STUDY ON ENHANCEMENT OF TUMOR-KILLING EFFECT AND FORMATION OF NEW FLUOROPHORE IN TUMOR CELLS

Hyperthermia (42-44℃) and photosensitizing therapy can destroy S180 tumor cells,reducemalignant ascites and prolong the survival times of mice with carcinomas.The highestcurative effect was observed when using a combination of the two treatments.Heating to44℃ has a greater destructive effect on tumor cells than has heating to 42℃.The resultsshow that this is due to a synergistic interaction between these two treatments.The fluores-cence spectrum of S180 cells was determined before and alter treatment,and the indicationwas that the synergistic effect is probably related to a new fluorescence product;the greaterthe intensity of the new fluorescence、the more marked the synergy of hyperthermia andphotosensitizing therapy.The maximum emission wavelength was 460nm (excitation wave-length 370nm).

Influence of sulfur doping on the molecular fluorophore and synergistic effect for citric acid carbon dots

In citric acid-based carbon dots,molecular fluorophore contributes greatly to the fluorescence emission.In this paper,the nitrogen and sulfur co-doped carbon dots(N,S-CDs)were prepared,and an independent sulfur source is selected to achieve the doping controllability.The influence of sulfur doping on the molecular fluorophore was systematically studied.The introduction of sulfur atoms may promote the formation of molecular fluorophore due to the increased nitrogen content in CDs.The addition surface states containing sulfur were produced,and S element exists as-SO_(3),and-SO_(4)groups.Appreciate ratio of nitrogen and sulfur sources can improve the fluorescence emission.The photoluminescence quantum yields(PLQY)is increased from 56.4%of the single N-doping CDs to 63.4%of double-doping CDs,which ascribes to the synergistic effect of molecular fluorophores and surface states.The sensitivity of fluorescence to pH response and various metal ions was also explored.

Folded or nonfolded fluorophores incorporating naphthalene:Their fluorescent quenching driven by charge transfer or co-aggregation in the aqueous-organic binary solvent

Folded or nonfolded fluorophores incorporating naphthalene were synthesized and characterized by steady state fluorescence technique.Paraquat as an excellent quenching reagent quenched the fluorescence of Nel6 or nDs(n = 1-4) driven by charge transfer.Under aggregation of nDs,α-CD did not quench the fluorescence of 1D.At lower concentration,the quenching tendency ofα-CD against nDs is 2D>3D>4D,while at higher concentration,the tendency is 2D<3D<4D.α-CD showed the selective recognition on its flu...

Synthesis of a Fluorophore with Improved Optical Brightness

The synthesis and characterization of a novel fluorophore(1), with potential application as an optical brightener are reported. This compound was prepared by reacting 4,4-diaminostilbene-2,2-disulfonic acid with cyanuric chloride in the presence of Na2CO3 followed by the addition of trityl aniline. Solution and solid state fluorescence demonstrated a strong blue/purple emission centered at 450 nm. 1H-NMR spectroscopy, mass spectrometry analysis, elemental analysis, and DOSY-NMR were used for the characterization of the fluorophore.

Progress and Challenges of Water-soluble NIR-II Organic Fluorophores for Fluorescence Imaging In vivo

The small-molecule fluorophores for the second near-infrared(NIR-II,1000–1700 nm)window have attracted increasing attention in basic scientific research and preclinical practice owing to their deep-photo penetration,minimal physiological toxicity and simplicity of chemical modification.However,most of the reported small-molecule NIR-II fluorophores suffered from poor water solubility,which can easily cause organ toxicity.In addition,the aggregation caused by their poor water solubility in the aqueous solution would also result in weak fluorescence of these NIR-II fluorophores.Thus,it is highly desirable and valuable to develop water-soluble small-molecule NIR-II fluorophores with excellent photophysical properties for high-contrast in vivo imaging.In this review,we summarize the recent research advances in water-soluble small-molecule NIR-II fluorophores and highlight the representative bioimaging applications.Moreover,the potential challenges and perspectives of water-soluble small-molecule NIR-II fluorophores are discussed as well.We anticipate this review can help researchers to grab the latest information of water-soluble small-molecule fluorophores for NIR-II imaging,sequentially boosting their further development.

Furan-modified thiadiazolo quinoxaline as an electron acceptor for constructing second near-infrared aggregation-induced emission fluorophores for beyond 1300 nm fluorescence/photoacoustic imaging and photothermal therapy

Creation of new fluorophores is important for understanding the structure-property relationship,by which the required optical properties are likely to be attained.Herein,through theory calculation,it is found that furan-modified thiadiazolo quinoxaline acting as an electron acceptor can endow donor-acceptor-donor(D-A-D)type second near-infrared(NIR-Ⅱ)fluorophores with longer emission wavelength than the other thiadiazolo quinoxaline-based acceptors containing pyridine,pyrrole,thiophene,and phenyl groups,respectively.On the basis of this theoretical prediction,a D-A-D type NIR-Ⅱ fluorophore with 6,7-di(furan-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline(DFTQ)as the acceptor and dithieno[3,2-b:2′,3′-d]pyrrole(DTP)as the donor is designed and synthesized,and the aggregation-induced emission(AIE)function is further achieved by introducing the AIE units of tetraphenylethylene(TPE)and triphenylamine(TPA),respectively,totally forming three NIR-Ⅱ fluorophores DFTQ-DTP,DFTQ-DTPE,and DFTQ-DTPA.For biological applications,the fluorophores are encapsulated by amphiphilic DSPE-PEG2000 to generate water-dispersible nanoparticles(NPs).Almost the whole emission of each of the NPs falls into the NIR-Ⅱ spectral range,with part emission beyond 1300 nm.By using DFTQ-DTPA NPs as the contrast and photothermal therapy(PTT)agent,high-resolution in vivo fluorescence imaging is achieved in the greater than 1300 nm window,and their good performance in photoacoustic imaging and high tumor PTT efficacy in tumor-bearing mice are also demonstrated.Taken together,this work mainly provides a strong electron acceptor for constructing longemitting fluorophores,and by using the electron acceptor,a AIE fluorophore with desirable quantum yield(QY)and photothermal conversion efficienciy(PCE)is synthesized and demonstrated to be promising in fluorescence/photoacoustic imaging and PTT.

Installing hydrogen bonds as a general strategy to control viscosity sensitivity of molecular rotor fluorophores Special Collection:Aggregation-Induced Processes and Functions

Molecular rotor-based fluorophores(RBFs)activate fluorescence upon increase of micro-viscosity,thus bearing a broad application promise in many fields.However,it remains a challenge to control how fluorescence of RBFs responds to viscosity changes.Herein,we demonstrate that the formation and regulation of intramolecular hydrogen bonds in the excited state of RBFs could modulate their rotational barrier,leading to a rational control of how their fluorescence can be activated by micro-viscosity.Based on this strategy,a series of RBFs were developed based on 4-hydroxybenzylidene-imidazolinone(HBI)that span a wide range of viscosity sensitivity.Combined with the AggTag method that we previously reported,the varying viscosity sensitivity and emission spectra of these probes enabled a dualcolor imaging strategy that detects both protein oligomers and aggregates during the multistep aggregation process of proteins in live cells.In summary,our work indicates that installing intracellular excited state hydrogen bonds to RBFs allows for a rational control of rotational barrier,thus allow for a fine tune of their viscosity sensitivity.Beyond RBFs,we envision similar strategies can be applied to control the fluorogenic behavior of a large group of fluorophores whose emission is dependent on excited state rotational motion,including aggregation-induced emission fluorophores.

Recent advances on small-molecule fluorophores with emission beyond 1000 nm for better molecular imaging in vivo

In the second near-infrared channel(NIR-II, 1000–1700 nm), organic and inorganic fluorophores are designed with superior chemical/optical properties to provide real-time information with deeper penetration depth and higher resolution owing to the innate lower light scattering and absorption of the NIR-II imaging than conventional optical imaging. Among them, the small-molecule based fluorophores have been highlighted due to their desirable biocompatibility and favorable pharmacokinetics. In this review, we introduced the latest research progress of the rational design of small-molecule NIR-II fluorophores and their impressively biological applications including the NIR-II signal imaging,multimodal imaging and theranostic.

Building multipurpose nano-toolkit by rationally decorating NIR-Ⅱ fluorophore to meet the needs of tumor diagnosis and treatment

Phototheranostics have attracted tremendous attention in cancer diagnosis and treatment because of the noninvasiveness and promising effectiveness.Developing advanced phototheranostic agents with long emission wavelength,excellent biocompatibility,great tumor-targeting capability,and efficient therapeutic effect is highly desirable.However,the mutual constraint between imaging and therapeutic functions usually hinders their wide applications in biomedical field.To balance this contradiction,we herein rationally designed and synthesized three novel tumor-targeted NIR-Ⅱ probes(QR-2PEG_(321),QR-2PEG_(1000),and QR-2PEG_(5000)) by conjugating three different chain lengths of PEG onto an integrin α_(v)β_(3)-targeted NIR-Ⅱ heptamethine cyanine fluorophore,respectively.In virtue of the essential amphiphilic characteristics of PEG polymers,these probes display various degree of aggregation in aqueous buffer accompanying with differential NIR-Ⅱ imaging and photothermal(PTT) therapeutic performance.Both in vitro and in vivo results have demonstrated that probe QR-2PEG_(5000) has the best NIR-Ⅱ imaging performance with prominent renal clearance,whereas QR-2PEG_(321)possesses excellent photoacoustic signal as well as PTT effect,which undoubtedly provides a promising toolbox for tumor diagnosis and therapy.We thus envision that these synthesized probes have great potential to be explored as a toolkit for precise diagnosis and treatment of malignant tumors.

New guidelines for fluorophore application in peroxisome targeting analyses in transient plant expression systems

Peroxisome research has been revolutionized by proteome studies combined with in vivo subcellular targeting analyses. Yellow and cyan fluorescent protein(YFP and CFP) are the classical fluorophores of plant peroxisome research. In the new transient expression system of Arabidopsis seedlings co-cultivated with Agrobacterium we detected the YFP fusion of one candidate protein in peroxisomes, but only upon co-transformation with the peroxisome marker, CFP-PTS1. The data suggested that the YFP fusion was directed to peroxisomes due to its weak heterodimerization ability with CFP-PTS1,allowing piggy-back import into peroxisomes. Indeed, if co-expressed with monomeric Cerulean-PTS1(mCer-PTS1),the YFP fusion was no longer matrix localized. We systematically investigated the occurrence and extent of dimerization-based piggy-back import for different fluorophore combinations in five major transient plant expression systems. In Arabidopsis seedlings and tobacco leaves both untagged YFP and monomeric Venus were imported into peroxisomes if co-expressed with CFP-PTS1 but not with mCer-PTS1. By contrast, piggy-back import of cytosolic proteins was not observed in Arabidopsis and tobacco protoplasts or in onion epidermal cells for any fluorophore combination at any time point. Based on these important results we formulate new guidelines for fluorophore usage and experimental design to guarantee reliable identification of novel plant peroxisomal proteins.

NIR-Ⅱ Fluorophores:From Synthesis to Biological Applications

Fluorescence imaging is a useful tool in the field of biomedical applications.However,its imaging capacity is limited by the depth of tissue that can be penetrated when using visible light(400-700 nm)or the first near-infrared window(NIR-Ⅰ,700-900 nm).To overcome the problem,fluorescence imaging in the second near-infrared window(NIR-Ⅱ,1000-1700 nm)has been developed to reduce photon scattering,auto-absorption and tissue autofluorescence to achieve high spatiotemporal resolution and deep imaging penetration.The key to NIR-Ⅱimaging is obtaining and analyzing highly selective information from functional fluorophores that emit in the 1000-1700 nm range.With the rapid development of multidisciplinary research,various types of NIR-Ⅱfluorophores have been produced and used in non-invasive,real-time NIR-Ⅱbiomedical applications.This review summarizes some of the most prevalent NIR-Ⅱfluorophores and their synthesis,such as organic fluorophores(OFs),single-walled carbon nanotubes(SWCNTs),quantum dots(QDs),and rare-earth nanoparticles(RENPs).On this basis,we describe the applications of these fluorophores in biomedical fields,including bioimaging,biosensing,phototherapy and surgical navigation.Additionally,major challenges and prospects of NIR-Ⅱbiomedical application will be further explored.

Small Molecular NIR-II Fluorophores for Cancer Phototheranostics

Phototheranostics integrates deep-tissue imaging with phototherapy(containing photothermal therapy and photodynamic therapy),holding great promise in early diagnosis and precision treatment of cancers.Recently,second near-infrared(NIR-II)fluorescence imaging exhibits the merits of high accuracy and specificity,as well as real-time detection.Among the NIR-II fluorophores,organic small molecular fluorophores have shown superior properties in the biocompatibility,variable structure,and tunable emission wavelength than the inorganic NIR-II materials.What’s more,some small molecular fluorophores also display excellent cytotoxicity when illuminated with the NIR laser.This review summarizes the progress of small molecular NIR-II fluorophores with different central cores for cancer phototheranostics in the past few years,focusing on the molecular structures and phototheranostic performances.Furthermore,challenges and prospects of future development toward clinical translation are discussed.

A dsDNA-lighted fluorophore for monitoring protein-ligand interaction through binding-mediated DNA protection

Because of their important roles in cellular functions, life activities, drug screening, and disease treatment, the development of efficient methods for monitoring protein-ligand interaction is essential. In this study, inspired by our previous studies on DNA conformation-selective fluorescent indicators, we developed a new sensing platform for monitoring protein-ligand interaction and detecting protein activity based on binding-mediated DNA protection and the dsDNA-lighted fluorophore, ethyl-4-[3,6-bis(1-methyl-4-vinylpyridium iodine)-9 H-carbazol-9-yl)] butanoate(EBCB). The ligand was purposefully linked to the 3?-terminal of a hairpin DNA probe to selectively bind with the target protein and protect the DNA from cleavage by exonuclease III. By virtue of EBCB's outstanding capacity to discriminate DNA conformation, the protein-ligand interaction could be effectively monitored through a fluorescence change in EBCB. A high fluorescence signal was detected when the hairpin DNA was protected in the presence of the target protein, whereas a much lower signal was observed in the presence of nontarget proteins.Our results demonstrated that the proposed strategy had high potential, such as high selectivity and relatively high sensitivity, for monitoring protein-ligand interaction and detecting protein activity. We believe these results will pave the way for applying dsDNA-lighted fluorophore EBCB as an effective signal transducer for DNA conformation transformation-mediated biochemical sensing.

An amphiphilic molecule with a single fluorophore exhibits multiple stimuli-responsive behavior

Fluorescent materials that respond to multiple stimuli have broad applications ranging from sensing and bioimaging to information encryption.Herein,we report the design and synthesis of a single-fluorophorebased amphiphile DCSO,which shows temperature-,solvent-,humidity-,and radiation-dependent fluorescence.DCSO consists of a dicyanostilbene(DCS)group as a rigid hydrophobic core with oligo(ethylene glycol)(OEG)chains at both ends as a flexible hydrophilic periphery.The DCS group acts as a highly efficient fluorophore,while the OEG chain endows the molecule with thermo-responsiveness.Fluorescent colors can vary from blue to green to yellow in response to external stimuli.On the basis of light radiation,we demonstrate that this system can be applied to time-dependent information encryption,in which the correct information can only be read at a specific time under irradiation.This work further demonstrates the usefulness and application of single-fluorophore-based luminescent materials with multiple stimuli-responsive functions.

Fluorescent antibiotics for real-time tracking of pathogenic bacteria

The harm of pathogenic bacteria to humans has promoted extensive research on physiological processes of pathogens,such as the mechanism of bacterial infection,antibiotic mode of action,and bacterial antimicrobial resistance.Most of these processes can be better investigated by timely tracking of fluorophore-derived antibiotics in living cells.In this paper,we will review the recent development of fluorescent antibiotics featuring the conjugation with various fluorophores,and focus on their applications in fluorescent imaging and real-time detection for various physiological processes of bacteria in vivo.

Fluorescence guided intraluminal endoscopy in the gastrointestinal tract: A systematic review

BACKGROUND Conventional endoscopy is based on full spectrum white light.However,different studies have investigated the use of fluorescence based endoscopy systems where the white light has been supplemented by infrared light and the use of relevant fluorophores.Fluorescence endoscopy utilizes the fluorescence emitted from a fluorophore,visualizing what is not visible to the naked eye.AIM To explore the feasibility of fluorescence endoscopy and evaluate its use in diagnosing and evaluating gastrointestinal disease.METHODS We followed the PRISMA guidelines for this systematic review.The research covered five databases;PubMed,Scopus,Web of Science,Embase,and the Cochrane Collection,including only studies in English and Scandinavian languages.Authors screened title and abstract for inclusion,subsequently full-text for inclusion according to eligibility criteria listed in the protocol.The risk of bias was assessed for all studies according to the Newcastle-Ottawa Scale.The authors extracted the data and reported the results in both text and tables.RESULTS We included seven studies in the systematic review after screening a total of 2769 papers.The most prominent fluorophore was indocyanine green(n=6),and whereas one study(n=1)used Bevacizumab 800-CW.Three studies investigated fluorescence endoscopy in detecting varices,adenomas in patients with familial adenomatous polyposis and neoplasms in the gastrointestinal tract.Four studies evaluated the usefulness of fluorescence endoscopy in assessing tumor invasion.Three of the four studies reported an exceptional diagnostic accuracy(93%,89%and 88%)in assessing tumor invasion,thus representing better visualization and more correct diagnosis by fluorescence endoscopy compared with the conventional endoscopy.The relationship between the endoscopic findings,tumor invasion,and tumor vascularity was evaluated in two studies showing a significant correlation(dP<0.05 and bP<0.01).CONCLUSION The use of fluorescence endoscopy is a promising method adding diagnostic value in the detection of neoplasia,adenomas,and assessment of tumor invasion within the gastrointestinal tract.More studies are needed to utilize the feasibility of fluorescence endoscopy compared with other endoscopic methods.

Laser Induced Fluorescence Studies of Blood Plasma and Tumor Tissue of Men with Prostate Tumors

Objectives: Fluorescence spectroscopy which can be used for optical tissue diagnosis of tumor pathology?deserves special interest. The purpose of the work was to study blood plasma and tumor tissue of men with different forms of prostate tumors by using laser induced fluorescence. Blood plasma and tumor tissue of the patients with benign hyperplasia of the prostate (BHP), BHP with inflammation, BHP with high grade PIN (BHP with HGPIN) and adenocarcinoma of prostate (CaP) have been studied. Results: In case of blood plasma fluorescence,?intensity of the plasma proteins corresponding peak (340 - 360 nm) was increasing in the following manner: control group → BHP → BHP with HGPIN → CaP. The intensity of the nicotinamide coenzymes correspond peak (440 - 460 nm) was increased in case of BHP with HGPIN and CaP patients, but decreased in case of BHP, compared to control. In case of tumor tissue, the changes of the collagen peak (390 - 400 nm) intensity have been revealed in all cases of prostate tumor tissues. These alterations point to altered collagen biosynthesis levels in different tumor tissues, that reflects the structural changes and characteristics of malignant transformation. Also the changes of the nicotinamide coenzymes peak (440 - 460 nm) intensity in all spectra of tumor tissues were observed. The highest intensity of the peak was observed in the spectra of BHP with HGPIN and in prostate cancer tissue. Conclusions: Alterations of the coenzymes peak intensities perfectly reflect and are in accordance with the specific energy metabolism of prostate epithelial cells. Normalization of fluorescent spectra from different forms of prostate tumor tissues has shown that, each form has typical spectral shape and ratio of fluorescence peaks intensities.

Thiomethyl Derivatives of Two Oligo(p-phenylene vinylenes) as New Aggregation-Induced Piezofluorochromic Emitters

Two piezochromic fluorescent compounds are prepared by introducing thiomethyl substituents to the peripheralpositions of two related cyano oligo(p-phenylene vinylenes) (CN-OPV). The new derivatives, namely, 1,4-bis[2-cyano-2(4-thiomethylphenyl)ethenyl]benzene (TOPV1) and 1,4-bis(1-cyano-2-(4-thiomethylphenyl)ethenyl) benzene (TOPV2), are characterized by NMR, powder X-ray diffraction data (XRD) and differential scanning calorimetric (DSC) data. UV-Vis and fluorescence spectra are also measured. TOPV1 with the cyano groups farther away from the central aromatic ring is photoluminescent, and on application of pressure exhibits a more obvious color change and higher Stokes shift than those measured for TOPV2. We also observe piezochromic aggregation-induced emission (PAIE) for TOPV2, but TOPV1 does not exhibit any PAIE.

Spectroscopic Study of the Interactionbetween New Fluorescent Dyes with Nucleic Acids

A series of new dansylamide derivatives have been synthesized and the specific bindingaffinity of such fluorophores to nucleic acids has been investigated by using absorption, circulardichroism (CD), fluorescence and atomic force microscopy (AFM). The results indicate that thepositive charge of the ligand and the stacking between the dansy1 part of the ligand and theDNA base pair may play an important role when binding to polynucleotides.

An acidic medium-compatible deep-near-infrared dye for in vivo imaging

In vivo imaging in the deep near-infrared(NIR)spectral region,that is,beyond 800 nm,has become popular due to its penetration depth.While imaging of the neutral medium/tissue has been repeatedly showcased,imaging of the high-acidic medium remains challenging partly because of the high-lying HOMO orbital and hence a high pKa of the electron-donating group of the NIR fluorophores.We devised a novel electron-donating group(D6)with which we further synthesized ECJ.ECJ exhibits an absorption wavelength beyond 900 nm and is fluorescent.Its pKa was found to be lower than zero,rendering it suitable for bioimaging of a highly-acidic medium.Its potential for practical applications was showcased in proof-of-concept in vivo imaging with a mouse model.