Project description:Near-IR fluorescence imaging has great potential for noninvasive in vivo imaging of tumors. In this study, we show the preferential uptake and retention of two hepatamethine cyanine dyes, IR-783 and MHI-148, in tumor cells and tissues.IR-783 and MHI-148 were investigated for their ability to accumulate in human cancer cells, tumor xenografts, and spontaneous mouse tumors in transgenic animals. Time- and concentration-dependent dye uptake and retention in normal and cancer cells and tissues were compared, and subcellular localization of the dyes and mechanisms of the dye uptake and retention in tumor cells were evaluated using organelle-specific tracking dyes and bromosulfophthalein, a competitive inhibitor of organic anion transporting peptides. These dyes were used to detect human cancer metastases in a mouse model and differentiate cancer cells from normal cells in blood.These near-IR hepatamethine cyanine dyes were retained in cancer cells but not normal cells, in tumor xenografts, and in spontaneous tumors in transgenic mice. They can be used to detect cancer metastasis and cancer cells in blood with a high degree of sensitivity. The dyes were found to concentrate in the mitochondria and lysosomes of cancer cells, probably through organic anion transporting peptides, because the dye uptake and retention in cancer cells can be blocked completely by bromosulfophthalein. These dyes, when injected to mice, did not cause systemic toxicity.These two heptamethine cyanine dyes are promising imaging agents for human cancers and can be further exploited to improve cancer detection, prognosis, and treatment.
Project description:A novel anionic heptamethine cyanine (HMC) dye with two trifluoromethyl groups that selectively absorb near-infrared light is synthesized. When contrasted with previously studied anionic HMC dyes with substituents such as methyl, phenyl, and pentafluorophenyl groups, the trifluoromethylated dye displays a red-shifted maximum absorption wavelength (for instance, 948 nm in CH2Cl2) along with enhanced photostability. Furthermore, HMC dyes with broad absorption in the near-infrared region are synthesized by combining a trifluoromethylated anionic HMC dye with a cationic HMC dye as a counterion.
Project description:Two new classes of near-infrared molecular probes were prepared and shown to exhibit "turn on" fluorescence when cleaved by the nitroreductase enzyme, a well-known biomarker of cell hypoxia. The fluorescent probes are heptamethine cyanine dyes with a central 4'-carboxylic ester group on the heptamethine chain that is converted by a self-immolative fragmentation mechanism to a 4'-caboxylate group that greatly enhances the fluorescence brightness. Each compound was prepared by ring opening of a Zincke salt. The chemical structures have either terminal benzoindolinenes or propargyloxy auxochromes, which provide favorable red-shifted absorption/emission wavelengths and a hyperchromic effect that enhances the photon output when excited by 808 nm light. A fluorescent probe with terminal propargyloxy-indolenines exhibited less self-aggregation and was rapidly activated by nitroreductase with large "turn on" fluorescence; thus, it is the preferred choice for translation towards in vivo applications.
Project description:We have synthesized and characterized a library of near-infrared (NIR) heptamethine cyanine dyes for biomedical application as photoacoustic imaging and photothermal agents. These hydrophobic dyes were incorporated into a polymer-based nanoparticle system to provide aqueous solubility and protection of the photophysical properties of each dye scaffold. Among those heptamethine cyanine dyes analyzed, 13 compounds within the nontoxic polymeric nanoparticles have been selected to exemplify structural relationships in terms of photostability, photoacoustic imaging, and photothermal behavior within the NIR (∼650-850 nm) spectral region. The most contributing structural features observed in our dye design include hydrophobicity, rotatable bonds, heavy atom effects, and stability of the central cyclohexene ring within the dye core. The NIR agents developed within this project serve to elicit a structure-function relationship with emphasis on their photoacoustic and photothermal characteristics aiming at producing customizable NIR photoacoustic and photothermal tools for clinical use.
Project description:Previous work has shown that the sterically shielded near-infrared (NIR) fluorescent heptamethine cyanine dye, s775z, with a reactive carboxyl group produces fluorescent bioconjugates with an unsurpassed combination of high photostability and fluorescence brightness. This present contribution reports two new reactive homologues of s775z with either a maleimide group for reaction with a thiol or a strained alkyne group for reaction with an azide. Three cancer-targeting NIR fluorescent probes were synthesized, each with an appended cRGDfK peptide to provide selective affinity for integrin receptors that are overexpressed on the surface of many cancer cells including the A549 lung adenocarcinoma cells used in this study. A set of cancer cell microscopy and mouse tumor imaging experiments showed that all three probes were very effective at targeting cancer cells and tumors; however, the change in the linker structure produced a statistically significant difference in some aspects of the mouse biodistribution. The mouse studies included a mock surgical procedure that excised the subcutaneous tumors. A paired-agent fluorescence imaging experiment co-injected a binary mixture of targeted probe with 850 nm emission, an untargeted probe with 710 nm emission and determined the targeted probe's binding potential in the tumor tissue. A comparison of pixelated maps of binding potential for each excised tumor indicated a tumor-to-tumor variation of integrin expression levels, and a heterogeneous spatial distribution of integrin receptors within each tumor.
Project description:The near-infrared window of fluorescent heptamethine cyanine dyes greatly facilitates biological imaging because there is deep penetration of the light and negligible background fluorescence. However, dye instability, aggregation, and poor pharmacokinetics are current drawbacks that limit performance and the scope of possible applications. All these limitations are simultaneously overcome with a new molecular design strategy that produces a charge balanced and sterically shielded fluorochrome. The key design feature is a meso-aryl group that simultaneously projects two shielding arms directly over each face of a linear heptamethine polyene. Cell and mouse imaging experiments compared a shielded heptamethine cyanine dye (and several peptide and antibody bioconjugates) to benchmark heptamethine dyes and found that the shielded systems possess an unsurpassed combination of photophysical, physiochemical, and biodistribution properties that greatly enhance bioimaging performance.
Project description:Heptamethine cyanine dyes are a class of near infrared fluorescence (NIRF) probes of great interest in bioanalytical and imaging applications due to their modifiability, allowing them to be tailored for particular applications. Generally, modifications at the meso-position of these dyes are achieved through Suzuki-Miyaura C-C coupling and SRN1 nucleophilic substitution of the chlorine atom at the meso-position of the dye. Herein, a series of 15 meso phenyl-substituted heptamethine cyanines was synthesized utilizing a modified dianil linker. Their optical properties, including molar absorptivity, fluorescence, Stokes shift, and quantum yield were measured. The HSA binding affinities of two representative compounds were measured and compared to that of a series of trimethine cyanines previously synthesized by our lab. The results indicate that the binding of these compounds to HSA is not only dependent on hydrophobicity, but may also be dependent on steric interferences in the binding site and structural dynamics of the NIRF compounds.
Project description:Organic photodetectors are interesting for low cost, large area optical sensing applications. Combining organic semiconductors with discrete absorption bands outside the visible wavelength range with transparent and conductive electrodes allows for the fabrication of visibly transparent photodetectors. Visibly transparent photodetectors can have far reaching impact in a number of areas including smart displays, window-integrated electronic circuits and sensors. Here, we demonstrate a near-infrared sensitive, visibly transparent organic photodetector with a very high average visible transmittance of 68.9%. The transmitted light of the photodetector under solar irradiation exhibits excellent transparency colour perception and rendering capabilities. At a wavelength of 850 nm and at -1 V bias, the photoconversion efficiency is 17% and the specific detectivity is 10(12) Jones. Large area photodetectors with an area of 1.6 cm(2) are demonstrated.
Project description:Near-infrared fluorescence (NIRF) dyes have recently emerged as promising tools for non-invasive imaging of different types of cancers. Here, we explored the potential utility of a NIRF DZ-1 dye, with dual imaging and tumour targeting functions, in hepatocellular carcinoma (HCC). We showed the preferential uptake of DZ-1 by HCC cells in vitro and in derived subcutaneous/orthotopic tumour xenografts, accompanied by a minimal effect on normal cells. DZ-1 simplified tumour growth profiling as well, since we were able to correlate NIRF signals with tumour volume and/or tumour-emitting luminescence in mice. Using both orthotopic tumour transplantation and cirrhosis models in parallel, we demonstrated the ability of DZ-1 to differentiate liver tumour from cirrhosis. DZ-1 showed superiority in HCC imaging over indocyanine green by demonstrating significantly enhanced tumour-targeting specificity. At the cellular level, DZ-1 was mainly retained in mitochondria and lysosomes. Additionally, DZ-1 fluorescence spectroscopy has been used for the intraoperative navigation of rabbit liver cancer, to determine surgical margins. We showed that tumor hypoxia and select organic anion-transporting polypeptide genes mediate NIRF dye uptake in HCC, which was supported by clinical evidence. All these findings represent the first evidence that DZ-1 is an effective molecular probe for tumour-specific imaging in HCC, and provide insights into the development of a new generation of imaging agents for intraoperative guidance of cancer surgery.
Project description:Continued advancement in bioresponsive fluorescence imaging requires new classes of activatable fluorescent probes that emit near-infrared fluorescence with wavelengths above 740 nm. Heptamethine cyanine dyes (Cy7) have suitable fluorescence properties but it is challenging to create activatable probes because Cy7 dyes have a propensity for self-aggregation and fluorescence quenching. A new synthetic strategy is employed to create a generalizable class of hydrophilic bioresponsive near-infrared fluorescent probes with appended sulfonates that provide excellent physiochemical properties. A prototype version is triggered by nitroreductase enzyme to undergo self-immolative cleavage with a large enhancement in fluorescence signal at 780 nm and the probe enables microscopic imaging of cell hypoxia with "turn on" fluorescence. Near-infrared fluorescence imaging of hypoxia is potentially useful in many different areas of biomedical research and clinical treatment.