Restricted Motion Research Articles

A Liquid Crystal Polymer With Thermally‐Induced Deformation and Reversible Fluorescence Switching

AbstractStimuli‐responsive liquid crystal polymers (LCPs) hold significant promises as materials for designing multifunctional soft actuators. Recently, this group explored a novel strategy to develop a multi‐responsive LCP by combining ring‐opening metathesis polymerization (ROMP) with post‐polymerization modification (PPM). The current study aims to advance the approach to design an LCP capable of thermally‐induced deformation and fluorescence switching. ROMP is first employed to synthesize a reactive linear LCP precursor containing aggregation‐induced emission luminogens (AIEgens) with excellent processability, enabling the preparation of arbitrary shapes through various processing techniques. Subsequently, PPM is responsible for anchoring the mesogen alignment of the as‐prepared film and fiber geometries. The obtained cross‐linked LCP films and fibers undergo contraction, bending, unfolding and rolling with increasing temperature. Furthermore, the disruption of mesogen at high temperature weakens the restriction of AIEgen motions, facilitating the switching of the fluorescence property of LCPs. This material design combines the diverse fabrication opportunities, advanced actuation capabilities, and the tunable emission properties of AIEgens, while also enabling the visualization of the actuator's state.

Fluorescent Particles Based on Aggregation-Induced Emission for Optical Diagnostics of the Central Nervous System.

In 2001, Tang's team discovered a unique type of luminogens with substantial enhanced fluorescence upon aggregation and introduced the concept of "aggregation-induced emission (AIE)". Unlike conventional fluorescent materials, AIE luminogens (AIEgens) emit weak or no fluorescence in solution but become highly fluorescent in aggregated or solid states, due to a mechanism known as restriction of intramolecular motions (RIM). Initially considered a purely inorganic chemical phenomenon, AIE was later applied in biomedicine to improve the sensitivity of immunoassays. Subsequently, AIE has been extensively explored in various biomedical applications, especially in cell imaging. Early studies achieved nonspecific cell imaging using nontargeted AIEgens, and later, specific cellular imaging was realized through the design of targeted AIEgens. These advancements have enabled the visualization of various biomacromolecules and intracellular organelles, providing valuable insights into cellular microenvironments and statuses. Neurological disorders affect over 3 billion people worldwide, highlighting the urgent need for advanced diagnostic and therapeutic tools. AIEgens offer promising opportunities for imaging the central nervous system (CNS), including nerve cells, neural tissues, and blood vessels. This review focuses on the application of AIEgens in CNS imaging, exploring their roles in the diagnosis of various neurological diseases. We will discuss the evolution and conclude with an outlook on the future challenges and opportunities for AIEgens in clinical diagnostics and therapeutics of CNS disorders.

Intramolecular Aggregation‐Induced Surface Coupling of Metal Nanoclusters: Structure Elucidation and Photoluminescence Manipulation

ABSTRACTThe restriction of the molecular motion has been extensively exploited in tailoring the photoluminescence (PL) of metal nanoclusters, while the activation of such a restriction at the molecular level remains highly challenging. In this work, a two‐step strategy, that is, surface activating and surface coupling, was proposed to induce the restriction of the molecular motion of nanoclusters at the molecular level, and the corresponding nanoclusters underwent emission appearance and enhancement. The peripheral phosphine ligand functionalization and alkali metal cation introduction gave rise to a series of structural‐correlated M+‐incorporated Cu14 nanoclusters (M = Li, Na, K, Rb, Cs) with a surface‐aggregation characteristic, among which the K+‐participating nanocluster displayed the strongest fluorescence intensity in both solution and crystal states. Atomic‐level structure–property correlations were investigated to rationalize the PL comparisons. Overall, this work offers a new perspective for regulating the PL of metal nanoclusters via restricting their molecular motions, hopefully providing insight into the fabrication of highly emissive metal nanoclusters and cluster‐based nanomaterials.

The association between CHA2DS2-VASc score and aortic valve sclerosis.

Antithrombotic therapy in atrial fibrillation is generally managed with the CHA2DS2-VASc score. Aortic valve sclerosis (AVS) is a focal thickening of the aortic valve without a restriction of motion. AVS is related to several cardiovascular risk factors. Our study was performed to evaluate whether the presence of AVS was associated with the CHA2DS2-VASc score. This cross-sectional, observational study comprised 411 patients with AVS grades 1-3 [AVS (+)] and 102 patients with AVS grade 0 [AVS (-)]. We compared CHA2DS2-VASc scores between the AVS (+) and AVS (-) groups. We determined that the AVS (+) group had a higher CHA2DS2-VASc score than the AVS (-) group [3 (0-8) vs 1 (0-4), p < 0.001) ]. In our study, the CHA2DS2-VASc score was found to be higher in patients with AVS than in those without AVS. AVS may predict cardiovascular risk in the general population.

Amidine-functionalized aggregation-induced emission luminogen and a 3D-printed digital sensor platform for ultrafast and visual detection of heparin.

Heparin is a widely used anticoagulant in clinic. However, improper dosing can increase the risk of thromboembolic events, potentially leading to life-threatening complications. Clinic monitoring of heparin is very important for its use safety. Rapid and accurate point-of-care testing can significantly reduce the risk of thrombotic events. The detection of heparin using fluorescent probes has emerged as a significant area of research, driven by the need for rapid, sensitive, and selective methods for monitoring this crucial anticoagulant in clinical settings. However, the absence of convenient and user-friendly heparin testing methods continues to pose a challenge. In this work, a tetraphenylethylene derivatives with four amidine active groups (TPE-4+) was prepared. TPE-4+ has obvious aggregation-induced emission (AIE) effect on the heparin with a 127-fold enhancement occurring within just 3s. The molecular docking simulation showed that TPE-4+ was closely embedded in the heparin by the electrostatic force between four amidine of TPE-4+ and sulfate ester group of heparin, restricted intramolecular motion of TPE-4+, and causing obvious AIE features. The fluorescence intensity of TPE-4+ was line with the concentration of heparin in the range of 0-2.0 U/mL with a lowest detection limit of 0.0038 U/mL. The possible interference in the serum samples had no influence on the determination of heparin. Using 3D printing technology, a compact, portable digital sensor platform for straightforward monitoring of heparin levels was fabricated. The proposed innovative platform provides a powerful tool to make portable and real-time monitoring of heparin possible, and thereby contributing to achieve point-of-care testing and decrease the risk of thrombotic events. This novel method of combining the probe with the sensing platform simplifies the detection process and enhances patient care by providing more accurate diagnostic capabilities.

Mechano-Responsive Fluorescent Gel based on Tetraphenylethylene-Crosslinked Dynamic Covalent Network.

The rapid development of mechano-responsive fluorescence has been driven by its promising applications in the fields of sensors, information encryption, and anti-counterfeiting. However, designing mechanophores that can exhibit fluorescence changes under relatively low force remains challenging. In this study, a mechano-responsive fluorescent gel was developed using a tetraphenylethylene derivative as a cross-linker, producing a dynamic covalent network that exhibits increased fluorescence under tensile stress. Based on controlled experimental studies and molecular modeling calculations, the fluorescence enhancement by external forces was attributed to the restriction of intramolecular motion in tetraphenylethylene by macromolecular chain orientation. In time-dependent experiments, due to the exchange of dynamic covalent bonds, the stress relaxation and the decrease in fluorescence intensity of the gel at fixed strain occurred simultaneously, demonstrating the potential of this fluorescence as an indication of internal stress through aggregation-induced emission (AIE) type mechanophore.

Dynamics and Collective Behavior of Chemically Propelled Janus Sphere Dimers in Complex Solvents.

The propulsion mechanisms and collective dynamics of chemically powered Janus sphere dimers at the micro- and nanoscales, confined in a quasi-two-dimensional geometry, are investigated using a coarse-grained microscopic dynamical model. These active Janus dimers consist of two identical Janus spheres, featuring a catalytic cap on one hemisphere. The chemical reaction taking place on the catalytic surface generates asymmetric concentration gradients of product molecules around the Janus sphere, leading to the self-propulsion of the dimers. Depending on the dimer configuration, they exhibit various motion behaviors such as forward propulsion, rotation, and restricted stochastic motion. Due to chemotactic effects and self-diffusiophoretic forces, ensembles of dimers spontaneously form diverse structures, such as transient clusters, stable rotational ensembles, and antiparallel aligned doublets. This study demonstrates that the configurations of Janus sphere dimers significantly influence their self-propulsion and collective behaviors, providing crucial insights for the design and control of active micro- and nanoscale systems.

Excited State Dynamics of Geometrical Evolution of α-Substituted Dibenzoylmethanatoboron Difluoride Complex with Aggregation-Induced Emission Property.

Organic molecules with an aggregation-induced emission (AIE) property have been attracting much attention from the viewpoint of application to solid state emissive materials. For the AIE mechanism, quantum mechanical studies proposed the restriction of the intramolecular motion (RIM) model with the contribution of the conical intersection (CI) and deduced the importance of the restricted access to a conical intersection (RACI) in the potential energy surface (PES). Although these theoretical studies have contributed to the elucidation of AIE phenomena, direct detection of the reaction dynamics is indispensable to clarify the actual PES and the deactivation mechanism. Along this line, we investigated excited state dynamics of the AIE molecule with dibenzoylmethanatoboron difluoride complexes using time-resolved absorption spectroscopies in both visible and infrared (IR) regions. While the reference system of 1,3-bis(4-methoxyphenyl)methanatoboron difluoride (2aBF2) showed strong emission in solution, the methyl-substituted derivative at the α-position of the dioxaborine ring (2amBF2) led to the very weak fluorescence in solution but strong emission in the solid state. Time-resolved visible absorption measurements revealed a peak shift and broadening of the stimulated emission in the solution of 2amBF2, owing to the rapid change of the molecular geometry. With the temporal evolution of time-resolved IR absorption signals and density functional theory (DFT) calculation of these systems, it was deduced that 2amBF2 has two stable geometries, namely, planar and bending, in the S1 state and the bending geometry in the S1 state led to rapid conversion to the S0 state. These results support the RACI model in the aggregated states, leading to the AIE properties.

Hydrophobic forces at play: insights into AmelOBP4 and brood volatile interactions in Apis mellifera hygienic behavior

Understanding the intricate processes underlying olfaction necessitates unraveling the complexities of odorant binding protein’s interactions with volatile compounds triggering hygienic behavior in Apis mellifera, This study delves into the intricate processes of olfaction by focusing on the interactions between Apis mellifera Odorant Binding Protein 4 (AmelOBP4) and volatile compounds associated with hygienic behavior, employing a comprehensive computational approach. Molecular docking analyses reveal detailed binding interactions, emphasizing the significance of hydrophobic interactions and specific amino acid residues in stabilizing AmelOBP4-volatile complexes, notably with 2-nonacosanone (-8.4 kcal/mol) and hexacosyl acetate (-8.4 kcal/mol). Molecular dynamics simulations demonstrate sustained stability and principal component analysis affirms structural integrity through restricted global motions. Binding free energy calculations underscore robust interactions, with per-residue free energy decomposition identifying key amino acids contributing significantly to binding affinity. These findings illuminate the pivotal role of hydrophobic interactions and specific residues (Phe 60, Leu 83, Ile 116, Leu 126, and Leu 130) in modulating AmelOBP4-volatile interactions, providing foundational insights into volatile-based applications and potential olfactory response modulation, contributing to our understanding of olfactory processes.

Theoretical guiding with molecular docking for the screening of high-sensitive AIE probes for specific protein detection

The detection of proteins is crucial in the fields of disease diagnosis and drug development. Detection of proteins by aggregation-induced emission (AIE) probes is a quick and convenient method. However, the current AIE probes for the specific protein detection mainly depended on experimental test, lacking a guiding strategy. This study presented a novel approach to design AIE probes for detecting protein using molecular docking depending on AIE luminescence mechanism of the restriction of intramolecular motions. As an example to show its feasibility, three AIE probes with pyrrolo[3,2-b]pyrrole motif were designed and synthesized. The binding of the three probes to nine common proteins were predicted in advance using the molecular docking technique, obtaining information including intermolecular forces, binding energy, and binding sites between probes with proteins. The prediction results were verified through experimental data, and the mutual comparation of experimental and molecular docking results confirmed the reliability of the information provided by the molecular docking technique. Furthermore, the probes TPPP-2Na and TPPP-4Na exhibited limit of detection as low as 0.33 μg/mL for BSA and 0.35 μg/mL for HSA, respectively. The study revealed an innovative approach for the screening and molecular design of AIE probes for the detection of proteins.

Study of clinical and functional outcome of malleoli fracture

Background: Ankle fractures are a common orthopedic injury, accounting for 9% of all fractures, with an increasing incidence among both young and elderly populations. These fractures often result from road traffic accidents, falls, and sports injuries. Malleolar fractures, involving the bony prominences of the ankle, are particularly prevalent and necessitate accurate reduction and stable internal fixation to prevent complications such as post-traumatic arthritis and restricted motion. This study aims to assess the functional outcomes and results of surgical treatment of malleolar fractures. Methods: The study utilized Lauge-Hansen’s classification to analyze the mechanism of injury in 32 patients with ankle fractures. Surgical techniques included the fixation of syndesmotic injuries with anatomical fibular plates, (AFP) posterior malleolus fractures with percutaneous screws or Ellis plates, and medial malleolus fractures with tension band wiring (TBW). The outcomes were measured in terms of union time, range of motion, and stability. Results: The most common injury mechanism was supination external rotation (SER) in 14 patients, followed by pronation external rotation (PER) in 7 patients, pronation abduction (PAB) in 6 patients, and supination adduction (SAD) in 5 patients. Syndesmotic injuries were found in 7 patients, all treated surgically except one. Posterior malleolus fractures were present in 3 patients and treated with screws or plates. Fixation of medial malleolus fractures with TBW showed better union rates and improved range of motion compared to screw fixation. Lateral malleolar fractures treated with AFP provided additional stability. The average union time was 6 to 8 weeks. Conclusions: Anatomical reduction and stable internal fixation are crucial for the successful treatment of malleolar fractures. TBW for medial malleolus fractures and AFP for lateral malleolar fractures provide favorable outcomes. However, a larger sample size and longer follow-up duration are required to further evaluate the outcomes of ankle injuries, particularly in older patients with osteoporosis and comorbidities.

Split G-Quadruplex Programmed Recyclable AIE-Biosensor for Label-Free Detection of miRNA in Acute Kidney Injury.

We herein rationally designed a target-recyclable AIE-biosensor based on a split G-quadruplex for label-free detection of miRNA in acute kidney injury. Initially, the PG was in an "OFF" state, and the two split segments (G4-a and G4-b) of G4 were tethered at the two terminals of P1 and far away from each other due to the rigid duplex structure formed by the partially complementary intermediate sequences of P2 and P1, bringing MG with quenched fluorescence. In the presence of target, the 5'-PO4 P2 was displaced from PG probe and competitively hybridized with target, which led to G4-a and G4-b tending to form an intact intermolecular G-quadruplex, providing sites for MG intercalation, thus generating an activated "ON" fluorescence signal due to the restriction of intermolecular motion. Successively, relying on the λ-exonuclease (λ-Exo) cleavage reaction-assisted target recycling, more amounts of targets will be liberated, accompanied by forming more G-quadruplex and binding more MG, resulting in a strong fluorescence signal, further realizing the sensitive detection of the targets. As a proof of concept, miRNA-21 was chosen as the model target. Endowing with the precise target recognition and efficient cleavage activity of λ-Exo, the AIE-biosensor exhibited excellent detection sensitivity and specificity, which could quantitatively detect miRNA-21 down to 10.36 fM with a single mismatch specificity. The results revealed that the distinctive attributes of noninvasive, simple, and efficient in this G-quadruplex-based AIE-biosensor offered promising prospects for extensive applications in AKI screening and early clinical diagnosis.

AIEgens-based luminescent metal-organic frameworks as novel electrochemiluminescence emitters Integrated with co-reaction amplification strategy for CA15-3 detection

A current research focus in the field of electrochemiluminescence (ECL) is the development of novel high-performance emitters. Herein, we reported the synthesis of a zirconium-based metal–organic framework (Zr-TBAPy-MOF) using the aggregation-induced emission luminogens (AIEgens) 1,3,6,8-tetra(4-carboxyphenyl)pyrene (H4TBAPy) as ligands and Zr6-clusters as nodes. The resulting AIE-active luminescent MOF (AIE-LMOF) exhibited superior ECL properties and was used as an ECL emitter to construct a high-sensitivity ECL immunosensor. Conceptual experiments demonstrated that Zr-TBAPy-MOF showed significantly stronger ECL emission compared to both the monomers and aggregates of H4TBAPy, attributed to the effective restriction of intramolecular motion (RIM). On the sensor substrate, we designed an Au@ZnO/Cu2O nanocomposite as a co-reactant accelerator. This significantly promoted the generation of sulfate radicals (SO4•−) from persulfate (S2O82−) through the sustainable switching of Cu+/Cu2+ oxidation states in copper oxide (Cu2O). Additionally, zinc oxide (ZnO), which had excellent electrochemical properties, further enhanced the catalytic activity of the materials. Leveraging these advantages, we developed a sandwich-type ECL immunosensor for the ultrasensitive detection of carbohydrate antigen 15–3 (CA15-3), demonstrating a wide sensitive range (0.001 − 100 U/mL) and a low detection limit (0.0007 U/mL). Overall, this work paves the way for the development of efficient ECL luminophores with significant potential in the field of immunoassays for the early diagnosis of disease.

Size-Dependent Magnetic Responsiveness of a Photonic Crystal of Graphene Oxide Nanosheets.

A magnetically responsive photonic crystal of colloidal nanosheets can exhibit a controllable structural color, offering diverse potential applications. In this study, we systematically investigated how the lateral sizes of graphene oxide (GO) nanosheets affect their magnetic responsiveness in a photonic system. Contrary to the prediction that larger lateral sizes of nanosheets would be more responsive to an applied magnetic field based on the magnetic energy of anisotropic materials, we discovered that GO nanosheets with larger lateral sizes in the photonic system scarcely responded to a 12 T magnetic field. The lack of magnetic response may be due to the strongly restricted rotational motion of GO nanosheets by mutual electrostatic forces. In contrast, GO nanosheets with medium lateral sizes readily responded to the 12 T magnetic field, forming a uniaxially oriented structure that resulted in a vivid structural color. However, smaller GO nanosheets displayed a less vivid structural color, possibly because of less structural ordering of GO nanosheets. Finally, we found that the photonic crystal of GO nanosheets with optimized lateral sizes responded effectively to the 12 T magnetic field across various GO concentrations, resulting in a vivid and tunable structural color.

Design and analysis of a thick-panel origami-inspired soft crawling robot with multiple locomotion patterns

Abstract Due to the flexibility obtained through both materials and structures, soft robots have wide potential applications in complicated internal and external environments. This paper presents a new soft crawling robot with multiple locomotion patterns that integrate inchworm motion and various turning motions. First, the conceptual design of the proposed robot is presented by introducing thick-panel origami into the synthesis of a crawling robot, resulting in a Waterbomb-structure-inspired hybrid mechanism. Second, all locomotion patterns of the robot are precisely described and analyzed by screw theory in an algebraic manner, which include inchworm motion, restricted planar motion, quantitative turning motion, and marginal exploration motion. Then, the output motion parameter for each locomotion pattern is analytically modeled as a function of the robotic dimensional parameters, and the robot can thus be designed and controlled in a customized way for the expected output motion. Finally, the theoretical analysis and derivations are validated by simulation and physical prototype building, which lay the foundations for the design and manufacture of small-scale soft crawling robots with precise output motions in a complex planar environment.

Exploring the dynamics and interactions of the N-myc transactivation domain through solution nuclear magnetic resonance spectroscopy.

Myc proteins are transcription factors crucial for cell proliferation. They have a C-terminal domain that mediates Max and DNA binding, and an N-terminal disordered region culminating in the transactivation domain (TAD). The TAD participates in many protein-protein interactions, notably with kinases that promote stability (Aurora-A) or degradation (ERK1, GSK3) via the ubiquitin-proteasome system. We probed the structure, dynamics and interactions of N-myc TAD using nuclear magnetic resonance (NMR) spectroscopy following its complete backbone assignment. Chemical shift analysis revealed that N-myc has two regions with clear helical propensity: Trp77-Glu86 and Ala122-Glu132. These regions also have more restricted ps-ns motions than the rest of the TAD, and, along with the phosphodegron, have comparatively high transverse (R2) 15N relaxation rates, indicative of slower timescale dynamics and/or chemical exchange. Collectively these features suggest differential propensities for structure and interaction, either internal or with binding partners, across the TAD. Solution studies on the interaction between N-myc and Aurora-A revealed a previously uncharacterised binding site. The specificity and kinetics of sequential phosphorylation of N-myc by ERK1 and GSK3 were characterised using NMR and resulted in no significant structural changes outside the phosphodegron. When the phosphodegron was doubly phosphorylated, N-myc formed a robust interaction with the Fbxw7-Skp1 complex, but mapping the interaction by NMR suggests a more extensive interface. Our study provides foundational insights into N-myc TAD dynamics and a backbone assignment that will underpin future work on the structure, dynamics, interactions and regulatory post-translational modifications of this key oncoprotein.

Unexpected self-healing acceleration within urethane networks: lignosulfonate mediation of ionic and hydrogen bonds for ultra-strong recyclable elastomers

Stiff structures are generally considered detrimental to the materials’ self-healing efficiency because of the rigid conformation and restricted motion of the molecular chains. However, in this study, an unexpected acceleration in self-healing was observed in a urethane network when lignosulfonate, a bio-based stiff structure with stiff benzene rings, was introduced into the polyurethane matrix. An extraordinary increase in mechanical properties was achieved with just 3 wt% lignosulfonate added to the pristine sample, including a strength increase from 16.24 MPa to 42.89 MPa and elongation at break from 390% to 602%. Importantly, this significant enhancement in mechanical properties was accompanied by a notable acceleration in healing time efficiency, which increased by up to 44% compared to the pristine sample. This unique behavior can be attributed to the mediation of lignosulfonate on the ionic bonds between lignosulfonate and the urethane segment, as well as the hydrogen bonds formed within the urethane segments. This mediation ensures ultra-high strength without compromising the self-healing capacity and opens a way for accelerating elastomers self-healing efficiency through lignosulfonate, a readily available biomass-derived material. In addition, the addition of lignosulfonates gives the elastomer some Anti-UV performance.

Actin-driven nanotopography promotes stable integrin adhesion formation in developing tissue

Morphogenesis requires building stable macromolecular structures from highly dynamic proteins. Muscles are anchored by long-lasting integrin adhesions to resist contractile force. However, the mechanisms governing integrin diffusion, immobilization, and activation within developing tissues remain elusive. Here, we show that actin polymerization-driven membrane protrusions form nanotopographies that enable strong adhesion at Drosophila muscle attachment sites (MASs). Super-resolution microscopy reveals that integrins assemble adhesive belts around Arp2/3-dependent actin protrusions, forming invadosome-like structures with membrane nanotopographies. Single protein tracking shows that, during MAS development, integrins become immobile and confined within diffusion traps formed by the membrane nanotopographies. Actin filaments also display restricted motion and confinement, indicating strong mechanical connection with integrins. Using isolated muscle cells, we show that substrate nanotopography, rather than rigidity, drives adhesion maturation by regulating actin protrusion, integrin diffusion and immobilization. These results thus demonstrate that actin-polymerization-driven membrane protrusions are essential for the formation of strong integrin adhesions sites in the developing embryo, and highlight the important contribution of geometry to morphogenesis.

A comprehensive scoring system for the diagnosis and staging of adhesive capsulitis: development, application, and implications.

Adhesive capsulitis (AC), often referred to as frozen shoulder, presents a diagnostic challenge due to its insidious onset and progressive nature. The condition is characterized by pain and restricted motion in the shoulder, with a predilection for individuals between 40 and 60years of age. A novel scoring system was developed to enhance the accuracy of diagnosing AC and distinguishing between its stages, aiming to streamline clinical decision-making and treatment planning. A cohort of patients with symptoms suggestive of AC was assessed using the new scoring system, which integrates clinical, radiological, and patient history factors. Parameters included comorbidities like diabetes mellitus, recent immobility, rotator cuff tears, and specific ultrasound findings. Patients were scored and categorized into definitive AC, uncertain diagnosis, or exclusion from AC, with scores > 7, 6-2, and < 2, respectively. The scoring system effectively categorized patients, with those scoring > 7 demonstrating pronounced symptoms and ultrasound changes consistent with Phase 2 AC. Patients with scores between 6 and 2 were classified into uncertain Phase 1 or Phase 3, necessitating further observation. Scores < 2 effectively excluded AC, indicating a need to explore alternative diagnoses. The structured scoring system demonstrated potential as a comprehensive tool for diagnosing AC. By quantitatively assessing a range of contributory factors, it allowed for the stratification of the disease into distinct stages. This system is anticipated to improve early diagnosis and the precision of treatment interventions, although further validation in larger cohorts is warranted. II-III.

Unified Role of the 145th Residue on the Fluorescence Lifetime of Fluorescent Proteins from the Jellyfish Aequorea victoria.

Finding a unified fluorescence mechanism is essential to develop and utilize fluorescent proteins appropriately. Here, we report the unified role of the 145th residue on the fluorescence efficiency of fluorescent proteins developed from the jellyfish Aequorea victoria by demonstrating the difference and similarity between two representative fluorescent proteins, enhanced green fluorescent protein (eGFP), and enhanced yellow fluorescent protein (eYFP). We determined the fluorescence lifetimes of the 19 different Y145 mutants of eGFP and eYFP by picosecond time-resolved fluorescence spectroscopy. We found that the effect of the 145th mutation on the fluorescence lifetime is significant for eYFP but moderate for eGFP. We compared known crystal structures to clarify the observed difference between eGFP and eYFP. As a result, we conclude that the efficiency of the steric restriction of the chromophore motion by the 145th side chain is essentially the same for both eGFP and eYFP. Meanwhile, the restriction of the chromophore motion by hydrogen bonds is more pronounced for eGFP than for YFP. Balance of the steric effect and hydrogen bonding controls the lifetime of the Y145 mutants for eGFP and eYFP. Furthermore, the steric restriction is induced by the electrostatic effect; the different 145th residue induces a different electrostatic environment around the chromophore. The finding in this study reasonably explains the reported lifetimes of other fluorescent proteins and allows the prediction of the lifetime of unknown fluorescent proteins from jellyfish.