Reusable and pH-Stable Luminescent Sensors for Highly Selective Detection of Phosphate

Phosphate sensors have been actively studied owing to their importance in water environment monitoring because phosphate is one of the nutrients that result in algal blooms. As with other nutrients, seamless monitoring of phosphate is important for understanding and evaluating eutrophication. However, field-deployable phosphate sensors have not been well developed yet due to the chemical characteristics of phosphate. In this paper, we report on a luminescent coordination polymer particle (CPP) that can respond selectively and sensitively to a phosphate ion against other ions in an aquatic ecosystem. The CPPs with an average size of 88.1 ± 12.2 nm are embedded into membranes for reusable purpose. Due to the specific binding of phosphates to europium ions, the luminescence quenching behavior of CPPs embedded into membranes shows a linear relationship with phosphate concentrations (3–500 μM) and detection limit of 1.52 μM. Consistent luminescence signals were also observed during repeated measurements in the pH range of 3–10. Moreover, the practical application was confirmed by sensing phosphate in actual environmental samples such as tap water and lake water.

New progress in international nanotechnology research in the past ten years – visual analysis based on CitesSpace

With the continuous development of high-tech industry, Moore’s law is close to the limit. People urgently need nano science and technology to trigger a new scientific and technological revolution to meet the needs of life, military and so on. Nanotechnology covers almost all industries and has made achievements in the industries such as medical, materials, manufacturing, and information technology. It has changed the production and life of human beings and subverted many industries. In recent years, more and more people have conducted data mining on nanotechnology research. By combing the literature, this paper summarizes the core authors, keyword changes, important authors and emergent words of the existing literature. Contributing to analyzing the research status of this field and revealing research hotspots in this field. It is of great significance for scholars to sort out the development process of nano field and predict the future development trend. Using CitesSpace bibliometric analysis software, 44002 pieces of literature about nanotechnology in SCI and SSCI journals in the core collection of the Web of Science database were analyzed in this paper. The results indicated that countries such as the United States, Germany, China, and Japan have issued more articles; However, the centrality of articles published in European countries such as the UK, Germany, and France was relatively strong; High-yield units mainly included Chinese Acad Sci and Russian Acad Sci; The main research scholars were Wei Wang, Peixuan Guo, Thomas J Webster, Hao Yan; Research emergent words primarily included polymer, particle, dynamics, mechanical properties and silver nanoparticle. On this basis, countermeasure suggestions and prospects are proposed.

Engineering Antigens to Assemble into Polymer Particle Vaccines for Prevention of Streptococcus suis Infection

Streptococcus suis is a zoonotic pathogen affecting pigs and humans. This bacterium causes severe economic losses in the swine industry and poses a serious threat to public health and food safety. There is no effective commercial vaccine available for pigs or humans. In this study, we applied the biopolymer particle (BP) vaccine technology to incorporate seven conserved S. suis antigens (38 kDa protein (38), enolase (Enol), SSU1915, SSU1355, SSU0185, SSU1215, and SSU1773 (SSU1 and SSU2)). Two combinations of these antigens (38 and Enol; all SSU antigens designated as SSU1 and SSU2) were engineered to mediate production of BPs coated with either antigens 38 and Enol or SSU1 and SSU2 inside recombinant Escherichia coli. The isolated and purified empty BPs, 38-BP-Enol and SSU1-BP-SSU2, showed size ranges of 312–428 nm and 292–344 nm with and without the QuilA® adjuvant, respectively, and all showed a negative surface charge. Further characterization of purified BPs confirmed the presence of the expected antigen-comprising fusion proteins as assessed by tryptic peptide fingerprinting analysis using quadrupole time-of-flight mass spectrometry and immunoblotting. Vaccination with 38-BP-Enol and SSU1-BP-SSU2 formulated with and without QuilA® adjuvant induced significant antigen-specific humoral immune responses in mice. Antigen-coated BPs induced significant and specific Ig (IgM + IgG) and IgG immune responses (1.0 × 106–1.0 × 107) when compared with mice vaccinated with empty BPs. Functionality of the immune response was confirmed in challenge experiments using an acute murine S. suis infection model, which showed 100% survival of the 38-BP-Enol and SSU1-BP-SSU2 vaccinated mice compared to 70% survival when vaccinated with empty BPs. Overall, our data suggest that S. suis antigen-coated BPs could be developed into particulate vaccines that induce protective immunity against S. suis infections.

Synthesis and Characterization of Novel Succinyl Chitosan-Dexamethasone Conjugates for Potential Intravitreal Dexamethasone Delivery

The development of intravitreal glucocorticoid delivery systems is a current global challenge for the treatment of inflammatory diseases of the posterior segment of the eye. The main advantages of these systems are that they can overcome anatomical and physiological ophthalmic barriers and increase local bioavailability while prolonging and controlling drug release over several months to improve the safety and effectiveness of glucocorticoid therapy. One approach to the development of optimal delivery systems for intravitreal injections is the conjugation of low-molecular-weight drugs with natural polymers to prevent their rapid elimination and provide targeted and controlled release. This study focuses on the development of a procedure for a two-step synthesis of dexamethasone (DEX) conjugates based on the natural polysaccharide chitosan (CS). We first used carbodiimide chemistry to conjugate DEX to CS via a succinyl linker, and we then modified the obtained systems with succinic anhydride to impart a negative ζ-potential to the polymer particle surface. The resulting polysaccharide carriers had a degree of substitution with DEX moieties of 2–4%, a DEX content of 50–85 μg/mg, and a degree of succinylation of 64–68%. The size of the obtained particles was 400–1100 nm, and the z-potential was −30 to −33 mV. In vitro release studies at pH 7.4 showed slow hydrolysis of the amide and ester bonds in the synthesized systems, with a total release of 8–10% for both DEX and succinyl dexamethasone (SucDEX) after 1 month. The developed conjugates showed a significant anti-inflammatory effect in TNFα-induced and LPS-induced inflammation models, suppressing CD54 expression in THP-1 cells by 2- and 4-fold, respectively. Thus, these novel succinyl chitosan-dexamethasone (SucCS-DEX) conjugates are promising ophthalmic carriers for intravitreal delivery.

Rigid Amorphous Fraction as an Indicator for Polymer-Polymer Interactions in Highly Filled Plastics

Above a percolation threshold a flow restriction has to be overcome by higher pressure in plastic processing. Besides amount and geometry of fillers, the interactions of polymer and filler are important. By differing the amorphous phase of polymers into a rigid amorphous and a mobile amorphous fraction, predictions about interactions are possible. The objective is the generation of a flow restriction and the combined investigation of polymer–particle interaction. SiO2 was used up to 50 vol.% in different spherical sizes in PLA and PP. A capillary-rheometer was used as a tool to create a yield point and by that investigations into the state of the flow restriction were possible. All produced compounds showed, in plate-plate rheometry, an increase in viscosity for lower shear rates and a significant change in the storage modulus. In DSC, hardly any specific rigid amorphous fraction was detectable, which suggests that there is a minor interaction between macromolecules and filler. This leads to the conclusion that the change in flow behavior is mainly caused by a direct interaction between the particles, even though they are theoretically too far away from each other. First images in the state of the yield point show a displacement of the particles against each other.

MANUFACTURING METHOD OF THE MORPHING WING STRUCTURE FOR UAV BY CFRP WITH APPLYING THE ELECTROFORMED RESIN MOLDING METHOD

Aircraft flight control usually requires driving flaps and ailerons. However, the air drags increase significantly due to the corners of flaps and aileron. Especially, the gap between mother wing and flap / aileron causes a drag increase. Therefore, studies are being conducted on morphing wings that smoothly and greatly deform the wing surface. For aircraft wing, it is needless to say that strength is important to sustain lift and drag for the aircraft during the flight. For morphing wings, in addition, actuators must be mounted inside the wing to enable the morphing deformation. Moreover, for the aircraft wing, weight is quite important. Therefore, carbon fiber reinforced plastic (CFRP) is currently most suitable for aircraft wing structural materials. However, it is difficult to mold CFRP so that it has sufficient strength and can be morphed. In this study, by using CFRP, the morphing wing structure was prototyped with targeting a small unmanned aerial vehicle (UAV) weighing 3 kg. The CFRP lattice structure that enables morphing deformation was designed and manufactured by applying the electrodeposition resin molding (ERM) method which was developed by the authors. In the ERM method, firstly, the carbon fiber was fixed with a jig according to the designed morphing wing structure, and immersed in the electrodeposition solution. Secondly, the epoxy polymer particle in the solution were electrophoresed and impregnated between carbon fibers. After thermal curing, the morphing wing structure was fabricated. Further, the loading-unloading torsion and bending tests of the morphing wing structure were carried out. Smooth morphing deformation and sufficient strength were confirmed.