Key Takeaways & Executive Findings
- •• • Covalent grafting of spiropyran (SP) at 1%, 2%, and 3% w/w onto naphthalimide-functionalized silica aerogels enables programmable fluorescence chromatic transitions from green (blue) to red via FRET, with response speed and color contrast suitable for time-dependent digital encryption. Industrial impact: provides a tunable platform for anti-counterfeiting labels with multiple security levels, reducing counterfeit risk by exponentially increasing decoding complexity. • • The aggregation-induced emission (AIE) of SP is harnessed by controlling amino group dispersion on the aerogel surface, which directly governs SP molecular packing and reversibly modulates red fluorescence. This spatial manipulation allows on-demand switching of emission, critical for dynamic information encryption where the signal must be toggled by external stimuli. • • A screen-printed QR code ink formulated with the composite and PVP remains invisible under ambient light but becomes scannable only after a specific UV exposure time, demonstrating a practical encryption protocol. This time-gated readout adds a temporal dimension to authentication, thwarting static copying and unauthorized scanning. • • The material exhibits fast response speed and strong contrast in color and fluorescence emission, but photostability is identified as a limitation requiring further improvement (Table S3). For industrial deployment, enhanced photostability is essential to ensure reliable long-term operation in security tags exposed to ambient light.
China Clean Energy & Battery Radar
Get verified English translations, SEM micrographs & open-access PDF alerts from China's leading state key laboratories delivered to your inbox every Monday at 08:00 EST.
Abstract
Dynamic fluorescent materials with stimulus-responsive emission modulation are pivotal for next-generation information security. This study presents a photoresponsive fluorescent composite system where spiropyran (SP) is covalently grafted onto naphthalimide-functionalized silica aerogel matrices. The architecture exhibits reversible fluorescence resonance energy transfer (FRET) between naphthalimide donors and merocyanine (MC) acceptors under ultraviolet irradiation, enabling dynamic emission shifting from green (blue) to red. Aggregation-induced emission (AIE) characteristics of SP are exploited to engineer a smart material system that reversibly regulates distinct red fluorescence by precisely controlling amino group dispersion on the naphthalimide-functionalized silica aerogels. This spatial manipulation governs the molecular packing state of SP, enabling dynamic fluorescence modulation. Programmable control over fluorescence chromatic transitions is achieved by systematically adjusting SP grafting densities (1%, 2%, and 3% w/w). A unique mode of dynamic information encryption technology is developed utilizing these dynamic fluorescence variations. The materials substantially enhance information encryption levels due to precisely adjustable fluorescence properties in response to external stimuli over time, making the encryption process unpredictable and complex, thereby exponentially increasing the difficulty for unauthorized replication or decoding. However, photostability requires further improvement (Table S3).
1. Introduction
Existing fluorescent anti-counterfeiting systems predominantly rely on static features, which are vulnerable to replication and offer limited encryption complexity. Dynamic fluorescent materials that respond to external stimuli, such as light, temperature, pH, ions, or force, have emerged to address these shortcomings by enabling time-dependent, multi-state optical signatures. Among these, photoresponsive organic systems incorporating photochromic switches like spiropyran (SP) are particularly attractive due to their remote controllability, non-destructive readout, and high spatiotemporal resolution. However, achieving precise control over fluorescence resonance energy transfer (FRET) between donor-acceptor pairs within a solid matrix remains a significant challenge, as it requires exact spatial organization and tuning of component interactions to ensure efficient and reversible energy transfer.
This study introduces a novel composite system where spiropyran is covalently grafted onto naphthalimide-functionalized silica aerogels, creating a robust platform for dynamic fluorescence modulation. By systematically varying the SP grafting density (1%, 2%, and 3% w/w), the material's fluorescence chromatic transitions are programmed, leveraging both FRET and aggregation-induced emission (AIE) mechanisms. This approach overcomes the limitations of static systems and provides a versatile route for advanced information encryption, including time-dependent digital encryption and UV-activated QR codes. The covalent grafting strategy ensures stable integration of the photochromic units, while the aerogel matrix offers high surface area and tunable porosity for controlled molecular dispersion.
Loading authentic research manuscript (Pages 1–5)...
WU Conghao, WU Wei, CAI Haitao, MEI Menghan, GAO Yangyang, WEI Youhao, ZI Yuanyuan, WANG Jingzhi, YANG Yuhui (2025). Dynamic Fluorescence Materials Based on Naphthalimide-Functionalized Silica Aerogels Covalently Grafted with Spiropyran: Applications in Advanced Information Encryption. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3359-4
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the photostability of the composite under continuous UV irradiation, and what degradation mechanisms are observed?
The paper explicitly states that photostability requires further improvement (Table S3). While specific degradation rates are not provided in the extracted text, the authors acknowledge this as a limitation. Industrially, photostability is critical for long-term anti-counterfeiting applications; without it, the material may lose its dynamic response after repeated UV exposure, compromising encryption reliability.
How does the grafting density of spiropyran (1%, 2%, 3% w/w) quantitatively affect the fluorescence color and intensity, and what is the optimal density for maximum contrast?
The study demonstrates that adjusting SP grafting density enables programmable control over fluorescence chromatic transitions. However, the extracted text does not provide quantitative color coordinates or intensity values. The optimal density likely balances FRET efficiency and AIE effects; higher densities may lead to aggregation-caused quenching, while lower densities may yield insufficient color change. Further quantitative analysis is needed for industrial optimization.
What is the response time of the fluorescence switching under UV exposure, and how does it compare to existing dynamic fluorescent materials?
The authors claim fast response speed as an advantage, but no specific response time (e.g., seconds, minutes) is given in the extracted text. For practical encryption, response time must be sufficiently short to allow on-demand readout. Comparative data with other systems would be necessary to assess competitiveness.
Can the composite be scaled up for industrial production, and what are the cost implications of using silica aerogels and covalent grafting?
The paper does not address scalability or cost. Silica aerogels are typically expensive to produce due to supercritical drying, and covalent grafting adds synthetic complexity. For commercial viability, alternative drying methods or cheaper matrices may be required. The use of PVP-based ink for screen printing suggests some scalability, but economic analysis is lacking.
What is the mechanism behind the AIE effect of spiropyran in this system, and how does the amino group dispersion on the aerogel control it?
The AIE effect arises from restricted intramolecular rotation of SP in the aggregated state, leading to enhanced red fluorescence. The amino groups on the naphthalimide-functionalized silica aerogel interact with SP, influencing its dispersion and packing. By controlling the amino group distribution, the aggregation state of SP is tuned, thereby modulating the AIE. This is a key design principle for reversible fluorescence switching.
Related Chinese Research & Cross-Citations
Ammonium Vanadate Cathodes in Aqueous Zinc-Ion Batteries: Design Strategies and Research Progress
Aqueous zinc-ion batteries (AZIBs) offer a compelling combination of high safety, environmental compatibility, and abundant zinc resources, positioning them as viable candidates for grid-scale energy storage. Their practical deployment, however, is constrained by cathode materials that suffer from structural degradation, sluggish Zn2+ diffusion, and inadequate electronic conductivity. Ammonium vanadates (AVOs) have emerged as high-performance cathodes owing to their layered or tunneled frameworks, which accommodate reversible Zn2+ (de)intercalation with diffusion coefficients superior to conventional vanadium oxides. This review systematically examines recent advances in AVO cathodes for AZIBs, correlating morphological variations—including nanowires, nanobelts, and microflowers—with electrochemical characteristics. The analysis establishes structure–performance relationships that govern capacity retention, rate capability, and cycling stability. Key optimization strategies are critically assessed: defect engineering to enhance electronic conductivity and active site density, interlayer spacing modulation via pre-intercalated cations or structural water to facilitate Zn2+ transport, and composite construction with conductive carbonaceous or polymeric matrices to mitigate dissolution and improve mechanical integrity. Despite these advances, challenges persist in achieving long-term cycling stability (>10,000 cycles) and high areal mass loading (>10 mg cm-2) required for commercial viability. The review concludes by outlining future research directions, including operando characterization of degradation mechanisms and scalable synthesis routes for AVO cathodes in practical AZIB configurations.
Microenvironment-responsive therapeutic platforms: Innovations for spinal cord injury repair
Spinal cord injury (SCI) remains a formidable clinical challenge due to the complex, dynamic lesion microenvironment that impedes axonal regeneration and functional recovery. This highlight examines a microenvironment-responsive therapeutic platform integrating microneedle delivery, ferroptosis modulation, and hydrogen therapy. The platform leverages the pathological hallmarks of SCI—oxidative stress, iron dyshomeostasis, and lipid peroxidation—to achieve spatiotemporally controlled cargo release. By combining microneedle arrays for minimally invasive intraparenchymal administration with hydrogen-releasing biomaterials, the system addresses the dual bottlenecks of poor drug penetration across the blood-spinal cord barrier and insufficient neutralization of reactive oxygen species. Ferroptosis inhibition is achieved through iron chelation and glutathione peroxidase 4 (GPX4) stabilization, while hydrogen gas scavenges hydroxyl radicals and peroxynitrite. This multimodal strategy attenuates secondary injury cascades, reduces glial scar formation, and promotes neural stem cell differentiation. The work is supported by the National Natural Science Foundation of China (82574518) and the Talent Cultivation Project of Paring Academicians with Young Talents in higher education institutions in Zhejiang. The authors declare no conflict of interest. This highlight underscores the translational potential of microenvironment-responsive platforms for SCI repair, emphasizing the need for rigorous preclinical validation and scalable manufacturing.
Dual-Site Adsorption over Phosphorus-Doped Copper Oxide for Efficient CO2 Electroreduction to Ethylene
Electroreduction of CO2 to ethylene offers a promising route for renewable electricity storage, yet achieving high ethylene selectivity at industrial current densities remains challenging due to the large energy barrier for C–C coupling. Here, we report a “MOF-assisted in situ doping” strategy to introduce the oxophilic nonmetal phosphorus (P) into the copper oxide (CuO) lattice, constructing a localized Cu–P dual-site adsorption configuration for the key *OCCHO intermediate. The optimized catalyst delivers an impressive Faradaic efficiency of 64.6% for ethylene with a partial current density of 646 mA cm-2. Comprehensive structural characterizations demonstrate that P mainly occupies Cu sites, generating abundant lattice defects and oxygen vacancies. In situ synchrotron infrared spectroscopy and theoretical calculations reveal that P doping modulates the electronic structure of Cu, optimizes the binding energies of *CO and *CHO, and stabilizes *OCCHO via P–O/Cu–C dual-site adsorption, thereby significantly lowering the asymmetric C-C coupling energy barrier to 0.74 eV. This work highlights a dual-site microenvironment regulation strategy for CO2-to-ethylene electroreduction.
Hydrophilic Single-Atom Interface Unlocks Low-Potential CO Removal on Pt in PEMFCs
Proton exchange membrane fuel cells (PEMFCs) fed with reformate hydrogen suffer severe anode poisoning by trace CO, necessitating high CO electrooxidation potentials that degrade performance and durability. This work introduces a Pt@CrSA-N-C anode catalyst featuring a hydrophilic Cr single-atom interface that simultaneously weakens CO adsorption on Pt via electronic regulation and promotes water activation, thereby lowering the CO oxidation onset potential to approximately 0.13 V vs. RHE. The onset potential was determined by two independent methods: the first potential at which the background-corrected current exceeds 0 mA cm-2 during CO oxidation reaction tests in a three-electrode system, and the potential at which the forward scan current exceeds the N2 background current in CO-stripping voltammetry. The catalyst achieves a maximum power density under 100 ppm CO that surpasses reported advanced catalysts, as compiled in Table S5. Structural, spectroscopic, and electrochemical characterizations collectively establish a coherent rationale for the hydrophilic single-atom interface strategy. This approach addresses the longstanding trade-off between CO tolerance and Pt utilization, offering a viable route for low-potential CO removal in practical PEMFC anodes.
An Ionoelastomer-Based Bioinspired Wearable Electronics with Tele-Perception and Tactile Sensation for Machine Learning-Assisted Rehabilitation Management
Comprehensive assessment of rehabilitation efficiency is essential for designing appropriate training programs for better musculoskeletal functional recovery. Existing contact-receptor-dependent rehabilitation assessment systems mostly focus on assessing the restoration of muscle function by evaluating grip strength or joint flexion angle; however, parameters reflecting neuromuscular synergistic function are always overlooked. Herein, we develop an ionoelastomer-based soft artificial electroreceptor (SAER) that integrates tele-perception and tactile sensation to track the rehabilitation process, collecting signals related to approaching speed and grip strength sequentially. The SAER uses polyurethane ionoelastomer incorporated with quasi-solid conductive salt as the electric field receptor, and is integrated on a rehabilitation-training ball after assembly to establish an untethered detection device; this enables the remote capture of hand approaching parameter within a 9 cm range, followed by the quantification of grip strength when contacting and grasping. Furthermore, a data-driven assessment system is established by integrating machine learning, which accurately classifies rehabilitation efficiency into six levels; it supports for rehabilitation evaluation and training programs adjustment. Overall, the SAER-based rehabilitation management system establishes a paradigm that synergistically evaluating parameters corresponding to neuromuscular functional restoration and holds strong potential for home-based active rehabilitation for minimizing dependence on frequent clinical supervision.
Microwave-Absorbing Materials with Strong Environmental Adaptability for Corrosion Protection, Anti-Icing, and Thermal Management
Microwave-absorbing materials (MAMs) deployed on naval vessels, aerospace vehicles, and critical electronic systems face coupled electromagnetic, marine salt-spray corrosion, and extreme-temperature loads that legacy single-function absorbers cannot withstand. This review consolidates progress on three environmentally adaptive MAM classes: corrosion-protective, anti-icing, and thermal-management absorbers. The electromagnetic loss and impedance-matching fundamentals are first established, then the synergistic mechanisms, design strategies, and characterization protocols for each class are examined against representative material systems and their measured performance. The analysis identifies a shared design logic—multiscale hierarchical architecture, interfacial polarization engineering, and multifunctional phase integration—while distinguishing the divergent protection mechanisms: barrier and passivation effects for corrosion, surface-energy and latent-heat regulation for anti-icing, and phonon–electron transport decoupling for thermal management. Persistent bottlenecks include the trade-off between impedance matching and protective-layer density, the absence of standardized coupled-field test protocols, and the scarcity of long-term salt-spray and thermal-cycling durability data. Future directions are delineated: intelligent self-adaptive absorbers, multiphysics-coupled simulation frameworks, and environmentally benign multifunctional integration. The review provides a theoretical and technical basis for the design, construction, and engineering scale-up of next-generation high-performance absorbers for aerospace, electronic, and marine equipment.