Singlet Oxygen Delivery Through the Porous Cap of a Hollow-Core Fiber Optic Device

The development of the first photosensitizer/fiber optic device is reported. An oxygen-flowing, fiber-capped configuration is used for the application of heterogeneous, spatially confined singlet oxygen delivery in aqueous media. This is a unique device, unlike other heterogeneous photosensitizers, in which local concentrations of singlet oxygen can be delivered via introduction and withdrawal of the fiber tip

Singlet Oxygen Chemistry in Water. 2. Photoexcited Sensitizer Quenching by O2 at the Water−Porous Glass Interface

Insight into the O2 quenching mechanism of a photosensitizer (static or dynamic) would be useful for the design of heterogeneous systems to control the mode of generation of 1O2 in water. Here, we describe the use of a photosensitizer, meso-tetra(N-methyl-4-pyridyl)porphine (1), which was adsorbed onto porous Vycor glass (PVG). A maximum loading of 1.1 × 10−6 mol 1 per g PVG was achieved. Less than 1% of the PVG surface was covered with photosensitizer 1, and the penetration of 1 reaches a depth of 0.32 mm along all faces of the glass. Time-resolved measurements showed that the lifetime of triplet 1*-ads was 57 μs in water. Triplet O2 quenched the transient absorption of triplet 1*-ads; for samples containing 0.9 × 10−6−0.9 × 10−8 mol 1 adsorbed per g PVG, the Stern−Volmer constant, KD, ranged from 23 700 to 32 100 M−1. The adduct formation constant, KS, ranged from 1310 to 510 M−1. The amplitude of the absorption at 470 nm decreased slightly (by about 0.1) with increased O2 concentrations. Thus, the quenching behavior of triplet 1*-ads by O2 was proposed to be strongly dependent on dynamic quenching. Only ∼10% of the quenching was attributed to the static quenching mechanism. The quenching of triplet 1*-ads was similar to that observed for photosensitizers in homogeneous solution which are often quenched dynamically by O2

Assessment of spin-lattice T1 and spin-spin T2 relaxation time measurements in breast cell cultures at 1.5 Tesla as a potential diagnostic tool in vitro

Magnetic resonance imaging (MRI) is a critically important tool in current medicine. This dynamic diagnostic method allows for detailed and accurate imaging of the human body and diagnosis of metabolic changes by magnetic resonance spectroscopy (MRS) assays. Our work presented herein shows measurement of spin-lattice T1 and spin-spin T2 relaxation time as an indicator of changes in cellular morphology. MRI spin-lattice T1 and spin-spin T2 relaxation time measurements are innovative experiments that provide a detailed picture of the biological microenvironment within cell cultures. Here, we used two types of cell cultures: cancerous and healthy breast cells. By measuring spin-lattice T1 and spin-spin T2 relaxation time in cancerous and healthy cell cultures we can detect differences and morphological conditions of both cell lines. A number of observations indicate that MRI can detect differences between cancer and healthy cells. In order to obtain a high density of cells for our cellular MRI study, we grew the cells in 3D geometry. In this paper, we underline the potential of quantitative MRI in vitro for future cellular mapping of drug concentration and drug efficiency in cell culture. We have shown that MRI, which is used often for imaging of anatomy, is also a promising technology for specific morphological measurements of cells

Solid pseudopapillary neoplasm of the pancreas: a case report

This paper presents a case report of a solid pseudopapillary neoplasm (SPN) of the pancreas, a discussion on the clinical-pathological, histopathological, and immunohistochemical picture, and a review of the literature regarding the occurrence of this type of cancer. The case of a 61-year-old woman with the presence of a lithium-cystic lesion of the body and tail of the pancreas was initially assessed by MRI as a pathological mass with the presence of abscesses. Double biopsy under EUS control was non-diagnostic. The patient underwent surgery to remove the body and tail of the pancreas together with the tumour and spleen. Tumour size 15×10×8 cm lithium-cystic, grey-brown, with the presence of numerous calcifications and bone metaplasia, and stones in the pancreatic duct. In the histopathological picture, solid woven with the presence of pseudodimplants and pseudocystic areas with haemorrhages. Positive tests for NSE, vimentin, PR, CD56, and cyclin D1 were obtained in immunohistochemical (IHC) tests. The patient was discharged from the hospital in good general condition and is under gastroenterological control. SPN is a rare cancer with low malignancy. The tumour most often occurs in teenagers or young women. Initially, it runs without ailments, until it is large. Then there is pain, nausea, and fever. The histopathological and cytological picture is suggestive, but it should be supported by research. SPN should be differentiated with neuroendocrine tumours (NENs) and acinar cancer and pancreatoblasoma. SPN generally has a good prognosis. Local relapses and distant metastases are rare

Singlet Oxygen Chemistry in Water: A Porous Vycor GlassSupported Photosensitizer

Singlet molecular oxygen [1O2 (1Δg)] is generated cleanly in aqueous solution upon irradiation of a heterogeneous complex, meso-tetra(N-methyl-4-pyridyl)porphine (1) adsorbed onto porous Vycor glass (PVG). The cationic photosensitizer 1 tightly binds onto PVG and gives a stable material, which does not dissociate 1 into the surrounding aqueous phase. The production of 1O2 was measured by monitoring the time-resolved 1O2 (1Δg) phosphorescence at 1270 nm. Indirect analysis of 1O2 generation was also carried out with the photooxidation oftrans-2-methyl-2-pentenoate anion, which afforded the corresponding hydroperoxide. Sensitizer-1-impregnated PVG gives rise to a new singlet oxygen generator but more importantly provides a heterogeneous system for use in water

A Review of Sunlight Induced Cellular DNA Damage

We reviewed the literature on sunlight-induced DNA damage that leads to cancer in humans. Topics covered in this review are an introduction to sunlight radiation and examples of photo-induced DNA damage. The studies on sunlight radiation are covered in a brief discussion of ultraviolet (UV) and UV wavelengths such as UV-A, UV-B and UV-C that are known to induce cancer. The current literature covering a variety of cellular interactions with the UV component of sunlight from the point of view of photoactivated processes are discussed. We also discuss the chemical products of DNA sunlight induced damage. Based on the literature reviewed, a conclusion can be drawn that the UV component of sunlight is the most important epidemiological factor associated with an increased risk of human cancer. Sunlight-induced DNA damage also affects tissue homeostasis

Cellular Flow Cytometric Studies

This review focuses on flow cytometric studies at the single cell level. Currently, flow cytometry is used to analyze DNA content, cell cycle distribution, cellular viability, apoptosis, calcium flux, intracellular pH and expression of cell surface compounds in targeted cell populations. Our criteria for the selection of research papers for this review were focused on those that show current cellular applications of flow cytometry

Antioxidant Networks In vivo

Oxygen interacts with cells and can form highly reactive compounds in vivo known as reactive oxygen species (ROS). High levels of ROS can lead to cellular damage, oxidative stress, heart diseases and cancer. Known substances that are capable of halting the physiological process of oxidation in tissue are called antioxidants.This review covers developments in the field of antioxidant chemistry including interactions between antioxidants and ROS, topics about sources and natural occurrences, classification of antioxidants and a discussion of possible mechanisms. We also summarize examples of oxidative stress biomarkers.

Superhydrophobic surfaces as a source of airborne singlet oxygen through free space for photodynamic therapy

A superhydrophobic (SH) sandwich system has been developed to enable "contact-free" airborne singlet oxygen (1O2) delivery to a water droplet. The contact-free feature means that the sensitizer is physically separated from the droplet, which presents opportunities for photodynamic therapy (PDT). Trapping of airborne 1O2 in a H2O droplet residing on a lower SH surface was monitored with 9,10-anthracene dipropionate dianion by varying distances to an upper 1O2-generating surface. Short distances of 20 μm efficiently delivered airborne 1O2 to the droplet in single-digit picomolar steady-state concentrations. Delivery decreases linearly with distance, but 50% of the 1O2 steady-state concentration is trapped at a distance of 300 μm from the generating surface. The 1270 nm luminescence intensity was measured within the SH sandwich system, confirming the presence of airborne 1O2. Physical quenching of 1O2 to ground-state 3O2 by the water droplet itself and both physical and chemical quenching of 1O2 by the water droplet containing the trap 9,10-anthracene dipropionate dianion are observed. Unlike a majority of work in the field of PDT with dissolved sensitizers, where 1O2 diffuses short (hundreds of nanometers) distances, we show the delivery of airborne 1O2 via a superhydrophobic surface is effective through air in tenths of millimeters distances to oxidize an organic compound in water. Our results provide not only potential relevance to PDT but also surface bacterial inactivation processes.Fil: Aebisher, David. University Of Rzeszow; PoloniaFil: Bartusik-Aebisher, Dorota. University Of Rzeszow; PoloniaFil: Belh, Sarah J.. City University of New York; Estados UnidosFil: Ghosh, Goutam. City University of New York; Estados UnidosFil: Durantini, Andres Matías. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Liu, Yang. City University of New York; Estados UnidosFil: Xu, QianFeng. City University of New York; Estados UnidosFil: Lyons, Alan M.. City University of New York; Estados UnidosFil: Greer, Alexander. City University of New York; Estados Unido

Photosensitizer Drug Delivery via an Optical Fiber

: An optical fiber has been developed with a maneuverable miniprobe tip that sparges O2 gas and photodetaches pheophorbide (sensitizer) molecules. Singlet oxygen is produced at the probe tip surface which reacts with an alkene spacer group releasing sensitizer upon fragmentation of a dioxetane intermediate. Optimal sensitizer photorelease occurred when the probe tip was loaded with 60 nmol sensitizer, where crowding of the pheophorbide molecules and self-quenching were kept to a minimum. The fiber optic tip delivered pheophorbide molecules and singlet oxygen to discrete locations. The 60 nmol sensitizer was delivered into petrolatum; however, sensitizer release was less efficient in toluene-d8 (3.6 nmol) where most had remained adsorbed on the probe tip, even after the covalent alkene spacer bond had been broken. The results open the door to a new area of fiber optic-guided sensitizer delivery for the potential photodynamic therapy of hypoxic structures requiring cytotoxic control