7 research outputs found
Extraction and composition characterisation of amino acids from tung meal
<p>The most desirable content of amino acids (AAs) in the extracted products from tung (<i>Aleurites fordii</i>) meal was 93.88%, which was obtained from shelled tung meal at a hydrolysis temperature of 45Ā°C and a isoelectric precipitation pH value of 4.4. Furthermore, the cytotoxic activity of extracted AAs was also evaluated by MTT assay. Antioxidant activity of extracted AAs was also measured by the DPPH assay. As a result, the high yield of extracted AAs exhibited so low cytotoxic and high antioxidant activity that had the potential use as a functional ingredient.</p
Shape Memory Actuation of Janus Nanoparticles with Amphipathic Cross-Linked Network
Preparation
of nanoscale Janus particles that can respond to external
stimulation and, at the same time, be prepared using an easily achievable
method presents a significant challenge. Here, we have demonstrated
the shape memory of Janus nanoparticles (SMJNPs) with a multifunctional
combination of Janus nanostructure and a shape memory effect, composed
of a well-defined amphipathic sucrose-polyĀ(Īµ-caprolactone) cross-linked
network. A sudden negative pressure method was first used to prepare
the Janus-shaped nanoparticles (temporary shape), which can switch
their shape and wettability. The Janus-shaped nanoparticle is an amphipathic
structure composed of hydrophilic and hydrophobic parts. Moreover,
in response to temperature, the nanoparticle can recover their nanosphere
state via a shape memory process. The novel Janus nanoparticles with
the shape memory property also show a great potential for application
such as drug delivery
Supercooling Self-Assembly of Magnetic Shelled Core/Shell Supraparticles
Molecular self-assembly
has emerged as a powerful technique for
controlling the structure and properties of core/shell structured
supraparticles. However, drug-loading capacities and therapeutic effects
of self-assembled magnetic core/shell nanocarriers with magnetic nanoparticles
in the core are limited by the intervention of the outer organic or
inorganic shell, the aggregation of superparamagnetic nanoparticles,
the narrowed inner cavity, etc. Here, we present a self-assembly approach
based on rebalancing hydrogen bonds between components under a supercooling
process to form a new core/shell nanoscale supraparticle with magnetic
nanoparticles as the shell and a polysaccharide as a core. Compared
with conventional iron oxide nanoparticles, this magnetic shelled
core/shell nanoparticle possesses an optimized inner cavity and a
loss-free outer magnetic property. Furthermore, we find that the drug-loaded
magnetic shelled nanocarriers showed interesting <i>in vitro</i> release behaviors at different pH conditions, including āswelling-brokenā,
ādissociating-brokenā, and ābursting-brokenā
modes. Our experiments demonstrate the novel design of the multifunctional
hybrid nanostructure and provide a considerable potential for the
biomedical applications
Self-Powered Nanocomposites under an External Rotating Magnetic Field for Noninvasive External Power Supply Electrical Stimulation
Electrical
stimulation in biology and gene expression has attracted
considerable attention in recent years. However, it is inconvenient
that the electric stimulation needs to be supplied an implanted power-transported
wire connecting the external power supply. Here, we fabricated a self-powered
composite nanofiber (CNF) and developed an electric generating system
to realize electrical stimulation based on the electromagnetic induction
effect under an external rotating magnetic field. The self-powered
CNFs generating an electric signal consist of modified MWNTs (m-MWNTs)
coated Fe<sub>3</sub>O<sub>4</sub>/PCL fibers. Moreover, the output
current of the nanocomposites can be increased due to the presence
of the magnetic nanoparticles during an external magnetic field is
applied. In this paper, these CNFs were employed to replace a bullfrogās
sciatic nerve and to realize the effective functional electrical stimulation.
The cytotoxicity assays and animal tests of the nanocomposites were
also used to evaluate the biocompatibility and tissue integration.
These results demonstrated that this self-powered CNF not only plays
a role as power source but also can act as an external power supply
under an external rotating magnetic field for noninvasive the replacement
of injured nerve
Isolation and Sequencing of Salsolinol Synthase, an Enzyme Catalyzing Salsolinol Biosynthesis
Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline),
a derivate of dopamine, is suspected to be the most probable neurotoxin
in the degeneration of dopaminergic neurons. Numerous hypotheses regarding
its pathophysiological roles have been raised, especially related
to Parkinsonās disease and alcohol addiction. In the mammalian
brain, salsolinol may be enzymatically synthesized by salsolinol synthase
from dopamine and acetaldehyde. However, the direct evidence of its
biosynthesis was still missing. In this study, we purified salsolinol
synthase from rat brain by a systematical procedure involving acid
precipitation, ultrafiltration, and hydrophilic interaction chromatography.
The molecular weight of salsolinol synthase determined by MALDI-TOF
MS is 8622.29 Da, comprising 77 amino acids (MQIFVKTLTG KTITLEVEPS
DTIKNVKAKI QDKEGIPPDQ QRLIFAGKQL EDGRTLSDYN IQKKSTLHLV LRLRVDY). Homology
analysis showed that the enzyme is a ubiquitin-like protein, with
a difference of four amino acids, which suggests it is a novel protein.
After it was overexpressed in eukaryotic cells, the production of
salsolinol was significantly increased as compared with control, confirming
the catalytic function of this enzyme. To our knowledge, it is the
first systematic purification and sequencing of salsolinol synthase.
Together, this work reveals a formerly anonymous protein and urges
further exploration of its possible prognostic value and implications
in Parkinsonās disease and other related disorders
Colloidal CdSe 0āDimension Nanocrystals and Their Self-Assembled 2āDimension Structures
We
report on a particular type of CdSe nanocrystals (NCs) that
exhibit a single optical absorption doublet. The two peaks in the
doublet are relatively sharp with a full width half-maximum as narrow
as 10 nm. The peak positions vary with passivation ligands (at ā¼426
and ā¼453 nm for amine ligand passivation and at ā¼432
and ā¼460 nm for carboxylate ligand passivation). To date, it
has been generally concluded that these NCs have a two-dimension (2D)
morphology with 1D quantum confinement. Here, we report that zero-dimension
(0D) NCs with 3D quantum confinement can exhibit a very similar static
optical feature consisting of a sharp absorption doublet. We show
that our as-prepared CdSe NCs (without further purification) were
mainly 0D NCs, as observed when they were deposited on transmission
electron microscopy (TEM) grids directly from toluene or hexane dispersions.
We further demonstrate that it was possible to alter this 0D morphology
by using dispersion additives and/or purification solvents to result
in the appearance of 2D NCs under TEM. Although the 0D and self-assembled
2D NCs displayed similar static optical features, the two morphologies
behaved quite differently in polarized emission. The 2D NCs exhibited
detection angle dependent polarized emission, whereas the 0D NCs do
not. Our findings indicate that a well-like morphology can be induced
by the presence of hexadecylamine (HDA) in the dispersion with sonication
for amine-passivated 0D NCs or by the use of ethanol during purification
with dispersion storage for carboxylate-passivated 0D NCs. In this
way, it is possible to manipulate the NC morphology for a targeted
application through the appropriate post-treatment. This study highlights
that more sophisticated theoretical studies are required to account
for the experimental observations in which both 0D NCs and their self-assembled
2D NC products display similar static optical features
Pulse Electrochemical Driven Rapid Layer-by-Layer Assembly of Polydopamine and Hydroxyapatite Nanofilms via Alternative Redox <i>in Situ</i> Synthesis for Bone Regeneration
Polydopamine (PDA) is an important
candidate material for the surface
modification of biomedical devices because of its good adhesiveness
and biocompatibility. However, PDA nanofilms lack osteoinductivity,
limiting their applications in bone tissue engineering. Hydroxyapatite
nanoparticles (HA-NPs) are the major component of natural bone, which
can be used to effectively enhance the osteoinductivity of PDA nanofilms.
Herein, we developed a pulse electrochemical driven layer-by-layer
(PED-LbL) assembly process to rapidly deposit HA-NPs and PDA (HA-PDA)
multilayer nanofilms. In this process, PDA and HA-NPs are <i>in situ</i> synthesized in two sequential oxidative and reductive
pulses in each electrochemical deposition cycle and alternately deposited
on the substrate surfaces. PDA assists the <i>in situ</i> synthesis of HA-NPs by working as a template, which avoids the noncontrollable
HA nucleation and aggregation. The HA-PDA multilayer nanofilms serve
as a tunable reservoir to deliver bone morphogenetic protein-2 and
exhibit high osteoinductivity both <i>in vitro</i> and <i>in vivo</i>. This PED-LbL assembly process breaks the limitation
of traditional LbL assembly, allowing not only the rapid assembly
of oppositely charged polyelectrolytes but also the <i>in situ</i> synthesis of organic/inorganic NPs that are uniformly incorporated
in the nanofilm. It has broad applications in the preparation of versatile
surface coatings on various biomedical devices