Pub Date : 2024-06-17DOI: 10.1021/acs.nanolett.3c04180
Abhishek Kumar, Jonas Müller, Sylvain Pelloquin, Aurélie Lecestre and Guilhem Larrieu*,
Vertical gate-all-around (V-GAA) represents the ultimate configuration in the forthcoming transistor industry, but it still encounters challenges in the semiconductor community. This paper introduces, for the first time, a dual-input logic gate circuit achieved using 3D vertical transistors with nanoscale sub-20-nm GAA, employing a novel technique for creating contacts and patterning metallic lines at the bottom level without the conventional lift-off process. This involves a two-step oxidation process: patterning the first field oxide to form bottom metal lines and then creating the gate oxide layer on nanowires (NWs), followed by selective removal from the top and bottom of the nanostructures. VGAA-NW transistors, fabricated using the lift-off-free approach, exhibit improved yield and reduced access resistance, leading to an enhanced drive current while maintaining good immunity against short-channel effects. Finally, elementary two-input logic gates within a single cell, using VNW transistors, demonstrate novel possibilities in advanced logic circuitry design and routing options in 3D.
{"title":"Logic Gates Based on 3D Vertical Junctionless Gate-All-Around Transistors with Reliable Multilevel Contact Engineering","authors":"Abhishek Kumar, Jonas Müller, Sylvain Pelloquin, Aurélie Lecestre and Guilhem Larrieu*, ","doi":"10.1021/acs.nanolett.3c04180","DOIUrl":"10.1021/acs.nanolett.3c04180","url":null,"abstract":"<p >Vertical gate-all-around (V-GAA) represents the ultimate configuration in the forthcoming transistor industry, but it still encounters challenges in the semiconductor community. This paper introduces, for the first time, a dual-input logic gate circuit achieved using 3D vertical transistors with nanoscale sub-20-nm GAA, employing a novel technique for creating contacts and patterning metallic lines at the bottom level without the conventional lift-off process. This involves a two-step oxidation process: patterning the first field oxide to form bottom metal lines and then creating the gate oxide layer on nanowires (NWs), followed by selective removal from the top and bottom of the nanostructures. VGAA-NW transistors, fabricated using the lift-off-free approach, exhibit improved yield and reduced access resistance, leading to an enhanced drive current while maintaining good immunity against short-channel effects. Finally, elementary two-input logic gates within a single cell, using VNW transistors, demonstrate novel possibilities in advanced logic circuitry design and routing options in 3D.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acs.nanolett.3c04180","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-17DOI: 10.1021/acs.nanolett.4c02192
Yutong Zhu, Xi Deng, Zideng Dai, Qing Liu, Yichen Kuang, Tianzhi Liu* and Hangrong Chen*,
The unique “Iron Addiction” feature of cancer stem cells (CSCs) with tumorigenicity and plasticity generally contributes to the tumor recurrence and metastasis after a lumpectomy. Herein, a novel “Ferroptosis Amplification” strategy is developed based on integrating gallic acid-modified FeOOH (GFP) and gallocyanine into Pluronic F-127 (F127) and carboxylated chitosan (CC)-based hydrogel for CSCs eradication. This “Ferroptosis Amplifier” hydrogel is thermally sensitive and achieves rapid gelation at the postsurgical wound in a breast tumor model. Specifically, gallocyanine, as the Dickkopf-1 (DKK1) inhibitor, can decrease the expression of SLC7A11 and GPX4 and synergistically induce ferroptosis of CSCs with GFP. Encouragingly, it is found that this combination suppresses the migratory and invasive capability of cancer cells via the downregulation of matrix metalloproteinase 7 (MMP7). The in vivo results further confirm that this “Ferroptosis Amplification” strategy is efficient in preventing tumor relapse and lung metastasis, manifesting an effective and promising postsurgical treatment for breast cancer.
{"title":"A “Ferroptosis-Amplifier” Hydrogel for Eliminating Refractory Cancer Stem Cells Post-lumpectomy","authors":"Yutong Zhu, Xi Deng, Zideng Dai, Qing Liu, Yichen Kuang, Tianzhi Liu* and Hangrong Chen*, ","doi":"10.1021/acs.nanolett.4c02192","DOIUrl":"10.1021/acs.nanolett.4c02192","url":null,"abstract":"<p >The unique “Iron Addiction” feature of cancer stem cells (CSCs) with tumorigenicity and plasticity generally contributes to the tumor recurrence and metastasis after a lumpectomy. Herein, a novel “Ferroptosis Amplification” strategy is developed based on integrating gallic acid-modified FeOOH (GFP) and gallocyanine into Pluronic F-127 (F127) and carboxylated chitosan (CC)-based hydrogel for CSCs eradication. This “Ferroptosis Amplifier” hydrogel is thermally sensitive and achieves rapid gelation at the postsurgical wound in a breast tumor model. Specifically, gallocyanine, as the Dickkopf-1 (DKK1) inhibitor, can decrease the expression of SLC7A11 and GPX4 and synergistically induce ferroptosis of CSCs with GFP. Encouragingly, it is found that this combination suppresses the migratory and invasive capability of cancer cells <i>via</i> the downregulation of matrix metalloproteinase 7 (MMP7). The <i>in vivo</i> results further confirm that this “Ferroptosis Amplification” strategy is efficient in preventing tumor relapse and lung metastasis, manifesting an effective and promising postsurgical treatment for breast cancer.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The metal-semiconductor interface fabricated by conventional methods often suffers from contamination, degrading transport performance. Herein, we propose a one-pot chemical vapor deposition (CVD) process to create a two-dimensional (2D) MoO2-MoSe2 heterostructure by growing MoO2 seeds under a hydrogen environment, followed by depositing MoSe2 on the surface and periphery. The ultraclean interface is verified by cross-sectional scanning transmission electron microscopy and photoluminescence. Along with the high work function of semimetallic MoO2 (Ef = -5.6 eV), a high-rectification Schottky diode is fabricated based on this heterostructure. Furthermore, the Schottky diode exhibits an excellent photovoltaic effect with a high open-circuit voltage of 0.26 eV and ultrafast photoresponse, owing to the naturally formed metal-semiconductor contact with suppressed pinning effect. Our method paves the way for the fabrication of an ultraclean 2D metal-semiconductor interface, without defects or contamination, offering promising prospects for future nanoelectronics.
{"title":"Epitaxial Growth of Two-Dimensional MoO<sub>2</sub>-MoSe<sub>2</sub> Metal-Semiconductor Heterostructures for Schottky Diodes.","authors":"Ting Kang, Jiawen You, Jun Wang, Yuyin Li, Yunxia Hu, Tsz Wing Tang, Xiaohui Lin, Yunxin Li, Liting Liu, Zhaoli Gao, Yuan Liu, Zhengtang Luo","doi":"10.1021/acs.nanolett.4c01865","DOIUrl":"10.1021/acs.nanolett.4c01865","url":null,"abstract":"<p><p>The metal-semiconductor interface fabricated by conventional methods often suffers from contamination, degrading transport performance. Herein, we propose a one-pot chemical vapor deposition (CVD) process to create a two-dimensional (2D) MoO<sub>2</sub>-MoSe<sub>2</sub> heterostructure by growing MoO<sub>2</sub> seeds under a hydrogen environment, followed by depositing MoSe<sub>2</sub> on the surface and periphery. The ultraclean interface is verified by cross-sectional scanning transmission electron microscopy and photoluminescence. Along with the high work function of semimetallic MoO<sub>2</sub> (<i>E</i><sub>f</sub> = -5.6 eV), a high-rectification Schottky diode is fabricated based on this heterostructure. Furthermore, the Schottky diode exhibits an excellent photovoltaic effect with a high open-circuit voltage of 0.26 eV and ultrafast photoresponse, owing to the naturally formed metal-semiconductor contact with suppressed pinning effect. Our method paves the way for the fabrication of an ultraclean 2D metal-semiconductor interface, without defects or contamination, offering promising prospects for future nanoelectronics.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":10.8,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-17DOI: 10.1021/acs.nanolett.4c01697
Yi Wang, Haiyan Peng, Meiyang Song, Henghui Song, Yuhui Liu, Peng Chen* and Shuang-Feng Yin*,
Direct nitrogen oxidation into nitrate under ambient conditions presents a promising strategy for harsh and multistep industrial processes. However, the dynamic structural evolution of active sites in surface reactions constitutes a highly intricate endeavor and remains in its nascent stage. Here, we constructed a Bi24O31Cl10 material with moiré superlattice structure (BCMS) for direct piezo-photocatalytic oxidation of nitrogen into nitrate. Excitingly, BCMS achieved excellent nitric acid production (15.44 mg g–1 h–1) under light and pressure conditions. Detailed experimental results show that the unique structure extracts the local strain tensor from the constricting Bi–Bi bond and Bi–O bond for internal structural reconstruction, which promotes the formation of electron and reactive molecule vortexes to facilitate charge transfer as well as N2 and O2 adsorption. Ultimately, these initiatives strengthen electron exchange between the superoxide radical and nitrogen as well as the binding strength of multiple intermediates, which swayingly adjusts the reaction path and energy barriers.
{"title":"Tuning Dynamic Structural Evolution of Bi24O31Cl10 for Enhancing Piezo-Photocatalytic Nitrogen Oxidation to Nitrate","authors":"Yi Wang, Haiyan Peng, Meiyang Song, Henghui Song, Yuhui Liu, Peng Chen* and Shuang-Feng Yin*, ","doi":"10.1021/acs.nanolett.4c01697","DOIUrl":"10.1021/acs.nanolett.4c01697","url":null,"abstract":"<p >Direct nitrogen oxidation into nitrate under ambient conditions presents a promising strategy for harsh and multistep industrial processes. However, the dynamic structural evolution of active sites in surface reactions constitutes a highly intricate endeavor and remains in its nascent stage. Here, we constructed a Bi<sub>24</sub>O<sub>31</sub>Cl<sub>10</sub> material with moiré superlattice structure (BCMS) for direct piezo-photocatalytic oxidation of nitrogen into nitrate. Excitingly, BCMS achieved excellent nitric acid production (15.44 mg g<sup>–1</sup> h<sup>–1</sup>) under light and pressure conditions. Detailed experimental results show that the unique structure extracts the local strain tensor from the constricting Bi–Bi bond and Bi–O bond for internal structural reconstruction, which promotes the formation of electron and reactive molecule vortexes to facilitate charge transfer as well as N<sub>2</sub> and O<sub>2</sub> adsorption. Ultimately, these initiatives strengthen electron exchange between the superoxide radical and nitrogen as well as the binding strength of multiple intermediates, which swayingly adjusts the reaction path and energy barriers.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-17DOI: 10.1021/acs.nanolett.4c01618
Jie Zhang, Dawei Yang*, Canhuang Li, Qianhong Gong, Wei Bi, Xuejiao Zheng, Jordi Arbiol, Shengjun Li and Andreu Cabot*,
The development of advanced cathode materials able to promote the sluggish redox kinetics of polysulfides is crucial to bringing lithium–sulfur batteries to the market. Herein, two electrode materials: namely, Zr2PS2 and Zr2PTe2, are identified through screening several hundred thousand compositions in the Inorganic Crystal Structure Database. First-principles calculations are performed on these two materials. These structures are similar to that of the classical MXenes. Concurrently, calculations show that Zr2PS2 and Zr2PTe2 possess high electrical conductivity, promote Li ion diffusion, and have excellent electrocatalytic activity for the Li–S reaction and particularly for the Li2S decomposition. Besides, the mechanisms behind the excellent predicted performance of Zr2PS2 and Zr2PTe2 are elucidated through electron localization function, charge density difference, and localized orbital locator. This work not only identifies two candidate sulfur cathode additives but may also serve as a reference for the identification of additional electrode materials in new generations of batteries, particularly in sulfur cathodes.
{"title":"Two-Dimensional Transition Metal Phosphides As Cathode Additive in Robust Lithium–Sulfur Batteries","authors":"Jie Zhang, Dawei Yang*, Canhuang Li, Qianhong Gong, Wei Bi, Xuejiao Zheng, Jordi Arbiol, Shengjun Li and Andreu Cabot*, ","doi":"10.1021/acs.nanolett.4c01618","DOIUrl":"10.1021/acs.nanolett.4c01618","url":null,"abstract":"<p >The development of advanced cathode materials able to promote the sluggish redox kinetics of polysulfides is crucial to bringing lithium–sulfur batteries to the market. Herein, two electrode materials: namely, Zr<sub>2</sub>PS<sub>2</sub> and Zr<sub>2</sub>PTe<sub>2</sub>, are identified through screening several hundred thousand compositions in the Inorganic Crystal Structure Database. First-principles calculations are performed on these two materials. These structures are similar to that of the classical MXenes. Concurrently, calculations show that Zr<sub>2</sub>PS<sub>2</sub> and Zr<sub>2</sub>PTe<sub>2</sub> possess high electrical conductivity, promote Li ion diffusion, and have excellent electrocatalytic activity for the Li–S reaction and particularly for the Li<sub>2</sub>S decomposition. Besides, the mechanisms behind the excellent predicted performance of Zr<sub>2</sub>PS<sub>2</sub> and Zr<sub>2</sub>PTe<sub>2</sub> are elucidated through electron localization function, charge density difference, and localized orbital locator. This work not only identifies two candidate sulfur cathode additives but may also serve as a reference for the identification of additional electrode materials in new generations of batteries, particularly in sulfur cathodes.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-17DOI: 10.1021/acs.nanolett.4c01247
Markus Aspegren, Lila Chergui, Mikelis Marnauza, Rousan Debbarma, Jakob Bengtsson, Sebastian Lehmann, Kimberly A. Dick, Stephanie M. Reimann and Claes Thelander*,
In nanoscale structures with rotational symmetry, such as quantum rings, the orbital motion of electrons combined with a spin–orbit interaction can produce a very strong and anisotropic Zeeman effect. Since symmetry is sensitive to electric fields, ring-like geometries provide an opportunity to manipulate magnetic properties over an exceptionally wide range. In this work, we show that it is possible to form rotationally symmetric confinement potentials inside a semiconductor quantum dot, resulting in electron orbitals with large orbital angular momentum and strong spin−orbit interactions. We find complete suppression of Zeeman spin splitting for magnetic fields applied in the quantum dot plane, similar to the expected behavior of an ideal quantum ring. Spin splitting reappears as orbital interactions are activated with symmetry-breaking electric fields. For two valence electrons, representing a common basis for spin-qubits, we find that modulating the rotational symmetry may offer new prospects for realizing tunable protection and interaction of spin–orbital states.
{"title":"Perfect Zeeman Anisotropy in Rotationally Symmetric Quantum Dots with Strong Spin–Orbit Interaction","authors":"Markus Aspegren, Lila Chergui, Mikelis Marnauza, Rousan Debbarma, Jakob Bengtsson, Sebastian Lehmann, Kimberly A. Dick, Stephanie M. Reimann and Claes Thelander*, ","doi":"10.1021/acs.nanolett.4c01247","DOIUrl":"10.1021/acs.nanolett.4c01247","url":null,"abstract":"<p >In nanoscale structures with rotational symmetry, such as quantum rings, the orbital motion of electrons combined with a spin–orbit interaction can produce a very strong and anisotropic Zeeman effect. Since symmetry is sensitive to electric fields, ring-like geometries provide an opportunity to manipulate magnetic properties over an exceptionally wide range. In this work, we show that it is possible to form rotationally symmetric confinement potentials inside a semiconductor quantum dot, resulting in electron orbitals with large orbital angular momentum and strong spin−orbit interactions. We find complete suppression of Zeeman spin splitting for magnetic fields applied in the quantum dot plane, similar to the expected behavior of an ideal quantum ring. Spin splitting reappears as orbital interactions are activated with symmetry-breaking electric fields. For two valence electrons, representing a common basis for spin-qubits, we find that modulating the rotational symmetry may offer new prospects for realizing tunable protection and interaction of spin–orbital states.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acs.nanolett.4c01247","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-17DOI: 10.1021/acs.nanolett.4c01407
Wei Yuan, Zi-Jie Yan, Hemian Yi, Zihao Wang, Stephen Paolini, Yi-Fan Zhao, Lingjie Zhou, Annie G. Wang, Ke Wang, Thomas Prokscha, Zaher Salman, Andreas Suter, Purnima P. Balakrishnan, Alexander J. Grutter, Laurel E. Winter, John Singleton, Moses H. W. Chan and Cui-Zu Chang*,
The interface of two materials can harbor unexpected emergent phenomena. One example is interface-induced superconductivity. In this work, we employ molecular beam epitaxy to grow a series of heterostructures formed by stacking together two nonsuperconducting antiferromagnetic materials, an intrinsic antiferromagnetic topological insulator MnBi2Te4 and an antiferromagnetic iron chalcogenide FeTe. Our electrical transport measurements reveal interface-induced superconductivity in these heterostructures. By performing scanning tunneling microscopy and spectroscopy measurements, we observe a proximity-induced superconducting gap on the top surface of the MnBi2Te4 layer, confirming the coexistence of superconductivity and antiferromagnetism in the MnBi2Te4 layer. Our findings will advance the fundamental inquiries into the topological superconducting phase in hybrid devices and provide a promising platform for the exploration of chiral Majorana physics in MnBi2Te4-based heterostructures.
{"title":"Coexistence of Superconductivity and Antiferromagnetism in Topological Magnet MnBi2Te4 Films","authors":"Wei Yuan, Zi-Jie Yan, Hemian Yi, Zihao Wang, Stephen Paolini, Yi-Fan Zhao, Lingjie Zhou, Annie G. Wang, Ke Wang, Thomas Prokscha, Zaher Salman, Andreas Suter, Purnima P. Balakrishnan, Alexander J. Grutter, Laurel E. Winter, John Singleton, Moses H. W. Chan and Cui-Zu Chang*, ","doi":"10.1021/acs.nanolett.4c01407","DOIUrl":"10.1021/acs.nanolett.4c01407","url":null,"abstract":"<p >The interface of two materials can harbor unexpected emergent phenomena. One example is interface-induced superconductivity. In this work, we employ molecular beam epitaxy to grow a series of heterostructures formed by stacking together two nonsuperconducting antiferromagnetic materials, an intrinsic antiferromagnetic topological insulator MnBi<sub>2</sub>Te<sub>4</sub> and an antiferromagnetic iron chalcogenide FeTe. Our electrical transport measurements reveal interface-induced superconductivity in these heterostructures. By performing scanning tunneling microscopy and spectroscopy measurements, we observe a proximity-induced superconducting gap on the top surface of the MnBi<sub>2</sub>Te<sub>4</sub> layer, confirming the coexistence of superconductivity and antiferromagnetism in the MnBi<sub>2</sub>Te<sub>4</sub> layer. Our findings will advance the fundamental inquiries into the topological superconducting phase in hybrid devices and provide a promising platform for the exploration of chiral Majorana physics in MnBi<sub>2</sub>Te<sub>4</sub>-based heterostructures.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stacking orders provide a unique way to tune the properties of two-dimensional materials. Recently, ABCB-stacked tetralayer graphene has been predicted to possess atypical elemental ferroelectricity arising from its symmetry breaking but has been experimentally explored very little. Here, we observe pronounced nonlinear optical second-harmonic generation (SHG) in ABCB-stacked tetralayer graphene while absent in both ABAB- and ABCA-stacked allotropes. Our results provide direct evidence of symmetry breaking in ABCB-stacked tetralayer graphene. The remarkable contrast in the SHG spectra of tetralayer graphene allows straightforward identification of ABCB domains from the other two kinds of stacking order and facilitates the characterization of their crystalline orientation. The employed SHG technique serves as a convenient tool for exploring the intriguing physics and novel nonlinear optics in ABCB-stacked graphene, where spontaneous polarization and intrinsically gapped flat bands coexist. Our results establish ABCB-stacked graphene as a unique platform for studying the rare ferroelectricity in noncentrosymmetric elemental structures.
{"title":"Inversion Symmetry-Broken Tetralayer Graphene Probed by Second-Harmonic Generation.","authors":"Wenqiang Zhou, Jiannan Hua, Naitian Liu, Jing Ding, Hanxiao Xiang, Wei Zhu, Shuigang Xu","doi":"10.1021/acs.nanolett.4c01880","DOIUrl":"10.1021/acs.nanolett.4c01880","url":null,"abstract":"<p><p>Stacking orders provide a unique way to tune the properties of two-dimensional materials. Recently, ABCB-stacked tetralayer graphene has been predicted to possess atypical elemental ferroelectricity arising from its symmetry breaking but has been experimentally explored very little. Here, we observe pronounced nonlinear optical second-harmonic generation (SHG) in ABCB-stacked tetralayer graphene while absent in both ABAB- and ABCA-stacked allotropes. Our results provide direct evidence of symmetry breaking in ABCB-stacked tetralayer graphene. The remarkable contrast in the SHG spectra of tetralayer graphene allows straightforward identification of ABCB domains from the other two kinds of stacking order and facilitates the characterization of their crystalline orientation. The employed SHG technique serves as a convenient tool for exploring the intriguing physics and novel nonlinear optics in ABCB-stacked graphene, where spontaneous polarization and intrinsically gapped flat bands coexist. Our results establish ABCB-stacked graphene as a unique platform for studying the rare ferroelectricity in noncentrosymmetric elemental structures.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-17DOI: 10.1021/acs.nanolett.4c01250
Benjamin T. Diroll*, Corentin Dabard, Muchuan Hua, Juan I. Climente, Emmanuel Lhuillier and Sandrine Ithurria,
Concentric lateral CdSe/CdTe/CdSe heterostructures show bicolor photoluminescence from both a red charge transfer band of the CdSe/CdTe interface and a green fluorescence from CdSe. This work uses visible and near-infrared transient spectroscopy measurements to demonstrate that the deviation from Kasha’s rule arises from a hole relaxation bottleneck from CdSe to CdTe. Hole transfer can take up to 1 ns, which permits radiative relaxation of excitons remaining in CdSe. Simulations indicate that the hole relaxation bottleneck arises due to the sparse density of states and poor spatial overlap of hole states at energies near the CdSe band edge. The divergent kinetics of transfer for band edge and hot holes is exploited to vary the ratio of green and red photoluminescence with excitation wavelength, providing another knob to control emission color. These findings support the use of lateral heterojunctions as a method for slowing carrier relaxation in two-dimensional materials.
{"title":"Hole Relaxation Bottlenecks in CdSe/CdTe/CdSe Lateral Heterostructures Lead to Bicolor Emission","authors":"Benjamin T. Diroll*, Corentin Dabard, Muchuan Hua, Juan I. Climente, Emmanuel Lhuillier and Sandrine Ithurria, ","doi":"10.1021/acs.nanolett.4c01250","DOIUrl":"10.1021/acs.nanolett.4c01250","url":null,"abstract":"<p >Concentric lateral CdSe/CdTe/CdSe heterostructures show bicolor photoluminescence from both a red charge transfer band of the CdSe/CdTe interface and a green fluorescence from CdSe. This work uses visible and near-infrared transient spectroscopy measurements to demonstrate that the deviation from Kasha’s rule arises from a hole relaxation bottleneck from CdSe to CdTe. Hole transfer can take up to 1 ns, which permits radiative relaxation of excitons remaining in CdSe. Simulations indicate that the hole relaxation bottleneck arises due to the sparse density of states and poor spatial overlap of hole states at energies near the CdSe band edge. The divergent kinetics of transfer for band edge and hot holes is exploited to vary the ratio of green and red photoluminescence with excitation wavelength, providing another knob to control emission color. These findings support the use of <i>lateral</i> heterojunctions as a method for slowing carrier relaxation in two-dimensional materials.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1021/acs.nanolett.4c01392
Jeongmin Hwang, Jasper Wilson Dittmar, Janice Kang, Tonatiuh Ocampo, Michael Evangelopoulos, Zhenyu Han, Sergej Kudruk, Jochen Lorch* and Chad A. Mirkin*,
Vaccination for cancers arising from human papillomavirus (HPV) infection holds immense potential, yet clinical success has been elusive. Herein, we describe vaccination studies involving spherical nucleic acids (SNAs) incorporating a CpG adjuvant and a peptide antigen (E711–19) from the HPV-E7 oncoprotein. Administering the vaccine to humanized mice induced immunity-dependent on the oligonucleotide anchor chemistry (cholesterol vs (C12)9). SNAs containing a (C12)9-anchor enhanced IFN-γ production >200-fold, doubled memory CD8+ T-cell formation, and delivered more than twice the amount of oligonucleotide to lymph nodes in vivo compared to a simple admixture. Importantly, the analogous construct with a weaker cholesterol anchor performed similar to admix. Moreover, (C12)9-SNAs activated 50% more dendritic cells and generated T-cells cytotoxic toward an HPV+ cancer cell line, UM-SCC-104, with near 2-fold greater efficiency. These observations highlight the pivotal role of structural design, and specifically oligonucleotide anchoring strength (which correlates with overall construct stability), in developing efficacious therapeutic vaccines.
针对人类乳头瘤病毒(HPV)感染引起的癌症的疫苗接种具有巨大的潜力,但临床上一直未能取得成功。在此,我们介绍了结合了 CpG 佐剂和 HPV-E7 肿瘤蛋白多肽抗原(E711-19)的球形核酸(SNA)疫苗接种研究。给人源化小鼠注射疫苗后,其免疫力取决于寡核苷酸锚化学成分(胆固醇与 (C12)9)。与简单混合相比,含有 (C12)9 锚的 SNA 可使 IFN-γ 生成量提高 200 倍以上,使记忆 CD8+ T 细胞的形成增加一倍,并将两倍多的寡核苷酸输送到体内淋巴结。重要的是,胆固醇锚较弱的类似构建物与掺杂物的表现相似。此外,(C12)9-SNA 激活的树突状细胞增加了 50%,产生的 T 细胞对 HPV+ 癌细胞系 UM-SCC-104 具有细胞毒性,效率提高了近 2 倍。这些观察结果凸显了结构设计,特别是寡核苷酸锚定强度(与整体结构稳定性相关)在开发有效治疗疫苗中的关键作用。
{"title":"DNA Anchoring Strength Directly Correlates with Spherical Nucleic Acid–Based HPV E7 Cancer Vaccine Potency","authors":"Jeongmin Hwang, Jasper Wilson Dittmar, Janice Kang, Tonatiuh Ocampo, Michael Evangelopoulos, Zhenyu Han, Sergej Kudruk, Jochen Lorch* and Chad A. Mirkin*, ","doi":"10.1021/acs.nanolett.4c01392","DOIUrl":"10.1021/acs.nanolett.4c01392","url":null,"abstract":"<p >Vaccination for cancers arising from human papillomavirus (HPV) infection holds immense potential, yet clinical success has been elusive. Herein, we describe vaccination studies involving spherical nucleic acids (SNAs) incorporating a CpG adjuvant and a peptide antigen (E7<sub>11–19</sub>) from the HPV-E7 oncoprotein. Administering the vaccine to humanized mice induced immunity-dependent on the oligonucleotide anchor chemistry (cholesterol vs (C12)<sub>9</sub>). SNAs containing a (C12)<sub>9</sub>-anchor enhanced IFN-γ production >200-fold, doubled memory CD8<sup>+</sup> T-cell formation, and delivered more than twice the amount of oligonucleotide to lymph nodes <i>in vivo</i> compared to a simple admixture. Importantly, the analogous construct with a weaker cholesterol anchor performed similar to admix. Moreover, (C12)<sub>9</sub>-SNAs activated 50% more dendritic cells and generated T-cells cytotoxic toward an HPV<sup>+</sup> cancer cell line, UM-SCC-104, with near 2-fold greater efficiency. These observations highlight the pivotal role of structural design, and specifically oligonucleotide anchoring strength (which correlates with overall construct stability), in developing efficacious therapeutic vaccines.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141316011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}