2 research outputs found
Highly Selective Sub-ppm Naked-Eye Detection of Hydrazine with Conjugated-1,3-Diketo Probes: Imaging Hydrazine in Drosophila Larvae
A pair
of pyrene- and anthracene-based turn-on fluorescent probes
(<b>1</b> and <b>2</b>, respectively) reported here can
be easily synthesized in a single-step process and also exhibit outstanding
sensing behavior toward hydrazine over various competing nucleophilic
species and environmentally relevant ions. The probes display dramatic
enhancements in the emission intensity with as high as 83- and 173-fold
increases in the presence of hydrazine. Nitrogenous bases, thiols,
and lanthanides do not interfere in the fluorometric detection. These
probes enable the detection of hydrazine with the naked eye well below
sub-ppm concentrations (ca. 30 ppb) with analytical detection limits
of 5.4 ppb for <b>1</b> and 7.7 ppb for <b>2</b>, which are far exceeded by the accepted lower limit for hydrazine (10 ppb) set by
the US EPA. Simple paper strips based on these probes could be used
for the detection of hydrazine even in the gas phase. Both of the
probes could selectively detect hydrazine even in pond water samples
efficiently. The probes were successfully applied to visualize, for
the first time, accumulation of hydrazine in live fruit-fly larvae using epifluorescence microscopy.
The novel and interesting detection mechanism, proposed on the basis
of spectroscopic evidence and single crystal XRD results, indicates
that the detection pathway proceeds via the initial step of a five-membered
ring formation upon attack of the hydrazine, followed by a dehydration
step for gaining aromaticity
Protein-Based Electronic Skin Akin to Biological Tissues
Human skin provides an interface
that transduces external stimuli into electrical signals for communication
with the brain. There has been considerable effort to produce soft,
flexible, and stretchable electronic skin (E-skin) devices. However,
common polymers cannot imitate human skin perfectly due to their poor
biocompatibility, biofunctionality, and permeability to many chemicals
and biomolecules. Herein, we report on highly flexible, stretchable,
conformal, molecule-permeable, and skin-adhering E-skins that combine
a metallic nanowire (NW) network and silk protein hydrogel. The silk
protein hydrogels offer high stretchability and stability under hydration
through the addition of Ca<sup>2+</sup> ions and glycerol. The NW
electrodes exhibit stable operation when subjected to large deformations
and hydration. Meanwhile, the hydrogel window provides water and biomolecules
to the electrodes (communication between the environment and the electrode).
These favorable characteristics allow the E-skin to be capable of
sensing strain, electrochemical, and electrophysiological signals