This study reports a microfluidic chip-based wearable colorimetric
sensor for detecting sweat glucose. The device consisted of five microfluidic
channels branching out from the center and connected to the detection
microchambers. The microchannels could route the sweat excreted from
the epidermis to the microchambers, and each of them was integrated
with a check valve to avoid the risk of the backflow of the chemical
reagents from the microchamber. The microchambers contained the pre-embedded
glucose oxidase (GOD)–peroxidase–o-dianisidine
reagents for sensing the glucose in sweat. It was found that the color
change caused by the enzymatic oxidation of o-dianisidine
could show a more sensitive response to the glucose than that of the
conventional GOD–peroxidase–KI system. This sensor could
perform five parallel detections at one time. The obtained linear
range for sweat glucose was 0.1–0.5 mM with a limit of detection
of 0.03 mM. The sensor was also used to detect the glucose in sweat
samples from a group of subjects engaged in both fasting and postprandial
trials. The results showed that our wearable colorimetric sensor can
reveal the subtle differences existing in the sweat glucose concentration
after the fasting and the oral glucose uptake.
Mercury (Hg), as a highly harmful
environmental pollutant, poses
severe ecological and health risks even at low concentrations. Accurate
and sensitive methods for detecting Hg2+ ions in aquatic
environments are highly needed. In this work, we developed a highly
sensitive fluorescence sensor for Hg2+ detection with an
integrated use of biosynthetic CdSe/CdS quantum dots (QDs) and liposome
carrier signal amplification. To construct such a sensor, three single-stranded
DNA probes were rationally designed based on the thymine–Hg2+–thymine (T–Hg2+–T) coordination
chemical principles and by taking advantage of the biocompatibility
and facile-modification properties of the biosynthetic QDs. Hg2+ could be determined in a range from 0.25 to 100 nM with
a detection limit of 0.01 nM, which met the requirements of environmental
sample detection. The sensor also exhibited a high selectivity for
Hg2+ detection in the presence of other high-level metal
ions. A satisfactory capacity of the sensor for detecting environmental
samples including tap water, river water, and landfill leachate was
also demonstrated. This work opens up a new application scenario for
biosynthetic QDs and holds a great potential for environmental monitoring
applications.
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