Search

γ-Polyglutamic acid is a kind of biomaterial and environmentally friendly polymer material with the characteristics of water solubility and good biocompatibility. It has a wide range of applications in medicine, food, cosmetics and other fields. This article reviews the preparation, characterization and medical applications of γ-polyglutamic acid nanoparticles. Nanoparticles prepared by using γ- polyglutamic acid not only had the traditional advantages of enhancing drug stability and slow-release effect, but also were simple to prepare without any biological toxicity. The current methods of nanoparticle preparation mainly include the ion gel method and solvent exchange method, which use the total electrostatic force, van der Waals force, hydrophobic interaction force and hydrogen bond force between molecules to embed materials with different characteristics. At present, there are more and more studies on the use of γ-polyglutamic acid to encapsulate drugs, and the research on the mechanism of its encapsulation and sustained release has gradually matured. The development and application of polyglutamic acid nanoparticles have broad prospects., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Antiviral agents based on natural products have attracted substantial attention in clinical applications for their distinct biological activities,molecular structuralmultiformities, and low biotoxicities. Ferulic acid (FA) with apigenin propaneto form an esterified FA derivative (FAAP).Herein, we designed a CsPbBr3-modified chitosan oligosaccharide, a biomimetic nanoplatform that could load with FAAP. After self-assembly by combining FAAP with CsPbBr3-modified chitosan oligosaccharide (FAAP NPs), the resulting nanoparticles (FAAP NPs) showed high antioxidant and anti-inflammatory activities for enhancing the inhibition of porcineparvovirus.FAAP NPs exhibited no signs of acute toxicity in vitro or in vivo. DPPH and ABST are widely used for quantitative determination of antioxidant capacity. FAAP NPs exhibited excellent DPPH and ABTS radical scavenging abilities. In addition, we found that FAAP NPs inhibited PPV infection-induced PK-15 cell apoptosis, which was associated with regulating antioxidant and anti-inflammatory signaling pathways. Importantly, we showed that FAAP NPs blocked PPV infection-induced mitochondrial apoptosis in PK-15 cells via a p53/BH3 domain molecular-dependent mechanism., (Copyright © 2021. Published by Elsevier B.V.)

Nanodiamonds (NDs), which are safe carbon nanomaterials, have been used for the transmission of DNA, proteins and drugs. The feasibility of utilizing NDs to deliver NH 2 -PLGA nanoparticle-encapsulated fig polysaccharides for strongly enhanced immune responses has not been clearly studied. In this study, we aimed to use NDs as carriers to deliver NH 2 -PLGA nanoparticle-encapsulated fig polysaccharides for strongly enhanced immune responses. ND particles with a diameter of 5 nm were functionalized by surface carboxylation and covalently conjugated with NH 2 -PLGA nanoparticle-encapsulated fig polysaccharides. NDs-PLGA-FP/OVA could promote antigen uptake and lymphocyte proliferation, increase the expression levels of MHC II, CD80 and CD86, and upregulate the ratio of Th1/Th2 cells in immunized mice. NDs-PLGA-FP/OVA could also upregulate the IL-17 signalling pathway for further immunological enhancement. NDs-PLGA-FP/OVA induced increased TNF-α, IFN-γ, IL-4, and IL-6 cytokine secretion and the levels of OVA-specific antibodies (IgG). These findings demonstrate that NDs-PLGA-FP/OVA have the potential to serve as an effective vaccine delivery and adjuvant system to induce vigorous and long-term immune responses., (Copyright © 2020. Published by Elsevier B.V.)

Recently, nanoparticles have been widely used in drug and vaccine adjuvant delivery. Dendrobium devonianum Polygonatum (DP), a main biologically active ingredient isolated from Dendrobium devonianum, has been widely used in the clinic as an immunostimulant to stimulate and improve immune responses, contributing to its excellent biological activity. To increase the immune efficacy of DP, macrophage cell membrane-coated drug nanocrystals featuring homologous immune escape, targeting ability and low toxicity are in high demand. In this study, a new drug and vaccine adjuvant delivery system, PEI-MM-PLGA-DP/OVA, was designed and developed. This study aimed to report the macrophage immunomodulatory activity of PEI-modified macrophage cell membrane-coated PLGA nanoparticles encapsulating Dendrobium devonianum polysaccharides. PEI-MM-PLGA-DP/OVA could promote antigen uptake by macrophage and lymphocyte proliferation, increase the expression levels of MHC II, CD80 and CD86, and upregulate the ratio of CD4 + to CD8 + T cells in immunized mice. PEI-MM-PLGA-DP/OVA induced the highest TNF-α, IFN-γ, IL-4, and IL-6 cytokine secretion levels and the levels of OVA-specific antibodies (IgG) compared with the other groups. The above results indicated that PEI-MM-PLGA-DP/OVA had better adjuvant activity than PLGA-DP/OVA and MM-PLGA-DP/OVA., (Copyright © 2020. Published by Elsevier B.V.)

CO2 electroreduction into liquid fuels is of broad interest and benefits reducing the energy crisis and environment burdens. CuS has been reported to be a desirable candidate for CO2 electroreduction into formate; however, its formate selectivity and stability are still far from the demands of practical application. Herein, we report CuS nanoparticles exhibiting good Faradaic efficiency of formate (about 98 %) in CO2 electroreduction and its deactivation mechanism during the reaction. The deactivation of CuS was found to be associated with the reconstruction and S loss of CuS, which deteriorates the Faradaic efficiency of formate. Combined with ionic and gas analyses, the S atom in CuS was lost in the form of H2S, SO2, and SO42−, followed by the reconstruction of CuS into copper oxides. Such a catalyst reconstruction facilitates electroreductions of CO2 and H2O, respectively, into CO and H2, etc., resulting in the degradation of catalytical performance of CO2 electroreduction into formate. This work reveals the important role of S loss and reconstruction of metal sulfide catalysts during the electroreduction reaction, which may benefit the further development of CuS‐based electro‐catalyst for CO2 electroreduction. [ABSTRACT FROM AUTHOR]

The maximum FE HCOOH acquired on Bi/CN is about 98%, and kept over 91% in a wide potential window. ga1. [Display omitted] It is still a great challenge to develop electrocatalysts for CO 2 reduction with high product selectivity and energy conversion efficiency. In this work, Bi nanoparticles supported on polymeric carbon nitride (Bi/CN) have been prepared for CO 2 electrocatalytic conversion. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses confirm the existence of Bi 2 O 3 on Bi particle surface, forming Bi/Bi 2 O 3 nanoparticles. CN, as the support, has been found not only to improve the dispersibility of Bi/Bi 2 O 3 nanoparticles, but also to enhance the CO 2 adsorption on Bi/CN surface owing to the existence of amino and cyano groups. The electronic structure of Bi/CN has been optimized by the interaction between CN and Bi: the electron transfer from Bi to CN results in electron-deficient Bi sites which stabilize CO 2 –, HCOO– intermediates and accelerate the formation rate of HCOOH. As a result, the maximum Faradaic efficiency of HCOOH reaches 98% at −1.3 to −1.5 V versus reversible hydrogen electrode (vs. RHE) and remains over 91% in a wide potential window of about 500 mV (-1.1 ∼ -1.6 V vs. RHE). The as-obtained Bi/CN in this work shows superior performance to most of the previously reported Bi-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Generally, metal matrix composites with homogenous microstructure exhibit good performance in mechanical properties, however, the shortcomings of limited strengthening effect by homogenous distributed reinforcements have been shown up in recent studies. In this work, the effect of reinforcement particles' hierarchical structure with bimodal distribution and nano-network on tensile properties of the AlN p /Al composites has been studied. A novel AlN p /Al composite with hierarchical structure has been fabricated using the in-situ liquid-solid reaction and hot extrusion, in order to further improve the mechanical properties. Furthermore, the AlN p /Al composite was processed by rotary swaging (RS) to obtain a more uniform structure. The results show that the AlN p /Al composites with hierarchical microstructure exhibit a superior ultimate tensile strength of ~410 MPa with uniform elongation of ~9.7%. However, the ultimate tensile strength and ductility of the AlN p /Al composite after swaging treatment decrease to 370 MPa and 6.7%, respectively. It can be concluded that the hierarchical structure has a distinct superiority in simultaneously improving the strength and ductility of the Al based composite over the homogenous structure. Furthermore, the strengthening and toughening mechanisms have been discussed as well. [ABSTRACT FROM AUTHOR]

Heterogeneous strengthening effect has been a more and more attractive theory for designing metal matrix composites in recent years. In this paper, a new multiphase reinforced Al composite (Al 12 Mo+(Al,Zr,Si)+Al 2 O 3)/Al has been prepared through a multi–stage reaction of Al–10ZrO 2 –5MoSi 2 alloy on the basis of Al–10ZrO 2 , i.e. (ZrAl 3 +Al 2 O 3)/Al composite, by introducing MoSi 2. The strengthening phases, including micro–sized Al 12 Mo, sub–micron (Al,Zr,Si) and nano–sized Al 2 O 3 , are in–situ synthesized, performing attractive strengthening effect. The in–situ synthesized sub–micron (Al,Zr,Si) and nano–sized Al 2 O 3 particles exhibit a net–work distribution, while micron Al 12 Mo particles act as the node of particle network. Compared with Al–10ZrO 2 , the Al–10ZrO 2 –5MoSi 2 composite exhibits improved tensile strength at both room temperature (25 °C) and elevated temperature (350 °C). The reaction mechanism and phase evolution procedure have been discussed. This work can be referred in designing new multifarious particles reinforced composites to achieve promotion at material properties. [ABSTRACT FROM AUTHOR]