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The turn-off fluorescent photoswitches for information encryption are constantly being developed. However, there are no reports about time-switchable (fluorescence lifetime-switchable) encryption to overcome the limitations of tunable encoding numbers in spectrally and temporally encoded libraries. Based on the double-exponential fitting of fluorescence lifetime, we propose, a fatigue-free and highly flexible switch between the amplitude-weighted average fluorescence lifetime (τm) and the intensity-weighted average fluorescence lifetime (τi), which will realize the supermultiplexed fluorescence lifetime switchable encryption. The potentially enormous library of different fluorescent lifetime combinations would facilitate the development of information security.

The utilization of solar energy to produce hydrogen from water is showing increased importance and desirability in the field of artificial photosynthesis to produce clean and sustainable fuels. In a typical three-component dye-sensitized semiconductor system for photocatalysis, the dye sensitizer plays an essential role of energy antenna for harvesting visible light and promoting the reduction reaction to generate hydrogen. In recent decades, a lot of attention has focused on metal-free organic sensitizers, which have the advantages of low cost, high molar extinction coefficient, good modifiability and, most importantly, ability to avoid the use of noble metal ions. This Review enumerates the design strategies, specific properties and photocatalytic performances of metal-free sensitizers in the past 30 years and concludes their evolution process. The advantages of different types of metal-free sensitizers are highlighted and the instructively enlightening experiences are systematic summarized.

A porous organic–inorganic hybrid material consisting of calix[4]arene dye C4BTP with pyridine as an acceptor and titanium dioxide, denoted as C4BTP–TiO2, has been prepared by a facile sol–gel method. The C4BTP–TiO2 materials show expandable photocatalytic activities for H2 evolution from water and CO2 reduction to CO when they are loaded with Pt nanoparticles or rhenium complex ReCl(bpy) (CO)3 (ReP) as co-catalysts, respectively. The optimized Pt/C4BTP–TiO2 (5.0 wt%) catalyst exhibits a high H2 production activity (11.99 mmol g−1 h−1 based on catalyst mass) and excellent recyclable durability (a turnover number of 12 981 within 50 h after 10 rounds) under visible-light (λ > 420 nm), presenting one of the best performances among all the heterogeneous photocatalytic systems based on metal-free sensitizers. As a contrast, the surface sensitized catalyst Pt/gel-TiO2/C4BTP only shows far lower activities than hybrid Pt/C4BTP–TiO2 under the same conditions. In addition, the optimized ReP/C4BTP–TiO2 (5.0 wt%) catalyst obtained by loading ReP exhibits a selective photoactivity for CO2 reduction to CO, giving a turnover number of 112 after 25 h of visible-light irradiation. The good photoactivity and durability of the as-prepared hybrid materials can be attributed to the firm Ti–N linkage and efficient electron transfer between metal-free dye C4BTP and the substrate TiO2, while the alkaline-stable Ti–N bond improves the stability of the photocatalysts under basic aqueous conditions. This study offers a good example for the design and preparation of stable organic/inorganic hybrid materials applied in solar energy-solar fuel conversion.

We present a phosphorescence lifetime imaging (PLIM) based oxygen sensor to monitor the local O2 level in conventional petri dish-based or microfluidic in vitro cell culture. The sensor film is fabricated by dissolving Pt(II) meso-tetrakis(pentafluorophenyl) porphine (PtTFPP) into a thermal curable poly(perfluoroether) (PFPE). The lifetime response of the sensor to O2 follows a linear Stern-Volmer relationship. Compared with PDMS as polymer matrix, the use of PFPE as the polymer matrix for PtTFPP mitigates both the dye induced cytotoxicity and the biomolecule adsorption problems of polydimethylsiloxane (PDMS), while maintaining cell compatibility. By using the sensor film with PFPE as the polymer matrix, the O2 tension during cell proliferation can be monitored in real time, and the resulting value can be used to calculate the per-cell O2 consumption. We tested the application of the sensor for monitoring the O2 tension during long term cell culture of HeLa cells and MDA-MB-231 cells, and calculated the O2 consumption per cell for MDA-MB-231 cells. Our study demonstrates that the PtTFPP/PFPE sensor can be employed as a general noninvasive lifetime imaging platform for studying the di-oxygen in in vitro tissue models at the cellular level as a function of space and time.

This study sought to use the undesirable concentration-dependent quenching to propose a simple multiplexed imaging analysis for histopathological identification of different stained tissues. To verify this point, the relationship between the fluorescence lifetime and eosin concentration was obtained. At low concentrations, the fluorescence lifetimes of eosin were independent of the concentration ( 100 μg ml−1). To further verify that multiplexed imaging of different tissues could be achieved only by eosin, we used fluorescence lifetime imaging microscopy (FLIM) to measure fluorescence lifetimes from hematoxylin and eosin (H&E) stained sections. Working directly on an average fluorescence lifetime (τm) histogram for lifetime-based separation easily achieved multiplexed imaging in situ. H&E stained erythrocytes, smooth muscles, collagen and artificial structures on a prepared microscopic slide could be identified without the need of alternating laser excitation, using hyperspectral systems and special staining or multi-labeled immunofluorescence. Using only eosin, different types of tissues could be distinguished by eosin concentration-dependent quenching. Hence, eosin fluorescence lifetimes potentially simplify multiplexed imaging and may have potential applications for pathological diagnosis.

Butyl acrylate grafted starch (St-g-BA) was made by the method of microwave-assisted synthesis, involving the combination of microwave irradiation and a chemical free radical initiator (H₂O 2- Fe 2+ ) to initiate the grafting reaction. The optimal conditions for the graft copolymerization with respect to reaction microwave power, exposure time and type of initiator were investigated. Under the optimal conditions, the percent grafting and grafting efficiency were 26.2% and 85.9%, respectively. The grafted starch was characterized by using Fourier transform infrared spectroscopy and scanning electron microscopy. The St-g-BA exhibited good tensile strength, elongation at break and abrasion resistance. Therefore, it is suggested this biomaterial could be used in various industrial applications such as textile sizing and food packaging.

New supramolecular structures were designed in this work using large-sized polyoxometalates (POMs) and crown-ether-based supramolecular cations selected as building blocks. Two novel supramolecular inorganic–organic hybrids [(3-F-4-MeAnis)([18]crown-6)]2[SMo12O40]•CH3CN (1) and [(4-IAnis)([18]crown-6)]3[PMo12O40]•4CH3CN (2) (3-F-4-MeAnis = 3-fluoro-4-methylanilinium and 4-IAnis = 4-iodoanilinium) were synthesized. Crystals 1 and 2 have been characterized by infrared spectroscopy (IR) and elemental analysis (EA). Based on X-ray diffraction analysis, Crystals 1 and 2 were constructed through noncovalent bonding interactions and belong to different space groups due to the difference of the building blocks used. Supramolecular cations formed due to strong N–H···O hydrogen bonding interactions between the six oxygen atoms of [18]crown-6 molecules and nitrogen atoms of anilinium derivatives. Crystal 1 has two different supramolecular cations with an anti-paralleled arrangement that forms a dimer through weak hydrogen bonding interactions between adjacent [18]crown-6 molecules. Crystal 2 has three independent supramolecular cations that fill large spaces between the [PMo12O40] polyoxoanions forming a rhombus-shape packing arrangement in the ac plane. Crystals 1 and 2 are unstable at room temperature.

With the rapid development of life sciences, there is an increasing demand for intravital fluorescence imaging of small animals. However, large dimensions and limited working distances of objective lenses in traditional fluorescence microscopes have limited their imaging applications mostly to superficial tissues. To overcome these disadvantages, researchers have developed the graded-index (GRIN) probes with small diameters for imaging internal organs of small animals in a minimally invasive fashion. However, dynamic imaging based on GRIN lens has not been studied extensively. Here, this paper presented a fluorescence endoscopic imaging system based on GRIN lenses using one-photon and two-photon excitation. GRIN lenses with 1.15 mm diameter and 7.65 mm length were used in the system. The images were acquired by a compact laser scanning imaging system with a resonant galvo-mirror system to scan the laser beam and a photomultiplier tube (PMT) to detect fluorescence signals. Experimental results showed that this system using two-photon excitation could implement dynamic fluorescence microendoscopic imaging and monitor the movement of blood flow beneath the skin in anesthetized mice while producing images with higher contrast and signal to noise ratio (SNR) than those using one photon excitation. It would be a useful tool for studying biological processes of small animals or plants in vivo.

Metallic glass film of Prsub60/subAlsub10/subNisub10/subCusub20/subis proposed to be used as a resist of phase-change lithography (PCL). PCL is a mask-less lithography technology by using laser-direct-writing to create the intended nanopatterns. Thermal distribution in the PrAlNiCu film after exposure is calculated by finite element method (FEM). Thin films are exposed by continuous-wave laser and selective etched by nitric-acid solution, and the patterns are discerned by optical and atomic force microscope. The etching rate of as-deposited PrAlNiCu is thus nearly five times of the crystalline film. These results indicate that PrAlNiCu metallic glass film is a promising resist for phase-change lithography.

The layer structures of the esophageal and oral tissues were investigated by using spectral imaging technology based on two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG). Because spectral imaging technology allows a simultaneous record of both the spectra and image, it is capable of identifying the layered structures of the epithelial tissues, including the keratinizing layer, epithelial cell layer and stromal layer in the molecular level, which are strongly correlated to tissue pathology. All this work indicates that this technique has the potential to provide more accurate and comprehensive information for the early pathological diagnosis of tissues with the stratified squamous epithelia.

A hydrophilic indocyanine green derivative (ICG-Der-02) was covalently doped into mesoporous silica-coated gold nanorods (AuNRs/mSiO2). The self-synthesized derivative offers one carboxyl functional group on a side chain, which enables ICG-Der-02 to be covalently linked to nanomaterials and reduces the probability of leakage/desorption of the dye. The detection of infrared luminescence around 1270 nm confirmed that 102 is efficiently generated by the nanocomposite (AuNRs/mSiO2-ICG-Der-02). Furthermore, a second layer of silica was coated onto the nanocomposite, which then was conjugated with the α(v) integrin-targeting cyclic peptide (RGD-4C). The cell tests showed that the resulting nanoconjugate (AuNRs/mSiO2-ICG-Der-02/RGD-4C) was able to bind preferentially to HT-1080 human fibrosarcoma cells. Due to the synergistic effect of the produced nanoconjugates, a dual-modality photothermal and photochemical therapy was successfully achieved by 808 nm irradiation. Compared to using photothermal or photochemical therapy alone, the dual-modality photothermal/photochemical therapeutic strategy proved to be more damaging to HT-1080 cells and enhanced the effectiveness of photodestruction. Our work presents a novel approach to the multimodal treatment of fibrosarcoma and shows promise for future use in cancer theranostics.

We explored the biocompatible gold nanoparticles (GNPs) with surface modified by chitosan in the applications of cell's response to X-ray irradiation. Substantial amounts of chitosan modified gold nanoparticles (CS-GNPs) were found to be internalized in cell cytoplasm revealed by transmission electron microscopy. Their in vitro cytotoxicity effects on MGC-803 cells and GES-1 cells were observed at 24, 48 and 72 h. The MTT results showed that CS-GNPs own excellent biocompatibility. The dose enhancement based on CS-GNPs induced the damage of MGC-803 cells under X-ray irradiation, monitored by clonogenic cell survival assay. We also investigated their effects on the survival rates of MGC-803 cells during irradiation for a dose up to 10 Gy using a radio-oncology linear accelerator (6 MeV). The survival fraction of cells incubated with different concentration of CS-GNPs was obviously reduced in comparison with that irradiation alone. The result also revealed an increase of cell inhibition with increasing the concentration of CS-GNPs. In conclusion, CS-GNPs can enhance the cell radiation therapeutic sensitivity, and have potential application in tumor irradiation therapy in near future.

Multifunctional nanoprobes are designed to own various functions such as tumor targeting, imaging and selective therapy, which offer great promise for the future of cancer prevention, diagnosis, imaging and treatment. Herein, silica was applied to replace cetyltrimethylammonium bromide (CTAB) molecules on the surface of gold nanorods (GNRs) by the classic Stober method, thus eliminating their cytotoxicity and improving their biocompatibility. Folic acid molecule was covalently anchored on the surface of GNRs with silane coupling agent. The resultant folic acid-conjugated silica-modified GNRs show highly selective targeting, enhanced radiation therapy (RT) and photo-thermal therapy (PTT) effects on MGC803 gastric cancer cells, and also exhibited strong X-ray attenuation for in vivo X-ray and computed tomography (CT) imaging. In conclusion, the as-prepared nanoprobe is a good candidate with excellent imaging and targeting ability for X-ray/CT imaging-guided targeting dual-mode enhanced RT and PTT.

Maskless phase-change lithographic technology is developed as a photoresist of phase-change materials. The controllable growth behavior of the crystallization region on an amorphous thin film of Ge 2 Sb 2 Te 5 (GST) irradiated by a laser beam is investigated; the GST thin film is deposited on a silicon substrate by the sputtering method. The results of a series of the experiments and the simulations all show that the width of a crystalline pattern is not only closely related to laser power and pulse duration, but also is apparently affected by the interactive area between the focused laser spot and thin film. The width maintains a nonlinear growth with the enhancement of the laser power until the thin film approaches melting, whereas it gradually reaches a constant value due to the local thermal equilibrium. This equilibrium makes the width irrelevant to the moving velocity with certain constraints when the laser works in continuous-wave mode. Within a defocus range of 15 μ m , the widths of the crystalline patterns are obtained in a broad range from 690 nm to 8.13 μ m under a 0.4-NA objective lens. By adjusting the defocus amount, some crystalline square patterns with expected widths in a wide range are fabricated, and the mean percentage error between the expected and fabricated widths is only 1.495%.

Indocyanine green-loaded mesoporous silica-coated gold nanorods (ICG-loaded Au@SiO2) were prepared for the dual capability of X-ray computed tomography (CT) and fluorescence imaging. X-ray CT scanning showed that ICG-loaded Au@SiO2 could provide significant contrast enhancement; Near-infrared fluorescence generated by the nanomaterial was present up to 12 h post intratumoral injection, thus enabling ICG-loaded Au@SiO2 to be used as a promising dual mode imaging contrast agent. Multiplexed images can be more easily obtained with this novel type of multimodal nanostructure compared with traditional contrast agents. The dual mode imaging probe has great potential for use in applications such as cancer targeting, molecular imaging in combination with radiotherapy, and photothermolysis.

A novel hydrothermal dephosphorylation route for the synthesis of ultrasmall nucleotide-coated superparamagnetic γ-Fe2O3 nanoparticles (∼5 nm) has been demonstrated. The synthesized γ-Fe2O3 nanoparticles show excellent thermal stability, water dispersion and biocompatibility, allowing possible applications for in vivo X-ray contrast agents.