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Pal S, Samanta N, Das Mahanta D, Mitra RK, Chattopadhyay A. Effect of Phospholipid Headgroup Charge on the Structure and Dynamics of Water at the Membrane Interface: A Terahertz Spectroscopic Study. J Phys Chem B 2018. [DOI: 10.1021/acs.jpcb.8b01633] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sreetama Pal
- Academy of Scientific and Innovative Research, India
- CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad 500 007, India
| | - Nirnay Samanta
- S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Debasish Das Mahanta
- S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Rajib Kumar Mitra
- S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
- Academy of Scientific and Innovative Research, India
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Dutta M, Natarajan K, Betal S, Prasankumar RP, Bhalla AS, Guo R. Magnetoelastoelectric coupling in core-shell nanoparticles enabling directional and mode-selective magnetic control of THz beam propagation. NANOSCALE 2017; 9:13052-13059. [PMID: 28836641 DOI: 10.1039/c7nr03504g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Magnetoelastoelectric coupling in an engineered biphasic multiferroic nanocomposite enables a novel magnetic field direction-defined propagation control of terahertz (THz) waves. These core-shell nanoparticles are comprised of a ferromagnetic cobalt ferrite core and a ferroelectric barium titanate shell. An assembly of these nanoparticles, when operated in external magnetic fields, exhibits a controllable amplitude modulation when the magnetic field is applied antiparallel to the THz wave propagation direction; yet the same assembly displays an additional phase modulation when the magnetic field is applied along the propagation direction. While field-induced magnetostriction of the core leads to amplitude modulation, phase modulation is a result of stress-mediated piezoelectricity of the outer ferroelectric shell.
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Affiliation(s)
- Moumita Dutta
- Department of Electrical and Computer Engineering, University of Texas at San Antonio, San Antonio, TX 78249, USA.
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Markl D, Zeitler JA, Rasch C, Michaelsen MH, Müllertz A, Rantanen J, Rades T, Bøtker J. Analysis of 3D Prints by X-ray Computed Microtomography and Terahertz Pulsed Imaging. Pharm Res 2017; 34:1037-1052. [PMID: 28004318 PMCID: PMC5382186 DOI: 10.1007/s11095-016-2083-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 12/07/2016] [Indexed: 11/04/2022]
Abstract
PURPOSE A 3D printer was used to realise compartmental dosage forms containing multiple active pharmaceutical ingredient (API) formulations. This work demonstrates the microstructural characterisation of 3D printed solid dosage forms using X-ray computed microtomography (XμCT) and terahertz pulsed imaging (TPI). METHODS Printing was performed with either polyvinyl alcohol (PVA) or polylactic acid (PLA). The structures were examined by XμCT and TPI. Liquid self-nanoemulsifying drug delivery system (SNEDDS) formulations containing saquinavir and halofantrine were incorporated into the 3D printed compartmentalised structures and in vitro drug release determined. RESULTS A clear difference in terms of pore structure between PVA and PLA prints was observed by extracting the porosity (5.5% for PVA and 0.2% for PLA prints), pore length and pore volume from the XμCT data. The print resolution and accuracy was characterised by XμCT and TPI on the basis of the computer-aided design (CAD) models of the dosage form (compartmentalised PVA structures were 7.5 ± 0.75% larger than designed; n = 3). CONCLUSIONS The 3D printer can reproduce specific structures very accurately, whereas the 3D prints can deviate from the designed model. The microstructural information extracted by XμCT and TPI will assist to gain a better understanding about the performance of 3D printed dosage forms.
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Affiliation(s)
- Daniel Markl
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
| | - J Axel Zeitler
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
| | - Cecilie Rasch
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Maria Høtoft Michaelsen
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Anette Müllertz
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Jukka Rantanen
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Thomas Rades
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Johan Bøtker
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
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Neeraj K, Choudhury S, Polley D, Acharya R, Sinha J, Barman A, Mitra RK. Efficient terahertz anti-reflection properties of metallic anti-dot structures. OPTICS LETTERS 2017; 42:1764-1767. [PMID: 28454155 DOI: 10.1364/ol.42.001764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the use of micrometer-sized copper (Cu) anti-dot structures as a novel terahertz (THz) anti-reflection coating (ARC) material and their superior performance over conventionally used metallic (Cu) thin films. Cu anti-dot structures of two different thicknesses (7 and 10 nm) with varying anti-dot diameters (100, 200, and 300 μm, inter-anti-dot separation fixed at 100 μm) are deposited on silicon substrates by RF magnetron sputtering and e-beam evaporation. The anti-reflection performance of these samples is studied in the frequency range of 0.3-2.2 THz. While continuous metallic (Cu) thin film minimizes the Fabry-Perot (FP) peak, it also suppresses the primary transmission peak, reducing the advantage due to the former effect. On the contrary, the anti-dot arrays reduce both the absolute amplitude of the FP peak and the amplitude ratio (AR) of the FP peak to the primary peak, making them a superior material for ARC applications. The AR can be further manipulated by varying the anti-dot size. A universal conductivity phase-matching condition, which is a prerequisite for the disappearance of the FP peak, is observed in these samples. The enhanced anti-reflection performance promotes these anti-dot structures as an efficient terahertz ARC material.
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Samanta N, Das Mahanta D, Choudhury S, Barman A, Kumar Mitra R. Collective hydration dynamics in some amino acid solutions: A combined GHz-THz spectroscopic study. J Chem Phys 2017; 146:125101. [DOI: 10.1063/1.4978900] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Nirnay Samanta
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Debasish Das Mahanta
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Samiran Choudhury
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Anjan Barman
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Rajib Kumar Mitra
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
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Polley D, Patra A, Barman A, Mitra RK. Terahertz conductivity engineering in surface decorated carbon nanotube films by gold nanoparticles. APPLIED OPTICS 2017; 56:1107-1112. [PMID: 28158120 DOI: 10.1364/ao.56.001107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We report the controllable conductivity of single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes with their surface walls decorated by gold nanoparticles (Au NPs) with varying concentration in terahertz (THz) frequency range. Colloidal Au NPs of nominal diameter ∼15 nm are synthesized by the reduction of gold chloride solution using tri-sodium citrate. A simple chemical route is followed to attach Au NPs on the surfaces of both types of carbon nanotubes (CNTs). The attachment of Au NPs on the sidewalls of CNTs is confirmed by UV-visible spectroscopy and scanning electron microscope images. THz spectroscopic measurements are carried out at room temperature in transmission geometry in the frequency range of 0.3-2.0 THz. It is found that the THz conductivity of the surface decorated SWNT composites can either be increased or decreased by ±15% than that of the as-prepared SWNT composites by carefully choosing the Au NP concentration. The conductivity variation is qualitatively explained in terms of carrier trapping potential for low Au NP density, and alternative carrier conduction pathways at higher Au NP density and analyzed with the help of a modified universal dielectric relaxation model.
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Das Mahanta D, Patra A, Samanta N, Luong TQ, Mukherjee B, Mitra RK. Non-monotonic dynamics of water in its binary mixture with 1,2-dimethoxy ethane: A combined THz spectroscopic and MD simulation study. J Chem Phys 2016; 145:164501. [DOI: 10.1063/1.4964857] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Debasish Das Mahanta
- Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106, India
| | - Animesh Patra
- Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106, India
| | - Nirnay Samanta
- Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106, India
| | - Trung Quan Luong
- Department of Physical Chemistry II, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Biswaroop Mukherjee
- Thematic Unit for Excellence–Computational Materials Science, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106, India
| | - Rajib Kumar Mitra
- Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700106, India
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Preferential solvation of lysozyme in dimethyl sulfoxide/water binary mixture probed by terahertz spectroscopy. Biophys Chem 2016; 216:31-36. [DOI: 10.1016/j.bpc.2016.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 06/14/2016] [Accepted: 06/14/2016] [Indexed: 11/21/2022]
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Samanta N, Luong TQ, Das Mahanta D, Mitra RK, Havenith M. Effect of Short Chain Poly(ethylene glycol)s on the Hydration Structure and Dynamics around Human Serum Albumin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:831-837. [PMID: 26720549 DOI: 10.1021/acs.langmuir.5b03884] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report the changes in the hydration dynamics around a globular protein, human serum albumin (HSA), in the presence of two short chain crowding agents, namely poly(ethylene glycol)s (PEG 200 and 400). The change in the network water structure is investigated using FTIR spectroscopy in the far-infrared (FIR) frequency range. Site specific changes are obtained by time-resolved fluorescence spectroscopic technique using the intrinsic fluorophore tryptophan (Trp214) of HSA. The collective hydration dynamics of HSA in the presence of PEG molecules are obtained using terahertz (THz) time domain spectroscopy (TTDS) and high intensity p-Ge THz measurements. Our study affirms a considerable perturbation of HSA hydration beyond a critical concentration of PEG.
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Affiliation(s)
- Nirnay Samanta
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700098, India
| | - Trung Quan Luong
- Department of Physical Chemistry II, Ruhr-University Bochum , 44780 Bochum, Germany
| | - Debasish Das Mahanta
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700098, India
| | - Rajib Kumar Mitra
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700098, India
| | - Martina Havenith
- Department of Physical Chemistry II, Ruhr-University Bochum , 44780 Bochum, Germany
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Samanta N, Mahanta DD, Mitra RK. Collective hydration dynamics of guanidinium chloride solutions and its possible role in protein denaturation: a terahertz spectroscopic study. Phys Chem Chem Phys 2015; 16:23308-15. [PMID: 25259383 DOI: 10.1039/c4cp03273j] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The remarkable ability of guanidinium chloride (GdmCl) to denature proteins is a well studied yet controversial phenomenon; the exact molecular mechanism is still debatable, especially the role of hydration dynamics, which has been paid less attention. In the present contribution, we have addressed the issue of whether the collective hydrogen bond dynamics of water gets perturbed in the presence of GdmCl and its possible impact on the denaturation of a globular protein human serum albumin (HSA), using terahertz (THz) time domain spectroscopy (TTDS) in the frequency range of 0.3-2.0 THz. The collective hydrogen bond dynamics is determined by fitting the obtained complex dielectric response in a multiple Debye relaxation model. To compare the results, the studies were extended to two more salts: tetramethylguanidinium chloride (TMGdmCl) and sodium chloride (NaCl). It was concluded that the change in hydration dynamics plays a definite role in the protein denaturation process.
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Affiliation(s)
- Nirnay Samanta
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, India.
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Shiraishi K, Muraki K. Metal-film subwavelength-grating polarizer with low insertion losses and high extinction ratios in the terahertz region. OPTICS EXPRESS 2015; 23:16676-16681. [PMID: 26191679 DOI: 10.1364/oe.23.016676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A metal-film subwavelength-grating polarizer with high performance in the terahertz region is presented. The polarizer was obtained by depositing a thin Au film on a resin grating with a triangular cross section duplicated from a metal mold by using the imprinting method. Microstructural parameters were investigated in detail. Measured insertion losses were less than 0.5 dB in the frequency range of 0.5-3 THz, while extinction ratios were 50 dB in the range of 0.5-2.3 THz. The proposed fabrication method is suited to mass production of large-aperture robust polarizers.
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Colleoni MPM, Vidal B. Analysis of the THz response of a simple periodic graphite-based structure. OPTICS EXPRESS 2014; 22:30156-30160. [PMID: 25606945 DOI: 10.1364/oe.22.030156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report the observation of the dichroism effect in simple wire grid structures made of graphite on a paper substrate, i.e. we investigate the feasibility of drawing polarizers for the THz band using conventional graphite-based lead pencils. The displacement of the maximum frequency of the selective absorption phenomenon by varying the wire pitch hints at a polarizing behavior. Measurements of the maximum and minimum of transmission efficiency, extinction ratio and degree of polarization are carried out with a transmission fiber THz-TDS setup. Experimental results show a 9 dB extinction ratio for an inexpensive (<1$) home-made component.
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Samanta N, Das Mahanta D, Kumar Mitra R. Does Urea Alter the Collective Hydrogen-Bond Dynamics in Water? A Dielectric Relaxation Study in the Terahertz-Frequency Region. Chem Asian J 2014; 9:3457-63. [DOI: 10.1002/asia.201402696] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 07/30/2014] [Indexed: 11/09/2022]
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Fragouli D, Das A, Innocenti C, Guttikonda Y, Rahman S, Liu L, Caramia V, Megaridis CM, Athanassiou A. Polymeric films with electric and magnetic anisotropy due to magnetically assembled functional nanofibers. ACS APPLIED MATERIALS & INTERFACES 2014; 6:4535-4541. [PMID: 24625104 DOI: 10.1021/am500335u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate the fabrication of free-standing polymeric nanocomposite films, which present magnetic and electrically conductive anisotropic properties. Magnetically functionalized carbon nanofibers are dispersed in a polymeric solution and, upon casting under a weak external magnetic field, are easily oriented and permanently assembled in a head-to-tail orientation in the polymer film during solvent evaporation. Magnetic and conductive property studies reveal that the resulting films have a high degree of anisotropy in both cases, thus allowing their use in functional complex devices. As a proof of concept, we demonstrate the potential application of these films as flexible THz polarizers. The detailed study shows that very high attenuation values per unit film thickness and fiber mass concentration are achieved, paving thus the way for cost-effective fabrication of substrate-free systems that have advantage over conventional devices realized so far.
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Affiliation(s)
- Despina Fragouli
- Nanophysics, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Genova, Italy
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Polley D, Barman A, Mitra RK. EMI shielding and conductivity of carbon nanotube-polymer composites at terahertz frequency. OPTICS LETTERS 2014; 39:1541-4. [PMID: 24690833 DOI: 10.1364/ol.39.001541] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We investigate the shielding effectiveness and complex conductivity of single-walled carbon nanotubes (SWNT) distributed in a polyvinyl alcohol (PVA) matrix in the THz frequency range. SWNTs are dispersed in PVA matrices with varying SWNT content (keeping the thickness of SWNT/PVA film constant) using a slow-drying method, and terahertz time-domain spectroscopy (THz-TDS) is performed at room temperature in transmission geometry in the frequency range of 0.3-2.1 THz. The transmittance spectra show a possible application of SWNT/PVA composites as low-bandpass filters in the THz frequency region. Shielding effectiveness of all the samples is measured, and, at a particular probing frequency, they tend to follow a linear relationship with SWNT weight fraction in the polymer matrices. THz conductivity of the composite system is described in the light of a.c. hopping conduction.
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