10 research outputs found
Development of a Fiber Optic Sensor for Online Monitoring of Thin Coatings
 The thickness measurement of gas, liquid and solid layers is not only important for the basic research on nanoscience but equally valuable in contemporary applied biomedical research. Here, we have developed an optical spectroscopy based technique for the online monitoring of thin films (coatings). A low cost light emitting diode (LED) source combined with a fiber optic bundle and grating based spectrograph have been used to generate white light interferogram. We have monitored online change of refractive index of an air film (~4 μm thickness) with temperature following the change in the intensity profile of the interferogram. A thin film of water between two cover slips (thin glass plates) has also been monitored. We have proposed a schematic for further lowering the cost of the developed instrument for the online monitoring of the coating thickness (semitransparent liquid/gas/solid films) during manufacturing/processing. A brief theoretical analysis on the detection limit of the developed technique has also been discussed in the paper
Validation study for measuring absorption and reduced scattering coefficients by means of laser-induced backscattering imaging
Decoupling of optical properties appears challenging, but vital to get better insight of the relationship between light and fruit attributes. In this study, nine solid phantoms capturing the ranges of absorption (μ a ) and reduced scattering (μ s ’) coefficients in fruit were analysed non-destructively using laser-induced backscattering imaging (LLBI) at 1060 nm. Data analysis of LLBI was carried out on the diffuse reflectance, attenuation profile obtained by means of Farrell's diffusion theory either calculating μ a [cm ⁻¹ ] and μ s ’ [cm ⁻¹ ] in one fitting step or fitting only one optical variable and providing the other one from a destructive analysis. The nondestructive approach was approved when calculating one unknown coefficient non-destructively, while no ability of the method was found to analysis both, μ a and μ s ’, non-destructively. Setting μ s ’ according to destructive photon density wave (PDW) spectroscopy and fitting μ a resulted in root mean square error (rmse) of 18.7% in comparison to fitting μ s ’ resulting in rmse of 2.6%, pointing to decreased measuring uncertainty, when the highly variable μ a was known. The approach was tested on European pear, utilizing destructive PDW spectroscopy for setting one variable, while LLBI was applied for calculating the remaining coefficient. Results indicated that the optical properties of pear obtained from PDW spectroscopy as well as LLBI changed concurrently in correspondence to water content mainly. A destructive batch-wise analysis of μ s ’ and online analysis of μ a may be considered in future developments for improved fruit sorting results, when considering fruit with high variability of μ s ’
Spectroscopic Studies on Dual Role of Natural Flavonoids in Detoxification of Lead Poisoning: Bench-to-Bedside Preclinical Trial
Ubiquitousness in
the target organs and associated oxidative stress
are the most common manifestations of heavy-metal poisoning in living
bodies. While chelation of toxic heavy metals is important as therapeutic
strategy, scavenging of increased reactive oxygen species, reactive
nitrogen species and free radicals are equally important. Here, we
have studied the lead (Pb) chelating efficacy of a model flavonoid
morin using steady-state and picosecond-resolved optical spectroscopy.
The efficacy of morin in presence of other flavonoid (naringin) and
polyphenol (ellagic acid) leading to synergistic combination has also
been confirmed from the spectroscopic studies. Our studies further
reveal that antioxidant activity (2,2-diphenyl-1-picrylhydrazyl assay)
of the Pb–morin complex is sustainable compared to that of
Pb-free morin. The metal–morin chelate is also found to be
significantly soluble compared to that of morin in aqueous media.
Heavy-metal chelation and sustainable antioxidant activity of the
soluble chelate complex are found to accelerate the Pb-detoxification
in the chemical bench (in vitro). Considering the synergistic effect
of flavonoids in Pb-detoxification and their omnipresence in medicinal
plants, we have prepared a mixture (SKP17LIV01) of flavonoids and
polyphenols of plant origin. The mixture has been characterized using
high-resolution liquid chromatography assisted mass spectrometry.
The mixture (SKP17LIV01) containing 34 flavonoids and 76 other polyphenols
have been used to investigate the Pb detoxification in mouse model.
The biochemical and histopathological studies on the mouse model confirm
the dual action in preclinical studies
Photothermomechanical Nanopump: A Flow-Through Plasmonic Sensor at the Fiber Tip
Optical fibers equipped
with plasmonic flow sensors at their tips
are fabricated and investigated as photothermomechanical nanopumps
for the active transport of target analytes to the sensor surface.
The nanopumps are prepared using a bottom-up strategy: i.e., by sequentially
stacking a monolayer of a thermoresponsive polymer and a plasmonic
nanohole array on an optical fiber tip. The temperature-dependent
collapse and swelling of the polymer is used to create a flow-through
pumping mechanism. The heat required for pumping is generated by exploiting
the photothermal effect in the plasmonic nanohole array upon irradiation
with laser light (405 nm). Simultaneous detection of analytes by the
plasmonic sensor is achieved by monitoring changes in its optical
response at longer wavelengths (∼500–800 nm). Active
mass transport by pumping through the holes of the plasmonic nanohole
array is visualized by particle imaging velocimetry. Finally, the
performance of the photothermomechanical nanopumps is investigated
for two types of analytes, namely nanoscale objects (gold nanoparticles)
and molecules (11-mercaptoundecanoic acid). In the presence of the
pumping mechanism, a 4-fold increase in sensitivity was observed compared
to the purely photothermal effect, demonstrating the potential of
the presented photothermomechanical nanopumps for sensing applications
Photothermomechanical Nanopump: A Flow-Through Plasmonic Sensor at the Fiber Tip
Optical fibers equipped
with plasmonic flow sensors at their tips
are fabricated and investigated as photothermomechanical nanopumps
for the active transport of target analytes to the sensor surface.
The nanopumps are prepared using a bottom-up strategy: i.e., by sequentially
stacking a monolayer of a thermoresponsive polymer and a plasmonic
nanohole array on an optical fiber tip. The temperature-dependent
collapse and swelling of the polymer is used to create a flow-through
pumping mechanism. The heat required for pumping is generated by exploiting
the photothermal effect in the plasmonic nanohole array upon irradiation
with laser light (405 nm). Simultaneous detection of analytes by the
plasmonic sensor is achieved by monitoring changes in its optical
response at longer wavelengths (∼500–800 nm). Active
mass transport by pumping through the holes of the plasmonic nanohole
array is visualized by particle imaging velocimetry. Finally, the
performance of the photothermomechanical nanopumps is investigated
for two types of analytes, namely nanoscale objects (gold nanoparticles)
and molecules (11-mercaptoundecanoic acid). In the presence of the
pumping mechanism, a 4-fold increase in sensitivity was observed compared
to the purely photothermal effect, demonstrating the potential of
the presented photothermomechanical nanopumps for sensing applications
Photothermomechanical Nanopump: A Flow-Through Plasmonic Sensor at the Fiber Tip
Optical fibers equipped
with plasmonic flow sensors at their tips
are fabricated and investigated as photothermomechanical nanopumps
for the active transport of target analytes to the sensor surface.
The nanopumps are prepared using a bottom-up strategy: i.e., by sequentially
stacking a monolayer of a thermoresponsive polymer and a plasmonic
nanohole array on an optical fiber tip. The temperature-dependent
collapse and swelling of the polymer is used to create a flow-through
pumping mechanism. The heat required for pumping is generated by exploiting
the photothermal effect in the plasmonic nanohole array upon irradiation
with laser light (405 nm). Simultaneous detection of analytes by the
plasmonic sensor is achieved by monitoring changes in its optical
response at longer wavelengths (∼500–800 nm). Active
mass transport by pumping through the holes of the plasmonic nanohole
array is visualized by particle imaging velocimetry. Finally, the
performance of the photothermomechanical nanopumps is investigated
for two types of analytes, namely nanoscale objects (gold nanoparticles)
and molecules (11-mercaptoundecanoic acid). In the presence of the
pumping mechanism, a 4-fold increase in sensitivity was observed compared
to the purely photothermal effect, demonstrating the potential of
the presented photothermomechanical nanopumps for sensing applications
Photothermomechanical Nanopump: A Flow-Through Plasmonic Sensor at the Fiber Tip
Optical fibers equipped
with plasmonic flow sensors at their tips
are fabricated and investigated as photothermomechanical nanopumps
for the active transport of target analytes to the sensor surface.
The nanopumps are prepared using a bottom-up strategy: i.e., by sequentially
stacking a monolayer of a thermoresponsive polymer and a plasmonic
nanohole array on an optical fiber tip. The temperature-dependent
collapse and swelling of the polymer is used to create a flow-through
pumping mechanism. The heat required for pumping is generated by exploiting
the photothermal effect in the plasmonic nanohole array upon irradiation
with laser light (405 nm). Simultaneous detection of analytes by the
plasmonic sensor is achieved by monitoring changes in its optical
response at longer wavelengths (∼500–800 nm). Active
mass transport by pumping through the holes of the plasmonic nanohole
array is visualized by particle imaging velocimetry. Finally, the
performance of the photothermomechanical nanopumps is investigated
for two types of analytes, namely nanoscale objects (gold nanoparticles)
and molecules (11-mercaptoundecanoic acid). In the presence of the
pumping mechanism, a 4-fold increase in sensitivity was observed compared
to the purely photothermal effect, demonstrating the potential of
the presented photothermomechanical nanopumps for sensing applications
Photothermomechanical Nanopump: A Flow-Through Plasmonic Sensor at the Fiber Tip
Optical fibers equipped
with plasmonic flow sensors at their tips
are fabricated and investigated as photothermomechanical nanopumps
for the active transport of target analytes to the sensor surface.
The nanopumps are prepared using a bottom-up strategy: i.e., by sequentially
stacking a monolayer of a thermoresponsive polymer and a plasmonic
nanohole array on an optical fiber tip. The temperature-dependent
collapse and swelling of the polymer is used to create a flow-through
pumping mechanism. The heat required for pumping is generated by exploiting
the photothermal effect in the plasmonic nanohole array upon irradiation
with laser light (405 nm). Simultaneous detection of analytes by the
plasmonic sensor is achieved by monitoring changes in its optical
response at longer wavelengths (∼500–800 nm). Active
mass transport by pumping through the holes of the plasmonic nanohole
array is visualized by particle imaging velocimetry. Finally, the
performance of the photothermomechanical nanopumps is investigated
for two types of analytes, namely nanoscale objects (gold nanoparticles)
and molecules (11-mercaptoundecanoic acid). In the presence of the
pumping mechanism, a 4-fold increase in sensitivity was observed compared
to the purely photothermal effect, demonstrating the potential of
the presented photothermomechanical nanopumps for sensing applications