Search

The development of effective multiphoton absorption (MPA) materials for near-infrared (NIR) light-driven photocatalysis holds great significance. In this study, we incorporated two multibranched cyclometallated iridium(III) modules with varying degrees of conjugation onto MPA-inert metal–organic frameworks (MOFs) to active MPA performance. Subsequently, the MOFs were further modified with Co(II) and hyaluronic acid (HA) to fabricate MINCHand MISCH, respectively. By introducing octupolar molecules and expanding the conjugation, MISCHexhibited a larger MPA cross section for efficient NIR light absorption and improved carrier transfer, leading to outstanding NIR light-driven multiphoton photocatalytic hydrogen production. Moreover, the HA modification enabled MISCHto achieve specific multiphoton photocatalytic hydrogen therapy for cancer cells. This study provides valuable insights into constructing highly active MPA materials for NIR light-driven photocatalysis, presenting a potential platform for hydrogen therapy in tumor treatment.

Consumer trust in fruit industry is partly depended on the labeling of its geographical origin. The accurate label is not only of great significance to consumers and retailers, but also for their brands shaping. This work evaluated the utility of Fourier transform near-infrared spectroscopy (FT-NIRS) in identifying the geographical origins of Chinese pears including Laiyang pear (Pyrus bretschneidericv. Laiyang), Dangshan pear (Pyrus bretschneideriRehd.cv.Dangshansuli), and Korla pear (Pyrus sinkiangensisT. T. Yu). FT-NIR spectra of 316 pears from three different geographical origins were obtained in the spectral range of 10,000–4000 cm−1. Preliminary investigation was first conducted based on principal component analysis (PCA) to confirm the similar spectral features of samples within one class, and the results showed that PC1and PC2were effective for the identification. Partial least square discriminant analysis (PLS-DA) models based on full spectra indicated that the optimal classification based on second-order derivative (Der2) preprocessed spectra achieved 100% correct classification rates (CCRs) in all datasets. After that, the multivariate selection strategies including two-dimensional correlation spectroscopy (2D-COS), competitive adaptive reweighted sampling (CARS) combined with successive projection algorithm (SPA), and uninformative variable elimination (UVE) combined with SPA were individually optimized for selecting the characteristic wavenumbers from full FT-NIR spectra. On the basis of simplified PLS-DA models establishment, the CCRs in calibration, cross-validation, and prediction sets of the selected CARS-SPA-PLS-DA model achieved 98.58%, 98.11%, and 98.08%, respectively. This research demonstrated that FT-NIRS combined with multivariate analysis can be successfully employed to identify the geographical origins of Chinese pears.

As a key factor in determining the optimal harvest period of Camellia oleiferafruit maturity is significant in increasing camellia oil yield. Due to the interference of environmental factors, capturing hyperspectral images of Camellia oleiferafruit on-site often suffers from a low spectral signal-to-noise ratio. In this study, the multi-head attention parallel residual block-cycle generative adversarial network (MAPRB-CycleGAN) model was used to reconstruct on-site spectral data of Camellia oleiferafruit. Meanwhile, the characteristics and quality of the reconstructed spectra were analyzed through subjective visual inspection of the curve effect and the principal component analysis (PCA) algorithm. Then, the modeling effect of the reconstructed on-site spectral data after being reconstructed by wavelet transform, PCA, and kernel principal component analysis was compared. After the conventional pretreatment method in chemometrics, the partial least squares discriminant analysis (PLS-DA) model established with the field original spectra of Camellia oleiferafruit achieved the highest classification accuracy of 93.82%. The maturity classification model of Camellia oleiferafruit established by the PLS-DA method using the reconstructed spectra from this paper achieved 99.54% accuracy, and the classification accuracy of this data set in multiple models was higher than that of other reconstructed data sets. The results indicate that hyperspectral imaging technique combined with MAPRB-CycleGAN can realize high-accuracy maturity classification of Camellia oleiferafruit, and the spectral reconstruction can be exploited as a preprocessing method for on-site spectral data collection, which provides important technical support for obtaining high-quality spectral data of Camellia oleiferafruit in field environments. The randomness and unpredictability of outdoor environmental factors lead to the diversity in data collection, and enhancing the robustness of generative models to cope with environmental influences is the most significant challenge in practical applications. It will also be the focal point of our future research.

The modern electromagnetic environment is becoming more and more complicated, and during detection, radar may face not only single jamming but also compound jamming signals that belong to different varieties, which is more challenging to recognize. Traditional methods are difficult to extract effective features from a variety of jamming signals and their compound signals. Here, a fractional Fourier transform (FRFT)-based multifeature fusion network has been proposed, which combines the multibranch fractional features of the jamming signals and improves the recognition performance. By combining the local and global features of the fractional domain of the jamming signals and adding the attention mechanism, the attention ability of the network to the notable features of images can be further improved. Meanwhile, to make use of the correlation and complementarity between multiple types of information, the time-frequency images of jamming signals are fused based on this network model to realize a more effective and comprehensive expression of features. Simulation results show that, compared with the existing four classical network models, this algorithm has better recognition performance and generalization ability. When the jamming-to-noise ratio is −3 dB, the recognition accuracy of this algorithm can reach more than 99%.

Micro-Doppler shift induced by precession is crucial for ballistic target recognition. However, traditional single radar has the limitation of single viewing angle, while radar network (RNW) faces complex data processing problem to extract the precession and structure parameters of the ballistic target. In this article, we establish a cone-shaped warhead model for ballistic missile (BM) and propose to estimate the precession and structure parameters of the BM target via micro-Doppler shift using a hybrid radar with traditional linear frequency modulation (LFM) signal and vortex electromagnetic (EM) wave signal. Via high-resolution range profile (HRRP) and the separation of radial and rotational Doppler shifts, the precession and structure parameters, such as height, base radius, and precession angle of the conical warhead, are estimated with high accuracy.

The uncontrollable distribution of antitumor agents remains a large obstacle for specific and efficient cancer theranostics; thus, efficient construction of tumor-specific systems is highly desirable. In this work, a general design of tumor stimulus-activatable pretheranostic agents was put forward via a series of structures-tunable triphenylamine derivatives (TPA-2T-FSQ, TPA-2T-BSZ, and TPA-2T-ML) with phenothiazine, benzothiazine, and thiomorpholine as identifying groups of hypochlorite (HClO), respectively. Notably, the sulfur atom in phenothiazine of TPA-2T-FSQwas more easily oxidized to sulfoxide groups by HClO, transforming into an electron acceptor to form an excellent push–pull electronic system, which was beneficial to a large redshift of absorbance and emission wavelengths. Based on this, TPA-2T-FSQresorted to a key of overexpressed HClO in the tumor to open “three locks”, viz, NIR fluorescence, photothermal, and photoacoustic signals for multimodal diagnostic and treatment of the tumor. This study provided an elegant design to adopt tumor stimulus-triggerable pretheranostic for improving theranostic accuracy and efficiency, which was regarded as a promising candidate for precision medicine.

Aiming to address the issue of deception jamming generated by digital radio frequency memory (DRFM), this study proposes a feature extraction algorithm based on variational mode decomposition (VMD) for deception jamming recognition and composite deception jamming recognition. First, models are constructed for the real echo (RE) and the deception jamming signals. Second, the VMD is conducted. Third, the features are extracted from the decomposed intrinsic mode function (IMF) and fed into the support vector machine (SVM) for classification and recognition. To mitigate the challenge of high dimensionality and reduce the complexity of the learning task, mode selection and interclass divisibility of feature selection methods are employed. The effectiveness of the proposed algorithm is verified through simulations. Prior to feature selection, a signal-to-noise ratio (SNR) of 0 dB results in a jamming recognition accuracy exceeding 95%. After feature selection, the recognition accuracy remains largely unchanged, while the recognition speed significantly improves. Compared with other methods in the same field, the recognition accuracy shows a notable improvement. Furthermore, the proposed method is evaluated for its effectiveness in recognizing composite deception jamming, and simulation results validate its performance.

Laser welding, as an important material processing technology, has been widely used in various fields of industry. In most industrial welding production and processing, high precision is required for welding parameters and fixed work pieces. However, in the process of laser welding, serious heat transfer effect will bring unpredictable welding deviations, and even a small deviation will lead to serious welding defects, which will affect the quality of the welded products. Traditional nondestructive testing methods have been widely used, but they have been proved to have some limitations. Existing laser welding defect detection schemes are mainly focused on the detection of postweld defects, which requires a large amount of data, and the real-time detection cannot be guaranteed. In this article, we propose a data acquisition system for collecting changes in physical characteristics during laser welding with the aids of multiple sensors. Based on the data originating from sensors’ system, an efficient laser welding defect detection model has been designed and investigated based on the multiscale convolutional neural network (MSCNN), bidirectional long short-term memory (BiLSTM), and attention mechanism (AM). The final proposed MSCNN-BiLSTM-AM fusion detection model can achieve 99.38% detection accuracy, which make the laser welding system more efficient and more suitable.

In this article, the influence of detecting targets’ radial acceleration (RA) and angular acceleration (AA) based on vortex electromagnetic (EM) waves in non-line-of-sight scenarios is investigated. Three typical kinds of cases about obstacles are studied in a simulation model. The spectrum spread of vortex electromagnetic wave with different topological charges under different non-line-of-sight scenarios is analyzed by simulation, and the errors of the targets’ accelerations are calculated. It is found that the detection errors are related to the purities of orbital angular momentum (OAM) modes in spectrum spread after passing through obstacles. The purity of the main mode of a single vortex electromagnetic wave cannot play an absolute role in the detection errors; the component and proportion with higher order modes in OAM spectra spreading have a greater impact on errors.

The design of metal-free nano-photosensitizers (nano-PSs) with high-order multi-photon activity for second near-infrared (NIR-II, 1000–1700 nm) light-induced photodynamic therapy (PDT) has always been an intractable challenge. In this study, a high-order multiphoton activity was successfully initiated in a facile process by the supramolecular assembly of bovine serum albumin (BSA) with a series of metal-free PSs (named as TPA-nCs (n= 2, 3, 4, 5, 6, and 7)), and an interesting structure-function relationship was revealed by the “odd-even” effect. Specifically, the prepared protein nano-assembly TPA-nCs@BSA initiated a zig-zag enhanced three-photon performance due to the huge differences in dipole moments between “odd” and “even” alkyl substituents of TPA-nCs. Among them, TPA-7C@BSA has the largest three-photon absorption cross section up to 4.81 × 10−81cm6s2photon−2, which could delicately execute effective NIR-II PDT towards H22-tumor by the reactive oxygen species generated upon the irradiation of laser (1250 nm). The “odd-even” regulation of alkyl chains provided a new idea for developing and improving multi-photon photosensitized metal-free materials for biomedical applications.

The fabrication of multifunctional photosensitizers (PSs) with abundant Type I/II ROS for efficient theranostics in the “therapeutic window” (700–900 nm) is an appealing yet significantly challenging task. We herein report a molecular tailoring strategy based on intramolecular two-photon Forster Resonance Energy Transfer (TP-FRET) to obtain a novel theranostic agent (Lyso-FRET), featuring the amplified advantage of energy donor (NH) and acceptor (COOH), because of the reuse of fluorescence energy with high efficiency of FRET (∼83%). Importantly, under the excitation by the near-infrared (840 nm) window, Lyso-FRETcan not only penetrate the deeper tissue with a higher resolution for fluorescence imaging due to the nonlinear optical (NLO) nature, but also generate more Type I (superoxide anion) and Type II (singlet oxygen) reactive oxygen species for hypoxic PDT. Moreover, Lyso-FRETtargeting lysosomes further promotes the effect of treatment. The experiments in vitroand in vivoalso verify that the developed TP-FRET PS is conducive to treating deep hypoxic tumors. This strategy provides new and significant insights into the design and fabrication of advanced multifunctional PSs.

The pursuit of mesoporous Fe-based nanoagents addresses the field of developing alternative Fe-bearing nanoagents for synergistic cancer therapy with the expectation that the use of an essential element may avoid the issues raised by the exogenous administration of other metal element-based nanoagents. Herein, we highlight the interface-engineered mesoporous FeB(mFeB) where the core mFeBis interfacially oxidized into an FeOOH nanosheet loaded with the chemotherapeutic drug doxorubicin (DOX) and further encapsuled within the double-sulfide-bonded SiO2outer layer, denoted as mFeB@DOX-ss-SiO2, which can realize programmed drug release for synergistic cancer theranostics. When only in a tumor microenvironment, the nanoagent can be activated to release DOX from the mFeBand FeOOH nanosheets as well as expose the easily oxidized mFeBto spontaneously transform to FeOOH nanosheets with Fenton activity to facilitate chemodynamic therapy (CDT). In addition, the high photothermal conversion efficiency of mFeB@DOX-ss-SiO2would promote CDT. Also, owing to the inherent nature of ferromagnetism and red fluorescence of DOX, mFeB@DOX-ss-SiO2can realize T2-weighted magnetic resonance imaging and fluorescence imaging. In vivo mouse model experiments demonstrate that mFeB@DOX-ss-SiO2with good biocompatibility realizing CDT/photothermal therapy/chemotherapy achieved complete tumor suppression. This study opens up a new way to explore theranostic nanoagents.

Various suborganelles are delimited by lipid bilayers, in which high spatial and temporal morphological changes are essential to many physiological and pathological processes of cells. However, almost all the amphiphilic fluorescent molecules reported until now are not available for in situ precise tracking of membrane dynamics in cell apoptosis. Here, the MO (coumarin pyridine derivatives) was devised by engineering lipophilic coumarin and cationic pyridine salt, which not only lastingly anchored onto the plasma membrane in dark due to appropriate amphipathicity and electrostatic interactions but also in situ reflected the membrane damage and heterogeneity with secretion of extracellular vesicles (EVs) under reactive oxygen species regulation and was investigated by two-photon fluorescence lifetime imaging microscopy. This work opens up a new avenue for the development of plasma membrane staining and EV-based medicines for the early diagnosis and treatment of disease.

Multiphoton materials are in special demand in the field of photodynamic therapy and multiphoton fluorescence imaging. However, rational design methodology for these brands of materials is still nascent. This is despite transition-metal complexes favoring optimized nonlinear-optical (NLO) activity and heavy-atom-effected phosphorescent emission. Here, three four-photon absorption (4PA) platinum(II) complexes (Pt1–Pt3) are achieved by the incorporation of varied functionalized C^N^C ligands with high yields. Pt1–Pt3exhibit triplet metal-to-ligand charge-transfer transitions at ∼460 nm, which are verified multiple times by transient absorption spectra, time-dependent density functional theory calculations, and low-temperature emission spectra. Further, Pt1–Pt3undergo 4PA. Notably, one of the complexes, Pt2, has maximum 4PA cross-sectional values of up to 15.2 × 10–82cm8s3photon–3under excitation of a 1600 nm femtosecond laser (near-IR II window). The 4PA cross sections vary when Pt2is binding to lecithin and when it displays its lysosome-specific targeting behavior. On the basis of the excellent 4PA property of Pt2, we believe that those 4PA platinum(II) complexes have great potential applications in cancer theranostics.

Cell viability is greatly affected by external stimulus eliciting correlated dynamical physiological processes for cells to choose survival or death. A few fluorescent probes have been designed to detect whether the cell is in survival state or apoptotic state, but monitoring the regulation process of the cell undergoing survival to death remains a long-standing challenge. Herein, we highlight the in situ monitor of mitochondria regulating the cell viability by the RNA-specific fluorescent photosensitizer L. At normal conditions, Lanchored mitochondria and interacted with mito-RNA to light up the mitochondria with red fluorescence. With external light stimulus, Lgenerated reactive oxide species (ROS) and cause damage to mitochondria, which activated mitochondrial autophagy to prevent death, during which the red fluorescence of Lwitnessed dynamical distribution in accordance with the evolution of vacuole structures containing damaged mitochondria into autophagosomes. However, with ROS continuously increasing, the mitochondrial apoptosis was eventually commenced and Lwith red fluorescent was gradually accumulated in the nucleoli, indicating the programmed cell death. This work demonstrated how the delicate balance between survival and death are regulated by mitochondria.

Photodynamic therapy (PDT) takes advantage of reactive oxygen species (ROS) to trigger the apoptosis for cancer therapy. Given that cell apoptosis is a form of programmed cell death involved with multiple suborganelles and cancer cells are more sensitive to ROS than normal cells, early confirmation of the apoptosis induced by ROS would effectively avoid overtreatment. Herein, we highlight an aggregation-induced emission (AIE)-based theranostic agent (TPA3) to in situ dynamically track mitophagy prior to late apoptosis. TPA3showed high specificity to autophagy vacuoles (AVs), of which appearance is the signature event of mitophagy during early apoptosis and delivered photocytotoxicity to cancer cells and skin cancer tumors in nude mice under irradiation of white light. Furthermore, in situ monitoring of the dynamical mitophagy process involved with mitochondria, AVs, and lysosomes was performed for the first time under confocal microscopy, providing a real-time self-monitoring system for assessing the curative effect prior to late apoptosis. This fluorescence imaging guided PDT witness great advances for applying in the clinical application.

Dynamic tracking of the spatiotemporal coordination among various organelles to in-depth understanding of the mechanism of autophagy have attracted considerable attention. However, the monitor of nucleoli participation in autophagy was somehow neglected. Herein, we report a RNA-targeted bioprobe (ADAP) with high selective permeability into nuclear pore complexes, which induced a two-photon (TP) fluorescence “off-on” response by groove combination with RNA, dynamically monitoring the autophagy process among multiorganelles (nucleoli, mitochondria, and mitochondria-containing lysosomes). This work provides a simple and convenient way to observe the dynamic behavior of multiorganelles during the autophagy process, which benefits the understanding of cellular metabolism.

Development of an activated ratiometric indicator that is specific to plasma membrane (PM) viscosity exhibits great application prospects in disease diagnosis and treatment but remains a great challenge. Herein, a photo-activated fluorescent probe (CQ-IC) was designed and prepared tactfully, which could analyze and real-time monitor the microenvironmental homeostasis of the PM based on a two-channel ratiometric imaging model. Interestingly, upon light irradiation, CQ-ICgenerates reactive oxygen species and thus increases the cellular viscosity, which increases two emission peaks at 480 and 610 nm. This work would propose a new strategy to sensor PM homeostasis and effectively guide the treatment of viscosity-related diseases among various physiological and pathological processes.

Currently, in situmonitoring of the adenosine triphosphate (ATP) level in lysosomes is critical to understand their involvement in various biological processes, but it remains difficult due to the interferences of limited targeting and low resolution of fluorescent probes. Herein, we report a classic Mn(II) probe (FX2-MnCl2) with near-infrared (NIR) nonlinear (NLO) properties, accompanied by three–four photon transition and fivefold fluorescence enhancement in the presence of ATP. FX2-MnCl2combines with ATP through dual recognition sites of diethoxy and manganese ions to reflect slightly fluorescence lifetime change. Through the synergy of multiphoton fluorescence imaging (MP-FI) and multiphoton fluorescence lifetime imaging microscopy (MP-FLIM), it is further demonstrated that FX2-MnCl2displays lysosome-specific targeting behavior, which can monitor lysosome-related ATP migration under NIR laser light. This work provides a novel multiphoton transformation fluorescence complex, which might be a potential candidate as a simple and straightforward biomarker of lysosome ATP in vitrofor clinical diagnosis.

The intrinsic stability of the acceptor is a crucial component of the photovoltaic device stability. In this study, we investigated the efficiency and stability of the nonfused-ring acceptors LC8 and BC8 under indoor light conditions. Interestingly, we found that devices based on BC8 with terminal side chains exhibited a higher indoor efficiency and stability. Through accelerated aging experiments, we discovered that the acceptors generate singlet oxygen under light exposure with BC8 demonstrating lower levels of ROS compared to LC8. We attribute this difference to the modulation of the acceptor aggregation orientation. Furthermore, the generated reactive oxygen species (ROS) further deteriorate the acceptor structure, and this phenomenon is also observed in high-efficiency acceptor structures, such as Y6. Our research reveals important mechanisms of acceptor photo-oxidation processes, providing a theoretical basis for enhancing the intrinsic stability of acceptors.

Unveiling the synergism among multiple organelles for fully exploring the mysteries of the cell has drawn more and more attention. Herein, we developed two two-photon fluorescent bioprobes (Lyso-TA and Mito-QA), of which the conformational change triggered an “off–on” fluorescent response. Lyso-TA can real-time monitor the fusion and movement of lysosomes as well as unveil the mitophagy process with the engagement of lysosomes. Mito-QA was transformed from Lyso-TA by one-step ambient temperature reaction, visualizing the dysfunctional mitochondria through a shift from mitochondria to nucleoli. With superior two-photon absorption cross section, good biocompatibility, and greater penetration depth, two small bioprobes were both applied in in vivobioimaging of brain tissues and zebrafish.

A novel efficient terpyridine-based colorimetric fluorescent compound, TPI, based on the Wittig reaction, was synthesized and impregnated on filter paper into test strips, which could be applied to naked-eye sensing of mercuric ions (Hg2+) in aqueous media through varied emission color from bright blue to yellow. TPI, with nitrogen from pyridine and oxygen from ether, had a high degree of water solubility and a strong coordination ability to Hg2+. Importantly, the test strips can be used to qualitatively trace amounts of hazardous Hg2+in various water samples and drinks.

Visualizing and dynamic tracking lipid droplets (LDs) are of great importance to biological research. Herein, two-photon absorption fluorescent small bioprobes based on lipophilic coumarin were developed, which exhibited high selectivity toward LDs in HeLa cells. Because of good biocompatibility and excellent photostability, the probes were applied to realize specific super-resolution visualization of the intracellular LDs in HeLa cells, offering us the quantitative results of the amount and diameters of LDs as well. Furthermore, the bioprobes were capable of monitoring the movements of the LDs in real time. We believe that bioprobes would provide new avenues to designing bioimaging and biological diagnosis.

It is currently challenged that nonlinear optical (NLO) properties in the near-infrared region (NIR) of metal complexes can be tunable with an assistant ligand. Herein, the linear and nonlinear photophysical properties of the novel C^N^C cyclometalated Pt(II) complexes with different substituents as auxiliary ligands are presented. The complexes displayed intense triplet metal/ligand-to-ligand charge-transfer (3MLCT/3LLCT) and intraligand 3π, π* emission at low-temperature. The excited-state characteristics are further confirmed over the TD-DFT calculations, transient absorption, and emission lifetimes. The Pt-3possesses a relatively high quantum yield (9.1%), a moderate triplet excited-state lifetime (5.32 μs), and a broad excited-state absorption from the visible to the near-IR region. Interestingly, it was found that Pt-3exhibited high 2PA cross section values (σ2up to 367 GM at 820 nm), as well as good optical limiting properties over a tunable femtosecond laser. The relationships between the structures and properties were systematically investigated on the basis of crystal structural information. Hence, cyclometalated Pt(II) complexes would become candidates for the application of the NIR NLO materials.

Antibacterial agents with two-photon absorption are expected to play a significant role in biomedical science. Herein, two novel organotin complexes, HLSn1and HLSn2, based on coumarin were designed, synthesized, and systematically investigated. It was found that these complexes possessed suitable two-photon-active cross sections in the near-infrared region. Moreover, complex HLSn1could efficiently inhibit the growth of Gram-negative Escherichia coliand Gram-positive Bacillus subtilis, especially the latter with a minimum inhibitory concentration (MIC; 90%) of 2 ± 0.14 μg mL–1, which is lower than that of Kanamycin (Kana, 8 ± 0.42 μg mL–1). Importantly, two-photon imaging and superresolution development of bacterial stain revealed that complex HLSn1can react with bacterial membranes, producing reactive oxygen species (ROS) and leading to cell death. These outcomes provide promising applications in the superresolution bacteria imaging, diagnostics, and treatment of bacterial infectious.

Novel triphenylamine (TPA)-based derivative L, which shows strong affinity for SiO32−and fluorometric detection of Cu2+over other anions or cations, has been synthesized by simple steps. The experimental results displayed that derivative Lhas a remarkable sensitivity towards SiO32−by producing separately dispersed and modified silica nanoparticles (NPs) with an average size of 377 nm in acetonitrile solution. Moreover, Lalso displayed obvious selectivity to Cu2+via29-fold fluorescence intensity enhancement with a blue shift of 33 nm due to the formation of a 2 : 1 complex at room temperature. In addition, the probe could map the distribution of intracellular SiO32−or Cu2+in live cells by fluorescence confocal microscopy.

A two-photon fluorescent probe (J1) that selectively stains intracellular nucleolar RNA was screened from three water-soluble terpyridine derivatives (J1–J3) with quaternary ammonium groups. The photophysical properties of J1–J3were systemically investigated both experimentally and theoretically, revealing that J1–J3possess large Stokes shifts and the two-photon absorption action cross sections range from 38 to 97 GM in the near-infrared region. This indicates that J1could specifically stain nucleoli by targeting the nucleolar rRNA from the recognition experiments in vitro, the two-photon imaging experiments, and the stimulated emission depletion in vivo. The mechanism of action in which J1binds to the nucleolar rRNA was researched via both experiments and molecular modeling. The high binding selectivity of J1to nucleolar RNA over cytosolic RNA made this probe a potential candidate to visualize rRNA probe in the living cells.

The purpose of this study was to compare the effects of different in vitromethods and different concentrations of polymers on the mucoadhesive properties of hydrogels. Mucoadhesive gels were prepared with four different polymers: Carbopol971P, Carbopol974P, hydroxypropylmethy cellulose (HPMC K100M) and sodium carboxymethyl cellulose (CMC-Na). The four concentrations of 1%, 1.5%, 2%, and 2.5% were tested. The above formulations were characterized in terms of mucoadhesion with a tensile test, the flowing liquid method and a rheological study. The four polymers all exhibited mucoadhesion according to each of the three methods, and the mucoadhesive properties of the hydrogels increased with increasing concentrations with the exception of Carbopol971P. The rank orders of the hydrogels were not inconsistent across the different testing methods even with the same measurement. Concentrations at the low and high level were found to influence the rank orders of mucoadhesion. The conflicting results confirmed that a stand-alone method or concentration should not be used to evaluate the mucoadhesion of hydrogels.

It is still a challenge that organotin(IV) carboxylate complexes with high-performance two-photon activity for cancer therapy. At present work, two novel organotin carboxylate complexes LSn1and LSn2, containing coumarin moiety, were rationally designed for two-photon fluorescent imaging and anticancer purpose. The complexes possessed large two-photon action cross-sections and high quantum yields. Living cells evaluation revealed that complexes LSn1and LSn2exhibited good biocompatibility and deep-tissue penetration over femtosecond laser with wavelength of 840 nm. Furthermore, the antitumor active and as well as possible mechanism of complexes LSn1and LSn2have been investigated systematically. The results indicated that complexes LSn1and LSn2could induce apoptotic cell death through a mitochondrial dysfunction and ROS elevation pathway. The present work provides a strategy for rationally designing organotin(IV) carboxylate complexes with two-photon activity and antitumor activity.

We have investigated the scattering properties of an individual core-shell nanoparticle using the Mie theory, which can be tuned to support both electric and magnetic modes simultaneously. In general, the suppression of forward scattering can be realized by the second Kerker condition. Here, a novel mechanism has to be adopted to explain zero-forward scattering, which originates from the complex interactions between dipolar and quadrupolar modes. However, for lossy and lossless core-shell spherical nanoparticles, zero-forward scattering can never be achieved because the real parts of Mie expansion coefficients are always positive. By adding proper gain in dielectric shell, zero-forward scattering can be found at certain incident wavelengths, which means that all electric and magnetic responses in Mie scattering can be counteracted totally in the forward direction. In addition, if the absolute values of dipolar and quadrupolar terms are in the same order of magnitude, the local scattering minimum and maximum can be produced away from the forward and backward directions due to the interacting effect between the dipolar and quadrupolar terms. Furthermore, by adding suitable gain in shell, super-forward scattering can also be realized at certain incident wavelengths. We also demonstrated that anomalously weak scattering or superscattering could be obtained for the core-shell nanoparticles with suitable gain in shell. In particular, for such a choice of suitable gain in shell, we can obtain zero-forward scattering and anomalously weak scattering at the same wavelength as well as super-forward scattering at another wavelength. These features may provide new opportunities for cloaking, plasmonic lasers, optical antennas, and so on.

Mitochondrial membrane potential (MMP) and sulfur dioxide (SO2) significantly affect the mitochondrial state. In this work, TC-2and TC-8were constructed through side-chain engineering, in which TC-2bearing the poorer hydrophobicity could localize on mitochondria better. Interestingly, short-wave emission was captured due to the sensitive response of TC-2to SO2(LOD = 13.8 nM). Meanwhile, the probe could bind with DNA, presenting enhanced long-wave emission. Encouragingly, TC-2could migrate from mitochondria to the nucleus when MMP was decreased, accompanied by the increase of fluorescence lifetime (9-fold). Hence, TC-2could be used for dual-channel monitoring of mitochondrial SO2and MMP, which showed a completely different pathway from the commercial MMP detectors JC-1/JC-10. The cellular experiments showed that MMP was gradually decreased due to reactive oxygen species-triggered oxidative stress, and the SO2level was up-regulated simultaneously. Overall, this work proposed a new method to investigate and diagnose the mitochondrial-related diseases.

The dicyanoisophorone derivatives show obvious AIE behaviors in our previous work. To study the bioimaging application of these chromophores with AIE/AIEE properties, the ester groups substituted for one cyan to form a new family based on isophorone (2a–2e). 2a–2dexhibit obvious AIE/AIEE phenomena, while 2eshows fluorescence quenching in the aggregate state. The morphology and size of aggregates with different water contents were investigated using SEM and DLS, indicating that a large number of smaller globular or quadrate nanoparticles with average diameters in the range 78.79–392.7 nm in mixed solutions are related to these AIE/AIEE or ACQ behaviors. We also made comparative analyses of their optical properties in different states. The crystal data of 2a–2dreveal that the multiple intra- and intermolecular interactions leads to the molecular conformation being more stable, increases the planarity of compounds, restricts the intramolecular motions, and promotes the formation of J-type aggregate, enabling chromophores 2a–2dto emit intensely in the solid state. In addition, the frontier molecular orbital energy and band gap calculated by density functional theory are quite consistent with the experimental results. Finally, these AIE/AIEE-active compounds could be used in bioimaging applications, which immensely provide a new strategy to the application of some AIE/AIEE systems.

Two novel terpyridine-based chromophores with D-A (D = donor, A = acceptor) structural model containing modified triphenylamine moiety (L1and L2) have been conveniently synthesized viaformylation and reduction in satisfactory yields, and fully characterized. The single crystals of them were obtained and determined by X-ray diffraction analysis. The relationships between structure and photophysical properties of the two chromophores were investigated both experimentally and theoretically. The measured maximum TPA cross-sections per molecular weight (δmax/MW) of the chromophores are 0.63 GM/(g mol) (L1) and 0.72 GM/(g mol) (L2), respectively, in DMF as a high polar solvent. The results indicate that the value of δmax/MW could be well tuned by the intramolecular charge transfer (ICT), which could be realized by introducing additional electron-donor/acceptor groups.

In this study, linear absorption, single-photon excited fluorescence, fluorescence quantum yields, fluorescence lifetime and two-photon excited fluorescence of a series of triphenylamine derivatives (L1, L2, L3 and L4) have been measured. L1and L3are D-p-A type dyes, while L2and L4are D-p-D-p-A type dyes (D = donor, A = acceptor). The investigated compounds consist of triphenylamine-bearing donor-substituted and/or systematically extended p-conjugated length, which are designed to gain insight into the effect of the ethoxyl unit and p-linkage length on the linear and nonlinear optical properties. The influence of solvent polarity on the photophysical properties was investigated. Employing time-dependent density functional theory (TD-DFT) calculations, the structure-property relationships are discussed.

A new series of D–π–A type two-photon absorption (2PA) dyes (1–4) based on imidazo[4,5-f]1,10-phenanthroline have been synthesized and their photophysical properties have been systematically investigated. These dyes showed obvious positive solvatochromic effects mainly due to intramolecular charge transfer (ICT). The two-photon absorption (2PA) cross-section values measured by two-photon excited fluorescence (TPEF) were determined to be 1232 GM and 4752 GM for dye 3and dye 4, while dyes 1and 2do not display 2PA activity. These results demonstrate that their 2PA cross section values (σ) increase with increasing donor/acceptor (D/A) strength of the corresponding molecule. The results also imply that the replacement of the tetrazol group with the aza-crown-ether group results in an opposite charge transfer direction, which has been verified by density functional theory (DFT) calculations. In addition, a two-photon fluorescence cell imaging experiment proved the suitability of dye 3for this potential application .

Abstract: Three bis-vinylpyridine compounds (4,4′-bis(2-vinylpyridine)biphenyl L 1, 4,4′-bis(3-vinylpyridine) biphenyl L 2, and 4,4′-bis (4-vinylpyridine)biphenyl L 3) were synthesized by one-step solid-state reactions at room temperature, giving nearly quantitative yields. The compounds obtained were fully characterized by IR, MS and NMR spectroscopies. The structures of L 2 and L 3 were determined by single crystal X-ray diffraction analysis. No noticeable solvatochromism was observed in either one-photon absorption or one-photon excited fluorescence spectra. All of the compounds have high fluorescence quantum yields and long fluorescence lifetime. The linear and nonlinear optical properties of the compounds were investigated both experimentally and theoretically. Interestingly, the position of the nitrogen atom from pyridine influences their two-photon absorption across-sections.

Abstract: Two new coordination polymers [ZnLI2]∞ (1) and [CdLI2]∞ (2) (L: 3,6-di-(1,2,4-triazole-1-yl)-N-hexylcarbazole) were synthesized and their crystal structures were determined by single-crystal X-ray diffraction techniques. Complexes are both constructed with the helical chains along the 2 1 screw axis. The coordination bond, C-H…I weak interactions and π-π interactions play significant roles in constructing their 3D or 2D frameworks. Two different DFT calculations are performed for the weak interactions between the helical chains of the three different coordination polymers ([ZnLI2]∞, [CdLI2]∞ and the reported [HgLI2]∞). The results reveal that weak interactions play important roles in these supramolecular systems of helical configuration, namely, the trend is the shorter H…I distance and π-π stacking distance, the stronger the intermolecular interactions. The photoluminescence of the complexes measured in the solid state at room temperature indicates that the emission intensity varies extensively, which can be rationalized by the heavy atom effect.

E310ethylphenothiazine3ylacrylic acid LCOOH was synthesized. LCOOH reacted with Ph3SnOH and nBu2SnO to afford Ph3SnO2CL 1 and {[nBu2SnO2CL]2O}22, respectively. The structures of all the compounds were solved by singlecrystal Xray diffraction. Compounds 1and 2present discrete and ladder frameworks, respectively. The onephoton absorption and excited fluorescence, and twophoton excited fluorescence spectra of all the compounds were systematically investigated. The results show that the two organostannoxanes exhibit much more enhanced twophoton absorption properties than LCOOH. TDDFT computational studies have been performed to elucidate the electronic structures of the ground state of LCOOH.© WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009

Intracellular lipid storage and regulation occur in lipid droplets, which are of great significance to the physiological activities of cells. Herein, a lipid droplet-specific fluorescence probe (lip-YB) with a high quantum yield (QYlip-YB= 73.28%), excellent photostability, and quickly polarity sensitivity was constructed successfully. Interestingly, lip-YBexhibited remarkable two-photon (TP) characteristics, which first realized real-time monitoring of the lipid droplet multidynamics process, diagnosing nonalcoholic fatty liver disease (NAFLD) and inflammation in living mice via TP fluorescence imaging. It is found that the as-prepared lip-YBprovides a new avenue to design lipid droplet-specific imaging probes, clarifies its roles and mechanisms in cell metabolism, and can timely intervene in lipid droplet-related diseases during various physiological and pathological processes.

Amperometric reaction detection of model peptides containing either a thiol or disulfide was successfully achieved with a novel coupled capillary liquid chromatography–dual microelectrode system. Detection is facilitated via dual platinum wire electrodes fabricated directly on a liquid chromatography capillary column. The detection strategy is based on the electrogeneration of bromine at the upstream working electrode followed by reduction of the bromine to bromide at the downstream working electrode. When bromine reacts with analyte eluting from the capillary column, the amount of bromine that reaches the downstream electrode decreases. As a result, the current at the downstream electrode will decrease in proportion to the amount of analyte eluting from the capillary column. Glutathione, glutathione disulfide, α-TGF and oxytocin were used to characterize the system and to determine system parameters. The feasibility of the determination of disulfide containing peptides is demonstrated with glutathione disulfide, α-TGF and oxytocin.

Considering the multiple biological barriers before the entry of photosensitizers (PSs) into cytoplasm, it is of paramount importance to track PSs to elucidate their behaviors and distributions to guide the photodynamic therapy (PDT). Also, the developed PSs suffer from strong oxygen dependency. However, reports on such ideal theranostic platforms are rare. Herein, we developed a theranostic platform (CMTP-2) based on the coumarin-based D-π-A system, which, for the first time, can reveal the holistic intracellular delivery pathway and near-infrared (NIR)-activated mitophagy to guide synergistic type-I PDT and photothermal therapy. The dynamic endo-lysosomal escape of CMTP-2was monitored, as well as its changeable distributions in endosomes, lysosomes, and mitochondria, demonstrating the preferential accumulation in mitochondria at the end. Upon NIR-I irradiation, CMTP-2generated toxic radicals and heat, triggering the execution of mitophagy and apoptosis. In vivo experiments on mice indicated that CMTP-2under 808 nm irradiation realized complete cancer ablation, showing great potential for advancements in synergistic phototherapy.

Strength degradation induced by geometrical discontinuities is a primary cause of structural failure for polymer bonded explosive (PBX). To restore structural integrity and extend service life, reinforcement of weakened PBX structures is urgently demanded. In the present work, carbon fiber reinforced polymer (CFRP) patches are employed to notched PBX simulant beams. By using digital image correlation (DIC) technique, the influences of CFRP patches on mechanical behavior of the beams under bending load are explored. Results show that the CFRP patches endows the beams with increased strength and stiffness. Due to the load-sharing and deformation-confining of the patches, stress concentration at the notch is relieved, and crack propagation in PBX simulant matrix is prevented. These discoveries may provide important enlightment for the reinforcement and repair of the weakened PBX structures, and in addition, provide basis to the potential application of CFRP patches in energetic materials.