Photochromism is a term that describes the photoreversible isomerization between two different states or isomers with distinct performances. Among all the photochromic molecule family, diarylethene ...is considered one of the most popular star molecules on account of its fast photoresponsibility, excellent thermal stability, fatigue resistance, high photoreaction quantum yield, and conversion ratio as well as good performances in both solution and solid phases. In the past decades, the development of diarylethene is witnessed in molecule design, solution applications, surface/interface assembly, bulky crystals and polymers, optic‐electronic devices fabrication, and biotechnology. This review mainly focuses on the latest development of diarylethenes in recent five years and commences with the newly designed molecular structures with functional ethene bridges and aryl moieties. The application of diarylethenes in materials science, soft materials, molecular data processing, and biomaterials, is further discussed in prospect. A brief summary is given in the end of the review together with some perspectives.
The development of photochromic diarylethene materials in the past five years is reviewed in this article. This review first focuses on the newly designed diarylethene structures with functional ethene bridges, aryl groups, and visible light photochromism. Then, applications of diarylethene derivatives in broad research areas of materials science are introduced, including soft materials, data processing systems, as well as biomaterials.
Photochromic materials are a family of compounds which can undergo reversible photo‐switches between two different states or isomers with remarkably different properties. Inspired by their smart ...photo‐switchable characteristics, a variety of light‐driven functional materials have been exploited, such as ultrahigh‐density optical data storage, molecular switches, logic gates, molecular wires, optic/electronic devices, sensors, bio‐imaging and so on. This review commences with a brief description of exciting progress in this field, from systems in solution to modified functional surfaces. Further development of these photo‐switchable systems into practical applications as well as existing challenges are also discussed and put in prospect.
Inspired by the smart photoswitchable characteristics of photochromic materials, a variety of light‐driven functional materials have been exploited, such as ultrahigh‐density optical data storage, molecular switches, logic gates, molecular wires, optic/electronic devices, sensors, bio‐imaging and so on. This review commences with a brief description of exciting progress in this field and further development of these photo‐switchable systems into practical applications as well as existing challenges are also discussed.
Traditional biochemical methods for enzyme detection are mainly based on antibody-based immunoassays, which lack the ability to monitor the spatiotemporal distribution and, in particular, the in situ ...activity of enzymes in live cells and in vivo. In this review, we comprehensively summarize recent progress that has been made in the development of small-molecule as well as material-based fluorogenic probes for sensitive detection of the activities of enzymes that are related to a number of human diseases. The principles utilized to design these probes as well as their applications are reviewed. Specific attention is given to fluorogenic probes that have been developed for analysis of the activities of enzymes including oxidases and reductases, those that act on biomacromolecules including DNAs, proteins/peptides/amino acids, carbohydrates and lipids, and those that are responsible for translational modifications. We envision that this review will serve as an ideal reference for practitioners as well as beginners in relevant research fields.
Current development of light-responsive materials and technologies imposes an urgent demand on visible-light photoswitching on account of its mild excitation with high penetration ability and low ...photo-toxicity. However, complicated molecular design and laborious synthesis are often required for visible-light photoswitch, especially for diarylethenes. Worse still, a dilemma is encountered as the visible-light excitation of the diarylethene is often achieved at the expense of photochromic performances. To tackle these setbacks, we introduce a building-block design strategy to achieve all-visible-light photochromism with the triplet-sensitization mechanism. The simply designed diarylethene system is constructed by employing a sensitizer building-block with narrow singlet-triplet energy gap (ΔE
) to a diarylethene building-block. A significant improvement on the photochromic efficiency is obtained as well as an enhanced photo-fatigue resistance over those under UV irradiation. The balance between the visible-light excitation and decent photochromism is thus realized, promoting a guiding principle for the visible-light photochromism.
Due to their similarity to some bio‐architectures, for example, extracellular matrix, hydrogels are considered as bio‐inspired networks with bio‐mimetic and bio‐functional properties. With natural ...cytocompatibility and biocompatibility, hydrogels nowadays are more and more involved in various bio‐applications including shape morphing, artificial muscles, soft robotics, regenerative medicine, and so on. As an important subclass, stimuli‐responsive hydrogels have been attracting interest within decades. In response to single or multi‐triggers in biological microenvironment, stimuli‐responsive hydrogels can undergo phase transition, stiffness change, or biochemical properties activation, which make them intriguing biomaterials with broad applications including sensing, drug delivery, tissue engineering, and wound healing. This review presents typical synthetic and natural gelators comprising small molecules and polymers as building blocks of functional architectures. The fabrication strategies of hydrogels varied from supramolecular assembly to dynamic covalent binding are detailed. Various exogenous or endogenous, physical or chemical, and synthetic or natural stimuli together with response mechanism, design principle are demonstrated. Through recent examples from different perspectives, such as bionic devices, wound dressing, and cargo carrier, the benefits and opportunities of stimuli‐responsive hydrogels for biological applications are highlighted. Finally, the current challenges and future prospects in view of translation from fundamental researches to clinical application are briefly discussed.
In this review, the authors aim to provide guidelines for researchers to design stimuli‐responsive hydrogels of their own interest. Different kinds of construction mode including supramolecular assembly, radical polymerization, chemical reaction and so on are introduced. Different hydrogels response to contact and non‐contact, synthetic and natural, and endogenous and exogenous signal are discussed. Various applications developed and will be developed in the future are evaluated, especially in the field of tissue engineering and regeneration medicine, which are still at its primary stage and in an urgent need of development. The growing of stimuli‐responsive hydrogels is expected to contribute to this field and provide promising perspectives.
Development of powerful fluorescence imaging probes and techniques sets the basis for the spatiotemporal tracking of cells at different physiological and pathological stages. While current imaging ...approaches rely on passive probe-analyte interactions, here we develop photochromic fluorescent glycoprobes capable of remote light-controlled intracellular target recognition. Conjugation between a fluorophore and spiropyran produces the photochromic probe, which is subsequently equipped with a glycoligand "antenna" to actively localize a target cell expressing a selective receptor. We demonstrate that the amphiphilic glycoprobes that form micelles in water can selectively enter the target cell to operate photochromic cycling as controlled by alternate UV/Vis irradiations. We further show that remote light conversion of the photochromic probe from one isomeric state to the other activates its reactivity toward a target intracellular analyte, producing locked fluorescence that is no longer photoisomerizable. We envision that this research may spur the use of photochromism for the development of bioimaging probes.Fluorescence sensing in biological environments is prone to background signal interference. Here the authors design a photochromic fluorescent glycoprobe for light-controlled photo-switchable cell imaging and photo-activated target recognition, resulting in an increased sensing precision.
A new class of stimuli-responsive DNA-based polyacrylamide hydrogels is described. They consist of glucosamine-boronate ester-crosslinked polyacrylamide chains being cooperatively bridged by ...stimuli-responsive nucleic acids. The triggered closure and dissociation of the stimuli-responsive units lead to switchable stiffness properties of the hydrogel. One hydrogel includes glucosamine-boronate esters and K
-ion-stabilized G-quadruplex units as cooperative crosslinkers. The hydrogel bridged by the two motifs reveals high stiffness, whereas the separation of the G-quadruplex bridges by 18-crown-6-ether yields a low stiffness hydrogel. By cyclic treatment of the hydrogel with K
-ions and 18-crown-6-ether, it is reversibly cycled between high and low stiffness states. The second system involves a photo-responsive hydrogel that reveals light-induced switchable stiffness functions. The polyacrylamide chains are cooperatively crosslinked by glucosamine-boronate esters and duplex nucleic acid bridges stabilized by
-azobenzene intercalator units. The resulting hydrogel reveals high stiffness. Photoisomerization of the
-azobenzene units to the
-azobenzene states results in the separation of the duplex nucleic acid bridges and the formation of a low stiffness hydrogel. The control over the stiffness properties of the hydrogel matrices by means of K
-ions/crown ether or photoisomerizable
-azobenzene/
-azobenzene units is used to develop shape-memory, self-healing, and controlled drug-release hydrogel materials.
DNA origami tiles provide nanostructures for the spatial and temporal control of functional loads on the scaffolds. Here we introduce the active generation of nanoholes in the origami scaffolds using ...DNAzymes or light as triggers and present the programmed and switchable catalysis in the resulting nanocavities. We engineer "window" domains locked into the origami scaffolds by substrates of the Zn
-ion- or Pb
-ion-dependent DNAzymes. Using Zn
ions and/or Pb
ions, the programmed unlocking of the "window" domains is demonstrated. The tailored functionalization of the origami scaffolds allows the programmed operation of catalytic processes in the confined nanocavities. Also, the "window" domain is integrated into the origami scaffold using photoisomerizable azobenzene-modified locks. The cyclic photoisomerization of the locks between the cis and trans states leads to a reversible opening and closure of the nanoholes and to the cyclic light-induced switching of catalytic processes in the nanocavities.
Single‐cell and in situ cell‐based operation with nanopipette approach offers a possibility to elucidate the intracellular processes and may aid the improvement of therapy efficiency and precision. ...We present here a photo‐responsive hydrogel‐nanopipette hybrid system that can achieve single‐cell operation with high spatial/temporal resolution and negligible cell damage. This strategy overcomes long‐time obstacles in nanopipette single‐cell studies as high electric potential (ca. 1000 mV) or organic solvent is always used during operations, which would inevitably impose disturbance and damage to targeted cells. The light‐triggered system promotes a potential‐free, non‐invasive single‐cell injection, resulting in a well‐retained cell viability (90 % survival rate). Moreover, the photo‐driven injection enables a precisely dose‐controllable single‐cell drug delivery. Significantly reduced lethal doses of doxorubicin (163–217 fg cell−1) are demonstrated in corresponding cell lines.
The fabrication of photo‐responsive hydrogel‐nanopipette system ensures both precision single‐cell operation and high cell preservation. Upon light‐controlled, non‐invasive operation, a high cell viability over 90 % as well as precise quantification of injection are obtained. Hence, a single‐cell precise‐dosing is achieved with a minimum lethal dose of 163–217 fg cell−1.
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