Education & Training

  • Ph.D 2015

    Biophysics

    Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, Japan.

  • M.Phil. 2011

    Material Science

    Department of Physics, Bangladesh University of Engineering and Technology (BUET)

  • MS 2005

    Biomedical Physics

    Department of Physics, University of Dhaka

  • B.Sc. (Hons.) 2003

    Physics

    Department of Physics, University of Dhaka

Honors, Awards and Grants

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Mechanism of Initial Stage of Pore Formation Induced by Antimicrobial Peptide Magainin 2

Moynul Hasan, Mohammad Abu Sayem Karal, Victor Levadnyy and Masahito Yamazaki

Abstract

Antimicrobial peptide magainin 2 forms pores in lipid bilayers, a property that is considered the main cause of its bactericidal activity. Recent data suggest that tension or stretching of the inner monolayer plays an important role in magainin 2-induced pore formation in lipid bilayers. Here, to elucidate the mechanism of magainin 2-induced pore formation, we investigated the effect on pore formation of asymmetric lipid distribution in two monolayers. First, we developed a method to prepare giant unilamellar vesicles (GUVs) composed of dioleoylphosphatidylglycerol (DOPG), dioleoylphosphatidylcholine (DOPC), and lyso-PC (LPC) in the inner monolayer and of DOPG/DOPC in the outer monolayer. We consider that in these GUVs, the lipid packing in the inner monolayer was larger than that in the outer monolayer. Next, we investigated the interaction of magainin 2 with these GUVs with an asymmetric distribution of LPC using the single GUV method, and found that the rate constant of magainin 2-induced pore formation, kp, decreased with increasing LPC concentration in the inner monolayer. We constructed a quantitative model of magainin 2-induced pore formation, whereby the binding of magainin 2 to the outer monolayer of a GUV induces stretching of the inner monolayer, causing pore formation. A theoretical equation defining kp as a function of magainin 2 surface concentration, X, reasonably explains the experimental relationship between kp and X. This model quantitatively explains the effect on kp of the LPC concentration in the inner monolayer. On the basis of these results, we discuss the mechanism of the initial stage of magainin 2-induced pore formation.

Experimental Estimation of Membrane Tension Induced by Osmotic Pressure

Sayed Ul Alam Shibly, Chiranjib Ghatak, Mohammad Abu Sayem Karal, Md. Moniruzzaman and Masahito Yamazaki

Abstract

Osmotic pressure (Π) induces the stretching of plasma membranes of cells or lipid membranes of vesicles, which plays various roles in physiological functions. However, there have been no experimental estimations of the membrane tension of vesicles upon exposure to Π. In this report, we estimated experimentally the lateral tension of the membranes of giant unilamellar vesicles (GUVs) when they were transferred into a hypotonic solution. First, we investigated the effect of Π on the rate constant, kp, of constant-tension (σex)-induced rupture of dioleoylphosphatidylcholine (DOPC)-GUVs using the method developed by us recently. We obtained the σex dependence of kp in GUVs under Π and by comparing this result with that in the absence of Π, we estimated the tension of the membrane due to Π at the swelling equilibrium, Math Eq. Next, we measured the volume change of DOPC-GUVs under small Π. The experimentally obtained values of Math Eq and the volume change agreed with their theoretical values within the limits of the experimental errors. Finally, we investigated the characteristics of the Π-induced pore formation in GUVs. The Math Eq corresponding to the threshold Π at which pore formation is induced is similar to the threshold tension of the σex-induced rupture. The time course of the radius change of GUVs in the Π-induced pore formation depends on the total membrane tension, σt; for small σt, the radius increased with time to an equilibrium one, which remained constant for a long time until pore formation, but for large σt, the radius increased with time and pore formation occurred before the swelling equilibrium was reached. Based on these results, we discussed the Math Eq and the Π-induced pore formation in lipid membranes.

Effects of Lipid Composition on the Entry of Cell-Penetrating Peptide Oligoarginine into Single Vesicles

Sabrina Sharmin, Md. Zahidul Islam, Mohammad Abu Sayem Karal, Sayed Ul Alam Shibly, Hideo Dohra and Masahito Yamazaki

Abstract

The cell-penetrating peptide R9, an oligoarginine comprising nine arginines, has been used to transport biological cargos into cells. However, the mechanisms underlying its translocation across membranes remain unclear. In this report, we investigated the entry of carboxyfluorescein (CF)-labeled R9 (CF-R9) into single giant unilamellar vesicles (GUVs) of various lipid compositions and the CF-R9-induced leakage of a fluorescent probe, Alexa Fluor 647 hydrazide (AF647), using a method developed recently by us. First, we investigated the interaction of CF-R9 with dioleoylphosphatidylglycerol (DOPG)/dioleoylphosphatidylcholine (DOPC) GUVs containing AF647 and small DOPG/DOPC vesicles. The fluorescence intensity of the GUV membrane due to CF-R9 (i.e., the rim intensity) increased with time to a steady-state value, and then the fluorescence intensity of the membranes of the small vesicles in the GUV lumen increased without leakage of AF647. This result indicates that CF-R9 entered the GUV lumen from the outside by translocating across the lipid membrane without forming pores through which AF647 could leak. The fraction of entry of CF-R9 at 6 min in the absence of pore formation, Pentry (6 min), increased with an increase in CF-R9 concentration, but the CF-R9 concentration in the lumen was low. We obtained similar results for dilauroyl-PG (DLPG)/ditridecanoyl-PC (DTPC) (2/8) GUVs. The values of Pentry (6 min) of CF-R9 for DLPG/DTPC (2/8) GUVs were larger than those obtained with DOPG/DOPC (2/8) GUVs at the same CF-R9 concentrations. In contrast, a high concentration of CF-R9 induced pores in DLPG/DTPC (4/6) GUVs through which CF-R9 entered the GUV lumen, so the CF-R9 concentration in the lumen was higher. However, CF-R9 could not enter DOPG/DOPC/cholesterol (2/6/4) GUVs. Analysis of the rim intensity showed that CF-R9 was located only in the outer monolayer of the DOPG/DOPC/cholesterol (2/6/4) GUVs. On the basis of analyses of these results, we discuss the elementary processes by which CF-R9 enters GUVs of various lipid compositions.

Analysis of constant tension-induced rupture of lipid membranes using activation energy

Mohammad Abu Sayem Karal, Victor Levadnyy and Masahito Yamazaki

Abstract

The stretching of biomembranes and lipid membranes plays important roles in various physiological and physicochemical phenomena. Here we analyzed the rate constant kp of constant tension-induced rupture of giant unilamellar vesicles (GUVs) as a function of tension σ using their activation energy Ua. To determine the values of kp, we applied constant tension to a GUV membrane using the micropipette aspiration method and observed the rupture of GUVs, and then analyzed these data statistically. First, we investigated the temperature dependence of kp for GUVs of charged lipid membranes composed of negatively charged dioleoylphosphatidylglycerol (DOPG) and electrically neutral dioleoylphosphatidylcholine (DOPC). By analyzing this result, the values of Ua of tension-induced rupture of DOPG/DOPC-GUVs were obtained. Ua decreased with an increase in σ, supporting the classical theory of tension-induced pore formation. The analysis of the relationship between Ua and σ using the theory on the electrostatic interaction effects on the tension-induced rupture of GUVs provided the equation of Ua including electrostatic interaction effects, which well fits the experimental data of the tension dependence of Ua. A constant which does not depend on tension, U0, was also found to contribute significantly to Ua. The Arrhenius equations for kp using the equation of Ua and the parameters determined by the above analysis fit well to the experimental data of the tension dependence of kp for DOPG/DOPC-GUVs as well as for DOPC-GUVs. On the basis of these results, we discussed the possible elementary processes underlying the tension-induced rupture of GUVs of lipid membranes. These results indicate that the Arrhenius equation using the experimentally determined Ua is useful in the analysis of tension-induced rupture of GUVs.

Communication: Activation energy of tension-induced pore formation in lipid membranes

Mohammad Abu Sayem Karal and Masahito Yamazaki

Abstract

Tension plays a vital role in pore formation in biomembranes, but the mechanism of pore formation remains unclear. We investigated the temperature dependence of the rate constant of constant tension (σ)–induced pore formation in giant unilamellar vesicles of lipid membranes using an experimental method we developed. By analyzing this result, we determined the activation energy (Ua) of tension-induced pore formation as a function of tension. A constant (U0) that does not depend on tension was found to contribute significantly to Ua. Analysis of the activation energy clearly indicated that the dependence of Ua on σ in the classical theory is correct, but that the classical theory of pore formation is not entirely correct due to the presence of U0. We can reasonably consider that U0 is a nucleation free energy to form a hydrophilic pre-pore from a hydrophobic pre-pore or a region with lower lateral lipid density. After obtaining U0, the evolution of a pre-pore follows a classical theory. Our data provide valuable information that help explain the mechanism of tension-induced pore formation in biomembranes and lipid membranes.

Electrostatic interaction effects on tension-induced pore formation in lipid membranes

Mohammad Abu Sayem Karal, Victor Levadnyy, Taka-aki Tsuboi, Marina Belaya, and Masahito Yamazaki

Abstract

We investigated the effects of electrostatic interactions on the rate constant (kp) for tension-induced pore formation in lipid membranes of giant unilamellar vesicles under constant applied tension. A decrease in salt concentration in solution as well as an increase in surface charge density of the membranes increased kp. These data indicate that kp increases as the extent of electrostatic interaction increases. We developed a theory on the effect of the electrostatic interactions on the free energy profile of the membrane containing a prepore and also on the values of kp; this theory explains the experimental results and fits the experimental data reasonably well in the presence of weak electrostatic interactions. Based on these results, we conclude that a decrease in the free energy barrier of the prepore state due to electrostatic interactions is the main factor causing an increase in kp.

Stretch-Activated Pore of the Antimicrobial Peptide, Magainin 2

Mohammad Abu Sayem Karal, Jahangir Md. Alam, Tomoki Takahashi, Victor Levadny and Masahito Yamazaki

Abstract

Antimicrobial peptide magainin 2 forms pores in lipid membranes and induces membrane permeation of the cellular contents. Although this permeation is likely the main cause of its bactericidal activity, the mechanism of pore formation remains poorly understood. We therefore investigated in detail the interaction of magainin 2 with lipid membranes using single giant unilamellar vesicles (GUVs). The binding of magainin 2 to the lipid membrane of GUVs increased the fractional change in the area of the membrane, δ, which was proportional to the surface concentration of magainin 2, X. This indicates that the rate constant of the magainin 2-induced two-state transition from the intact state to the pore state greatly increased with an increase in δ. The tension of a lipid membrane following aspiration of a GUV also activated magainin 2-induced pore formation. To reveal the location of magainin 2, the interaction of carboxyfluorescein (CF)-labeled magainin 2 (CF-magainin 2) with single GUVs containing a water-soluble fluorescent probe, AF647, was investigated using confocal microscopy. In the absence of tension due to aspiration, after the interaction of magainin 2 the fluorescence intensity of the GUV rim due to CF-magainin 2 increased rapidly to a steady value, which remained constant for a long time, and at 4–32 s before the start of leakage of AF647 the rim intensity began to increase rapidly to another steady value. In contrast, in the presence of the tension, no increase in rim intensity just before the start of leakage was observed. These results indicate that magainin 2 cannot translocate from the outer to the inner monolayer until just before pore formation. Based on these results, we conclude that a magainin 2-induced pore is a stretch-activated pore and the stretch of the inner monolayer is a main driving force of the pore formation.

CHARACTERIZATION OF AMORPHOUS Fe69V6P15C10 METALLIC ALLOY

M. A. S. Karal, M. Kamruzzaman, D. K. Saha and F. A. Khan

Abstract

Fe69V6P15C10 amorphous metallic alloy was prepared by the standard melt spinning technique and characterize their structural, transport, thermal and magnetic properties. The composition of the as prepared alloy was confirmed by energy dispersive X-ray (EDX) and the surface morphology was carried out by scanning electron microscopy (SEM). The structure of the as prepared and annealed sample was studied by X-ray diffraction (XRD). The XRD patterns of annealed sample shows that contain a BCC structure for temperatures between 400ºC and 450ºC and a hexagonal structure for temperatures between 500ºC and 650ºC. The grain size of the sample is found to vary from 20 to 53 nm. Hall resistivity and magnetoresistance (MR) was measured using four-probe technique. Resistivity remains constant upto 400ºC and then decreases with the increase of temperature. The crystallization behavior of the sample was performed by differential thermal analysis (DTA). Magnetization was measured by using vibrating sample magnetometer (VSM) at room temperature and the measured value of the saturation magnetization was 82.6 emu/g. Both the magnitude of impedance and phase angle remained constant upto 10 MHz and then remarkably increased with frequency.

The single GUV method for revealing the functions of antimicrobial, pore-forming toxin, and cell-penetrating peptides or proteins

Md. Zahidul Islam, Jahangir Md. Alam, Yukihiro Tamba, Mohammad Abu Sayem Karala and Masahito Yamazaki

Abstract

We recently developed the single giant unilamellar vesicle (GUV) method for investigating the functions and dynamics of biomembranes. The single GUV method can provide detailed information on the elementary processes of physiological phenomena in biomembranes, such as their rate constants. Here we describe the process of pore formation induced by the antimicrobial peptide (AMP), magainin 2, and the pore-forming toxin (PFT), lysenin, as revealed by the single GUV method. We obtained the rate constants of several elementary steps, such as peptide/protein-induced pore formation in lipid membranes and the membrane permeation of fluorescent probes through the pores. Information on the entry of the cell-penetrating peptide (CPP), transportan 10 (TP10), into a single GUV and its induced pore formation in lipid membranes was also obtained. We compare the single GUV method with other methods for investigating the interaction of peptides/proteins with lipid membranes (i.e., the large unilamellar vesicle (LUV) suspension method, the GUV suspension method, and single channel recording), and discuss the pros and cons of the single GUV method. On the basis of these data, we discuss the advantages of the single GUV method.

Crystallization, Transport and Magnetic Properties of the Amorphous (Fe1–xMnx)75P15C10 Alloys

Md. Kamruzzaman, Md. Abu Sayem Karal, Dilip Kumar Saha, Feroz Alam Khan

Abstract

The amorphous (Fe1-xMnx)75P15C10 (0 ≤ x ≥ 0.30) alloys were prepared by the standard melt spinning technique and investigated their crystallization, thermal, transport and magnetic properties. Crystallization was observed from 400℃ to 650℃ with an interval 50℃within 30 minutes annealing time by XRD. The as-cast samples were amorphous in nature. Annealing 400℃ to 450℃ samples showed the mixed bcc Fe and amorphous structures. The lattice parameter ‘a’ was varied from 2.855 to 2.859 ? but above 450℃, samples contained hexagonal, FeP and FeC structures. The lattice parameters ‘a’ and ‘c’ were varied from (5.016-5.036) ? and (13.575-13.820) ? , respectively. Average crystallite size was found to vary from 8 to 48 nm. Crystallization temperature and weight change were observed by differential thermal analysis and thermogravimetric analysis, respectively. Crystallization temperature was increased with increasing Mn content. Resistivity was increased above and bellows the Curie temperature. Real permeability remained almost constant upto around 106 Hz for of all samples after that it was decreased with increasing frequency and it was also decreased with Mn, whereas imaginary permeability was increased sharply above frequency 107 Hz. The value of saturation magnetization was found to decrease with increment Mn.

TRANSPORT AND MAGNETIC PROPERTIES OF (Fe100-xVx)75 P15C10AMORPHOUS ALLOYS

M.A.S. KARAL, M. KAMRUZZAMAN AND F.A. KHAN

Abstract

(Fe100-xVx)75P15C10 (x=0, 5, 10 and 15) amorphous alloys in the form of ribbon were prepared by the standard melt spinning technique and studied their transport and magnetic properties. The resistivity follows ‘Mooij correlation’ at low temperature (300-93)K. The Hall resistivity and the magnetoresistance (MR) were measured in an applied magnetic field upto 0.6T at room temperature (RT=300 K). Anomalous Hall effect was observed in the Hall resistivity measurement and MR was found to vary 0-8%. The saturation magnetization gradually decreasedwith the increase of V in the alloys at RT.

TRANSPORT, MAGNETIC AND THERMAL PROPERTIES OF (Fe100-XVX)75 P15C10 SEMI-AMORPHOUS RIBBONS

M.A.S. KARAL, M. KAMRUZZAMAN, M.G.M. HOSSAIN, H.M.I. JAIM and F.A. KHAN

Abstract

(Fe100-xVx)75P15C10[x=1.5, 3, 9 and 15] semi-amorphous alloys (partially crystalline) in the form of ribbon were prepared by the standard melt spinning technique and studied their transport, magnetic and thermal properties. The nature of the as prepared samples was studied by x-ray diffraction (XRD). The resistivity of the samples was investigated fromtemperature 93K to 800 K. The resistivity followed ‘Mooij Correlation’ at low temperature (93 K-300 K). The resistivity athigher temperature (300 K-800 K) remained constant upto a certain temperature and then decreased with temperature rise. The Hall resistivity and the magnetoresistance (MR) were measured in an applied magnetic field upto 0.6 T at room temperature (RT=300 K). Anomalous Hall effect was observed in the Hall resistivity measurement and MR was found to vary 0-8%. The saturation magnetization gradually decreases with the increase of the substitution of Fe by Vat RT. Both the impedance magnitude and phase angle remained constant upto 106 Hz and then remarkably increased with frequency. The thermal properties associated with crystallization temperature and weight changes were measured by using the differential thermal analyzer (DTA) and the thermo gravimetric (TG) techniques respectively.

Sensitivity of Four-electrode Focused Impedance Measurement (FIM) system for objects with different conductivity

M A S Karal, K S Rabbani

Abstract

This work presents the results of an empirical study of the sensitivity of a four-electrode FIM
technique developed by us earlier, for objects of different conductivity. FIM has potential for the
characterization of biological tissue in physiological study and diagnosis. Experimental
measurements were performed on a 2D phantom made up of saline with a focused square zone at the
centre. Three cylindrical objects of different conductivities (an insulator, a conductor, and a piece of
potato offering an intermediate conductivity) were used for the sensitivity measurements. Adjacent
square zones had sensitivities of about 22% of that at the center for the insulator, about 13% for the
conductor and about 10% for potato, showing a better focusing in the last case. The outer locations
had negligible sensitivities. Inverse (negative) sensitivity, which is unavoidable in tetrapolar
impedance measurements, was small and negligible in all the cases. Degree of perturbation of
equipotential lines has been suggested to be the cause of the above differences in focusing, less
perturbation giving rise to better focusing, which would apply for most biological objects to be
studied using FIM.

SYNTHESIS AND CHARACTERIZATION OF Zn1-x-yCdxLiyOδ SOLID SOLUTION

M. KAMRUZZAMAN, M. K. R. KHAN, M. M. RAHMAN2, M. A. S. KARAL1M. SHAHJAHAN and M. G. M. CHOWDHURY

Abstract

Zn1-x-yCdxLiyOδ (x=0.30; y=0.05, 0.10, 0.15, 0.20 and δ= 0.975, 0.95, 0.925, 0.90)samples have been prepared byconventional solid state reaction method and studied their electrical, magnetic and structural properties. The dc electrical resistivity measurement shows that all samples are highly resistive (~106 ohm-cm) upto a transition temperature (Tt), above which resistivity falls drastically that reveals the samples are semiconducting in nature and Ttdecreases with increase of Li. The activation energies vary from (0.74-0.51) eV depending on doping concentrations, i.e. the activation energy is lower for higher concentration of Li in the solution. Magnetic mass susceptibility measurement shows negative sign that indicate the samples are diamagnetic. From XRD analysis, there exist two phases one is hexagonal ZnO and another is cubic CdO which suggests the formation of superlattice structure of the system. Crystallite size at planes (100), (002), (101), (102), (110), (103), (200), (112) and (111), (200), (220) for ZnO and CdOranges from 20 to 50 nm and for Li ranges from 27 to 40 nm.

Structural and Dielectric Properties of Zn1-x-yCdxLiyO Solid Solution

M Kamruzzaman, MKR Khan, MM Rahman, M Shahjahan and MAS Karal

Abstract

Zn1-x-yCdxLiyO (x=0.30 and y=0.05, 0.10, 0.15, 0.20) have been prepared by solid state reaction method. The prepared samples have been characterized by structural and dielectric measurements. X-ray diffraction (XRD) patterns show a good crystalline nature having double crystal structure and indicates the phase mixing of the constituent components. The hexagonal phase corresponding to ZnO and cubic phase to CdO is well defined and the lattice parameters are consistent with the published values (Grant in Aid report 1987). The estimated lattice parameters, bond length and crystallite size are quite consistent corresponding to the hexagonal ZnO and cubic CdO which suggests the formation of super lattice structure of the system. Crystallite size at different crystallographic planes analyzed from XRD for both ZnO and CdO lie between (15-50) nm. The variation of the dielectric constant of the samples with frequency is systematic and the dielectric constant increases with the increase of Li in the solution.

Variation of Sensitivity Within the Focused Zone of the New Four-Electrode Focused Impedance Measurement (FIM) System

K. S. Rabbani and M. A. S. Karal

Abstract

A New Four-Electrode Focused Impedance Measurement (FIM) System for Physiological Study

K. S. Rabbani, M. A. S. Karal

Abstract

A recently developed Focused Impedance Measurement (FIM) system (by the authors’ group) uses six electrodes to localize a zone of interest. Because of 3D sensitivity it could give physiological information on large organs like stomach, lungs, etc. using surface electrodes in the frontal plane. This paper presents a modified FIM technique using four electrodes placed at the corners of a square matrix. Firstly current is driven through an adjacent electrode pair while the potential is measured across the opposite pair from which an impedance value is obtained. Then a similar measurement is made at 90° to the above by changing connections to the electrode pairs appropriately. The sum of these two impedance values has a dominant contribution from the central region within the square matrix, giving the desired focusing. Experimental sensitivity maps obtained from a 2D phantom have verified the focusing effect. Compared to the previous six-electrode FIM system the focusing effect is slightly less, but this new technique has less negative artifacts in the periphery. This new FIM method can be applied both in the frontal plane and in the transverse plane of the human thorax, giving a further advantage besides requiring fewer electrodes.

Molecular Diffusion through a Peptide-Induced Nano Sized Pore in the Membrane of Vesicle Using COMSOL Simulation

Md. Kamrul Islam, Mohammad Abu Sayem Karal and Md. Kabir Ahamed

Abstract

Effects of Salt Concentrations and Surface Charge Density on the Size Distribution and Average Size of Giant Unilamellar Vesicles

Marzuk Ahmed, Mohammad Abu Sayem Karal, Md. Kabir Ahamed and Md. Mostafizur Rahman

Abstract

Development of Irreversible Electroporation (IRE) Technique for the Investigations of Rupture of Giant Unilamellar Vesicles

Md. Kabir Ahamed, Mehedi Hasan, Mohammad Abu Sayem Karal, Md. Mostafizur Rahman, Md. Marzuk Ahmed, and Md. Mostofa Shakil

Abstract

Development of a Low Cost Technique for the Purification of Vesicles Working Without Electricity and Electromechanical Devices

Mostafizur Rahman, Mohammad Abu Sayem Karal, Md. Kabir Ahamed, Marzuk Ahmed, and Md. Mostofa Shakil

Abstract

Biosynthesis of Magnetic Nanoparticles and Investigations Its Interactions with Lipid Membranes of Vesicles

Shareef Ahammed, Md. Mostofa Shakil, Mohammad Abu Sayem Karal, Md. Kabir Ahamed, Md. Mostafizur Rahman, Md. Marzuk Ahmed, Md. Mehedi Hasan, and Mohammad Moniruzzaman

Abstract

Effect of head bending on peripheral nerves-observed using EMG and MRI technique

Sabrina Sharmin, Zaid Bin Mahbub, Mohammad Abu Sayem Karal, and K Siddique-e Rabbani

Abstract

Irreversible Electroporation (IRE) Technique for the Study of Pore Formation in the Lipid Membranes of Giant Unilamellar Vesicles (GUVs)

M. K. Ahamed, M. A. S. Karal, M. M. Ahmed, M. M. Rahman, M. Hasan, M. M. Shakil, M. N. Alam and M. S. Islam

Abstract

Edge Detection of Peptide-Induced Submicron Pores in the Lipid Membranes through ImageJ

M. K. Ahamed, M. A. S. Karal, M. M. Shakil, M. Ahmed, M. Rahman, M. M. Hasan, M. N. Alam, and S. U. A. Shibly

Abstract

Effects of Electrostatic Interaction on the Sizes of Giant Unilamellar Vesicles (GUVs)

M. Ahmed, M. A. S. Karal, M. K. Ahamed, M. M. Rahman, M. Shakil, and M. N. Alam

Abstract

Non-Electromechanical Technique for the Purification of Giant Unilamellar Vesicles (GUVs)

M. Rahman, M. A. S. Karal, M. K. Ahamed, M. Ahmed, M. M. Shakil, M. N. Alam, M. M. Hasan, and S. Ahammed

Abstract

Molecular Transport through a Nano-sized Pore in the Model Membranes Using COMSOL Multiphysics

M. K. Islam, M. A. S. Karal, M. K. Ahamed, and S. K. Roy

Abstract

Synthesis of Lipid Membranes of Giant Unilamellar Vesicles (GUVs) of and its Interactions with Magnetic Nanoparticles

M. M. Shakil, M. A. S. Karal, S. Ahammed, M. M. Hasan, M. N. Alam, M. Moniruzzaman, and M. K. Islam

Abstract

Biocompatible Leaf Extracts Mediated Synthesis, Characterization and Antibacterial Application of Magnetite Nanoparticles

M. Moniruzzaman, M. A. S. Karal, M. N. I. Khan, A. K. M. A. Ullah, and S. Ahammed

Abstract

A New Six-Electrode Electrical Impedance Technique for Probing the Deep Tissue Organ of the Human Body

S. K. Roy, M. A. S. Karal, M. A. Kadir, and K. Siddique-e-Rabbani

Abstract

A Comparative Study on Antibiotic-Induced Killing of Bacteria

Md. Mostofa Shakil, Md. Abu Jubayer Hossain, Mohammad Abu Sayem Karal, and Jahangir Md. Alam

Abstract

A Novel Six Electrode System for Probing Deep Tissue Organ by Electrical Impedance Technique

Shamor Kanti Roy, Mohammad Abu Sayem Karal, Muhammad Abdul Kadir, K. Siddique-e-Rabbani

Abstract

A Facial Synthesis of Magnetite Nanoparticles Using Ipomoea aquatica Aqueous Extract and Its Anti-Bacterial Activity

Mohammad Moniruzzaman, Mohammad Abu Sayem Karal, A. K. M. Atique Ullah, Mohammad Nazrul Islam Khan

Abstract

Synthesis and Observations of Giant Unilamellar Vesicles (GUVs) of Lipid Membranes

Mohammad Abu Sayem Karal, Md. Mostofa Shakil, Md. Mehedi Hasan, Marzuk Ahmed, Mostafizur Rahman, Md. Kabir Ahamed, and Md. Sayful Islam

Abstract

Probing Deep Tissue Organ by Electrical Impedance Technique

Shamor Kanti Roy, Mohammad Abu Sayem Karal, K Siddique-e-Rabbani, Muhammad Abdul Kadir

Abstract

Leaf Extract Mediate Synthesis of Magnetite Nanoparticles and its Characterization for Antibacterial Applications

Mohammad Moniruzzaman, Mohammad Abu Sayem Karal, Mohammed Nazrul Islam Khan, A. K. M. Atique Ullah

Abstract

Effect of Asymmetric Packing of Lipids in Outer and Inner Monolayer on Magainin 2-Induced Pore Formation in Lipid Bilayer

Moynul Hasan, Mohammad Abu Sayem Karal, Victor Levadny, Masahito Yamazaki

Abstract

Effect of Asymmetric Packing of Lipids in Outer and Inner Monolayer on Magainin 2-Induced Pore Formation in Lipid Bilayer

Moynul Hasan, Mohammad Abu Sayem Karal, Victor Levadny, Masahito Yamazaki

Abstract

Elementary processes of antimicrobial peptide magainin 2-induced pore formation and its mechanism

Mohammad Abu Sayem Karal, Md. Jahangir Alam, Moynul Hasan, Victor Levadny, Masahito Yamazaki

Abstract

Effect of lipid composition on the entry of cell-penetrating peptide oligoarginine (Rn) into single vesicles

Sabrina Sharmin, Md. Zahidul Islam, Mohammad Abu Sayem Karal, Sayed Ul Alam Shibly, and Masahito Yamazaki

Abstract

Elucidation of mechanism of the effects of constant tension-induced rupture formation in giant unilamellar vesicles (GUVs) of lipid membranes using activation energy

Mohammad Abu Sayem Karal, Victor Levadny, and Masahito Yamazaki

Abstract

Antimicrobial peptide magainin 2-induced leakage from single E.

Jahangir Md. Alam, Md. Moniruzzaman, Parliza parez, Md. Mostofa Shakil, Md. Abu Jubayer Hossain, Md. Zohurul Islam, Md, Sadrul Hasan Chowdhury, Md. Anwarul Haque, Mohammad Abu Sayem Karal, and Masahito Yamazaki

Abstract

A biophysical approach for investigation of the antibiotic-induced bacterial killing mechanism using E. coli

Md. Mostofa Shakil, Md. Abu Jubayer Hossain, Md. Zohurul Islam, Md.Sadrul Hasan Chowdhury, Hossain Md. Faruquee, Md. Anwarul Haque, Masahito Yamazaki, Mohammad Abu Sayem Karal, and Jahangir Md. Alam

Abstract

Effects of mechanical property of lipid membranes on the entry of cell-penetrating peptide oligoarginine into a single vesicle

Sabrina Sharmin, Md. Zahidul Islam, Mohammad Abu Sayem Karal, Shibly Sayed Ul Alam, Hideo Dohra, and Masahito Yamazaki

Abstract

Effects of lipid composition on the entry of cell-penetrating peptide oligoarginine (Rn) into single vesicles

Sabrina Sharmin, Md. Zahidul Islam, Mohammad Abu Sayem Karal, Shibly Sayed Ul Alam, Hideo Dohra, and Masahito Yamazaki

Abstract

A Mechanism of Antimicrobial Peptide, Magainin 2-Induced Pore Formation in Lipid Membranes

Moynul Hasan, Mohammad Abu Sayem Karal, Victor Levadny, Md. Zahidul Islam, Masahito Yamazaki

Abstract

Effects of lipid compositions on the entry of cell-penetrating peptide oligoarginine into single vesicles

Sabrina Sharmin, Md. Zahidul Islam, Mohammad Abu Sayem Karal, Sayed Ul Alam Shibly and Masahito Yamazaki

Abstract

Effects of lipid composition on the entry of cell-penetrating peptide oligoarginine (Rn) into single vesicles

Sabrina Sharmin, Md. Zahidul Islam, Mohammad Abu Sayem Karal, Shibly Sayed Ul Alam, Hideo Dohra, and Masahito Yamazaki

Abstract

Experimental Estimation of Membrane Tension Induced by Osmotic Pressure

Sayed Ul Alam Shibly, Chiranjib Ghatak, Mohammad Abu Sayem Karal, Md. Moniruzzaman, and Masahito Yamazaki

Abstract

Investigation of Constant Tension-Induced Rupture in Lipid Membranes Using Activation Energy

Mohammad Abu Sayem Karal, Victor Levadny, and Masahito Yamazaki

Abstract

Activation Energy of Tension-Induced Pore Formation in Lipid Membranes

Mohammad Abu Sayem Karal, and Masahito Yamazaki

Abstract

Analysis of Constant Tension-Induced Rupture in Lipid Membranes Using Activation Energy

Mohammad Abu Sayem Karal, Victor Levadny, and Masahito Yamazaki

Abstract

Synthesis and Characterization of Bi1-xYxFe0.7Mn0.3O3 Ceramics

S. K. Saha, M. A. Hossain, P. Biswas, M. A. S. Karal and A. K. M. Akther Hossain

Abstract

Effects of Gd on Cr Doped Multiferroic BiFeO3 Ceramics

M. A. Hossain, M. A. U. Islam, M. A. S. Karal and A. K. M. Akther Hossain

Abstract

Structural, Magnetic and Dielectric Properties of Polycrystalline La0.70Ca0.10+xSr0.20-xMnO3

N. Bushra, S. Hussain, M. A. S. Karal and A. K. M Akther Hossain

Abstract

Structural and Magnetic Properties of Mn Substituted Nanocrystalline Nicuzn Ferrites

A. Ahad, M. A. S. Karal and A. K.M. Akther Hossain

Abstract

Synthesis and Characterization of Zn Substituted Li-Ni Ferrites

M. A. Islam, M. A. Hossain, M. A. S. Karal and A. K. M. Akther Hossain

Abstract

Influence of Li1+ Substitution on Impedance Spectroscopy and Electric Modulus Studies of LixCu0.10Co0.1Zn0.8-2xFe2+XO4

R. Parvin, M. A. S. Karal and A. K. M. Akther Hossain

Abstract

Measurement of the Activation Energy of Tension-Induced Pore Formation in Giant Unilamellar Vesicles of Lipid Membranes

Mohammad Abu Sayem Karal, Victor Levadny, and Masahito Yamazaki

Abstract

Activation Energy of the Tension-Induced Pore Formation in Lipid Membranes

Mohammad Abu Sayem Karal, and Masahito Yamazaki

Abstract

Effects of Line Tension on Antimicrobial Peptide Magainin 2-Induced Pore Formation

Jahangir Md. Alam, Mohammad Abu Sayem Karal, Victor Levadny, and Masahito Yamazaki

Abstract

Effect of Osmotic Pressure on Constant Tension-Induced Pore Formation in Lipid Membranes

Sayed Shibly Ul Alam, Mohammad Abu Sayem Karal, and Masahito Yamazaki

Abstract

Electrostatic Effects on Tension-Induced Pore Formation in Lipid Membranes

Mohammad Abu Sayem Karal, Victor Levadny, Taka-aki Tsuboi, Marina Belaya, and Masahito Yamazaki

Abstract

Electrostatic Effects on Tension-Induced Pore Formation in Lipid Membranes

Mohammad Abu Sayem Karal, Victor Levadny, Taka-akiTsuboi, Marina Belaya, and Masahito Yamazaki

Abstract

Elucidation of the Mechanism of Pore formation of the Antimicrobial peptide, Magainin 2 using Single GUVs

Md. Jahangir Alam, Mohammad Abu Sayem Karal, Tomoki Takahashi, Victor Levadny, and Masahito Yamazaki

Abstract

Electrostatic Effects on Tension-Induced Pore Formation in Lipid Membranes

Mohammad Abu Sayem Karal, Victor Levadny, Taka-akiTsuboi, Marina Belaya, and Masahito Yamazaki

Abstract

Stretch-Activated Pore in Antimicrobial Peptide, Maganin 2

Md. Jahangir Alam, Mohammad Abu Sayem Karal, Tomoki Takahashi, Victor Levadny, and Masahito Yamazaki

Abstract

Elucidation of the Mechanism of Pore formation of the Antimicrobial peptide, Magainin 2 using Single GUVs

Md. Jahangir Alam, Mohammad Abu Sayem Karal, Tomoki Takahashi, Victor Levadny, and Masahito Yamazaki

Abstract

Theory on the electrostatic effects on tension-induced pore formation in lipid membranes

Victor Levadny, Mohammad Abu Sayem Karal, Taka-akiTsuboi, Marina Belaya, and Masahito Yamazaki

Abstract

Stretch-Activated Pore in Antimicrobial Peptide, Maganin 2

Md. Jahangir Alam, Mohammad Abu Sayem Karal, Tomoki Takahashi, Victor Levadny, and Masahito Yamazaki

Abstract

Effects of electrostatic interactions on the rate constant of tension-induced pore formation in lipid membranes

Mohammad Abu Sayem Karal, Taka-akiTsuboi, Victor Levadny, and Masahito Yamazaki

Abstract

Effects of tension on entry of cell-penetrating peptide transportan 10 into a single vesicles and its pore formation in lipid membranes

Md. Zahidul Islam, Mohammad Abu Sayem Karal, and Masahito Yamazaki

Abstract

Effects of electrostatic interactions on tension-induced pore formation in single GUVs

Taka-akiTsuboi, Mohammad Abu Sayem Karal, Victor Levadny, Marina Belaya, and Masahito Yamazaki

Abstract

Stretch-Activated Pore in Antimicrobial Peptide, Maganin 2

Mohammad Abu Sayem Karal, Jahangir MdAlam, Tomoki Takahashi, Victor Levadny, and Masahito Yamazaki

Abstract

The Single GUV method for Probing Elementary Processes of Peptide/Proteins-Induced Pore Formation in Biomembranes

Jahangir Md. Alam, Md. Zahidul Islam, Taka-aki Tsuboi, Mohammad Abu Sayem Karal, and Masahito Yamazaki

Abstract

Effect of Electrostatic Interactions on Tension-Induced Pore Formation in Single GUVs

Mohammad Abu Sayem Karal, Taka-aki Tsuboi, Victor Levadny, Marina Belaya, and Masahito Yamazaki

Abstract

Rate Constants of Tension-Induced Pore Formation in Lipid Membranes

Taka-aki Tsuboi, Mohammad Abu Sayem Karal, Victor Levadny, Marina Belaya, and Masahito Yamazaki

Abstract

Effects of Electrostatic Interactions on Rate Constants of Tension-Induced Pore Formation in Single GUVs

Taka-akiTsuboi, Mohammad Abu Sayem Karal, Victor Levadny, and Masahito Yamazaki

Abstract

Effects of Mechanical Properties of Lipid Membranes on Antimicrobial Peptide Magainin 2-Induced Pore Formation

Mohammad Abu Sayem Karal, Taka-akiTsuboi, Jahangir MdAlam, Md. Zahidul Islam, and Masahito Yamazaki

Abstract

Transport properties of Fe63.75V11.25P15C10

M. A. S. Karal, and F. A. Khan

Abstract

Crystallization phenomenon and magnetic properties of the amorphous (Fe(1-x)Mnx)75P15C10 alloya

M. Kamruzzaman, M. A. S. Karal, D. K. Saha, and F. A. Khan

Abstract

Characterization of amorphous Fe69V6P15C10 metallic alloys

M. A. S. Karal, M. Kamruzzaman, D. K. Saha, and F. A. Khan

Abstract

Structural, thermal and magnetic properties of (Fe(1-x)Mnx)75P15C10 alloys

M. Kamruzzaman, M. A. S. Karal, D. K. Saha, and F. A. Khan

Abstract

AC Properties of Mn0.5Zn0.5Fe2O4

H. M. Iftekhar Jaim, M. A. S. Karal, M. Kamruzzaman and F. A. Khan

Abstract

Transport and magnetic properties of (Fe0.70Mn0.30)0.75P0.15C0.10 alloy

M. Kamruzzaman, M. A. S. Karal, H. M. Iftekhar Jaim, F. A. Khan

Abstract

Resistivity, Magnetoresistance and Magnetization measurement of {Fe(100-x)Vx}75P15C10 Amorphous Ribbons

M. A. S. Karal, M. Kamruzzaman, M. G. M. Hossain, H. M. Iftekhar Jaim, and F A Khan

Abstract

Electrical, Magnetic and Thermal Properties of {Fe(1-x)Mnx}75P15C10

M. Kamruzzaman, H. M. I. Jaim, M. A. S. Karal, and F. A. Khan

Abstract

Magnetization, Magnetoresistance and Hall Resistivity of {Fe(100-x)Vx}75P15C10 Amorphous Ribbons

M. A. S. Karal, M. G. M. Hossain, M. Kamruzzaman, H. M. I. Jaim and F. A. Khan

Abstract

Effect of Mn on the thermal, transport and magnetic properties of Fe0.75P0.15C0.10

M. Kamruzzaman, M. A. S. Karal, H. M. I. Jaim and F. A. Khan

Abstract

Transport, magnetic and thermal properties of (Fe100-xVx)75 P15C10 alloys

M. A. S. Karal, M. Kamruzzaman, M. G. M. Hossain, H. M. I. Jaim, and F. A. Khan

Abstract

Sensitivity of the new four-electrode Focused Impedance Method (FIM) for objects with different conductivity

M. A. S. Karal, K. S. Rabbani

Abstract

Transport and magnetic properties of double exchange (Fe1-xMnx)75P15C10 amorphous ferromagnetic alloys

M. Kamruzzaman, M. A. S. Karal, M. G. M. Hossain, and F. A. Khan

Abstract

Magnetic and electrical properties of Fe76.5-xNbxSi13.5B9Ag1 alloys

M. A. S. Karal, M. Kamruzzaman, M. G. M. Hossain, and F. A. Khan

Abstract

Conductivity dependent sensitivity in 4-electrode Focused Impedance Measurement (FIM) system

M. A. S. Karal, and K. S. Rabbani

Abstract

Structural, dielectric and electrical properties of Zn1-x-yCdxLiyO system

M. Kamruzzaman, M. K. R. Khan, M. M. Rahman, M. A. S. Karal, and M. Shahjahan

Abstract

Transport and magnetic properties of magnetically ordered (Fe100-xVx)75P15C10 amorphous alloys

M. G. M. Hossain, M. A. S. Karal, M. Kamruzzaman, and F. A. Khan

Abstract

A new four-electrode Focused Impedance Measurement (FIM) system for physiological study

K. S. Rabbani and M. A. S. Karal

Abstract

বায়োমেডিকেল ফিজিক্স

Biomedical Physics

Dr. Mohammad Abu Sayem Karal

Abstract

বিশ্ববিদ্যালয় ও কলেজ পর্যায়ের স্নাতক ও স্নাতকোত্তর শ্রেণির ফিজিক্স, মেডিকেল ফিজিক্স, বায়োমেডিকেল ফিজিক্স ও বায়োমেডিকেল ইঞ্জিনিয়ারিং বিভাগের সিলেবাস অনুসারে বইটি লেখা। এতে ষোলোটি অধ্যায়। প্রথম আট অধ্যায়ে বায়োফিজিক্স নিয়ে আলোচনা রয়েছে। শেষ আট অধ্যায়ে আলোচনা করা হয়েছে মেডিকেল ফিজিক্স নিয়ে। বায়োফিজিক্স অংশে ম্যাক্রোমলিকিউলস, নিউক্লিক অ্যাসিড, প্রোটিনের গঠন, এনজাইমের মৌলিক আচরণ, কোষীয় মেমব্রেন, নার্ভাস সিস্টেম, মাসল এবং কার্ডিও-ভাসকুলার সিস্টেম সম্পর্কে বর্ণনা রয়েছে। আর মেডিকেল ফিজিক্স অংশে আলট্রাসাউন্ড ইমেজিং, অন্যান্য ইমেজিং কৌশল, ওডিওলজি, ভাসকুলার পরিমাপ, কার্ডিয়াক পরিমাপ, নিউরোমাসকুলার পরিমাপ, বায়োইলেকট্রিক অ্যামপ্লিফায়ার এবং রেডিয়েশন ও স্বাস্থ্য নিয়ে আলোচনা আছে। প্রয়োজনীয় চিত্র এবং গাণিতিক সমীকরণ বইটির গুরুত্ব বাড়িয়েছে।

Biomedical Physics has been published from a country renowned publishing house ‘Prothoma Prokashan’. This book will be helpful for the students and teachers in all public and private universities and colleges in the undergraduate and graduate level. This is the first book written in Bangla in this field. The book is available in Prothoma Prokashan, Aziz Super Market, Shahbag, Dhaka; and Prothom Alo office at Karwan Bazar, Dhaka, Bangladesh

Laboratory Personel

Biophysics Research Laboratory

The Laboratory focuses heavily on the quality and impact of the researches done in the field of Biophysics as well as in multidisciplinary researches

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Biophysics Research Laboratory mainly deals with artificial lipid membranes synthesis and its characterization. The lipid membranes has been prepared in the form of vesicles. It is also called liposome. Vesicles or liposomes can be categorized into three types depending on their size. It would be giant unilamellar vesicles (GUVs), large unilamellar vesicles (LUVs) and small unilamellar vesicles (SUVs). The size of the GUVs is very similar to real cell and the physiological condition of GUVs is also similar to cell. Therefore, GUVs can be used a artificial cells and the lipid membranes is considered as a mimic of plasma membranes or biomembranes of cells. We also deals with nanoparticles synthesis, characterization and its biological applications

Research Projects

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    Biophysics

    Soft matter Physics

    Biophysics or biological physics is an interdisciplinary science that applies the approaches and methods of physics to study biological systems. Biophysicists study life at every level, from atoms and molecules to cells, organisms, and environments. As innovations come out of physics and biology labs, biophysicists find new areas to explore where they can apply their expertise, create new tools, and learn new things. The work always aims to find out how biological systems work.

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    Biomedical Physics

    Cell, Tissue, MRI, X-ray etc

    The biomedical physics seeks to understand the role of physical processes occurring on molecular, cellular, or macroscopic scales; ranging from the interaction of chemicals with DNA, to the generation of complex electrical signals in the brain and nervous system; and physical principles of medical devices. It also includes the innovations of hardware and software development whether it can be used for future clinical applications or research in animals and humans.

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    Bionanomaterials

    Nanoparticle, Green synthesis etc

    Nanobiomaterials exhibit distinctive characteristics, including mechanical, electrical, and optical properties, which make them suitable for a variety of biological applications. Because of their versatility, they play a central role in nanobiotechnology and make significant contributions to biomedical research and healthcare. Novel approaches for bottom-up and top-down processing of nanostructured biomaterials are highlighted.

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    BioInstrumentations

    FIM, Electroporation, DFL etc

    Bioinstrumentation is the use of bioelectronic instruments for the recording or transmission of physiological information. Biomedical devices are an amalgamation of biology, sensors, interface electronics, microcontrollers, and computer programming, and require the combination of several traditional disciplines including biology, optics, mechanics, mathematics, electronics, chemistry, and computer science. Bioinstrumentation teams gather engineers that design, fabricate, test, and manufacture advanced medical instruments and implantabe devices into a single, more productive unit.

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    Artificial Cell Membrane

    GUV, SUV, MLV etc

    Artificially synthesized lipid membranes of thickness about 4 nm are considered as the mimic of biomembranes of cells. The size (diameter 10 micrometer or more) of the giant unilamellar vesicles (GUVs) of lipid membranes is considered to be the similar size of living cells. Therefore, GUVs can be used for various purposes of biomedical research and applications. Here, we prepared the GUVs of lipid membranes using neutral lipid dioleoylphosphatidylcholine (DOPC) and a mixture of negatively charged lipid dioleoylphosphatidylglycerol (DOPG) and DOPC using natural swelling method. The size of the GUVs was found in the range of 10-85 micrometer

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