Tunable Lifetime Research Articles

Time-domain stepwise encoding based on a stepped photon emission material.

We demonstrate tunable lifetimes (sub-milliseconds and seconds) at the same emission wavelength of a material, along with an abrupt intensity change between the two emission states. Based on this stepped photon emission material, a time-domain stepwise encoding method is developed and applied to point-of-care testing with an ultra-large quantitative detection range.

Sustainable afterglow materials from lignin inspired by wood phosphorescence

Sustainable organic afterglow room-temperature phosphorescence (RTP) is a particularly attractive phenomenon but remains difficult to achieve. Herein, inspired by the afterglow RTP of natural basswood, we prepare a series of sustainable afterglow RTP materials by confining lignin within a 3D poly(acrylic acid) network that mimics the wood matrix. The RTP emission of these materials could be finely tuned either by varying the drying temperature or the crosslinking density. Afterglow RTP emission could also be produced by embedding different types of lignin in a variety of 3D polymeric networks, thus demonstrating the generality of our strategy for preparing sustainable lignin-based RTP materials. As an illustration of potential applications, the lignin-based RTP materials are used to coat cotton fibers, which are then incorporated into luminescent textiles. • Room-temperature phosphorescence (RTP) of lignin in natural wood is reported • Sustainable afterglow RTP materials are prepared from lignin • As-prepared lignin-based afterglow RTP materials have a tunable lifetime Inspired by the afterglow room-temperature phosphorescence (RTP) of natural wood, Yuan et al. prepare sustainable afterglow RTP materials by confining lignin within a 3D molecular matrix, which paves a route for sustainable RTP materials.

Carbon dots confined in 3D polymer network: Producing robust room temperature phosphorescence with tunable lifetimes

Room temperature phosphorescence (RTP) is important in both organic electronics and encryption. Despite rapid advances, a universal approach to robust and tunable RTP materials based on amorphous polymers remains a formidable challenge. Here, we present a strategy that uses three-dimensional (3D) confinement of carbon dots in a polymer network to achieve ultra-long lifetime phosphorescence. The RTP of the as-obtained materials was not quenched in different polar organic solvents and the lifetime of the RTP was easily tuned by adjusting the amount of crosslinking or varying the drying temperature of the 3D molecular network. As a demonstration of potential application, as-obtained RTP materials were successfully used to prepare RTP fibres for flexible textiles. As well as bringing to light a fundamental principle for the construction of polymer materials with RTP, we have endowed traditional carbon dots and polymers with fresh features that will expand potential applications.

Synthesis and characterization of chemically fueled supramolecular materials driven by carbodiimide-based fuels.

Many supramolecular materials in biological systems are driven to a nonequilibrium state by the irreversible consumption of high-energy molecules such as ATP or GTP. As a result, they exhibit unique dynamic properties such as a tunable lifetime, adaptivity or the ability to self-heal. In contrast, synthetic counterparts that exist in or close to equilibrium are controlled by thermodynamic parameters and therefore lack these dynamic properties. To mimic biological materials more closely, synthetic self-assembling systems have been developed that are driven out of equilibrium by chemical reactions. This protocol describes the synthesis and characterization of such an assembly, which is driven by carbodiimide fuels. Depending on the amount of chemical fuel added to the material, its lifetime can be tuned. In the first step, the protocol details the synthesis and purification of the peptide-based precursors for the fuel-driven assemblies by solid-phase peptide synthesis. Then, we explain how to analyze the kinetic response of the precursors to a carbodiimide-based chemical fuel by HPLC and kinetic models. Finally, we detail how to study the emerging assembly's macro- and microscopic properties by time-lapse photography, UV-visible spectroscopy, shear rheology, confocal laser scanning microscopy and electron microscopy. The procedure is described using the example of a colloid-forming precursor Fmoc-E-OH and a fiber-forming precursor Fmoc-AAD-OH to emphasize the differences in characterization depending on the type of assembly. The characterization of a precursor's transient assembly can be done within 5 d. The synthesis and purification of a peptide precursor requires 2 d of work.

Bioresorbable Primary Battery Anodes Built on Core-Double-Shell Zinc Microparticle Networks.

Bioresorbable implantable electronics require power sources that are also bioresorbable with controllable electrical output and lifetime. In this paper, we report a bioresorbable zinc primary battery anode filament based on a zinc microparticle (MP) network coated with chitosan and Al2O3 double shells. When discharged in 0.9% NaCl saline, a Zn MP filament with a 0.17 × 2 mm2 cross-sectional area exhibited a stable voltage output of 0.55 V at a current of 0.01 mA. Covered by chitosan and Al2O3 double shells, the zinc MP filament exhibited a directional dissolution behavior with a tunable lifetime approximately linear to its length. A stable 200 h discharging time was achieved with a 15 mm Zn MP filament. The maximum output power was found to be 12 μW at 0.03 mA for one filament. The linearity relationship between the current output and the filament cross-sectional area suggested a facile strategy to raise the power output at constant discharging voltage. The filaments could also be connected in series and in parallel to boost its overall voltage and current output, demonstrating their excellent integration capability. This work presents a promising pathway toward bioresorbable transient batteries with controllable lifetime and power output, demonstrating a great potential for powering transient implantable biomedical devices.

Self-exothermic reaction driven large-scale synthesis of phosphorescent carbon nanodots

Phosphorescent carbon nanodots (CNDs) have various attractive properties and potential applications, but it remains a formidable challenge to achieve large-scale phosphorescent CNDs limited by current methods. Herein, a large-scale synthesis method for phosphorescent CNDs has been demonstrated via precursors’ self-exothermic reaction at room temperature. The as-prepared CNDs show fluorescence and phosphorescence property, which are comparable with that synthesized by solvothermal and microwave method. Experimental and computational studies indicate that exotic atom doped sp2 hybridized carbon core works as an emissive center, which facilities the intersystem crossing from singlet state to triplet state. The CNDs show phosphorescence with tunable lifetimes from 193 ms to 1.13 s at different temperatures. The demonstration of large-scale synthesis of phosphorescent CNDs at room temperature opens up a new window for room temperature fabrication phosphorescent CNDs.

Self-strengthening biphasic nanoparticle assemblies with intrinsic catch bonds

Protein–ligand complexes with catch bonds exhibit prolonged lifetimes when subject to tensile force, which is a desirable yet elusive attribute for man-made nanoparticle interfaces and assemblies. Most designs proposed so far rely on macromolecular linkers with complicated folds rather than particles exhibiting simple dynamic shapes. Here, we establish a scissor-type X-shaped particle design for achieving intrinsic catch bonding ability with tunable force-enhanced lifetimes under thermal excitations. Molecular dynamics simulations are carried out to illustrate equilibrium self-assembly and force-enhanced bond lifetime of dimers and fibers facilitated by secondary interactions that form under tensile force. The non-monotonic force dependence of the fiber breaking kinetics is well-estimated by an analytical model. Our design concepts for shape-changing particles illuminates a path towards novel nanoparticle or colloidal assemblies that have the passive ability to tune the strength of their interfaces with applied force, setting the stage for self-assembling materials with novel mechanical functions and rheological properties.

Carbazole&benzoindole-based purely organic phosphors: a comprehensive phosphorescence mechanism, tunable lifetime and an advanced encryption system

The same molecule synthesized from different carbazoles may show various properties, which originate from the trace isomer in purchased carbazole. By changing the content of isomers, the phosphorescence lifetime can be quantitatively adjusted.

Aggregation-induced room temperature phosphorescent carbonized polymer dots with wide-range tunable lifetimes for optical multiplexing

Four room-temperature phosphorescent carbonized polymer dots (CPDs) with wide-range tunable lifetimes from 730 ms to 2.26 s are prepared and applied for naked-eye visible multiplexing.

Host Differential Sensitization toward Color/Lifetime-Tuned Lanthanide Coordination Polymers for Optical Multiplexing.

Optical multiplexing based on luminescent materials with tunable color/lifetime has potential applications in information storage and security. However, the available tunable luminescent materials reported so far still suffer from several drawbacks of low efficiency or poor stability, thus restraining their further applications. Herein, we demonstrate a strategy to develop efficient and stable lanthanide coordination polymers (LCPs) with tunable luminescence as a new option for optical multiplexing. Their multicolor emission from green to red and naked-eye-sensitive green emission with tunable lifetime (from ca. 300 to ca. 600 μs) can be controlled by host differential sensitization and energy transfer between lanthanide ions. The quantum efficiencies of developed samples range from around 20 % to 46 % and the luminescence intensity/lifetime appear quite stable in polar solvents up to ten weeks. Furthermore, with the aid of inkjet printing and concepts of luminescence lifetime imaging and time-gated imaging, we illustrate their promising applications of information storage and security in spatial and temporal domains.

Host Differential Sensitization toward Color/Lifetime‐Tuned Lanthanide Coordination Polymers for Optical Multiplexing

AbstractOptical multiplexing based on luminescent materials with tunable color/lifetime has potential applications in information storage and security. However, the available tunable luminescent materials reported so far still suffer from several drawbacks of low efficiency or poor stability, thus restraining their further applications. Herein, we demonstrate a strategy to develop efficient and stable lanthanide coordination polymers (LCPs) with tunable luminescence as a new option for optical multiplexing. Their multicolor emission from green to red and naked‐eye‐sensitive green emission with tunable lifetime (from ca. 300 to ca. 600 μs) can be controlled by host differential sensitization and energy transfer between lanthanide ions. The quantum efficiencies of developed samples range from around 20 % to 46 % and the luminescence intensity/lifetime appear quite stable in polar solvents up to ten weeks. Furthermore, with the aid of inkjet printing and concepts of luminescence lifetime imaging and time‐gated imaging, we illustrate their promising applications of information storage and security in spatial and temporal domains.

Programmable ATP-Fueled DNA Coacervates by Transient Liquid-Liquid Phase Separation

Multivalency-driven liquid-liquid phase separation (LLPS) is essential in biomolecular condensates to facilitate spatiotemporal regulation of biological functions. Providing programmable model systems would help to better understand the LLPS processes in biology, and furnish new types of compartmentalized synthetic reaction crucibles that exploit biological principles. Herein, we demonstrate a concept for programming LLPS using transient multivalency between ATP-driven sequence-defined functionalized nucleic acid polymers (SfNAPs), which serve as simple models for membrane-less organelles. The ATP-driven SfNAPs are transiently formed by an enzymatic reaction network (ERN) of concurrent ATP-powered DNA ligation and DNA restriction. The lifetimes can be programmed by the ATP concentration, which manifests on the LLPS length scale in tunable lifetimes for the all-DNA coacervates. Critically, the prominent programmability of the DNA-based building blocks allows to encode distinct molecular recognitions for multiple multivalent systems, enabling sorted LLPS and thus multicomponent DNA coacervates, reminiscent of the diverse membraneless organelles in biological systems. The ATP-driven coacervates are capable for multivalent trapping of micron-scale colloids and biomolecules to generate functions as emphasized for rate enhancements in enzymatic cascades. This work supports ATP-driven multivalent coacervation as a valuable mechanism for dynamic multicomponent and function biomolecular condensate mimics and for autonomous materials design in general.

Multicompartment Tubular Micromotors Toward Enhanced Localized Active Delivery

A tubular micromotor with spatially resolved compartments is presented toward efficient site-specific cargo delivery, with a back-end zinc (Zn) propellant engine segment and an upfront cargo-loaded gelatin segment further protected by a pH-responsive cap. The multicompartment micromotors display strong gastric-powered propulsion with tunable lifetime depending on the Zn segment length. Such propulsion significantly enhances the motor distribution and retention in the gastric tissues, by pushing and impinging the front-end cargo segment onto the stomach wall. Once the micromotor penetrates the gastric mucosa (pH ≥ 6.0), its pH-responsive cap dissolves, promoting the autonomous localized cargo release. The fabrication process, physicochemical properties, and propulsion behavior are systematically tested and discussed. Using a mouse model, the multicompartment motors, loaded with a model cargo, demonstrate a homogeneous cargo distribution along with approximately four-fold enhanced retention in the gastric lining compared to monocompartment motors, while showing no apparent toxicity. Therapeutic payloads can also be loaded into the pH-responsive cap, in addition to the gelatin-based compartment, leading to concurrent delivery and sequential release of dual cargos toward combinatorial therapy. Overall, this multicompartment micromotor system provides unique features and advantages that will further advance the development of synthetic micromotors for active transport and localized delivery of biomedical cargos.

Biocatalytic Feedback-Controlled Non-Newtonian Fluids.

Non-Newtonian fluids are ubiquitous in daily life and industrial applications. Herein, we report an intelligent fluidic system integrating two distinct non-Newtonian rheological properties mediated by an autocatalytic enzyme reaction. Associative polyelectrolytes bearing a small amount of ionic and alkyl groups are engineered: by carefully balancing the charge density and the hydrophobic effect, the polymer solutions demonstrate a unique shear thickening property at low pH while shear thinning at high pH. The urea-urease clock reaction is utilized to program a feedback-induced pH change, leading to a strong upturn of the nonlinear viscoelastic properties. As long as the chemical fuel is supplied, two distinct non-Newtonian states can be achieved with a tunable lifetime span. As a proof of concept, we demonstrate how the physical energy-driven nonequilibrium properties can be manipulated by a chemical-fueled process.

Tunable lifetimes and efficiencies of room temperature phosphorescent liquids by modulating the length and number of alkyl chains.

Organic room temperature phosphorescence (RTP) liquid composites exhibit the potential to make innovative changes in large area flexible lighting applications, and it is extremely challenging to achieve high-efficiency RTP in pure organic solvent-free liquid systems. The excited state properties and inner lighting mechanisms of these composites are unclear; therefore, a theoretical perspective to design high efficiency RTP liquids with tunable lifetime is highly desired. Herein, we systematically investigate the photophysical properties of a series of long swallow-tailed bromonaphthalimide (BT unit) molecules by the newly proposed optimally tuned range-separated (RS) functional method, and a state-of-the-art RTP molecule with an absolute quantum yield (ΦRTP) of 57.1% and a lifetime (τ) of 160 ms in solvent-free liquid is obtained. Moreover, theoretical results show that the energy gap between the lowest singlet excited state (S1) and triplet excited state (T1) can be reduced and the non-radiative energy consumption process can be restricted by modulating the length and number of alkyl chains in organic RTP molecules. Thus, a wise molecular design strategy is proposed and five additional efficient RTP molecules with tunable lifetimes (43, 19, 136, 0.11 and 0.005 ms) and efficiencies (11.3%, 6.8%, 5.9%, 0.2% and 0.05%) are theoretically proposed. This study sheds light on the relationship among molecular structure, lifetime and efficiency, and can provide an important prototype to explore high-efficiency RTP by pure organic solvent-free liquid systems.

Transient supramolecular assembly of a functional perylene diimide controlled by a programmable pH cycle.

Self-regulating materials require embedded control systems. Active networks of enzymes fulfill this function in living organisms, and the development of chemical controls for synthetic systems is still in its infancy. While previous work has focused on enzymatic controls, small-molecule networks have unexplored potential. We describe a simple small-molecule network that is able to produce transient pH cycles with tunable lagtimes and lifetimes, based on coupling the acid-to-alkali methylene glycol-sulfite reaction to 1,3-propanesultone, a slow acid generator. Applied to transient pH-driven supramolecular self-assembly of a perylene diimide, our system matches the flexibility of in vitro enzymatic systems, including the ability to perform repeated cycles of assembly and disassembly.

Photoelectric Cardiac Pacing by Flexible and Degradable Amorphous Si Radial Junction Stimulators.

Implanted pacemakers are usually bulky and rigid electronics that are constraint by limited battery lifetimes, and need to be installed and repaired via surgeries that risk secondary infection and injury. In this work, a flexible self-powered photoelectric cardiac stimulator is demonstrated based on hydrogenated amorphous Si (a-Si:H) radial p-i-n junctions (RJs), constructed upon standing Si nanowires grown directly on aluminum thin foils. The flexible RJ stimulators, with an open-circuit voltage of 0.67 V and short-circuit current density of 12.7 mA cm-2 under standard AM1.5G illumination, can be conformally attached to the uneven tissue surface to pace heart-beating under modulated 650 nm laser illumination. In vivo pacing evaluations on porcine hearts show that the heart rate can be effectively controlled by the external photoelectric stimulations, to increase from the normal rate of 101-128 beating min-1 . Importantly, the a-Si:H RJ units are highly biofriendly and biodegradable, with tunable lifetimes in phosphate-buffered saline environment controlled by surface coating and passivation, catering to the needs of short term or lasting cardiac pacing applications. This implantable a-Si:H RJ photoelectric stimulation strategy has the potential to establish eventually a self-powered, biocompatible, and conformable cardiac pacing technology for clinical therapy.

Tunable Lifetimes of Intramolecular Charge-Separated States in Molecular Donor–Acceptor Dyads

We report ultrafast transient UV–vis absorption and electrochemical spectroscopies on the photoinduced charge separation dynamics in a recently synthesized family of metal-free donor–acceptor syste...

Lifetime-engineered NIR-II nanoparticles unlock multiplexed in vivo imaging.

Deep tissue imaging in the second near-infrared (NIR-II) window holds great promise for physiological studies and biomedical applications1-6. However, inhomogeneous signal attenuation in biological matter7,8 hampers the application of multiple-wavelength NIR-II probes to multiplexed imaging. Here, we present lanthanide-doped NIR-II nanoparticles with engineered luminescence lifetimes for in vivo quantitative imaging using time-domain multiplexing. To achieve this, we have devised a systematic approach based on controlled energy relay that creates a tunable lifetime range spanning three orders of magnitude with a single emission band. We consistently resolve selected lifetimes from the NIR-II nanoparticle probes at depths of up to 8 mm in biological tissues, where the signal-to-noise ratio derived from intensity measurements drops below 1.5. We demonstrate that robust lifetime coding is independent of tissue penetration depth, and we apply in vivo multiplexing to identify tumour subtypes in living mice. Our results correlate well with standard ex vivo immunohistochemistry assays, suggesting that luminescence lifetime imaging could be used as a minimally invasive approach for disease diagnosis.

Applications of Dissipative Supramolecular Materials with a Tunable Lifetime

AbstractSupramolecular materials are materials in which molecular building blocks are held together by non‐covalent interactions. These materials exist in equilibrium with their environment. In contrast, most biological materials exist out of equilibrium. They require constant dissipation of energy and consumption of nutrients to be sustained. As a result of their non‐equilibrium nature, biological materials have superior properties compared to their in‐equilibrium counterparts. These properties include spatial and temporal control over their presence, the ability to self‐heal and even the ability to self‐replicate. Inspired by biology, researchers have developed analogs of such dissipative supramolecular materials. This Focus Review introduces the crucial differences between in‐equilibrium and dissipative supramolecular materials. We focus on one unique property of the emerging materials: their tunable lifetime. With recent examples, we show the principles involved and how these materials can be applied in the future.