Sweat analysis by means of minimally invasive wearable sensors is considered a potentially disruptive method for assessing clinical parameters, with exciting applications in early medical diagnostics and high-performance sports. Electrochemical sensors and biosensors are especially attractive because of the possibility of the electronic integration of wearable devices. In this article, we review several aspects regarding the potentialities and present limitations of electrochemical sweat (bio)sensors, including: the main target analytes and their relationships with clinical conditions; most usual electrochemical techniques of transduction used according to the nature of the target analytes; issues connected to the collection of representative sweat samples; aspects regarding the associated, miniaturized electronic instrumentation used for signal processing and communication; and signal processing by machine learning.
1 November 2021 in Sensors and Actuators B: Chemical
This work presents the synthesis and characterization of oriented nanofibers made of polycaprolactone (PCL) and multiwalled carbon nanotubes (MWCNT) obtained by electrospinning. The preparation of MWCNT/PCL solutions and electrospinning conditions were studied in order to maximize electrical conductivity of the composite and fiber alignment. The characterization of MWCNT/PCL solutions and fibers revealed the occurrence of different dispersion states for MWCNTs for different loads, which in turn affected the properties of the electrospun composite, such as its double electrical percolation and the in-fiber orientation of the PCL crystals. As the same dispersion states of MWCNT were present in both PCL/MWCNT dispersions and fibers, the rheology of the former can be correlated to the final properties of the latter.
In this article, we introduce the use of a carboxy-functionalized waterborne carbon nanotube ink for the fabrication of an amperometric biosensor aimed at the quantification of β-lactoglobulin. Detection of this protein from cow’s milk was performed by a sandwich immunoassay onto printed carbon nanotube electrodes. The electrodes were printed using a carbon nanotube ink modified with polystyrene beads containing a high amount of carboxylic groups for protein immobilization. This strategy showed enhanced sensing performance compared to the use of oxidative treatments for the functionalization of electrodes. These electrodes showed an excellent electrochemical behavior, and proteins could be immobilized on their surface via the carbodiimide reaction. These antibody-immobilized carbon nanotube electrodes allowed for the detection of β-lactoglobulin in sub-ppm concentrations.
The absolute stereochemistry of novel chiral N-(2-hydroxylalkyl)acrylamides prepared by a lipase-catalyzed resolution was successfully determined by 1H NMR of their MTPA esters. The method was validated for this particular case by computational experiments.