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Aggregation induced emission (AIE) dots have gained broad attention in fluorescence bioimaging and biosensors in virtue of their distinctive optical properties of splendid biocompatibility, high brightness and good photostability. However, the application of AIE dots in sensing and imaging of enzymes in cells remains at an early stage and needs to be further explored. In this report, we proposed a novel AIE-dot-based nanoprobe for hyaluronidase (HAase) detection using a simple electrostatic self-assembly of AIE dots with gold nanoparticles functionalized using hyaluronic acid (HA-AuNPs), named HA-AuNPs@AIEDs. The fluorescence of AIE dots can be obviously quenched by HA-AuNPs via fluorescence resonance energy transfer (FRET). HAase could degrade HA into small pieces and thus induce disassembly of AuNPs and AIEDs, accompanied by fluorescence recovery of AIEDs. The as-prepared nanoprobe exhibited high sensitivity, excellent selectivity, wide response range and desirable anti-interference for quantitative sensing of HAase in vitro. The detection limit was down to 0.0072 U mL−1. Moreover, the nanoprobe displayed good biocompatibility and excellent photostability, and thus offered a practicable “turn-on” strategy for specific, high-contrast fluorescence imaging of HAase in live tumor cells. The AIE-based nanoprobe may provide a novel universal platform for recognition and imaging of HAase in tumors, and may be beneficial for related biological research.

Exploiting an intelligent fluorescent probe, which can precisely target to the lysosome of hepatoma cells and enable accurate molecular imaging, is a key challenge in hepatoma diagnoses. Herein, a single-dye-based polymer nanoprobe (named SPN) with dual-targeting and self-calibrating ratiometric characteristics is rationally fabricated via a simple self-assembly strategy for accurate hypochlorous acid (HClO) imaging in the lysosome of HepG2 cells. Of note, the covalent incorporation of self-calibrating ratiometric fluorophore (pyrene derivatives) into the core of polymer nanoparticles can not only validly avoid the leakage of fluorophores but also greatly enhance their brightness. Besides, this polymer nanoprobe (SPN) displays high water dispersibility, ultrafast response (1s), favorable selectivity, outstanding long-term stability (90 days), and good biocompatibility. Furthermore, thanks to the hepatocyte-targeting moiety (galactose) and the interplay of surface charge and size of nanoparticles, the SPN is able to enter into asialoglycoprotein receptor-positive HepG2 cells and further locate at lysosomes, successfully enabling accurate HClO detection in lysosomes of HepG2 cells. This study demonstrates that the versatile SPN can provide more precise dual-targeting and accurate molecular imaging.

Direct, in situ selective detection of intracellular formaldehyde (FA) is of great significance for understanding its function in FA-related diseases. Herein, red carbon dots (RCD) are reported as label-free two-photon fluorescent nanoprobes for detecting and imaging of FA. Upon addition of FA, the -NH2 groups of RCD could quickly and specially react with aldehydes to form Schiff base and then the strong fluorescence of RCD with blue-shift emission is recovery due to the destruction of the hydrogen bond interaction between RCD and water. In addition, the nanoprobes exhibit outstanding photostability, rapid response (

The rational design of a zero cross-talk self-referenced ratiometric fluorescent probe for accurate molecular imaging in living cells is still a major challenge. Herein, we report a zero cross-talk fluorescent polymer nanoprobe (named ZC-FPN) with a self-referenced ratiometric effect for lysosomal hypochlorous acid (HClO) imaging using single-wavelength excitation. The newly designed polymer nanoprobe (ZC-FPN) is prepared by using a simple co-precipitation method through self-assembly of two amphiphilic block copolymers, which are covalently linked with a porphyrin fluorophore (HClO-responsive unit) and a naphthalimide fluorophore (reference unit), respectively. Remarkably, the ZC-FPN displays an unprecedented separation of two emission peaks (∼191 nm), which can avoid the spectral cross-talk problem of the emission-shift type ratiometric probes and is highly favorable for high-resolution bioimaging. In addition, the as-prepared ZC-FPN also shows good water dispersibility, high selectivity, excellent long-term fluorescence stability (>10 weeks) and low cytotoxicity. More importantly, the positive charge of the amino moiety enhances the efficient uptake of the nanoprobe by cancer cells and enables the nanoprobe to selectively accumulate in lysosomes, achieving endogenous HClO imaging in living cells through fluorescence ratiometric imaging.

A novel amphiphilic fluorescence building block with perylene diimide (PDI) as the core and quadruple H-bonding groups (UPy) as wings (UPy–PDI–UPy) has been synthesized. It shows interesting thermo-responsive ratiometric dual-emission properties in both aqueous solution and the hydrogel state. Further contrast experiments with two other analogous derivatives, namely UPy–TPDI–UPy and TEG–PDI–TEG, indicated that the presence of supramolecular aggregation induced an emission enhancement effect between the UPy–PDI–UPy molecules, attributed to the synergetic effect of intermolecular intrinsic π–π stacking, the hydrophobic effect and highly directional quadruple H-bonding. In DMF/H2O (v : v = 1 : 1), UPy–PDI–UPy self-assembles into nanoparticles with obvious ratiometric fluorescence responsiveness towards temperature in the range of 20–80 °C. Moreover, UPy–PDI–UPy can form a thermo-responsive hydrogel by dispersing in PEG-containing aqueous solution. The hydrogels show a temperature-dependent ratiometric dual-emission with a narrow responsive range of 20–39 °C and an excellent renewable property. This innovative research helps to fabricate novel responsive luminescent materials by using the supramolecular self-assembly behavior.

The development of simple and effective tools for selective ratiometric detection of hypochlorite (ClO−) is one of the most important goals for elucidating the biofunction of ClO− in associated diseases. However, most developmental probes suffer from the notorious aggregation-caused quenching (ACQ) effect that greatly limits their applications. Herein, we report on novel aggregation-induced emission dots (AIED) for ratiometric detection of ClO− via a co-precipitation strategy. The AIED nanoprobe displayed a ratiometric signal output, which was more promising to minimize the bad environmental factors and simultaneously avoided the ACQ effect. Notably, amphiphilic block copolymer endowed the nanoprobe with stable water dispersibility and easy modification. The as-prepared AIED probe exhibited high sensitivity (~ 89 nM), high selectivity, outstanding photostability, and prominent long-term fluorescence stability. Furthermore, the as-prepared AIED was applied for the visualized fluorescence detection of ClO− and further utilized to detect ClO− in real samples. We expect the nanoprobe to be an outstanding tool to understand ClO−-associated diseases.

Photoswitchable fluorescent nanomaterials have received much attention due to their versatile applications but they normally do not show high-contrast red fluorescence. Herein, we report novel photoswitchable red fluorescent polymer nanoparticles (PRFPNs) based on fluorescence resonance energy transfer (FRET) from nile red (fluorescent donor) to spirothiopyran (photochromic acceptor). Both the donor and the acceptor are covalently incorporated into nanoparticles through a facile miniemulsion polymerization. The obtained PRFPNs exhibit not only reversible photoswitching of fluorescence characteristics under alternate UV and visible light irradiation, but also tunable FRET efficiency, favorable photoreversibility, excellent fluorescence stability, ultrahigh brightness and high contrast on/off fluorescence. We demonstrate that these PRFPNs can be used in rewritable information encryption, anti-counterfeiting and reversible fluorescence bioimaging in living cells.

The photoswitchable system with color and multi-state fluorescence changes is the key to the realization of advanced multi-level information storage, and its application potential has far exceeded the monochromatic fluorescent system. Herein, we introduced a novel multi-state photoswitchable fluorescent polymeric nanoparticles, which contains two energy-matched photoswitchable fluorescent molecules, i.e. diarylethene derivative (BH, donor) and spiropyran derivative (SPMA, acceptor), to construct a tunable fluorescence resonance energy transfer (FRET) system. By optimizing the feeding ratio of the two photochromic molecules to control the efficiency of energy transfer, the fluorescence of the nanoparticles can be reversibly switched among none, red, orange, and green by adjusting the wavelength of light stimuli. In addition, the nanoparticles display good water dispersibility, high brightness, fast responsiveness, excellent photoreversibility, and long-term fluorescence stability. We also verified that the system has great potential in optical data storage, multi-layer information encryption, and anti-counterfeiting.

This work describes a simple and sensitive fluorescent method for detection of hydroquinone utilizing conjugated polymer nanoparticles (CPNs). The CPNs serve both as a catalyst to accelerate the conversion of hydroquinone to benzoquinone and a fluorescent probe. In the presence of hydroquinone, the fluorescence of CPNs can be effectively quenched by benzoquinone. The detection limit of hydroquinone was down to 5 nM and excellent selectivity toward possible interferences was obtained. This method was successfully applied for hydroquinone detection in lake water and satisfactory results were achieved.

Stimuli-responsive fluorescent materials that can alternate their emission states on-demand are always desired in many applications. In this study, novel photoswitchable multistate fluorescent polymer (PMFP) was prepared via simple free-radical copolymerization of butyl acrylate (BA) and styrene (St) with two photochromic fluorescent monomers, i.e. sulfonyl diarylethylene-linked 4-hydroxybutyl acrylate (SDTE) and spiropyran-linked methacrylate (SP8). The PMFP displays excellent processability, due to its rational feed ratio of BA and St which result in the relative low glass transition temperature. By changing irradiation light, the non-fluorescent ring-closed spiropyran units and ring-opened diarylethylene moieties in PMFP can be selectively converted into their corresponding luminescence states. Furthermore, as a result of the controllable fluorescence resonance energy transfer (FRET) from the excited diarylethylene to the spiropyran moieties, the emission of the polymer in solution or film can be reversibly switched among distinguishable no-emission, red, and green fluorescence states. Moreover, the PMFP exhibits high brightness, high contrast, rapid photoresponse, and excellent photoreversibility. We also demonstrated that PMFP can be directly used for advanced high-density data storage, multilevel information encryption, and multicolor photorewritable pattern, as well as high-level anticounterfeiting.

A nanotheranostic system integrating activatable photoactivity and dual targeting modalities is significant for bioimaging and biomedicine. In this study, a dual-targeting and tumor microenvironment responsive nanoassembly for imaging of HAase and PDT of tumor was developed. The synthesized water-soluble cationic porphyrin act as both the mitochondrion targeting photosensitizer and crosslinking agent to trigger the formation of HA-Mito TPP nanoparticle via the electrostatic interaction with hyaluronic acid. The nanoassembly could be efficiently endocytosed into targeted tumor cells and activated both fluorescence signal and enhanced PDT effect by highly expressed HAase. In vitro experiments suggested that the reported assay had desirable selectivity and excellent anti-interference for HAase quantitative analysis. The live cell studies showed the HA-Mito TPP had obviously enhanced PDT efficiency and caused mitochondria damage. Therefore, the developed dual-targeting nanotheranostic system provide a promising platform for bioanalysis and imaging guided photodynamic therapy.

Color-specific photoswitchable dual-emissive systems are highly desirable for encryption, bioimaging and other applications. However, it is difficult to design ideal systems with ultrahigh switching efficiency and none overlap of emission signals. Herein, we report a class of zero-crosstalk dual-emissive polymer nanoparticles (ZDPNs) showing fully color-specific photoswitching property. ZDPNs contain a photochromic fluorescent diarylethene (DBTEO) and a fluorescent tetraphenylporphyrin (TPP) dye. TPP displays large Stokes shift and none spectral overlap with ring-closed form of DBTEO and therefore, blocked energy transfer effect is achieved. Upon irradiation of different lights, cyan emission of DBTEO is 100% photo-switched, while the red fluorescence from TPP is constant. Polymer nanoparticles with different photoswitchable dual-emissive signals can be prepared by simply adjusting the feeding ratio of DBTEO and TPP. In addition, taking advantages of the facile synthesis, good water dispersibility, high-contrast of dual-emissive signals, prominent photoreversibility and photostability of the as-prepared nanoparticles, these nanoparticles exhibit great potentials in multiple applications including information encryption, anti-counterfeiting, photo-rewritable patterning and cancer cell-targeted dual-color bioimaging.

Hypochlorite (ClO − ) and temperature play crucial roles in a wide range of physiological processes, and they are also implicated in various diseases, including cancer, inflammation of tissues and so on. Therefore, it is of great importance to explore a novel method to detect ClO − and temperature instantly. In this study, we developed a silica nanoparticle-based dual-responsive ratiometric fluorescent sensor (DRFS), whose correlative dual emissions can response to ClO − and temperature independently and sensitively. The detection limit of DRFS can reach to as low as 26 nM for the detection of ClO − . And further research demonstrates that DRFS possesses excellent anti-interference feature when other possible interferents exist, and has been successfully applied in ClO − detection in human serum and recognition of exogenous/endogenous ClO − in HeLa cells and macrophages by fluorescence microscopic imaging. Moreover, DRFS can also be used as a ratiometric temperature sensor, and the fluorescence intensity ratio (I 576 /I 445 ) exhibits a linear temperature response in the range from 20 to 60 °C with a change ratio as large as a factor of 5. Based on the above research, the DRFS can be used as versatile fluorescence sensor in various physiological and environmental systems.

To explore new practical means of alleviating the negative effect of heat stress on rice plants during the heading-flowering stage, a field experiment was conducted in Ji'an, Yugan, and Nanchang counties of Jiangxi Province from 2017 to 2018 with three indica hybrid rice varieties. Under ambient high temperature condition during the heading-flowering period, we sprayed five concentrations of salicylic acid (SA) (SA为探寻减轻水稻抽穗开花期高温热害的技术途径,以3个籼型杂交稻品种为材料,于2017—2018年在江西省吉安县、余干县、南昌县进行田间试验.在抽穗开花期自然高温下,设置叶面喷施5个不同浓度的水杨酸(SA)处理(SA

Efficient platforms for intracellular delivery of nucleic acids are essential for biomedical imaging and gene regulation. We develop a recombinant fusion streptavidin as a novel protein scaffold for DNA nanotetrads for highly efficient nucleic acid delivery and telomerase activity imaging in living cells via cross-linking hybridization chain reaction (cHCR). The recombinant streptavidin protein is designed to fuse with multiple SV40 NLS (nuclear localization signal) and NES (nuclear export signal) domains and prepared through Escherichia coli expression. The recombinant NLS-SA protein allows facile assembly with four biotinylated DNA probes via high-affinity noncovalent interactions, forming a well-defined DNA tetrad nanostructure. The DNA nanotetrads are demonstrated to confer efficient cytosolic delivery of nucleic acid via a caveolar mediated endocytosis pathway, allowing efficient escape from lysosomal degradation. Moreover, the nanotetrads enable efficient cHCR assembly in response to telomerase in vitro and in cellulo, affording ultrasensitive detection and spatially resolved imaging for telomerase with a detection limit as low as 90 HeLa cells/mL. The fluorescence brightness obtained in live cell imaging is found to be dynamically correlated to telomerase activity and the inhibitor concentrations. Therefore, the proposed strategy may provide a highly efficient platform for nucleic acid delivery and imaging of biomarkers in living cells.

A novel isothermal nucleic acid amplification technology is developed by coupling catalytic hairpin assembly with enzymatic repairing amplification as a highly sensitive and selective platform for miRNA detection.

We developed novel activatable probe using self-assembled peptide nanowires with low affinity and toxicity to tumor cells in the absence of matrix metalloproteinase that showed activated high affinity and toxicity and provided a highly selective and efficient platform for targeted therapy and tumor imaging.

Recent studies have shown that water-soluble fluorescent dyes can be used as miniemulsion stabilizers to avoid a series of deficiencies in traditional stabilizers. However, visual means to demonstrate the stabilizing performance of water-soluble dyes are still scarce. In this study, the principle of fluorescence resonance energy transfer (FRET) is combined with dual emission of fluorescent polystyrene nanoparticles prepared by miniemulsion polymerization. For this purpose, 4-(1,2,2-triphenylethyl) phenylundecene-10-enoate (TPE-Aly) was employed as aggregation induced emission (AIE) dye and donor and Eosin Y as acceptor and stabilizer. The polymer molecular weight, particle size and size distribution of the nanoparticles were optimized by regulating the amount of Eosin Y and ultrasonication time, respectively. The average number of Eosin Y molecules per nanoparticle was firstly estimated by combining dialysis and Lambert-Beer law. FRET between TPE-Aly and Eosin Y indicates the presence of Eosin Y on the surface of the polymer nanoparticles. With increasing concentration of Eosin Y, the as-prepared dual-emission nanoparticles display a decreasing particle size along with an enhancing FRET efficiency. Moreover, various stability tests show that Eosin Y can be used as an excellent stabilizer for miniemulsion polymerization and has broad application prospects in the field of functional materials research.

The design of novel ratiometric nanoprobes with two well-resolved fluorescence bands for accurate imaging of lysosomal hypochlorous acid (HClO) is significant to understand its biological and pathological behaviors. Herein, we develop a single-dye-doped self-referenced ratiometric nanoprobe (SSRN) for imaging of HClO in lysosomes under a single-wavelength excitation (λex = 405 nm). The referenced unit (benzothiazole moiety) and HClO-responsive unit (rhodamine B) are integrated into the single dye (HB-Py) to achieve the self-referenced ratiometric effect. The well-dispersed SSRN are prepared by a simple coprecipitation of the morpholine moiety modified amphiphilic polymers (CO-720-MA) and HB-Py. Of note, the two well-resolved fluorescence bands (∼130 nm) of SSRN could provide accurate imaging of analyte in live cells. Additionally, other distinct merits with SSRN are also simultaneously realized, including high water solubility, high sensitivity (detection limit: 52 nM), excellent selectivity, good biocompatibility and excellent photostability. Significantly, benefiting from the morpholine moiety, this nanoprobe SSRN can specially locate lysosomes and enable ratiometric imaging of exogenous/endogenous HClO in lysosomes.

To explore the possible long-term health effects of the defoamer used in seawater desalination by sub-chronic toxicity testing.Blood analysis, internal organ assessment, and histopathological examination were carried out in rats exposed to low, medium, and high (0.5, 1.0, and 2.0 g/kg BW, respectively) doses of defoamer for 90 days through oral administration.The high dose group showed decreased blood alanine aminotransferase and aspartate aminotransferase (P0.05). All doses resulted in a significant increase in albumin and decrease in globulin (P0.05). The direct bilirubin and indirect bilirubin were decreased in the medium and high dose groups (P0.05). All dose groups showed significant induction of alkaline phosphatase (P0.05). Pathological examination revealed a case of liver mononuclear cell infiltration in the medium dose group and three cases of liver congestion, steatosis of hepatic cells around the central vein, and punctate necrosis with multiple focal mononuclear cell infiltration in male rats administered the high dose. The No Observed Adverse Effect Level was 0.5 g/kg BW in rats, with albumin and total bilirubin as health effect indices.Long-term defoamer exposure may cause liver injury but has no significant impact on renal function in rats. The effect on blood cells in female rats was more prominent than that in male rats.

Unique physicochemical characteristics of graphitic carbon nitride (g-CN) nanosheets suit them to be a useful tool for two-photon fluorescence bioimaging. Current g-CN nanosheets based imaging probes typically use the "always-on" design strategies, which may suffer from increased fluorescence background and limited contrast. To advance corresponding applications, g-CN nanosheets based activatable two-photon fluorescence probes remain to be explored. For the first time, we developed an activatable two-photon fluorescence probe, constructed from a nanoassembly of g-CN nanosheets and hyaluronic acid (HA)-gold nanoparticles (HA-AuNPs), for detection and imaging of hyaluronidase (HAase) in cancer cells. The deliberately introduced HA in our design not only functions as the buffering layer for stabilizing AuNPs and inducing corresponding self-assembly on g-CN nanosheets but also as a pilot for targeting HA receptors overexpressed on cancer cell surfaces. Our results show that the developed nanoassembly enables specific detection and activatable imaging of HAase in cancer cells and deep tissues, with superb signal-to-background ratio and high sensitivity. This nanoassembly can afford a promising platform for highly specific and sensitive imaging of HAase and for related cancer diagnosis.

A novel ICP MS DNA assay based on lanthanide labels and hybridization chain reaction amplification has been developed. This approach utilizes an enzyme-free amplification and can be operated under mild conditions. The developed assay exhibits desirable sensitivity and is suitable for multiple DNA target analysis because a general DNA hybridization approach is applied to capture target DNA. Considering lanthanide labels and ICP-MS have excellent ability in high-level multiplexing analysis, this approach holds great potential for practical use in quantitative determination of DNA targets for future clinical applications.

1. Herbicide atrazine (ATR) poses harmful effects on human health. The purpose of this study is to study potential biomarkers used for monitoring the toxic effects after chronic exposure to ATR by studying urine metabolites. 2. Rats were assigned into clinical chemistry and metabonomics arms, and each arm was divided into low-dose, high-dose and control groups. ATR was administered to rats along with their feed. At the end of 16, 20 and 24 weeks, clinical parameters and histopathologic changes was assessed to monitor the toxic effects. Twenty-four hour urine samples was analyzed by UPLC-MS, to find the significant alterations in metabolic profiling. 3. The body weight of rats in ATR group was lower than that of control starting from 12th week; abnormal levels of serum biochemistry and histopathologic alterations of organs were found initially from 16th and 20th week, respectively. Five exogenous and five endogenous metabolites were found which showed significant differences between ATR groups and control group at above-mentioned time points. 4. These metabolites may be used as potential indicators to monitor ATR toxicity, and also may provide some clues for understanding the mechanism of toxicity of ATR. The exact relationship between endogenous metabolites and ATR toxicity needs further investigation.

It is of great value to develop a simple, rapid, label-free and sensitive strategy for tyrosinase activity detection and corresponding inhibitor screening in both biomedical diagnosis and cosmetic industry. However, many recently reported fluorescent assays may suffer from instability to light irradiation, poor water solubility, and complex modification. Herein, a novel fluorescent biosensor strategy has been developed capable of sensitive, label-free and rapid screening of tyrosinase activity as well as corresponding inhibitors based on fluorescent block copolymer nanoparticles (BCNs). The reported BCNs were prepared by coprecipitation assay using the mixture of amphiphilic block copolymer and fluorescent conjugated polymer, which show many advantages including high brightness, excellent photostability and biocompatibility, enabling the biosensor with high sensitivity and good reproducibility in a single-step operation. The reported assay exhibited high sensitivity and selectivity with a detection limit of 1.5 ng/mL for tyrosinase (TRY) activity detection and hold potential in its inhibitor screening. The satisfying recoveries offered great potential for complicated sample analysis. Hence, this reported assay may provide a novel platform for biosensor development.

We report the development of a novel plasmon coupling enhanced Raman scattering (PCERS) method, PCERS nanobeacon, for ultrasensitive, single-step, homogeneous detection of cholera toxin (CT). This method relies on our design of the plasmonic nanoparticles, which have a bilayer phospholipid coating with embedded Raman indicators and CT-binding ligands of monosialoganglioside (GM1). This design allows a facile synthesis of the plasmonic nanoparticle via two-step self-assembly without any specific modification or chemical immobilization. The realization of tethering GM1 on the surface imparts the plasmonic nanoparticles with high affinity, excellent specificity, and multivalence for interaction with CT. The unique lipid-based bilayer coated structure also affords excellent biocompatibility and stability for the plasmonic nanoparticles. The plasmonic nanoparticles are able to show substantial enhancement of the surface-enhanced Raman scattering (SERS) signals in a single-step interaction with CT, because of their assembly into aggregates in response to the CT-sandwiched interactions. The results reveal that the developed nanobeacon provides a simple but ultrasensitive sensor for rapid detection of CT with a large signal-to-background ratio and excellent reproducibility in a wide dynamic range, implying its potential for point-of-care applications in preventive and diagnostic monitoring of cholera.

We have developed a novel concept for enzymatic control of plasmonic coupling as a surface enhanced Raman scattering (SERS) nanosensor for DNA demethylation. This nanosensor is constructed by decorating gold nanoparticles (AuNPs) with Raman reporters and hemimethylated DNA probes. Demethylation of DNA probes initiates a degradation reaction of the probes by methylation-sensitive endonuclease Bsh 1236I and single-strand selective exonuclease I. This destabilizes AuNPs and mediates the aggregation of AuNPs, generating a strong plasmonic coupling SERS signal in response to DNA demethylation. This nanosensor has the advantages in its high signal-to-noise ratio, superb specificity, and rapid, convenient, and reproducible detection with homogeneous, single-step operation. Thus, it provides a useful platform for detecting DNA demethylation and related molecular diagnostics and drug screening. This work is the first time that enzymatic degradation of DNA substrate probes has been utilized to induce aggregation of AuNPs such that reproducible, sensitive SERS signals can be achieved from biological recognition events. This enzymatic control mechanism for plasmonic coupling may create a new paradigm for the development of SERS nanosensors.

To study whether apoptosis plays a role in controlling the number of olfactory receptor neurons, so as to reveal the specialty and mystery of neurogenesis.Using terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick end labeling (TUNEL) and transmission electron microscopy to detect apoptosis in olfactory mucosa of normal adult rats and damaged olfactory mucosa of 16, 32, 48 hours and 3, 7, 30 days after bulbectomy.In normal olfactory epithelium, a subpopulation of immature neurons, as well as mature neurons, showed internucleosomal DNA-fragmentation. The number of TUNEL-labeled neurons increased dramatically 32 hours after removal of olfactory bulb. Then it declined quickly and remained at low level. Ultrastructural data of olfactory mucosa showed that the feature of apoptotic neurons was chromatin condensation and cell shrinkage. Besides, some dying cells were characterized by the formation of numerous autophagic vacuoles, and few had some of the features of necrosis but without obvious mitochondrial swelling.Apoptosis might play a role in turnover of the olfactory epithelium and regeneration in adult rats. There might be other two types of neural death through different mechanism.

Poled polymer and acentric Langmuir-Blodgett films represent promising approaches to high-efficiency second harmonic generation (SHG) materials. Nevertheless, net achievable nonlinear optical (NLO) chromophore alignments, number densities, and alignment temporal stabilities are significant issues in the former materials, as are scattering microdomains, structural stability, and structural regularity, in the latter. The authors communicate here an alternative approach to thin-film NLO materials utilizing the sequential construction of covalently self-assembled chromophore-containing multilayer structures.