Polycarbonate Heat Molding for Soft LithographySonmez, Utku M.; Coyle, Stephen; Taylor, Rebecca E.; LeDuc, Philip R.
doi: 10.1002/smll.202000241pmid: 32227442
Soft lithography enables rapid microfabrication of many types of microsystems by replica molding elastomers into master molds. However, master molds can be very costly, hard to fabricate, vulnerable to damage, and have limited casting life. Here, an approach for the multiplication of master molds into monolithic thermoplastic sheets for further soft lithographic fabrication is introduced. The technique is tested with master molds fabricated through photolithography, mechanical micromilling as well as 3D printing, and the results are demonstrated. Microstructures with submicron feature sizes and high aspect ratios are successfully copied. The copying fidelity of the technique is quantitatively characterized and the microfluidic devices fabricated through this technique are functionally tested. This approach is also used to combine different master molds with up to 19 unique geometries into a single monolithic copy mold in a single step displaying the effectiveness of the copying technique over a large footprint area to scale up the microfabrication. This microfabrication technique can be performed outside the cleanroom without using any sophisticated equipment, suggesting a simple way for high‐throughput rigid monolithic mold fabrication that can be used in analytical chemistry studies, biomedical research, and microelectromechanical systems.
Dynamic Environmental Control in Microfluidic Single‐Cell Cultivations: From Concepts to ApplicationsTäuber, Sarah; Lieres, Eric; Grünberger, Alexander
doi: 10.1002/smll.201906670pmid: 32157796
Microfluidic single‐cell cultivation (MSCC) is an emerging field within fundamental as well as applied biology. During the last years, most MSCCs were performed at constant environmental conditions. Recently, MSCC at oscillating and dynamic environmental conditions has started to gain significant interest in the research community for the investigation of cellular behavior. Herein, an overview of this topic is given and microfluidic concepts that enable oscillating and dynamic control of environmental conditions with a focus on medium conditions are discussed, and their application in single‐cell research for the cultivation of both mammalian and microbial cell systems is demonstrated. Furthermore, perspectives for performing MSCC at complex dynamic environmental profiles of single parameters and multiparameters (e.g., pH and O2) in amplitude and time are discussed. The technical progress in this field provides completely new experimental approaches and lays the foundation for systematic analysis of cellular metabolism at fluctuating environments.
Wearable Textile‐Based Co−Zn Alkaline Microbattery with High Energy Density and Excellent ReliabilityWang, Yao; Hong, Xufeng; Guo, Yaqing; Zhao, Yunlong; Liao, Xiaobin; Liu, Xiong; Li, Qi; He, Liang; Mai, Liqiang
doi: 10.1002/smll.202000293pmid: 32196919
Wearable in‐plane Zn‐based microbatteries are considered as promising micropower sources for wearable electronics due to their high capacity, low cost, high safety, and easy integration. However, their applications are severely impeded by inadequate energy density arising from unsatisfactory capacity of cathode and poor cycling stability caused by degradation of electrode materials and Zn dendrite. Additionally, the short‐circuit induced safety issue caused by Zn dendrite is still a roadblock for Zn‐based microbatteries. Herein, a textile‐based Co−Zn microbattery with ultrahigh energy density and excellent cycling stability is demonstrated. Benefiting from the fast electron transport of three‐dimensional (3D) porous Ni‐coated textile and synergistic effect from the hierarchical Co(OH)2@NiCo layered double hydroxide (LDH) core−shell electrode, the fabricated Co−Zn microbattery with high flexibility delivers superior energy/power densities of 0.17 mWh cm−2/14.4 mW cm−2, outperforming most reported micro energy storage devices. Besides, the trench‐type configuration as well as the 3D porous Zn@carbon clothes can avoid the short‐circuit‐induced safety issues, resulting in excellent cycling stability (71% after 800 cycles). The unique core−shell structure and novel configuration provide a brand‐new design strategy for high‐performance wearable in‐plane microdevices.
A Versatile Toolkit for Controllable and Highly Selective Multifunctionalization of Bacterial Magnetic NanoparticlesMickoleit, Frank; Lanzloth, Clarissa; Schüler, Dirk
doi: 10.1002/smll.201906922pmid: 32187836
Their unique material characteristics, i.e. high crystallinity, strong magnetization, uniform shape and size, and the ability to engineer the enveloping membrane in vivo make bacterial magnetosomes highly interesting for many biomedical and biotechnological applications. In this study, a versatile toolkit is developed for the multifunctionalization of magnetic nanoparticles in the magnetotactic bacterium Magnetospirillum gryphiswaldense, and the use of several abundant magnetosome membrane proteins as anchors for functional moieties is explored. High‐level magnetosome display of cargo proteins enables the generation of engineered nanoparticles with several genetically encoded functionalities, including a core–shell structure, magnetization, two different catalytic activities, fluorescence and the presence of a versatile connector that allows the incorporation into a hydrogel‐based matrix by specific coupling reactions. The resulting reusable magnetic composite demonstrates the high potential of synthetic biology for the production of multifunctional nanomaterials, turning the magnetosome surface into a platform for specific versatile display of functional moieties.
Isostructural and Multivalent Anion Substitution toward Improved Phosphate Cathode Materials for Sodium‐Ion BatteriesWang, Mei‐Yi; Guo, Jin‐Zhi; Wang, Zhi‐Wei; Gu, Zhen‐Yi; Nie, Xue‐Jiao; Yang, Xu; Wu, Xing‐Long
doi: 10.1002/smll.201907645pmid: 32141157
Polyanion‐type phosphate materials are highly promising cathode candidates for next‐generation batteries due to their excellent structural stability during cycling; however, their poor conductivity has impeded their development. Isostructural and multivalent anion substitution combined with carbon coating is proposed to greatly improve the electrochemical properties of phosphate cathode in sodium‐ion batteries (SIBs). Specifically, multivalent tetrahedral SiO44− substitute for PO43− in Na3V2(PO4)3 (NVP) lattice, preparing the optimal Na3.1V2(PO4)2.9(SiO4)0.1 with high‐rate capability (delivering a high capacity of 82.5 mAh g−1 even at 20 C) and outstanding cyclic stability (≈98% capacity retention after 500 cycles at 1 C). Theoretical calculation and experimental analyses reveal that the anion‐substituted Na3.1V2(PO4)2.9(SiO4)0.1 reduces the bandgap of NVP lattice and enhanced its structural stability, Na+‐diffusion kinetics and electronic conductivity. This strategy of multivalent and isostructural anion substitution chemistry provides a new insight to develop advanced phosphate cathodes.
Self‐Therapeutic Nanoparticle That Alters Tau Protein and Ameliorates Tauopathy Toward a Functional Nanomedicine to Tackle Alzheimer'sVimal, Sunil Kumar; Zuo, Hua; Wang, Zhengwu; Wang, Hongrun; Long, Zhiliang; Bhattacharyya, Sanjib
doi: 10.1002/smll.201906861pmid: 32191383
Tauopathy is a complex disorder associated at the junction of several other pathologies. Intrinsically disordered tau protein remains therapeutically challenging due to its undruggable nature and is a possible reason for monumental failure of several tau‐based therapies. Herein, nanogold remodeled tau is reported as a pseudo‐nanochaperon and shows therapeutic benefit by passive targeting in transgenic tau P301L mutant mice. Treatment with nanogold polyethylene glycol (Au‐PEG) conjugate moderately improves the learning ability of the tau P301L mice that corroborates with diminished phosphorylated tau burden. Circulating total tau level that acts in a prion fashion is significantly reduced upon Au‐PEG treatment. Similarly, a high level of tau is found in macaque monkey serum and Au‐PEG inhibits amyloidosis of Alzheimer's patients and primate's serum samples ex vivo. Addtionally, brain MRI of an old aged macaque monkey shows the decrease of grey matter, which correlates with mutual loss of grey matter upon progressive dementia as reported. Au‐PEG tunes tau and other circulating pro‐dementia factors that are present in human AD serum, by remodeling the protein and repairing aberrant proteostasis. Alteration of proteotoxic tau function by nanogold as a kinetic stablizer holds translational potential to combat socially challenging dementia.
Structural Color Materials for Optical AnticounterfeitingHong, Wei; Yuan, Zhongke; Chen, Xudong
doi: 10.1002/smll.201907626pmid: 32187853
The counterfeiting of goods is growing worldwide, affecting practically any marketable item ranging from consumer goods to human health. Anticounterfeiting is essential for authentication, currency, and security. Anticounterfeiting tags based on structural color materials have enjoyed worldwide and long‐term commercial success due to their inexpensive production and exceptional ease of percept. However, conventional anticounterfeiting tags of holographic gratings can be readily copied or imitated. Much progress has been made recently to overcome this limitation by employing sufficient complexity and stimuli‐responsive ability into the structural color materials. Moreover, traditional processing methods of structural color tags are mainly based on photolithography and nanoimprinting, while new processing methods such as the inkless printing and additive manufacturing have been developed, enabling massive scale up fabrication of novel structural color security engineering. This review presents recent breakthroughs in structural color materials, and their applications in optical encryption and anticounterfeiting are discussed in detail. Special attention is given to the unique structures for optical anticounterfeiting techniques and their optical aspects for encryption. Finally, emerging research directions and current challenges in optical encryption technologies using structural color materials is presented.