Simultaneous mass production of high quality vertically oriented graphene nanostructures and doping them by using an inductively coupled plasma chemical vapor deposition (ICP CVD) is a technological problem because little is understood about their growth mechanism over enlarged surfaces. We introduce a new method that combines the ICP CVD with roll-to-roll technology to enable the in-situ preparation of vertically oriented graphene by using propane as a precursor gas and nitrogen or silicon as dopants. This new technology enables preparation of vertically oriented graphene with distinct morphology and composition on a moving copper foil substrate at a lower cost. The technological parameters such as deposition time (1–30 min), gas partial pressure, composition of the gas mixture (propane, argon, nitrogen or silane), heating treatment (1–60 min) and temperature (350–500 °C) were varied to reveal the nanostructure growth, the evolution of its morphology and heteroatom’s intercalation by nitrogen or silicon. Unique nanostructures were examined by FE-SEM microscopy, Raman spectroscopy and energy dispersive X-Ray scattering techniques. The undoped and nitrogen- or silicon-doped nanostructures can be prepared with the full area coverage of the copper substrate on industrially manufactured surface defects. Longer deposition time (30 min, 450 °C) causes carbon amorphization and an increased fraction of sp3-hybridized carbon, leading to enlargement of vertically oriented carbonaceous nanostructures and growth of pillars.
A single-step ultrasonic
method (20 kHz) is demonstrated for the
formation of acetylsalicylic acid-Fe3O4-graphene
oxide nanocomposites (∼80 nm) in aqueous solution. The electronic
molecular structure of these nanocomposites is stable in acidic or
basic aqueous medium. Coating of these nanocomposites with poly(vinyl
alcohol) (PVA) occurs through increased binding with drug, magnetite,
Fe(II)–C–O and carbonaceous network of graphene oxide.
PVA-coated-acetylsalicylic acid-Fe3O4-GO nanocomposites
substantially improve acetylation of pristine ascorbic acid than free
unmodified drug or uncoated acetylsalicylic acid-Fe3O4-GO nanoparticles because of enhanced electron density through
the presence of magnetite and graphene oxide, and specific binding
of PVA with drug and ascorbic acid.
We
demonstrate a single-step ultrasonic in situ complexation of
salicylic acid during the growth of Fe3O4-reduced
graphene oxide nanoparticles (∼10 nm) to improve the antioxidant
and antiproliferative effects of pristine drug molecules. These nanoparticles
have a precisely defined electronic molecular structure with salicylic
acid ligands specifically complexed to Fe(III)/Fe(II) sites, four
orders of magnitude larger electric surface potential, and enzymatic
activity modulated by ascorbic acid molecules. The diminishing efficiency
of hydroxyl radicals by Fe3O4-rGO-SA nanoparticles
is tenfold higher than that by pristine salicylic acid in the electro-Fenton
process. The H+ production of these nanoparticles can be
switched by the interaction with ascorbic acid ligands and cause the
redox deactivation of iron or enhanced antioxidation, where rGO plays
an important role in enhanced charge transfer catalysis. Fe3O4-rGO-SA nanoparticles are nontoxic to erythrocytes,
i.e., human peripheral blood mononuclear cells, but surpassingly inhibit
the growth of three cancer cell lines, HeLa, HepG2, and HT29, with
respect to pristine salicylic acid molecules.
An ultrasonic method (20 kHz) is introduced to activate
pristine
ibuprofen organic molecular crystals via complexation with silver
in nitrogen-doped oxidized graphene nanoplatforms (∼50 nm).
Ultrasonic complexation occurs in a single-step procedure through
the binding of the carboxylic groups with Ag and H-bond formation,
involving noncovalent πC=C → πC=C* transitions in the altered phenyl ring and πPY →
πCO* in ibuprofen occurring between the phenyl ring
and C–O bonds as a result of interaction with hydroxyl radicals.
The ibuprofen–silver complex in ≪NrGO≫ exhibits
a ∼42 times higher acceleration rate than free ibuprofen of
the charge transfer between hexacyanoferrate and thiosulfate ions.
The increased acceleration rate can be caused by electron injection/ejection
at the interface of the ≪Ag-NrGO≫ nanoplatform and formation
of intermediate species (Fe(CN)5(CNSO3)
x− with x = 4 or 5
and AgHS2O3) at the excess of produced H+ ions. Important for microwave chemotherapy, ibuprofen–silver
complexes in the ≪NrGO≫ nanoplatform can produce H+ ions at ∼12.5 times higher rate at the applied voltage
range from 0.53 to 0.60 V. ≪Ibu-Ag-NrGO≫ NPs develop
∼105 order higher changes of the electric field
strength intensity than free ibuprofen in the microwave absorption
range of 100–1000 MHz as revealed from the theoretical modeling
of a cervix tumor tissue.
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