Epidermal Enzymatic Biosensors for Sweat Vitamin C: Toward Personalized Nutrition

Abstract

Recent advances in wearable sensor technologies offer new opportunities for improving dietary adherence. However, despite their tremendous promise, the potential of wearable chemical sensors for guiding personalized nutrition solutions has not been reported. Herein, we present an epidermal biosensor aimed at following the dynamics of sweat vitamin C after the intake of vitamin C pills and fruit juices. Such skin-worn noninvasive electrochemical detection of sweat vitamin C has been realized by immobilizing the enzyme ascorbate oxidase (AAOx) on flexible printable tattoo electrodes and monitoring changes in the vitamin C level through changes in the reduction current of the oxygen cosubstrate. The flexible vitamin C tattoo patch was fabricated on a polyurethane substrate and combined with a localized iontophoretic sweat stimulation system along with amperometric cathodic detection of the oxygen depletion during the enzymatic reaction. The enzyme biosensor offers a highly selective response compared to the common direct (nonenzymatic) voltammetric measurements, with no effect on electroactive interfering species such as uric acid or acetaminophen. Temporal vitamin C profiles in sweat are demonstrated using different subjects taking varying amounts of commercial vitamin C pills or vitamin C-rich beverages. The dynamic rise and fall of such vitamin C sweat levels is thus demonstrated with no interference from other sweat constituents. Differences in such dynamics among the individual subjects indicate the potential of the epidermal biosensor for personalized nutrition solutions. The flexible tattoo patch displayed mechanical resiliency to multiple stretching and bending deformations. In addition, the AAOx biosensor is shown to be useful as a disposable strip for the rapid in vitro detection of vitamin C in untreated raw saliva and tears following pill or juice intake. These results demonstrate the potential of wearable chemical sensors for noninvasive nutrition status assessments and tracking of nutrient uptake toward detecting and correcting nutritional deficiencies, assessing adherence to vitamin intake, and supporting dietary behavior change.

Soft, skin-interfaced microfluidic systems with integrated immunoassays, fluorometric sensors, and impedance measurement capabilities

“…These conditions disrupt the cortisol-melatonin circadian rhythm. As a result, the hypothalamus region of the brain produces corticotropin-releasing hormone, which in turn activates the hypothalamic-pituitary-adrenal axis and stimulates anterior pituitary activity (23,24,66), thereby increasing cortisol production and disrupting of cortisol circadian rhythm (67). The cortisol levels for subjects 2, 3, and 4 during intensive work show disruptions of circadian rhythm, consistent with physiological conditions that reflect exhaustion ( Fig.…”

“…Related designs that incorporate capillary burst valves and mechanically reinforced stiffening materials (e.g., skeletal designs) enable time sequential analysis (i.e., chronosampling) of multiple sweat biomarkers, and application in demanding scenarios that involve physical impacts (17)(18)(19), respectively. In other demonstrations, surfacecoated electrodes with antibody-and enzyme-based assays capture information about cortisol and related biochemicals in a continuous mode of operation, although without field studies to demonstrate robustness of operation required for practical applications (20)(21)(22)(23).…”

Screen-Printed Electrodes: Promising Paper and Wearable Transducers for (Bio)Sensing

“…Wang’s group has reported very recently an epidermal AAOx biosensor able to monitor the dynamics of vitamin C in sweat after the intake of vitamin C pills and fruit juices [ 89 ]. This method combines the use of a flexible vitamin C tattoo patch fabricated on a polyurethane substrate with a localized iontophoretic sweat stimulation system.…”

Pancreatic Cancer (PDAC): Introduction of Evidence-Based Complementary Measures into Integrative Clinical Management

“…An important development in monitoring of nutritional or disease status is use of wearable devices [ 362 ]. A flexible ‘tattoo’ patch was recently shown to be capable of measuring vitamin C levels in sweat as means of tracking the body’s vitamin C status to facilitate any necessary correction of nutritional deficiencies [ 363 ].…”