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.

We summarize recent progress in the development of fluorogenic enzyme probes for a variety of diseases.

Nanopore-based techniques, which mimic the functions of natural ion channels, have attracted increasing attention as unique methods for single-molecule detection. The technology allows the real-time, selective, high-throughput analysis of nucleic acids through both biological and solid-state nanopores. In this Minireview, the background and latest progress in nanopore-based sequencing and detection of nucleic acids are summarized, and light is shed on a novel platform for nanopore-based detection.

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.

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.

New unsymmetrical diarylethenes were synthesized and their photochromic and fluorescent properties are tailored by Cu(2+) and CN(-) coordinations. A novel molecular logic keypad lock is constructed based on the fluorescence emission changes by the inputs of UV/visible irradiation, Cu(2+) and CN(-).

Stimuli-responsive polyacrylamide hydrogels crosslinked by glucosamine–boronate/G-quadruplexes or azobenzene-functionalized DNA reveal controlled stiffness using chemical or photochemical triggers.

Multi-triggered DNA/bipyridinium dithienylethene (DTE) hybrid carboxymethyl cellulose (CMC)-based hydrogels are introduced. DTE exhibits cyclic and reversible photoisomerization properties, switching between the closed state (DTE c ), the electron acceptor, and the open isomer (DTE o ) that lacks electron acceptor properties. One system introduces a dual stimuli-responsive hydrogel containing CMC chains modified with electron donor dopamine sites and self-complementary nucleic acids. In the presence of DTE c and the CMC scaffold, a stiff hydrogel is formed, cooperatively stabilized by dopamine/DTE c donor−acceptor interactions and by duplex nucleic acids. The cyclic and reversible formation and dissociation of the supramolecular donor−acceptor interactions, through light-induced photoisomerization of DTE, or via oxidation and subsequent reduction of the dopamine sites, leads to hydrogels of switchable stiffness. Another system introduces a stimuli-responsive hydrogel triggered by one of three alternative signals. The stiff, multi-triggered hydrogel consists of CMC chains cross-linked by dopamine/DTE c donor−acceptor interactions, and by supramolecular K + -stabilized G-quadruplexes. The G-quadruplexes are reversibly separated in the presence of 18-crown-6 ether and reformed upon the addition of K + . The stiff hydrogel undergoes reversible transitions between highstiffness and low-stiffness states triggered by light, redox agents, or K + /crown ether. The hybrid donor−acceptor/G-quadruplex cross-linked hydrogel shows shape-memory and self-healing features. By using three different triggers and two alternative memory-codes, e.g., the dopamine/DTE c or the K + -stabilized G-quadruplexes, the guided shape-memory function of the hydrogel matrices is demonstrated.