12 research outputs found
Electrospun Nanofiber Mats as “Smart Surfaces” for Desorption Electrospray Ionization Mass Spectrometry (DESI MS)-Based Analysis and Imprint Imaging
In this paper, desorption
electrospray ionization mass spectrometry
(DESI MS)-based molecular analysis and imprint imaging using electrospun
nylon-6 nanofiber mats are demonstrated for various analytical contexts.
Uniform mats of varying thicknesses composed of ∼200 nm diameter
fibers were prepared using needleless electrospinning. Analytical
applications requiring rapid understanding of the analytes in single
drops, dyes, inks, and/or plant extracts incorporated directly into
the nanofibers are discussed with illustrations. The possibility to
imprint patterns made of printing inks, plant parts (such as petals,
leaves, and slices of rhizomes), and fungal growth on fruits with
their faithful reproductions on the nanofiber mats is illustrated
with suitable examples. Metabolites were identified by tandem mass
spectrometry data available in the literature and in databases. The
results highlight the significance of electrospun nanofiber mats as
smart surfaces to capture diverse classes of compounds for rapid detection
or to imprint imaging under ambient conditions. Large surface area,
appropriate chemical functionalities exposed, and easiness of desorption
due to weaker interactions of the analyte species are the specific
advantages of nanofibers for this application
A Critical Review on Materials for Solid Oxide Fuel Cell Components
Solid-oxide fuel cells are efficient devices for the conversion of chemical to electrical energy and a typical solid-oxide fuel cell consists of a solid electrolyte, cathode, and anode. In the last few decades, researchers have been working extensively on materials development for different components of these devices. In this review article, we briefly discuss the requirements for different components and review prominent materials families explored by the scientific community. As the search for greener energy alternatives such as solid-oxide fuel cells have intensified manifold due to the climate change emergency, a substantial literature was produced on the materials development of these devices and, therefore, we believe a brief review article dedicated to the same will be valuable for the scientific community, particularly new young entrant researchers in the field
Organic Solvent-Free Fabrication of Durable and Multifunctional Superhydrophobic Paper from Waterborne Fluorinated Cellulose Nanofiber Building Blocks
In view of a great demand for paper-based technologies, nonwettable fibrous substrates with excellent durability have drawn much attention in recent years. In this context, the use of cellulose nanofibers (CNFs), the smallest unit of cellulosic substrates (5-20 nm wide and 500 nm to several microns in length), to design waterproof paper can be an economical and smart approach. In this study, an eco-friendly and facile methodology to develop a multifunctional waterproof paper via the fabrication of fluoroalkyl functionalized CNFs in the aqueous medium is presented. This strategy avoids the need for organic solvents, thereby minimizing cost as well as reducing safety and environmental concerns. Besides, it widens the applicability of such materials as nanocellulose-based aqueous coatings on hard and soft substrates including paper, in large areas. Water droplets showed a contact angle of 160° (±2°) over these surfaces and rolled off easily. While native CNFs are extremely hydrophilic and can be dispersed in water easily, these waterborne fluorinated CNFs allow the fabrication of a superhydrophobic film that does not redisperse upon submersion in water. Incorporated chemical functionalities provide excellent durability toward mechanochemical damages of relevance to daily use such as knife scratch, sand abrasion, spillage of organic solvents, etc. Mechanical flexibility of the chemically modified CNF composed paper remains intact despite its enhanced mechanical strength, without additives. Superhydrophobicity induced excellent microbial resistance of the waterproof paper which expands its utility in various paper-based technologies. This includes waterproof electronics, currency, books, etc., where the integrity of the fibers, as demonstrated here, is a much-needed criterion.Peer reviewe
Electrohydrodynamic Assembly of Ambient Ion-Derived Nanoparticles to Nanosheets at Liquid Surfaces
We describe an ambient
ion-based method to create free-standing
metal nanosheets, which in turn are composed of nanoparticles of the
corresponding metal. These nanoparticle-nanosheets (NP-NSs) were formed
by the electrospray deposition (ESD) of metal ions on a liquid–air
interface leading to nanoparticles that self-organize under the influence
of electrohydrodynamic flows, driven by the electric field induced
by the applied potential. Such a two-dimensional organization of noble
metals is similar to the assembly of molecules at liquid–air
interface and has the possibility of creating a category of new materials
useful for diverse applications. Enhanced catalytic activity of the
formed NP-NSs for Suzuki–Miyaura coupling reaction was demonstrated,
which was attributed to their large surface-to-volume ratios
Synthesis of Silicon Nanoparticles from Rice Husk and their Use as Sustainable Fluorophores for White Light Emission
Silicon
nanoparticles (Si NPs) exhibiting observable luminescence have many
electronic, optical, and biological applications. Owing to reduced
toxicity, they can be used as cheap and environmentally friendly alternatives
for cadmium containing quantum dots, organic dyes, and rare earth-based
expensive phosphors. Here, we report an inexpensive silicon precursor,
namely rice husk, which has been employed for the synthesis of Si
NPs by rapid microwave heating. The Si NPs of ∼4.9 nm diameter
exhibit observable green luminescence with a quantum yield of ∼60%.
They show robust storage stability and photostability and have constant
luminescence during long-term UV irradiation extending over 48 h,
in contrast to other luminescent materials such as quantum dots and
organic dyes which quenched their emission over this time window.
Green luminescent Si NPs upon mixing with synthesized red and blue
luminescent Si NP species are shown to be useful for energy-efficient
white light production. The resulting white light has a color coordinate
of (0.31, 0.27) which is close to that of pure white light (0.33,
0.33). The performance of our white light emitting material is comparable
to that of a commercial white light emitting diode (WLED) bulb and
is shown to be better than that of a commercial compact fluorescent
lamp (CFL)
Electrohydrodynamic Assembly of Ambient Ion-Derived Nanoparticles to Nanosheets at Liquid Surfaces
We describe an ambient
ion-based method to create free-standing
metal nanosheets, which in turn are composed of nanoparticles of the
corresponding metal. These nanoparticle-nanosheets (NP-NSs) were formed
by the electrospray deposition (ESD) of metal ions on a liquid–air
interface leading to nanoparticles that self-organize under the influence
of electrohydrodynamic flows, driven by the electric field induced
by the applied potential. Such a two-dimensional organization of noble
metals is similar to the assembly of molecules at liquid–air
interface and has the possibility of creating a category of new materials
useful for diverse applications. Enhanced catalytic activity of the
formed NP-NSs for Suzuki–Miyaura coupling reaction was demonstrated,
which was attributed to their large surface-to-volume ratios
Approaching Sensitivity of Tens of Ions Using Atomically Precise Cluster–Nanofiber Composites
A new methodology has been demonstrated
for ultratrace detection
of Hg<sup>2+</sup>, working at the limit of a few tens of metal ions.
Bright, red luminescent atomically precise gold clusters, Au@BSA (BSA,
bovine serum albumin), coated on Nylon-6 nanofibers were used for
these measurements. A green emitting fluorophore, FITC (fluorescein
isothiocyanate), whose luminescence is insensitive to Hg<sup>2+</sup> was precoated on the fiber. Exposure to mercury quenched the red
emission completely, and the green emission of the fiber appeared
which was observed under dark field fluorescence microscopy. For the
sensing experiment at the limit of sensitivity, we have used individual
nanofibers. Quenching due to Hg<sup>2+</sup> ions was fast and uniform.
Adaptation of such sensors to pH paper-like test-strips would make
affordable water quality sensors at ultralow concentrations a reality
Electrohydrodynamic Assembly of Ambient Ion-Derived Nanoparticles to Nanosheets at Liquid Surfaces
We describe an ambient
ion-based method to create free-standing
metal nanosheets, which in turn are composed of nanoparticles of the
corresponding metal. These nanoparticle-nanosheets (NP-NSs) were formed
by the electrospray deposition (ESD) of metal ions on a liquid–air
interface leading to nanoparticles that self-organize under the influence
of electrohydrodynamic flows, driven by the electric field induced
by the applied potential. Such a two-dimensional organization of noble
metals is similar to the assembly of molecules at liquid–air
interface and has the possibility of creating a category of new materials
useful for diverse applications. Enhanced catalytic activity of the
formed NP-NSs for Suzuki–Miyaura coupling reaction was demonstrated,
which was attributed to their large surface-to-volume ratios
Organic Solvent-Free Fabrication of Durable and Multifunctional Superhydrophobic Paper from Waterborne Fluorinated Cellulose Nanofiber Building Blocks
Gold-Induced Unfolding of Lysozyme: Toward the Formation of Luminescent Clusters
Ion mobility mass
spectrometry studies on Au<sub><i>n</i></sub>-Lyz adducts
showed gradual unfolding of the protein structure
during binding of Au<sup>+</sup> to the protein. The change of the
charge state envelope in Au<sub><i>n</i></sub>-Lyz from
that of Lyz in ESI MS data confirmed the relaxation of the protein
structure. This Au<sup>+</sup> binding occurs at cysteine sites through
the breakage of disulfide bonds and this ruptures the H-bonded folded
network structure of the protein leading to ∼30% change in
helicity. Nearly 15% loss in the total H-bonding occurred during the
attachment of 8 Au to the protein as calculated by a molecular dynamics
simulation. Different Au<sub><i>n</i></sub>-Lyz structures
were simulated, which confirmed significant unfolding of the protein.
The structural insights were used to understand similar unfolding
in the solution state as seen via circular dichroism (CD) and Fourier
transform infrared (FTIR) spectroscopy. This open structure is indeed
necessary to accommodate a cluster core inside a protein cavity during
luminescent cluster synthesis. These studies unambiguously establish
noble metal binding-induced conformational changes of protein structures
to accommodate the clusters