Pulsed diode laser-based monitor for singlet molecular oxygen

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.

Singlet Molecular Oxygen: from COIL Lasers to Photodynamic Cancer Therapy

Translation of experimental techniques from one scientific discipline to another is often difficult but rewarding. Knowledge gained from the new area can lead to long lasting and fruitful collaborations with concomitant development of new ideas and studies. In this Review Article, we describe how early work on the chemically pumped atomic iodine laser (COIL) led to the development of a key diagnostic for a promising cancer treatment known as photodynamic therapy (PDT). The highly metastable excited state of molecular oxygen, a1Δg, also known as singlet oxygen, is the link between these disparate fields. It powers the COIL laser and is the active species that kills cancer cells during PDT. We describe the fundamentals of both COIL and PDT and trace the development path of an ultrasensitive dosimeter for singlet oxygen. The path from COIL lasers to cancer research was relatively long and required medical and engineering expertise from numerous collaborations. As we show below, the knowledge gained in the COIL research, combined with these extensive collaborations, has resulted in our being able to show a strong correlation between cancer cell death and the singlet oxygen measured during PDT treatments of mice. This progress is a key step in the eventual development of a singlet oxygen dosimeter that could be used to guide PDT treatments and improve outcomes.

A biodegradable fluorescent nanohybrid for photo-driven tumor diagnosis and tumor growth inhibition

Specific targeting and phototriggered therapy in mouse model have recently emerged as the starting point of cancer theragnosis. Herein, we report a bioresponsive and degradable nanohybrid, a liposomal nanohybrid decorated with red emissive carbon dots, for localized tumor imaging and light-mediated tumor growth inhibition. Unsaturated carbon dots (C-dots) anchored to liposomes convert near-infrared (NIR) light into heat and also produce reactive oxygen species (ROS), demonstrating the capability of phototriggered cancer cell death and tumor regression. The photothermal and oxidative damage of breast tumor by the nonmetallic nanohybrid has also been demonstrated. Designed nanoparticles show excellent aqueous dispersibility, biocompatibility, light irradiated enhanced cellular uptake, release of reactive oxygen species, prolonged and specific tumor binding ability and good photothermal response (62 °C in 5 minutes). Safe and localized irradiation of 808 nm light demonstrates significant tumor growth inhibition and bioresponsive degradation of the fluorescent nanohybrid without affecting the surrounding healthy tissues.

Experimental Proof for the Role of Nonlinear Photoionization in Plasmonic Phototherapy

Targeting individual cells within a heterogeneous tissue is a key challenge in cancer therapy, encouraging new approaches for cancer treatment that complement the shortcomings of conventional therapies. The highly localized interactions triggered by focused laser beams promise great potential for targeting single cells or small cell clusters; however, most laser-tissue interactions often involve macroscopic processes that may harm healthy nearby tissue and reduce specificity. Specific targeting of living cells using femtosecond pulses and nanoparticles has been demonstrated promising for various potential therapeutic applications including drug delivery via optoporation, drug release, and selective cell death. Here, using an intense resonant femtosecond pulse and cell-specific gold nanorods, we show that at certain irradiation parameters cell death is triggered by nonlinear plasmonic photoionization and not by thermally driven processes. The experimental results are supported by a physical model for the pulse-particle-medium interactions. A good correlation is found between the calculated total number and energy of the generated free electrons and the observed cell death, suggesting that femtosecond photoionization plays the dominant role in cell death.

Spatiotemporally photoradiation-controlled intratumoral depot for combination of brachytherapy and photodynamic therapy for solid tumor

In an attempt to spatiotemporally control both tumor retention and the coverage of anticancer agents, we developed a photoradiation-controlled intratumoral depot (PRCITD) driven by convection enhanced delivery (CED). This intratumoral depot consists of recombinant elastin-like polypeptide (ELP) containing periodic cysteine residues and is conjugated with a photosensitizer, chlorin-e6 (Ce6) at the N-terminus of the ELP. We hypothesized that this cysteine-containing ELP (cELP) can be readily crosslinked through disulfide bonds upon exposure to oxidative agents, specifically the singlet oxygen produced during photodynamic stimulation. Upon intratumoral injection, CED drives the distribution of the soluble polypeptide freely throughout the tumor interstitium. Formation and retention of the depot was monitored using fluorescence molecular tomography imaging. When imaging shows that the polypeptide has distributed throughout the entire tumor, 660-nm light is applied externally at the tumor site. This photo-radiation wavelength excites Ce6 and generates reactive oxygen species (ROS) in the presence of oxygen. The ROS induce in situ disulfide crosslinking of the cysteine thiols, stabilizing the ELP biopolymer into a stable therapeutic depot. Our results demonstrate that this ELP design effectively forms a hydrogel both in vitro and in vivo. These depots exhibit high stability in subcutaneous tumor xenografts in nude mice and significantly improved intratumoral retention compared to controls without crosslinking, as seen by fluorescent imaging and iodine-125 radiotracer studies. The photodynamic therapy provided by the PRCITD was found to cause significant tumor inhibition in a Ce6 dose dependent manner. Additionally, the combination of PDT and intratumoral radionuclide therapy co-delivered by PRCITD provided a greater antitumor effect than either monotherapy alone. These results suggest that the PRCITD could provide a stable platform for delivering synergistic, anti-cancer drug depots.

Clinical use of photodynamic therapy in ocular tumors

Although the introduction of intravitreal anti-vascular endothelial growth factor drugs reduced the indications for photodynamic therapy in ophthalmology, it may still be used in various ocular tumors. Although many studies have shown that photodynamic therapy is effective in ocular tumors, the literature consists of case reports and series. In this review, we systematically performed a meta-analysis for the use of photodynamic therapy in circumscribed choroidal hemangioma, diffuse choroidal hemangioma, retinal capillary hemangioma, von Hippel-Lindau angiomatosis, choroidal melanoma, retinal astrocytoma, retinoblastoma, eyelid tumors, conjunctival tumors, and choroidal metastasis.

Temperature and oxygen-concentration dependence of singlet oxygen production by RuPhen as induced by quasi-continuous excitation

Assessment of partial pressure of oxygen (pO2) by luminescence lifetime measurements of ruthenium coordination complexes has been studied intensively during the last few decades. RuPhen (dichlorotris(1,10-phenanthroline) ruthenium(ii) hydrate) is a water soluble molecule that has been tested previously for in vivo pO2 detection. In this work we intended to shed light on the production of singlet oxygen by RuPhen. The quantum yield of singlet oxygen production by RuPhen dissolved in 0.9% aqueous NaCl solution (pH = 6) was measured at physiological temperatures (285-310 K) and various concentrations of molecular oxygen. In order to minimize the bleaching of RuPhen, the samples were excited with low power (<2 mW) laser pulses (20 μs long), created by pulsing a cw laser beam with an acousto-optical modulator. We show that, whereas the RuPhen phosphorescence lifetime decreases rapidly with an increase of temperature (keeping the oxygenation level constant), the quantum yield of singlet oxygen production by RuPhen is almost identical in the temperature range of 285-310 K. For air-saturated conditions at 310 K the measured quantum yield is about 0.25. The depopulation rate constants of the RuPhen (3)MLCT (metal-to-ligand charge-transfer) state are determined in the absence and in the presence of oxygen. We determined that the excitation energy for the RuPhen (3)MLCT→d-d transition is 49 kJ mol(-1) in the 0.9% NaCl solution (pH = 6).

Photosensitizer fluorescence and singlet oxygen luminescence as dosimetric predictors of topical 5-aminolevulinic acid photodynamic therapy induced clinical erythema

The need for patient-specific photodynamic therapy (PDT) in dermatologic and oncologic applications has triggered several studies that explore the utility of surrogate parameters as predictive reporters of treatment outcome. Although photosensitizer (PS) fluorescence, a widely used parameter, can be viewed as emission from several fluorescent states of the PS (e.g., minimally aggregated and monomeric), we suggest that singlet oxygen luminescence (SOL) indicates only the active PS component responsible for the PDT. Here, the ability of discrete PS fluorescence-based metrics (absolute and percent PS photobleaching and PS re-accumulation post-PDT) to predict the clinical phototoxic response (erythema) resulting from 5-aminolevulinic acid PDT was compared with discrete SOL (DSOL)-based metrics (DSOL counts pre-PDT and change in DSOL counts pre/post-PDT) in healthy human skin. Receiver operating characteristic curve (ROC) analyses demonstrated that absolute fluorescence photobleaching metric (AFPM) exhibited the highest area under the curve (AUC) of all tested parameters, including DSOL based metrics. The combination of dose-metrics did not yield better AUC than AFPM alone. Although sophisticated real-time SOL measurements may improve the clinical utility of SOL-based dosimetry, discrete PS fluorescence-based metrics are easy to implement, and our results suggest that AFPM may sufficiently predict the PDT outcomes and identify treatment nonresponders with high specificity in clinical contexts.

High levels of reactive oxygen species in gold nanoparticle-targeted cancer cells following femtosecond pulse irradiation

Cancer cells could be locally damaged using specifically targeted gold nanoparticles and laser pulse irradiation, while maintaining minimum damage to nearby, particle-free tissue. Here, we show that in addition to the immediate photothermal cell damage, high concentrations of reactive oxygen species (ROS) are formed within the irradiated cells. Burkitt lymphoma B cells and epithelial breast cancer cells were targeted by antibody-coated gold nanospheres and irradiated by a few resonant femtosecond pulses, resulting in significant elevation of intracellular ROS which was characterized and quantified using time-lapse microscopy of different fluorescent markers. The results suggest that techniques that involve targeting of various malignancies using gold nanoparticles and ultrashort pulses may be more effective and versatile than previously anticipated, allowing diverse, highly specific set of tools for local cancer therapy.

Porous silicon nanoparticle photosensitizers for singlet oxygen and their phototoxicity against cancer cells

Porous Si nanoparticles, prepared from electrochemically etched single crystal Si wafers, function as photosensitizers to generate (1)O(2) in ethanol and in aqueous media. The preparation conditions for the porous Si nanoparticles were optimized to maximize (1) the yield of material; (2) its quantum yield of (1)O(2) production; and (3) its in vitro degradation properties. The optimal formulation was determined to consist of nanoparticles 146 ± 7 nm in diameter, with nominal pore sizes of 12 ± 4 nm. The quantum yield for (1)O(2) production is 0.10 ± 0.02 in ethanol and 0.17 ± 0.01 in H(2)O. HeLa or NIH-3T3 cells treated with 100 μg/mL porous Si nanoparticles and exposed to 60 J/cm(2) white light (infrared filtered, 100 mW/cm(2) for 10 min) exhibit ∼45% cell death, while controls containing no nanoparticles show 10% or 25% cell death, respectively. The dark control experiment yields <10% cytotoxicity for either cell type.

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.

Pulsed diode laser-based singlet oxygen monitor for photodynamic therapy: in vivo studies of tumor-laden rats

Photodynamic therapy (PDT) is a promising cancer treatment that involves optical excitation of photosensitizers that promote oxygen molecules to the metastable O(2)(a(1)Delta) state (singlet oxygen). This species is believed to be responsible for the destruction of cancerous cells during PDT. We describe a fiber optic-coupled, pulsed diode laser-based diagnostic for singlet oxygen. We use both temporal and spectral filtering to enhance the detection of the weak O(2)(a-->X) emission near 1.27 microm. We present data that demonstrate real-time singlet oxygen production in tumor-laden rats with chlorin e6 and 5-aminolevulinic acid-induced protoporphyrin photosensitizers. We also observe a positive correlation between post-PDT treatment regression of the tumors and the relative amount of singlet oxygen measured. These results are promising for the development of the sensor as a real-time dosimeter for PDT.

In-vivo singlet oxygen dosimetry of clinical 5-aminolevulinic acid photodynamic therapy

Photodynamic therapy (PDT) is a viable treatment option for a wide range of applications, including oncology, dermatology, and ophthalmology. Singlet oxygen is believed to play a key role in the efficacy of PDT, and on-line monitoring of singlet oxygen during PDT could provide a methodology to establish and customize the treatment dose clinically. This work is the first report of monitoring singlet oxygen luminescence in vivo in human subjects during PDT, demonstrating the correlation of singlet oxygen levels during PDT with the post-PDT photobiological response.