Simultaneous Disulfide and Boronic Acid Ester Exchange in Dynamic Combinatorial Libraries

Dynamic combinatorial chemistry has emerged as a promising tool for the discovery of complex receptors in supramolecular chemistry. At the heart of dynamic combinatorial chemistry are the reversible reactions that enable the exchange of building blocks between library members in dynamic combinatorial libraries (DCLs) ensuring thermodynamic control over the system. If more than one reversible reaction operates in a single dynamic combinatorial library, the complexity of the system increases dramatically, and so does its possible applications. One can imagine two reversible reactions that operate simultaneously or two reversible reactions that operate independently. Both these scenarios have advantages and disadvantages. In this contribution, we show how disulfide exchange and boronic ester transesterification can function simultaneous in dynamic combinatorial libraries under appropriate conditions. We describe the detailed studies necessary to establish suitable reaction conditions and highlight the analytical techniques appropriate to study this type of system.     

Biomedical applications of boronic acid polymers

Boron-containing organic compounds have found widespread use in synthetic organic chemistry. More recently, boronic acid-containing polymers have proven valuable in a variety of biomedical applications, including the treatment of HIV, obesity, diabetes, and cancer. However, as compared to many other classes of functional polymers, boronic acid-containing (co)polymers remain underutilized, despite their unique reactivity, solubility, and responsive nature. This Feature Article highlights research in this area, with particular focus on recent developments in synthesis, processing, and materials development that have enabled the preparation of new biomaterials. In addition to providing an overview to the current state of the art, we emphasize the versatility of boronic acid polymers and suggest routes for their further employment in other potential biomedical applications.     

Facile design of biomaterials by ‘click’ chemistry

The advent of the so‐called ‘click chemistry’ a decade ago has significantly improved the chemical toolbox for producing novel biomaterials. This review focuses primarily on the application of Cu(I)‐catalysed azide–alkyne 1,3‐cycloadditon in the preparation of numerous, diverse biomaterials and biomedical materials and concepts. In addition, the thiol–ene ‘click’ reaction is addressed in the same manner, and the possibility of using both click reactions orthogonally is highlighted. A strategy for the preparation of novel intriguing poly(ε‐caprolactone)‐based nanobiomaterials by orthogonal click chemistry is elaborated. The present state of creating functional and biologically active surfaces by click chemistry is presented. Finally, conducting surfaces based on an azide‐functionalized polymer with prospective biological sensor potential are introduced. Copyright © 2012 Society of Chemical Industry     

生物医用材料

概述了生物医用材料的类型及性质，提出了对生物医用材料的要求，化学和生物学的融合为找寻新型材料开辟了新途径。展望了医用材料的前景。     

生物材料制备新方法--超临界流体技术

虽然超临界流体技术的应用领域越来越广,但是在生物材料研究开发领域中的应用只是近几年的事。结合作者已开展的研究工作,阐述了超临界流体在生物材料加工、缓释控释药物制备、组织工程支架材料的成型以及异种骨移植前处理等方面的一些运用,对超临界流体技术在生物材料中的运用提出了一些新看法。     

Role of inorganic and theoretical chemistry in ceramics: past,present, and future

Abstract

Theoretical inorganic chemistry has evolved since Professor Mellor's time to include a new generation of quantum mechanics based calculational methods to understand and predict chemical reaction pathways. Semi-empirical molecular orbital (MO) calculations have been used in the fields of glass and silica structure analysis, fracture mechanics, sol–gel processing of net shape optics, porous matrixes for hybrid optics, sensors, and tissue engineering scaffolds. Applications of MO calculations in biomaterials interface reactions, biomimetics, and biomineralisation have also been made. Future directions for use of theoretical inorganic chemistry in the ceramic industry are forecast.     

Removable foams based on an epoxy resin incorporating reversible Diels–Alder adducts

We have successfully incorporated Diels–Alder reversible chemistry into epoxy resins. The Diels–Alder chemistry goes in the forward direction at 60 °C and reverses at or above 90 °C. One resin was formulated with other commercial ingredients into foamed epoxy. The foam, shown to have mechanical properties similar to foams formed with conventional epoxy resins, is being utilized for electronic encapsulation. Because of the built‐in reversible chemistry, the foams can be easily removed by dissolution in 1‐butanol at 90 °C. Removal allows for the rework, upgrading, or dismantlement of the electronic components. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1496–1502, 2002     

Biomaterials with Antibacterial and Osteoinductive Properties to Repair Infected Bone Defects

The repair of infected bone defects is still challenging in the fields of orthopedics, oral implantology and maxillofacial surgery. In these cases, the self-healing capacity of bone tissue can be significantly compromised by the large size of bone defects and the potential/active bacterial activity. Infected bone defects are conventionally treated by a systemic/local administration of antibiotics to control infection and a subsequent implantation of bone grafts, such as autografts and allografts. However, these treatment options are time-consuming and usually yield less optimal efficacy. To approach these problems, novel biomaterials with both antibacterial and osteoinductive properties have been developed. The antibacterial property can be conferred by antibiotics and other novel antibacterial biomaterials, such as silver nanoparticles. Bone morphogenetic proteins are used to functionalize the biomaterials with a potent osteoinductive property. By manipulating the carrying modes and release kinetics, these biomaterials are optimized to maximize their antibacterial and osteoinductive functions with minimized cytotoxicity. The findings, in the past decade, have shown a very promising application potential of the novel biomaterials with the dual functions in treating infected bone defects. In this review, we will summarize the current knowledge of novel biomaterials with both antibacterial and osteoinductive properties.     

Recent advances in shear-thinning and self-healing hydrogels for biomedical applications

Shear-thinning and self-healing hydrogels are being investigated in various biomedical applications including drug delivery, tissue engineering, and 3D bioprinting. Such hydrogels are formed through dynamic and reversible interactions between polymers or polypeptides that allow these shear-thinning and self-healing properties, including physical associations (e.g., hydrogen bonds, guest–host interactions, biorecognition motifs, hydrophobicity, electrostatics, and metal–ligand coordination) and dynamic covalent chemistry (e.g., Schiff base, oxime chemistry, disulfide bonds, and reversible Diels–Alder). Their shear-thinning properties allow for injectability, as the hydrogel exhibits viscous flow under shear, and their self-healing nature allows for stabilization when shear is removed. Hydrogels can be formulated as uniform polymer and polypeptide assemblies, as hydrogel nanocomposites, or in granular hydrogel form. This review focuses on recent advances in shear-thinning and self-healing hydrogels that are promising for biomedical applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48668.     

Synthesis and characterization of Ca–Sr–P coating on pure magnesium for biomedical application

There are growing evidences that Sr-containing calcium phosphate biomaterials can promote better osteo-precursor cell attachment and proliferation than pure calcium phosphate biomaterials. In this study, attempts were made to fabricate two kinds of Sr-substituted calcium phosphate (Ca–Sr–P) coatings on pure magnesium in electrolyte solutions with differing amounts of Sr(NO₃)₂ for biomedical application. The surface microstructure, composition and chemistry of the coatings were characterized by Scanning Electron Microscope (SEM), Energy-dispersive X-ray Spectroscopy (EDS), and X-ray Diffractometer (XRD), respectively. In addition, electrochemical and immersion tests were performed to evaluate the corrosion resistance of the Ca–Sr–P coated magnesium in phosphate buffered saline solution (PBS).     

Current advances concerning the most cited metal ions doped bioceramics and silicate-based bioactive glasses for bone tissue engineering

Studies related to biomaterials that stimulate the repair of living tissue have increased considerably, improving the quality of many people's lives that require surgery due to traumatic accidents, bone diseases, bone defects, and reconstructions. Among these biomaterials, bioceramics and bioactive glasses (BGs) have proved to be suitable for coating materials, cement, scaffolds, and nanoparticles, once they present good biocompatibility and degradability, able to generate osteoconduction on the surrounding tissue. However, the role of biomaterials in hard tissue engineering is not restricted to a structural replacement or for guiding tissue regeneration. Nowadays, it is expected that biomaterials develop a multifunctional role when implanted, orchestrating the process of tissue regeneration and providing to the body the capacity to heal itself. In this way, the incorporation of specific metal ions in bioceramics and BGs structure, including magnesium, silver, strontium, lithium, copper, iron, zinc, cobalt, and manganese are currently receiving enhanced interest as biomaterials for biomedical applications. When an ion is incorporated into the bioceramic structure, a new category of material is created, which has several unique properties that overcome the disadvantages of primitive material and favors its use in different biomedical applications. The doping can enhance handling properties, angiogenic and osteogenic performance, and antimicrobial activity. Therefore, this review aims to summarize the effect of selected metal ion dopants into bioceramics and silicate-based BGs in bone tissue engineering. Furthermore, new applications for doped bioceramics and BGs are highlighted, including cancer treatment and drug delivery.     

Containerless processing of Ca-Sr-Si system bioactive materials: Thermophysical properties and ion release behaviors

Silicate materials have shown excellent bioactivity to enhance bone regeneration by releasing bioactive ions to stimulate osteogenesis and angiogenesis. However, one of the remaining challenges is how to control the ion release from biomaterials in order to elucidate the relationship between the ion concentration and bioactivity. In this study, we report, for the first time, the synthesis of Ca-Sr-Si biomaterials by containerless processing (CP) technique and sol-gel (SG) method, and a systematic study on ion release behaviors of the materials. The phase and chemical compositions of the materials and the dissolution condition on ion release behaviors of the biomaterials were investigated. The results showed that CP was an effective method to prepare Ca-Sr-Si glass materials. The heat treatment promoted the phase transition of the glasses, and the ion release behaviors of the biomaterials can be tailored by controlling the chemical composition, phase composition, pH value and preparation methods.     

Wettability and osteoblastic cell adhesion on ultrapolished commercially pure titanium surfaces: the role of the oxidation and pollution states

The oxidation state of the surfaces of titanium-based biomaterials strongly depends on their previous history. This factor affects the titanium wettability and it probably conditions the success of the implanted biomaterials. However, the separate role of the pollution and oxidation states of metallic titanium surfaces remains still controversial. To elucidate this, it is required to standardize the initial surface state of titanium in terms of roughness and surface chemistry, and then, to monitor its wettability after the corresponding treatment. In this work, we studied finely polished surfaces of commercially pure titanium (cpTi) which were subjected to cleaning surface treatments. X-Photoelectron spectroscopy was used to characterize the surface chemistry and the oxide film thickness. The contact angle hysteresis in underwater conditions was measured with the growing/shrinking captive bubble method, which allowed for mimicking the real conditions of implantable devices. The water wettability of smooth cpTi surfaces was stabilized with weak thermal oxidation (230?°C, 30?min). The osteoblastic cell response of the stabilized and non-stabilized cpTi surfaces was analyzed. Although the oxidation and pollution states were also stabilized and normalized, no correlation was observed between the stable response in wettability of titanium and its cell adhesion.     

Fundamental and applied research on clay minerals: From climate and environment to nanotechnology

This brief overview comments on recent trends in scientific research and development of clay minerals and was stimulated by the compilation of papers for this special issue to pay tribute to the 34th International Geological Congress held in 2012. The essentially geological context of the conference was a reminder that increased understanding of the genesis and evolution of clays and clay minerals provides insights that have applications in mining, environmental management, paleoclimate, Earth and extraterrestrial sciences. The requirement for multidisciplinary knowledge, including geology, mineralogy, chemistry and materials science, and modern instrumentation and analysis of clay minerals, is essential to a full understanding of the genesis, role and potential new uses for these fine-grained industrial minerals. Latest studies are typically focused on processing and modifying of clay minerals as adsorbents, catalysts, and biomaterials. The emphasis for future work is on advanced clay-based nanomaterials for use in new approaches to sustainable energy, green environment, and human health.     

物理化学教学中有关电化学问题探讨

电化学是研究电现象与化学现象之间内在联系的一门科学。电化学无论在理论上还是在实际应用上都有十分丰富的内涵。电化学在物理化学教材中分为电解质溶液、可逆电池的电动势及其应用和电解与极化作用三章来介绍,是物理化学课程的重要组成部分。文章探讨了在物理化学教学中电极反应和极化曲线等与电化学有联系的几个问题,旨在对提高物理化学教学效果有帮助。     

Functionalization of magnetic nanoparticles for biomedical applications

Interest in utilizing magnetic nanoparticles for biomedical treatments originates from their external controllability of transportation and movement inside biological objects and magnetic heat generation. Advances in nanoparticle and nanotechnology enable us to produce magnetic nanoparticles of specific morphology and to engineer particle surfaces to manipulate their characteristics for specific applications. Intensive investigations and developments have been carried out in improving the quality of magnetic particles, regarding their size, shape, size distribution, their magnetism and their surface. The magnetic nanoparticles with appropriate surface chemistry can conjugate various biomaterials such as drugs, proteins, enzymes, antibodies, or nucleotides to be used for numerous in vivo applications including MRI contrast enhancement, immunoassay, hyperthermia, drug delivery, and cell separation. Here we review both the key technical principles of magnetic nanoparticle synthesis and the ongoing advancement of biomedical treatments using magnetic nanoparticles, specifically, the advancement in controlled drug delivery and hyperthermia.     

Dendritic Molecular Nanobatteries and the Contribution of Click Chemistry

This article is a mini-review mostly based on the work of the authors’ laboratory on the redox chemistry of metallodendrimers and gold nanoparticles, with emphasis on “click” chemistry. Late transition-metal sandwich complexes possess a rather unique ability to withstand two or three oxidation states without breakdown, especially with permethylated π-cyclopentadienyl or arene ligands. When they are linked to dendritic cores, the assembled nano-systems undergo chemically and electrochemically reversible transfer of a large number of electrons (up to 14,000). These multiple redox processes are useful for nanodevices behaving as nanobatteries for redox sensing, modified electrode surfaces and redox catalysis. Click chemistry was recently disclosed as one of the most powerful means to form such assemblies including both arene-cored and gold nanoparticle-cored dendrimers.     

A critical review on the cellular and molecular interactions at the interface of zirconia-based biomaterials

In the past few years, zirconia has gained a great attention among biomedical scientists due to its extraordinary strength and fracture toughness, negligible thermal conductivity, good biocompatibility and chemical inertness. In this regard, there is still room for the manipulation of zirconia-based biomaterials regarding the protein adsorption and subsequently cell responses to the surface. Protein adsorption on biomaterials surfaces start interpreting the construction and also arranging the surface characteristics into a biological language. In this review, the role of adsorbed proteins as key players in starting interactions between cells and zirconia-based biomaterials will be discussed in detail. The discussion will then highlight discussions on the implementation of innovative strategies to engineer the physiochemical properties of this class of biomaterials. It is expected that these promising solutions can better control proteins adsorption and cellular functions after implantation in the body.     

Toward living radical polymerization

Radical polymerization is one of the most widely used processes for the commercial production of high-molecular-weight polymers. The main factors responsible for the preeminent position of radical polymerization are the ability to polymerize a wide array of monomers, tolerance of unprotected functionality in monomer and solvent, and compatibility with a variety of reaction conditions. Radical polymerization is simple to implement and inexpensive in relation to competitive technologies. However, conventional radical polymerization severely limits the degree of control that researchers can assert over molecular-weight distribution, copolymer composition, and macromolecular architecture. This Account focuses on nitroxide-mediated polymerization (NMP) and polymerization with reversible addition-fragmentation chain transfer (RAFT), two of the more successful approaches for controlling radical polymerization. These processes illustrate two distinct mechanisms for conferring living characteristics on radical polymerization: reversible deactivation (in NMP) and reversible or degenerate chain transfer (in RAFT). We devised NMP in the early 1980s and have exploited this method extensively for the synthesis of styrenic and acrylic polymers. The technique has undergone significant evolution since that time. New nitroxides have led to faster polymerization rates at lower temperatures. However, NMP is only applicable to a restricted range of monomers. RAFT was also developed at CSIRO and has proven both more robust and more versatile. It is applicable to the majority of monomers subject to radical polymerization, but the success of the polymerization depends upon the selection of the RAFT agent for the monomers and reaction conditions. We and other groups have proposed guidelines for selection, and the polymerization of most monomers can be well-controlled to provide minimal retardation and a high fraction of living chains by using one of just two RAFT agents. For example, a tertiary cyanoalkyl trithiocarbonate is suited to (meth)acrylate, (meth)acrylamide, and styrenic monomers, while a cyanomethyl xanthate or dithiocarbamate works with vinyl monomers, such as vinyl acetate or N-vinylpyrrolidone. With the appropriate choice of reagents and polymerization conditions, these reactions possess most of the attributes of living polymerization. We have used these methods in the synthesis of well-defined homo-, gradient, diblock, triblock, and star polymers and more complex architectures, including microgels and polymer brushes. Applications of these polymers include novel surfactants, dispersants, coatings and adhesives, biomaterials, membranes, drug-delivery media, electroactive materials, and other nanomaterials.