STUDIES ON CROWN ETHER CYANINE DYES (X). THE SYNTHESIS OF BENZOXAZOLE CROWN ETHER CYANINE DYES

A simple method for synthesis of benoxazole crown ether cyanine dyes is described.

STUDIES ON CROWN ETHER CYANINE DYES(XI)THE SYNTHESIS OF BENZOTELLURAZOLE CROWN ETHER CYANINE DYES

Three methods for synthesis of benzotellurazole crown ether(6)are described.The cyanine dye(8)can be easily obtained by treating(6) with CH_3I and CH(OEt)_3.

Highly Efficient Photosensitization of Mesoporous TiO_2 Electrode with a Cyanine Dye

A low cost cyanine dye, 1,1-dimethyl-3-ethyl-2-[3-(1,3-dihydro-3,3-dimethyl-1-ethyl- 5-carboxyl-2H-indol-2-ylidene)-1-propenyl]-1H-benz[e] indolium iodide (1) was synthesized and applied to sensitize mesoporous TiO2 electrode. Photoresponse of the electrode was extended to the visible and remarkably high incident photon-to-current conversion efficiency (IPCE) over 70% was achieved from 500 nm to 600 nm.

DFT Investigation on the Trans-cis Photoisomerization of Pentamethine Cyanine Dye Model Molecule

The trans-cis photoisomerization of pentamethine cyanine dye （Cy5） has been theoretically investigated by the analysis on an analogical molecule model. All possible isomers have been searched by rotating the different bridge C-C bonds of the model. The relative stability of the isomers for the ground and first excited states as well as the corresponding excitation mechanism has been envisaged by DFT and time-dependent DFT method. The results show different conjugation degree of the isomers resulting in different absorption energy upon the different C-C bridge bond rotation. From the analyses of electronic density distribution of the frontier orbitals, it is predicted that there is charge transfer besides the π-π^＊ excitation for the cyanine dye model, which makes the mechanism and photo-properties different form those of other conjugated molecules.

Synthesis and Characterization of a Squarylium Cyanine Dye with Two [60]Fullerene Units

A new [60]fullerene dimer 2 in which two C-60 units are covalently attached to a squarylium cyanine dye has been synthesized and characterized.

Study on the Direct Photooxidation of Near-Infrared Absorbing Benzothiazolone Cyanine Dye

In this paper, direct photooxidation of benzothiazolone cyanine dye: in acetonitrile was studied. The photoproducts had been identified by (HNMR)-H-1 and fast atom bombardment (FAB) mass spectrometry. The results showed that the N-ethylbenzothiazolone (I), the ionic acid (II), and ionic aldehyde (III) are the principal photoproducts.

Squarylium Cyanine Dyes for Photoelectric Conversion

Two squarylium cyanine dyes (Sqs) were synthesized to explore their applications in photoelectrochemical solar cells. Nanocrystalline TiO2 electrodes modified with Sqs have been prepared to probe the photosensitization effects. A rather high photoelectric conversion efficiency of up to 2.17% and the top incident monochromatic photon-to-photocurrent conversion efficiency (IPCE) of 6.2% at 650nm were obtained from the Sq2-modified nanocrystalline TiO2 electrode.

Investigation of a cyanine dye assay for the evaluation of the biocompatibility of magnesium alloys by direct and indirect methods

Magnesium and its alloys are promising candidates for a new generation of biodegradable metals in orthopaedic applications due to their excellent biocompatibility,biodegradability,and mechanical properties that are similar to natural bone.However,direct in vitro assessment of these materials in the presence of cells is complicated by degradation products from the alloy that lead to a false positive for the most commonly used cell adhesion and cell proliferation assays.In this paper,a cyanine dye was used to quantitatively evaluate the in vitro biocompatibility of a Mg AZ31 alloy by both direct and indirect methods.The cytotoxicity of the corrosion products was evaluated via an indirect method;a 25%decrease in cell viability compared to control samples was observed.Moreover,direct assessment of cell adhesion and proliferation showed a statistically significant increase in cell number at the surface after 72 h.In addition,the degradation rate and surface characteristics of the Mg AZ31 alloy were evaluated for both direct and indirect tests.The degradation rate was unaffected by the presence of cells while evidence of an increase in calcium phosphate deposition on the magnesium alloy surface in the presence of cells was observed.This study demonstrates that a cyanine dye based assay provides a more accurate assessment of the overall in vitro biocompatibility of biodegradable metals than the more commonly used assays reported in the literature to date.

Synthesis and light absorption of benzotellurazole crown ether cyanine dye

Various methods for synthesis of 2-methyl-5,6-(1,4, 7,10,13-pentaoxatridecamethylene)benzotellurazole (8) are described. Under different conditions, alkylation of compound 8 with methyl iodide gave telluronium salt 1,2-dimethyl-5,6-(1,4,7,10,13-pentaoxatridecamethylene)benzotellurazolium iodide (15) or quaternary ammonium salt 2,3-dimethyl-5,6-(1,4,7,10,13-pentaoxatridecamethylene)benzotellurazolium iodide (14) in high yields, repectively. The cyanine dye 3,3'-dimethyl-5,6,5',6'-bis(1,4,7,10,13-pentaoxatridecamethylene)telluracarbocyanine iodide (16) is obtained by condensation of 14 with ethyl orthoformate in acetic anhydride, The visible absorption of the cyanine dye is also discussed.

Synthesis and Absorption Characteristics of Two Infrared Cyanine Dyes

Two infrared dyes, 1,3,3,1′, 3′, 3′ hexamethylindotricarbocyanine iodide (A) and 1,3,3,1′,3′,3′ hexamethyl 11 chloro 10,12 propylenetricarbocyanine iodide (B), were synthesized and characterized by melting point, elemental analysis, IR, and 1 H NMR. Their electron absorption spectra, laser absorption characteristics and solubility were investigated. The results showed that A and B have maximum absorption peaks at around 748nm and 774nm, respectivey, which match well with the wavelength output of the near infrared laser diode. The dyes were found to have photoinduced fading during irradiation with the infrared laser, especially in the presence of oxygen. However, this procession can be greatly slowed by using a layer of poly(vinyl alcohol) to barricade the dyes from oxygen. The experiments also showed that the dyes were thermally stable but decayed under strong sunlight. Furthermore, they are easily dissolved in some common solvents.

One-Pot Preparation of Highly Dispersed Second Near-Infrared J-Aggregate Nanoparticles Based on FD-1080 Cyanine Dye for Bioimaging and Biosensing

Bioimaging and biosensing in the second nearinfrared(NIR-II)window have attracted great attention due to their unprecedented high temporal–spatial resolution,sensitivity,and penetration depth.Although some organic fluorescence dyes have been developed in this window,it is still a great challenge to synthesize hydrophilic organic contrast agents with both absorbance and emission wavelengths beyond 1300 nm.J-aggregation is a facile pathway to achieve the wavelength red-shift of organic dyes to the NIR-II window and simultaneously improve their hydrophilicity.Here,we report FD-1080 J-aggregates(FD-J)with absorbance of 1360 nm and emission of 1370 nm through heating H-aggregated FD-1080 cyanine dyes in an aqueous solution.With FD-J administration,real-time imaging of mice brain and hindlimb vasculatures can be performed beyond 1500 nm.Meanwhile,arterial and venous vessels can be clearly distinguished through dynamic imaging after injection of FD-J.In addition,reactive oxygen species-responsive NIR-II ratiometric fluorescence sensors were available based on FD-J and lanthanide nanoparticles to enable the detection of inflammation in living mice.

Recognizing parallel-stranded G-quadruplex by cyanine dye dimer based on dual-site binding mode

G-quadruplexes （G4s） play important roles in biological systems, such as telomere maintenance, replication, and transcription. Based on the DNA sequence, loop geometry, and the local environments, G4s can be classified into different conformations. It is important to detect different types of G4s to monitor the diseases related with G4s. Most ligands bind to G4s based on end-stacking modes, while rare ligands bind to G4s through groove binding modes. We have found that a cyanine dye DMSB interacts with parallel G4 by end-stacking and groove simultaneous binding mode. In this article, we found that DMSB could simply discriminate parallel G4s from other DNA motifs by using UV-vis spectrum. These results give some clues to develop high specificity G4 probes.

Anisotropy in Third-Order Nonlinear Optical Susceptibility of a Squarylium Dye in a Nematic Liquid Crystal

A squarylium dye is dissolved in 4-cyano-4＇-pentylbiphenyl （SCB） and oriented by sandwiching mixtures between two pieces of rubbed glass plates. The optical absorption spectra of the oriented squarylium dye-5CB layers exhibit high anisotropy. The third-order nonlinear optical responses and susceptibilities X^（3）e of squarylium dye in 5CB are measured with light polarizations parallel and perpendicular to the orientational direction by the resonant femtosecond degenerate four-wave mixing （DFWM） technique. Temporal profiles of the DFWM signal of the oriented squarylium dye-5CB layers with light polarizations parallel and perpendicular to the orientational direction are measured with a time resolution of 0.3ps （FWHM）, and are found to consist of two components, i.e., the coherent instantaneous nonlinear response and slow response due to the formation of excited molecules. A high anisotropic ratio of x^（3）e, 10.8 ：k 1.2, is observed for the oriented layers.

HSA shrinkage optimizes the photostability of embedded dyes fundamentally to amplify their efficiency as photothermal materials

Focused on the performance promotion of organic small molecular dyes based photothermal agents via non-chemical modification,we found that heat-assisted binding of human serum albumin(HSA)to the dye causes shrinkage of the protein and encapsulate the dye to form nanoparticles.This revolutionizes the photostability of small molecule dyes which further improves their photothermal conversion effi-ciency and tumor ablation performance as photothermal agents significantly.In this work,the obtained photothermal agent named HSA-P2-T could accumulate in tumor and induce 22℃enhancement of the tumor in xenograft models upon ultra-low dose(0.1 W/cm^(2))laser irradiation,which,as far as we know,is the lowest laser dose used in vivo photothermal therapy.Utilizing HSA-P2-T,we realized tumor ablation upon twice intravenous injections of the nanoparticles and four photothermal treatments.

A Cyanine-based Liposomal Nanophotosensitizer for Enhanced Cancer Chemo-Photodynamic Therapy

Currently,chemotherapy is one of the most important treatment modalities for malignant tumors in the clinic,however,it exhibits some shortcomings,such as poor selectivity,limited efficacy and serious adverse effects.Therefore,synergistic therapy and accurate drug delivery at tumor sites become a promising strategy for achieving tumor eradication.Herein,a smart NIR fluorescence imaging-guided nanoliposome was fabricated by encapsulating a chemotherapeutic drug(doxorubicin,DOX),liposomes(L)and a near-infrared(NIR)photosensitizer(CY)to form L@CY@DOX,which could realize enhanced therapeutic efficacy of chemo-PDT in cancer therapy(PDT=photodynamic therapy).L@CY@DOX can induce mitochondrial apoptosis and produce severe toxicity at the cellular level,and L@CY@DOX can enrich in the tumor site,which significantly induces tumor death.In vitro and in vivo studies demonstrated that L@CY@DOX exhibited great antitumor efficacy compared with each one of these monotherapies,indicating that the combination of chemotherapy and PDT possessed potential development prospects and is anticipated in clinical application.

Optical recording of brain functions based on voltage-sensitive dyes

To better understand the spatial distribution of brain functions,we need to monitor and analyze neuronal activities.Electrophysiological technique has provided an important method for the exploration of some neural circuits.However,this method cannot simultaneously detect the activities of nerve cell groups.Therefore,methods that can monitor the spatial distribution of neuronal population activity are demanded to explore brain functions.Voltage-sensitive dyes(VSDs)shift their absorption or emission optical signals in response to different membrane potentials,allowing assessing the global electrical state of neurons.Optical recording technique coupled with VSDs is a promising method to monitor the brain functions by detecting optical signal changes.This review focuses on the fast and slow responses of VSDs to membrane potential changes and optical recordings utilized in the central nervous system.In this review,we attempt to show how VSDs and optical recordings can be used to obtain brain functional monitoring at high spatial and temporal resolution.Understanding of brain functions will not only greatly improve the cognition of information transmission of complex neural network,but also provide new methods of treating brain diseases such as Parkinson’s and Alzheimer’s diseases.

PEG-PCLnanomicelles for cancer theranosis:targeted imaging and drug delivery

Nanomicelles,self-assembling nanosized particles with a hydrophobic core and hydrophilic shell,are currently successfully used as carriers for targeted drug delivery systems via the enhanced permeability and retention（EPR） effect at the tumor sites.In this study,a near-infrared fluorescent cyanine dye（Cy7-NHS） was conjugated to poly（ethylene glycol）-block-poly（ε-caprolactone）（NH 2-PEG-b-PCL）,and the resulting Cy7-PEG-PCL was further mixed with mPEG-b-PCL to form nanomicelles as carriers for paclitaxel（PTX） delivery.Our results showed that the selected mPEG 4000-b-PCL 2500 copolymers self-assembled to form stable micelles with an average size of 30 nm in diameter and a zeta potential of approximately-3 mV.The micelles also exhibited more than 95% encapsulation efficiency of PTX when the molar ratio between paclitaxel and copolymers was 1/4.In vitro cytotoxicity study showed that the PTX-loaded nanomicelles had a similar cell growth inhibition efficacy to that of Taxol against human breast cancer MCF-7 cells.In vivo imaging showed that the Cy7-labeled nanomicelles could be passively targeted to tumor sites effectively after intravenous injection via the tail vein.Also,a strong anti-tumor activity was observed in the nude mice xenografted MCF-7 breast tumor after treatment with PTX-loaded micelles,similar to that of Taxol.As a result,the micelle drug delivery system designed in this paper has great potential in targeted imaging of tumors and chemotherapy.

Roles of flanking sequences in the binding between unimolecular parallel-stranded G-quadruplexes and ligands

G-quadruplexes attract more and more attention in recent years.Numerous small molecules which can induce or stabilize the formation of G-quadruplexes have been investigated on the purpose of anticancer drug development.As a motif existed in physiological condition,flanking sequences are an important part of G-quadruplexes but the study on the impact of flanking sequences on (G-quadruplex)-ligand binding is rarely reported.In this paper,the effects of flanking sequences on binding affinity between a series of unimolecular parallel-stranded G-quadruplex sequences derived from c-myc oncogene promoter (termed as c-myc G-quadruplexes) and their ligands are discussed in detail.The results showed that the flanking sequences on c-myc G-quadruplexes play key roles in (G-quadruplex)-ligand interaction.When a c-myc G-quadruplex is bound to its ligands,the flanking sequences might form a binding cavity above the terminal G-quartet,which could provide a suitable site for ligands to dock in.Moreover,the bases on flanking sequences could interact with ligand through π-π stacking,and finally form a sandwich-stacking mode (terminal G-quartet,ligand and bases on the flanking sequence).This mode could stabilize the (G-quadruplex)-ligand complex effectively and enhance the binding affinity dramatically.However,flanking sequences are also found to exhibit steric hindrance effect which could impede the (G-quadruplex)-ligand binding.