Experimental study on photodynamic diagnosis of cancer mediated by chemiluminescence probe

Luminescence of Cypridina Luciferin in the Presence of Human Plasma Alpha 1-Acid Glycoprotein

The enzyme Cypridina luciferase (CLase) enables Cypridina luciferin to emit light efficiently through an oxidation reaction. The catalytic mechanism on the substrate of CLase has been studied, but the details remain to be clarified. Here, we examined the luminescence of Cypridina luciferin in the presence of several proteins with drug-binding ability. Luminescence measurements showed that the mixture of human plasma alpha 1-acid glycoprotein (hAGP) and Cypridina luciferin produced light. The total value of the luminescence intensity over 60 s was over 12.6-fold higher than those in the presence of ovalbumin, human serum albumin, or bovine serum albumin. In the presence of heat-treated hAGP, the luminescence intensity of Cypridina luciferin was lower than in the presence of intact hAGP. Chlorpromazine, which binds to hAGP, showed an inhibitory effect on the luminescence of Cypridina luciferin, both in the presence of hAGP and a recombinant CLase. Furthermore, BlastP analysis showed that hAGP had partial amino acid sequence similarity to known CLases in the region including amino acid residues involved in the drug-binding ability of hAGP. These findings indicate enzymological similarity between hAGP and CLase and provide insights into both the enzymological understanding of CLase and development of a luminescence detection method for hAGP.

Ultrasound-Enhanced Chemiluminescence for Bioimaging

Tissue imaging has emerged as an important aspect of theragnosis. It is essential not only to evaluate the degree of the disease and thus provide appropriate treatments, but also to monitor the delivery of administered drugs and the subsequent recovery of target tissues. Several techniques including magnetic resonance imaging (MRI), computational tomography (CT), acoustic tomography (AT), biofluorescence (BF) and chemiluminescence (CL), have been developed to reconstruct three-dimensional images of tissues. While imaging has been achieved with adequate spatial resolution for shallow depths, challenges still remain for imaging deep tissues. Energy loss is usually observed when using a magnetic field or traditional ultrasound (US), which leads to a need for more powerful energy input. This may subsequently result in tissue damage. CT requires exposure to radiation and a high dose of contrast agent to be administered for imaging. The BF technique, meanwhile, is affected by strong scattering of light and autofluorescence of tissues. The CL is a more selective and sensitive method as stable luminophores are produced from physiochemical reactions, e.g. with reactive oxygen species. Development of near infrared-emitting luminophores also bring potential for application of CL in deep tissues and whole animal studies. However, traditional CL imaging requires an enhancer to increase the intensity of low-level light emissions, while reducing the scattering of emitted light through turbid tissue environment. There has been interest in the use of focused ultrasound (FUS), which can allow acoustic waves to propagate within tissues and modulate chemiluminescence signals. While light scattering is decreased, the spatial resolution is increased with the assistance of US. In this review, chemiluminescence detection in deep tissues with assistance of FUS will be highlighted to discuss its potential in deep tissue imaging.

Real-Time Monitoring of Singlet Oxygen and Oxygen Partial Pressure During the Deep Photodynamic Therapy In Vitro

Photodynamic therapy (PDT) is an effective noninvasive method for the tumor treatment. The major challenge in current PDT research is how to quantitatively evaluate therapy effects. To our best knowledge, this is the first time to combine multi-parameter detection methods in PDT. More specifically, we have developed a set of system, including the high-sensitivity measurement of singlet oxygen, oxygen partial pressure and fluorescence image. In this paper, the detection ability of the system was validated by the different concentrations of carbon quantum dots. Moreover, the correlation between singlet oxygen and oxygen partial pressure with laser irradiation was observed. Then, the system could detect the signal up to 0.5 cm tissue depth with 660 nm irradiation and 1 cm tissue depth with 980 nm irradiation by using up-conversion nanoparticles during PDT in vitro. Furthermore, we obtained the relationship among concentration of singlet oxygen, oxygen partial pressure and tumor cell viability under certain conditions. The results indicate that the multi-parameter detection system is a promising asset to evaluate the deep tumor therapy during PDT. Moreover, the system might be potentially used for the further study in biology and molecular imaging.

Limits of application of initiated chemiluminescence in monitoring of oncological process of mucous membrane of mouth and larynx

Investigation into the limits of application of chemiluminescence (CL) methods in oncology still attracts the attention of researchers. In the present work we analyze the screening and monitoring of oncological processes (OP) in the mucous membrane of the mouth and larynx by initiated CL (ICL). Chemiluminescence has already been used by stomatologists to define the start of OP, but methods that reflect the metabolic changes in organism under cancer diagnostics still have not found their place. This work presents results of ICL on blood serum (BS) of patients with oncological diseases at different stages of medical treatment compared with those of healthy people. We found an essential metabolic difference only in types of OP that are characterized by two maxima on chemiluminograms. These OP represent only 12.81% of groups of patients with oncological diseases. The possibility to apply ICL methods to monitor operation quality and control medical treatment at different stages when the two ICL maxima are present is established. At present, the chemiluminograms with the two maxima are mostly informative, but this does not exclude the quantitative analysis of other ICL kinetic methods and is encouraging for their investigation. Any OP introduces changes in organism function and these should be reflected in the ICL. Copyright © 2016 John Wiley & Sons, Ltd.

Sonodynamic and sonocatalytic damage of BSA molecules by Cresol Red, Cresol Red-DA and Cresol Red-DA-Fe under ultrasonic irradiation

The interaction of Cresol Red derivatives (Cresol Red (o-Cresolsulfonphthalein), Cresol Red-DA (3,3'-Bis [N,N-di (carboxymethyl) aminomethyl]-o-cresolsulfonphthalein) and Cresol Red-DA-Fe(III) (3,3'-Bis [N,N-di (carboxymethyl) aminomethyl]-o-cresolsulfonphthalein-Ferrous(III)) with bovine serum albumin (BSA) were studied by the combination of ultraviolet spectroscopy, circular dichroism (CD) spectroscopy, fluorescence spectroscopy and synchronous fluorescence spectroscopy. On that basis, the sonodynamic and sonocatalytic damages of Cresol Red derivatives to BSA under ultrasonic irradiation were also investigated by means of corresponding spectrum technology. Meanwhile, some influenced factors such as ultrasonic irradiation time, Cresol Red derivatives concentration and ionic strength on the damage degree of BSA molecules were also reviewed. In addition, the binding site and damage site of BSA molecules were estimated by synchronous fluorescence spectra. Finally, the results of oxidation-extraction photometry (OEP) using several reactive oxygen species (ROS) scavengers indicated that the damage of BSA molecules is mainly due to the generation of ROS. Perhaps, this paper may offer some important subjects for broadening the application of Cresol Red derivatives in sonodynamic therapy (SDT) and sonocatalytic therapy (SCT) technologies for tumor treatment.

Pyropheophorbide A and c(RGDyK) comodified chitosan-wrapped upconversion nanoparticle for targeted near-infrared photodynamic therapy

Near-infrared (NIR)-to-visible upconversion nanoparticle (UCNP) has shown promising prospects in photodynamic therapy (PDT) as a drug carrier or energy donor. In this work, a photosensitizer pyropheophorbide a (Ppa) and RGD peptide c(RGDyK) comodified chitosan-wrapped NaYF(4):Yb/Er upconversion nanoparticle UCNP-Ppa-RGD was developed for targeted near-infrared photodynamic therapy. The properties of UCNP-Ppa-RGD, such as morphology, stability, optical spectroscopy and singlet oxygen generation efficiency, were investigated. The results show that covalently linked pyropheophorbide a molecule not only is stable but also retains its spectroscopic and functional properties. In vitro studies confirm a stronger targeting specificity of UCNP-Ppa-RGD to integrin α(v)β(3)-positive U87-MG cells compared with that in the corresponding negative group. The photosensitizer-attached nanostructure exhibited low dark toxicity and high phototoxicity against cancer cells upon 980 nm laser irradiation at an appropriate dosage. These results represent the first demonstration of a highly stable and efficient photosensitizer modified upconversion nanostructure for targeted near-infrared photodynamic therapy of cancer cells. The novel UCNP-Ppa-RGD nanoparticle may provide a powerful alternative for near-infrared photodynamic therapy with an improved tumor targeting specificity.

Monitoring singlet oxygen in situ with delayed chemiluminescence to deduce the effect of photodynamic therapy

Singlet oxygen ((1)O(2)) is an important factor mediating cell killing in photodynamic therapy (PDT). We previously reported that chemiluminescence (CL) can be used to detect (1)O(2) production in PDT and linked the signal to the PDT-induced cytotoxicity in vitro. We develop a new CL detection apparatus to achieve in vivo measurements. The system utilizes a time-delayed CL signal to overcome the interference from scattered excitation light, thus greatly improving the accuracy of the detection. The system is tested on healthy skin of BALB/ca mouse for its feasibility and reliability. The CL measurement is made during a synchronized gating period of the irradiation light. After each PDT treatment and in situ CL measurement, the skin response is scored over a period of 2 weeks. A remarkable relationship is observed between the score and the CL, regardless of the PDT treatment protocol. Although there are many issues yet to be addressed, our results clearly demonstrate the feasibility of CL measurement during PDT and its potential for in vivo PDT dosimetry. This requires further investigations.

Phototoxicity and fluorotoxicity combine to alter the behavior of neutrophils in fluorescence microscopy based flow adhesion assays

The use of fluorescent probes that allow visualization of leukocyte-endothelial cell (EC) interactions has greatly informed our understanding of leukocyte recruitment. However, effects of these agents on the biological functions of leukocytes are poorly described, leading to concerns about the interpretation of such data. Here we used two flow-based neutrophil adhesion assays to compare the effects of phase contrast illumination (PCI) with high intensity illumination (HII) used for fluorescent microscopy, in the presence or absence of five commonly used fluorochromes. Isolated neutrophils were either (1) perfused across P-selectin to establish a population of rolling cells, which were subsequently activated with fMLP; or (2) perfused across EC activated with TNF-alpha. In the absence of fluorescent dyes, HII did not affect levels of leukocyte adhesion; however, subsequent neutrophil behavior was dramatically altered when compared with cells under PCI, for example, dramatically reducing their migration velocities. In the presence of fluorescent dyes, the effects of HII were exacerbated, although the precise nature of the biological effects of these probes was agent specific. Thus, for the first time, our experiments describe the effects of fluorescent microscopy on the separate stages of the neutrophil recruitment process and reveal a previously unsuspected effect of HII on neutrophil migration.

A new chemiluminescence probe for singlet oxygen based on tetrathiafulvalene-anthracene dyad capable of performing detection in water/alcohol solution

A new tetrathiafulvalene-anthracene dyad 1 with two "tetraethylene glycol" units was synthesized and characterized. Strong chemiluminescence was observed upon reaction of dyad 1 with singlet oxygen (1O2), and this reaction shows fairly good selectivity toward 1O2 over other reactive oxygen species. Due to the introduction of two hydrophilic "tetraethylene glycol" units, the detection of 1O2 with dyad 1 can be performed in alcohol/water solution, which is relatively a mild medium when compared with water/tetrahydrofuran solution required by other tetrathiafulvalene-anthracene dyads. Dyad 1 may have a wider use for detection of 1O2 in biological systems.

Feasibility of using fluoresceinyl Cypridina luciferin analog in a novel chemiluminescence method for real-time photodynamic therapy dosimetry

Singlet oxygen ((1)O(2)) is the most important cytotoxic agent in photodynamic therapy (PDT). The feasibility of using a chemiluminescence (CL) probe, 3,7-dihydro-6-[4-(2-(N'-(5-fluoresceinyl)thioureido)ethoxy)phenyl]-2-methylimidazo{1,2-a}pyrazin-3-one sodium salt (fluoresceinyl Cypridina luciferin analog, FCLA), to monitor (1)O(2) production during PDT is evaluated in vitro. Lymphoma cells were treated with various protocols of PDT. The results show that the FCLA-CL production during PDT is linearly related to the corresponding cytotoxicity, regardless of the treatment protocol. With minimum cytotoxicity and interference to the PDT treatment outcome, the FCLA-CL system is an effective means to quantify PDT (1)O(2) production and may provide an alternative real-time dosimeter.

Determination of H2O2-dependent generation of singlet oxygen from human saliva with a novel chemiluminescence probe

Singlet oxygen (1O2) has been shown to play an important role in salivary defense system, but its generation process and level from human saliva remain uncertain due to the lack of a reliable detection method. We have previously reported 4,4'(5')-bis[2-(9-anthryloxy)ethylthio]tetrathiafulvalene (BAET) as a novel chemiluminescence probe for 1O2. In this work, the probe is successfully used to characterize H2O2-dependent generation of 1O2 from saliva in real time. However, the yield of 1O2 is found to be very low, for example, being about 0.13 nmol from 200 microL saliva in the presence of 1 mM of hydrogen peroxide over a 5-s reaction period. The result is also compared with that obtained with another 1O2 probe 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (CLA), demonstrating that, besides 1O2, the other reactive oxygen species such as hydroxyl radical may also be involved in the reaction of saliva with H2O2. Furthermore, the present study shows that the selectivity of BAET for 1O2 is much higher than that of CLA and thus BAET is highly suited for the detection of 1O2 in the presence of other reactive oxygen species in biological systems.

Enhancement of Fluoresceinyl Cypridina Luciferin Analog Chemiluminescence by Human Serum Albumin for Singlet Oxygen Detection

Fluoresceinyl cypridina luciferin analog (FCLA) is a chemiluminescence (CL) probe for detecting reactive oxygen species (ROS). Its efficiency for detecting singlet oxygen (1O2) can be significantly enhanced in the presence of human serum albumin (HSA). This phenomenon may apply to important applications for both research and clinical testing, because of the broad presence of HSA in the human system. In the current study the mechanism of the FCLA-HSA CL system is studied by means of direct CL measurement and spectroscopy techniques. Our results show that FCLA can combine with HSA via a single binding site to form a complex. The CL efficiency of the system is largely governed by an intersystem energy transfer between the two components upon interaction with 1O2. The CL production reaches maximum in a synergetic manner when equal amounts of FCLA and HSA are present simultaneously, but production is less at other ratios. The results also show that the combination of FCLA with HSA does not significantly alter the ROS selectivity of FCLA. In conclusion, our study shows that FCLA and HSA can combine and form a complex with higher CL efficiency. This provides us a new approach in designing CL techniques for studying ROS.

Cyclodextrin-bound 6-(4-methoxyphenyl)imidazo[1,2-alpha+/-]pyrazin-3(7H)-ones with fluorescein as green chemiluminescent probes for superoxide anions

In providing chemiluminescent probes that have high chemiluminescence intensity and high specificity to superoxide anions, novel chemiluminescent probes involving cyclodextrins covalently bound to 6-(4-methoxyphenyl)imidazo[1,2-alpha]pyrazin-3(7H)-one with fluorescein were synthesized and characterized. Using the hypoxanthine-xanthine oxidase system for the generation of the superoxide anions, these novel chemiluminescent probes showed higher superoxide-induced chemiluminescence intensity than that of 6-[4-[2-[N(')-(5-fluoresceinyl)thioureido]-ethoxy]phenyl]-2-methylimidazo[1,2-alpha]pyrazin-3(7H)-one (FCLA). When tested at a probe concentration of 1.0 microM, compound 6, in which 6-(4-methoxyphenyl)imidazo[1,2-alpha]pyrazin-3(7H)-one and fluorescein are covalently attached on the secondary and primary hydroxyl faces of gamma-cyclodextrin, respectively, showed green luminescence intensity that was 26 times that of FCLA, which was also the highest luminescence intensity in this present study. At probe concentrations of less than 1.0 microM, the ratio of the superoxide-dependent chemiluminescence intensity to the background chemiluminescence intensity for compound 6 was higher than that of FCLA. This high superoxide-induced chemiluminescence intensity and superoxide specificity in low probe concentrations indicates that 6 can be more effective than FCLA toward the measurement of superoxide anions.

Improvement of low-level light imaging performance using optical clearing method

Low-level light-emitting imaging technique often detects the light emerged at the tissue surface that is generated internally from a specific target. However, in most cases, the high scattering nature of biological tissue limits the sensitivity and spatial resolution of this imaging modality. In this paper, we report that a significant improvement of chemiluminescence (CL) imaging performance in terms of both sensitivity and spatial resolution can be achieved by use of the topical application of glycerol solution onto tissue sample, i.e. optical clearing approach. Monte Carlo (MC) simulation of internally-launched point source shows that the decrease of scattering coefficient of turbid medium, which can be achieved by optical tissue clearing approach, causes stronger peak intensity with a narrower full-width at half-maximum (FWHM). The improvement becomes more significant with the source depth increasing from 1 to 5 mm. The experimental results shows that tissue clearing with 50% glycerol solution could largely improve the brightness and the spatial resolution of CL imaging when the target is covered by biological tissue with a thickness of either 1 or 3mm. This method could have potential applications for the in vivo low-level light imaging techniques.

Detection of reactive oxygen species in the skin of live mice and rats exposed to UVA light: a research review on chemiluminescence and trials for UVA protection

The harmful effects of ultraviolet (UV) exposure on the skin are associated with the generation of reactive oxygen species (ROS) such as superoxide anion radical ( O(2)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radical ( OH), and singlet oxygen ((1)O(2)) as well as with lipid peroxides and their radicals (LOOH and LOO ). To give direct proof that such ROS are generated in UV-exposed skin, we proposed the in vivo detection and imaging method in which both a sensitive and specific chemiluminescence (CL) probe, such as CLA, and an ultralow-light imaging apparatus with a CCD camera were used. With this method we found that O(2)(-) is formed intrinsically and that (1)O(2) and O(2)(-) are generated in the UVA-exposed skin of mice. In addition, we indicated that antioxidative ability against ROS in the skin of hairless rats decreased as age increased. Using these findings, we demonstrated the protective abilities of sodium ascorbate, caffeic acid, essential aroma oils, and zinc(ii) ion and its complexes, which we administered to mice both topically and orally. We present a review for the current state of our research proposing the sensitive CL method as a useful in vivo tool in photobiological research for the detection of oxidative stress as well as for the evaluation of antioxidative agents to the skin.

Reestimation of Cypridina luciferin analogs (MCLA) as a chemiluminescence probe to detect active oxygen species--cautionary note for use of MCLA

Cypridina luciferin analogs have been widely used as a specific chemiluminescence probe for the detection of superoxide anion (O2-) and singlet oxygen (1O2). However, light emission during the reaction of Cypridina luciferin analogs and other active oxygen species (AOS) has not been reported in detail. Therefore, we re-evaluated 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazine-3-one (MCLA), one of the Cypridina luciferin analogs, as a chemiluminescence probe to detect various AOS. MCLA-dependent chemiluminescence was observed when MCLA was incubated with the following systems; 1) hypoxanthine plus xanthine oxidase (O2-), 2) thermolysis of endoperoxide (1O2), 3) hydrogen peroxide plus ferrous ion (hydroxyl radical), 4) ferrous ion, 5) thermolysis of azo compound (alkyl peroxyl radical) and 6) hydrogen peroxide. Superoxide dismutase inhibited MCLA-dependent chemiluminescence observed during ferrous ion-induced decomposition of hydrogen peroxide. Alkyl peroxyl radical reacted with MCLA, but light was not emitted when the concentration of MCLA was high. These results suggest that radicals, except O2-, appeared not to be direct inducers of MCLA-dependent light emission. In summary, MCLA-dependent chemiluminescence was induced by various AOS in addition to O2- and 1O2, but active species must be O2- and 1O2 in many cases. These points should be appreciated when Cypridina luciferin analogs, such as MCLA, are used for the detection of AOS.