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 45°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-poly­(ε-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 “swelling-broken”, “dissociating-broken”, and “bursting-broken” 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 Fe₃O₄/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 bullfrog’s 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 Parkinson’s 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 Parkinson’s disease and other related disorders

Colloidal CdSe 0‑Dimension Nanocrystals and Their Self-Assembled 2‑Dimension 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 ∼426 and ∼453 nm for amine ligand passivation and at ∼432 and ∼460 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