3 research outputs found
Self-Assembled Peptide Hydrogel as a Smart Biointerface for Enzyme-Based Electrochemical Biosensing and Cell Monitoring
A self-assembled
peptide nanofibrous hydrogel composed of <i>N</i>-fluorenylmethoxycarbonyl-diphenylalanine
(Fmoc-FF) was used to construct a smart biointerface. This biointerface
was then used for enzyme-based electrochemical biosensing and cell
monitoring. The Fmoc-FF hydrogel had two functions. One was as a matrix
to embed an enzyme model, horseradish peroxidase (HRP), during the
self-assembly of Fmoc-FF peptides. The other was use as a robust substrate
for cell adhesion. Experimental data demonstrated that HRP was immobilized
in a stable manner within the peptide hydrogel, and that HRP retained
its inherent bioactivity toward H<sub>2</sub>O<sub>2</sub>. The HRP
also can realize direct electron transfer in the Fmoc-FF hydrogel.
The resulting third-generation electrochemical H<sub>2</sub>O<sub>2</sub> biosensor exhibited good analytical performance, including
a low limit of detection of 18 nM, satisfactory reproducibility, and
high stability and selectivity. HeLa cells were then adhered to the
HRP/Fmoc-FF hydrogel-modified electrode. The sensitive in situ monitoring
of H<sub>2</sub>O<sub>2</sub> released from HeLa cells was realized.
This biointerface based on the Fmoc-FF hydrogel was easily prepared,
environmentally friendly, and also versatile for integration of other
cells and recognized molecules for the monitoring of various
cellular biomolecules. The smart biointerface has potential application
in broad physiological and pathological investigations
Assembly of Ruthenium-Based Complex into Metal–Organic Framework with Tunable Area-Selected Luminescence and Enhanced Photon-to-Electron Conversion Efficiency
Host–guest photofunctional
materials have received much
attention recently due to their potential applications in light emitting
diodes, polarized emission, and other optoelectronic fields. In this
work, we report the encapsulation of a photoactive ruthenium-based
complex (4,4′-diphosphonate-2,2′-bipyridine) into the
biphenyl-based metal–organic framework (MOF) as a host–guest
material toward potential photofunctional applications. The resulting
material (denoted as Ru@MOF) presents different two-color blue/red
luminescences at the crystal interior and exterior as detected by
three-dimensional confocal fluorescence microscopy. Additionally,
up-conversion emission and an enhanced photoluminescence lifetime
relative to the pristine Ru-based complex can also be observed in
this Ru@MOF system. Upon attaching on the rutile TiO<sub>2</sub> nanoarray,
the Ru@MOF also exhibits alternated photoelectrochemical properties
relative to the pristine complex. Moreover, a density functional theoretical
calculation was performed on the Ru@MOF structure to provide understanding
of the host–guest interactions. Based on the combination of
experimental and theoretical studies on the Ru@MOF system, the aim
of this work is to deeply investigate how the host–guest materials
can present different photofunctionalities and optoelectronic properties
compared with those of the individual components, and to give detailed
information on the potential host–guest energy/electronic transfer
between the MOF and the complex
Single-Crystalline Organic–Inorganic Layered Cobalt Hydroxide Nanofibers: Facile Synthesis, Characterization, and Reversible Water-Induced Structural Conversion
New pink organic–inorganic
layered cobalt hydroxide nanofibers
intercalated with benzoate ions [CoÂ(OH)Â(C<sub>6</sub>H<sub>5</sub>COO)·H<sub>2</sub>O] have been synthesized by using cobalt nitrate and sodium benzoate as
reactants in water with no addition of organic solvent or surfactant.
The high-purity nanofibers are single-crystalline in nature and very
uniform in size with a diameter of about 100 nm and variable lengths
over a wide range from 200 ÎĽm down to 2 ÎĽm by simply adjusting
reactant concentrations. The as-synthesized products are well-characterized
by scanning electron microscope (SEM), transmission electron microscopy
(TEM), high-resolution transmission electron microscopy (HRTEM), fast
Fourier transforms (FFT), X-ray diffraction (XRD), energy dispersive
X-ray spectra (EDX), X-ray photoelectron spectra (XPS), elemental
analysis (EA), Fourier transform infrared (FT-IR), thermogravimetric
analysis (TGA), and UV–vis diffuse reflectance spectra (UV–vis).
Our results demonstrate that the structure consists of octahedral
cobalt layers and the benzoate anions, which are arranged in a bilayer
due to the π–π stacking of small aromatics. The
carboxylate groups of benzoate anions are coordinated to Co<sup>II</sup> ions in a strong bridging mode, which is the driving force for the
anisotropic growth of nanofibers. When NaOH is added during the synthesis,
green irregular shaped platelets are obtained, in which the carboxylate
groups of benzoate anions are coordinated to the Co<sup>II</sup> ions
in a unidentate fashion. Interestingly, the nanofibers exhibit a reversible
transformation of the coordination geometry of the Co<sup>II</sup> ions between octahedral and pseudotetrahedral with a concomitant
color change between pink and blue, which involves the loss and reuptake
of unusual weakly coordinated water molecules without destroying the
structure. This work offers a facile, cost-effective, and green strategy
to rationally design and synthesize functional nanomaterials for future
applications in catalysis, magnetism, gas storage or separation, and
sensing technology