Real Time Flow Control System for Precise Gas Feed in COIL

This paper reports development of a real time flow control system for precise, controlled and uniform gas feed to a flowing medium Chemical Oxygen Iodine Laser (COIL). The optimal operation of this prominent laser depends upon the desired supply of gas constituents such as nitrogen (N2), chlorine (Cl2) and iodine (I2) to achieve adequately mixed laser gas. The laser also demands real time variation of flow rates during gas constituent transitions in order to maintain stabilized pressures in critical subsystems. Diluent nitrogen utilized for singlet oxygen transport is termed as primary buffer gas and that for iodine transport is termed as secondary buffer gas (with main and bypass components). Also, nitrogen in precise flows is used for mirror blowing, nozzle curtain, cavity bleed and diffuser startup. A compact hybrid data acquisition system (Hybrid DAS) for precise flow control using LabVIEW 2014 platform has been developed. The supported flow ranges may vary from few mmole.s-1 to few hundred mmole.s-1. The estimated relative uncertainty in the largest gas component i.e. primary buffer gas feed is nearly 0.7%. The implementation of in-operation variation using flow ramp enables swift stabilization of singlet oxygen generator pressures critical for successful COIL operation. The performance of Hybrid DAS is at par with fully wired DAS providing the crucial benefit of remote field operation at distances of nearly 80m in line of sight and 35m with obstacles

THERAPEUTIC EFFECT OF SINGLET OXYGEN ADMINISTRATION ON CRYSTALLIZATION OF RATS’ BLOOD SERUM AT THERMAL TRAUMA

Biological and therapeutic effects of singlet oxygen have not been investigated yet. The aim of this paper is to estimate the influence of a short course (10 days) of singlet oxygen inhalations on crystallogenic properties of rats’ blood serum. The experiment was performed on 30 male Wistar rats, randomly divided into three equal groups. The first group was intact. The animals of the 2nd (control) and 3rd (test) groups under combined anesthesia were subjected to thermal trauma. Starting from the day following the injury, the rats of the test group inhaled daily the air flow from a singlet oxygen generator during 10 days. Blood samples were obtained from the rats of all groups. Dried samples were evaluated visually for crystallizability, structure index, facia destruction degree, and marginal zone clarity, using respective scales. It is stated that singlet oxygen inhalations facilitate the elimination of negative transformations in blood crystallization induced by thermal trauma. It indicates the positive rehabilitation potential.

Enhancing The Photocatalytic Conversion Of Pt(IV) Substrates By Flavoprotein Engineering

Our recent work demonstrates that certain flavoproteins can catalyze the redox activation of Pt(IV) prodrug complexes under light irradiation. Herein, we used site directed mutagenesis on the mini Singlet Oxygen Generator (mSOG) to modulate the photocatalytic activity of this flavoprotein towards two model Pt(IV) substrates. Among the prepared mutants, Q103V mSOG displayed enhanced catalytic efficiency as a result of its longer triplet excited state lifetime. This study shows, for the first time, that protein engineering can improve the catalytic capacity of a protein towards metal-containing substrate.

Enhancing The Photocatalytic Conversion Of Pt(IV) Substrates By Flavoprotein Engineering

Our recent work demonstrates that certain flavoproteins can catalyze the redox activation of Pt(IV) prodrug complexes under light irradiation. Herein, we used site directed mutagenesis on the mini Singlet Oxygen Generator (mSOG) to modulate the photocatalytic activity of this flavoprotein towards two model Pt(IV) substrates. Among the prepared mutants, Q103V mSOG displayed enhanced catalytic efficiency as a result of its longer triplet excited state lifetime. This study shows, for the first time, that protein engineering can improve the catalytic capacity of a protein towards metal-containing substrate.

A genetic probe for visualizing glutamatergic synapses and vesicles by 3D electron microscopy

Communication between neurons relies on the release of diverse neurotransmitters, which represent a key-defining feature of a neuron’s chemical and functional identity. Neurotransmitters are packaged into vesicles by specific vesicular transporters. However, tools for labeling and imaging synapses and synaptic vesicles based on their neurochemical identity remain limited. We developed a genetically encoded probe to identify glutamatergic synaptic vesicles at the levels of both light and electron microscopy (EM) by fusing the mini singlet oxygen generator (miniSOG) probe to an intra-lumenal loop of the vesicular glutamate transporter-2. We then used a 3D imaging method, serial block face scanning EM, combined with a deep learning approach for automatic segmentation of labeled synaptic vesicles to assess the subcellular distribution of transporter-defined vesicles at nanometer scale. These tools represent a new resource for accessing the subcellular structure and molecular machinery of neurotransmission and for transmitter-defined tracing of neuronal connectivity.

Bioengineering a light-responsive encapsulin nanoreactor: a potential tool for photodynamic therapy

Encapsulins, a prokaryotic class of self-assembling protein nanocompartments, are being re-engineered to serve as ‘nanoreactors’ for the augmentation or creation of key biochemical reactions. However, approaches that allow encapsulin nanoreactors to be functionally activated with spatial and temporal precision is lacking. We report the construction of a light-responsive encapsulin nanoreactor for “on-demand” production of reactive oxygen species (ROS). Herein, encapsulins were loaded with the fluorescent flavoprotein mini-Singlet Oxygen Generator (miniSOG), a biological photosensitizer that is activated by blue-light to generate ROS, primarily singlet oxygen (1O2). We established that the nanocompartments stably encased miniSOG, and in response to blue-light were able to mediate the photoconversion of molecular oxygen into ROS. Using an in vitro model of lung cancer, ROS generated by the nanoreactor was shown to trigger photosensitized oxidation reactions that exerted a toxic effect on tumour cells, suggesting utility in photodynamic therapy. This encapsulin nanoreactor thus represents a platform for the light-controlled initiation and/or modulation of ROS-driven processes in biomedicine and biotechnology.

Permanent Photodynamic Activation of the Cholecystokinin 2 Receptor

The cholecystokinin 2 receptor (CCK2R) is expressed in the central nervous system and peripheral tissues, playing an important role in higher nervous and gastrointestinal functions, pain sensation, and cancer growth. CCK2R is reversibly activated by cholecystokinin or gastrin, but whether it can be activated permanently is not known. In this work, we found that CCK2R expressed ectopically in CHO-K1 cells was permanently activated in the dark by sulfonated aluminum phthalocyanine (SALPC/AlPcS4, 10–1000 nM), as monitored by Fura-2 fluorescent calcium imaging. Permanent CCK2R activation was also observed with AlPcS2, but not PcS4. CCK2R previously exposed to SALPC (3 and 10 nM) was sensitized by subsequent light irradiation (>580 nm, 31.5 mW·cm−2). After the genetically encoded protein photosensitizer mini singlet oxygen generator (miniSOG) was fused to the N-terminus of CCK2R and expressed in CHO-K1 cells, light irradiation (450 nm, 85 mW·cm−2) activated in-frame CCK2R (miniSOG-CCK2R), permanently triggering persistent calcium oscillations blocked by the CCK2R antagonist YM 022 (30 nM). From these data, it is concluded that SALPC is a long-lasting CCK2R agonist in the dark, and CCK2R is photogenetically activated permanently with miniSOG as photosensitizer. These properties of SALPC and CCK2R could be used to study CCK2R physiology and possibly for pain and cancer therapies.