Disulfide‐Bridged Organosilica Frameworks: Designed,Synthesis, Redox‐Triggered Biodegradation,and Nanobiomedical Applications

Over the past few years, silica‐based nanotheranostics have demonstrated their great potential for nano/biomedical applications. However, the uncontrollable and difficult degradability of their pure silica framework and long‐time in vivo retention still cause severe and unpredictable toxicity risks. Therefore, it is highly desirable to design and synthesize materials with safer framework structures and compositions. To this aim, the introduction of disulfide bonds into the silica framework can not only maintain high stability in physiological conditions, but also achieve a stimuli‐responsive biodegradation triggered by intracellular reducing microenvironment in living cells, especially in cancer cells. Once nanotheranostics with disulfide (i.e., thioether)‐bridged silsesquioxane framework are taken up by tumor cells via passive or active targeting, the disulfide bonds in the hybrid silica matrix can be cleaved by a high concentration of intracellular glutathione, enabling redox‐triggered biodegradation of the nanosystems for both concomitant release of the loaded therapeutic cargo and in vivo clearance. It is envisioned that such hybrid materials comprised of disulfide‐bridged silsesquioxane frameworks can become promising responsive and biodegradable nanotheranostics. This review summarizes the recent advances in the synthesis of hybrid organosilicas with disulfide‐bridged silsesquioxane frameworks, and discuss their redox‐triggered biodegradation behaviors combined with their biocompatibility and nanobiomedical applications.     

Iron Oxide‐Labeled Collagen Scaffolds for Non‐Invasive MR Imaging in Tissue Engineering

Non‐invasive imaging holds significant potential for implementation in tissue engineering. It can be used to monitor the localization and function of tissue‐engineered implants, as well as their resorption and remodelling. Thus far, however, the vast majority of effort in this area of research have focused on the use of ultrasmall super‐paramagnetic iron oxide (USPIO) nanoparticle‐labeled cells, colonizing the scaffolds, to indirectly image the implant material. Reasoning that directly labeling scaffold materials might be more beneficial (enabling imaging also in the case of non‐cellularized implants), more informative (enabling the non‐invasive visualization and quantification of scaffold degradation), and easier to translate into the clinic (cell‐free materials are less complex from a regulatory point‐of‐view), three different types of USPIO nanoparticles are prepared and incorporated both passively and actively (via chemical conjugation; during collagen crosslinking) into collagen‐based scaffold materials. The amount of USPIO incorporated into the scaffolds is optimized, and correlated with MR signal intensity, showing that the labeled scaffolds are highly biocompatible, and that scaffold degradation can be visualized using MRI. This provides an initial proof‐of‐principle for the in vivo visualization of the scaffolds. Consequently, USPIO‐labeled scaffold materials seem to be highly suitable for image‐guided tissue engineering applications.     

Natural Wax for Transient Electronics

Emerging classes of bioresorbable electronic materials serve as the basis for active biomedical implants that are capable of providing sensing, monitoring, stimulating, and other forms of function over an operating period matched to biological processes such as wound healing. These platforms are of interest because subsequent dissolution, enzymatic degradation, and/or bioresorption can eliminate the need for surgical extraction. This report introduces natural wax materials as long‐lived, hydrophobic encapsulation layers for such systems, where biodegradation eventually occurs by chain scission. Studies of wax stability as an encapsulation material demonstrate the ability to retain operation of underlying biodegradable electronic systems for durations between a few days to a few weeks during complete immersion in aqueous solutions in ex‐vivo physiological conditions. Electrically conductive composites result from the addition of tungsten micro/nanoparticles, as a conductive, printable paste with similar lifetimes. Demonstrations of these materials in partially biodegradable wireless light‐emitting diodes and near‐field communication circuits illustrate their use in functional bioresorbable electronic systems. Investigations in animal models reveal no signs of toxicity or other adverse biological responses.     

Chemical degradation mechanisms of highly efficient blue phosphorescent emitters used for organic light emitting diodes

The stability and the degradation processes of two highly efficient blue-emitting phosphorescent materials, iridium(III) bis(4′,6′-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6) and bis(2-(4,6-difluorophenyl) pyridyl-N,C2′)iridium(III)picolinate (FIrpic), which are commonly used as emitters in organic light emitting diodes (OLEDs), are investigated. Using single layers devices, the optical response and the half-lifetime behavior of the materials are investigated. Layers of FIr6 exposed to UV-light show the formation of a red emitting degradation product. We analyze the chemical reactions of the materials using laser desorption/ionization time-of-flight mass spectrometry. Several products related to the chemical dissociation of the FIr6 molecule as well as charge complex formation between the emitter and the emitter dissociation products are detected. FIr6 and FIrpic are also compared by lifetime studies on commonly used OLED structures. We show that single layers and OLEDs based on FIrpic exhibit higher stability than those based on FIr6. An explanation for this behavior can be found by considering the chemical structure of the molecules.     

Multiphoton Lithography as a Promising Tool for Biomedical Applications

Multiphoton lithography (MPL) is a powerful and useful structuring tool capable of generating 2D and 3D arbitrary micro- and nanometer features of various materials with high spatial resolution down to nm-scale. This technology has received tremendous interest in tissue engineering and medical device manufacturing, due to its ability to print sophisticated structures, which is difficult to achieve through traditional printing methods. Thorough consideration of two-photon photoinitiators (PIs) and photoreactive biomaterials is key to the fabrication of such complex 3D micro- and nanostructures. In the current review, different types of two-photon PIs are discussed for their use in biomedical applications. Next, an overview of biomaterials (both natural and synthetic polymers) along with their crosslinking mechanisms is provided. Finally, biomedical applications exploiting MPL are presented, including photocleaving and photopatterning strategies, biomedical devices, tissue engineering, organoids, organ-on-chip, and photodynamic therapy. This review offers a helicopter view on the use of MPL technology in the biomedical field and defines the necessary considerations toward selection or design of PIs and photoreactive biomaterials to serve a multitude of biomedical applications.     

Biocatalytic Metal‐Organic Framework‐Based Artificial Cells

Artificial cells or cell mimics have drawn significant attention in cell biology and material science in the last decade and its development will provide a powerful toolbox for studying the origin of life and pave the way for novel biomedical applications. Artificial cells and their subcompartments are typically constructed from a semipermeable membrane composed of liposomes, polymersomes, hydrogels, or simply aqueous droplets enclosing bioactive molecules to perform cellular‐mimicking activities such as compartmentalization, communication, metabolism, or reproduction. Despite the rapid progress, concerns regarding their physical stability (e.g., thermal or mechanical) and tunability in membrane permeability have significantly hindered artificial cells systems in real‐life applications. In addition, developing a facile and versatile system that can mimic multiple cellular tasks is advantageous. Here, an ultrastable, multifunctional and stimulus‐responsive artificial cell system is reported. Constructed from metal‐phenolic network membranes enclosing enzyme‐containing metal‐organic frameworks as organelles, the bionic cell system can mimic multiple cellular tasks including molecular transport regulation, cell metabolism, communication and programmed degradation, and significantly extends its stability range across various chemical and physical conditions. It is believed that the development of such responsive cell mimics will have significant potentials for studying cellular reactions and have future applications in biosensing and drug delivery.     

Intelligent Sonocatalytic Nanoagents for Energy Conversion-Based Therapies

Sonodynamic therapy (SDT) utilizes ultrasound-irradiating sonosensitizers to convert ultrasonic vibrations into chemical energy and produce reactive oxygen species (ROS) that cause cell apoptosis or necrosis. SDT demonstrates significant potential in the treatment of deep tumors without normal tissue damage. Rapid advances in the efficacy of SDT have enabled the rational design and construction of novel intelligent sonocatalytic nanoagents (SCNs) with various functions for versatile biomedical applications. Herein, the most recent critical advancements in intelligent SCNs for energy conversion-based therapies are discussed. Typical SCNs including organic molecules, organic micro-/nanoparticles, inorganic micro-/nanoparticles, organic/inorganic hybrids, and piezoelectric materials are introduced and summarized in detail. Furthermore, these intelligent SCNs are designed for different energy conversion-based therapies such as SDT, SDT-assisted chemotherapy, SDT-assisted photodynamic therapy, SDT-assisted photothermal therapy, SDT-assisted gas therapy, SDT-assisted sonoporation from the cell membrane to the blood brain barrier, and high-intensity focused ultrasound-based sonothermal therapy. It is believed that this review will provide an overview of the application of intelligent SCNs in sonodynamic therapies to better understand the limitations and challenges of these SCNs and further promote their advancements for a broad range of biomedical applications.     

Tailoring Hyaluronic Acid Hydrogels for Biomedical Applications

Hyaluronic acid (HA) is an attractive anionic polysaccharide polymer with inherent pharmacological properties and versatile chemical groups for modification. Due to their water retention ability, biocompatibility, biodegradation, cluster of differentiation-44 targeting, and highly designable capacity, HA hydrogels have been an emerging biomaterial, showing tailoring performance in terms of chemical modifications and hydrogel forms. Various preparation technologies have been developed for the fabrication of the tailoring HA hydrogels with unique structures and functions. They have been utilized in diverse biomedical applications like drug delivery and tissue engineering scaffolds. Herein, this review comprehensively summarizes the HA derivatives with different molecule weights and functional modifications. Then the various fabrication methods to obtain tailoring hydrogels in the forms of nanogel, nanofiber, microparticle, microneedle patch, injectable hydrogel, and scaffold are reviewed as well. The emphasis is focused on the shining biomedical applications of these tailoring HA hydrogels in anti-bacteria, anti-inflammation, wound healing, cancer treatment, regenerative medicine, psoriasis treatment, diagnosis, etc. The potentials and prospects are subsequently given to inspire further investigation, aiming at accelerating product translation from research to clinic.     

Enzyme Mimics for Engineered Biomimetic Cascade Nanoreactors: Mechanism,Applications, and Prospects

Multiple enzyme-driven biological catalytic cascades occur in living organisms, guiding highly efficient and selective transformations of substrates. Inspired by the merits of these biological catalytic cascade systems, enormous efforts have been devoted to developing novel cascade catalytic systems to mimic biological cascade catalytic reactions over the past few years. Nanozymes, a class of enzyme mimics, are nanomaterials with enzyme-like catalytic activity. The emergence and development of nanozymes has significantly advanced the development of biomimetic cascade nanoreactors. Currently, biomimetic cascade nanoreactors driven by advanced nanozymes have been widely used and exhibit many advantages such as superior cascade catalytic efficiency and high stability, resulting in significant advancements in biosensing and biomedical applications. The latest advances in understanding the cascade catalytic mechanism of nanozyme-engineered biomimetic cascade catalytic nanoreactors and their progressive applications for biosensing and biomedical applications are comprehensively covered here. First, nanozyme and enzyme/nanozyme-engineered biomimetic cascade catalytic nanoreactors are categorized according to their catalytic mechanism and properties. Then, the biosensing and biomedical applications, including cancer therapy, antibacterial activity, antioxidation, and hyperuricemia therapy of the cascade catalytic systems are covered. The conclusion describes the most important challenges and opportunities remaining in this exciting area of research.     

Emerging Chemistry in Enhancing the Chemical and Photochemical Stabilities of Fused-Ring Electron Acceptors in Organic Solar Cells

The power conversion efficiency of organic solar cells (OSCs) has made exceptionally rapid progress in the past five years owing to the emergence of fused-ring electron acceptors (FREAs). To achieve the commercialization, it is urgent to resolve the stability issues of OCSs from materials to devices. In particular, the state-of-the-art FREAs, often synthesized by Knoevenagel condensation, generally contain two exocyclic vinyl groups (CC bond) as the conjugated bridges, which inevitably exhibit an obvious electron-deficient characteristic due to the strong push-pull electronic effect. As a result, these vinyl bridges are vulnerable to nucleophile attacking and/or photooxidation, leading to poor chemical and photochemical stabilities of FREAs that easily cause the degradation of device performance. In this perspective, an in-depth understanding of the degradation mechanism of FREAs is provided, and then effective strategies reported recently are reviewed for improving the chemical and photochemical stabilities of FREAs from interfacial engineering to molecular engineering to additive engineering. Finally, a conclusion and outlook for the future design of highly efficient and stable FREAs are also presented.     

Multifunctional Silver‐Exchanged Zeolite Micromotors for Catalytic Detoxification of Chemical and Biological Threats

Multifunctional reactive‐zeolite‐based micromotors have been developed and characterized toward effective and rapid elimination of chemical and biological threats. The incorporation of silver ions (Ag⁺) into aluminosilicate zeolite framework imparts several attractive functions, including strong binding to chemical warfare agents (CWA) followed by effective degradation, and enhanced antibacterial activity. The new zeolite‐micromotors protocol thus combines the remarkable adsorption capacity of zeolites and the efficient catalytic properties of the reactive Ag⁺ ions with the autonomous movement of the zeolite micromotors for an accelerated detoxification of CWA. Furthermore, the high antibacterial activity of Ag⁺ along with the rapid micromotor movement enhances the contact between bacteria and reactive Ag⁺, leading to a powerful “on‐the‐fly” bacteria killing capacity. These attractive adsorptive/catalytic features of the self‐propelled zeolite micromotors eliminate secondary environmental contamination compared to adsorptive micromotors. The distinct cubic geometry of the zeolite micromotors leads to enhanced bubble generation and faster movement, in unique movement trajectories, which increases the fluid convection and highly efficient detoxification of CWA and killing of bacteria. The attractive capabilities of these zeolite micromotors will pave the way for their diverse applications in defense, environmental and biomedical applications in more economical and sustainable manner.     

Energy Transfer to a Stable Donor Suppresses Degradation in Organic Solar Cells

Despite many advances toward improving the stability of organic photovoltaic devices, environmental degradation under ambient conditions remains a challenging obstacle for future application. Particularly conventional systems employing fullerene derivatives are prone to oxidize under illumination, limiting their applicability. Here, the environmental stability of the small molecule donor DRCN5T together with the fullerene acceptor PC₇₀BM is reported. It is found that this system exhibits exceptional device stability, mainly due to almost constant short‐circuit current. By employing ultrafast femtosecond transient absorption spectroscopy, this remarkable stability is attributed to two separate mechanisms: 1) DRCN5T exhibits high intrinsic resistance toward external factors, showing no signs of deterioration. 2) The highly sensitive PC₇₀BM is stabilized against degradation by the presence of DRCN5T through ultrafast, long‐range energy transfer to the donor, rapidly quenching the fullerene excited states which are otherwise precursors for chemical oxidation. It is proposed that this photoprotective mechanism be utilized to improve the device stability of other systems, including nonfullerene acceptors and ternary blends.     

Fullerene Polymer Complex Inducing Dipole Electric Field for Stable Perovskite Solar Cells

Lead halide perovskite solar cells (PSCs) have demonstrated great potential for realizing low‐cost and easily fabricated photovoltaics. At this juncture, power conversion efficiency and long‐term stability are two important factors limiting their transition. PSCs exhibit rapid environmental degradation since the perovskite layer is very sensitive to factors such as humidity, temperature, and ultraviolet light. Here, a novel successful approach is demonstrated that simultaneously improves the efficiency and stability of PSCs. This approach relies on incorporation of a dual‐functional polymethyl methacrylate (PMMA)–fullerene complex into the perovskite layer. The fullerene within perovskite layer forms a localized dipole‐like electric field that favors electron–hole separation, resulting in significant improvement in current density and fill factor with conversion efficiency reaching 18.4%. The molecular‐scale coating of hydrophobic PMMA on the perovskite grain boundary effectively blocks moisture penetration into the perovskite, thereby, significantly improving the stability against moisture, heat, and light. The PSCs with PMMA–fullerene complex showed no photovoltaic performance degradation for 250 d and exhibited 60 times higher stability compared to the state‐of‐the‐art devices under continuous 1 sun illumination in ambient air.     

碳纳米管介电电泳组装及过程控制研究进展

碳纳米管具有独特的结构和卓越的电学、热学、力学等性能,有望在微纳电子、微纳机电系统、传感器、新能源、光学等诸多领域获得具有深远影响的应用。碳纳米管的组装是其获得广泛应用的重要前提,基于介电电泳的组装和过程控制技术近年来得到了迅速发展。这些技术包括回路中串联自限制性电阻,间隙电信号实时监测和反馈控制,三维结构的组装和包覆,引入不同形状浮动电极等。对碳纳米管介电电泳组装及各种新技术做了系统介绍,并对各种方法的优缺点进行了对比与总结,为探索稳定、高效的碳纳米管自动组装方法提供帮助。     

A Highly Elastic and Rapidly Crosslinkable Elastin‐Like Polypeptide‐Based Hydrogel for Biomedical Applications

Elastin‐like polypeptides (ELPs) are promising for biomedical applications due to their unique thermoresponsive and elastic properties. ELP‐based hydrogels have been produced through chemical and enzymatic crosslinking or photocrosslinking of modified ELPs. Herein, a photocrosslinked ELP gel using only canonical amino acids is presented. The inclusion of thiols from a pair of cysteine residues in the ELP sequence allows disulfide bond formation upon exposure to UV light, leading to the formation of a highly elastic hydrogel. The physical properties of the resulting hydrogel such as mechanical properties and swelling behavior can be easily tuned by controlling ELP concentrations. The biocompatibility of the engineered ELP hydrogels is shown in vitro as well as corroborated in vivo with subcutaneous implantation of hydrogels in rats. ELP constructs demonstrate long‐term structural stability in vivo, and early and progressive host integration with no immune response, suggesting their potential for supporting wound repair. Ultimately, functionalized ELPs demonstrate the ability to function as an in vivo hemostatic material over bleeding wounds.     

微操作机器人系统上位机软件的设计

由生物医学与微操作机器人结合产生的生物微操作机器人已成为工程技术领域的关键技术。本文基于MFC开发平台,采用RS-232通讯方式设计了一款微操作机器人系统的上位机软件,提供友好的图形化界面,方便了实验人员控制操作工具对细胞进行操作。测试结果表明,软件运行良好,可较好地应用于生物微操作机器人系统。     

Degradation Mechanism of Perovskite Light‐Emitting Diodes: An In Situ Investigation via Electroabsorption Spectroscopy and Device Modelling

The past few years have seen a significant improvement in the efficiency of organometal halide‐perovskite‐based light‐emitting diodes (PeLEDs). However, poor operation stability of the devices still hinders the commercialization of this technology for practical applications. Despite extensive studies on the degradation mechanisms of perovskite thin films, it remains unclear where and how degradation occurs in a PeLED. Electroabsorption (EA) spectroscopy is applied to study the degradation process of PeLEDs during operation and directly evaluates the stability of each functional layer (i.e., charge transporting layers and light‐emitting layer) by monitoring their unique optical signatures. The EA measurements unambiguously reveal that the degradation of the PeLEDs occurs predominantly in the perovskite layer. With finite‐element method‐based device modeling, it is further revealed that the degradation may initiate from the interface between the perovskite and hole transporting layers and that vacancy, antisite, or interstitial defects can further accelerate this degradation. Inspired by these observations, a surface‐treatment step is introduced to passivate the perovskite surface with phenethylammonium iodide. The passivation leads to a drastic enhancement of the PeLED stability, with the operation lifetime increased from 1.5 to 11.3 h under a current density of 100 mA cm^?2.     

A Review of MOFs and Their Composites-Based Photocatalysts: Synthesis and Applications

Photocatalysis is considered to be a green and environment-friendly technology since it can convert solar energy into other types of chemical energies. Over the past several years, metal-organic frameworks (MOFs)-based photocatalysts have received remarkable research interest due to their unique morphology, high photocatalytic performance, good chemical stability, easy synthesis, and low cost. In this review, the synthetic strategies of developing MOFs-based photocatalysts are first introduced. Second, the recent progress in the fabrication of various types of MOFs composites photocatalysts is summarized. Third, the different applications including hydrogen evolution reaction, oxygen evolution reaction, overall water splitting, nitrogen reduction reaction, carbon dioxide reduction reaction as well as photodegradation of organic pollutants of MOFs-based photocatalysts are summed up. Finally, the challenges and some suggestions for the future development of MOFs- and their composites-based photocatalysts are also highlighted. It is expected that this report will help researchers to systematically devise and develop highly efficient photocatalysts based on MOFs and their composites.     

Study of Physically Transient Insulating Materials as a Potential Platform for Transient Electronics and Bioelectronics

Controlled degradation and transiency of materials is of significant importance in the design and fabrication of degradable and transient biomedical and electronic devices and platforms. Here, the synthesis of programmable biodegradable and transient insulating polymer films is reported, which have sufficient physical and chemical properties to be used as substrates for the construction of transient electronics. The composite structure can be used as a means to control the dissolution and transiency rate of the polymer composite film. Experimental and computational studies demonstrate that the addition of gelatin or sucrose to a PVA polymer matrix can be used as a means to program and either slow or enhance the transiency of the composite. The dissolution of the polymer composites are fitted with inverse exponential functions of different time constants; the lower time constants are an indication of faster transiency of the polymer composite. The addition of gelatin results in larger time constants, whereas the addition of sucrose generally results in smaller time constants.     

Highly Efficient and Water‐Insensitive Self‐Healing Elastomer for Wet and Underwater Electronics

Integrating self‐healing capabilities into soft electronic devices increases their durability and long‐term reliability. Although some advances have been made, the use of self‐healing electronics in wet and/or (under)water environments has proven to be quite challenging, and has not yet been fully realized. Herein, a new highly water insensitive self‐healing elastomer with high stretchability and mechanical strength that can reach 1100% and ≈6.5 MPa, respectively, is reported. The elastomer exhibits a high (>80%) self‐healing efficiency (after ≈ 24 h) in high humidity and/or different (under)water conditions without the assistance of an external physical and/or chemical triggers. Soft electronic devices made from this elastomer are shown to be highly robust and able to recover their electrical properties after damages in both ambient and aqueous conditions. Moreover, once operated in extreme wet or underwater conditions (e.g., salty sea water), the self‐healing capability leads to the elimination of significant electrical leakage that would be caused by structural damages. This highly efficient self‐healing elastomer can help extend the use of soft electronics outside of the laboratory and allow a wide variety of wet and submarine applications.