Titanium Dioxide Nanomaterials for Sensor Applications

Nanostructures: Synthesis, Assembly, and Their Applications in Electrochemistry Chengzhou Zhu,† Dan Du,†,⊥ Alexander Eychmüller,‡ and Yuehe Lin*,†,§ †School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164-2920, United States Key Laboratory of Pesticide and Chemical Biology of the Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China ‡Physical Chemistry, TU Dresden, Bergstrasse 66b, 01062 Dresden, Germany Pacific Northwest National Laboratory, Richland, Washington 99352, United States

Engineering Ordered and Nonordered Porous Noble Metal Nanostructures: Synthesis, Assembly, and Their Applications in Electrochemistry

■ CONTENTS Novel ECL Systems 358 Novel Organic Luminophores 358 Novel Inorganic Luminophores 359 Novel Nanomaterial System 360 Detection Methodologies and Signaling Amplification Strategies 361 General Detection Methodologies 361 Novel Signal Amplification Strategies 361 ECL Applications 362 Metal Ions Detection 362 Small Molecules Detection 362 ECL Immunoassay 363 ECL Genosensors 365 ECL Cytosensors 366 Conclusions and Outlooks 368 Author Information 369 Corresponding Author 369 ORCID 369 Author Contributions 369 Notes 369 Biographies 369 Acknowledgments 369 References 369

Recent Advances in Electrochemiluminescence Analysis.

A fundamental feature of cellular plasma membranes (PMs) is an asymmetric lipid distribution between the bilayer leaflets. However, neither the detailed, comprehensive compositions of individual PM leaflets nor how these contribute to structural membrane asymmetries have been defined. We report the distinct lipidomes and biophysical properties of both monolayers in living mammalian PMs. Phospholipid unsaturation is dramatically asymmetric, with the cytoplasmic leaflet being approximately twofold more unsaturated than the exoplasmic leaflet. Atomistic simulations and spectroscopy of leaflet-selective fluorescent probes reveal that the outer PM leaflet is more packed and less diffusive than the inner leaflet, with this biophysical asymmetry maintained in the endocytic system. The structural asymmetry of the PM is reflected in the asymmetric structures of protein transmembrane domains. These structural asymmetries are conserved throughout Eukaryota, suggesting fundamental cellular design principles.

Plasma membranes are asymmetric in lipid unsaturation, packing and protein shape.

Microfluidic devices have attracted increasing attention in the fields of biomedical diagnostics, food safety control, environmental protection, and animal epidemic prevention. Micromixing has a considerable impact on the efficiency and sensitivity of microfluidic devices. This work reviews recent advances on the passive and active micromixers for the development of various microfluidic chips. Recently reported active micromixers driven by pressure fields, electrical fields, sound fields, magnetic fields, and thermal fields, etc. and passive micromixers, which owned two-dimensional obstacles, unbalanced collisions, spiral and convergence-divergence structures or three-dimensional lamination and spiral structures, were summarized and discussed. The future trends for micromixers to combine with 3D printing and paper channel were brought forth as well.

A Review on Micromixers

The use of artificial cells has attracted considerable attention in various fields from biotechnology to medicine. Here, we develop a cell-sized vesicle-in-vesicle (VIV) structure containing a separate inner vesicle (IV) that can be loaded with DNA. We use polymerase chain reaction (PCR) to successfully amplify the amount of DNA confined to the IV. Subsequent osmotic stress-induced fission of a mother VIV into two daughter VIVs successfully divides the IV content while keeping it confined to the IV of the daughter VIVs. The fission rate was estimated to be ∼20% quantified by fluorescence microscope. Our VIV structure represents a step forward toward construction of an advanced, fissionable cell model.

A Fissionable Artificial Eukaryote-like Cell Model

Electroformation of giant unilamellar vesicles in saline solution.

Regulating the coordination environment of atomically dispersed catalysts is vital for catalytic reaction but still remains a challenge. Herein, an ionic exchange strategy is developed to fabricate atomically dispersed copper (Cu) catalysts with controllable coordination structure. In this process, the adsorbed Cu ions exchange with Zn nodes in ZIF-8 under high temperature, resulting in the trapping of Cu atoms within the cavities of the metal-organic framework, and thus forming Cu single-atom catalysts. More importantly, altering pyrolysis temperature can effectively control the structure of active metal center at atomic level. Specifically, higher treatment temperature (900 °C) leads to unsaturated Cu-nitrogen architecture (CuN3 moieties) in atomically dispersed Cu catalysts. Electrochemical test indicates atomically dispersed Cu catalysts with CuN3 moieties possess superior oxygen reduction reaction performance than that with higher Cu-nitrogen coordination number (CuN4 moieties), with a higher half-wave potential of 180 mV and the 10 times turnover frequency than that of CuN4 . Density functional theory calculation analysis further shows that the low N coordination number of Cu single-atom catalysts (CuN3 ) is favorable for the formation of O2 * intermediate, and thus boosts the oxygen reduction reaction.

Ionic Exchange of Metal-Organic Frameworks for Constructing Unsaturated Copper Single-Atom Catalysts for Boosting Oxygen Reduction Reaction.

Bio-hydrogen production from cornstalk wastes by orthogonal design method

In this work, the highly oriented CdS-coated-ZnO nanorod arrays have been fabricated. The CdS-coated-ZnO nanorod arrays show high electrochemiluminescence intensity, fast response and good stability. All of the desirable properties spur the development of an ECL immunosensor for the detection of the liver cancer cell line (HepG2 cells). Two successive modification steps of 3-aminopropyltriethoxysilane and gold nanoparticles onto the CdS-coated-ZnO nanorod arrays not only offer the substrates for conjugation of antibody, but also effectively enhance the ECL signal, resulting in production of the high performance ECL immunosensor. The ECL immunosensor exhibits a sensitive response to HepG2 cells in a linear range of 300–10 000 cells mL−1 with a detection limit of 256 cells mL−1. The proposed sensor characteristics of high specificity, good reproducibility and remarkable stability will provide a sensitive, selective, and convenient approach for the clinical detection of cancer cells.

Shenghua Ma

Papers

A Fissionable Artificial Eukaryote-like Cell Model

Electroformation of giant unilamellar vesicles in saline solution.

Ionic Exchange of Metal-Organic Frameworks for Constructing Unsaturated Copper Single-Atom Catalysts for Boosting Oxygen Reduction Reaction.

Bio-hydrogen production from cornstalk wastes by orthogonal design method

A novel electrochemiluminescent immunosensor based on CdS-coated ZnO nanorod arrays for HepG2 cell detection