Dr. Amitava Das - Academia.edu (original) (raw)
Papers by Dr. Amitava Das
Journal of Materials Chemistry B, 2016
Two-photon imaging of endogenous bisulphite ions of the hippocampus region of mouse brain.
Inorganic chemistry, Jan 21, 2016
A new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based probe molecule (L) is synthesized... more A new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based probe molecule (L) is synthesized for specific binding to Hg(2+) ion in physiological condition with an associated luminescence ON response in the near-IR region of the spectrum. Appropriate functionalization in the 5-position of each of two pyrrole moieties with styryl functionality in a BODIPY core helped us in achieving the extended conjugation and a facile intramolecular charge transfer transition with a narrow energy gap for frontier orbitals. This accounted for a poor emission quantum yield for the probe molecule L. Binding to Hg(2+) helped in interrupting the facile intramolecular charge transfer (ICT) process that was initially operational for L. This resulted in a hypsochromic shift of absorption band and a turn-on luminescence response with λMax(Ems) of 650 nm on specific binding to Hg(2+). Observed spectral changes are rationalized based on quantum chemical calculations. Interestingly, this reagent is found t...
Chemical communications (Cambridge, England), Jan 28, 2018
A new physiologically benign and cell membrane permeable BODIPY based molecular probe, MB-Sn, spe... more A new physiologically benign and cell membrane permeable BODIPY based molecular probe, MB-Sn, specifically senses intracellular hydrogen polysulfides (H2Sn, n > 1) localized in the endoplasmic reticulum. This reagent is suitable for mapping the intracellular distribution of H2Sn by wide-field as well as super-resolution Structured Illumination Microscopy (SIM).
Analytical chemistry, Dec 20, 2016
Reagents that allows detection and monitoring of crucial biomarkers with luminescence ON response... more Reagents that allows detection and monitoring of crucial biomarkers with luminescence ON response have significance in clinical diagnostics. A new coumarin derivative is reported here, which could be used for specific and efficient chemodosimetric detection of cysteine, an important biomarker. The probe is successfully used for studying the biochemical transformation of N-acetylcysteine, a commonly prescribed Cys supplement drug to Cys by aminoacylase-1 (ACY-1), an important and endogenous mammalian enzyme. The possibility of using this reagent for quantification of ACY-1 in blood serum samples is also explored. Nontoxic nature and cell membrane permeability are key features of this probe and are ideally suited for imaging intracellular Cys in normal and cancerous cell lines. Our studies have also revealed that this reagent could be utilized as a redox switch to monitor the hydrogen-peroxide-induced oxidative stress in living SW480 cell lines. Peroxide-mediated cysteine oxidation ha...
Chemical Communications, 2015
Use of a cysteine specific chemodosimetric receptor for probing its release in the ER-region of t... more Use of a cysteine specific chemodosimetric receptor for probing its release in the ER-region of the HepG2 cells during drug metabolism and silica based strips for quantitative estimation of Cys in a human blood plasma sample.
Scientific Reports, 2019
Creation of hollow, one-dimensional nanomaterials has gained great recent attention in the chemic... more Creation of hollow, one-dimensional nanomaterials has gained great recent attention in the chemical and material sciences. In a study aimed at discovering new functional materials of this type, we observed that an amphiphilic diacetylene (DA) derivative, containing an azobenzene moiety and an oligo-ethylene group, self-assembles to form nanotubes and undergoes photopolymerization to form hollow polydiacetylene (PDA) nanotubes with a uniform wall thickness and diameter. The azobenzene-PDA nanotubes are photoresponsive in that on-and-off UV-irradiation leads to a reversible morphological change between straight and bent forms in association with E-Z photoisomerization of the azobenzene group. Owing to the UV-induced structural change feature, the new DA and PDA nanotubes serve as a controlled release material. Accordingly, fluorescent rhodamine B encapsulated inside the nanotubes are effectively released by using repeated on-off UV irradiation. Furthermore, photo-release of rhodamine ...
Bioconjugate Chemistry, 2018
Sumit Kumar Pramanik and Sreejesh Sreedharan has equal contribution. Cell studies for Nanocapsule... more Sumit Kumar Pramanik and Sreejesh Sreedharan has equal contribution. Cell studies for Nanocapsules Cellular Uptake experiments of the nanocapsules (Single colour SIM/ Wide Field/
Nanoscale, Jan 18, 2018
Self-assembly of suitable molecular building blocks is an efficient and convenient approach to ge... more Self-assembly of suitable molecular building blocks is an efficient and convenient approach to generate nanomaterials with various morphologies and functions. Moreover, understanding the nature of molecules and controlling factors of their self-assembly process is crucial in fundamental aspects of molecular self-assembly which provide insights into the design of new assemblies with functional nano-architectures. To this end, the present study reports water induced self-assembled multifaceted morphology formation and the plausible pathway of the morphology transformation of a single poly(aryl ether) dendron amphiphile 1(D). In THF, 1(D) self-assembles into helical fibers. However, with an increase in the water fraction in its THF solution, the morphology changes to nanorods through an intermediate scroll-up pathway of exfoliated fibers. The nanorod formation and transformation of 1(D) are investigated using various microscopy and spectroscopy techniques, which indicate that it has hi...
Chemical communications (Cambridge, England), Jan 23, 2017
β-NaYF4:Yb,Gd up-conversion nanoparticles, UCNPs, surface functionalized with suitable targetting... more β-NaYF4:Yb,Gd up-conversion nanoparticles, UCNPs, surface functionalized with suitable targetting peptides function as nontoxic lysosome-specific imaging probes.
Analytical chemistry, Jan 26, 2017
Selective detection of nitroxyl (HNO), which has recently been identified as a reactive nitrogen ... more Selective detection of nitroxyl (HNO), which has recently been identified as a reactive nitrogen species, is a challenging task. We report a BODIPY-based luminescence ON reagent for detection of HNO in aqueous solution and in live RAW 264.7 cells, based on the soft nucleophilicity of the phosphine oxide functionality towards HNO. The probe shows high selectivity to HNO over other reactive oxygen/nitrogen and sulphur species. Luminescence properties of the BODIPY based chemodosimetric reagent make it an ideal candidate for use as a reagent for super resolution structured illumination microscopy. The viability of the reagent for biological in-vivo imaging application was also confirmed using Artemia as a model.
Journal of the American Chemical Society, 2016
The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry b... more The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry breaking or kinetically controlled random assembly formation. Here an attempt has been made to address this issue through chiral anion exchange. A new class of cationic achiral C3-symmetric gelator devoid of any conventional gelation assisting functional units is found to form both right- and left-handed helical structures. A chiral counteranion exchange-assisted approach is successfully introduced to control the chirality sign and thereby to obtain preferred homochiral assemblies. Formation of anion-assisted chiral assembly was confirmed by circular dichroism (CD) spectroscopy, microscopic images, and crystal structure. The X-ray crystal structure reveals the construction of helical assemblies with opposite handedness for (+)- and (-)-chiral anion reformed gelators. The appropriate counteranion driven ion-pair-assisted hydrogen-bonding interactions are found responsible for the helical bias control in this C3-symmetric gelator.
Bioconjugate chemistry, Sep 9, 2016
Fluoroquinolones are 3rdgeneration broad spectrum bactericidal antibiotics and work against both ... more Fluoroquinolones are 3rdgeneration broad spectrum bactericidal antibiotics and work against both gram positive and gram negative bacteria. Levofloxacin (L), a fluoroquinolone, is widely used in anti-infective chemotherapy, urinary tract infection and treating pneumonia. The main pathogen for urinary tract infections is Escherichia coli and Streptococcus pneumoniae is responsible for the pneumonia, predominantly a lower respiratory tract infection. Poor permeability of L leads to the use of higher dose of this drug and excess drug exists in the outer cellular fluid leads to central nervous system (CNS) abnormality. One way to counter this is to improve the lipophilicity of the drug molecule and accordingly, we have synthesized two new Levofloxacin derivatives, which participated in the spatiotemporal release of drug via disulfide bond cleavage induced by glutathione (GSH). Recent studies with Streptococcus mutants suggest that it is localized in epithelial lining fluid (ELF) of the n...
Journal of Materials Chemistry B, 2013
The size distribution of the octadecyl rhodamine-6G (5.0 x 10-5 M) in waterethanol (4:1, v/v) media.
Journal of Nanomaterials, 2007
Controlled aggregation of tetrakis-(4-(hexadecyl oxy)-phenyl) porphyrin and its copper(II)-comple... more Controlled aggregation of tetrakis-(4-(hexadecyl oxy)-phenyl) porphyrin and its copper(II)-complex was studied in mix-solvent system at room temperature. Structure of the aggregates was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and UV-visible spectroscopy. TEM results indicated the formation of organized nanostructures from the porphyrin derivative and its corresponding copper(II)-complex. XRD results showed that the bulk and nanostructured free porphyrin derivatives had the similar crystalline morphology. UV-visible-NIR spectroscopic data showed broad red-shifted Soret band, indicating JJ aggregation among the monomer units. Conjugate effect of lateralπ-πinteraction among the tetrapyrrole cores and hydrophobic interaction among the long alkane chains substituted in the peripheral phenyl rings is believed to lead to the organized nanostructures. Effect of solvent ratio on the aggregate structure is al...
Organic Letters, 2007
[structure/diagram: see text] Spectral responses at two different wavelengths revealed that BP(OH... more [structure/diagram: see text] Spectral responses at two different wavelengths revealed that BP(OH)2 ([2,2'-bipyridyl]-3,3'-diol) can function as a combinatorial logic circuit for a molecular half-subtractor with acid and base as input variables.
Organic & Biomolecular Chemistry, 2013
![Research paper thumbnail of Studies on [3]pseudorotaxane formation from a bis-azacrown derivative as host and imidazolium ion-derivatives as guest](https://attachments.academia-assets.com/108928738/thumbnails/1.jpg)
](Organic & Biomolecular Chemistry, 2011
Chemical Communications, 2010
Journal of Materials Chemistry B, 2016
Two-photon imaging of endogenous bisulphite ions of the hippocampus region of mouse brain.
Inorganic chemistry, Jan 21, 2016
A new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based probe molecule (L) is synthesized... more A new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based probe molecule (L) is synthesized for specific binding to Hg(2+) ion in physiological condition with an associated luminescence ON response in the near-IR region of the spectrum. Appropriate functionalization in the 5-position of each of two pyrrole moieties with styryl functionality in a BODIPY core helped us in achieving the extended conjugation and a facile intramolecular charge transfer transition with a narrow energy gap for frontier orbitals. This accounted for a poor emission quantum yield for the probe molecule L. Binding to Hg(2+) helped in interrupting the facile intramolecular charge transfer (ICT) process that was initially operational for L. This resulted in a hypsochromic shift of absorption band and a turn-on luminescence response with λMax(Ems) of 650 nm on specific binding to Hg(2+). Observed spectral changes are rationalized based on quantum chemical calculations. Interestingly, this reagent is found t...
Chemical communications (Cambridge, England), Jan 28, 2018
A new physiologically benign and cell membrane permeable BODIPY based molecular probe, MB-Sn, spe... more A new physiologically benign and cell membrane permeable BODIPY based molecular probe, MB-Sn, specifically senses intracellular hydrogen polysulfides (H2Sn, n > 1) localized in the endoplasmic reticulum. This reagent is suitable for mapping the intracellular distribution of H2Sn by wide-field as well as super-resolution Structured Illumination Microscopy (SIM).
Analytical chemistry, Dec 20, 2016
Reagents that allows detection and monitoring of crucial biomarkers with luminescence ON response... more Reagents that allows detection and monitoring of crucial biomarkers with luminescence ON response have significance in clinical diagnostics. A new coumarin derivative is reported here, which could be used for specific and efficient chemodosimetric detection of cysteine, an important biomarker. The probe is successfully used for studying the biochemical transformation of N-acetylcysteine, a commonly prescribed Cys supplement drug to Cys by aminoacylase-1 (ACY-1), an important and endogenous mammalian enzyme. The possibility of using this reagent for quantification of ACY-1 in blood serum samples is also explored. Nontoxic nature and cell membrane permeability are key features of this probe and are ideally suited for imaging intracellular Cys in normal and cancerous cell lines. Our studies have also revealed that this reagent could be utilized as a redox switch to monitor the hydrogen-peroxide-induced oxidative stress in living SW480 cell lines. Peroxide-mediated cysteine oxidation ha...
Chemical Communications, 2015
Use of a cysteine specific chemodosimetric receptor for probing its release in the ER-region of t... more Use of a cysteine specific chemodosimetric receptor for probing its release in the ER-region of the HepG2 cells during drug metabolism and silica based strips for quantitative estimation of Cys in a human blood plasma sample.
Scientific Reports, 2019
Creation of hollow, one-dimensional nanomaterials has gained great recent attention in the chemic... more Creation of hollow, one-dimensional nanomaterials has gained great recent attention in the chemical and material sciences. In a study aimed at discovering new functional materials of this type, we observed that an amphiphilic diacetylene (DA) derivative, containing an azobenzene moiety and an oligo-ethylene group, self-assembles to form nanotubes and undergoes photopolymerization to form hollow polydiacetylene (PDA) nanotubes with a uniform wall thickness and diameter. The azobenzene-PDA nanotubes are photoresponsive in that on-and-off UV-irradiation leads to a reversible morphological change between straight and bent forms in association with E-Z photoisomerization of the azobenzene group. Owing to the UV-induced structural change feature, the new DA and PDA nanotubes serve as a controlled release material. Accordingly, fluorescent rhodamine B encapsulated inside the nanotubes are effectively released by using repeated on-off UV irradiation. Furthermore, photo-release of rhodamine ...
Bioconjugate Chemistry, 2018
Sumit Kumar Pramanik and Sreejesh Sreedharan has equal contribution. Cell studies for Nanocapsule... more Sumit Kumar Pramanik and Sreejesh Sreedharan has equal contribution. Cell studies for Nanocapsules Cellular Uptake experiments of the nanocapsules (Single colour SIM/ Wide Field/
Nanoscale, Jan 18, 2018
Self-assembly of suitable molecular building blocks is an efficient and convenient approach to ge... more Self-assembly of suitable molecular building blocks is an efficient and convenient approach to generate nanomaterials with various morphologies and functions. Moreover, understanding the nature of molecules and controlling factors of their self-assembly process is crucial in fundamental aspects of molecular self-assembly which provide insights into the design of new assemblies with functional nano-architectures. To this end, the present study reports water induced self-assembled multifaceted morphology formation and the plausible pathway of the morphology transformation of a single poly(aryl ether) dendron amphiphile 1(D). In THF, 1(D) self-assembles into helical fibers. However, with an increase in the water fraction in its THF solution, the morphology changes to nanorods through an intermediate scroll-up pathway of exfoliated fibers. The nanorod formation and transformation of 1(D) are investigated using various microscopy and spectroscopy techniques, which indicate that it has hi...
Chemical communications (Cambridge, England), Jan 23, 2017
β-NaYF4:Yb,Gd up-conversion nanoparticles, UCNPs, surface functionalized with suitable targetting... more β-NaYF4:Yb,Gd up-conversion nanoparticles, UCNPs, surface functionalized with suitable targetting peptides function as nontoxic lysosome-specific imaging probes.
Analytical chemistry, Jan 26, 2017
Selective detection of nitroxyl (HNO), which has recently been identified as a reactive nitrogen ... more Selective detection of nitroxyl (HNO), which has recently been identified as a reactive nitrogen species, is a challenging task. We report a BODIPY-based luminescence ON reagent for detection of HNO in aqueous solution and in live RAW 264.7 cells, based on the soft nucleophilicity of the phosphine oxide functionality towards HNO. The probe shows high selectivity to HNO over other reactive oxygen/nitrogen and sulphur species. Luminescence properties of the BODIPY based chemodosimetric reagent make it an ideal candidate for use as a reagent for super resolution structured illumination microscopy. The viability of the reagent for biological in-vivo imaging application was also confirmed using Artemia as a model.
Journal of the American Chemical Society, 2016
The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry b... more The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry breaking or kinetically controlled random assembly formation. Here an attempt has been made to address this issue through chiral anion exchange. A new class of cationic achiral C3-symmetric gelator devoid of any conventional gelation assisting functional units is found to form both right- and left-handed helical structures. A chiral counteranion exchange-assisted approach is successfully introduced to control the chirality sign and thereby to obtain preferred homochiral assemblies. Formation of anion-assisted chiral assembly was confirmed by circular dichroism (CD) spectroscopy, microscopic images, and crystal structure. The X-ray crystal structure reveals the construction of helical assemblies with opposite handedness for (+)- and (-)-chiral anion reformed gelators. The appropriate counteranion driven ion-pair-assisted hydrogen-bonding interactions are found responsible for the helical bias control in this C3-symmetric gelator.
Bioconjugate chemistry, Sep 9, 2016
Fluoroquinolones are 3rdgeneration broad spectrum bactericidal antibiotics and work against both ... more Fluoroquinolones are 3rdgeneration broad spectrum bactericidal antibiotics and work against both gram positive and gram negative bacteria. Levofloxacin (L), a fluoroquinolone, is widely used in anti-infective chemotherapy, urinary tract infection and treating pneumonia. The main pathogen for urinary tract infections is Escherichia coli and Streptococcus pneumoniae is responsible for the pneumonia, predominantly a lower respiratory tract infection. Poor permeability of L leads to the use of higher dose of this drug and excess drug exists in the outer cellular fluid leads to central nervous system (CNS) abnormality. One way to counter this is to improve the lipophilicity of the drug molecule and accordingly, we have synthesized two new Levofloxacin derivatives, which participated in the spatiotemporal release of drug via disulfide bond cleavage induced by glutathione (GSH). Recent studies with Streptococcus mutants suggest that it is localized in epithelial lining fluid (ELF) of the n...
Journal of Materials Chemistry B, 2013
The size distribution of the octadecyl rhodamine-6G (5.0 x 10-5 M) in waterethanol (4:1, v/v) media.
Journal of Nanomaterials, 2007
Controlled aggregation of tetrakis-(4-(hexadecyl oxy)-phenyl) porphyrin and its copper(II)-comple... more Controlled aggregation of tetrakis-(4-(hexadecyl oxy)-phenyl) porphyrin and its copper(II)-complex was studied in mix-solvent system at room temperature. Structure of the aggregates was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and UV-visible spectroscopy. TEM results indicated the formation of organized nanostructures from the porphyrin derivative and its corresponding copper(II)-complex. XRD results showed that the bulk and nanostructured free porphyrin derivatives had the similar crystalline morphology. UV-visible-NIR spectroscopic data showed broad red-shifted Soret band, indicating JJ aggregation among the monomer units. Conjugate effect of lateralπ-πinteraction among the tetrapyrrole cores and hydrophobic interaction among the long alkane chains substituted in the peripheral phenyl rings is believed to lead to the organized nanostructures. Effect of solvent ratio on the aggregate structure is al...
Organic Letters, 2007
[structure/diagram: see text] Spectral responses at two different wavelengths revealed that BP(OH... more [structure/diagram: see text] Spectral responses at two different wavelengths revealed that BP(OH)2 ([2,2'-bipyridyl]-3,3'-diol) can function as a combinatorial logic circuit for a molecular half-subtractor with acid and base as input variables.
Organic & Biomolecular Chemistry, 2013
Organic & Biomolecular Chemistry, 2011
Chemical Communications, 2010