SCIENCE & TECHNOLOGY CONCENTRATES
a tandem cell with a conversion efficiency of more than 25%.—MJ
NEWLY ENGINEERED TISSUE SHEDS LIGHT ON FIBROCARTILAGE Fibrocartilage is a type of tissue, such as that in the knee meniscus, that consists of aligned fibrous microdomains with nonfibrous proteoglycan-rich microdomain inclusions. The role of these different domains in growth and development, aging, and disease is not well understood. Dawn M. Elliott of the University of Delaware, Robert L. Mauck of the University of Pennsylvania, and coworkers have now quantified the proteoglycan microdomains in knee fibrocartilage from fetal, juvenile, and adult cows and from adult humans and assessed the tissue’s response to strain (Nat. Mater. 2016, DOI: 10.1038/nmat4520). The number of proteoglycan microdomains reached a steady state
WOOJIN HAN AND SU CHIN HEO
Heterogeneous tissue-engineered constructs reproduce the microstructural, micromechanical, and mechanobiological features of natural fibrocartilage. This image shows interactions between fibrous (red) and proteoglycan-rich (blue) microdomains.
at the juvenile stage, they found, but the size of the proteoglycan domains continued to increase throughout aging. In humans, the size, but not the number, of inclusions correlated with age, body mass index, and diagnosis of osteoarthritis. The researchers separately engineered fibrocartilage by seeding cells on a polymer scaffold. One type of cell deposits the collagen matrix, and another type of cell deposits proteoglycans. The mechanical and signaling response of the engineered tissue to tensile strain matched that of the natural tissue. The engineered tissue thus provides a new tool for scientists to develop treatments for disease or injury, the researchers conclude.—CHA
INSOLUBLE CATALYST WORKS WONDERS A growing number of chemists are turning to water as an environmentally friendly
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by-product of this degradation, magnesium hydroxide, spurs calcium phosphate formation near + the screw. This (pinacol)B–Si(CH3)2Ph Si(CH3)2Ph activity, in turn, O O helps induce R´ R R´ R bone growth, says R,R´= various groups, team member HyungPh = phenyl Seop Han of the Korea Institute of alternative to standard organic solvents— Science & Technology. The screws, which water is abundant, inexpensive, nonflamwere approved by the Korea Food & Drug mable, and nontoxic. In one example, Shū Administration in April, help fractures heal Kobayashi and coworkers at the University completely in about a year, he adds.—MD of Tokyo have been exploring the use of nonimmobilized chiral heterogeneous PLANT COMPOUND catalysts in water. Although the catalysts are insoluble in water, they nevertheless MIMICS BACTERIAL can mediate reactions between lipophilic COMMUNICATIONS reagents. The Tokyo researchers have now paired copper acetylacetonate with a chiral Bacteria often coordinate efforts chemibipyridine ligand for the enantioselective cally with their neighbors using a process addition of silylboronates to a range of α,βcalled quorum sensing. The microbes reunsaturated acceptor molecules (J. Am. lease molecules that they all recognize as Chem. Soc. 2015, DOI: 10.1021/jacs.5b11418). signals for common activities such as formThe products feature a chiral silyl group, ing a biofilm or releasing toxic virulence which is a convenient placeholder for a C–C factors to attack a host. A study has now or C–O bond that can be formed in later found that a compound made by plants, steps. The new reactions only proceed in rosmarinic acid, can mimic the actions of water and don’t work in organic solvents a common class of quorum-sensing molwhen the catalyst or reactants are soluble. ecules (Sci. Signaling 2016, DOI: 10.1126/ The team believes water plays a prominent scisignal.aaa8271). Plants may use rosmarole in constructing and stabilizing sterically rinic acid to protect themselves against confined, rigid transition states and accelerinfections by butting into bacterial converating subsequent protonation leading to the sations, a strategy scientists could adopt high yields and enantioselectivities.—SR in the design of new antimicrobial drugs. Through computational modeling and microcalorimetry experiments, Tino Krell of MAGNESIUM’S the Spanish National Research Council and colleagues found that rosmarinic acid can MEDICAL METTLE bind to a known quorum-sensing regulator Metal corrosion is usually a bad thing, protein used by the pathogenic bacteria but in some instances it can be beneficial, Pseudomonas aeruginosa. The compound is even therapeutic. For example, scientists more potent than the bacteria’s own quohave been developing biodegradable rum-sensing molecule, a homoserine lacmetal alloys that appear to promote healOH ing when used as replacements for conO OH OH ventional noncorrosive metal pins and O screws used to fix broken bones. A team of O South Korean and Canadian researchers has now shown how magnesium screws HO laced with calcium and zinc—elements OH known to promote bone health—help heal Rosmarinic acid small fractures in hands and wrists (Proc. Natl. Acad. Sci. USA 2016, DOI: 10.1073/ tone, binding tighter to the regulator and pnas.1518238113). Using a variety of techstimulating greater levels of gene expresniques, including fluorescence microscopy sion. The researchers think rosmarinic acid and energy-dispersive X-ray spectroscopy, makes bacteria vulnerable by forcing them the team tracked the water-driven degrato jump the gun on a sensing response bedation of screws inside patients at Ajou fore they have sufficient numbers to reach University Hospital for several months. A a quorum.—MT A water-insoluble chiral copper catalyst manages to orchestrate asymmetric silyl additions in water.
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