Spotlights pubs.acs.org/JPCL
Spotlights: Volume 8, Issue 1
■
COLOR RICHNESS IN CEPHALOPOD CHROMATOPHORES ORIGINATING FROM HIGH REFRACTIVE INDEX BIOMOLECULES The longfin inshore squid may be an appetizing snack for some dolphins, whales, and fish, but this cephalopod has a trick up its proverbial sleeve: camouflage! Doryteuthis pealeii, like many cephalopods, can change color in response to stimuli such as predators. But how does the process work, and how can we mimic it? Scientists have long studied the chemical, nanoarchitectural, and optical properties of the rapidly actuating component of coloration in cephalopodsthe chromatophorebut these properties have yet to be fully detailed. As a result, many of the bioinspired conformal displays that have drawn from nature’s design of hierarchical nanophotonic systems fail to achieve comparable rapid and versatile optical functions across the visible spectrum. In their Letter, Dinneen et al. (DOI: 10.1021/acs.jpclett.6b02398) studied the structure−function relationships of the chromatophore of D. pealeii. The authors describe a biophysical mechanism potentiating the dynamic coloration in cephalopods originating from pigments localized within chromatophores. Through theoretical and experimental means, they calculated the pigment’s complex refractive index as 1.92 + 0.014i. They used Mie theory to infer a mechanism describing color richness in cephalopods that is due to the native geometry of the pigments. In the cephalopod chromatophore, the pigments are localized within nanostructured granules, and the authors show how these granules enhance the scattering of light in a process that may enrich the broad range of visible colors observed during camouflage. These findings enhance our understanding of the fast response time of chromatophores during actuation in cephalopods and may inform future engineering of biophotonic systems.
from the hydrocarbon region to the aqueous environment. The findings reaffirm that neutron reflectometry is well suited for structural studies of membrane-associating proteins at the lipid/ water interface. Furthermore, the authors’ detailed method to produce proteins by native chemical ligation with milligram yields could be extended to other intrinsically disordered proteins and techniques such as Raman, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy.
■
HIGHLY EFFICIENT ALL-INORGANIC PLANAR HETEROJUNCTION PEROVSKITE SOLAR CELLS PRODUCED BY THERMAL COEVAPORATION OF CsI AND PbI2 Exceeding 10% power conversion efficiency is broadly accepted as a major step toward the maturity of a photovoltaic technology. Hybrid organic−inorganic perovskite solar cells have demonstrated impressive power conversion efficiencies of >22% on the best laboratory samples, thus coming very close to the advanced silicon-based technologies. However, commercialization of these hybrid perovskite photovoltaics is hampered severely by very poor stability of these devices under realistic solar cell operational conditions. Hybrid perovskites incorporating organic cations undergo facile and rapid thermal and photochemical decomposition, which challenges their practical implementation in solar modules. All-inorganic perovskites (e.g., CsPbBr3 and CsPbI3) show outstanding robustness and stability to thermal-induced chemical degradation mechanisms and photochemical-induced bleaching processes, while their solar cell performances generally remain diminished compared with the conventional hybrid perovskite materials such as CH3NH3PbI3. In their Letter, Frolova et al. (DOI: 10.1021/ acs.jpclett.6b02594) demonstrate efficient planar heterojunction solar cells based on all-inorganic CsPbI3 perovskite films produced by thermal coevaporation of CsI and PbI2. These devices showed maximal power conversion efficiencies exceeding 10%, good reproducibility, and reasonably low hysteresis in current−voltage characteristics. Reference samples based on CH3NH3PbI3 films delivered just slightly higher performances of 10−12% in the same device configuration. These results demonstrate that all-inorganic perovskites can deliver competitive photovoltaic performances, thus paving improved routes to design of novel materials for efficient and stable perovskite-based photovoltaics.
■
SEGMENTAL DEUTERATION OF α-SYNUCLEIN FOR NEUTRON REFLECTOMETRY ON TETHERED BILAYERS The symptoms of Parkinson’s disease are well known, but its causes remain unclear. Scientists have found that α-synuclein, a membrane-binding neuronal protein present in Lewy bodies, may hold the answer, and much work is being done in this area. In their Letter, Jiang et al. (DOI: 10.1021/acs.jpclett.6b02304) describe the successful coupling of native chemical ligation with neutron reflectometry, an emerging scattering technique in studying protein interaction with phospholipid bilayers. Employing native chemical ligation, the authors generated segmentally deuterated α-synuclein where either the first 86 or last 54 residues were deuterated. Contrast between the two segments was achieved from the neutron scattering length density difference between protium and deuterium atoms. The authors successfully applied these segmentally deuterated αsynuclein variants in neutron reflectometry measurements to detect region-specific membrane interaction. They found that residues 1−86 were positioned around the hydrocarbon/ headgroup interface of the outer leaflet, whereas the density distribution of the C-terminal 54 residues was diffuse, ranging © 2017 American Chemical Society
Published: January 5, 2017 318
DOI: 10.1021/acs.jpclett.6b03013 J. Phys. Chem. Lett. 2017, 8, 318−318
