Search

In the present work, a nanoscale porous surface was gradually prepared on Ti surface by two-step method of acid corrosion and NaOH–H 2 O 2 mixing treatment. This led to the formation of a TiO2 coating at the surface of the underlying Ti substrate. Then, silver nanowires were deposited on the nanostructured surface by spin-coating technology. The nanowires were found to be evenly introduced into the nanostructured TiO2 coating. The modified Ti surface showed good wettability and protein adsorption capacity. More importantly, in-vitro cellular and bacterial assays indicated that the modified Ti surface possessed not only the excellent adhesion and differentiation abilities for osteoblasts but also relatively strong antimicrobial capacities for both S. aureus and E. coli. The results suggest that such modified Ti surfaces greatly prefer the initial adhesion of osteoblast-like cells over the initial adhesion of bacteria. The surface modification that we made to Ti substrate can promisingly meet clinical requirements. [ABSTRACT FROM AUTHOR]

Rice bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most serious diseases affecting rice production worldwide. Xa21 was the first disease resistance gene cloned in rice, which encodes a receptor kinase and confers broad resistance against Xoo stains. Dozens of components in the Xa21-mediated pathway have been identified in the past decades, however, the involvement of mitogen-activated protein kinase (MAPK) genes in the pathway has not been well described. To identify MAPK involved in Xa21-mediated resistance, the level of MAPK proteins was profiled using Western blot analysis. The abundance of OsMPK17 (MPK17) was found decreased during the rice-Xoo interaction in the background of Xa21. To investigate the function of MPK17, MPK17-RNAi and over-expression (OX) transgenic lines were generated. The RNAi lines showed an enhanced resistance, while OX lines had impaired resistance against Xoo, indicating that MPK17 plays negative role in Xa21-mediated resistance. Furthermore, the abundance of transcription factor WRKY62 and pathogenesis-related proteins PR1A were changed in the MPK17 transgenic lines when inoculated with Xoo. We also observed that the MPK17-RNAi and -OX rice plants showed altered agronomic traits, indicating that MPK17 also plays roles in the growth and development. On the basis of the current study and published results, we propose a "Xa21-MPK17-WRKY62-PR1A" signaling that functions in the Xa21-mediated disease resistance pathway. The identification of MPK17 advances our understanding of the mechanism underlying Xa21-mediated immunity, specifically in the mid- and late-stages. [ABSTRACT FROM AUTHOR]

Key message: OsMKK1, a MAPK gene, positively regulates rice Xa21-mediated resistance response and also plays roles in normal growth and development process of rice. The mitogen-activated protein kinase (MAPK) cascade was highly conserved among eukaryotes, which played crucial roles in plant responses to pathogen infection. Bacterial blight is the most devastating bacterial disease. Xa21 confers broad-spectrum resistance to Xanthomonas oryzae pv. Oryzae (Xoo). This study identified that the transcription level of OsMKK1 was up-regulated in resistant response against Xoo, thus overexpression (OsMKK1-OX) and RNA interference (OsMKK1-RNAi) transgenic rice lines under the background of Xa21 was constructed. Compared with recipient control plants 4021, the OsMKK1-OX lines significantly enhanced disease resistance to Xoo, on the contrary, the resistance of OsMKK1-RNAi lines was weakened, demonstrated that OsMKK1 played a positive role in Xa21-mediated disease resistance pathway. A number of pathogenesis-related proteins, including PR1A, PR2 and PR10A showed enhanced expression in OsMKK1-OX lines, supported that these PR genes may be regulated by OsMKK1 to participate in the defense responses. In addition, the agronomic traits of OsMKK1 transgenic plants were affected. Overall, these results revealed the role of OsMKK1 in Xa21-mediated resistance against Xoo and in the normal growth and development process in rice. [ABSTRACT FROM AUTHOR]

Poor osseointegration and postoperative bacterial infections are the main causes of clinical failure of titanium (Ti) based implants. In this study, calcium (Ca) and strontium (Sr), which have osteogenic activity, were simultaneously introduced into titanium dioxide nanotubes (TN) in order to balance the potential cytotoxicity of GL13K (Antibacterial peptides), and a multifunctional Sr, Ca and GL13K-doped TN (SrCaTN-GL13K) coating was successfully constructed. The results showed that the SrCaTN-GL13K coating exhibited good mechanical properties, hydrophilicity, corrosion resistance and bioactivity. Sr2+, Ca2+ and GL13K could be continuously released from the coating and was pH-responsive. In addition, SrCaTN-GL13K showed good antibacterial properties against E. coli and S. aureus with antibacterial rates of approximately 70.32% and 70.78%, respectively. Cellular assays showed that RAW264.7 (immune), human umbilical vein endothelial cell (HUVEC, angiogenic) and mouse embryo osteoblast precursor cell (MC3T3-E1, osteogenic) exhibited good adhesion, survival and proliferation activities on the SrCaTN-GL13K coated surface. At both gene level and protein level, expression of anti-inflammatory markers (Interleukin-10, IL-10; mannose receptor, CD206), angiogenic markers (vascular endothelial growth factor, VEGF; platelet endothelial cell adhesion molecule-1, CD31) and osteogenic markers (alkaline phosphatase, ALP; runt-related transcription factor 2, RUNX2; human collagen type I, COL1a1; osteocalcin, OCN) were significantly upregulated in SrCaTN-GL13K coating. At the cellular and molecular level, SrCaTN-GL13K possessed the ability to induce RAW264.7 towards M2 polarization and it possessed the ability to induce HUVEC tube-formation; meanwhile, it exhibited the ability to induce MC3T3-E1 towards osteogenic differentiation. In conclusion, Ti implants exhibited improved antibacterial, anti-inflammatory, angiogenic, and osteoinductive capabilities by loading Sr, Ca, and GL13K to alter TN. In this study, a multifunctional modification of Ti surface was achieved by an economical and efficient method, which provides a new idea for the design of antimicrobial implantable devices with immunomodulatory functions in the clinic. [ABSTRACT FROM AUTHOR]

Precisely introducing two similar functional groups into bulk chemical alkenes represents a formidable route to complex molecules. Especially, the selective activation of two electrophiles is in crucial demand, yet challenging for cross‐electrophile‐coupling. Herein, we demonstrate a redox‐mediated electrolysis, in which aryl nitriles are both aryl radical precursors and redox‐mediators, enables an intermolecular alkene 1,2‐diarylation with a remarkable regioselectivity, thereby avoiding the involvement of transition‐metal catalysts. This transformation utilizes cyanoarene radical anions for activating various aryl halides (including iodides, bromides, and even chlorides) and affords 1,2‐diarylation adducts in up to 83 % yield and >20 : 1 regioselectivity with more than 80 examples, providing a feasible approach to complex bibenzyl derivatives. [ABSTRACT FROM AUTHOR]

Precisely introducing two similar functional groups into bulk chemical alkenes represents a formidable route to complex molecules. Especially, the selective activation of two electrophiles is in crucial demand, yet challenging for cross‐electrophile‐coupling. Herein, we demonstrate a redox‐mediated electrolysis, in which aryl nitriles are both aryl radical precursors and redox‐mediators, enables an intermolecular alkene 1,2‐diarylation with a remarkable regioselectivity, thereby avoiding the involvement of transition‐metal catalysts. This transformation utilizes cyanoarene radical anions for activating various aryl halides (including iodides, bromides, and even chlorides) and affords 1,2‐diarylation adducts in up to 83 % yield and >20 : 1 regioselectivity with more than 80 examples, providing a feasible approach to complex bibenzyl derivatives. [ABSTRACT FROM AUTHOR]

Novel coronavirus disease 2019 (COVID-19) is a global pandemic caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), which can be transmitted from person to person. As of September 21, 2021, over 228 million cases were diagnosed as COVID-19 infection in more than 200 countries and regions worldwide. The death toll is more than 4.69 million and the mortality rate has reached about 2.05% as it has gradually become a global plague, and the numbers are growing. Therefore, it is important to gain a deeper understanding of the genome and protein characteristics, clinical diagnostics, pathogenic mechanisms, and the development of antiviral drugs and vaccines against the novel coronavirus to deal with the COVID-19 pandemic. The traditional biology technologies are limited for COVID-19-related studies to understand the pandemic happening. Bioinformatics is the application of computational methods and analytical tools in the field of biological research which has obvious advantages in predicting the structure, product, function, and evolution of unknown genes and proteins, and in screening drugs and vaccines from a large amount of sequence information. Here, we comprehensively summarized several of the most important methods and applications relating to COVID-19 based on currently available reports of bioinformatics technologies, focusing on future research for overcoming the virus pandemic. Based on the next-generation sequencing (NGS) and third-generation sequencing (TGS) technology, not only virus can be detected, but also high quality SARS-CoV-2 genome could be obtained quickly. The emergence of data of genome sequences, variants, haplotypes of SARS-CoV-2 help us to understand genome and protein structure, variant calling, mutation, and other biological characteristics. After sequencing alignment and phylogenetic analysis, the bat may be the natural host of the novel coronavirus. Single-cell RNA sequencing provide abundant resource for discovering the mechanism of immune response induced by COVID-19. As an entry receptor, angiotensin-converting enzyme 2 (ACE2) can be used as a potential drug target to treat COVID-19. Molecular dynamics simulation, molecular docking and artificial intelligence (AI) technology of bioinformatics methods based on drug databases for SARS-CoV-2 can accelerate the development of drugs. Meanwhile, computational approaches are helpful to identify suitable vaccines to prevent COVID-19 infection through reverse vaccinology, Immunoinformatics and structural vaccinology. Bioinformatics is the application of computational methods and analytical tools in the field of SARS-CoV-2 research which has obvious advantages in predicting the structure, product, function, and evolution of unknown genes and proteins, and in screening drugs and vaccines from a large amount of sequence information. [Display omitted] • Bioinformatics technology accelerates to revel genome and protein structure, variant calling, mutation, and other biological characteristics of SARS-CoV-2. • Bioinformatics analysis helps to find the evidence of the origin, host and evolution of the virus. • As an entry receptor, angiotensin-converting enzyme 2 (ACE2) can be used as a potential drug target to treat COVID-19. • Molecular dynamics simulation, molecular docking and artificial intelligence (AI) technology of bioinformatics methods can accelerate the development of drugs. • Bioinformatics technologies can develop the effectiveness and safety of the vaccines through reverse vaccinology, Immunoinformatics and structural vaccinology. [ABSTRACT FROM AUTHOR]

Surface modification of surgical grade titanium implants to promote bone cell integration and prevent infection is an urgent problem in orthopedic surgery. The synergistic effect of silk fibroin (SF) and strontium (Sr) has the dual functions of promoting bone formation and inhibiting osteoclasts, and silver (Ag) has excellent antibacterial activity. Therefore, this research uses technologies such as anodizing, hydrothermal synthesis, and layered self-assembly to load SF-Ag into Sr-loaded titanium dioxide nanotubes (SFAgSTN), which makes the titanium surface produce "antibacterial-bone formation" effect. The results of water contact angle and protein adsorption show that SFAgSTN has proper hydrophilicity and protein adsorption capacity, which indicates its excellent biocompatibility. The antibacterial test shows that the functional coating has excellent antibacterial activity because it can inhibit the proliferation of E. coli and S. aureus at the same time. The cross-linking effect of silk fibroin can slow down the release rate of Ag+, avoid the sudden release of ions, extend its antibacterial cycle and reduce the cytotoxicity of Ag+. In vitro, the SFAgSTN coating can promote the adhesion, proliferation and differentiation of MC3T3-E1 osteoblasts, showing good cell compatibility. In vivo, SFAgSTN promotes early osseointegration between Ti substrate and bone tissue. SFAgSTN shows excellent antibacterial, osteogenic differentiation, and new bone formation activity, and can be used as a highly potential anti-infective bone repair implant. • Silk fibroin/Ag co-functionalized strontium titanate nanotubes were prepared. • The cross-linking effect of silk fibroin can slow down the release rate of Ag+. • The coating had an exceptional antimicrobial effect for S. aureus and E. coli. • The coating showed exceptional cytocompatibility and osseointegration. [ABSTRACT FROM AUTHOR]

Effective bone repair applications of titanium-based biometals must have excellent self-antibacterial properties and osteogenesis. Due to the special nano-geometric structure of titanium dioxide nanotubes (TN), the modified TN can confer various biological functions on the surface of titanium-based biometals. In this study, we used anodization, hydrothermal synthesis, and dopamine self-assembly to develop a Sm/Sr-doped TN (SSNT) array that integrated the antibacterial properties of Sm and the bone formation properties of Sr. AFM, SEM, FTIR, EDS, and XPS methods were used to characterize the SSTN, and the antibacterial and cell compatibility of the SSTN were systematically studied. Sm ions and Sr ions were slowly and stably released from the surface of dopamine and SrTiO 3 crystals, respectively. Compared with TN, SSTN had a smaller roughness and significantly improved hydrophilicity. The colony count, inhibition zone and turbidity experiments demonstrated that the SSTN structure containing Sm had obvious antibacterial effect on E. coli and S. aureus. The nanotube structure containing strontium ions can promote the early differentiation and osteogenic gene expression of MC3T3-E1 cells adhered to the SSTN surface. Based on the above results, the dual doping of Sm and Sr, and the ideal hydrophilicity can not only improve the osteogenesis of titanium-based biometals, but also make such bone implant biometals have effective self-infection resistance. [ABSTRACT FROM AUTHOR]

Ti-based implant materials still face implant-related infections and poor osseointegration as two major clinical challenges; thus, high-quality implantation demands a strategy that can provide Ti-based implants with long-term antibacterial ability and high osteogenic activity. In this study, gallium was successfully loaded into polydopamine-functionalised SrTiO 3 nanotubes (PDA-SrTiO 3 NTs) on a titanium substrate through a facile immersion method. The release of strontium and gallium from gallium-doped SrTiO 3 NTs was controllably constant and had negligible cytotoxicity. The antibacterial efficacy of the NT coating was demonstrated by the inhibition zones of Escherichia coli and Staphylococcus aureus. The optimum contents of gallium and strontium in the coating led to enhanced cytocompatibility, osteoblast spreading and osseointegration because of the synergistic effects of strontium as a bioactive element and the porous topography of the coating surface. As observed in vivo, bone formation in rabbit-bone-defect models was improved by the proposed coating four weeks after it was implanted. According to literature, the present results show for the first time that the gallium doping of PDA-SrTiO 3 NTs can effectively stimulate osteointegration—thanks to its efficacy in enhancing implant osteoinductivity—and can prevent infections. Therefore, gallium-doped PDA-SrTiO 3 NT coatings can potentially function as promising bone implants for clinical applications. [ABSTRACT FROM AUTHOR]

Variety of ion-doped apatite coatings, especially strontium substituted hydroxyapatite (SrHA), have attracted eventful attention for medical metal surface modifications due to their excellent cytocompatibility and organizational affinity. However, they are still not commercially used in clinics because of their inappropriate biomechanical properties, and lack of osteoinductivity and antibacterial capabilities. Here, silver (Ag) doped SrHA (SrAgHA)/graphene oxide (GO) composite coatings were fabricated on titanium (Ti) substrate via electrodeposition (ED) and this combination has been reported for the first time. Morphological observations revealed that GO facilitated HA pricker-like crystals to grow in longitudinal directions, changing into a bone-like microneedles structure. SrAgHA/GO showed good mechanical properties to ensure mechanical strength required for the bone repair coating. The roughness of samples decreased from 120 ± 19 μm for the SrAgHA/GO coated Ti to 527 ± 66 μm for HA coated Ti. Although the introduction of GO makes the composite coating have a significant decreased roughness, it has no effect on the hydrophilicity of the composite coating, which is almost superpotropic. Ion release evaluation demonstrated that the presence of GO slowed the release rate of Sr and Ag, which was beneficial to reduce the cytotoxicity accompanying high concentration of Ag release. Simultaneously, GO increased the surface hydrophilicity and mechanical strength of the SrAgHA/GO. In addition, the corrosion rates of investigated coatings increased in the following order: SrAgHA/GO < SrHA/GO < SrAgHA < HA < Ti. SrAgHA/GO coatings demonstrated an effective antibacterial effect against common bacteria in clinical. The co-doping of Sr and GO in SrAgHA/GO coatings can effectively mitigate the cytotoxicity of Ag and promote the cytocompatibility of HA. The SrAgHA/GO coating did not exhibit any cytotoxicity, which can greatly promote adhesion, extension, proliferation and early differentiation of osteoblasts. Therefore, high cytocompatibility, excellent antimicrobial activity, and good mechanical properties of the SrAgHA/GO-coated Ti samples combined with its exceptional corrosion resistance performance displayed the beautiful prospect of the SrAgHA/GO-coated Ti for applications in hard tissue implant. • The SrAgHA/GO coating was fabricated by ED on titanium substrate. • The SrAgHA/GO composite coating has good mechanical properties. • The SrAgHA/GO coating has moderate roughness and hydrophilicity. • The coating had a good antimicrobial effect for E. coli and S. aureus. • The SrAgHA/GO coating exhibited excellent osteoinductivity. [ABSTRACT FROM AUTHOR]

Zinc-based biometal is expected to become a new generation of biodegradable implants. Due to its antibacterial and biocompatibility in vivo, zinc metals is recently considered to be the most promising biodegradable metal, However, cytotoxicity is the thorny problem that currently restrict its application, due to the excessive Zn ions released during degradation. In order to solve these problems, dopamine modified strontium-doped hydroxyapatite coating (SrHA/PDA) was fabricated on alkali-treated pure zinc to improve its corrosion rate and cytocompatibility by electrodeposition for the first time. The obtained coating showed a dense structure and high crystallinity, which was attributed to the attraction of Ca2+ ions by polydopamine. The results showed that the SrHA/PDA coating delayedthe degradation rate of zinc metal, which reduced the release of Zn2+, thereby reducing its cytotoxicity. Additionally, electrochemical tests showed that SrHA/PDA coating can reduce the corrosion rate of pure zinc. In vitro cell viability showed that even at high Zn2+ concentrations (3.11 mg/L), preosteoblasts (MC3T3-E1) cells proliferated at a high rate on SrHA/PDA, thus confirming that Sr2+ counteracted the cytotoxic effects of Zn2+ and promoted cell differentiation. Moreover, the SrHA/PDA coating still maintained excellent antibacterial effects against pathogenic bacterial strains (Escherichia coli and Staphylococcus aureus). Mild pH changes had no significant effect on the viability of cells and bacterias. Collectively, the present study elucidated that by coating SrHA/PDA/Zn(OH) 2 on Zn, a controllable corrosion rate, original antibacterial properties and better cell compatibility can be achieved. This provided a new strategy for the surface modification of biodegradable Zn. • SrHA/PDA was fabricated on alkali-treated pure zinc. • The SrHA/PDA coating delayed the degradation rate of zinc metal. • The SrHA/PDA coating can reduce the corrosion rate of pure zinc. • The coating had an exceptional antimicrobial effect for S. aureus and E. coli. • The coating showed exceptional cytocompatibility and osseointegration. [ABSTRACT FROM AUTHOR]

The fabrication process of the SrHA/Va/GO composite coating on Ti is shown in Graphical Abstract (for review). The following series of experiments were verified: 1) effect of GO on the mechanical properties of composite coatings; 2) the surface microstructure, phase composition, roughness, hydrophilicity of the coated implants; 3) the release behavior of Va from the SrHA/Va/GO coating; 4) the in vitro cellular responses of the composite coatings; 5) Effect of vancomycin on antibacterial properties of composite coatings. Currently, the clinical application of hydroxyapatite (HA) coatings are limited due to the lack of anti-infection, osteoinductivity and poor mechanical properties. In the present study, the strontium-containing hydroxyapatite (SrHA)/graphene oxide (GO)/vancomycin (Va) nanocomposite coating with drug delivery and antibacterial activity was fabricated by electrochemical deposition (ECD) on titanium substrate. The results showed that by inducing a large number of crystal nucleation points, the oxygen-containing groups on the two-dimensional surface of GO induced the formation of extremely fine SrHA/Va/GO composite coatings. Furthermore, the functional coating exhibited a moderately nanostructured surface with average values of roughness and contact angle of 31.9° and 126 nm, respectively, which provided a suitable contact surface for osteoblast proliferation and differentiation. Moreover, compared with HA coatings without GO, the hardness and elastic modulus of SrHA/Va/GO composite coatings were enhanced by 67.6 % and 121 %, respectively. The release process of Va from the SrHA/Va/GO coating showed a phased release law, which broke out within the first 5 h and then slowly and controlledly released within 14 h, which is due to the physical and chemical adsorption of Va. The inhibition zone and colony count experiments showed that the SrHA/Va/GO coating revealed satisfactory inhibitory effects on S. aureus and S. epidermidis, and the inhibition could last for 3 days. Compared with pure titanium, SrHA/Va/GO composite coating can significantly promote the adhesion, proliferation and differentiation of MC3T3-E1 cells. In conclusion, SrHA/Va/GO exhibited good mechanical properties, excellent osteoinductivity and antibacterial properties, confirming its potential as a new surface modification material for the prevention and treatment of infectious bone defects. [ABSTRACT FROM AUTHOR]