Indocyanine green derived carbon dots with significantly enhanced properties for efficient photothermal therapy
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Abstract:
A simple yet effective strategy to enhance the thermal stability, anti-photobleaching and photothermal efficiency of indocyanine green via carbonization has been developed, which is likely to have broad applications in other systems.Keywords:
Indocyanine Green
Photobleaching
Thermal Stability
Photobleaching
Thionine
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近年来随着光动力疗法基础研究的不断深入，光敏剂光漂白及其机制研究日渐成为PDT研究的热点问题。本实验利用化学反应动力学原理对量子点CdSe在胎牛血清(FBS)和HL60细胞悬液的复杂溶液体系中的光漂白速率进行理论推导，得出其光漂白在单一溶液里符合一级动力学过程，在复杂溶液中满足二级反应动力学过程的结果。并通过测定量子点CdSe的紫外可见吸收光谱，利用比尔–朗伯吸收定律得到量子点CdSe的光漂白曲线和光漂白速率，通过拟合比较得出光漂白反应动力学规律，对实验结果进行了理论验证。 With the development of the basic research of photodynamic therapy (PDT), photosensitizer photobleaching has become a highly focused area of research within PDT in recent years. In this paper, the photobleaching mechanism of quantum dots in the FBS solution and HL60 cell solutions with oxygen substrate were investigated by the method of theoretical derivation. The results demonstrated that the photobleaching in the single solution was corresponded with the first order kinetics while the photobleaching in the complex solution was corresponded with the second order kinetics. The curve and rate of CdSe photobleaching were obtained by determining the vis absorption spectrum of the CdSe and using of the Beer. Additionally, the photobleaching properties of quantum dot (CdSe) whose theoretical derivation can be confirmed by our experiment were gained.
Photobleaching
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Background: In recent years, 5‐aminolaevulinic acid (ALA) has become an increasingly popular photosensitizing drug for use in both photodynamic therapy (PDT) and photodetection (PD) of cancers. ALA metabolizes within tissue to form the photosensitizer protoporphyrin IX (PpIX). Like most photosensitizers, PpIX is fluorescent, and this fluorescence progressively decreases during PDT. This phenomenon is referred to as photobleaching. Aim: Our aim in carrying out this experiment was twofold: firstly, to compare the relative capacity of red and blue light to cause photobleaching; and secondly, to compare the capacity of a fixed light dose to cause photobleaching, when delivered at different intensities. Method: In this paper, we describe the implementation of a compact fluorescence spectrometer in monitoring the photobleaching of ALA‐induced PpIX in vivo on the skin of healthy volunteers. Results: We have been able to show that blue light causes more rapid photobleaching than red light, and that under illumination with red or blue light, delivery of a fixed light dose at a lower intensity results in more photobleaching. Conclusion: Comparison of the photobleaching rates suggests that a blue light intensity of 5 mW/cm 2 gives the same rate of photobleaching as the typical red light PDT intensity of 100 mW/cm 2 . Further investigation of the correlation between PpIX photobleaching and PDT effect would be beneficial in interpreting the clinical significance of our findings.
Photobleaching
Protoporphyrin IX
Light intensity
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A novel photobleaching model was proposed, in which a D-P photobleaching mechanism was developed. By combining with the conventional D-D and D-O photobleaching mechanisms, the dependence of photobleaching rate on the excitation power is well illustrated. The validity of this model was demonstrated with GFP photobleaching experiments in cases of one-photon excitation (1PE) and two-photon excitation (2PE) respectively. Previously inexplicable experimental results published in literature were also illustrated with this new model.
Photobleaching
Two-photon excitation microscopy
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Photobleaching
Degradation
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With the development of the basic research of photodynamic therapy (PDT), photosensitizer photobleaching has become a highly focused area of research within PDT in recent years. In this paper, the photobleaching mechanism of quantum dots in the FBS solution and HL60 cell solutions with oxygen substrate were investigated by the method of theoretical derivation. The results demonstrated that the photobleaching in the single solution was corresponded with the first order kinetics while the photobleaching in the complex solution was corresponded with the second order kinetics. The curve and rate of CdSe photobleaching were obtained by determining the vis absorption spectrum of the CdSe and using of the Beer. Additionally, the photobleaching properties of quantum dot (CdSe) whose theoretical derivation can be confirmed by our experiment were gained.
Photobleaching
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1. The validity of a two-compartment pharmacokinetic model for the estimation of the hepatic extraction ratio of Indocyanine Green was tested in six patients with cirrhosis of the liver. 2. No agreement was found between the value of the hepatic extraction ratio measured directly and that calculated using the two-compartment model. 3. To investigate the reasons for the failure of the model, an extended sampling period was used to define the time course of Indocyanine Green in plasma in six healthy subjects and in six patients with cirrhosis of the liver after a bolus injection of the dye. 4. Indocyanine Green was measurable in the plasma for up to 10 h after injection in healthy subjects, and up to 48 h after injection in the patients. The plasma elimination curve in both groups was best described by a triexponential function. 5. The clearance of Indocyanine Green calculated using data collected in the first 20 min after injection overestimated that calculated using data collected for as long as Indocyanine Green was measurable in the plasma. In the patients with cirrhosis the mean overestimate was 87%. 6. Thus, a two-compartment pharmacokinetic model was inappropriate for the description of the disposition of Indocyanine Green and estimates of the hepatic extraction ratio obtained using this model in patients with cirrhosis were inaccurate.
Indocyanine Green
Bolus (digestion)
Liver function
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• To evaluate hepatic function, the kinetics of indocyanine green clearance were studied in seven injured patients with hepatic venous catheters. Indocyanine green clearance after a bolus injection of 20 mg was relatively monoexponential on the first day after injury. Following this, a second slower compartment of indocyanine green clearance was uniformly evident, becoming most prominent around the fourth day after injury. Indocyanine green clearance again became more uniform as recovery continued. Fractional indocyanine green extraction ten minutes after injection decreased from 0.9 on the first day after injury to 0.2 three days later, and then returned to 0.7 on the seventh day after injury. These decreases in indocyanine green clearance preceded an increase in total serum bilirubin concentration to a mean value of 1.9 mg/dL. Indocyanine green clearance was thus found to be an early and sensitive indicator of impaired hepatic function. (Arch Surg1984;119:264-268)
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Bolus (digestion)
Clearance
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Fluorescence correlation spectroscopy (FCS) can be used to investigate the photobleaching properties of fluorophores in solution. The advantage with this method is that in addition to the photobleaching rate the formation and decay rates of the triplet state can be measured. In this way, it is possible to calculate the photodestruction quantum yield and relate the photostability of a fluorescent compound in a certain environment to the photodynamical behaviour of the singlet-triplet transitions. This is likely to contribute to a better understanding of the mechanisms of photobleaching given the central importance of dye triplet states in photobleaching processes. The approach was applied to the measurement and characterization of the photobleaching of Rh6G in aqueous solution and FITC in 1 mM sodium carbonate buffer (pH 9). The photobleaching yields measured are discussed in view of the simultaneous triplet properties at different excitation intensities, oxygen concentrations as well as in the presence or absence of quencher molecules. This study suggests that FCS is likely to provide a valuable tool for the elucidation of the mechanisms of photobleaching, which are far from understood in all their details.
Photobleaching
Fluorescence Correlation Spectroscopy
Quantum yield
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Pyrylium salts were found to be attractive candidates for applications based on two-photon absorption effect. Especially, they have been used for three-dimensional data storage through photobleaching process. In the present work the photobleaching, under two-photon excitation, is investigated for a representative pyrylium salt hosted in a polymethylmethacrylate film. The photobleaching dependence on time, power and wavelength irradiation as well as on the film concentration is presented. Our results reveal the existence of two photobleaching mechanisms and indicate the presence of high-order interactions in these processes.
Photobleaching
Two-photon excitation microscopy
Excitation wavelength
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