their high repeatability and sensitivity, particularly when nanostructured. Yet, their translation into real applications is hindered by limited selectivity in the absence of specific binding receptors: many biomarkers exhibit similar oxidation potentials, producing overlapping voltammetric signals that impede molecular discrimination. Here, we demonstrate that the oxidation potential of several small molecule biomarkers can be controlled through polymeric coatings, specifically poly(4-vinylpyridine), deposited onto glassy carbon electrodes. The polymer coating alters diffusion and adsorption characteristics, which ultimately lead to oxidation potential shifts of ascorbic acid and serotonin, enabling their separation of otherwise overlapping signals. These findings are supported by Chronocoulometry and Fourier-transform infrared spectroscopy analysis that reveal changes in diffusion coefficient, adsorbed charge, and hydrogen bonding that are likely responsible for the altered sensor performance. These findings can be expanded to further polymers and biomarkers, including estradiol and melatonin. Finally, we demonstrate that the same selectivity trends persist on nanostructured, stretchable carbon-flower electrodes, where the high surface area further enhances sensitivity. Collectively, these findings reveal polymer-controlled peak-potential tuning as a powerful and broadly applicable route toward highly selective electrochemical sensors, enabling molecular discrimination in complex mixtures and opening new avenues for sensor-array-based detection.

bioengineering↗

bioRxiv2025

Sensitive Hormone and Neurotransmitter Detection with Carbon Flower Electrodes

Carbon-based electrochemical sensors have attracted substantial attention for continuous health monitoring due to their high surface area, wide potential window, capability for repeated measurements, and compatibility with soft wearable electronics. However, they face challenges when detecting target biomarker concentrations in the low nanomolar range (sensitivity) and differentiating them in a mixture (selectivity), limiting their applicability in real scenarios. Herein, we present sensitive and selective carbon flower sensors, fabricated via a facile and patternable spray-coating process on soft, stretchable substrates. The carbon flowers--obtained through the synthesis of polyacrylonitrile and subsequent heat treatments--exhibit unique hierarchical morphologies, high surface area, and excellent conductivity, ideal for mass transport and electrochemical detection. We demonstrate the detection of estradiol, serotonin, melatonin, dopamine, uric acid, and ascorbic acid with detection limits as low as sub-nanomolar. The carbon flower sensors exhibit good repeatability across 100 cycles and over several weeks, robustness to pH and salt variations, and excellent performance in complex bio-fluids such as artificial saliva. In mixtures containing up to four analytes, they differentiate individual molecules, demonstrating the selectivity of the carbon flowers. This combination of sensitivity, selectivity, and mechanical compatibility makes carbon flower sensors well-suited for biomolecular sensing in soft, skin-conformable wearable electronic patches.

bioengineering↗