Rapid development of SARS-CoV-2 receptor binding domain-conjugated nanoparticle vaccine candidate

The ongoing of coronavirus disease 2019 (COVID-19) pandemic caused by novel SARS-CoV-2 coronavirus, resulting in economic losses and seriously threating the human health in worldwide, highlighting the urgent need of a stabilized, easily produced and effective preventive vaccine. The SARS-COV-2 spike protein receptor binding region (RBD) plays an important role in the process of viral binding receptor angiotensin-converting enzyme 2 (ACE2) and membrane fusion, making it an ideal target for vaccine development. In this study, we designed three different RBD-conjugated nanoparticles vaccine candidates, RBD-Ferritin (24-mer), RBD-mi3 (60-mer) and RBD-I53-50 (120-mer), with the application of covalent bond linking by SpyTag-SpyCatcher system. It was demonstrated that the neutralizing capability of sera from mice immunized with three RBD-conjugated nanoparticles adjuvanted with AddaVax or Sigma Systerm Adjuvant (SAS) after each immunization was ~8-to 120-fold greater than monomeric RBD group in SARS-CoV-2 pseudovirus and authentic virus neutralization assay. Most importantly, sera from RBD-conjugated NPs groups more efficiently blocked the binding of RBD to ACE2 or neutralizing antibody in vitro, a further proof of promising immunization effect. Besides, high physical stability and flexibility in assembly consolidated the benefit for rapid scale-up production of vaccine. These results supported that our designed SARS-CoV-2 RBD-conjugated nanoparticle was competitive vaccine candidate and the carrier nanoparticles could be adopted as universal platform for future vaccine development.

Controllable degradation of medical magnesium by electrodeposited composite films of mussel adhesive protein (Mefp-1) and chitosan.

To control the degradation rate of medical magnesium in body fluid environment, biocompatible films composed of Mussel Adhesive Protein (Mefp-1) and chitosan were electrodeposited on magnesium surface in cathodic constant current mode. The compositions and structures of the films were characterized by atomic force microscope (AFM), scanning electron microscope (SEM) and infrared reflection absorption spectroscopy (IRAS). And the corrosion protection performance was investigated using electrochemical measurements and immersion tests in simulated body fluid (Hanks' solution). The results revealed that Mefp-1 and chitosan successfully adhered on the magnesium surface and formed a protective film. Compared with either single Mefp-1 or single chitosan film, the composite film of chitosan/Mefp-1/chitosan (CPC (chitosan/Mefp-1/chitosan)) exhibited lower corrosion current density, higher polarization resistance and more homogenous corrosion morphology and thus was able to effectively control the degradation rate of magnesium in simulated body environment. In addition, the active attachment and spreading of MC3T3-E1 cells on the CPC film coated magnesium indicated that the CPC film was significantly able to improve the biocompatibility of the medical magnesium.

Teratogenicity of 3, 4 two furazan-based oxidation furazan in rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the teratogenicity of new high-energy compounds, 3, 4 two furazan-based oxidation furazan (DNTF) and the impact on human health, occupational exposure limits were provided for the following research.</p><p><b>METHODS</b>Pregnant SD rats were randomly divided into five groups by Standard teratogenicity test, including three dose groups (5.0, 15.8, 50.0 mg/kg), the negative control (vegetable oil), and the positive control group (CP 10.0 mg/kg). Each 10 to 15 rats were in one group. Gavage was consecutive for rats during pregnancy 7 ∼ 12 d and then sacrifice after 20 d.</p><p><b>RESULTS</b>There were no significantly difference between the three dose groups and negative controls in the pregnancy rate, the weight of pregnant rats, fetal weight, fetal growth, fetal malformation rate and internal organs,</p><p><b>CONCLUSION</b>There were no maternal toxicity, embryo toxicity and teratogenicity for rats when DNTF in the range 5.0 ∼ 50.0 mg/kg.</p>