2 research outputs found
Surface-Enhanced Raman Spectroscopy on Liquid Interfacial Nanoparticle Arrays for Multiplex Detecting Drugs in Urine
The design and application
of liquid interfacial plasmonic platform
is still in its infancy but is an exciting topic in tunable optical
devices, sensors, and catalysis. Here, we developed an interfacial
surface-enhanced Raman scattering (SERS) platform through the large-scale
self-assembly of gold nanoparticle (GNP) arrays at the cyclohexane
(CYH)/water interface for detecting trace drug molecules in the urine
of humans. The molecules extracted by the CYH phase from a urine sample
were directly localized into the self-organized plasmonic hotspots,
yielded excellent Raman enhancement, and realized the substrate-free
interfacial SERS detection. Synchrotron radiation small-angle X-ray
scattering (SR-SAXS) experiments reveals a good uniformity of approximately
2–3 nm interparticle distance in the GNP arrays. SERS colocalization
experiments demonstrated that amphetamine molecules of different concentration
levels could be loaded into the interfacial GNP arrays and realized
the coassembly together with nanoparticles at the liquid/liquid interface.
Interfacial GNP arrays with dynamic nanogaps in liquid interfacial
structure can make surrounding molecules easily diffuse into the nanogaps.
In contrast, the fixed GNP arrays on Si wafer were more irregular,
such as multilayer stack, random aggregates, and voids, during the
drying process. When the drugs directly participate in the self-assembly
process, it becomes easier for analytes diffusing into the nanogaps
of GNP arrays, produces a concentration effect, and amplified the
SERS sensitivity. This feature also enables molecules to be adsorbed
evenly in the arrays and makes a more uniform distribution of both
the analytes and GNPs in the liquid interface and realizes the significant
increase in signal reproducibility. Interfacial SERS produced a standard
deviation of 12.5% at 1001 cm<sup>–1</sup> peak of methamphetamine
(MAMP) molecules under the concentration of 1 ppm, implying a good
reproducibility. Moreover, dual-analyte detection at organic and aqueous
phases was also realized and confirmed a good capability for analytes
detection by liquid interfacial SERS platform, which promises nonengineering
detection of analytes dissolved in often-inaccessible environments
Tuning the Interfacial Thermal Conductance between Polystyrene and Sapphire by Controlling the Interfacial Adhesion
In polymer-based electric microdevices,
thermal transport across polymer/ceramic interface is essential for
heat dissipation, which limits the improvement of the device performance
and lifetime. In this work, four sets of polystyrene (PS) thin films/sapphire
samples were prepared with different interface adhesion values, which
was achieved by changing the rotation speeds in the spin-coating process.
The interfacial thermal conductance (ITC) between the PS films and
the sapphire were measured by time domain thermoreflectance method,
and the interfacial adhesion between the PS films and the sapphire,
as measured by a scratch tester, was found to increase with the rotation
speed from 2000 to 8000 rpm. The ITC shows a similar dependence on
the rotation speed, increasing up to a 3-fold from 7.0 ± 1.4
to 21.0 ± 4.2 MW/(m<sup>2</sup> K). This study demonstrates the
role of spin-coating rotation speed in thermal transport across the
polymer/ceramic interfaces, evoking a much simpler mechanical method
for tuning this type of ITC. The findings of enhancement of the ITC
of polymer/ceramic interface can shed some light on the thermal management
and reliability of macro- and microelectronics, where polymeric and
hybrid organic–inorganic nano films are employed