Catalytic effects of magnetic and conductive nanoparticles on immobilized glucose oxidase in skin sensors

Abstract

Wearable skin sensors is a promising technology for real-time health care monitoring. They are of particular interest for monitoring glucose in diabetic patients. The concentration of glucose in sweat can be more than two orders of magnitude lower than in blood. In consequence, the scientific and technological efforts are focused in developing new concepts to enhance the sensitivity, decrease the limit of detection (LOD) and reduce the response time (RT) of glucose skin sensors. This work explores the effect of adsorbed superparamagnetic magnetite nanoparticles (MNPs) and conductive nanoparticles (CNPs) on carbon nanotube substrates (CNTs) used to immobilize glucose oxidase enzyme in the working electrode of skin sensors. MNPs and CNPs are made of magnetite and gold, respectively. The performance of the sensors was tested in standard buffer solution, artificial sweat, fresh sweat and on the skin of a healthy volunteer during an exercise session. In the case of artificial sweat, the presence of MNPs accelerated the RT from 7 to 5 s at the expense of increasing the LOD from 0.017 to 0.022 mM with slight increase of the sensitivity from 4.90 to 5.09 μAm M −1 cm −2 . The presence of CNPs greatly accelerated the RT from 7 to 2 s and lowered the LOD from 0.017 to 0.014 mM at the expense of a great diminution of the sensitivity from 4.90 to 4.09 μAm M −1 cm −2 . These effects were explained mechanistically by analyzing the changes in the concentration of free oxygen and electrons promoted by MNPs and CNPs in the CNTs and its consequences on the the glucose oxidation process.

Flexible wearable devices for intelligent health monitoring

“…57 In addition to the above-mentioned electrocatalytic mechanism, flexible photoelectrochemical and piezotransducer-biosensor-based wearable glucose monitoring devices were reported and presented great sensitivity for sweat monitoring (showing compact correlation to glucose level obtained by commercial glucose meter). [58][59][60][61] More significantly, physiological influence of food intake and exercise on glucose level was also investigated, and accurate glucose signals achieved over constructed monitoring devices corroborated their great feasibility and prospect in practical application. 62 Moreover, self-powered and fully integrated smartwatch composed of flexible photovoltaic cells, rechargeable batteries, customized circuits and display units that integrated into a "dial" platform was developed for realtime continuous glucose detection and presented great promising in noninvasive glucose monitoring with in situ real-time signal processing/display.…”

“…In addition to the above‐mentioned electrocatalytic mechanism, flexible photoelectrochemical and piezotransducer‐biosensor‐based wearable glucose monitoring devices were reported and presented great sensitivity for sweat monitoring (showing compact correlation to glucose level obtained by commercial glucose meter) 58‐61 . More significantly, physiological influence of food intake and exercise on glucose level was also investigated, and accurate glucose signals achieved over constructed monitoring devices corroborated their great feasibility and prospect in practical application 62 .…”

Hyperthermic triggers for drug delivery platforms

“…SPMNPs were prepared by a co-precipitation method [24,25]. Briefly, 6.22 g of ferrous chloride and 2.29 g of ferric chloride, in 2:1 Fe3+/Fe2+ ratio, were dissolved in 50 ml of water.…”

“…The recovered material was firstly washed with deionized water and secondly with methanol to remove all Cl-ions and residual ammonium hydroxide. The final product was vacuum dried during 45 min and then stored until use in a hermetically sealed container [24,25].…”

Facile Synthesis of MXene-Ti3C2/Co Nanosheet Hydrogel Sensor with the Assistance of a Smartphone for On-Site Monitoring of Glucose in Beverages

“…Considering that glucose in the human body is mainly derived from food products and beverages, the evaluation of the glucose concentration in food products and beverages is significant to effectively control the intake of glucose and guarantee transparency regarding dietary risks. So far, a variety of analytical techniques for glucose detection have been established, such as colorimetric [ 7 , 8 ], electrochemical [ 9 , 10 ], chemiluminescence [ 11 , 12 ], mass spectrometry [ 13 , 14 ], fluorescence [ 15 , 16 ] and surface-enhanced Raman scattering [ 17 , 18 ] methods. Among these methods, as a rapid, specific and intuitive method, commercial glucose detection kits have been widely used, involving two consecutive enzyme reactions.…”