Cellular uptake plays an important role in efficient drug delivery, and conventional approaches are capable of regulation of cellular uptake but do not provide spatiotemporal precision. In this study, visible light-responsive photoacid-based nanogels (PA nGels) are developed with the aim of achieving dynamic control over cellular uptake. The physicochemical properties (particle size, zeta potential, stiffness, and reversibility) of these nanogels under visible light irradiation are systematically investigated. This study investigates the intracellular uptake efficiency of PA nGels by human gingival fibroblasts, a key cell type in periodontal tissues, to elucidate the relationships among their structure, properties, and functions. It has been demonstrated that under light irradiation, nanogels containing PA moieties exhibited conformational transitions in size and zeta potential. These alterations are ascribed to the equilibrium between volume, surface charge and hydrophilicity. The results of cellular uptake experiments demonstrate that the uptake is influenced when the PA nGels are irradiated, increasing the intracellular uptake. This study proposes a rational strategy for enhancing cellular uptake efficiency, with the potential to improve drug delivery to target cells.

Spiropyrans are a central class of molecular photoswitches whose reversible light‐induced isomerization between a closed, colourless spiro form and an open, coloured merocyanine form allows for their broad applicability in sensing, smart materials, and molecular machines. This review provides a structured framework for understanding how targeted chemical modifications can be used to control and fine‐tune the photochromic behaviour of these smart molecules. We first trace the historical evolution of spiropyrans, highlighting the development of nitrospiropyran as the prototypical photochrome and the branching of related families such as spirothiopyrans, spirooxazines, photoacids, and styryl cyanines. Particular emphasis is placed on how substituents, molecular strain, and heteroatom incorporation influence key properties such as absorption, thermodynamic stability, and switching efficiency. In addition to structural variations, we discuss how the use of acids to modulate photoisomerization led to the emergence of metastable‐state photoacids, providing unprecedented and reversible control over pH in aqueous environments. By systematically mapping structure–property relationships, this review highlights the delicate interplay between chemical design and environmental responsiveness in spiropyran systems. Overall, this review aims to serve as a comprehensive and practical guide for researchers seeking to design and apply spiropyran‐based photoswitches, thereby expanding their potential in photonic, chemical, and biological applications.

We demonstrate here that light can be used to modulate proton transport in polymeric soft materials using a polymerizable molecular photoswitch. To this end, we design a merocyanine metastable-state photoacid, which we use as a building block to prepare a series of light-responsive polymers. We confirm the metastable character of the proposed monomer, and we elucidate its potential energy surface and the energies associated with its photoisomerization using quantum mechanical calculations. Interestingly, we found that when incorporated into a polymeric matrix, a photoacid loading effect impacts its photochromism and induces significant changes to the polymer nanostructure. Light stimulation of the films results in a reversible decrease in conductivity as the merocyanine simultaneously changes its net charge and functions as a photoacid by releasing protons, effecting switching as well as imparting proton conductivity to otherwise insulating polymers. We further exploit the commensurate changes to the polymer nanostructure to fabricate a light-driven hydrogel actuator. Our work establishes a versatile synthetic platform for the design of photo-modulated proton-conductive systems, offering new opportunities for responsive materials and iontronics applications.

The development of intelligent 3D printing materials with photo- and thermally responsive properties remains a challenge, particularly for sustainable applications requiring reprocessability, multifunctionality, and precise control over dynamic behaviors. Herein, we report a solvent-free photoprintable ink featuring dual dynamic covalent bonds (DCBs), designed for photo- and thermally responsive 3D printing. The resin combines dynamic disulfides and β-hydroxy esters, further enhanced with photoswitchable spiropyran additives, enabling tunable photochromic and thermochromic properties. This material also exhibits shape memory functionality, allowing simultaneous shape and color transitions under heat. Printed prototypes demonstrate exceptional thermal stability and multifunctionality, supporting applications in anticounterfeiting, imaging, and sensing. These results provide a sustainable and innovative solution for intelligent 3D printing materials, bridging the gap between multifunctionality and reprocessability. By advancing the capabilities of responsive materials, this work paves the way for transformative progress in adaptive manufacturing and practical applications in next-generation functional devices.

Efficient photoswitches capable of complete conversion to their metastable isomer are not so common, yet highly desirable for applications in smart materials and devices. Here, we report the photochromic behavior of a series of styryl cyanine photoswitches, all demonstrating high switching efficiency, with some achieving full conversion to the metastable form. Despite structural similarities to spiropyran photoswitches, we demonstrate that the photochemistry of styryl cyanines is fundamentally different. Unlike classical photoswitches that rely on double-bond rotation, these molecules undergo substantial geometric changes via the formation of a spiro carbon. This transformation disrupts conjugation, causing a desirable blue shift in absorbance ideal for creating responsive materials and devices. We further show that the switching kinetics can be finely tuned through electronic effects of various substituents or the choice of surrounding medium. These photoswitches exhibit excellent fatigue resistance and can be easily shifted into the visible region via their acidochromic properties. Taking advantage of their high switching efficiency and affinity for acidic polymers, we finally propose their use as smart dopants to develop light-responsive materials with tunable proton transport properties under visible light irradiation.

The amplification of molecular motion along length scales for macroscopic muscle-like functions, based on supramolecular polymers, provides attractive opportunities ranging from soft actuators to responsive biomedical materials. Taking the challenge to reveal dynamic assembly parameters governing muscle functions, we present the design of a photoswitch amphiphile based on an overcrowded alkene-derived core, and developed supramolecular artificial muscles. Going from molecular motor amphiphile (MA) to switch amphiphile (SA), taking advantage of high thermal stability of the switch core, a self-recovering of bent SA artificial muscle is observed in post-photoactuation without external intervention. Eliminating molecular motions in SA artificial muscle during the post-photoactuation and aging process enables us to identify correlations between dynamic assembly transformations and macroscopic actuating functions. These findings provide insights into photoactuation and subsequent self-recovery mechanisms from the aspect of dynamic assembly process, which offers new opportunities for developing amphiphile-based supramolecular artificial muscles.

The design of stimuli-responsive systems in nanomedicine arises from the challenges associated with the unsolved needs of current molecular drug delivery. Here, we present a delivery system with high spatiotemporal control and tunable release profiles. The design is based on the combination of an hydrophobic synthetic molecular rotary motor and a PDMS- b -PMOXA diblock copolymer to create a responsive self-assembled system. The successful incorporation and selective activation by low-power visible light (λ = 430 nm, 6.9 mW) allowed to trigger the delivery of a fluorescent dye with high efficiencies (up to 75%). Moreover, we proved the ability to turn on and off the responsive behavior on demand over sequential cycles. Low concentrations of photoresponsive units (down to 1 mol% of molecular motor) are shown to effectively promote release. Our system was also tested under relevant physiological conditions using a lung cancer cell line and the encapsulation of an Food and Drug Administration (FDA)-approved drug. Similar levels of cell viability are observed compared to the free given drug showing the potential of our platform to deliver functional drugs on request with high efficiency. This work provides an important step for the application of synthetic molecular machines in the next generation of smart delivery systems.

Natural systems transfer chiral information across multiple length scales through dynamic supramolecular interaction to accomplish various functions. Inspired by nature, many exquisite artificial supramolecular systems have been developed, in which controlling the supramolecular chirality holds the key to completing specific tasks. However, to achieve precise and non-invasive control and modulation of chirality in these systems remains challenging. As a non-invasive stimulus, light can be used to remotely control the chirality with high spatiotemporal precision. In contrast to common molecular switches, a synthetic molecular motor can act as a multistate chiroptical switch with unidirectional rotation, offering major potential to regulate more complex functions. Here, we present a light-driven molecular motor-based supramolecular polymer, in which the intrinsic chirality is transferred to the nanofibers, and the rotation of molecular motors governs the chirality and morphology of the supramolecular polymer. The resulting supramolecular polymer also exhibits light-controlled multistate aggregation-induced emission. These findings present a photochemically tunable multistate dynamic supramolecular system in water and pave the way for developing molecular motor-driven chiroptical materials.

Biological molecular machines enable chemical transformations, assembly, replication and motility, but most distinctively drive chemical systems out of-equilibrium to sustain life1,2. In such processes, nanometre-sized machines produce molecular energy carriers by driving endergonic equilibrium reactions. However, transforming the work performed by artificial nanomachines3-5 into chemical energy remains highly challenging. Here, we report a light-fuelled small-molecule ratchet capable of driving a coupled chemical equilibrium energetically uphill. By bridging two imine6-9 macrocycles with a molecular motor10,11, the machine forms crossings and consequently adopts several distinct topologies by either a thermal (temporary bond-dissociation) or photochemical (unidirectional rotation) pathway. While the former will relax the machine towards the global energetic minimum, the latter increases the number of crossings in the system above the equilibrium value. Our approach provides a blueprint for coupling continuous mechanical motion performed by a molecular machine with a chemical transformation to reach an out-of-equilibrium state.