Jiangjiexing Wu

DNA sequence-dependent morphological evolution of silver nanoparticles and their optical and hybridization properties.

A systematic investigation of the effects of different DNA sequences on the morphologies of silver nanoparticles (AgNPs) grown from Ag nanocube seeds is reported. The presence of 10-mer oligo-A, -T, and -C directed AgNPs growth from cubic seeds into edge-truncated octahedra of different truncation extents and truncated tetrahedral AgNPs, while AgNPs in the presence of oligo-G remained cubic. The shape and morphological evolution of the nanoparticle growth for each system is investigated using SEM and TEM and correlated with UV-vis absorption kinetic studies. In addition, the roles of oligo-C and oligo-G secondary structures in modulating the morphologies of AgNPs are elucidated, and the morphological evolution for each condition of AgNPs growth is proposed. The shapes were found to be highly dependent on the binding affinity of each of the bases and the DNA secondary structures, favoring the stabilization of the Ag{111} facet. The AgNPs synthesized through this method have morphologies and optical properties that can be varied by using different DNA sequences, while the DNA molecules on these AgNPs are also stable against glutathione. The AgNP functionalization can be realized in a one-step synthesis while retaining the biorecognition ability of the DNA, which allows for programmable assembly.

Monitoring of Heparin Activity in Live Rats Using Metal–Organic Framework Nanosheets as Peroxidase Mimics

Metal-organic framework (MOF) nanosheets are a class of two-dimensional (2D) porous and crystalline materials that hold promise for catalysis and biodetection. Although 2D MOF nanosheets have been utilized for in vitro assays, ways of engineering them into diagnostic tools for live animals are much less explored. In this work, a series of MOF nanosheets are successfully engineered into a highly sensitive and selective diagnostic platform for in vivo monitoring of heparin (Hep) activity. The iron-porphyrin derivative is selected as a ligand to synthesize a series of archetypical MOF nanosheets with intrinsic heme-like catalytic sites, mimicking peroxidase. Hep-specific AG73 peptides as recognition motifs are physically adsorbed onto MOF nanosheets, blocking active sites from nonspecific substrate-catalyst interaction. Because of the highly specific interaction between Hep and AG73, the activity of AG73-MOF nanosheets is restored upon the binding of Hep, but not Hep analogues and other endogenous biomolecules. Furthermore, by taking advantages of biocompatibility and diagnostic property enabled by AG73-MOF nanosheets, the elimination process of Hep in live rats is quantitatively monitored by coupling with microdialysis technology. This work expands the biomedical applications of 2D MOF nanomaterials and provides access to a promising in vivo diagnostic platform.

Nanozymes: Next Wave of Artificial Enzymes

This book describes the fundamental concepts, the latest developments and the outlook of the field of nanozymes (i.e., the catalytic nanomaterials with enzymatic characteristics). As one of today s most exciting fields, nanozyme research lies at the interface of chemistry, biology, materials science and nanotechnology. Each of the book s six chapters explores advances in nanozymes. Following an introduction to the rise of nanozymes research in the course of research on natural enzymes and artificial enzymes in Chapter 1, Chapters 2 through 5 discuss different nanomaterials used to mimic various natural enzymes, from carbon-based and metal-based nanomaterials to metal oxide-based nanomaterials and other nanomaterials. In each of these chapters, the nanomaterials enzyme mimetic activities, catalytic mechanisms and key applications are covered. In closing, Chapter 6 addresses the current challenges and outlines further directions for nanozymes. Presenting extensive information on nanozymes and supplemented with a wealth of color illustrations and tables, the book offers an ideal guide for readers from disparate areas, including analytical chemistry, materials science, nanoscience and nanotechnology, biomedical and clinical engineering, environmental science and engineering, green chemistry, and novel catalysis

Enhanced and tunable fluorescent quantum dots within a single crystal of protein

AbstractThe design and synthesis of bio-nano hybrid materials can not only provide new materials with novel properties, but also advance our fundamental understanding of interactions between biomolecules and their abiotic counterparts. Here, we report a new approach to achieving such a goal by growing CdS quantum dots (QDs) within single crystals of lysozyme protein. This bio-nano hybrid emitted much stronger red fluorescence than its counterpart without the crystal, and such fluorescence properties could be either enhanced or suppressed by the addition of Ag(I) or Hg(II), respectively. The three-dimensional incorporation of CdS QDs within the lysozyme crystals was revealed by scanning transmission electron microscopy with electron tomography. More importantly, since our approach did not disrupt the crystalline nature of the lysozyme crystals, the metal and protein interactions were able to be studied by X-ray crystallography, thus providing insight into the role of Cd(II) in the CdS QDs formation.

Integrated nanozymes: facile preparation and biomedical applications

Nanozymes have been viewed as the next generation of artificial enzymes due to their low cost, large specific surface area, and good robustness under extreme conditions. However, the moderate activity and limited selectivity of nanozymes have impeded their usage. To overcome these shortcomings, integrated nanozymes (INAzymes) have been developed by encapsulating two or more different biocatalysts (e.g., natural oxidases and peroxidase mimics) together within confined frameworks. On the one hand, with the assistance of natural enzymes, INAzymes are capable of specifically recognizing targets. On the other hand, nanoscale confinement brought about by integration significantly enhances the cascade reaction efficiency. In this Feature Article, we highlight the newly developed INAzymes, covering from synthetic strategies to versatile applications in biodetection and therapeutics. Moreover, it is predicted that INAzymes with superior activities, specificity, and stability will enrich the research of nanozymes and pave new ways in designing multifunctional nanozymes.

Metal-Based Nanomaterials for Nanozymes

The use of metal nanomaterials for mimicking natural enzymes is discussed in this chapter. These nanozymes are roughly classified into two types: for type I, the nanozymes’ activities are entirely from the assembled monolayer onto a metallic core rather than the core itself; for type II, the nanozymes’ activities are originated from the metal nanomaterials themselves. For both of them, their enzyme mimetic activities (such as RNase mimics, DNase mimics, superoxide dismutase mimics, peroxidase mimics, catalase mimics, etc.) are discussed. The catalytic mechanisms for the multiple enzyme mimicking activities of metal nanomaterials are elucidated by combing computational studies with experimental results. Representative examples for applications, from biosensing and immunoassays to bioimaging and therapeutics, are covered.

Metal Oxide-Based Nanomaterials for Nanozymes

Metal oxide-based nanomaterials have been extensively studied to mimic various natural enzymes due to their unique properties. In this chapter, several metal oxide-based nanozymes are discussed. First, the use of cerium oxide nanomaterials for mimicking natural enzymes (such as superoxide dismutase, catalase, oxidase, peroxidase, phosphatase, etc.) is discussed. Second, the use of iron oxide nanomaterials for peroxidase mimics and other mimics is covered. Third, the enzyme mimicking activities of other metal oxides (such as vanadium oxide, cobalt oxide, copper oxide, etc.) are discussed. The catalytic mechanisms are also discussed if they have been elucidated. Selected examples for broad applications are discussed, which cover from glucose detection, DNA detection, immunoassay, and immunostaining, to neuroprotection, cardioprotection, cancer therapy, and tissue engineering.

Carbon-Based Nanomaterials for Nanozymes

Carbon-based nanomaterials, such as fullerene, graphene, carbon nanotubes, and their derivatives, have been extensively studied to mimic various natural enzymes owing to their fascinating catalytic activities. In this chapter, their enzyme mimetic activities (such as nuclease mimics, superoxide dismutase mimics, peroxidase mimics, etc.) are discussed. The catalytic mechanisms are also discussed if they have been elucidated. Representative examples for applications, from biosensing to therapeutics, are covered.

Multifunctional nanozymes: enzyme-like catalytic activity combined with magnetism and surface plasmon resonance

Over decades, as alternatives to natural enzymes, highly-stable and low-cost artificial enzymes have been widely explored for various applications. In the field of artificial enzymes, functional nanomaterials with enzyme-like characteristics, termed as nanozymes, are currently attracting immense attention. Significant progress has been made in nanozyme research due to the exquisite control and impressive development of nanomaterials. Since nanozymes are endowed with unique properties from nanomaterials, an interesting investigation is multifunctionality, which opens up new potential applications for biomedical sensing and sustainable chemistry due to the combination of two or more distinct functions of high-performance nanozymes. To highlight the progress, in this review, we discuss two representative types of multifunctional nanozymes, including iron oxide nanomaterials with magnetic properties and metal nanomaterials with surface plasmon resonance. The applications are also covered to show the great promise of such multifunctional nanozymes. Future challenges and prospects are discussed at the end of this review.

Other Nanomaterials for Nanozymes

The use of other nanomaterials beyond carbon-based nanomaterials, metal-based nanomaterials, and metal oxide-based nanomaterials for mimicking natural enzymes is discussed in this chapter. Prussian blue, metal-organic frameworks, metal chalcogenides, metal hydroxides, etc., have been selected as representative nanomaterials for mimicking peroxidase, superoxide dismutase, catalase, etc. The catalytic mechanisms are also discussed if they have been elucidated. Selected examples for in vitro biosensing, in vivo bioanalysis, and therapeutics are discussed to highlight the broad applications of these nanozymes.