Biology subjects

Dasgupta, A. K.

Publications and source records attributed to Dasgupta, A. K..

7 recordsLinked to original sources

bioRxiv2018

Chelation therapy using static magnetic field

Static magnetic field (SMF) is reported to mimic chelation agents. In thalassemia blood, SMF minimizes iron overloading effect. In such cells ROS level is reduced, in presence of moderate strength (70mT). Pilot study on transfusion dependent thalassemia, thalassemia carriers and normal red blood clearly indicate the differential effects of SMF on thalassemia, thalassemia carrier and normal cells. SMF also reduces ROS induced DNA damage in lymphocytes. A comparative study on the iron chelating drug deferasirox and SMF treated lymphocytes further confirm our main thesis. This non-invasive therapeutic regime for hemochromatosis may serve the dual purpose of treating, iron overloading and minimizing, cellular damage by lowering the ROS level.

epidemiology↗

bioRxiv2017

Cross talk between photo-pigments and graphene electron cloud - Designing a biodiode

We report emergence of a new electrical material by growing photosynthetic biofilm on a Dirac material, graphene. The material showed new conducting as well as semiconducting properties. Frequency dependent capacitive spectra further indicated presence of electrical isosbestic points(at 0.8 and 9MHz), implying two state dieletric transitions at critical frequencies. A notable reult was a Schottky diode like behavior in the IV curve. Voltage dependent conductance with conductance peaks near the Schottky diode threshold was observed. We obtained facilitated growth of photosynthetic biofilm in presence of graphene. Lastly higher bacterial metabolism was seen in graphene incorporated biofilm. For this zero band gap Dirac material this can only be interpreted as coupling of the electron transport chain of the bacterial biofilm and the graphene electron cloud.

biophysics↗

bioRxiv2017

Antiferromagnetic switch in serum

1.Ferritin contains naturally occurring iron oxide nanoparticle surrounded by a structured spherical array of peptide residues that provides tremendous stability to this iron storage protein. We use synthetic citrate coated Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) and static magnetic field in exploring the Ferritin induced magnetic environment of human serum samples with varying ferritin level collected from thalassemic patients. We report anti-ferromagnetic properties of serum in patients with iron overloading. Magnetic pulling by an external magnetic field showed a cusp-like behavior with increasing concentration of serum Ferritin measured by standard ELISA based kit. A reduction in the extent of pulling after a threshold concentration of Ferritin (1500 ng/ml) suggests a Ferritin dependent magnetic switching.Negative magnetization (anti-ferromagnetization) was confirmed by Vibrating Sample Magnetometric (VSM) analysis of SPION-serum mixture containing very high level of Ferritin. Such magnetic switching may have a possible role in iron homeostasis during overloading of Ferritin.\n\n3. AbbreviationsSPIONs: Super Paramagnetic Iron Oxide Nanoparticles, VSM: Vibrating Sample Magnetometry, SQUID: Super conducting Quantum Interference Device, PCS: Photon Correlation Spectroscopy

biophysics↗

bioRxiv2017

Nitric oxide sensing by chlorophyll a

Nitric oxide (NO) acts as a signalling molecule that has direct and indirect regulatory roles in various functional processes in biology, though in plant kingdom its role is relatively unexplored. One reason for this is the fact that sensing of NO is always challenging. There are very few probes that can classify the different NO species. The present paper proposes a simple but straightforward way for sensing different NO species using chlorophyll, the source of inspiration being hemoglobin that serves as a NO sink in most mamalian system. The proposed method is able to classify NO from DETA-NONOate or (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl) amino] diazen-1-ium-1,2-diolate, nitrite, nitrate and S-nitrosothiol or SNO. This discrimination is carried out by chlorophyll a (chl a) at nano molar (nM) order of sensitivity and at 293K to 310K. Molecular docking reveals the differential binding behaviour of NO and SNO with chlorophyll, the predicted binding affinity matching with the experimental observation. Additional expreiments with diverse range of cyanobacteria reveals that apart from spectroscopic approach the proposed sensing module can be used in microscopic inspection of NO speices. Binding of NO is sensitive to tempertaure and static magnetic field. This provides additional support to the involvement of the porphyrin ring structure to the NO sensing process. This also broadens the scope of the sensing methods as hinted in the text.

bioengineering↗

bioRxiv2017

Light Amplification By Biofilm And Its Polarization Dependence

We report amplified, transmitted light intensity, compared to input, when photosynthetic biofilms were placed in the path of Rayleigh scattered, monochromatic light. Enhancement spectrum shows peak at around 505 nm, which corresponds to the pore wall thickness in biofilm ultra-structure, suggesting role of resonant Mie scattering. Enhancement factors differed when biofilms from different stages of growth were used. Enhancement factors were found to depend on the nature of Rayleigh scattering liquid. Polarizing Rayleigh scattered light by the use of polarizers affected the percentage of enhancement. Amplified output is achievable with constructive interference arising out of coherent forward light scattering, a theoretically predicted outcome of Anderson localization of photons. Possible uses of photosynthetic biofilms in organic material based photonic devices have been discussed.

bioengineering↗

bioRxiv2017

Bistability In Fluorescence From A Purple Non-Sulfur Bacteria

Bistable optical emission has been observed for photosynthetic purple non-sulfur bacteria Rhodobacter capsulatus SB1003. The microbes respond to UV excitation (at 395nm) in a bifurcating way one branch corresponding to increase and the other corresponding to diminishing fluorescent emission in the range 590-685nm.The switching between such bifurcating branches can be observed when parameters like concentration, temperature are varied or static magnetic field is applied. Thus switching from amplification to reduction occurs if fluorophore concentration lowered. Again if temperature is lowered a steady quenching (instead of amplification) of fluorescence is observed. However presence of magnetic field of the order of 0.5 T reverts this and once again the systems resumes its fluoresence amplifying state. We propose that aggregation of bacterial porphyrin and regulation of such aggregation by photon excitation may explain this bistablity. Possible ecological implication of the photosynthetic bistability is suggested.

systems biology↗

bioRxiv2017

Emerging Electrical Properties of Graphene incorporated Photosynthetic Biofilms

We report emergence of a new electrical material by growing photosynthetic biofilm on a Dirac material, graphene. The material showed new conducting as well as semiconducting properties. Frequency dependent capacitive spectra further indicated presence of electrical isosbestic points(at 0.8 and 9MHz), implying two state dieletric transitions at critical frequencies. A notable reult was a Schottky diode like behavior in the IV curve. Voltage dependent conductance with conductance peaks near the Schottky diode threshold was observed. We obtained facilitated growth of photosynthetic biofilm in presence of graphene. Lastly higher bacterial metabolism i was seen in the biofilm in contact with graphene as compared to its normal growth condition. For this zero band gap Dirac material this can only be interpreted as coupling of the electron transport chain of the bacterial biofilm and the graphene electron cloud.

biophysics↗