Long-distance propagation of high-velocity antiferromagnetic spin waves

We report on coherent propagation of antiferromagnetic (AFM) spin waves over a long distance ($\sim$10 $\mu$m) at room temperature in a canted AFM $\alpha$-Fe$_2$O$_3$ with the Dzyaloshinskii-Moriya interaction (DMI). Unprecedented high group velocities (up to 22.5 km/s) are characterized by microwave transmission using all-electrical spin wave spectroscopy. We derive analytically AFM spin-wave dispersion in the presence of the DMI which accounts for our experimental results. The AFM spin waves excited by nanometric coplanar waveguides with large wavevectors enter the exchange regime and follow a quasi-linear dispersion relation. Fitting of experimental data with our theoretical model yields an AFM exchange stiffness length of 1.7 angstrom. Our results provide key insights on AFM spin dynamics and demonstrate high-speed functionality for AFM magnonics

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Facile fabrication of varisized calcium carbonate microspheres as vaccine adjuvants

Functional calcium carbonate (CaCO3) particles of micron and submicron sizes used in catalysis and biomedicine have attracted considerable attention for decades. In this paper, the process parameters for CaCO3 crystallization were systematically investigated. Our experimental results demonstrated the significance of temperature during fabrication. Under the optimized conditions, various uniform-sized and spherical CaCO3 microparticles (MPs) with average diameters from 0.8 mm to 5 mm were facilely and rapidly fabricated via different mixing strategies including mechanical stirring, homogenization, and ultrasonication. The physicochemical characteristics of the CaCO3 microspheres were evaluated. And, the hepatitis B surface antigen (HBsAg) used as a model antigen was encapsulated into the particles (1 mm and 4 mm) for investigating the immune responses elicited after vaccination. In vitro, dendritic cells (DCs) were significantly activated by the MP-based vaccine formulations with up-regulated co-stimulatory molecules expression of CD40 and CD83. After immunization, CaCO3 MPs loaded with HBsAg induced greater lymphocyte activation, more cytokine secretion, higher antigen-specific IgG titers and more memory T cell generation to protect against reinfection. Therefore, the CaCO3 MPs, especially the 1 mm particles, could induce strong cellular and humoral immune responses, probably because of easier uptake and more efficient antigen-presentation by DCs. With the advantages of good biocompatibility, high loading capacity and easy preparation, they could be potentially useful as vaccine adjuvants. These results might provide further design principles for potent inorganic particulate adjuvant and delivery systems.</p

Potential Hepatitis B Vaccine Formulation Prepared by Uniform-Sized Lipid Hybrid PLA Microparticles with Adsorbed Hepatitis B Surface Antigen

For the purpose of strengthening the immunogenicity of the hepatitis B vaccine, which contains hepatitis B surface antigen (HBsAg), the development of biodegradable poly(lactic acid) (PLA) microparticles (MPs) modified with the cationic surfactant didodecyldimethylammonium bromide (DDAB) was attempted. DDAB-PLA MPs with an uniform size of about 1 mu m were prepared in a simple and mild way. DDAB-PLA MPs with increased surface charge enhanced antigen adsorption capacity compared to plain PLA MPs. After immunization, DDAB-PLA MPs induced the gene expression of inflammatory cytokines and chemokines, which facilitated the following immune responses. DDAB-PLA MPs augmented the expression of co-stimulatory molecules along with the activation of bone-marrow-derived dendritic cells (BMDCs). DDAB-PLA MP-based vaccine formulations efficiently induced antibody production more than the aluminum-based vaccine and plain PLA MP-based formulation in vivo. Moreover, DDAB-PLA MPs were more likely to generate the polarization of the Th1 response indicating the cytotoxic ability against infectious pathogens. In conclusion, DDAB-PLA MPs could be a potent vaccine formulation to prime robust cellular and humoral immune responses

Adjuvanticity Regulation by Biodegradable Polymeric Nano/microparticle Size

Polymeric nano/microparticles as vaccine adjuvants have been researched in experimental and clinical studies. A more profound understanding of how the physicochemical properties regulate specific immune responses has become a vital requirement. Here we prepared poly(D,Llactic-co-glycolic acid) (PLGA) nano/microparticles with uniform sizes (500 nm, 900 nm, 2.1 mu m, and 4.9 mu m), and the size effects on particle uptake, activation of macrophages, and antigen internalization were evaluated. Particle uptake kinetic studies demonstrated that 900 nm particles were the easiest to accumulate in cells. Moreover, they could induce macrophages to secrete NO and IL-1 beta and facilitate antigen internalization. Furthermore, 900 nm particles, mixed with antigen, could exhibit superior adjuvanticity in both humoral and cellular immune responses in vivo, including offering the highest antibody protection, promoting the maximum secretion levels of IFN-gamma and IL-4 than particles with other sizes. Overall, 900 nm might be the optimum choice for PLGA particle-based vaccine adjuvants especially for recombinant antigens. Understanding the effect of particle size on the adjuvanticity based immune responses might have important enlightenments for rational vaccine design and applications.</p

Pathogen-Mimicking Polymeric Nanoparticles based on Dopamine Polymerization as Vaccines Adjuvants Induce Robust Humoral and Cellular Immune Responses

Aiming to enhance the immunogenicity of subunit vaccines, a novel antigen delivery and adjuvant system based on dopamine polymerization on the surface of poly(d,l-lactic-glycolic-acid) nanoparticles (NPs) with multiple mechanisms of immunity enhancement is developed. The mussel-inspired biomimetic polydopamine (pD) not only serves as a coating to NPs but also functionalizes NP surfaces. The method is facile and mild including simple incubation of the preformed NPs in the weak alkaline dopamine solution, and incorporation of hepatitis B surface antigen and TLR9 agonist unmethylated cytosine-guanine (CpG) motif with the pD surface. The as-constructed NPs possess pathogen-mimicking manners owing to their size, shape, and surface molecular immune-activating properties given by CpG. The biocompatibility and biosafety of these pathogen-mimicking NPs are confirmed using bone marrow-derived dendritic cells. Pathogen-mimicking NPs hold great potential as vaccine delivery and adjuvant system due to their ability to: 1) enhance cytokine secretion and immune cell recruitment at the injection site; 2) significantly activate and maturate dendritic cells; 3) induce stronger humoral and cellular immune responses in vivo. Furthermore, this simple and versatile dopamine polymerization method can be applicable to endow NPs with characteristics to mimic pathogen structure and function, and manipulate NPs for the generation of efficacious vaccine adjuvants