Near Infrared Dyes as Lifetime Solvatochromic Probes for Micropolarity Measurements of Biological Systems

Berezin, Mikhail Y.; Lee, Hyeran; Akers, Walter J.; Achilefu, Samuel

doi:10.1529/biophysj.107.111609

Cited by 154 publications

(168 citation statements)

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“…Imaging of NIR fluo- rophores expands the available spectrum for MPM, minimizes autofluorescence, and may potentially improve penetration depth. This simple and affordable turnkey fiber-based laser system could serve as a platform for characterizing and imaging other NIR fluorophores 14,15 near 1550 nm. While 2P excitation spectra do not consistently mirror the 1P absorption spectra, 2 in many cases the 2P excitation peak is at or near twice the wavelength of the 1P peak.…”

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confidence: 99%

Multiphoton microscopy with near infrared contrast agents

et al. 2010

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Abstract. While multiphoton microscopy ͑MPM͒ has been performed with a wide range of excitation wavelengths, fluorescence emission has been limited to the visible spectrum. We introduce a paradigm for MPM of near-infrared ͑NIR͒ fluorescent molecular probes via nonlinear excitation at 1550 nm. This all-NIR system expands the range of available MPM fluorophores, virtually eliminates background autofluorescence, and allows for use of fiber-based, turnkey ultrafast lasers developed for telecommunications. Multiphoton microscopy ͑MPM͒ has become an indispensable optical imaging modality due to its intrinsic threedimensional localization, low photobleaching and photodamage outside the focal volume, and improved imaging depth. 1MPM typically uses near-infrared ͑NIR͒ excitation at 700 to 1000 nm to generate fluorescence in the visible wavelengths.2 Although the excitation wavelength of MPM has been extended 3-8 beyond 1000 nm, to our knowledge no imaging has been performed with NIR-emitting contrast agents. Conventional ͑linear͒ fluorescence imaging has shown that molecular imaging with NIR ͑ Ͼ 700 nm͒ agents minimizes the contribution from endogenous fluorescence and increases penetration depth.9 Since conventional MPM efficiently images endogenous molecules such as collagen, elastin, and reduced nicotinamide adenine dinucleotide ͑NADH͒, 10 the signal from these and other endogenous fluorophores restricts molecular imaging with exogenous contrast agents. This is particularly problematic when target concentrations are low, and strategies to reduce autofluorescence become critical to image contrast. Here, we measure twophoton-induced fluorescence of NIR dyes and demonstrate their use for autofluorescence-free biological imaging.Heptamethine cyanine dyes were selected as NIR contrast agents because of their biocompatibility and the availability of diverse structures with single photon ͑1P͒ absorption and emission between 700 and 850 nm. Cypate, a derivative of indocyanine green, was prepared as previously reported, 11 and 3,3Ј-diethylthiatricarbocyanine iodide ͑DTTCI͒ were purchased from a commercial source ͑Sigma-Aldrich, Saint Louis, Missouri͒. These dyes exhibit an absorption/emission peak of 799/ 817 nm and 771/ 800 nm, respectively. Fortuitously, these absorption maxima of NIR dyes correspond to roughly half the telecommunications spectral window at 1550 nm. As this overlaps with the gain spectrum of erbium, we perform all-NIR MPM using a simple, turnkey erbiumdoped fiber laser. A mode-locked femtosecond fiber laser ͑Mercury 1000, PolarOnyx, Sunnyvale, California͒ provided 100 mW of excitation light at ϳ1550 nm through a ϳ1-m optical fiber ͑Fig. 1͒. At the output of the fiber, the pulse duration was nominally 100 fs with a repetition rate of 50 MHz, although positive material dispersion of the optical components in the system leads to pulse broadening and reduces excitation efficiency at the sample. These losses can be recovered if the pulses arriving at the sample are transformlimited by precompensating for material...

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Multiphoton microscopy with near infrared contrast agents

et al. 2010

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“…The sensitivity of the proposed imaging system was tested by recording the NIR fluorescent signal responses for different ICG concentrations and different LS301 18,22,23 concentrations dissolved in 100% dimethyl sulfoxide (DMSO). ICG has been widely used for NIR fluorescence since its FDA approval in the late 1960s.…”

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Image overlay solution based on threshold detection for a compact near infrared fluorescence goggle system

et al. 2015

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Abstract. Near infrared (NIR) fluorescence imaging has shown great potential for various clinical procedures, including intraoperative image guidance. However, existing NIR fluorescence imaging systems either have a large footprint or are handheld, which limits their usage in intraoperative applications. We present a compact NIR fluorescence imaging system (NFIS) with an image overlay solution based on threshold detection, which can be easily integrated with a goggle display system for intraoperative guidance. The proposed NFIS achieves compactness, light weight, hands-free operation, high-precision superimposition, and a real-time frame rate. In addition, the miniature and ultra-lightweight light-emitting diode tracking pod is easy to incorporate with NIR fluorescence imaging. Based on experimental evaluation, the proposed NFIS solution has a lower detection limit of 25 nM of indocyanine green at 27 fps and realizes a highly precise image overlay of NIR and visible images of mice in vivo. The overlay error is limited within a 2-mm scale at a 65-cm working distance, which is highly reliable for clinical study and surgical use.

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“…The OD measurement gives light attenuation after traveling in the solution of the compound depending on the product of ε; c, and l. In our measurements, cells with thickness of 1 cm are used. Since, the molar extinction coefficient of certain compounds such as ICG, cypate 3, or cypate can be found from the previous study [13], the concentration can be obtained using the results of the OD measurements and Eq. (1).…”

Section: B Absorption and Fluorescence Spectra Of Cypate 3 And Cypatmentioning

confidence: 99%

Synthesis of dye conjugates to visualize the cancer cells using fluorescence microscopy

Tang

Xue

et al. 2014

Appl. Opt.

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The clinical diagnosis of most cancers is based on evaluation of histology microscopic slides to view the size and shape of cellular nuclei and morphological structure of tissue. To achieve this goal for in vivo and in-deep tissues, near infrared dyes-bovine serum albumin and immunoglobulin G conjugates were synthesized. The spectral study shows that the absorption and fluorescence of the dye conjugates are in the "tissue optical window" spectral ranges between 650 and 900 nm. The internalization and pinocytosis of the synthesized compounds were investigated at cell level using fluorescence microscopy to obtain the optimal concentration and staining time.

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Near Infrared Dyes as Lifetime Solvatochromic Probes for Micropolarity Measurements of Biological Systems

Cited by 154 publications

References 40 publications

Multiphoton microscopy with near infrared contrast agents

Multiphoton microscopy with near infrared contrast agents

Image overlay solution based on threshold detection for a compact near infrared fluorescence goggle system

Synthesis of dye conjugates to visualize the cancer cells using fluorescence microscopy

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