Indocyanine Green Absorption Research Articles

Indocyanine Green (ICG) Fluorescence Is Dependent on Monomer with Planar and Twisted Structures and Inhibited by H-Aggregation.

The optical properties of indocyanine green (ICG) as a near-infrared (NIR) fluorescence dye depend on the nature of the solvent medium and the dye concentration. In the ICG absorption spectra of water, at high concentrations, there were absorption maxima at 700 nm, implying H-aggregates. With ICG dilution, the main absorption peak was at 780 nm, implying monomers. However, in ethanol, the absorption maximum was 780 nm, and the shapes of the absorption spectra were identical regardless of the ICG concentration, indicating that ICG in ethanol exists only as a monomer without H-aggregates. We found that emission was due to the monomer form and decreased with H-aggregate formation. In the fluorescence spectra, the 820 nm emission band was dominant at low concentrations, whereas at high concentrations, we found that the emission peaks were converted to 880 nm, suggesting a new form via the twisted intramolecular charge transfer (TICT) process of ICG. The NIR fluorescence intensity of ICG in ethanol was approximately 12- and 9-times brighter than in water in the NIR-I and -II regions, respectively. We propose an energy diagram of ICG to describe absorptive and emissive transitions through the ICG structures such as the monomer, H-aggregated, and TICT monomer forms.

Activatable Lanthanide Nanoprobes with Dye-Sensitized Second Near-Infrared Luminescence for in Vivo Inflammation Imaging.

Lanthanide nanoparticles exhibit unique photophysical properties and thus emerge as promising second near-infrared (NIR-II) optical agents. However, the limited luminescence brightness hampers their construction of activatable NIR-II probes. Herein, we report the synthesis of dye-sensitized lanthanide nanoprobes (NaGdF4:Nd/ICG; indocyanine green (ICG)) and their further development for in vivo activatable imaging of hypochlorite (ClO-). Dye sensitization using ICG not only shifts the optimal doping concentration of Nd3+ from 5 to 20 mol % but also leads to a 5-fold NIR-II enhancement relative to the ICG-free counterpart. Mechanistic studies reveal that such a luminescence enhancement of NaGdF4:Nd at high Nd3+ concentration is ascribed to an alleviated cross-relaxation effect due to the broad absorption of ICG and faster energy transfer process. Taking advantage of dye oxidation, the nanoprobes enable activatable NIR-II imaging of hypochlorous acid (ClO-) in a drug-induced lymphatic inflammation mouse model. This work thus provides a simple, yet effective luminescence enhancement strategy for constructing lanthanide nanoprobes at higher activator doping concentration toward activatable NIR-II molecular imaging.

Fluorescence-guided colorectal surgery: applications, clinical results, and protocols.

In recent years, the rise of minimally invasive surgery has driven the development of surgical devices. Indocyanine green (ICG) fluorescence imaging is receiving increased attention in colorectal surgery for improved intraoperative visualization and decision-making. ICG, approved by the U.S. Food and Drug Administration in 1959, rapidly binds to plasma proteins and is primarily intravascular. ICG absorption of near-infrared light (750-800 nm) and emission as fluorescence (830 nm) when bound to tissue proteins enhances deep tissue visualization. Applications include assessing anastomotic perfusion, identifying sentinel lymph nodes, and detecting colorectal cancer metastasis. However, standardized protocols and research on clinical outcomes remain limited. This study explores ICG's role, advantages, disadvantages, and potential clinical impact in colorectal surgery.

Application of a wavelength-swept laser for spectrally resolved wide-field near-infrared fluorescence imaging

We propose the proof-of-concept of a novel method for wide-field spectrally resolved near-infrared fluorescence (NIRF) imaging using a wavelength-swept laser. The performance of our method is evaluated on a biotissue-like phantom bearing two inclusions, one filled with indocyanine green (ICG) dissolved in distilled water and the second one in dimethyl sulfoxide (DMSO). A near-infrared wavelength-swept laser covering wavelengths around the peak absorption of ICG was used. The difference in the absorption spectra of these two ICG solutions gives rise to an additional spectral contrast. The distinction between the emitted fluorescence light from the two different solutions is performed using a principal component analysis (PCA)-based method. Results show that the two different ICG solutions were successfully resolved using this approach. This technique can be a powerful method to simultaneously spatio-spectrally image multiple near-infrared fluorescence agents.

Biomimetic Nanoreactor for Cancer Eradication via Win–Win Cooperation between Starvation/Photo/Chemodynamic Therapies

Combining phototherapy with the cancer cell metabolic pathway altering strategies, that is, glucose starvation, would be a promising approach to accomplish high curative efficiency of cancer treatment. Accordingly, herein, we sought to construct a multifunctional biomimetic hybrid nanoreactor by fastening nanozyme AuNPs (glucose oxidase activity) and PtNPs (catalase and peroxidase activity) and photosensitizer Indocyanine green (ICG) onto the polydopamine (PDA) surface (ICG/Au/Pt@PDA-PEG) to attain superior cancer cell killing efficiency though win-win cooperation between starvation therapy, phototherapy, and chemodynamic therapy. The as-synthesized ICG/Au/Pt@PDA-PEG has shown excellent light-to-heat conversion (photothermal therapy) and reactive oxygen species generation (photodynamic therapy) properties upon laser irradiation and also red-shifted ICG absorption (from 780 to 800 nm) and enhanced its photostability. Further, the ICG/Au/Pt@PDA-PEG NRs have reduced the solution glucose concentration and slightly increased solution oxygen levels and also enhanced 3,3',5,5'-tetramethylbenzidine oxidation in the presence of glucose through a cascade of enzymatic activities. The in vitro results demonstrated that the ICG/Au/Pt@PDA-PEG NRs have superior therapeutic efficacy against cancer cells via the cooperative effect between starvation/photo/chemodynamic therapies and not much toxicity to normal cells.

Sublingual indocyanine green films for non-invasive swallowing assessment and inflammation detection through NIR/SWIR optical imaging

Indocyanine green (ICG) is the most commonly used FDA-approved agent for clinical optical imaging, administered through injections only, due to its poor membrane permeability. Although ICG has vast potential for non-invasive non-radioactive imaging in patients, the clinical applications are limited by the invasive administration and short half-life in blood circulation. To expand the clinical value of ICG, non-toxic chitosan-based ICG-loaded films were designed for sublingual administration for near-infrared (NIR) and short-wave infrared (SWIR) optical imaging. Two film formulations were developed with different ICG release rates. Mold-casted self-emulsifying films rapidly released ICG (80% in 4 h) in the form of nanosized droplets, which were mostly swallowed and produced significant contrast of upper digestive tract to enable in vivo swallowing evaluations using NIR/SWIR imaging. Regular films released ICG slowly (80% in 25 h), allowing for steady absorption of ICG to systemic circulation. Inflammation in mouse feet was detected within 30 min after sublingual administration with a 1.43-fold fluorescence increase within 1 h at the inflammation sites, comparable to a 1.76-fold increase through intravenous injection. Administering ICG using sublingual films displayed notable potential for non-invasive diagnosis and monitoring of inflammatory conditions and swallowing disorders, addressing a current need for alternatives to ICG parenteral administration.

Optical properties of indocyanine green under ultrasound treatment

Indocyanine green (ICG) is an FDA-approved and commercially available dye that exhibits fluorescence in the near infrared region. ICG has been utilized as a contrast agent for a wide range of applications in biomedical research and clinical diagnostics, particularly in-vivo imaging. The optical properties of ICG are known to be sensitive to its concentration, the temperature, and the presence of different serum proteins in its solutions. In this paper, we report a notable effect on modifying the optical properties of ICG using ultrasound (US) waves. Mid-frequency US waves at different powers were applied to ICG and bovine serum albumin (BSA) dissolved in a phosphate buffered saline (PBS) solution. Our experimental results indicate a significant increase of the absorption and fluorescence of ICG dissolved PBS in the presence of BSA when the applied US is above a threshold pressure (4.4 MPa). In contrast, ICG samples without BSA showed no enhancement effect on ICG's absorption or fluorescence emission after US treatments under the same condition. In addition, the stability of the ICG samples after the US treatments was also measured. Significantly improved stability of ICG samples in the presence of BSA under the US treatment with a pressure higher than 4.4 MPa was observed. The mechanism of the enhancement effects of US on the optical properties of ICG has been discussed in this paper.

Highly Sensitive MoS2\u2013Indocyanine Green Hybrid for Photoacoustic Imaging of Orthotopic Brain Glioma at Deep Site

Photoacoustic technology in combination with molecular imaging is a highly effective method for accurately diagnosing brain glioma. For glioma detection at a deeper site, contrast agents with higher photoacoustic imaging sensitivity are needed. Herein, we report a MoS2–ICG hybrid with indocyanine green (ICG) conjugated to the surface of MoS2 nanosheets. The hybrid significantly enhanced photoacoustic imaging sensitivity compared to MoS2 nanosheets. This conjugation results in remarkably high optical absorbance across a broad near-infrared spectrum, redshifting of the ICG absorption peak and photothermal/photoacoustic conversion efficiency enhancement of ICG. A tumor mass of 3.5 mm beneath the mouse scalp was clearly visualized by using MoS2–ICG as a contrast agent for the in vivo photoacoustic imaging of orthotopic glioma, which is nearly twofold deeper than the tumors imaged in our previous report using MoS2 nanosheet. Thus, combined with its good stability and high biocompatibility, the MoS2–ICG hybrid developed in this study has a great potential for high-efficiency tumor molecular imaging in translational medicine.

Indocyanine green as effective antibody conjugate for intracellular molecular targeted photodynamic therapy.

The fluorescent dye indocyanine green (ICG) is clinically approved and has been applied for ophthalmic and intraoperative angiography, measurement of cardiac output and liver function, or as contrast agent in cancer surgery. Though ICG is known for its photochemical effects, it has played a minor role so far in photodynamic therapy or techniques for targeted protein-inactivation. Here, we investigated ICG as an antibody-conjugate for the selective inactivation of the protein Ki-67 in the nucleus of cells. Conjugates of the Ki-67 antibody TuBB-9 with different amounts of ICG were synthesized and delivered into HeLa and OVCAR-5 cells through conjugation to the nuclear localization sequence. Endosomal escape of the macromolecular antibodies into the cytoplasm was optically triggered by photochemical internalization with the photosensitizer BPD. The second light irradiation at 690 nm inactivated Ki-67 and subsequently caused cell death. Here, we show that ICG as an antibody-conjugate can be an effective photosensitizing agent. Best effects were achieved with 1.8 ICG molecules per antibody. Conjugated to antibodies, the ICG absorption peaks vary proportionally with concentration. The absorption of ICG above 650 nm within the optical window of tissue opens the possibility of selective Ki-67 inactivation deep inside of tissues.

Overexpression of transcription factor Foxa2 and Hnf1α induced rat bone mesenchymal stem cells into hepatocytes.

Hepatocytes differentiated from induced pluripotent stem cells and adult stem cells could be utilized as a tool for the study of liver diseases, screening for drug metabolism and hepatotoxicity. Thus further investigationofthemethod to efficiently generate hepatocytes is in great need. Bone Mesenchymal Stem Cells (BMSCs) were collected from rat femurs and tibias. FOXA2 and HNF1α genes were constructed into a lentiviral vector and introduced into BMSCs by a lentivirus-mediatedoverexpression system. Three weeks after the induction, the expressions of FOXA2 and HNF1α, and liver specific genes were analyzed, and hepatocyte-function related assays were performed. Overexpression of both FOXA2 and HNF1α induced the BMSCs to differentiate into hepatocyte-like cells (HLCs). Hepatocyte-specific gene and protein were detected by RT-PCR, Western Blot and Immunofluorescence. These HLCs also exerted some typical hepatocyte functions such as glycogen storage, indocyanine green absorption and lipid accumulation. The combination of FOXA2 and HNF1α can effectively induce BMSCs to differentiate into HLCs. This is a novel and efficient method to prepare HLCs within a short timeline.

Useful properties of undifferentiated mesenchymal stromal cells and adipose tissue as the source in liver-regenerative therapy studied in an animal model of severe acute fulminant hepatitis

Background aimsEnd-stage liver diseases frequently require liver transplantation. Cell therapy could be an alternative. This study aimed to analyze whether undifferentiated mesenchymal stromal cells (U-MSCs) or MSC-derived hepatocyte-like cells (DHLCs) from adipose tissue (AT), umbilical cord blood (UCB) and bone marrow (BM) would better restore damaged liver. MethodsAT was obtained from lipo-aspiration, UCB from an Umbilical Cord Blood Bank and BM from a BM Transplantation Unit. AT (collagenase digestion), UCB and BM (Ficoll gradient) were cultured (Dulbecco's modified Eagle's medium, low glucose, FBS) for 3 days. Detached adherent cells, at passage 4, were characterized as MSCs. Genetic stability was investigated by means of telomerase enzyme activity and karyotype. Hepatocyte differentiation protocol was performed with the use of Dulbecco's modified Eagle's medium, hepatocyte growth factor, basic fibroblast growth factor and nicotinamide (7 days); maturation medium (oncostatin, dexamethasone, insulin, transferrin and selenium) was added at 36 days. Hepatogenesis analyses were performed by use of morphology and albumin, AF, tyrosine-aminotransferase and glutamine synthetase gene expression and quantitative reverse transcription–polymerase chain reaction on days 9, 18, 25 and 36. Functionality was assessed through glycogen storage detection, indocyanine green absorption and transplantation procedure. U-MSCs and DHLCs were injected 48 h after induced fulminant hepatitis (intraperitoneal injection of carbon tetrachloride) in SCID/BALB-c mice. Histopathologic analyses were performed on days 7 and 15. Human origin included albumin and CK19 human markers. ResultsAll MSCs differentiated into functional hepatocyte-like cells, stored glycogen and absorbed indocyanine green. AT-MSC DHLC gene expression was more consistent with a normal hepatogenic-differentiation profile. UCB-MSCs expanded weakly, impairing their use for the transplantation procedure. AT and BM U-MSCs and DHLCs regenerated liver injury equally. Regenerated hepatocytes exhibited human origin. ConclusionsAT might be the source and U-MSCS the stem cells useful for liver-regenerative therapy.

Induction of Functional Hepatocyte-Like Cells by Overexpression of FOXA3 and HNF4α in Rat Bone Marrow Mesenchymal Stem Cells

Liver regeneration has always been of great therapeutic interest, particularly to generate hepatocytes from other types of cells including adult stem cells and induced pluripotent stem cells. In this study, it was found that overexpression of both FOXA3 and HNF4α can convert rat bone marrow mesenchymal stem cells (BMSCs) to functional hepatocyte-like cells (HLCs). The results show that these HLCs had the typical hepatocyte morphology with unique hepatocyte markers such as ALB, G6P, KRT18, TAT, TTR, KRT19 and AFP. Simultaneously, they also exhibited hepatic functions such as glycogen storage, indocyanine green absorption, and cytoplasmic accumulation of neutral triglycerides and lipids. In addition to that, these functions could be maintained in the process of cell culture, thus suggesting that FOXA3 and HNF4α are powerful transcription factors for inducing rat BMSCs to differentiate into functional HLCs, and this study will provide a novel method to generate HLCs.

Revisiting Indocyanine Green: Effects of Serum and Physiological Temperature on Absorption and Fluorescence Characteristics

Indocyanine green (ICG) remains as the only near infrared dye approved by the FDA. Despite its long history of usage in clinical medicine, a systematic study of the effects of serum proteins at physiologically relevant levels and temperature on absorption and fluorescence characteristics of ICG has been missing. We incubated ICG at concentrations in the range of 0.6-25.8 μM in McCoy's 5a cell culture medium, without and with supplemental fetal bovine serum (FBS) at 5% and 10% levels. Our analyses of absorption and fluorescence spectra indicate that the peak absorbance of ICG associated with its monomeric form increases in the presence of FBS. For example, at ICG concentration of 25.8 μM, the monomer absorbance is increased by nearly 100% in the presence of 10% FBS. Similarly, there is an increase in the relative fluorescence quantum yield of ICG, by as much as nearly 3.5 times in the presence of FBS. When incubated at 37 °C, the presence of FBS in the cell culture medium helps maintain the monomeric absorption of ICG and sustain the increased fluorescence emission. We offer explanations to describe the possible photophysical mechanisms underlying the observed effects and discuss the importance of these results to in-vivo applications of ICG.

结合近红外光谱法的肝血流参数测量

A pulse spectroscopic scheme based on dye dilution and an excretion test was developed to overcome the shortcomings of conventional blood dye concentration measuring method in complex operation,invasive treatment and non-continuance.Firstly,Indocyanine Green(ICG) was intravenously injected and a finger clip sensor was used to extract spectral signals of fingertips for a sufferer.Then,by recording the dye dilution curve simultaneously,the algorithm to isolate ICG absorption spectrum from the disturbance of peripheral arterial blood was implemented.Finally,the ICG plasma disappearance rate K,15 min retention rate R15and other hepatic hemodynamic parameters were deduced by analyzing the semi-logarithmic dye concentration graph.Combining a lab-VIEW software platform with an adaptive differential threshold method,proposed scheme eliminates the interference come from the hemoglobin absorption spectrum and baseline drift,improves the measuring accuracy greatly,and the average measurement error of K is less than 0.008.This method is great value to not only the assessing hepatic functional reserve at pre-operation,intra-operation,post-operation,but also providing a way to monitor some middle variables for clinical research purposes.

The Use of Indocyanine Green Videoangiography to Optimize the Dural Opening for Intracranial Parasagittal Lesions

We describe our clinical experience with the use of indocyanine green (ICG) videoangiography to delineate the locations of the cortical draining veins before dural opening in 3 cases of parasagittal lesions. With this technique, the veins are marked through the dura, and then the dura can be opened precisely to avoid cortical venous injury. To demonstrate in a clinical series the adjunct use of intraoperative ICG angiography to optimize the dural opening for parasagittal lesions. We describe 3 cases of parasagittal lesions, 2 meningiomas, and 1 arteriovenous malformation treated using the described technique. Once the dura had been exposed, ICG at a dose of 0.25 mg/kg was injected into the patient's peripheral vein as a bolus. When the dye reached the illuminated field of interest, ICG fluorescence was induced by the use of a light source with a wave-length ICG absorption band. Thereafter, the dural cortical veins were marked through the dura and precisely opened, avoiding cortical venous injury. Indocyanine green video angiography is a safe, fast, inexpensive, and accurate investigation that allows the surgeon to strategically plan and protect important parasagittal dural venous drainage during craniotomy.

A comparison of transcranial Doppler with near infrared spectroscopy and indocyanine green during hemorrhagic shock: a prospective experimental study

IntroductionThe present study was designed to compare cerebral hemodynamics assessed using the blood flow index (BFI) derived from the kinetics of the tracer dye indocyanine green (ICG) with transcranial Doppler ultrasound (TCD) in an established model of hemorrhagic shock.MethodsAfter approval from the Animal Investigational Committee, 20 healthy pigs underwent a simulated penetrating liver trauma. Following hemodynamic decompensation, all animals received a hypertonic-isooncotic hydroxyethyl starch solution and either arginine vasopressin or norepinephrine, and bleeding was subsequently controlled. ICG passage through the brain was monitored by near infrared spectroscopy. BFI was calculated by dividing maximal ICG absorption change by rise time. Mean blood flow velocity (FVmean) of the right middle cerebral artery was recorded by TCD. FVmean and BFI were assessed at baseline (BL), at hemodynamic decompensation, and repeatedly after control of bleeding.ResultsAt hemodynamic decompensation, cerebral perfusion pressure (CPP), FVmean and BFI dropped compared to BL (mean ± standard deviation; CPP 16 ± 5 mmHg versus 70 ± 16 mmHg; FVmean 4 ± 5 cm·s-1 versus 28 ± 9 cm·s-1; BFI 0.008 ± 0.004 versus 0.02 ± 0.006; p < 0.001). After pharmacological intervention and control of bleeding, FVmean and BFI increased close to baseline values (FVmean 23 ± 9 cm·s-1; BFI 0.02 ± 0.01), respectively. FVmean and BFI were significantly correlated (r = 0.62, p < 0.0001).ConclusionFVmean and BFI both reflected the large variations in cerebral perfusion during hemorrhage and after resuscitation and were significantly correlated. BFI is a promising tool to monitor cerebral hemodynamics at the bedside.

Measurement of Indocyanine Green Dye Concentration in the Extracorporeal Circulation

Indocyanine green (ICG) is a dye used to measure plasma volume and cardiac output and to assess hepatic function by monitoring the ICG plasma disappearance rate. A method for continuous and noninvasive measurement of ICG plasma concentration (c) in the extracorporeal circulation is presented using technology originally developed for on-line measurement of hematocrit. As expected from the ICG absorption maximum at 805 nm, the presence of ICG in blood leads to a pronounced increase in hematocrit (Hct) measured by optical means. This apparent change in hematocrit (Hct(rel) = Hct/ Hct(b) - 1) relative to the baseline hematocrit (Hct(b), where c = 0) showed a strong linear relationship (Hct(rel) = k.c) with respect to ICG concentration. The dependence of k on baseline hematocrit was best described by an exponential relationship (k = a*e(b*Hctb)). The constants a and b were determined in in vitro experiments using bovine blood. With the information on a and b, and when baseline hematocrit is known and can be assumed to remain constant throughout the observation phase, plasma ICG concentration can be noninvasively and continuously measured in the extracorporeal circulation by using available optical techniques without taking blood samples. This approach greatly simplifies the diagnostic use of ICG, which may be of importance in patients treated with extracorporeal blood purification techniques.

Noninvasive cerebral optical spectroscopy: depth-resolved measurements of cerebral haemodynamics using indocyanine green.

To investigate the feasibility of a newly developed, near-infrared optical spectroscopy device, we analysed measurements of the infrared tracer indocyanine green (ICG) using sensors with a single near infrared light source and multiple light detectors. Two ml of ICG dye, 1.0 mg ml-1 in concentration, were injected into the internal carotid artery during cerebral angiography in 14 adult patients. The resultant washout curves were measured bilaterally using sensors with 4 detectors spaced at 10, 20, 30 and 40 mm from the infrared light source on the right side, and 15, 25, 35 and 45 mm from the source for the left side, respectively. Washout curves were analysed to determine the relative amplitude of the ICG absorption signal and deduce each detector's penetration distance. When ICG was injected into the internal carotid artery, relative absorption increased with detector distance from the light source. No substantial difference in attenuation was observed in any of the detectors during external carotid injection of ICG. The resultant information related depth of penetration of the light with source-detector separation distances. The feasibility of the system for measuring cerebral oxygen saturation and haemodynamics noninvasively or monitoring at bedside is discussed.