Spotlights pubs.acs.org/JACS
Spotlights on Recent JACS Publications
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NUCLEIC ACID AMPLIFICATION GETS THE GOLDEN TOUCH Nucleic acid amplification (NAA) methods, which create many copies of a small sample of DNA for biological and biomedical research and applications, rely on heating the sample or alternating cycles of heating and cooling. However, the instrumentation used to meet these temperature requirements is typically expensive, time-consuming, heavy, and energetically draining. Yossi Weizmann and colleagues report a novel nanoparticle-based technique that achieves rapid and low-energy thermocycling for uniform and steady heating for various NAA strategies (DOI: 10.1021/jacs.7b01779). The researchers accomplish this goal using gold bipyramidal nanoparticles (AuBPs), which are able to convert light to heat through plasmonic photothermal (PPT) effects. The team adds AuBPs to a typical reaction solution in a standard tube for quantitative polymerase chain reaction (qPCR), a NAA technique that depends on thermocycling. Using a LED as a light source, they produce reliable and reproducible amplification in real time. Additional experiments show that this PPT technique could also be used for other widely used biological assays, including restriction digestion of a DNA plasmid. PPT-based NAA could thus have applications in many biological fields. Christen Brownlee
CLEARING UP CONTAMINATION WITH CYCLODEXTRIN POLYMERS Thermodynamic stability of chemical bonds is an asset in many contexts. But when it comes to environmental contamination, it is highly problematic. This is the case with per- and poly-fluorinated alkyl substances, such as perfluorooctanoic acid (PFOA), which is used in industrial processes, consumer products, and fire suppression. Given the stability of C−F bonds, PFOA is environmentally persistent and difficult to degrade. It has been found in ground and surface waters, where it poses risks to human health and the environment. Due to the performance limitations of existing methods for clearing up PFOA contamination, researchers have been working on developing more effective adsorbents. William Dichtel, Damian E. Helbling, and co-workers describe a new βcyclodextrin polymer network that sequesters PFOA in water at environmentally relevant levels to well below EPA health advisory limits (DOI: 10.1021/jacs.7b02381). The team shows the polymer outperforms activated carbons and can be regenerated and reused multiple times. The researchers also demonstrate that performance is unaffected by the presence of humic acid, a component of natural organic matter known for fouling activated carbon, making the material a promising candidate for PFOA remediation. Christine Herman, Ph.D.
SMALL-MOLECULE SYSTEM ADDRESSES LIMITATION OF PHOTODYNAMIC CANCER THERAPY During photodynamic cancer therapy (PDT), a small molecule photosensitizer is injected into the bloodstream of a patient. Although the molecule is absorbed by tissues throughout the body, it typically persists longer in cancer cells. When the tumor is exposed to light, the photosensitizer absorbs the light and produces singlet oxygen, which kills cancer cells. One of the primary limitations of the treatment is the occurrence of PDTinduced hypoxia, which can lead to cancer recurrence and progression through the formation of new blood vessels to the tumor, known as angiogenesis. Now, Jonathan L. Sessler, Jin Yong Lee, Jong-Hoon Kim, and Jong Seung Kim and colleagues report a new small-molecule system that may be able to address this limitation of PDT (DOI: 10.1021/jacs.7b02396). The photosensitizer they use, AZ-BPS, is composed of acetazolamide (AZ)-conjugated to a BODIPY photosensitizer (BPS). The AZ moiety helps both target the ligand to cancer cells and inhibit carbonic anhydrase IX (CAIX), which is involved in angiogenesis. Meanwhile, the BPS serves as a singlet-oxygen-producing photosensitizer that also enables fluorescence-based tracking of cellular uptake and distribution. The team has observed enhanced photo-cytotoxicity of AZ-BPS compared to BPS alone in cancer cells both in vitro and in vivo. The work suggests AZ-BPS holds promise as a therapeutic method for targeting CAIX-overexpressing tumors. Christine Herman, Ph.D. © 2017 American Chemical Society
ORDER UP! REDUCING CO2 WITH ORDERED NANOPARTICLE GOLD−COPPER ALLOYS Multimetallic nanoparticles (NPs) have been extensively studied for applications such as catalysis, where having multiple components can overcome drawbacks inherent in singlecomponent systems. Besides simply controlling which elements are included and at what ratios, it is also possible in some systems to control the precise placement of atoms, distinguishing disordered systems from ordered ones. Peidong Yang and coworkers show that this order−disorder dichotomy in AuCu NPs can make the difference in effectively reducing CO2, an important problem in storing renewable energy as fuel (DOI: 10.1021/ jacs.7b03516). The researchers create a range of AuCu NPs with a 1:1 ratio of each component but different levels of ordering; incorporation of Cu into Au NP seeds at longer times and higher temperatures leads to greater ordering. The team shows that higher ordering leads to greater electrochemical reduction of CO2 to CO. The most highly ordered NPs have a thin gold shell that is likely responsible for catalytic activity. With the wealth of multimetallic NPs available, ordering could hold promise for applications in other systems. Christen Brownlee
Published: June 21, 2017 8053
DOI: 10.1021/jacs.7b05996 J. Am. Chem. Soc. 2017, 139, 8053−8053
