External Stimuli Research Articles

Chirality-controlled second-order nonlinear frequency conversion in lithium niobate film metasurfaces.

The high-quality factor resonant metasurfaces have extensive applications in enhancing nonlinear frequency conversion efficiency at the subwavelength scale. However, methods for actively modulating the frequency conversion process are limited. We design a chiral lithium niobate film metasurface and investigate the photonic spin as a new degree of freedom to dynamically control the second-order nonlinear frequency conversion, without reconfiguring the structure by using external stimuli. The chiral resonance with circular dichroism (CD) of 0.62 gives rise to a high nonlinear CD of 0.84 in second-harmonic generation efficiency. Interestingly, combining the chiral resonance and an achiral quasi-bound state in the continuum enables us to investigate the photonic-spin-controlled sum-frequency generation and the photon pair generation from the spontaneous parametric downconversion process. Owing to the ultrahigh quality factor exceeding 103 both for two resonances, the second-order nonlinear frequency conversion occurs at a wavelength region of 0.2 nm, suggesting good monochromaticity. Our work opens new, to our knowledge, avenues for practical implementation of dynamically controlled nonlinear optical devices and will find utility in holography, switchable light sources, and information processing.

Do fear-of-COVID-19 and regional identity matter for the linkage between perceived CSR and brand evangelism? A comparative analysis in South Asia

PurposeThere is a dearth of evidence on how and when perceived corporate social responsibility (PCSR) contributes to brand evangelism in the consumer behavioural literature, especially during a pandemic situation. In an attempt to examine this phenomenon, this study investigates the effect of fear-of-COVID-19 (Coronavirus disease 2019) and regional identity on PCSR and brand evangelism effect in the South Asian retail context. It theorises linkages mainly from behavioural inhabitation system theory and social identity theory.Design/methodology/approachA survey was administered to a representative sample of 2,242 retail consumers representing Sri Lanka, Bangladesh, Pakistan and India.FindingsThe results revealed a positive impact of PCSR on brand evangelism, but interestingly varying levels of strength of the key relationships based on country-wise fear-of-COVID-19 and regional identity during the pandemic.Practical implicationsFor the first time, the results of this research shed light on incorporating consumers’ regional identity as well as consumer fear as cultural predictors for better explaining the PCSR and brand evangelism link of nations within a region. This has implications for both theory and practice in the domain of consumer behaviour.Originality/valueThe study reflects its originality by revealing the relevance of country level social identity and negative emotions of nations that can manipulate the business results of corporate ethical responsiveness from a consumer culture theory perspective, especially during and just after a crisis. These results underlie what is active inside consumer black box by explaining as to what external stimuli drive consumer collective and moral mind set in a given culture. This adds to the body of knowledge on ethical consumption behaviour more specific to consumer–brand interaction in market crises.

Gelatin-Modified Bioactive Glass for Treatment of Dentin Hypersensitivity

When dentin is directly exposed to the oral cavity for various reasons, such as a lack of enamel on the tooth surface, external stimuli to the dentin often cause transient discomfort known as dentin hypersensitivity. In order to block the incoming stimulus signal, an ideal treatment is to induce the production of minerals to block the dentinal tubules. In this work, a dentin-desensitizing plugging material was prepared by modifying mesoporous bioactive glass with gelatin, the mineralization and desensitization effects of which were compared with Gluma in in vitro experiments. These experiments confirmed that gelatin-modified bioactive glass (MBG@PDA@Gel) is more effective than traditional desensitizing agents at blocking dentin tubules. Following the successful synthesis of MBG@PDA@Gel, as confirmed by scanning electron microscopy, transmission electron microscopy, and other tests, the treatment of demineralized dentin with MBG@PDA@Gel demonstrated that the dentinal tubules were tightly blocked under scanning electron microscopy. MBG@PDA@Gel induces minerals in deeper layers of dentinal tubules, promoting remineralization and forming a unified structure with the tubule blockage. Animal studies showed that MBG@PDA@Gel can remineralize demineralized dentin, and it is stable in the oral cavity and does not fall out. MBG@PDA@Gel not only enhances the biocompatibility of the nanoparticle but also results in an overall uniform and rapid remineralization of the demineralized dentin.

Architectural dissection of adhesive bacterial cell surface appendages from a "molecular machines" viewpoint.

The ability of bacteria to interact with and respond to their environment is crucial to their lifestyle and survival. Bacterial cells routinely need to engage with extracellular target molecules, in locations spatially separated from their cell surface. Engagement with distant targets allows bacteria to adhere to abiotic surfaces and host cells, sense harmful or friendly molecules in their vicinity, as well as establish symbiotic interactions with neighboring cells in multicellular communities such as biofilms. Binding to extracellular molecules also facilitates transmission of information back to the originating cell, allowing the cell to respond appropriately to external stimuli, which is critical throughout the bacterial life cycle. This requirement of bacteria to bind to spatially separated targets is fulfilled by a myriad of specialized cell surface molecules, which often have an extended, filamentous arrangement. In this review, we compare and contrast such molecules from diverse bacteria, which fulfil a range of binding functions critical for the cell. Our comparison shows that even though these extended molecules have vastly different sequence, biochemical and functional characteristics, they share common architectural principles that underpin bacterial adhesion in a variety of contexts. In this light, we can consider different bacterial adhesins under one umbrella, specifically from the point of view of a modular molecular machine, with each part fulfilling a distinct architectural role. Such a treatise provides an opportunity to discover fundamental molecular principles governing surface sensing, bacterial adhesion, and biofilm formation.

Neuroanatomical correlates of subjective tinnitus: insights from advanced cortical morphology analysis.

Subjective tinnitus, characterized by the perception of phantom sounds in the absence of external stimuli, presents significant challenges in both audiology and neurology. Once thought to primarily involve aberrant neural activity within auditory pathways, it is now understood to engage a broader array of neuroanatomical structures. This study investigated the connections between auditory, cognitive, and sensory processing regions, which are crucial for unraveling the complex neurobiological basis of tinnitus. Using high-resolution T1-weighted magnetic resonance imaging, we compared 52 individuals with subjective tinnitus with 52 age-matched healthy controls, focusing on cerebral cortex features, including fractal dimensionality, gyrification, and sulcal depth. Covariate analyses were conducted to explore the relationships between tinnitus duration, Tinnitus Handicap Inventory scores, anxiety score, and neuroanatomical changes. We found significant alterations in key brain regions involved in sensory processing, cognition, and emotional regulation, including the insula, lateral occipital cortex, middle frontal gyrus, and superior parietal lobule. These neuroanatomical changes were strongly correlated with the severity and chronicity of tinnitus symptoms. Our findings reveal profound structural changes in the brain associated with subjective tinnitus, offering valuable insights into the condition's underlying mechanisms and providing a potential framework for guiding future research and therapeutic interventions.

Plasmonic Nanocomposite for Visible Light‐Modulated Bimorph‐Actuator

AbstractSoft actuators have great potential applications in sophisticated movement and sensitive devices due to their flexible nature, good interaction, and precise control. However, existing carbon‐based optical actuators are limited in their response under visible light irradiation. The limited visible light absorbance of the carbon nanostructure brought the metallic nanoparticle into the soft actuators that can absorb visible light. This study introduces a new type of plasmonic photothermal‐bimorph actuator, using graphene oxide (GO), reduced graphene oxide (rGO), and silver nanorods (Ag NRs) to overcome the limitations of traditional optical actuators. The bimorph film is actuated by visible and near‐infrared light stimuli with various power densities showing reversible deformation behavior. The actuator shows significant bending associated with a ≈50° change in bending angle under visible light irradiation with a response time of ≈5 ± 1 sec. Furthermore, a smart photo‐controlled non‐contact switch is fabricated based on photo‐thermal conversion properties, demonstrating perfect integration of plasmonic bimorph actuators. The density functional theory based molecular dynamics calculations provide an additional understanding of the bending of actuators under external stimulus. Using illustrative demonstrations of actuators, these results hint at a method for generating multipurpose visible light‐based soft robots, supporting a new approach to developing an optical locking system.

Rapid Synthesis of Self‐Healing, pH‐Responsive IA‐Based Hydrogels via Frontal Polymerization

ABSTRACTSelf‐healing polymeric gels have emerged as a promising class of materials due to their ability to repair damage autonomously, offering significant advantages for various applications. Nevertheless, a major hurdle to their widespread practical use lies in their often‐compromised mechanical strength and long reaction time. Herein, we present the synthesis of a new type of self‐healing hydrogels using poly(itaconic acid‐co‐hydroxypropyl alcohol‐co‐acrylic acid), also known as poly(IA‐co‐HPA‐co‐AAc), by a frontal polymerization (FP) method. The rapid reaction rate of FP facilitates the swift and energy‐efficient synthesis of the hydrogels within 10 min, eliminating the need for prolonged reaction times. Additionally, the results revealed that the synthesized hydrogels exhibited pH‐dependent responsiveness, robust mechanical integrity, and autonomous self‐healing capabilities, obviating the requirement for external stimuli. The exceptional self‐healing properties can be attributed to the extensive hydrogen bonding network between the polymer chains, enabling them to recover up to 80% of their original mechanical strength. Rheological analysis confirmed the presence of a robust and stable gel network, evidenced by high storage modulus (G′) values across the entire frequency and strain sweep tests. This research addresses a significant knowledge gap in IA‐based hydrogels by introducing a rapid, optimized method for constructing self‐healing materials through hydrogen bonding interactions.

Hydrophobic Domain Modulation of Chemical Responsiveness in a Bolaamphiphile-Based Supramolecular Monomer.

Self-immolative chemistries that respond in an irreversible manner to external stimuli are highly attractive to permanently degrade filamentous supramolecular biomaterials. Within the monomer, a balance needs to be struck between its capacity to be supramolecularly polymerized and degraded at an appropriate rate for a given application. Herein, we unravel the structure-property-function relationships of a library of squaramide-based bolaamphiphiles bearing a central disulfide-based self-immolative spacer to construct supramolecular polymers responsive to chemical stimuli in aqueous solutions. We examine the impact of changing the alkyl domain length (2 to 12 methylene units) on the formation of supramolecular filaments and their rate of degradation in response to a biological antioxidant, glutathione. A minimum of an octyl spacer is required to robustly form supramolecular polymers that can be irreversibly degraded through a cyclization-elimination reaction of the self-immolative spacer triggered by thiol-disulfide exchange. Further increasing the peripheral alkyl chain length to a decyl spacer increases the ordered packing of the amphiphiles, hindering their chemical degradation. This study provides a framework to design chemically responsive filamentous supramolecular polymers based on bolaamphiphiles that can be irreversibly degraded in aqueous solutions for their eventual application as biomedical materials.

Luteolin alleviates cerebral ischemia/reperfusion injury by regulating cell pyroptosis.

This study aimed to clarify the roles and underlying mechanisms of luteolin in the progression of cerebral ischemia/reperfusion injury (CIRI). A mouse model of CIRI was established using the middle cerebral artery occlusion (MCAO) method, after which luteolin was administered. Subsequently, neuronal apoptosis and pyroptosis were measured and the brain tissues of each group were subjected to RNA sequencing. Luteolin alleviated MCAO-induced brain infarction, apoptosis, and pyroptosis. RNA sequencing identified 3,379, 2,777, and 3,933 differentially expressed genes (DEGs) in the MCAO vs sham, MCAO vs MCAO + luteolin, and MCAO + luteolin vs sham groups, respectively. The identified DEGs showed enrichment in multiple processes, including pattern specification, forebrain development, anion transport, leukocyte migration, regulation of cell-cell adhesion, and positive regulation of the response to external stimuli, as well as the calcium, PI3K-AKT, JAK-STAT, NF-kappa B, IL-17, cAMP, cGMP-PKG, and Wnt signaling pathways. In addition, Ccl2 and Angpt2 interacted more with the other top 30 DEGs with high interaction weights. Finally, RT-qPCR results showed that MCAO induction significantly up-regulated the expression of Stoml3, Eomes, and Ms4a15 and down-regulated Nms, Ttr, and Avpr1a; however, luteolin could partially reverse the expression caused by MCAO. Luteolin can alleviate brain infarction, apoptosis, and pyroptosis in CIRI, and may improve MCAO-induced CIRI by targeting the identified DEGs and their enriched pathways.

Unlocking Single-Particle Multiparametric Sensing: Decoupling Temperature and Viscosity Readouts through Upconverting Polarized Spectroscopy.

Upconverting particles (UCPs), renowned for their capability to convert infrared to visible light, serve as invaluable imaging probes. Furthermore, their responsiveness to diverse external stimuli holds promise for leveraging UCPs as remote multiparametric sensors, capable of characterizing medium properties in a single assessment. However, the utility of UCPs in multiparametric sensing is impeded by crosstalk, wherein distinct external stimuli induce identical alterations in UCP luminescence, hindering accurate interpretation, and yielding erroneous outputs. Overcoming crosstalk requires alternative strategies in upconverting luminescence analysis. In this study, it is shown how a single spinning NaYF4:Er3+, Yb3+ upconverting particle enables simultaneous and independent readings of temperature and viscosity. This is achieved by decoupling thermal and rehological measurements-employing the luminescence of thermally-coupled energy levels of Er3+ ions for thermal sensing, while leveraging the polarization of luminescence from non-thermally coupled levels of Er3+ ions to determine viscosity. Through simple proof-of-concept experiments, the study validates the capability of a single spinning UCP to perform unbiased, simultaneous temperature, and viscosity sensing, thereby opening new avenues for advanced sensing in microenvironments.

NompC regulates locomotion and touch sensation in Bactrocera dorsalis.

No mechanoreceptor potential C (NompC) is a major mechanotransduction channel with an important role in sensing of external mechanical stimuli by insects, which help these organisms to avoid injury and adapt to environmental changes. To explore the biological functions of NompC in Bactrocera dorsalis, a notorious agricultural pest, we successfully generated NompC knockout strains using clustered regularly interspaced small palindromic repeats (CRISPR) / CRISPR-associated nuclease 9 (Cas9) technology. BdorNompC knockout led to an adult lethal phenotype, with approximately 100% mortality at 3 d after eclosion. Morphological observation revealed that the legs and wings of BdorNompC knockout insects were deformed, while behavioral assays showed that the locomotion was impaired in both adults and larvae, relative to that of the wild-type strain. Moreover, BdorNompC knockout reduced gentle-touch response in larvae. These results suggest that BdorNompC is critical for B. dorsalis survival, and that this mechanosensation channel represents a potential new target for pest control agents. Our findings also represent novel evidence indicating that insect NompC is involved in modulating adult wing and leg morphology.

UV ozone‐modified Fe3O4‐PDMS film for solvent‐driven soft actuators with controlled and multi‐stable deformations

AbstractIn recent years, solvent‐driven actuators have been capable of controlling deformations in response to external stimuli. However, a magnetic polydimethylsiloxane (PDMS) composite film with magnetic properties is traditionally developed using the micro‐electro‐mechanical system process. Although it has general actuation deformation, the composite film suffers from the problems of actuation and control. Here, this is done by co‐mixing PDMS and ferrosoferric oxide (Fe3O4) then waiting for curing and then undergoing ultraviolet‐ozone (UVO) surface treatment. By adjusting the time and orientation of the UVO treatment, a series of solvent‐driven actuators with multiform steady‐state structures (e.g., mono/bistable helix) is proposed. In addition, the deformation of the composite film under different geometrical parameters and surface constraints was visually predicted by incorporating finite element analysis methods. In addition, the controlled deformations of the composite film (such as box‐like, folded, and so on) are carried out by self‐morphing design. Finally, four bionic applications are also proposed to demonstrate the practical use of soft actuators based on Fe3O4‐PDMS films in bionic robots. This work provides new strategies for designing and fabricating programmable and controllable soft actuators and lays the foundation for a wide range of smart material applications.

Azobenzene-Tagged Photopeptides Exhibiting Excellent Selectivity and Light-Induced Cytotoxicity in MCF-7 Cells over HeLa and A549.

The precise regulation of proteasome activity has become a focal point in current research, particularly its implications in cancer treatment. Bortezomib is used for treating multiple myeloma and is found to be ineffective against solid tumors. A spatiotemporal control over the proteasome is one of the solutions to resolve these issues using external stimuli, such as light. Thus, we designed and synthesized azobenzene-containing tripeptide vinyl sulfones 1, 2, 3, and 4, as the azobenzene moiety can impart E↔Z isomerism upon exposure to UV light. Further, the hydrophobicity of these peptides was fine-tuned by systematically varying the size of hydrophobic amino acids at the P1, P2, and P3 positions. The light-induced Z isomers of these photopeptides showed excellent cellular potency in HeLa, MCF-7, and A549 cell lines. Photopeptide 4 with valine at the proximal position, phenylalanine at P2, and leucine at the P1 positions exhibited 19.3- and 6.6-fold cellular potency in MCF-7 and A549 cells, respectively.

Comparison of iPSC-derived human intestinal epithelial cells with Caco-2 cells and human in vivo data after exposure to Lactiplantibacillus plantarum WCFS1

To investigate intestinal health and its potential disruptors in vitro, representative models are required. Human induced pluripotent stem cell (hiPSC)-derived intestinal epithelial cells (IECs) more closely resemble the in vivo intestinal tissue than conventional in vitro models like human colonic adenocarcinoma Caco-2 cells. However, the potential of IECs to study immune-related responses upon external stimuli has not been investigated in detail yet. The aim of the current study was to evaluate immune-related effects of IECs by challenging them with a pro-inflammatory cytokine cocktail. Subsequently, the effects of Lactiplantibacillus plantarum WCFS1 were investigated in unchallenged and challenged IECs. All exposures were compared to Caco-2 cells and in vivo data where possible. Upon the inflammatory challenge, IECs and Caco-2 cells induced a pro-inflammatory response which was strongest in IECs. Heat-killed L. plantarum exerted the strongest effect on immune parameters in the IEC model, while L. plantarum in the stationary growth phase had most pronounced effects on immune-related gene expression in Caco-2 cells. Unfortunately, comparison to in vivo transcriptomics data showed limited similarities, which could be explained by essential differences in the study setups. Altogether, hiPSC-derived IECs show a high potential as a model to study immune-related responses in the intestinal epithelium in vitro.

Genomics-driven integrative analysis highlights immune-related plasma proteins for psychiatric disorders

BackgroundGenome-wide association studies (GWAS) have identified numerous variants associated with psychiatric disorders. However, it remains largely unknown on how GWAS risk variants contribute to psychiatric disorders. MethodsThrough integrating two largest, publicly available, independent protein quantitative trait loci datasets of plasma protein and nine large-scale GWAS summary statistics of psychiatric disorders, we first performed proteome-wide association study (PWAS) to identify psychiatric disorders-associated plasma proteins, followed by enrichment analysis to reveal the underlying biological processes and pathways. Then, we conducted Mendelian randomization (MR) and Bayesian colocalization (COLOC) analyses, with both discovery and parallel replication datasets, to further identify protein-disorder pairs with putatively causal relationships. We finally prioritized the potential drug targets using Drug Gene Interaction Database. ResultsPWAS totally identified 112 proteins, which were significantly enriched in biological processes relevant to immune regulation and response to stimulus including regulation of immune system process (adjusted P = 1.69 × 10−7) and response to external stimulus (adjusted P = 4.13 × 10−7), and viral infection related pathways, including COVID-19 (adjusted P = 2.94 × 10−2). MR and COLOC analysis further identified 26 potentially causal protein-disorder pairs in both discovery and replication analysis. Notably, eight protein-coding genes were immune-related, such as IRF3, CSK, and ACE, five among 16 druggable genes were reported to interact with drugs, including ACE, CSK, PSMB4, XPNPEP1, and MICB. ConclusionsOur findings highlighted the immunological hypothesis and identified potentially causal plasma proteins for psychiatric disorders, providing biological insights into the pathogenesis and benefit the development of preventive or therapeutic drugs for psychiatric disorders.

THE NEUROBEHAVIORAL STATE HYPOTHESIS.

Since the early attempts to understand the brain made by Greek philosophers more than 2000 years ago, one of the main questions in neuroscience has been how the brain perceives all the stimuli in the environment and uses this information to implement a response. Recent hypotheses of the neural code rely on the existence of an ideal observer, whether on specific areas of the cerebral cortex or distributed network composed of cortical and subcortical elements. The Neurobehavioral State hypothesis stipulates that neurons are in a quasi-stable state due to the dynamic interaction of their molecular components. This increases their computational capabilities and electrophysiological behavior further than a binary active/inactive state. Together, neuronal populations across the brain learn to identify and associate internal and external stimuli with actions and emotions. Furthermore, such associations can be stored through the regulation of neuronal components as new quasi-stable states. Using this framework, behavior arises as the result of the dynamic interaction between internal and external stimuli together with previously established quasi-stable states that delineate the behavioral response. Finally, the Neurobehavioral State hypothesis is firmly grounded on present evidence of the complex dynamics within the brain, from the molecular to the network level, and avoids the need for a central observer by proposing the brain configures itself through experience-driven associations.

A semi-empirical parameter predicting the sensitivity of energetic materials from external pressure

Measuring the ability of a material to absorb energy from an external stimulus is crucial for understanding the sensitivity mechanism of energetic materials (EMs). Based on this, a semi-empirical parameter, M, is proposed to measure the material’s ability to absorb energy from an external stimulus, which is closely related to zero-point energy and volume. In this work, taking the external pressures (P) of 0.1 and 1.0 GPa as examples, we calculate the value of M for 16 EMs, and discuss the relationship between M and the impact sensitivity of EMs (E50). Considering the indispensable influence of molecular structure on the impact sensitivity of EMs, 16 EMs are divided into Groups A and B according to their structure whether contains a benzene ring. We find that the correlation between M0 and E50 when P is 0.1 GPa is less than that when P is 1.0 GPa. Therefore, the parameter M0 has been modified by adding the initial zero-point energy, and the modified parameter is referred to as M∗. The correlation between M∗ and E50 is further improved compared with M0. In particular, for Group B, the correlation between M∗ and E50 is good, where R2 is 0.95 and PCCs is 0.97 when P is 1.0 GPa, and R2 is 0.87 and PCCs is 0.92 when P is 0.1 GPa.

Internal heating and distribution in electromagnetic Powell-Eyring [formula omitted]/glycerin hybridized nanomaterial with radiation and wall slip conditions

The synergistic influences of the hybridization of molybdenum disulfide (MoS2) and graphene oxide (GO) nanoparticles on electromagnetic radiation absorption and augmentation of thermal conductivity coupled with the industrial demand for an enhanced non-Newtonian working fluid spurred this study. Therefore, the study examines the radiative properties and thermal behaviour of hybridized MoS2 and GO nanoparticle systems dispersed in a glycerin Powell-Eyring fluid with wall slip conditions. A theoretical mathematical setup is modelled for the nanoparticle thermophysical characteristics with viscous dissipation and heat generation under the influence of the electromagnetic Riga plate. The model is transformed into an invariant dimensionless form and solved utilizing the pseudo-spectral collocation technique. The effect of fluid rheology, nanoparticle concentration, and fluid-wall slip conditions interface on radiative heat transfer and thermal propagation is investigated. The results reveal momentous augments in radiation absorption and thermal conductivity of about 4.13% to 10.22% due to MoS2 and GO hybridized nanoparticles. Also, it was found that thermal transport is enhanced close to the solid boundary wall slip, leading to an improve heat distribution rate. Hence, this study contributes to the interplay complexity between external stimuli, fluid dynamics, and nanoparticle morphology in thermal systems, offering insights into the advanced materials synthesis, thermal management systems, and optimization and design of nanoparticle fluid enhancement applications.

Engineering PLA-MXene nanocomposite with balanced mechanical properties for enhanced shape memory effect

AbstractPoly(lactic acid) (PLA) as shape memory material has gained attention due to its biocompatibility, biodegradability, and ease of processing by 3D printing. PLA’s environmentally friendly nature makes it an attractive candidate for sustainable and recyclable shape memory applications. However, PLA’s slow shape recovery rate and low shape fixation percentage hinder its applicability as shape memory material. In the present study, we report MXene-modified PLA (PLA/Mx) nanocomposite with enhanced shape memory effect. Solution processing methods mediated the loading of the MXene in the PLA matrix. Different samples were prepared by varying the weight% of the MXene in the PLA matrix. The structure and morphology of samples were analyzed by XRD and TEM characterization. Thermogravimetric analysis was performed to measure the thermal stability of the composite. Compared with pure PLA, with MXene loading, the PLA/Mx composites show an increase in thermal. The shape recovery study on PLA/Mx samples used temperature as an external stimulus. The PLA/Mx composite exhibited a significantly improved shape memory effect than the PLA alone. The study exhibits that a shape memory effect can be improved by tuning the MXene additive loading in the PLA matrix. The material shape recovery effect was validated by fabricating the spiral structure. The fast shape recovery time 3s and shape fixation/recovery of > 95% was observed for 1 wt% of PLA/Mx. The PLA/Mx composite is expected to contribute significantly to implementing innovative shape memory applications, particularly in the biomedical field for sutures, controlled drug release, and minimally invasive devices.

Photoregulated Supramolecular Polymerization through Halogen Bonding

Supramolecular polymers are able to change their structure, morphology and function in response to external stimuli. However, controlling the independence of stimuli‐responses in these systems is challenging. Herein, we exploit halogen bonding (XB) as a reversible network element to regulate the photoresponsive and adaptive behavior of supramolecular polymers. To this end, we have designed a system comprising an amphiphilic XB acceptor with the ability to self‐assemble in aqueous media (OPE‐Py) and a molecule with a dual photoresponsive and XB donor function [(E)‐Azo‐I]. OPE‐Py self‐assembles in aqueous media into supramolecular polymers, which transform into nanoparticle assemblies upon co‐assembly with (E)‐Azo‐I. Interestingly, a third type of assembly (2D sheets) is obtained if OPE‐Py is treated with (E)‐Azo‐I and exposed to photoirradiation. At ambient conditions, both nanoparticles and 2D sheets remain invariant over time. However, heating dissociates the XB interactions present in both assemblies, resulting in their transformation to the original fiber‐like morphology of OPE‐Py. Thus, breaking the communication between self‐assembly and the stimuli‐responses upon heating restores the original state of the system, drawing parallels to feedback loops in programming language. This work broadens the still limited scope of XB in solution assemblies and paves the way for multifunctional adaptive supramolecular systems.