Topics in Current Chemistry最新文献

8-Aminoquinoline is a common nitrogen-containing heterocyclic framework in many natural products, functional materials and useful drugs. It has been developed as a powerful bidentate directing group or ligand auxiliary in the field of C–H bond activation/functionalization in recent years. In this context, the synthesis of substituted 8-aminoquinoline is of great importance. In this review we focus on the functionalization of positions C2–C7 on the 8-aminoquinoline ring, which involves the formation of C–C and C–Z (Z?=?heteroatom) bonds by transition metal catalysts, photocatalysts or metal-free conditions. Mechanistically, a single electron transfer (SET) pathway is suggested in most cases.

DNA and protein are the most important two classes of biomacromolecules forming the basis of life. The conjugation of the two using crosslinking chemistries enables a combination of molecular recognition, enzymatic catalysis, and Watson–Crick hybridization properties. The DNA–protein conjugate with combined properties enables a broad range of applications, such as sensitive and selective bioassays, therapeutic agents, and building blocks for programmable nanoassemblies. In this review, we survey the conjugates from the aspects of conjugation chemistries as well as applications in biomedical and nanotechnology fields. We highlight the functions of both biological moieties of a conjugate for target binding and signal transduction in bioassays. We also review the use of DNA–protein conjugates for the construction of a variety of functional and dynamic nanostructures, from isolated hybrid cages to three-dimensional (3D) protein crystalline lattices. Moreover, these conjugates have been used as carriers to deliver enzymes or functional nucleic acids for disease treatments and gene editing.

Iron oxide nanoparticles (IONPs) have emerged as a promising alternative to conventional contrast agents (CAs) for magnetic resonance imaging (MRI). They have been extensively investigated as CAs due to their high biocompatibility and excellent magnetic properties. Furthermore, the ease of functionalization of their surfaces with different types of ligands (antibodies, peptides, sugars, etc.) opens up the possibility of carrying out molecular?MRI. Thus, IONPs functionalized with epithelial growth factor receptor antibodies, short peptides, like RGD, or aptamers, among others, have been proposed for the diagnosis of various types of cancer, including breast, stomach, colon, kidney, liver or brain cancer. In addition to cancer diagnosis, different types of IONPs have been developed for other applications, such as the detection of brain inflammation or the early diagnosis of thrombosis. This review addresses key aspects in the development of IONPs for MRI applications, namely, synthesis of the inorganic core, functionalization processes to make IONPs biocompatible and also to target them to specific tissues or cells, and finally in vivo studies in animal models, with special emphasis on tumor models.

Cellular functions rely on a series of organized and regulated multienzyme cascade reactions. The catalytic efficiencies of these cascades depend on the precise spatial organization of the constituent enzymes, which is optimized to facilitate substrate transport and regulate activities. Mimicry of this organization in a non-living, artificial system would be very useful in a broad range of applications—with impacts on both the scientific community and society at large. Self-assembled DNA nanostructures are promising applications to organize biomolecular components into prescribed, multidimensional patterns. In this review, we focus on recent progress in the field of DNA-scaffolded assembly and confinement of multienzyme reactions. DNA self-assembly is exploited to build spatially organized multienzyme cascades with control over their relative distance, substrate diffusion paths, compartmentalization and activity actuation. The combination of addressable DNA assembly and multienzyme cascades can deliver breakthroughs toward the engineering of novel synthetic and biomimetic reactors.

Self-assembly, which is ubiquitous in living systems, also stimulates countless synthetic molecular self-assembling systems. Most synthetic self-assemblies are realized by passive processes, going from high-energy states to thermodynamic equilibrium. Conversely, living systems work out of equilibrium, meaning they are energy-consuming, dissipative and active. In recently years, chemists have made extensive efforts to design artificial active self-assembly systems, which will be pivotal to emulating and understanding life. Among various strategies, emerging approaches based on DNA nanotechnology have attracted a lot of attention. Structural- as well as dynamic-DNA-nanotechnology offer diverse tools with which to design building blocks and to shape their assembly behaviors. To achieve active self-assembly, a synergy of diverse DNA techniques is essential, including structural design, controllable assembly–disassembly, autonomous assembly, molecular circuits, biochemical oscillators, and so on. In this review, we introduce progress towards, or related to, active assembly via DNA nanotechnology. Dynamic DNA assembly systems ranging from passive assembly–disassembly systems, to autonomous assembly systems to sophisticated artificial metabolism and time-clocking oscillation systems will be discussed. We catalogue these systems from the perspective of free energy change with the reaction process. We end the review with a brief outlook and discussion.

The efficacy of photocatalysis strongly depends on the activity of the catalysts and the operational factors, especially factors associated with mass transfer and the possibility of catalyst deactivation. The use of ultrasound has great potential to enhance catalyst activity, during both the synthesis and actual oxidation processes due to the cavitational effects of turbulence and liquid streaming. This article presents an overview of the application aspects of ultrasound, both in the synthesis of the photocatalyst and applications for wastewater treatment. A review of the literature revealed that the use of ultrasound in the synthesis processes can result in a catalyst with a lower mean size and higher surface area as well as uniform size distribution. The application of ultrasound in the actual photocatalytic oxidation facilitates enhancement of the oxidation capacity, leading to higher degradation rates, sometimes synergistic results and definitely?lower treatment times. This article also presents guidelines for the selection of the best operating conditions for the use of ultrasound in photocatalytic systems and includes a discussion on the possible reactor configurations suitable for large-scale operations. Overall, a combination of ultrasound with photocatalytic oxidation or the optimized application of ultrasound in catalyst synthesis can yield significant benefits.

DNA nanostructures hold great promise for various applications due to their remarkable properties, including programmable assembly, nanometric positional precision, and dynamic structural control. The past few decades have seen the development of various kinds of DNA nanostructures that can be employed as useful tools in fields such as chemistry, materials, biology, and medicine. Aptamers are short single-stranded nucleic acids that bind to specific targets with excellent selectivity and high affinity and play critical roles in molecular recognition. Recently, many attempts have been made to integrate aptamers with DNA nanostructures for a range of biological applications. This review starts with an introduction to the features of aptamer-functionalized DNA nanostructures. The discussion then focuses on recent progress (particularly during the last five?years) in the applications of these nanostructures in areas such as biosensing, bioimaging, cancer therapy, and biophysics. Finally, challenges involved in the practical application of aptamer-functionalized DNA nanostructures are discussed, and perspectives on future directions for research into and applications of aptamer-functionalized DNA nanostructures are provided.

DNA molecules with superior flexibility, affinity and programmability have garnered considerable attention for the controllable assembly of nanoparticles (NPs). By controlling the density, length and sequences of DNA on NPs, the configuration of NP assemblies can be rationally designed. The specific recognition of DNA enables changes to be made to the spatial structures of NP assemblies, resulting in differences in tailorable optical signals. Comprehensive information on the fabrication of DNA-driven NP assemblies would be beneficial for their application in biosensing and bioimaging. This review analyzes the progress of DNA-driven NP assemblies, and discusses the tunable configurations determined by the structural parameters of DNA skeletons. The collective optical properties, such as chirality, fluorescence and surface enhanced Raman resonance (SERS), etc., of DNA-driven NP assemblies are explored, and engineered tailorable optical properties of these spatial structures are achieved. We discuss the development of DNA-directed NP assemblies for the quantification of DNA, toxins, and heavy metal ions, and demonstrate their potential application in the biosensing and bioimaging of tumor markers, RNA, living metal ions and phototherapeutics. We hihghlight possible challenges in the development of DNA-driven NP assemblies, and further direct potential prospects in the practical applications of macroscopical materials and photonic devices.