Ratiometric Fluorescence and Afterglow Lifetime Dual-Channel Nanoprobe for Simultaneous Imaging of HOCl and Temperature in Arthritis.

Arthritis is a joint disorder that potentially causes permanent joint damage and eventual disability without effective treatment. Clinical detection methods, including in vitro blood tests and anatomical imaging, still have limitations in achieving real-time in situ early detection of arthritis. In this work, a dual-channel luminescence nanoprobe (AGNPs-Cy7) is reported, which combines a cyanine dye and a photochemical reaction-based afterglow system for real-time in vivo imaging of arthritis. AGNPs-Cy7 simultaneously detect hypochlorous acid (HOCl) and temperature, two important indicators associated with the early development of arthritis, by monitoring the respective changes in independent ratiometric fluorescence and afterglow lifetime signals. The anti-interference properties of both the ratiometric fluorescence signal and afterglow lifetime signal enhance sensing accuracy compared to the single luminescence intensity. The developed probe successfully reveals the simultaneous increase in HOCl concentration and temperature in an arthritis mouse model.

Tunable Afterglow System via Controllable Photoenergy Storage and Release.

Afterglow luminescence has garnered significant attention due to its excellent optical properties. Currently, most afterglow phenomena are produced by persistent luminescence following cessation of the excitation light. However, it remains a challenge to control the afterglow luminescence process due to rapid photophysical or photochemical changes. Here, we develop a new strategy to control the afterglow luminescence process by introducing pyridones as singlet oxygen (1O2) storage reagents (OSRs), where 1O2 can be stored in covalent bonds at relatively low temperatures and released upon heating. The afterglow luminescence properties, including afterglow intensity, decay rate, and decay process, can be tuned flexibly by regulating temperature or OSR structures. Based on the controllable luminescence properties, we devise a new strategy for information security. We believe that such an excellent luminescent system also holds remarkable potential for applications in many other fields.

Ultra-long Near-infrared Repeatable Photochemical Afterglow Mediated by Reversible Storage of Singlet Oxygen for Information Encryption.

Photochemical afterglow systems have drawn considerable attention in recent years due to their regulable photophysical properties and charming application potential. However, conventional photochemical afterglow suffered from its unrepeatability due to the consumption of energy cache units as afterglow photons are emitted. Here we report a novel strategy to realize repeatable photochemical afterglow (RPA) through the reversible storage of 1 O2 by 2-pyridones. Near-infrared afterglow with a lifetime over 10 s is achieved, and its initial intensity shows no significant reduction over 50 excitation cycles. A detailed mechanism study was conducted and confirmed the RPA is realized through the singlet oxygen-sensitized fluorescence emission. Furthermore, the generality of this strategy is demonstrated and tunable afterglow lifetimes and colors are achieved by rational design. The developed RPA is further applied for attacker-misleading information encryption, presenting a repeatable-readout.

Thermal Stability of Polycaprolactone Grafted Densely with Maleic Anhydride Analysed Using the Coats-Redfern Equation.

The plastic waste problem has recently attracted unprecedented attention globally. To reduce the adverse eff ects on environments, biodegradable polymers have been studied to solve the problems. Poly(ε-caprolactone) (PCL) is one of the common biodegradable plastics used on its own or blended with natural polymers because of its excellent properties after blending. However, PCL and natural polymers are difficult to blend due to the polymers' properties. Grafted polymerization of maleic anhydride and dibenzoyl peroxide (DBPO) with PCL is one of the improvements used for blending immiscible polymers. In this study, we first focused on the effects of three factors (stirring time, maleic anhydride (MA) amount and benzoyl peroxide amount) on the grafting ratio with a maximum value of 4.16% when applying 3.000 g MA and 1.120 g DBPO to 3.375 g PCL with a stirring time of 18 h. After that, the grafting condition was studied based on the kinetic thermal decomposition and activation energy by the Coats-Redfern method. The optimal fitting model was confirmed by the determination coefficient of nearly 1 to explain the contracting volume mechanism of synthesized PCL-g-MA. Consequently, grafted MA hydrophilically augmented PCL as the reduced contact angle of water suggests, facilitating the creation of a plastic-biomaterial composite.

Enhanced Blue Afterglow through Molecular Fusion for Bio-applications.

Afterglow materials have drawn considerable attention due to their attractive luminescent properties. However, their low-efficiency luminescence in aqueous environment limits their applications in life sciences. Here, we developed a molecular fusion strategy to improve the afterglow efficiency of photochemical afterglow materials. By fusing a cache unit with an emitter, we obtained a blue afterglow system with a quantum yield up to 2.59 %. This is 162 times higher than that achieved with the traditional physical mixing system and more than an order of magnitude larger than that of the covalent coupling system. High-efficiency afterglow nanoparticles were obtained and utilized for bio-imaging with a high signal-to-noise ratio (SNR) of 131, and for the lateral flow immunoassay (LFIA) of ß-hCG with a low limit of detection (LOD) of 0.34 mIU mL-1 . This paves a new way for the construction of high-efficiency afterglow materials and expands the number of luminescence reporter candidates for disease diagnosis and bio-imaging.

Wide-Range Time-Dependent Color-Tunable Light-Response Afterglow Materials via Absorption Compensation for Advanced Information Encryption.

Stimuli-responsive luminescent materials with time-dependent color are highly desirable in optical information encryption. In this study, multiple time-dependent color processes are achieved by light-responsive afterglow materials through the strategy of absorption compensation. Based on the single-emission band of light-responsive afterglow materials, the color of samples could show a time-dependent change from colored to colorless over several seconds. The strategy possesses high flexibility such that the stimulus light and emission color of light-responsive afterglow materials can be adjusted conveniently to adapt to various scenes. It is also beneficial to expand the capacity and complexity of information encryption. A three-color, time-resolved anticounterfeiting, and data encryption mode is demonstrated. This facile absorption compensation method based on light-response afterglow materials may promote the development of advanced dynamic information encryption.

Visualization of Acute Inflammation through a Macrophage-Camouflaged Afterglow Nanocomplex.

Acute inflammation is a basic innate, immediate, and stereotyped immune response to injury, which is characterized by rapid recruitment of immune cells to the vasculature and extravasation into the damaged parenchyma. Visualization of acute inflammation plays an important role in monitoring the disease course and understanding pathogenesis, which lacks specific targeted and observing tools in vivo. Here, we report a Trojan horse strategy of a macrophage-camouflaged afterglow nanocomplex (UCANPs@RAW) to specifically visualize acute inflammation. Due to the advantages of optical antibackground interference elimination, as well as particular immune homing and long-term tracking capacity, UCANPs@RAW demonstrates an excellent acute inflammatory recognition ability. In an arthritis model, previously intravenously injected UCANPs@RAW could directionally migrate from the liver to the inflammation site as soon as 3 h after the model was induced, which could be continuously lighted for at least 36 h with the highest imaging signal-to-background ratio (SBR) as 382 at the time point of 9 h. Additionally, UCANPs@RAW is observed to penetrate the blood-brain barrier and image the deep brain inflamed region covered by the thick skull in an acute brain inflammation model with an SBRmax of 258, which is based on the strong recruiting ability of macrophages to immune response. In view of this smart nanocomplex, our strategy holds great potential for inflammatory detection and treatments.

Afterglow Implant for Arterial Embolization and Intraoperative Imaging.

Transcatheter arterial embolization (TAE) is wildly used in clinical treatments. However, the online monitoring of the thrombosis formation is limited due to the challenges of the direct visualization of embolic agents and the real-time monitoring of dynamic blood flow. Thus, we developed a photochemical afterglow implant with strong afterglow intensity and a long lifetime for embolization and imaging. The liquid pre-implant injected into the abdominal aorta of mice was rapidly transformed into a hydrogel in situ to embolize the blood vessel. The vascular embolism position can be observed by the enhanced afterglow of the fixed implant, and the long lifetime of afterglow can also be used to monitor the effect of embolization. This provides an excellent candidate in bio-imaging to avoid the autofluorescence interference from continuous light excitation. The study suggests the potential usefulness of the implant as an embolic agent in TAE and artery imaging during a surgical procedure.

Afterglow Amplification for Fast and Sensitive Detection of Porphyria in Whole Blood.

Porphyria is a group of genetic photodermatoses that cause too much porphyrin to accumulate in the blood, skin, and liver, resulting in skin photosensitivity and damage, liver disease, or potential liver failure. Conventional detection methods include high-performance liquid chromatography and fluorescence spectrometry. However, these methods usually require complicated pretreatment and time-consuming processes. Therefore, efficient and fast detection of porphyria is urgently needed. Herein, we develop a molecular afterglow reporter-based sensing scheme for the detection of porphyrins in whole blood. The afterglow reporter can respond to the production of singlet oxygen (1O2) of porphyrins after light excitation, and the detection signals can be amplified through adjusting the amount of singlet oxygen and afterglow reporter molecules. Moreover, without the use of a real-time excitation source, afterglow signals can avoid the scattering and autofluorescence interference in biological samples, thereby reducing background noise. More importantly, we prove the applicability of the afterglow reporter in the quantitative detection of porphyrins in whole blood and demonstrate its great clinical potential.

Light-Responsive Luminescent Materials for Information Encryption Against Burst Force Attack.

Optical encryption with easy operation, multichannel and high security has been one of the most significant technologies for information security. Stimuli-responsive luminescent materials have emerged as an ideal candidate for optical encryption, owing to its smart responsive property and high security. Herein, a type of light-responsive multicolor luminescent materials for high-security information encryption, which are fabricated by combining sensitizer, consumption unit, and emitter is developed. Different types of sensitizers to achieve different stimulus light responses, and multicolor light-responsive luminescent can be obtained by varying the composition of perovskite nanocrystals emitter can be selected. Both stimulus light and emission color can be used as distinguishable encoding dimensions, which enable multiplexed encoding with high capacity and complexity. Importantly, the controllable consumption can be manipulated by varying the concentration of consumption unit, so the programmed information encoded in different channels can be selectively read and erased simultaneously by varying stimulus light. The method makes the encryption information highly resistive to brute force trial-and-error attacks, which achieves high security level of information protection.

First cycloruthenation of 2-alkenylpyridines: synthesis, characterization and properties.

Several cyclometalated ruthenium complexes 1-5 with 2-alkenylpyridines as C,N-chelating ligands were synthesized and then characterized by NMR, MS, IR and UV-Vis spectra. According to the single crystal of complex 2, it is evident that carbon from vinyl group is successfully bonded to Ru(ii) center. Moreover, the Ru-N bond trans to the Ru-C bond is elongated (2.127(5) Å), which is consistent with the strong trans effect of the carbon atom compared to that of the nitrogen atom. With different electron-donating groups linked to vinyl, these complexes exhibited regular changes in MLCT absorption bands, which were identified by UV-Vis and CV spectra in combination with DFT and TD-DFT. Interestingly, protonated intermediate species of these complexes in acidic solutions were tracked by the absorption changes and MS spectra, which displayed a possible protonation process of these complexes with the cleavage of Ru-C σ bonds.

Lifetime-based nanothermometry in vivo with ultra-long-lived luminescence.

We developed a luminescence lifetime-based nanothermometer with a single-exponential luminescence decay in the ∼s time scope via a photochemical reaction. The luminescence lifetime imaging in vivo can be performed on an EMCCD and consumer-grade camera, which significantly reduces the technical threshold of luminescence lifetime imaging.

Near-Infrared Upconversion Luminescence and Bioimaging In Vivo Based on Quantum Dots.

Recently, upconversion luminescence (UCL) has been widely applied in bioimaging due to its low autofluorescence and high contrast. However, a relatively high power density is still needed in conventional UCL bioimaging. In the present study, an ultralow power density light, as low as 0.06 mW cm-2, is applied as an excitation source for UCL bioimaging with PbS/CdS/ZnS quantum dots (UCL-QDs) as probes. The speculated UCL mechanism is a phonon-assisted single-photon process, and the relative quantum yield is up to 4.6%. As determined by continuous irradiation with a 980 nm laser, the UCL-QDs show excellent photostability. Furthermore, UCL-QDs-based probe is applied in tumor, blood vessel, and lymph node bioimaging excited with an eye-safe low-power light-emitting diode light in a nude mouse with few heat effects.

Benzo[e]indolium derivatives in aqueous solutions: Reaction with bisulfite and successive interaction with Cu2+ and Hg2.

A new benzo[e]indolium derivative 1 including pyridyl and thienyl groups was synthesized and characterized, which failed to response to Hg2+ or Cu2+ in aqueous system. However, it is interesting that when it reacted with bisulfite in HEPES buffer, the in situ generated ensemble as 1-SO3H displayed dramatic absorption and fluorescence changes after adding Cu2+ or Hg2+, which were contrary to the changes of 1 upon the addition of bisulfite ions. By contrast, the other two derivatives 2 and 3 showed the almost similar trends of spectral changes, which were short of ligating atoms N or S. The further investigation of 1HNMR spectra changes of 1 showed that C-SO3H bond may be interrupted because the good binding capacity of Hg2+ and Cu2+ with O of C-SO3H weaken the binding force of C-SO3H, which resulted in the recovery of ethylene with benzo[e]indolium block. The DFT calculations results further confirmed it.

Achieving efficient photodynamic therapy under both normoxia and hypoxia using cyclometalated Ru(ii) photosensitizer through type I photochemical process.

Photodynamic therapy (PDT) through the generation of singlet oxygen utilizing photosensitizers (PSs) is significantly limited under hypoxic conditions in solid tumors. So it is meaningful to develop effective PSs which can maintain excellent therapeutic effects under hypoxia. Here we reported a coumarin-modified cyclometalated Ru(ii) photosensitizer (Ru2), which exhibits lower oxidation potential and stronger absorption in the visible region than the coumarin-free counterpart. The evaluation of the PDT effect was performed under both normoxia and hypoxia. The results showed that Ru2 has a better therapeutic effect than the coumarin-free counterpart in in vitro experiments. Especially under hypoxia, Ru2 still retained an excellent PDT effect, which can be attributed to the direct charge transfer between the excited PS and an adjacent substrate through a type I photochemical process, forming highly-oxidative hydroxyl radicals to damage tumor cells. The anti-tumor activity of Ru2 was further proven to be effective in tumor-bearing mice, and tumor growth was inhibited remarkably under PDT treatment.

Cycloruthenated complexes: pH-dependent reversible cyclometallation and reactions with nitrite at octahedral ruthenium centers.

The pH-dependent reversible cyclometallation and reactions with nitrite in a near-aqueous system of a related set of cyclometallated ruthenium(ii) bipyridyl complexes were investigated in detail. These complexes are [Ru(ppy)(bpy)2]PF6 (, bpy = 2,2'-bipyridine, Hppy = 2-phenylpyridine), [Ru(thpy)(bpy)2]PF6 (, Hthpy = 2-(2-thienyl)pyridine), and [Ru(dfppy)(bpy)2]PF6 (, Hdfppy = 2-(2,4-difluorophenyl)pyridine). As expected, reversible UV-Vis spectra of these three complexes in near-aqueous solutions can be achieved by treating with acid or base, which indicates a pH-dependent reversible cyclometallation. However, the addition of nitrite to acidic solutions of these complexes disturbed the reversible pH-dependent processes. Unexpected ruthenium complexes in the aforementioned system were then isolated and characterized using FT-IR, MS, (1)H NMR, and UV-Vis spectra, indicating that two reaction modes occurred at the ruthenium(ii) centers: (1) the insertion of NO into the ruthenium-aryl bond to form a ruthenium C-nitroso complex; and (2) the coordination of NO with the entire dissociation of one bipyridine to form a {Ru-NO}(6) complex, which is the first example involving the cleavage of Ru-N(∧)N bonds in ruthenium bipyridyl complexes.

A mercuric ensemble based on a cycloruthenated complex as a visual probe for iodide in aqueous solution.

A new water-soluble cycloruthenated complex Ru(bthiq)(dcbpy)2(+) (1, Hbthiq=1-(2-benzo[b]thiophenyl)isoquinoline, dcbpy=4,4'-dicarboxylate-2,2'-bipyridine) was designed and synthesized to form its mercuric ensemble (1-Hg(2+)) to achieve visual detection of iodide anions. The binding constant of 1-Hg(2+) is calculated to be 2.40×10(4)M(-1), which is lower than that of HgI2. Therefore, the addition of I(-) to the aqueous solution of 1-Hg(2+)lead to significant color changes from yellow to deep-red by the release of 1. The results showed that iodide anions could be easily detected by the naked eyes. The detection limit of iodide anion is calculated as 0.77µM. In addition, an easily-prepared test strip of 1-Hg(2+) was obtained successfully to detect iodide anions.

Hydrophilic Indolium Cycloruthenated Complex System for Visual Detection of Bisulfite with a Large Red Shift in Absorption.

Bisulfite, as an important additive in foodstuffs, is one of the most widely distributed environmental pollutants. The excessive intake of bisulfite may cause asthmatic attacks and allergic reactions. Therefore, the determination and visual detection of bisulfite are very important. Herein, a newly designed hydrophilic indolium cycloruthenated complex, [Ru(mepbi)(bpy)2](+) [1; bpy = 2,2'-bipyridine and Hmepbi = 3,3-dimethyl-1-ethyl-2-[4-(pyridin-2-yl)styryl]benzo[e]indolium iodide (3)], was successfully synthesized and used as a bisulfite probe. The bisulfite underwent a 1,4-addition reaction with complex 1 in PBS buffer (10 mM, pH 7.40), resulting in a dramatic change in absorption spectra with a red shift of over 100 nm and a remarkable change in solution color from yellow to pink. It is worth noting that this obvious bathochromic shift is rarely observed in the detection of bisulfite through an addition reaction. The detection limit was calculated to be as low as 0.12 µM by UV-vis absorption spectroscopy. Moreover, complex 1 was also used to detect bisulfite in sugar samples (granulated and crystal sugar) with good recovery.