Ultralong phosphorescence cellulose with excellent anti-bacterial, water-resistant and ease-to-process performance

Facile preparation of full-color room temperature phosphorescence metal-organic framework via covalent ligand decoration

The preparation of full-color room temperature phosphorescence (RTP) metal-organic frameworks (MOFs) is attractive but remains challenging. Herein, it is demonstrated that heavy atom-free cyclodextrin MOFs (CD-MOFs) with full-color and long-lived intrinsic RTP can be achieved by CD ligand decoration. Arylboronic acids with various π conjugations are covalently anchored by γ-CD, in return, the B─O covalent bonds and hydrogen bonds jointly stabilize the triplet excitons of the arylboronic acid chromophores, leading to the longest lifetime of up to ca. 1.42 s and full-color afterglows including blue, green, and red of the decorated γ-CD. These decorated γ-CD derivatives are then linked by potassium ions to form a body-centered cubic crystalline structure, namely full-color RTP CD-MOFs. The smart RTP CD-MOFs also show excitation wavelength-dependent afterglows due to the formation of various emissive species. The CD-MOFs together with the γ-CD ligands are successfully applied in advanced dynamic information encryption and anticounterfeiting. This success paves the way for the development of ecofriendly and practical full-color RTP MOFs.

Poly(methyl methacrylate) Nanosphere-Based Photocrosslinked Hydrogels with Ultralong Phosphorescence Lifetimes for High-Precision 3D Printing

Hydrogel-based afterglow materials offer significant potential for broadening the application field of organic room-temperature phosphorescence (RTP) materials owing to their tissue-mimetic flexibility and superior biocompatibility. However, achieving a colorful and efficient RTP in a water-rich hydrogel environment remains challenging. Here, we present a general strategy to fabricate colorful and efficient RTP hydrogels by incorporating compact and hydrophobic nanospheres loaded with chromophores, synthesized via emulsion polymerization, into photocrosslinked hydrogels with oxygen barrier properties. The resultant hydrogel demonstrates a remarkably high water content of 94.6% and a maximum phosphorescence lifetime of up to 1697.0 ms, both significantly surpassing the relevant values of organic RTP hydrogels reported in prior studies. Furthermore, 3D RTP hydrogels with complex geometries and high precision are fabricated using digital light processing (DLP) 3D printing technology. This approach connects the RTP hydrogel and 3D printing fields for the first time, opening up substantial potential for advancing the applications of RTP materials.

A general strategy for self-healing elastomers with ultralong room-temperature phosphorescence

Integration of room-temperature phosphorescence (RTP) into elastic matrices with persistent segment motions to build RTP elastomers is a trend for future flexible sensors and stretchable optics, which remains a critical challenge. Here, we present a general approach to creating self-healing phosphorescent elastomers (HPEs) via dynamic B-O bonds, which ensure that various commercial phosphors achieve ultralong RTP in silicone rubber systems. The resulting HPEs exhibit remarkable RTP lifetimes (up to 2.679 s) under ambient conditions, surpassing all previously reported RTP elastomers. Notably, this general method affords HPE films with uniform RTP performance across areas ranging from 1 × 1 cm2 to 45 × 50 cm2, and even larger sizes. With the assistance of self-healing properties, HPEs can be easily structurally transformed from 2D to 3D models (e.g., plate film to Möbius ring). The HPEs have potential applications in multi-patterned displays and time-dependent encryption, and this work provides a general and scalable solution for the production of long-lived RTP elastomers.

Kinetic Insight into the Formation of Physically Robust Molecular Network in Cellulose Hydrogels

Sol-gel method unlocks the enormous potential of utilizing abundant and renewable cellulose resources. However, the molecular-level structural evolution during the cellulose gelation process is less well understood, bringing challenges for achieving high performance of cellulose hydrogels by regulating their molecular network. Herein, a fascinating journey is unveiled through time-resolved in situ techniques for the evolution of the hierarchical structure of cellulose from micro to molecular scale during the gelation process. The two-regime gelation mechanism of cellulose is proposed. Unexpectedly, it is discovered that the polarity of anti-solvents could effectively control the gelation kinetics and manipulate the molecular network of cellulose hydrogels. As a result, the performance of cellulose hydrogels can be purposefully customized, which are either robust and elastic, or tough and high-damping. Understanding the gelation mechanism of cellulose and its structural evolution kinetics unlocks the pathways to exceptional performance and multifunctionality, which will foster potential advances in sustainable cellulose-based hydrogels.

Tumor-Specific On-Site Activation of Cisplatin via Cascade Catalytic-Redox Reactions for Highly Efficient Chemo-Immunotherapy

The therapeutic efficiency of platinum drugs is always limited by low utilization, side effects, and Pt-resistance. Herein, a double-lock protected PtII nanomedicine named PtNP@Cu has been developed, which performs cascade unlocking of dechlorinated cisplatin (DP) via catalytic-redox reactions, thus achieving tumor-specific "on-site" activation of cisplatin (cDDP) in the nucleus accompanied with substantial induction of ferroptosis of cancer cells. This design avoids the premature release of active PtII species in normal cells or in the cytoplasm of cancer cells before reaching nucleus, thereby ensuring maximum amplification of Pt-DNA crosslinking with tumor-specificity. Meanwhile, substantial GSH depletion and ROS production induced by cascade catalytic-redox reactions results in ferroptosis of cancer cells, which further reduces GSH-mediated cDDP detoxification, overcomes Pt-resistance, and enhances immunogenicity, ultimately realizing highly efficient tumor-specific chemotherapy and antitumor immunity in vivo. This work provides a new strategy for effectively and comprehensively addressing the issues of low utilization, side effects, and drug resistance problems of platinum drugs, which is also promising for chemo-immunotherapy.

Bio-Based Thermoplastic Room Temperature Phosphorescent Materials with Closed-Loop Recyclability

Producing thermoplastic room temperature phosphorescent (RTP) materials with closed-loop recyclability from natural sources is an attractive approach but hard to achieve. Here, the study develops such RTP materials, Poly(TA)/Cell, by thermally polymerizing thioctic acid in the presence of cellulose. Specifically, polymerized thioctic acid poly(TA) forms strong hydrogen bonding interactions with CNF, promoting formation of molecular clusters between the oxygen-containing units. The as-formed clusters generate humidity- and excitation-sensitive green RTP emission. Red afterglow emission is also obtained by integrating Poly(TA)/Cell together with Rhodamine B (RhB) via an energy transfer process. Attributed to the thermoplastic properties, the as-obtained Poly(TA)/Cell can be thermally molded into flexible shapes with uncompromised RTP performance. Moreover, owing to the alkali-cleavable properties of the disulfide bond in Poly(TA)/Cell, thioctic acid and cellulose can be successfully recycled from Poly(TA)/Cell with a yield of 92.3% and 81.5%, respectively. As a demonstrator for potential utility, Poly(TA)/Cell is used to fabricate materials for information encryption.

Fabrication of advanced cellulose-based devices for solar desalination: A review

Materials derived from cellulose have attracted considerable attention as affordable substrates for solar desalination, contributing to the solution of the worldwide water crisis. These substances allow for exact control of structural features and improve light absorption in photothermal processes, promoting specific interactions between light scattering and reflection within their porous structure. Moreover, cellulose can be readily transformed into nano- and microporous forms, which enhances water transportation due to its inherent three-dimensional properties. This review examines the design and utilization of cellulose-based solar evaporators for desalination purposes. With benefits such as biocompatibility, environmental friendliness, economic viability, renewable nature, sustainability, and versatility for diverse designs, cellulose-derived materials are set to play a vital role in addressing global water issues.

Ionic liquid-mediated facile synthesis of porous cellulose/silica aerogel composites with improved thermal insulation

Lightweight, flame-retardant biomass aerogels with recyclable property are promising for thermal insulation. To improve the thermal insulation capabilities, silica aerogel (SA) is focused due to its nanoporous microstructure and inherent material characteristics, but major challenges remain in directly dispersing it in polymers meanwhile preserving its nanoporous structure. This study reports a simple method to stably disperse SA in cellulose solution using ionic liquid (IL) through a mechanical stirring-foaming process. Then the cellulose/SA composite aerogels and aerogel fibers with high thermal insulation could be prepared followed by the regeneration process. Abandoning traditional top-to-down diffusion of regeneration bath, an innovative bottom-to-top regeneration (BtTR) technique was utilized, leading to anti-gravity diffusion of water from the bottom to top of the as-foamed cellulose/SA solution, which prevented water-induced pressure that could result collapse of air bubble. After freeze-drying, we produced SA-reinforced thermal insulation cellulose-based aerogels with uniform pore morphology (322-329 μm) and low density (∼17 mgcm⁻³). And they also achieved a thermal conductivity of 0.034 Wm⁻¹K⁻¹, surpassing most reported cellulose-based aerogels (e.g., 0.039-0.045 Wm⁻¹K⁻¹). This study offers a new strategy to disperse SA in cellulose assisted by IL, which could be valuable for inspiring the design and construction of multifunctional aerogel materials for engineering applications.

Enhanced Room-Temperature Phosphorescence in Delignified Wood Through Combination with Pyrene-Based Materials

Organic room-temperature phosphorescent (RTP) materials, featured by their large Stokes shifts and long lifetimes, have garnered significant attention due to their promising applications in biophotonics and optoelectronics. However, the instability of their triplet states and their proneness to quenching in aerobic, room-temperature environments pose significant challenges. Herein, delignified wood (DW) is used as a porous substrate and applied heat to drive dehydration condensation between cellulose/hemicellulose hydroxyls and the phosphorescent chromophore 1-pyrenylboronic acid (Py-BOH). This reaction forms B─O bonds, anchoring Py-BOH in a rigid microenvironment created by hydrogenbonding in the DW pores, which restricts molecular thermal motion and facilitates the RTP emission, resulting in a lifetime of 340 ms for the target RTP-DW film. Furthermore, due to the susceptibility of the cellulose hydrogen-bond network to disruption by water molecules, the RTP-DW film is sensitive to water and exhibits repeatable stimulus-responsive behavior under water/thermal stimulation. This material can be processed into various luminous objects by directly cutting the wood film into different shapes or grinding it into powder and compounding it with polymers, thereby holding potential applications in luminous indication and anti-counterfeiting. The successful preparation of this (room-temperature phosphorescent-delignified wood)RTP-DW film will provide an effective pathway for achieving high-value utilization of wood resources.

An excitation-wavelength-dependent organic photoluminescent molecule with high quantum yield integrating both ESIPT and PCET mechanisms

Excitation wavelength-dependent (Ex-De) chromophores, which exhibit changes in spectral composition with varying excitation wavelengths, have garnered significant interest. However, the pursuit of novel photoluminescence (PL) mechanisms and high luminescence quantum yields is facing huge challenges. Here, we discover that the introduction of a spinacine moiety to 2-(2-hydroxy-5-methylphenyl)benzothiazole, a traditional excited-state intramolecular proton transfer (ESIPT) fluorophore, results in a novel Ex-De PL molecule. The luminescent color of this compound can be effectively modulated from greenish-blue to yellow-green by adjusting either the excitation wavelength or temperature. Transient absorption and spectroelectrochemistry spectra elucidate the underlying mechanism, demonstrating the roles of ESIPT and proton-coupled electron transfer (PCET). When embedded in a poly(vinyl alcohol) film, the composite exhibits remarkable Ex-De PL behavior, achieving absolute fluorescence quantum yields of 55.6% (λ ex: 396 nm) and 69.6% (λ ex: 363 nm), as well as phosphorescence at room temperature. These properties highlight its potential for multiple encryption features, enhancing its application in anti-counterfeiting technologies.

Water-Resistant Organic Room-Temperature Phosphorescence from Block Copolymers

Room-temperature phosphorescence (RTP) polymers have demonstrated significant potential for various applications due to their unique luminescent properties. However, most conventional RTP polymers are vulnerable to moisture and water, which can disrupt the hydrogen bonding network within the polymer and accelerate the non-radiative decay of triplet excitons of phosphors, leading to the quenching of RTP. Herein, we present a universal strategy to achieve water-resistant RTP polymers by designing amphiphilic block copolymers with microphase-separated structures. Specifically, the rigid hydrophilic phase, which is rich in carboxyl groups, forms hydrogen bonds that suppress non-radiative decay of the chromophores, resulting in RTP. Meanwhile, the hydrophobic phase effectively prevents water molecules from penetrating and disrupting the rigid polymer network. By combining the functions of both the hydrophilic and hydrophobic phases, the resulting RTP copolymers exhibit good water-resistant properties. Even after being immersed in water for one month, the copolymers maintain a green afterglow with a lifetime of 629 ms. Moreover, the water-resistant nature of these RTP polymers has also been demonstrated in potential applications of afterglow displays and anti-counterfeiting. This research offers valuable insights into the design of RTP materials with stability in aqueous environments and broadens the scope of their potential applications in diverse settings.

Achieving Room-Temperature Phosphorescence in Solution Phase from Carbon Dots Confined in Nanocrystals

Carbon dots (CDs) have attracted growing interest in the construction of room-temperature phosphorescent (RTP) materials. However, in the solution phase of CDs, it is still challenging to obtain efficient and stable phosphorescent emission due to the intense quenching effect by dissolved oxygen and solvent molecules. Herein, we report robust phosphorescence in the solution phase, achieved by encapsulating citrate-derived CDs into NaYF4 nanocrystals via a one-step method of high-temperature coprecipitation. Combined characterizations show that the triplet emission from CDs is related to the abundance of C=O in the CDs, the formation of ionic-bond networks around the CDs, and the spatial confinement and quenching inhibition effects of NaYF4 nanocrystals. Notably, the transition of CDs@NaYF4 from hydrophobicity to hydrophilicity can be easily achieved by simple surface modulation of NaYF4 nanocrystals, which allows the RTP of CDs to be maintained in either polar or nonpolar solvents. In addition, CDs@NaYF4 exhibits stable afterglow in different pH environments, suggesting its excellent stability. Finally, we demonstrated the application of CDs@NaYF4 in 3D printing, oily anti-counterfeiting patterns, and cell imaging. Our work can serve the controllable preparation of solution-phase RTP materials and their various applications.

Green fabrication of biodegradable films: Harnessing the cellulosic residue of oat straw

Agricultural biomass is a sustainable source for developing biodegradable film to address mounting plastic perils. This study aims to investigate the influence of CaCl2 concentration on the properties of lignocellulose-based biodegradable film produced from oat straw biomass. Lignocellulose is extracted from oat biomass, and a green technique is employed to solubilize it in ZnCl2 solution and crosslinked with varying CaCl2 concentrations (200 mM-800 mM) to make films. The films containing 800 mM CaCl2 concentration demonstrated the lowest moisture content (12.81 ± 0.81 %), water solubility (43.91 ± 0.42), water vapor permeability (4.96 ± 0.14 × 10-11 gm-1s-1Pa-1), visible light transmittance (53.27 ± 0.69 %), and moisture absorption (42.42 ± 1.32 %). The tensile strength has increased remarkably from 4.24 ± 0.76 to 17.24 ± 3.68 MPa due to increased CaCl2 concentration from 200 mM to 800 mM. They degraded up to 83 % in soil with 20 % moisture after 28 days. Overall, films made of lignocellulose from oat straw biomass films demonstrate high strength and moisture barrier capabilities, rendering them suitable for use as food packaging materials.

Mechanism of photoluminescence properties of lyocell fibers changing with crystallinity

Although there have been sporadic reports that the crystallinity of cellulose has a significant impact on photoluminescence (PL) properties, the degree and pattern of this effect have not been thoroughly explored and elucidated. Here, we assume that crystallinity is positively correlated with PL emission. Then, lyocell fiber (CLY), a common man-made cellulose fiber, is selected to solve the above problems by exploring the PL emission properties of different crystallinity systems. Through the comparison of PL and persistent room temperature phosphorescence (p-RTP) emission properties under different crystallinity of CLYs, it is found that crystallinity is the key factor determining the above emission properties. The change trend of quantum yields is determined by the crystallinity. Through molecular interaction analysis and theoretical calculation, it is found that hexamers have more red shifted emission than tetramers, and to be more advantageous for phosphorescence emission. These interesting phenomena can be reasonably explained by clustering-triggered emission (CTE) and crystallization-Induced Phosphorescence (CIP) mechanism. Furthermore, these findings, in turn, offer more fundamental implications to the underlying mechanism of nonconventional chromophores. More meaningful is that these results can be used as a theoretical reference for real-time monitoring of CLY or other natural fiber in the actual mercerizing process.

Polylactic Acid (PLA)-Based Persistent Room-Temperature Phosphorescence Polymer Nanoparticles for Bioimaging

Recent advancements have focused on developing nanoscale persistent room-temperature phosphorescence (pRTP) structures to expand their applicability in biomedical fields. Traditional fabrication methods typically produce surface-coated core-shell pRTP nanoparticles composed of nonbiocompatible pRTP emitters at very high concentrations in the core. To overcome this limitation, polymeric pRTP nanosystems have been presented in this study as a promising alternative by embedding RTP molecules within the biocompatible polymer matrix, thereby significantly reducing the required concentration of RTP molecules. These polymer nanoparticles were fabricated using a biocompatible poly(lactic acid) (PLA) matrix by an effective microemulsion-based method. They exhibited similar pRTP properties to the traditional nanoparticles, showing comparable long-lasting phosphorescence with a lifetime of 118 ms even when the phosphorescent molecule content is below 2%. Moreover, the pRTP polymer nanoparticles with excellent biocompatibility and stability demonstrate interesting reversible photoactivated pRTP properties. They have been successfully applied for in vivo imaging with a high signal-to-noise ratio (SBR) of 2061, maintaining strong and long-lived phosphorescent emissions even for 20 min. These results highlight a viable approach to advancing the pRTP technology for biological applications.

High-Performance Organic Ultralong Room Temperature Phosphorescence Based on Biomass Macrocycle

The pursuit of sustainable, high-performance organic ultralong room temperature phosphorescence (OURTP) materials with stimulus-responsive properties presents a significant and enticing yet formidable challenge. Herein, an efficient strategy to confining boric acid-based compounds into biomass macrocycle γ-cyclodextrin through multiple interactions is developed, enabling the construction of high-performance and multicolor OURTP doped systems. The synergistic effects of strong hydrogen bonding, C─O─B covalent cross-linking, and host-guest encapsulation significantly suppress non-radiative transition, culminating in an extraordinary lifetime and excellent phosphorescence quantum yield of 4.65 s and 32.8%, respectively, which are far superior to reported biomass RTP materials. Additionally, merging biomass macrocycle with phosphors contributes to multiple stimulus responses, overcoming the inherent limitations of degradation and recycling of organic RTP compounds, and dynamically modulating RTP signals through multiple-stimulus responses, achieving the integration of multifunctional dynamic data processing techniques. This work will provide a direction for new environmentally friendly and potentially commercially available stimulus-responsive OURTP materials.

Preparation of cellulose-based fluorescent aggregations with various morphologies and their microstructure-correlated fluorescence behavior

We provided an efficient method for preparing fluorescent materials with high specificity. Firstly, the cellulose-based aggregations with adjustable morphologies and sizes were obtained by cross-linking copolymerization and self-assembly. Then, after encapsulating the fluorescein isothiocyanate (FITC) into the hydrophobic microregions of the cellulose-based aggregations by ultrasound/dialysis method, a series of cellulose-based fluorescent aggregations with different morphologies was obtained. The flower-like, tentacle-like, microsphere, hollow sphere, coral-like and solid sphere fluorescent aggregations could be obtained by changing the mass ratio of cellulose to gelatin, the degree of alkylation and the length of the alkyl chain. Scanning electron microscope (SEM), Dynamic light scattering (DLS), UV-vis and Zeta potential confirmed the formation of the cellulose-based aggregations with different morphologies and sizes, which provided basis for the successful encapsulation of FITC. The flower-like fluorescent aggregation showed the maximum fluorescence intensity. This was due to the rigid structure of cellulose, electrostatic repulsion, hydrogen bonding, and the larger surface area in flower-like aggregation, which was conducive to inhibiting π-π stacking and hydrogen bonding interaction of FITC, thus promoting the electron radiative transition. Also, cellulose-based fluorescent aggregation could be processed into fluorescent fiber, coating and printing pattern, and had potential applications in information storage, scene warning, and special fiber.

Elucidating the mechanism behind the significant changes in photoluminescence behavior after powder compression into a tablet

Nonconventional luminogens have great potential for applications in fields like anti-counterfeiting encryption. But so far, the photoluminescence quantum yield (PLQY) of most of these powders is still relatively low and the persistent room temperature phosphorescence (p-RTP) emission is relatively weak. To improve their PLQY and p-RTP, pressing the powder into tablets has been preliminarily proven to be an effective method, but the specific mechanism has not been fully elucidated yet. Here, D-(+)-cellobiose has been chosen as the representative to study the problem. The results showed that the PLQY and p-RTP lifetimes of the tablet of D-(+)-cellobiose were improved compared to those of the powder. Using the mechanism of clustering-triggered emission (CTE) and theoretical calculations, it has been demonstrated that the enhanced molecular interactions after compression are the key reason, which result in the formation of cluster emission centers with stronger emission capabilities. And the combination of the powder and tablet has been proven to have application potential for advanced anti-counterfeiting encryption. The above results not only provide possible references for understanding the emission mechanism of small molecules and cellulose based emission materials, but also promote the process of more intuitive observation of emission centers for explaining emission mechanisms.

Regulating Triplet Excitons of Organic Luminophores for Promoted Bioimaging

Afterglow materials with organic room temperature phosphorescence (RTP) or thermally activated delayed fluorescence (TADF) exhibit significant potential in biological imaging due to their long lifetime. By utilizing time-resolved technology, interference from biological tissue fluorescence can be mitigated, enabling high signal-tobackground ratio imaging. Despite the continued emergence of individual reports on RTP or TADF in recent years, comprehensive reviews addressing these two materials are rare. Therefore, this review aims to provide a comprehensive overview of several typical molecular designs for organic RTP and TADF materials. It also explores the primary methods through which triplet excitons resist quenching by water and oxygen. Furthermore, we analyze the principal challenges faced by afterglow materials and discuss key directions for future research with the hope of inspiring developments in afterglow imaging.

Exploring and Anticipating the Applications of Organic Room-Temperature Phosphorescent Materials in Biomedicine and Dentistry

As popular materials, organic room-temperature phosphorescent (RTP) materials have been studied and developed in many fields. RTP materials have the characteristics of a high signal-to-noise ratio (SNR) and high reactive oxygen species (ROS) quantum yield, which can achieve clear bioimaging and efficient ability of anti-tumor and antibacterial, and have received extensive attention from researchers for imaging, tumor therapy, and antibacterial treatment. Moreover, owing to their flexible molecular structures and various synthesis systems and methods, it may be possible to design and synthesize materials according to individual physiologic environments of patients in medical applications, making bioimaging more accurate and greatly improving tumor and bacterial killing rates. So they have great development potential in the medical field. On the basis of introducing the mechanism of RTP materials that emit phosphorescence and generate ROS, this review summarizes the medical applications of RTP materials from three aspects-bioimaging, tumor treatment and antibacterial treatment-to provide a basis for their application in the field of stomatology.

Carboxymethylcellulose-based aggregation-induced emission antibacterial material for multifunctional applications

Polysaccharides are ubiquitous in nature, typically harmless, and highly compatible with various tissues in biomedical contexts. These properties make them attractive for use in multifunctional materials. In this study, the aggregation-induced emission (AIE) antibacterial material (PLOCMC) was successfully synthesized by carboxymethylcellulose (CMC) and ε-Poly-Lysine (ε-PL). PLOCMC exhibits not only the AIE property but also a room temperature phosphorescent (RTP) phenomenon. This dual emission behavior enhances its potential applications in chemical sensing and anti-counterfeiting. Notably, PLOCMC shows low cytotoxicity and exhibits antibacterial activity against typical Gram-positive and Gram-negative bacteria, making it a potent agent against a variety of bacterial strains. Additionally, PLOCMC demonstrates specific responsiveness to Fe3+ ions and nitrite, indicating its potential utility in food safety and monitoring applications.

A Polyphenol Decorated Triplex Hybrid Biomaterial: Structure-Function, Release Profiles, Sorption, and Antipathogenic Effects

Herein, nonwoven alkali modified flax substrates were coated with incremental levels of chitosan, followed by immobilization of tannic acid, via a facile "dip-coating" strategy to yield a unique hierarchal "triplex" hybrid biomaterial, denoted as "THB". The characterization of the physicochemical properties of THB employed complementary spectroscopic (IR, Raman, and NMR) techniques, which support the role of hydrogen bonding and electrostatic interactions between the components: chitosan as the secondary biopolymer coating and the tertiary adsorbed polyphenols. XRD and SEM techniques provide further structural insight that confirms the unique semicrystalline nature and porous hierarchal structure of the biocomposite. The THBs present a polyphenol kinetic release profile that follows the Korsmeyer-Peppas model that concurs with Fickian diffusion for heterogeneous polymer systems. Furthermore, these systems demonstrate a tailored solvent uptake capacity (up to 4 g/g) in aqueous PBS media. Antipathogenic activity tests revealed 95% elimination of pathogens (E. coli, S. aureus, and C. albicans) at a dose of 50 mg for the THB system. The trend in the structure-property relationships for the THB systems indicates synergistic effects of electrostatic multiform interactions between protonated chitosan and the polyphenol units. Herein, we report the first example of a unique hierarchal biomaterial via a facile design strategy for diversiform roles as responsive adsorbents for environmental remediation to biomedical applications (e.g., controlled release, topical administration, or antimicrobial surface coatings).

De novo design of type-l photosensitizer agents based on structure-inherent low triplet energy for hypoxia photodynamic therapy

Photodynamic therapy (PDT), owing to its low invasiveness, high efficiency, fewer side effects, spatiotemporal controllability and good selectivity, has attracted increasing attention for its tremendous potential in revolutionizing conventional strategies of tumor treatment. However, hypoxia is a common feature of most malignancies and has become the Achilles' heel of PDT. Currently, Type II photosensitizers (PSs) have inadequate efficacy for PDT due to the inherent oxygen consumption of the anoxic tumor microenvironment. Moreover, due to the absence of a general molecular design strategy and the limitations imposed by the energy gap law, Type-I PSs are less reported. Therefore, the development of Type-I PSs with hypoxia resistant capabilities is urgently required. Herein, in this study, we have obtained pure Type-I materials for the first time by employing a strategy that decreases the triplet energy levels of the π-conjunction bridge. A sufficient donor-acceptor interaction reduces the lowest triplet energy level and aids in the transfer of excitons from singlet to triplet levels. With this strategy, dibenzofulvene derivatives (FEs) displayed purely Type-I ROS generation. Among them, FE-TMI exhibits superior Type-I reactive oxygen species-generation performance, showcasing the great potential of PDT in treating tumor cells under hypoxic conditions and several types of solid tumors in mouse in vivo experiments. This work provides a practical solution for the future design of Type-I PDT materials and is aimed at enhancing PDT efficiency.

Superhydrophobic microporous membrane based on modified microfibrillated cellulose framework for efficient oil-water separation

The preparation of stable and efficient cellulose-based oil/water separation membranes is of great significance in solving the problem of industrial oily wastewater. Herein, rod-like hydroxyapatite (HAP) modified microfibrillated celluloses (MFCs) are used to form the fibrous framework to produce a microporous PDMS-MFC-HAP membrane. The membrane shows good superhydrophobicity with a water contact angle of 151.6°. It exhibits the oil-water separation performance for various water-in-oil emulsions. The separation flux of the membrane is up to 3665.3 L·m-2·h-1·bar-1 under 0.5 bar pressure with a separation efficiency of over 99.6 %. The PDMS-MFC-HAP membrane could maintain a high separation efficiency of 98.6 % after 20 cycles. This study provides a simple and effective method to fabricate cellulose-based superhydrophobic membranes, which have a greater potential to achieve oil-water separation for oily wastewater treatment with high efficiency.

Xylan-based full-color room temperature phosphorescence materials enabled by imine chemistry

Developing sustainable matrix and efficient bonding mode for preparing room temperature phosphorescence (RTP) materials with full-color afterglows is attractive but still challenging. Here, xylan, a hemicellulose by-product from the paper mill, is used to construct full-color RTP materials based on imine bonds. Xylan is oxidation by periodate to introduce aldehyde groups to increase reaction sites; aromatic amines with different π conjugations can be readily anchored to dialdehyde xylan (DAX) by imine chemistry. The dual rigid environments were constructed by hydrogen bonding and imine covalent bonding, which can facilitate the triplet population and suppress non-radiative transitions, thus the xylan derivatives display satisfactory RTP performances. As the degree of conjugation of the chromophore increases, the afterglow colors can be changed from blue to green, yellow, and then to red. Thus, such a universal, facile, and eco-friendly strategy can be used to fabricate full-color RTP materials, which show a bright future in information encryption and advanced anti-counterfeiting. These results unambiguously state that the biodegradable paper mill waste-based RTP materials are convincingly expected to replace and surpass petroleum polymer-based counterparts.

Investigation of silicon doped carbon dots/Carboxymethyl cellulose gel platform with tunable afterglow and dynamic multistage anticounterfeiting

The remarkable optical properties of carbon dots, particularly their tunable room-temperature phosphorescence, have garnered significant interest. However, challenges such as aggregation propensity and complex phosphorescence control via energy level manipulation during synthesis persist. Addressing these issues, we present a facile gel platform for tunable afterglow materials. This involves chemically cross-linking biomass-derived silicon-doped carbon dots with carboxymethylcellulose and incorporating non-precious metal salts (BaCl2, CaCl2, MgCl2, ZnCl2, ZnBr2, ZnSO4) to enhance phosphorescence. Metal salts boost intersystem crossing via spin-orbit coupling, elevating triplet state transitions and activating phosphorescence. Chemical bonding and salt-induced coordination/electrostatic interactions establish confinement effects, suppressing non-radiative transitions. Diverse salt-gel interactions yield gels with tunable phosphorescence lifetimes (9.48 ms to 32.13-492.39 ms), corresponding to afterglow durations ranging from 3.20 to 11.86 s. With its broad tunability and high recognition, this gel material exhibits promising potential for dynamic multilevel anti-counterfeiting applications.

High-Value Utilization of Cellulose: Intriguing and Important Effects of Hydrogen Bonding Interactions─A Mini-Review

Cellulose has been widely used in papermaking, textile, and chemical industries due to its diverse sources, environmental friendliness, and renewability. Recently, much more attention has been paid to converting cellulose into high-value-added products. Therefore, the extraction of nanocellulose, the dissolution of cellulose, and their applications are some of the most important research topics currently. However, cellulose's dense hydrogen bond network poses challenges for efficient extraction and dissolution, limiting its potential for functional material development. This review discusses the mechanisms of hydrogen bond disruption and weak interactions during nanocellulose extraction and cellulose dissolution. Key challenges and future research directions are highlighted, emphasizing developing efficient, ecofriendly, and cost-effective methods. Additionally, this review provides theoretical insights for constructing high-performance cellulose-based materials.

Ultralong luminescence lifetime imaging of edible plant tissue for humidity sensing in food packaging by a smartphone

The safety of luminescence sensors and probes used in food packaging should be seriously considered, while most luminescence sensors were artificially synthesized with unclear toxicity, and cannot be directly used as indicators that were in contact with food. To overcome this problem, a humidity indicator based on an edible plant tissue was developed without any chemical processing. We found that garlic bulbs could emit significant persistent luminescence after drying at room temperature. The luminescence lifetime decreases from hundreds of milliseconds to tens of milliseconds as humidity increases. The long-lived luminescence could easily be detected through smartphones without any sophisticated instruments. The edible garlic is expected to be used as a humidity indicator in food packaging without worrying about food safety. Furthermore, the interference of scattered light and short-lived fluorescence from foods and packages can be eliminated in time-resolved luminescence imaging, greatly increasing the signal-to-noise ratio.

Halogen Engineering Strategy-Induced Color-Tunable Room Temperature Phosphorescence in Metal-Organic Halides

Color-tunable room temperature phosphorescence (RTP) materials possess potential applications in multicolor imaging, multichannel anticounterfeiting, and information encryption. Herein, we synthesized two zero-dimensional cadmium-organic halides, (H-aepy)2CdX4 (referred to as CdX-aepy; X = Cl-, Br-; aepy = 3-(2-aminoethyl)pyridine), both of which exhibit long-lived excitation wavelength- and time-dependent RTP. Experimental and theoretical results suggest that the multicolor RTP can be ascribed to the coemission of pristine H-aepy ligands and halogen-affected H-aepys, supporting that suitably introducing halogens can be an efficient strategy for constructing multicolor RTP materials. Additionally, we also demonstrate that the two phosphors can be applied in multichannel anticounterfeiting and information encryption. This work reports two hybrids with color-tunable RTP, as well as provides new insight into the effect of halogens on the regulation of RTP.

Room Temperature Phosphorescent Nanofiber Membranes by Bio-Fermentation

Stimuli-responsive materials exhibiting exceptional room temperature phosphorescence (RTP) hold promise for emerging technologies. However, constructing such systems in a sustainable, scalable, and processable manner remains challenging. This work reports a bio-inspired strategy to develop RTP nanofiber materials using bacterial cellulose (BC) via bio-fermentation. The green fabrication process, high biocompatibility, non-toxicity, and abundant hydroxyl groups make BC an ideal biopolymer for constructing durable and stimuli-responsive RTP materials. Remarkable RTP performance is observed with long lifetimes of up to 1636.79 ms at room temperature. Moreover, moisture can repeatedly quench and activate phosphorescence in a dynamic and tunable fashion by disrupting cellulose rigidity and permeability. With capabilities for repeatable moisture-sensitive phosphorescence, these materials are highly suitable for applications such as anti-counterfeiting and information encryption. This pioneering bio-derived approach provides a reliable and sustainable blueprint for constructing dynamic, scalable, and processable RTP materials beyond synthetic polymers.

Photoactivated room temperature phosphorescence from lignin

Sustainable photoactivated room temperature phosphorescent materials exhibit great potential but are difficult to obtain. Here, we develop photoactivated room temperature phosphorescent materials by covalently attaching lignin to polylactic acid, where lignin and polylactic acid are the chromophore and matrix, respectively. Initially the phosphorescence of the lignin is quenched by residual O2. However, the phosphorescence is switched on when the residual oxygen is consumed by the triplet excitons of lignin under continuous UV light irradiation. As such, the lifetime increases from 3.0 ms to 221.1 ms after 20 s of UV activation. Interestingly, the phosphorescence is quenched again after being kept under an atmosphere of air for 2 h in the absence of UV irradiation due to the diffusion of oxygen into the materials. Using these properties, as-developed material is successfully used as a smart anti-counterfeiting logo for a medicine bottle and for information recording.

3D Printed Room Temperature Phosphorescence Materials Enabled by Edible Natural Konjac Glucomannan

Shaping room temperature phosphorescence (RTP) materials into 3D bodies is important for stereoscopic optoelectronic displays but remains challenging due to their poor processability and mechanical properties. Here, konjac glucomannan (KGM) is employed to anchor arylboronic acids with various π conjugations via a facile B─O covalent reaction to afford printable inks, using which full-color high-fidelity 3D RTP objects with high mechanical strength can be obtained via direct ink writing-based 3D printing and freeze-drying. The doubly rigid structure supplied by the synergy of hydrogen bonding and B─O covalent bonding can protect the triplet excitons; thus, the prepared 3D RTP object shows a striking lifetime of 2.14 s. The printed counterparts are successfully used for 3D anti-counterfeiting and can be recycled and reprinted nondestructively by dissolving in water. This success expands the scope of printable 3D luminescent materials, providing an eco-friendly platform for the additive manufacturing of sophisticated 3D RTP architectures.

Revisiting various mechanistic approaches for cellulose dissolution in different solvent systems: A comprehensive review

The process of dissolving cellulose is a pivotal step in transforming it into functional, value-added materials, necessitating a thorough comprehension of the underlying mechanisms to refine its advanced processing. This article reviews cellulose dissolution using various solvent systems, along with an in-depth exploration of the associated dissolution mechanisms. The efficacy of different solvents, including aqueous solvents, organic solvents, ionic liquids, hybrid ionic liquid/cosolvent systems, and deep eutectic solvents, in dissolving cellulose is scrutinized, and their limitations and advantages are highlighted. In addition, this review methodically outlines the mechanisms at play within these various solvent systems and the factors influencing cellulose solubility. Conclusions drawn highlight the integral roles of the degree of polymerization, crystallinity, particle size, the type and sizes of cations and anions, alkyl chain length, ionic liquid/cosolvent ratio, viscosity, solvent acidity, basicity, and hydrophobic interactions in the dissolution process. This comprehensive review aims to provide valuable insights for researchers investigating biopolymer dissolution in a broader context, thereby paving the way for broader applications and innovations of these solvent systems.

Achieving Bright and Long-Lived Aqueous Room-Temperature Phosphorescence of Carbon Nitrogen Dots Through In Situ Host-Guest Binding

The development of bright and long-lived aqueous room-temperature phosphorescent (RTP) materials holds paramount importance in broadening the application scope of RTP material system. However, the conventional RTP materials usually exhibit low efficiency and short lifetime in aqueous solution. Herein, an in situ host-guest strategy is proposed to achieve cyanuric acid (CA)-derived phosphorescent carbon nitrogen dots (CNDs) composite (CNDs@CA) that demonstrates a significant enhancement of both quantum yield (QY) and lifetime mediated by water. Detailed investigations reveal that the robust hydrogen bonding networks between CNDs@CA and water effectively stabilize triplet excitons and suppress nonradiative decays, as well as facilitate efficient energy transfer from CA to CNDs, thereby prolonging the lifetime and enhancing the efficiency of RTP. The phosphorescent QY and lifetime of CNDs@CA can be increased to 26.89% (3.9-fold increase) and 951.25 ms (5.5-fold increase), respectively, with the incorporation of 50 wt% water under ambient conditions. Even in fully aqueous environments (with up to 400 wt% water added), CNDs@CA exhibits persistent water-boosted RTP properties, demonstrating exceptional stability. The robust water-boosted RTP property of CNDs@CA in aqueous solutions presents significant potential for high signal-to-noise ratio afterglow bioimaging as well as advanced information encryption.

Finely manipulating room temperature phosphorescence by dynamic lanthanide coordination toward multi-level information security

Room temperature phosphorescence materials have garnered significant attention due to their unique optical properties and promising applications. However, it remains a great challenge to finely manipulate phosphorescent properties to achieve desirable phosphorescent performance on demand. Here, we show a feasible strategy to finely manipulate organic phosphorescent performance by introducing dynamic lanthanide coordination. The organic phosphors of terpyridine phenylboronic acids possessing excellent coordination ability are covalently embedded into a polyvinyl alcohol matrix, leading to ultralong organic room temperature phosphorescence with a lifetime of up to 0.629 s. Notably, such phosphorescent performance, including intensity and lifetime, can be well controlled by varying the lanthanide dopant. Relying on the excellent modulable performance of these lanthanide-manipulated phosphorescence films, multi-level information encryption including attacker-misleading and spatial-time-resolved applications is successfully demonstrated with greatly improved security level. This work opens an avenue for finely manipulating phosphorescent properties to meet versatile uses in optical applications.

Isostructural doping for organic persistent mechanoluminescence

Mechanoluminescence, featuring light emission triggered by mechanical stimuli, holds immense promise for diverse applications. However, most organic Mechanoluminescence materials suffer from short-lived luminescence, limiting their practical applications. Herein, we report isostructural doping as a valuable strategy to address this challenge. By strategically modifying the host matrices with specific functional groups and simultaneously engineering guest molecules with structurally analogous features for isostructural doping, we have successfully achieved diverse multicolor and high-efficiency persistent mechanoluminescence materials with ultralong lifetimes. The underlying persistent mechanoluminescence mechanism and the universality of the isostructural doping strategy are also clearly elucidated and verified. Moreover, stress sensing devices are fabricated to show their promising prospects in high-resolution optical storage, pressure-sensitive displays, and stress monitoring. This work may facilitate the development of highly efficient organic persistent mechanoluminescence materials, expanding the horizons of next-generation smart luminescent technologies.

Rapid room-temperature phosphorescence chiral recognition of natural amino acids

Chiral recognition of amino acids is very important in both chemical and life sciences. Although chiral recognition with luminescence has many advantages such as being inexpensive, it is usually slow and lacks generality as the recognition module relies on structural complementarity. Here, we show that one single molecular-solid sensor, L-phenylalanine derived benzamide, can manifest the structural difference between the natural, left-handed amino acid and its right-handed counterpart via the difference of room-temperature phosphorescence (RTP) irrespective of the specific chemical structure. To realize rapid and reliable sensing, the doped samples are obtained as nanocrystals from evaporation of the tetrahydrofuran solutions, which allows for efficient triplet-triplet energy transfer to the chiral analytes generated in situ from chiral amino acids. The results show that L-analytes induce strong RTP, whereas the unnatural D-analytes produce barely any afterglow. The method expands the scope of luminescence chiral sensing by lessening the requirement for specific molecular structures.

Facile dissolution of cellulose by superbase-derived ionic liquid using organic solvents as co-solvents at mild temperatures

Dissolving cellulose at low temperatures is a key step in its efficient utilization as a renewable resource to produce high-value-added platform chemicals and high-performance materials. Here, the potential of four aprotic organic solvents was investigated for use as co-solvents with a sustainable DBU-derived ionic liquid (SIL) for the low-temperature dissolution and regeneration of cellulose. Combined experiments, density functional theory calculations, and molecular dynamic simulations were performed. The type and amount of co-solvent were found to have a significant impact on the solubility of cellulose, the dissolution process, and the structure of regenerated cellulose. The addition of organic solvents can significantly reduce the cellulose dissolution temperature and increase the solubility. Among the solvents assessed, 40 wt% DMSO exhibited the most effective synergistic interaction with SIL, where the solubility of cellulose was 14.6 wt% at 75 °C. Subsequently, the effects of the different types and amounts of co-solvents on the microscopic morphology and chemical structure of regenerated cellulose were thoroughly explored. The results showed that different types of organic solvents had different effects on the microstructure of regenerated cellulose. The results may guide the manufacturing specifications of high-performance regenerated fiber materials.

Recent progress in ion-regulated organic room-temperature phosphorescence

Organic room-temperature phosphorescence (RTP) materials have attracted considerable attention for their extended afterglow at ambient conditions, eco-friendliness, and wide-ranging applications in bio-imaging, data storage, security inks, and emergency illumination. Significant advancements have been achieved in recent years in developing highly efficient RTP materials by manipulating the intermolecular interactions. In this perspective, we have summarized recent advances in ion-regulated organic RTP materials based on the roles and interactions of ions, including the ion-π interactions, electrostatic interactions, and coordinate interactions. Subsequently, the current challenges and prospects of utilizing ionic interactions for inducing and modulating the phosphorescent properties are presented. It is anticipated that this perspective will provide basic guidelines for fabricating novel ionic RTP materials and further extend their application potential.

ε-Polylysine organic ultra-long room-temperature phosphorescent materials based on phosphorescent molecule doping

Achieving long-lived room-temperature phosphorescence from pure organic amorphous polymers is attractive, and afterglow materials with colour-tunable and multiple-stimuli-responsive afterglow are particularly important, but only few materials with these characteristics have been reported so far. Herein, a facile and general method is reported to construct a series of ε-polylysine (ε-PL)-based afterglow materials with tunable colour (from blue to red) and long life. By doping guest molecules into ε-PL to obtain composite materials, the polymer matrix provides a rigid environment for luminescent groups, resulting in amorphous polymers with different RTPs. In this system, the materials even have impressive humidity-stimulated responses, and the phosphorescence emission exhibits excitation-dependent and time-dependent properties. The humidity-responsive afterglow is caused by the destruction of hydrogen bonds and quenching of triplet excitons. The time-dependent afterglow should stem from the formation of diversified RTP emissive species with comparable but different lifetimes. 9,10-diaminophene has Ex-De properties in the film doping state. With the change of excitation wavelength (254 nm to 365 nm), the emission wavelength shifts from 461 nm to 530 nm, accompanied by the change of emission colour from blue to green. In addition, the phosphorescence life of the film is the longest, up to 2504.7 ms, and the afterglow lasts up to 15 s, which is conducive to its applications in anti-counterfeiting and information encryption.

Insight into the Feasibility of Fatty Acyl Chlorides with 10-18 Carbons for the Ball-Milling Synthesis of Thermoplastic Cellulose Esters

Fatty acid cellulose esters (FACE) are common cellulose-based thermoplastics, and their thermoplasticity is determined by both the contents and the lengths of the side chains. Herein, various FACE were synthesized by the ball-milling esterification of cellulose and fatty acyl chlorides containing 10-18 carbons, and their structures and thermoplasticity were thoroughly studied. The results showed that FACE with high degrees of substitution (DS) and low melting flow temperatures (Tf) were achieved as the chain lengths of the fatty acyl chlorides were reduced. In particular, a cellulose decanoate with a DS of 1.85 and a Tf of 186 °C was achieved by feeding 3 mol of decanoyl chloride per mole anhydroglucose units of cellulose. However, cellulose stearate (DS = 1.53) synthesized by the same protocols cannot melt even at 250 °C. More interestingly, the fatty acyl chlorides with 10 and 12 carbons resulted in FACE with superior toughness (elongation at break up to 94.4%). In contrast, due to their potential crystallization of the fatty acyl groups with 14-18 carbons, the corresponding FACE showed higher tensile strength and Young's modulus than the others. This study provides some theoretical basis for the mechanochemical synthesis of thermoplastic FACE with designated properties.

Stable and ultralong room-temperature phosphorescent copolymers with excellent adhesion, resistance, and toughness

Developing stable room-temperature phosphorescence (RTP) emission without being affected by moisture and mechanical force remains a great challenge for purely organic systems, due to their triplet states sensitive to the infinitesimal motion of phosphors and the oxygen quencher. We report a kind of highly robust phosphorescent systems, by doping a rigid phosphor into a copolymer (polyvinyl butyral resin) matrix with a balance of mutually exclusive features, including a rigidly hydrophilic hydrogen bond network and elastically hydrophobic constituent. Impressively, these RTP polymeric films have superior adhesive ability on various surfaces and showed reversible photoactivated RTP with lifetimes up to 5.82 seconds, which can be used as in situ modulated anticounterfeit labels. They can maintain a bright afterglow for over 25.0 seconds under various practical conditions, such as storage in refrigerators, soaking in natural water for a month, or even being subjected to strong collisions and impacts. These findings provide deep insights for developing stable ultralong RTP materials with desirable comprehensive performance.

A flexible ligand and halogen engineering enable one phosphor-based full-color persistent luminescence in hybrid perovskitoids

Color-tunable room temperature phosphorescent (RTP) materials have raised wide interest due to their potential application in the fields of encryption and anti-counterfeiting. Herein, a series of CdX2-organic hybrid perovskitoids, (H-apim)CdX3 and (apim)CdX2 (denoted as CdX-apim1 and CdX-apim2, apim = 1-(3-aminopropyl)imidazole, X = Cl, Br), were synthesized using apim with both rigid and flexible groups as ligands, which exhibit naked-eye detectable RTP with different durations and colors (from cyan to red) by virtue of different halogen atoms, coordination modes and the coplanar configuration of flexible groups. Interestingly, CdCl-apim1 and CdX-apim2 both exhibit excitation wavelength-dependent RTP properties, which can be attributed to the multiple excitation of imidazole/apim, the diverse interactions with halogen atoms, and aggregated state of imidazoles. Structural analysis and theoretical calculations confirm that the aminopropyl groups in CdCl-apim1 do not participate in luminescence, while those in CdCl-apim2 are involved in luminescence including both metal/halogen to ligand charge transfer and twisted intramolecular charge transfer. Furthermore, we demonstrate that these perovskitoids can be applied in multi-step anti-counterfeiting, information encryption and smart ink fields. This work not only develops a new type of perovskitoid with full-color persistent luminescence, but also provides new insight into the effect of flexible ligands and halogen engineering on the wide-range modulation of RTP properties.

Intermolecular donor-acceptor stacking to suppress triplet exciton diffusion for long-persistent organic room-temperature phosphorescence

Controlling triplet states is crucial to improve the efficiency and lifetime of organic room temperature phosphorescence (ORTP). Although the intrinsic factors from intramolecular radiative and non-radiative decay have been intensively investigated, the extrinsic factors that affect triplet exciton quenching are rarely reported. Diffusion to the defect sites inside the crystal or at the crystal surface may bring about quenching of triplet exciton. Here, the phosphorescence lifetime is found to have a negative correlation with the triplet exciton diffusion coefficient based on the density functional theory (DFT)/time-dependent density functional theory (TD-DFT) calculations on a series of ORTP materials. For systems with a weak charge transfer (CT) characteristic, close π-π stacking will lead to strong triplet coupling and fast triplet exciton diffusion in most cases, which is detrimental to the phosphorescence lifetime. Notably, for intramolcular donor-acceptor (D-A) type systems with a CT characteristic, intermolecular D-A stacking results in ultra-small triplet coupling, thus contributing to slow triplet diffusion and long phosphorescence lifetime. These findings shed some light on molecular design toward high-efficiency long persistent ORTP.

Multi-Responsive Afterglows from Aqueous Processable Amorphous Polysaccharide Films

Polymer-based room-temperature phosphorescence (RTP) materials, especially polysaccharide-based RTP materials, earn sustained attention in the fields of anti-counterfeiting, data encryption, and optoelectronics owing to their green regeneration, flexibility, and transparency. However, those with both ultralong phosphorescence lifetime and excitation wavelength-dependent afterglow are rarely reported. Herein, a kind of amorphous RTP material with ultralong lifetime of up to 2.52 s is fabricated by covalently bonding sodium alginate (SA) with arylboronic acid in the aqueous phase. The resulting polymer film exhibits distinguished RTP performance with excitation-dependent emissions from cyan to green. Specifically, by co-doping with other fluorescent dyes, further regulation of the afterglow color from cyan to yellowish-green and near-white can be achieved through triplet-to-singlet Förster resonance energy transfer. In addition, the water-sensitive properties of hydrogen bonds endow the RTP property of SA-based materials with water/heat-responsive characteristics. On account of the color-tunable and stimuli-responsive afterglows, these smart materials are successfully applied in data encryption and anti-counterfeiting.

Recent developments in lignin-based fluorescent materials

Biomass-based fluorescent materials are an alternative to plastic-based materials for their multifunctional applications. Lignin, an inexpensive and easily available raw material, demonstrates outstanding environment-responsive properties such as pH, metal ions, dyes sensing, bioimaging and so on. To date, only a little work has been reported on the synthesis of lignin-based fluorescent materials. In this review report, synthetic approaches and light-responsive applications of lignin-based fluorescent carbon dots and other materials are summarized. The results reveal that lignin-based fluorescent carbon dots are prepared by hydrothermal method, exhibit small size <10 nm, reveal significant quantum yield, biocompatibility, non-toxicity, photostability and display substantial tunable emission and can be efficiently employed for sensing, bioimaging and energy storage applications. Finally, the forthcoming challenges, investigations, and options open for the chemical and/or physical modification of lignin into fluorescent materials for future applications are well-addressed. To our knowledge, this is the first comprehensive review report on lignin-based fluorescent materials and their light-responsive applications. In addition, this review will attract remarkable consideration and thrust for the researchers and biochemical technologists working with the preparation of lignin-based fluorescent materials for broad applications.

Synthesis of cyano and ionic dual-functional hypercrosslinked porous polymer for effective adsorption and detection of endocrine disrupting chemicals in milk matrix

Endocrine disrupting chemicals (EDCs) can interfere with the normal function of endocrine system, posing serious risk to human health. The monitoring of EDCs in foods is of great importance to ensure food security. Herein, a cyano and ionic dual-functionalized hypercrosslinked porous polymer (CN-iHCP) was designed and prepared for the first time through hyper-crosslink of 1-(4-cyanophenyl)imidazole and 1,4-bis(chloromethyl)benzene. The adsorption mechanism mainly involves electrostatic interaction, hydrogen bonding and π-π stacking interaction. A sensitive analytical method for simultaneous detection of the four phenolic EDCs was established by coupled CN-iHCP based solid-phase extraction with high performance liquid chromatography. Under optimal conditions, the target EDCs exhibited good linearity with coefficient r > 0.993 and high enrichment factors of 164-243. The detection limits (S/N = 3) of EDCs were 0.20-0.50 ng mL-1 for milk sample. The extraction recoveries for the spiked milk samples were in the range of 85.5%- 116.0%. This work not only highlights the CN-iHCP as a promising adsorbent to efficiently enrich EDCs and other pollutants, but also provides a new strategy for the functionalization of HCP for wide applications.

Micro assembly strategies for enhancing solid-state emission of cellulose nanocrystals and application in photoluminescent inks

Crystalline cellulose exhibits photoluminescent properties, making it ideal for solid-state emission through properly assembling crystal arrays. However, assembling in water or other polar solvents poses structural integrity issues. To address this, a micro-assembly method is proposed. Cellulose nanocrystals (CNCs) are organized within a sub-micrometer-sized ZIF-8 metal-organic framework and coated with TiO2. Notably, the assembly within ZIF-8 improves the CNCs' emission quantum yield to 37.8 %. The bonding between ZIF-8 and CNCs relies on electrostatic interactions and hydrogen bonds, which are sensitive to polar solvents. Yet, the sturdy coordination bonds between TiO2 and ZIF-8 enhance resistance. Solvent-resistance tests confirm that TiO2 prevents CNC assembly breakdown, resulting in only an 8.0 % drop in photoluminescent intensity in an alkaline solution after 24 h, compared to 33 % without the coating. For anti-counterfeiting purposes, TiO2@ZIF-8@CNC is combined with a polymer matrix, allowing information to be revealed under specific wavelengths using screen-printed labels.

Facile preparation strategy of novel B2O3-modified carbon dots with 1.99 s ultra-long Room-Temperature phosphorescence for multidimensional encryption

Facile synthesis of Ultralong room-temperature phosphorescence (URTP) with super stability and long-afterglow are of great significance, but hard to achieve. Herein, a brilliant gram-scale and solvent-free pyrolysis treatment strategy has been developed to prepare high-performance URTP carbon dots (CDs) by regulating different temperature (250-500 °C). The optimized CDs (CD-400) showed room-temperature phosphorescence 1.99 s and lasting over 22 s to naked eyes, which is superior to most of the reported URTP CDs. Owing to the stabilization effects of the modified B2O3 layer on the surface, the homogenous distribution of CD-400 with the narrow diameter of 1.44 nm was constructed, displaying a superb stability through hydrogen-bond network. In addition, the doping atoms (N, O) greatly enhanced the n-π* transitions and stabilized triplet excitons radiative transitions, facilitating the effective intersystem crossing (ISC) and the RTP emissions. More importantly, the B2O3-modified CDs were successfully applied in the multi-level information encryption (time-resolved RTP performance) and fingerprint identification (bifurcation, whorl and termination details).

Luminescent Mechanism and Anti-Counterfeiting Application of Hydrophilic, Undoped Room-Temperature Phosphorescent Silicon Nanocrystals

Silicon nanocrystals (SiNCs) have attracted extensive attention in many advanced applications due to silicon's high natural abundance, low toxicity, and impressive optical properties. However, these applications are mainly focused on fluorescent SiNCs, little attention is paid to SiNCs with room-temperature phosphorescence (RTP) and their relative applications, especially water-dispersed ones. Herein, this work presents water-dispersible RTP SiNCs (UA-SiNCs) and their optical applications. The UA-SiNCs with a uniform particle size of 2.8 nm are prepared by thermal hydrosilylation between hydrogen-terminated SiNCs (H-SiNCs) and 10-undecenoic acid (UA). Interestingly, the resultant UA-SiNCs can exhibit tunable long-lived RTP with an average lifetime of 0.85 s. The RTP feature of the UA-SiNCs is confirmed to the n-π* transitions of their surface C═O groups. Subsequently, new dual-modal emissive UA-SiNCs-based ink is fabricated by blending with sodium alginate (SA) as the binder. The customized anticounterfeiting labels are also prepared on cellulosic substrates by screen-printing technique. As expected, UA-SiNCs/SA ink exhibits excellent practicability in anticounterfeiting applications. These findings will trigger the rapid development of RTP SiNCs, envisioning enormous potential in future advanced applications such as high-level anti-counterfeiting, information encryption, and so forth.