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Feb 02, 2022

Volume 5Issue 2p365-762
On the cover: As reported by Y.S. Zhang and colleagues in this issue of Matter, a cryobioprinting method is optimized for fabricating freeform storable tissue constructs with shelf availability by taking advantage of the designed cryoprotective bioinks to maintain the functionality of embedded cells during the cryobioprinting and cryostorage processes....
On the cover: As reported by Y.S. Zhang and colleagues in this issue of Matter, a cryobioprinting method is optimized for fabricating freeform storable tissue constructs with shelf availability by taking advantage of the designed cryoprotective bioinks to maintain the functionality of embedded cells during the cryobioprinting and cryostorage processes.


  • If everyone is an impostor in academia, then no one is

    • Steve Cranford
    One of my earliest manifestations of impostor syndrome was when I was just about to take the Graduate Record Examination (GRE). Merits of the exam aside, it was required at the time for most of my targeted grad schools in the USA. In Canada, however, one was not exposed to standardized testing such as the SATs, so preparation for such an exam was a new experience for me, along with the related stresses. I figured for sure, while I had decent grades in undergraduate, the GRE would expose me as exceptionally average.

Matter of Opinions

  • Enhancing humans and machines with ubiquitous electroadhesives

    • Jianglong Guo,
    • Jinsong Leng,
    • Jonathan Rossiter
    Electroadhesion technologies empower devices with controllable adhesion and have distinctive benefits, compared to other alternatives, including increased adaptability, reduced complexity, low energy consumption, and comfortable interaction capabilities. Here, we discuss how electroadhesives can be exploited to augment functionalities of humans and machines, and enhance the growing connections between them.
  • On the controversial role of earthquake triggering of the Rigopiano avalanche

    • Nicola M. Pugno
    Here Nicola Pugno, leading expert in fracture mechanics, deduces by sticking to the facts that (1) there is no evidence of earthquake triggering of the Rigopiano avalanche, (2) earthquake triggering of this avalanche is very unlikely, (3) even if it cannot be proved nor disproved, (4) those earthquakes are equivalent to only a few centimeters of snow precipitation, and (5) even assuming earthquake triggering, the avalanche would have likely occurred the very same day even in absence of earthquakes.


  • An innovative synthesis strategy for high-efficiency and defects-switchable-hydrogenated TiO2 photocatalysts

    • Guangfu Liao,
    • Xiaoyu Tao,
    • Baizeng Fang
    Hydrogenated TiO2 (H-TiO2) is one of the most promising TiO2-based photocatalysts. Through effectively narrowing the band gap of TiO2 and restraining the recombination of photogenerated carriers, in the January issue of Matter, Cui et al. reported a new and facile one-pot wet-chemistry strategy to prepare H-TiO2 for highly efficient photocatalytic hydrogen (H2) evolution.1
  • Liquid metals empower energy-efficient flow reactors

    • Kanudha Sharda
    Innovative ways to grow atomically thin materials are constantly evolving, and these methods have the potential to overcome several practical issues that could hinder the growth of high-quality material in an energy-efficient way. In the December 2021 issue of Matter, Han, Kalantar-Zadeh, and colleagues have published another proof-of-concept study to synthesize Mn3O4, MoS2, and reduced graphene oxide within a large portfolio of materials, assisted via a gallium-based liquid metal technique that enabled an energy-efficient continuous flow reactor system.
  • Bridging MXene layers for strong multifunctional films

    • Yury Gogotsi
    In a recent work in Science, Cheng’s group at Beihang University demonstrated strong and tough MXene films with excellent conductivity, environmental stability, and electromagnetic interference shielding. Sequential bridging of 2D MXene sheets with sodium carboxymethyl cellulose and borate ions produced multifunctional composites.
  • Monodispersed perovskite quantum wells for efficient LEDs

    • Atanu Jana,
    • Sunjung Park,
    • Sangeun Cho,
    • Hyungsang Kim,
    • Hyunsik Im
    The ability to fabricate monodisperse reduced-dimensional perovskite (RDP) films would enable researchers to further understand and apply RDP films in various optoelectronic applications. Nature recently published a study by Ma et al. where monodisperse RDP was fabricated using a bifunctional molecular additive. The monodisperse-RDP-based LED achieved an external quantum efficiency of 25.6% with an exceptional half-life at an initial luminance of 7,200 cd m−2.
  • Supramolecular polymer networks with high compressibility and fast self-recovery

    • Zhe Gao,
    • Hongjiang Wang,
    • Zhao Chen
    Highly compressible supramolecular polymer networks are highly desirable but are seldom reported. In a recent work published in Nature Materials by Scherman et al., glass-like high-performance supramolecular polymer networks are successfully developed by means of slow-dissociative non-covalent cross-linkers. The resulting supramolecular polymer networks demonstrate superior compressive strength of up to 100 MPa and a rapid room-temperature self-recovery (<120 s).


  • Bioinspired microneedle patches: Biomimetic designs, fabrication, and biomedical applications

    • Pooyan Makvandi,
    • Aziz Maleki,
    • Majid Shabani,
    • Aaron R.J. Hutton,
    • Melissa Kirkby,
    • Rezvan Jamaledin,
    • Tianxu Fang,
    • Jiahuan He,
    • Jesse Lee,
    • Barbara Mazzolai,
    • Ryan F. Donnelly,
    • Franklin R. Tay,
    • Guojun Chen,
    • Virgilio Mattoli
    Nature contains abundant systems that can significantly alter their structures and properties to adapt to the surrounding environment. Through natural selection and unceasing evolution, hierarchical architectures and sophisticated strategies have been created by nature to achieve optimally adapted materials for biomedical applications. The development of MNs has advanced to the next generation of BMNs, with the goal of improving functions such as amelioration of mechanical properties and tissue adhesion. The biomimetic designs and structures of MNs are highlighted in the present review. This is followed by an in-depth discussion of the fabrication approaches from molding techniques to 3D and 4D printing. The medical applications of BMNs, including drug delivery, regenerative medicine, biopsy sampling, and biosensing, are also discussed. Last, future opportunities and challenges with respect to clinical translation are also deliberated.
  • Upgrading carbonaceous materials: Coal, tar, pitch, and beyond

    • Xining Zang,
    • Yuan Dong,
    • Cuiying Jian,
    • Nicola Ferralis,
    • Jeffrey C. Grossman
    The perspective highlights the shift of coal and other heavy carbonaceous materials (tar, pitch, and beyond) from combustion sources to low carbon emission applications ranging from joule heaters, supercapacitors, and strain sensors. Laser annealing and molecular dynamics simulations can guide the thermal upgrading of these materials, and machine learning methods can potentially enable efficient and flexible continuous manufacturing processes. HCM-based devices could be produced at large scale and ultra-low cost, making them appealing for integration with large volume applications such as construction and infrastructure.
  • Carbon nanotubes in perovskite-based optoelectronic devices

    • Zijing Dong,
    • Weiping Li,
    • Hailiang Wang,
    • Xiaoyu Jiang,
    • Huicong Liu,
    • Liqun Zhu,
    • Haining Chen
    Halide perovskites have been widely utilized as a light-absorbing layer in a wide range of optoelectronic devices. Incorporating carbon nanotubes (CNTs) into perovskite-based devices has important roles in enhancing device performance. Here, we systematically review the effect of CNT incorporation on the performance of perovskite solar cells, photodetectors, and light-emitting-diodes, in which CNTs could serve as a conducting substrate, charge selection electrode, additive in different components, interface layer, and so on.
  • Progress and potential for symmetrical solid oxide electrolysis cells

    • Yunfeng Tian,
    • Nalluri Abhishek,
    • Caichen Yang,
    • Rui Yang,
    • Sihyuk Choi,
    • Bo Chi,
    • Jian Pu,
    • Yihan Ling,
    • John T.S. Irvine,
    • Guntae Kim
    Symmetrical solid oxide electrolysis cells with the same electrode materials as both the anode and cathode have attracted lots of attention because of their simple manufacturing process and low cost. However, there has not been a comprehensive and critical review to summarize the recent progress so far. This review gives a comprehensive overview of their development history, fundamental mechanisms, electrolyte and electrode materials, and applications. We share our perspectives on the remaining challenges and potential solutions for driving this emerging field forward.
  • Beyond sonication: Advanced exfoliation methods for scalable production of 2D materials

    • Weiran Zheng,
    • Lawrence Yoon Suk Lee
    Two-dimensional (2D) materials show superiority over bulk counterparts in various fields, from electronics to catalysis. To maximize the advantages of 2D materials, their scalable production is urgently desired. In this review, the scalability of production methods of 2D materials is first examined from the point of the quality-quantity trade-off. The principles, recent progress made, and the pros and cons of the mechanical, hydrothermal, electrochemical, laser-assisted, and microwave-assisted exfoliations are discussed, with a comprehensive analysis of their scalability in six aspects.
  • Recent advances in niobium MXenes: Synthesis, properties, and emerging applications

    • P. Abdul Rasheed,
    • Ravi P. Pandey,
    • Fawzi Banat,
    • Shadi W. Hasan
    Recently, niobium-based MXenes, such as Nb2CTx and Nb4C3Tx, have emerged as attractive materials for various applications because of their unique properties and potential applications. In this review, synthesis methods and current advances in the use of niobium MXenes for energy, biomedical, laser, electromagnetic, and microwave shielding applications, among others, are discussed. Conclusions and future prospects for maximizing the effectiveness of MXenes for a variety of practical applications are also highlighted.


  • Freeform cell-laden cryobioprinting for shelf-ready tissue fabrication and storage

    • Hossein Ravanbakhsh,
    • Zeyu Luo,
    • Xiang Zhang,
    • Sushila Maharjan,
    • Hengameh S. Mirkarimi,
    • Guosheng Tang,
    • Carolina Chávez-Madero,
    • Luc Mongeau,
    • Yu Shrike Zhang
    Cryobioprinting potentially empowers the acceleration of the transition of biofabricated artificial tissue constructs from research labs to clinics. The method helps bioengineers to fabricate cell-laden tissue constructs and store them for extended periods of time. This feature adds more flexibility in shelf availability of biofabricated tissue constructs. The test samples were bioprinted using GelMA-based hydrogels, CPAs, and various human cells. Our findings showed that the cells remained viable and functional after 3 months of cryobioprinting and cryopreservation in liquid nitrogen.
  • Ultrafast high-temperature sintering to avoid metal loss toward high-performance and scalable cermets

    • Miao Guo,
    • Qi Dong,
    • Hua Xie,
    • Chengwei Wang,
    • Yunhao Zhao,
    • Xizheng Wang,
    • Wei Zhong,
    • Zhihan Li,
    • Ruiliu Wang,
    • Yuankang Wang,
    • Liangyan Hao,
    • Shuaiming He,
    • Gang Chen,
    • Wei Xiong,
    • Ji-Cheng Zhao,
    • Liangbing Hu
    Cermet sintering faces many challenges, such as metal volatilization, grain coarsening, and poor wettability of metal with the ceramic phase. In this work, we apply an ultrafast high-temperature sintering (UHS) method to sinter high-quality cermets in only seconds. The high temperature leads to good wettability of metal with the ceramic phase, while the short sintering time limits the loss of metal components as well as accurately controlling the grain growth.
  • Novel meta-phase arising from large atomic size mismatch

    • Kunpeng Zhao,
    • Chenxi Zhu,
    • Wujie Qiu,
    • Shiqi Yang,
    • Hong Su,
    • Pengfei Qiu,
    • Ying He,
    • Mengjia Guan,
    • Tian-Ran Wei,
    • Jie Ma,
    • Jue Liu,
    • Guanhaojie Zheng,
    • Fangfang Xu,
    • Xun Shi,
    • Jian He,
    • Lidong Chen
    We discovered a single-phased novel state of matter—the meta-phase—in Cu2(S,Te), Ag2(S,Te), and Mg2(Si,Sn) over a wide composition and temperature range. Counterintuitively, the meta-phase formation entails a large atomic size mismatch between anions and a large diffusion coefficient mismatch between cations and anions, leading to exquisite atomic structures and ensuing interesting physicochemical properties.
  • Chemical design of self-propelled Janus droplets

    • Caleb H. Meredith,
    • Alexander C. Castonguay,
    • Yu-Jen Chiu,
    • Allan M. Brooks,
    • Pepijn G. Moerman,
    • Peter Torab,
    • Pak Kin Wong,
    • Ayusman Sen,
    • Darrell Velegol,
    • Lauren D. Zarzar
    Self-propelling droplets comprise a rich chemical platform for the exploration of active matter, but isotropic droplets rely on spontaneous symmetry breaking to sustain motion. We uncover the chemomechanical framework underlying the self-propulsion of biphasic Janus oil droplets solubilizing in aqueous surfactant. Our findings elucidate the pivotal role of oil partitioning between Janus droplet compartments in determining droplet swimming speed and direction, providing insights as to how the chemistry and structure of multiphase fluids can be harnessed to design programmable microswimmers.
  • Continuously growing multi-layered hydrogel structures with seamless interlocked interface

    • Rongnian Xu,
    • Mutian Hua,
    • Shuwang Wu,
    • Shuanhong Ma,
    • Yunlei Zhang,
    • Liqiang Zhang,
    • Bo Yu,
    • Meirong Cai,
    • Ximin He,
    • Feng Zhou
    Herein, a method, namely, ultraviolet-triggered surface catalytically initiated radical polymerization (UV-SCIRP), is reported for preparing layered structural hydrogels with a living polymerization growing process resembling the growth route of natural bio-tissues, in which Fe2+ ions were generated in situ from the surface-bound Fe3+ ions of a hydrogel substrate to catalyze radical polymerization at the solid-liquid interface to grow hydrogel layers at room temperature. The versatile method is effective in constructing complex hydrogel patterns and arbitrarily shaped layered hydrogel architectures.
  • High-throughput experiments for rare-event rupture of materials

    • Yifan Zhou,
    • Xuhui Zhang,
    • Meng Yang,
    • Yudong Pan,
    • Zhenjiang Du,
    • Jose Blanchet,
    • Zhigang Suo,
    • Tongqing Lu
    We develop a high-throughput experiment to study rare-event rupture. In a high-throughput experiment, we fabricate 1,000 samples, stretch them simultaneously, and identify rupture of individual samples. The data are analyzed statistically. The high-throughput experiment increases efficiency and enables the prediction of rare events.
  • Immunomodulatory microneedle patch for periodontal tissue regeneration

    • Xuexiang Zhang,
    • Mohammad Mahdi Hasani-Sadrabadi,
    • Jana Zarubova,
    • Erfan Dashtimighadam,
    • Reihaneh Haghniaz,
    • Ali Khademhosseini,
    • Manish J. Butte,
    • Alireza Moshaverinia,
    • Tara Aghaloo,
    • Song Li
    Periodontitis is a chronic inflammatory disease causing the degeneration of tooth-supporting tissues in humans. Besides bacterial infection, destructive immune cells play a critical role in the tissue loss. To address the challenge of drug delivery in oral cavity and achieve periodontal tissue regeneration, we engineer an immunomodulatory microneedle patch to enable minimally invasive tissue penetration and local retention for sustained delivery of antibiotics and cytokines that promotes pro-regenerative signals locally.
  • Chemo-thermal surface dedoping for high-performance tin perovskite solar cells

    • Jianheng Zhou,
    • Mingwei Hao,
    • Yu Zhang,
    • Xue Ma,
    • Jianchao Dong,
    • Feifei Lu,
    • Jie Wang,
    • Ning Wang,
    • Yuanyuan Zhou
    The detrimental self-doping due to Sn(II)-to-Sn(IV) oxidation remains a hurdle in the development of high-performance Pb-free Sn perovskite solar cells. A chemo-thermal dedoping process is therefore introduced to reduce the Sn(IV) self-dopants on the film surface. This process is enabled by organic-inorganic complexation between the FACl and Sn(IV) iodide components in perovskite, which facilitates Sn(IV) removal upon thermal annealing. The resultant Sn perovskite solar cells can show PCEs up to 14.7% as well as good device stability.
  • Identifying infectiousness of SARS-CoV-2 by ultra-sensitive SnS2 SERS biosensors with capillary effect

    • Yusi Peng,
    • Chenglong Lin,
    • Yanyan Li,
    • Yong Gao,
    • Jing Wang,
    • Jun He,
    • Zhengren Huang,
    • Jianjun Liu,
    • Xiaoying Luo,
    • Yong Yang
    Motivated by the synergistic contribution of the molecular enrichment caused by capillary effect and the chemical enhancement boosted by lattice strain and sulfur vacancies, the developed ultra-sensitive SnS2 hierarchical nanostructure SERS substrates exhibit an extremely low limit of detection of 10−13 M, which can be applied to complete the identification of infectiousness for SARS-CoV-2 samples, whereas the current PCR methods cannot.
  • Why mussel byssal plaques are tiny yet strong in attachment

    • Daanish Aleem Qureshi,
    • Stephen Goffredo,
    • Yongtae Kim,
    • Yulong Han,
    • Ming Guo,
    • Seunghwa Ryu,
    • Zhao Qin
    Blue mussels can face large tidal impact forces in the ocean and hang in place. Their capability is enabled by producing byssal threads that end with a single adhesive plaque, which allows them to attach to various substrates. Investigating this attachment mechanism and its optimization will help understand design principles found in nature, thereby shedding light on designing reinforcement systems to better secure engineering structures.
  • Achieving high efficiency and well-kept ductility in ternary all-polymer organic photovoltaic blends thanks to two well miscible donors

    • Ruijie Ma,
    • Kangkang Zhou,
    • Yanna Sun,
    • Tao Liu,
    • Yuanyuan Kan,
    • Yiqun Xiao,
    • Top Archie Dela Peña,
    • Yixin Li,
    • Xinhui Zou,
    • Zengshan Xing,
    • Zhenghui Luo,
    • Kam Sing Wong,
    • Xinhui Lu,
    • Long Ye,
    • He Yan,
    • Ke Gao
    This work builds a high-efficiency ternary all-polymer solar cell and pays attention to the change of film ductility. The structure-property relationship based on efficiency, morphological parameters, and the film's mechanical property is demonstrated.
  • Dynamically preferred state with strong electronic fluctuations from electrochemical synthesis of sodium manganate

    • Xi Chen,
    • Yichao Wang,
    • Yiping Wang,
    • Rebecca L. Dally,
    • Kamila Wiaderek,
    • Tianyu Qiao,
    • Jue Liu,
    • Enyuan Hu,
    • Kenneth Burch,
    • Jeffrey W. Lynn,
    • Xin Li
    Electrochemical (de)intercalation is a delicate method to precisely control the composition and possible orderings of alkaline ions in alkaline transition metal oxides. Electrochemically prepared Na1/2MnO2 ordering exhibits abnormal structure distortions, charge orderings, and dynamic activities. Strong magnetic fluctuations and lattice dynamics are observed in an unusually wide temperature range, mediated through the unique charge flux oscillation. Our findings provide a new paradigm to understand how lattice dynamics can contribute to spin fluctuations through charge flux functionals on top of charge density functionals.
  • Iron corrosion in the “inert” supercritical CO2, ab initio dynamics insights: How impurities matter

    • Qin-Kun Li,
    • Alex Kutana,
    • Evgeni S. Penev,
    • Boris I. Yakobson
    The corrosion of iron by supercritical carbon dioxide (sCO2) is studied using first-principles molecular dynamics at the atomic scale. The iron surface is found to play a crucial role in its own corrosion, activating the inert CO2 and hence facilitating the creation of reactive species at the iron | sCO2 interface. When present, water forms a hydrogen bond network that assists H shuttling to the activated sCO2 and impurities, forming reactive species observed in experiments.