Bioengineered materials with selective antimicrobial toxicity in biomedicine

Fungi and bacteria afflict humans with innumerous pathogen-related infections and ailments.Most of the commonly employed microbicidal agents target commensal and pathogenic microorganisms without discrimination.To distinguish and fight the pathogenic species out of the microflora,novel antimicrobials have been developed that selectively target specific bacteria and fungi.The cell wall features and antimicrobial mechanisms that these microorganisms involved in are highlighted in the present review.This is followed by reviewing the design of antimicrobials that selectively combat a specific community of microbes including Gram-positive and Gram-negative bacterial strains as well as fungi.Finally,recent advances in the antimicrobial immunomodulation strategy that enables treating microorganism infections with high specificity are reviewed.These basic tenets will enable the avid reader to design novel approaches and compounds for antibacterial and antifungal applications.

Engineered high-strength biohydrogel as a multifunctional platform to deliver nucleic acid for ameliorating intervertebral disc degeneration

Intervertebral disc degeneration(IVDD)is a leading cause of low back pain.The strategy of using functional materials to deliver nucleic acids provides a powerful tool for ameliorating IVDD.However,the immunogenicity of nucleic acid vectors and the poor mechanical properties of functional materials greatly limit their effects.Herein,antagomir-204-3p(AM)shows low immunogenicity and effectively inhibits the apoptosis of nucleus pulposus cells.Moreover,a high-strength biohydrogel based on zinc-oxidized sodium alginate-gelatin(ZOG)is designed as a multifunctional nucleic acid delivery platform.ZOG loaded with AM(ZOGA)exhibits great hygroscopicity,antibacterial activity,biocompatibility,and biodegradability.Moreover,ZOGA can be cross-linked with nucleus pulposus tissue to form a high-strength collagen network that improves the mechanical properties of the intervertebral disc(IVD).In addition,ZOGA provides an advantageous microenvironment for genetic expression in which AM can play an efficient role in maintaining the metabolic balance of the extracellular matrix.The results of the radiological and histological analyses demonstrate that ZOGA restores the height of the IVD,retains moisture in the IVD,and maintains the tissue structure.The ZOGA platform shows the sustained release of nucleic acids and has the potential for application to ameliorate IVDD,opening a path for future studies related to IVD.

Effect of Functionalized Magnetite Nanoparticles and Diaminoxanthone on the Curing, Thermal Degradation Kinetic and Corrosion Property of Diglycidyl Ether of Bisphenol A-Based Epoxy Resin

To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone（DAX） was used to cure diglycidylether of bisphenol-A（DGEBA）-based epoxy resin and blend of DGEBA with functionalized Fe3O4 nanoparticles. Kinetic parameters of curing and thermal degradation of epoxy resin systems were estimated by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）, respectively. The 10% weight loss temperature has been increased from 340 °C to 366 °C and there was an increase in the char yield from 32.6% to 45.3% for the above systems. The corrosion performance of epoxy coated carbon steel was examined by potentiodynamic polarization, along with immersion test in 1.0 mol/L HCl solution. The results showed that epoxy resins cured with DAX had low tendency to corrosion. In addition, the cured epoxy resin containing 10% Fe3O4 had higher anticorrosion activity than bare DGEBA system. The results showed that functionalized Fe3O4 nanoparticles enhanced char formation and improved the thermal stability as well as anticorrosion activity of the resin.

Lawsone-encapsulated chitosan/polyethylene oxide nanofibrous mat as a potential antibacterial biobased wound dressing

Biodegradable and absorptive wound dresses with antibacterial activity are in demand to accelerate wound heal-ing along with eliminating bacterial infection.Plant-derived naphthoquinones compounds such as lawsone have shown sustained antibacterial functions to avoid development of bacterial resistance by reducing pH or attaching to bacterial proteins.Here the nanofibrous mats based on chitosan/polyethylene oxide(PEO)fibers containing various concentrations of lawsone(0,1,3,7,10%wt.)were fabricated by electrospinning for potential applications as wound dressing materials.The results exhibited that the chitosan/PEO/Lawsone nanofibers possess antibacterial activity toward Gram-negative and-positive bacteria.Surprisingly,the addition of lawsone in the proper amount into chitosan/PEO nanofibers not only introduced an antithetical property but also reduced the platform’s cytotoxicity,promoting cell viability of normal human fibroblast cells.Accordingly,the achieved data suggest the potential application of biocompatible nanofibrous mats as an antibacterial wound dressing material.