In vivo monitoring of singlet oxygen using delayed chemiluminescence during photodynamic therapy

Investigate the Possibility of Using Phosphorescence in Clinical Oncology as an Early Prognostic Test in Detecting Brain Carcinogenesis

Phosphorescence is considered one of the non-invasive glioblastoma testing methods based on studying molecular energy and the metabolism of L-tryptophan (Trp) through KP, which provides essential information on regulating immunity and neuronal function. This study aimed to conduct a feasibility study using phosphorescence in clinical oncology as an early prognostic test in detecting Glioblastoma. This study was conducted on 1039 patients who were operated on with follow-up between January 1, 2014, and December 1, 2022, and retrospectively evaluated in participating institutions in Ukraine (the Department of Oncology, Radiation Therapy, Oncosurgery, and Palliative Care at the Kharkiv National Medical University). Method of protein phosphorescence detection included two steps. During the first step, of luminol-dependent phosphorescence intensity in serum was carried out after its activation by the light source, according to the spectrofluorimeter method, as follows. At a temperature of 30 °C, serum drops were dried for 20 min to form a solid film. After that, we put the quartz plate with dried serum in a phosphoroscope of luminescent complex and measured the intensity. With the help of Max-Flux Diffraction Optic Parallel Beam Graded Multilayer Monochromator (Rigaku Americas Corporation) following spectral lines as 297, 313, 334, 365, 404, and 434 nm were distinguished and absorbed by serum film in the form of light quantum. The monochromator exit split width was 0.5 mm. Considering the limitations of each of the non-invasive tools currently available, phosphorescence-based diagnostic methods are ideally integrated into the NIGT platform: a non-invasive approach for visualizing a tumor and its main tumor characteristics in the spatial and temporal order. Because trp is present in virtually every cell in the body, these fluorescent and phosphorescent fingerprints can be used to detect cancer in many different organs. Using phosphorescence, it is possible to create predictive models for GBM in both primary and secondary diagnostics. This will assist clinicians in selecting the appropriate treatment option, monitoring treatment, and adapting to the era of patient-centered precision medicine.

Method for monitoring singlet oxygen quantum yield in real time by time resolved spectroscopy measurement

The singlet oxygen quantum yield (Φ_Δ) was monitored in real time through time resolved spectroscopy measurement, using gadolinium labeled hematoporphyrin monomethyl ether (Gd-HMME) as photosensitizer. According to the kinetics equations of singlet oxygen generation and reaction, Φ_Δ was related to phosphorescence lifetime (τ_p). Through measuring τ_p of Gd-HMME in different oxygen conditions, the radiation transition property of first exited triplet state (T₁) was monitored; combined with the triplet state quantum yield (Φ_T) determined by linear fitting the Φ_Δ, which was measured in different oxygen content using a relative measurement, Φ_Δ can be determined in real time. The identification of anoxia during the treatment of photodynamic therapy (PDT) by this method is also presented.

Carbon dot-assisted luminescence of singlet oxygen: the generation dynamics but not the cumulative amount of singlet oxygen is responsible for the photodynamic therapy efficacy

A novel carbon dot-based luminescence probe for singlet oxygen (¹O₂) with a conventional optical detector has been implemented through the specific formation of electronically excited carbonyls from the breakdown of unstable endoperoxide intermediates, and its application in the real-time in vivo monitoring of ¹O₂ in photodynamic therapy (PDT) is achieved. More attractively, the relationship between the dynamics details of photosensitizer-generated ¹O₂ and the PDT efficacy has been established through a modified multiple-target survival model, enabling a direct and easy estimate of the surviving fraction of tumor cells from the generation dynamics of ¹O₂. Both in vitro and in vivo therapy results revealed that the rapid generation dynamics of ¹O₂ rather than its cumulative amount is responsible for better treatment efficacy in PDT. Overall, the deeper insight into the important roles of the generation dynamics of ¹O₂ in the PDT efficacy is irreplaceably advantageous in substantially reduced risks from deleterious treatment-related side effects by screening advanced photosensitizers and determining the light exposure end point.

Reactive Oxygen Species Explicit Dosimetry for Photofrin-mediated Pleural Photodynamic Therapy

Explicit dosimetry of treatment light fluence and implicit dosimetry of photosensitizer photobleaching are commonly used methods to guide dose delivery during clinical PDT. Tissue oxygen, however, is not routinely monitored intraoperatively even though it is one of the three major components of treatment. Quantitative information about in vivo tissue oxygenation during PDT is desirable, because it enables reactive oxygen species explicit dosimetry (ROSED) for prediction of treatment outcome based on PDT-induced changes in tumor oxygen level. Here, we demonstrate ROSED in a clinical setting, Photofrin-mediated pleural photodynamic therapy, by utilizing tumor blood flow information measured by diffuse correlation spectroscopy (DCS). A DCS contact probe was sutured to the pleural cavity wall after surgical resection of pleural mesothelioma tumor to monitor tissue blood flow (blood flow index) during intraoperative PDT treatment. Isotropic detectors were used to measure treatment light fluence and photosensitizer concentration. Blood-flow-derived tumor oxygen concentration, estimated by applying a preclinically determined conversion factor of 1.5 × 10⁹ μMs cm^-2 to the blood flow index, was used in the ROSED model to calculate the total reacted reactive oxygen species [ROS]rx. Seven patients and 12 different pleural sites were assessed and large inter- and intrapatient heterogeneities in [ROS]rx were observed although an identical light dose of 60 J cm^-2 was prescribed to all patients.

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.

Dual-channel imaging system for singlet oxygen and photosensitizer for PDT

A two-channel optical system has been developed to provide spatially resolved simultaneous imaging of singlet molecular oxygen ((1)O(2)) phosphorescence and photosensitizer (PS) fluorescence produced by the photodynamic process. The current imaging system uses a spectral discrimination method to differentiate the weak (1)O(2) phosphorescence that peaks near 1.27 μm from PS fluorescence that also occurs in this spectral region. The detection limit of (1)O(2) emission was determined at a concentration of 500 nM benzoporphyrin derivative monoacid (BPD) in tissue-like phantoms, and these signals observed were proportional to the PS fluorescence. Preliminary in vivo images with tumor laden mice indicate that it is possible to obtain simultaneous images of (1)O(2) and PS tissue distribution.

Increasing the efficiency of photodynamic therapy by improved light delivery and oxygen supply using an anticoagulant in a solid tumor model

BACKGROUND AND OBJECTIVE

The main factors in photodynamic therapy (PDT) are: photosensitizer retention, photon absorption, and oxygen supply. Each factor has its unique set of problems that poses limitation to the treatment. Both light delivery and oxygen supply are significant bottlenecks in PDT. Vascular closure during PDT reduces oxygen supply to the targeted tissue. On the other hand, with the changes in blood perfusion, the tissue optical properties change, and result in variation in irradiation light transmission. For these reasons, it becomes very important to avoid blood coagulation and vascular closure during PDT.

STUDY DESIGN/MATERIALS AND METHODS

The efficiency of PDT combined with the anticoagulant heparin was studied in a BALB/c mouse model with subcutaneous EMT6 mammary carcinomas. Mice were randomized into three groups: control, PDT-only, and PDT with heparin. The photosensitizer Photofrin was used in our experiments. Light transmission, blood perfusion, and local production of reactive oxygen species (ROS) were monitored during the treatment. The corresponding histological examinations were performed to determine the thrombosis immediately after irradiation and to evaluate tumor necrosis 48 hours after the treatment.

RESULTS

The results clearly demonstrated that PDT combined with pre-administered heparin can significantly reduce thrombosis during light irradiation. The blood perfusion, oxygen supply, and light delivery are all improved. Improved tumor responses in the combined therapy, as shown with the histological examination and tumor growth assay, are clearly demonstrated and related to an increased local ROS production.

CONCLUSION

Transitory anticoagulation treatment significantly enhances the antitumor effect of PDT. It is mainly due to the improvement of the light delivery and oxygen supply in tumor, and ultimately the amount of ROS produced during PDT.

Quantitative measurement of reactive oxygen species in vivo by utilizing a novel method: chemiluminescence with an internal fluorescence as reference

Reactive oxygen species (ROS) produced by photodynamic therapy (PDT) is recorded in vivo using a chemiluminescence (CL)-based gated optical system. A novel approach is developed to utilize the fluorescence (FL) of the CL probe as an internal fluorescence to calibrate the observed CL on pharmacokinetics of the probe in situ. The results show that during an in vivo PDT session, the intensity of CL decreases significantly and the decaying of CL is governed by fast and slow time components. By comparing the temporal profile of FL to that of the corresponding CL, it is found that the slow component is mainly attributed to the probe pharmacokinetics, whereas the fast component is likely due to rapid oxygen consumption as a result of PDT treatment. With carefully selected criteria, it is possible to minimize the effect of probe pharmacokinetics. This significantly improves the monitoring method for practical applications.

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.

Time dependence of singlet oxygen luminescence provides an indication of oxygen concentration during oxygen consumption

Singlet oxygen plays a major role in photodynamic inactivation of tumor cells or bacteria. Its efficacy depends critically on the oxygen concentration [O(2)], which can decrease in case oxygen is consumed caused by oxidative reactions. When detecting singlet oxygen directly by its luminescence at 1270 nm, the course of the luminescence signal is critically affected by [O(2)]. Thus, it should be feasible to monitor oxygen consumption during photo-oxidative processes. Singlet oxygen was generated by exciting a photosensitizer (TMPyP) in aqueous solution (H(2)O or D(2)O) of albumin. Chromatography shows that most of the TMPyP molecules are unbound, and therefore singlet oxygen molecules can diffuse in the solution. A sensor device for oxygen concentration revealed a rapid decrease of [O(2)] (oxygen depletion) in the solution during irradiation. The extent of oxygen depletion in aqueous albumin solution depends on the radiant exposure and the solvent. When detecting the luminescence signal of singlet oxygen, the shape of the luminescence signal significantly changed with irradiation time. Thus, local oxygen consumption could be monitored during photodynamic action by evaluating the course of singlet oxygen luminescence.