Bappaditya Samanta - Academia.edu (original) (raw)

Papers by Bappaditya Samanta

We demonstrate a convenient method for assembling ring-shaped colloidal structures by applying un... more We demonstrate a convenient method for assembling ring-shaped colloidal structures by applying uniform magnetic field to a mixture of 2.7-mum paramagnetic beads, 1-mum non-magnetic polystyrene beads, and a fluid dispersion of 10-nm iron oxide nanoparticles (i.e., ferrofluid). The ferrofluid serves as a magnetic contrast medium and induces dipole moments in both the paramagnetic and non-magnetic beads when an external magnetic field is applied. We discovered that for certain volume fractions of ferrofluid, the attractive forces generated between the smaller non-magnetic beads and the larger magnetic beads induce the non-magnetic particles to form a ring structure around the circumference of the paramagnetic beads. This method differs from similar self-assembly techniques in that the ring structures form solely through magnetic force, rather than depending on random motion and patterned bonding.

Soft Matter, 2009

ABSTRACT

Journal of Sound and Vibration, 2003

Drillstring dynamics is highly non-linear in nature and its model can only be described by a set ... more Drillstring dynamics is highly non-linear in nature and its model can only be described by a set of non-linear differential equations. In addition to this complexity, the drillstring dynamics are not linearly controllable and thus linear control methods are not suitable for suppressing the coupled torsional and lateral vibrations of a rotating drillstring. In this paper a non-linear dynamic inversion

Small, 2009

Skip to Main Content. ...

Physical Review E, 2009

Aggregation in nondiffusion limited colloidal particle suspensions follows a temporal power-law d... more Aggregation in nondiffusion limited colloidal particle suspensions follows a temporal power-law dependence that is consistent with classical diffusion limited cluster aggregation models; however, the dynamic scaling exponents observed in these systems are not adequately described by diffusion limited cluster aggregation models, which expect these scaling exponents to be constant over all experimental conditions. We show here that the dynamic scaling exponents for 10 m particles increase with the particle concentration and the particle-particle free energy of interaction. We provide a semiquantitative explanation for the scaling behavior in terms of the long-ranged particle-particle interaction potential.

Journal of Materials Chemistry, 2008

Thermotherapy is a promising technique for the minimally invasive elimination of solid tumors. He... more Thermotherapy is a promising technique for the minimally invasive elimination of solid tumors. Here we report the fabrication of protein-coated iron oxide NPs (12 nm core) for use as thermal therapeutic agents. These albumin-passivated NPs are stable under physiological conditions, with rapid heating and cell killing capacity upon alternating magnetic field (AMF) exposure. The mode of action is specific: no measurable cytotoxicity was observed for the particle without AMF or for AMF exposure without the particle. † Electronic supplementary information (ESI) available: Histogram, TGA and stability assay data of nanoparticles. See

Angewandte Chemie International Edition, 2011

Journal of the American Chemical Society, 2007

and nonmagnetic (Au) nanoparticles were used to assemble ferritin into nearmonodisperse bionanoco... more and nonmagnetic (Au) nanoparticles were used to assemble ferritin into nearmonodisperse bionanocomposites featuring regular interparticle spacing. The FePt/ferritin assemblies are integrated magnetic materials with ferritin providing added magnetic volume fraction to the magnetic nanocomposite. These assemblies differ from either of their constituent particles in terms of blocking temperature (TB), net magnetic moment, coercivity, and remnance.

We form stable droplets of molten metal, investigate their stability, and demonstrate their poten... more We form stable droplets of molten metal, investigate their stability, and demonstrate their potential for forming electronic devices. Droplets of liquid Ga, 0.1-100 microns in diameter, are suspended in water and stabilized by Au or Fe3O4 nanoparticles. We measure a large reduction of the surface tension of the Ga droplets when nanoparticles assemble at the interface. To investigate electron transport

Nature, 2009

The assembly of complex structures out of simple colloidal building blocks is of practical intere... more The assembly of complex structures out of simple colloidal building blocks is of practical interest for building materials with unique optical properties (for example photonic crystals 1 and DNA biosensors 2 ) and is of fundamental importance in improving our understanding of self-assembly processes occurring on molecular to macroscopic length scales 3-5 . Here we demonstrate a selfassembly principle that is capable of organizing a diverse set of colloidal particles into highly reproducible, rotationally symmetric arrangements. The structures are assembled using the magnetostatic interaction between effectively diamagnetic and paramagnetic particles within a magnetized ferrofluid. The resulting multipolar geometries resemble electrostatic charge configurations such as axial quadrupoles ('Saturn rings'), axial octupoles ('flowers'), linear quadrupoles (poles) and mixed multipole arrangements ('two tone'), which represent just a few examples of the type of structure that can be built using this technique.

Nano Letters, 2009

The creation of ordered cellular structures is important for tissue engineering research. Here, w... more The creation of ordered cellular structures is important for tissue engineering research. Here, we present a novel strategy for the assembly of cells into linear arrangements by negative magnetophoresis using inert, cytocompatible magnetic nanoparticles. In this approach, magnetic nanoparticles dictate the cellular assembly without relying on cell binding or uptake. The linear cell structures are stable and can be further cultured without the magnetic field or nanoparticles, making this an attractive tool for tissue engineering.

Langmuir, 2009

Stimuli-responsive colloidal microcapsules have been fabricated at the oil-water interface using ... more Stimuli-responsive colloidal microcapsules have been fabricated at the oil-water interface using molecular recognition between functionalized gold nanoparticles. Water-soluble beta-cyclodextrin-capped gold nanoparticles and organo-soluble adamantyl-functionalized gold nanoparticles are self-assembled at the water-toluene interface via specific host-guest molecular interactions to provide robust microcapsules. Multivalent interactions of complementary ligands on the nanoparticle surface provide stability to these capsules. Unlike covalently cross-linked microcapsules, the reversible nature of these bridging interactions can be used to manipulate the size of these capsules via introduction of competing adamantane containing amphiphilic guest molecules. Partial disruption of interfacial cross-linking allows microcapsules to coalesce with each other to form larger capsules.

Journal of the American Chemical Society, 2008

Self-assembly of nanoparticles (NPs) provides access to multiscale nanocomposite systems. 1 The o... more Self-assembly of nanoparticles (NPs) provides access to multiscale nanocomposite systems. 1 The optical, electronic, and magnetic properties of such structures are different from their isolated counterparts and have applications in such diverse areas as biosensing, 2 electronic devices, 3 and drug delivery vehicles. 4 Selfassembly at the liquid-liquid interface offers a straightforward pathway for the production of organized nanostructures. 5 In this approach, colloidal particles localize at the interface to minimize the Helmholtz free energy. 6 A range of microporous capsules (colloidosomes) and membranes with controlled pore sizes and pore size distribution have been created using this strategy. 7 Despite the versatility of interfacial assembly strategies, the creation of stable membranes and capsules remains a challenge. 8 The competition between the interfacial energy and spatial fluctuations resulting from NP thermal energy causes instability in asformed membranes and capsules. Two approaches have been recently developed to fabricate stable membranes and colloidosomes using NPs of various sizes. 9 Lin et al., has fabricated a stable ultrathin CdSe membrane at the interface by cross-linking the ligands of CdSe NPs 9a while Duan et al. prepared stable magnetic colloidosomes at the interface of water-in-oil droplets using agrose gelated water phase. 9b In both cases the initially formed membrane and colloidosomes were subjected to thermal treatment (g60°C) to afford stability, and also the cross-linking of the NPs at the interfaces was slow (∼ 8 h). Both, time and temperature of thermal treatment can limit the tunability and applicability of these methods.

Journal of Materials Chemistry, 2007

ABSTRACT Nanocomposite materials consisting of FePt nanoparticles and DNA were constructed via DN... more ABSTRACT Nanocomposite materials consisting of FePt nanoparticles and DNA were constructed via DNA-mediated “bricks and mortar” self-assembly. Electrostatic interaction between the cationic nanoparticles and the DNA through surface recognition led to the formation of extended composite aggregates. These DNA-assembled aggregates feature increased interparticle spacing arising from the DNA “mortar”. The enhanced structure and increased spacing in the bio-nanocomposite assembly was found to alter the magnetic properties of the assemblies, as demonstrated by a 54 K change in blocking temperature (TB).

Chemical Society Reviews, 2008

Gold nanoparticle-polymer composites are versatile and diverse functional materials, with applica... more Gold nanoparticle-polymer composites are versatile and diverse functional materials, with applications in optical, electronic and sensing devices. This tutorial review focuses on the use of polymers to control the assembly of gold nanoparticles. Examples of synthetic polymers and biopolymers are provided, as well as applications of the composite materials in sensing and memory devices.

Chemical Communications, 2009

Dithiocarbamate chemistry is used as a crosslinking tool to fabricate FePt colloidal microcapsule... more Dithiocarbamate chemistry is used as a crosslinking tool to fabricate FePt colloidal microcapsules which provide a versatile scaffold for "host-guest" recognition at the liquid-liquid interface.

Angewandte Chemie International Edition, 2009

Enzymes catalyze chemical reactions with impressive levels of stereospecificity, regioselectivity... more Enzymes catalyze chemical reactions with impressive levels of stereospecificity, regioselectivity, and chemoselectivity. Thus, enzyme immobilization is an important tool for the fabrication of a diverse range of functional materials and devices. To date, a variety of synthetic scaffolds and supports, including gels, [4] macromolecules, nanoreactors, 7] carbon nanotubes, microspheres, and surfaceanchored molecules, have been used for enzyme immobilization. Recently, nanoparticles have been used to immobilize enzymes, and the optical, fluorescent, and magnetic properties of the resulting nanomaterials have been harnessed. Recent examples include the immobilization of lipase and glucose oxidase on gold nanoparticles, and the attachment of a-chymotrypsin to superparamagnetic mag-netite@silica nanoparticles. Retention of activity, however, remains a challenge for many enzyme-immobilized nanoparticle systems. A thin layer of enzyme-nanoparticle conjugates with a high surface-to-volume ratio on a template would provide an ideal geometry for the generation of biocatalysts for industrial applications. In this context, oil-water emulsions provide an ideal template for the construction of such systems. The retention of enzymatic catalysis upon immobilization, coupled with the environmental stability of the resulting conjugate at the oil-water interface is, however, of great importance for the pragmatic application of these systems.

Advanced Materials, 2007

Control over surface hydrophobicity is of crucial importance in tribology, functional coatings, d... more Control over surface hydrophobicity is of crucial importance in tribology, functional coatings, drug delivery, and microfluidic systems. Surfaces with controlled wettabilities have been prepared by numerous chemical modifications using self-assembled monolayers (SAMs), small molecules, polymers [3] and polyelectrolyte multilayers, [4] or by physically changing the surface morphology, [5] or a combination of both. Among the different surfaces, superhydrophobic surfaces with water contact angles (CAs) higher than 150°, have attracted great interest for both fundamental research and practical applications. Superhydrophobic surfaces have generally been obtained by enhancing surface roughness using photolithography and etching followed by deposition of low surface energy materials, e.g. fluorinated compounds. The methods used for roughening surfaces and reducing their surface energy include plasma polymerization, anodic oxidation of aluminum, nanosphere lithography, electrohydrodynamic deposition of polystyrene, plasma fluorination of polybutadiene, aligned polyacrylonitrile nanofibers, perfluorinated polyelectrolytes, composite of polyelectrolyte multilayers and silica nanoparticles (NPs) and layered double hydroxides. Fluorinated materials and SAMs have been used extensively to hydrophobize surfaces, nevertheless the use of nanometer sized fluorinated inorganic NPs has not been explored as means to superhydrophobize surfaces. Surprisingly, the preparation of inorganic NPs stabilized with fluorinated ligands is very rare and was shown on a small number of systems including, gold, palladium, silver, ruthenium and silica, [16] where some of the reports have shown highly ordered arrays of hexagonal packing. To our knowledge there are no reports for the use of these NPs for superhydrophobizing surfaces. Takahara et al have used the sol-gel method to hydrolyze and condense colloidal silica particles on surfaces and then coat them with fluoroalkylsilane. When the fractional amounts of both ingredients were optimized the films exhibited CAs of up to 150°.

Advanced Materials, 2008

COMMUNICATION using the same technique as mentioned above. Finally, the patterned monolayers of N... more COMMUNICATION using the same technique as mentioned above. Finally, the patterned monolayers of NPs were achieved by immersing the substrate into a solution of NPs and CS 2 as mentioned above.

We demonstrate a convenient method for assembling ring-shaped colloidal structures by applying un... more We demonstrate a convenient method for assembling ring-shaped colloidal structures by applying uniform magnetic field to a mixture of 2.7-mum paramagnetic beads, 1-mum non-magnetic polystyrene beads, and a fluid dispersion of 10-nm iron oxide nanoparticles (i.e., ferrofluid). The ferrofluid serves as a magnetic contrast medium and induces dipole moments in both the paramagnetic and non-magnetic beads when an external magnetic field is applied. We discovered that for certain volume fractions of ferrofluid, the attractive forces generated between the smaller non-magnetic beads and the larger magnetic beads induce the non-magnetic particles to form a ring structure around the circumference of the paramagnetic beads. This method differs from similar self-assembly techniques in that the ring structures form solely through magnetic force, rather than depending on random motion and patterned bonding.

Soft Matter, 2009

ABSTRACT

Journal of Sound and Vibration, 2003

Drillstring dynamics is highly non-linear in nature and its model can only be described by a set ... more Drillstring dynamics is highly non-linear in nature and its model can only be described by a set of non-linear differential equations. In addition to this complexity, the drillstring dynamics are not linearly controllable and thus linear control methods are not suitable for suppressing the coupled torsional and lateral vibrations of a rotating drillstring. In this paper a non-linear dynamic inversion

Small, 2009

Skip to Main Content. ...

Physical Review E, 2009

Aggregation in nondiffusion limited colloidal particle suspensions follows a temporal power-law d... more Aggregation in nondiffusion limited colloidal particle suspensions follows a temporal power-law dependence that is consistent with classical diffusion limited cluster aggregation models; however, the dynamic scaling exponents observed in these systems are not adequately described by diffusion limited cluster aggregation models, which expect these scaling exponents to be constant over all experimental conditions. We show here that the dynamic scaling exponents for 10 m particles increase with the particle concentration and the particle-particle free energy of interaction. We provide a semiquantitative explanation for the scaling behavior in terms of the long-ranged particle-particle interaction potential.

Journal of Materials Chemistry, 2008

Thermotherapy is a promising technique for the minimally invasive elimination of solid tumors. He... more Thermotherapy is a promising technique for the minimally invasive elimination of solid tumors. Here we report the fabrication of protein-coated iron oxide NPs (12 nm core) for use as thermal therapeutic agents. These albumin-passivated NPs are stable under physiological conditions, with rapid heating and cell killing capacity upon alternating magnetic field (AMF) exposure. The mode of action is specific: no measurable cytotoxicity was observed for the particle without AMF or for AMF exposure without the particle. † Electronic supplementary information (ESI) available: Histogram, TGA and stability assay data of nanoparticles. See

Angewandte Chemie International Edition, 2011

Journal of the American Chemical Society, 2007

and nonmagnetic (Au) nanoparticles were used to assemble ferritin into nearmonodisperse bionanoco... more and nonmagnetic (Au) nanoparticles were used to assemble ferritin into nearmonodisperse bionanocomposites featuring regular interparticle spacing. The FePt/ferritin assemblies are integrated magnetic materials with ferritin providing added magnetic volume fraction to the magnetic nanocomposite. These assemblies differ from either of their constituent particles in terms of blocking temperature (TB), net magnetic moment, coercivity, and remnance.

We form stable droplets of molten metal, investigate their stability, and demonstrate their poten... more We form stable droplets of molten metal, investigate their stability, and demonstrate their potential for forming electronic devices. Droplets of liquid Ga, 0.1-100 microns in diameter, are suspended in water and stabilized by Au or Fe3O4 nanoparticles. We measure a large reduction of the surface tension of the Ga droplets when nanoparticles assemble at the interface. To investigate electron transport

Nature, 2009

The assembly of complex structures out of simple colloidal building blocks is of practical intere... more The assembly of complex structures out of simple colloidal building blocks is of practical interest for building materials with unique optical properties (for example photonic crystals 1 and DNA biosensors 2 ) and is of fundamental importance in improving our understanding of self-assembly processes occurring on molecular to macroscopic length scales 3-5 . Here we demonstrate a selfassembly principle that is capable of organizing a diverse set of colloidal particles into highly reproducible, rotationally symmetric arrangements. The structures are assembled using the magnetostatic interaction between effectively diamagnetic and paramagnetic particles within a magnetized ferrofluid. The resulting multipolar geometries resemble electrostatic charge configurations such as axial quadrupoles ('Saturn rings'), axial octupoles ('flowers'), linear quadrupoles (poles) and mixed multipole arrangements ('two tone'), which represent just a few examples of the type of structure that can be built using this technique.

Nano Letters, 2009

The creation of ordered cellular structures is important for tissue engineering research. Here, w... more The creation of ordered cellular structures is important for tissue engineering research. Here, we present a novel strategy for the assembly of cells into linear arrangements by negative magnetophoresis using inert, cytocompatible magnetic nanoparticles. In this approach, magnetic nanoparticles dictate the cellular assembly without relying on cell binding or uptake. The linear cell structures are stable and can be further cultured without the magnetic field or nanoparticles, making this an attractive tool for tissue engineering.

Langmuir, 2009

Stimuli-responsive colloidal microcapsules have been fabricated at the oil-water interface using ... more Stimuli-responsive colloidal microcapsules have been fabricated at the oil-water interface using molecular recognition between functionalized gold nanoparticles. Water-soluble beta-cyclodextrin-capped gold nanoparticles and organo-soluble adamantyl-functionalized gold nanoparticles are self-assembled at the water-toluene interface via specific host-guest molecular interactions to provide robust microcapsules. Multivalent interactions of complementary ligands on the nanoparticle surface provide stability to these capsules. Unlike covalently cross-linked microcapsules, the reversible nature of these bridging interactions can be used to manipulate the size of these capsules via introduction of competing adamantane containing amphiphilic guest molecules. Partial disruption of interfacial cross-linking allows microcapsules to coalesce with each other to form larger capsules.

Journal of the American Chemical Society, 2008

Self-assembly of nanoparticles (NPs) provides access to multiscale nanocomposite systems. 1 The o... more Self-assembly of nanoparticles (NPs) provides access to multiscale nanocomposite systems. 1 The optical, electronic, and magnetic properties of such structures are different from their isolated counterparts and have applications in such diverse areas as biosensing, 2 electronic devices, 3 and drug delivery vehicles. 4 Selfassembly at the liquid-liquid interface offers a straightforward pathway for the production of organized nanostructures. 5 In this approach, colloidal particles localize at the interface to minimize the Helmholtz free energy. 6 A range of microporous capsules (colloidosomes) and membranes with controlled pore sizes and pore size distribution have been created using this strategy. 7 Despite the versatility of interfacial assembly strategies, the creation of stable membranes and capsules remains a challenge. 8 The competition between the interfacial energy and spatial fluctuations resulting from NP thermal energy causes instability in asformed membranes and capsules. Two approaches have been recently developed to fabricate stable membranes and colloidosomes using NPs of various sizes. 9 Lin et al., has fabricated a stable ultrathin CdSe membrane at the interface by cross-linking the ligands of CdSe NPs 9a while Duan et al. prepared stable magnetic colloidosomes at the interface of water-in-oil droplets using agrose gelated water phase. 9b In both cases the initially formed membrane and colloidosomes were subjected to thermal treatment (g60°C) to afford stability, and also the cross-linking of the NPs at the interfaces was slow (∼ 8 h). Both, time and temperature of thermal treatment can limit the tunability and applicability of these methods.

Journal of Materials Chemistry, 2007

ABSTRACT Nanocomposite materials consisting of FePt nanoparticles and DNA were constructed via DN... more ABSTRACT Nanocomposite materials consisting of FePt nanoparticles and DNA were constructed via DNA-mediated “bricks and mortar” self-assembly. Electrostatic interaction between the cationic nanoparticles and the DNA through surface recognition led to the formation of extended composite aggregates. These DNA-assembled aggregates feature increased interparticle spacing arising from the DNA “mortar”. The enhanced structure and increased spacing in the bio-nanocomposite assembly was found to alter the magnetic properties of the assemblies, as demonstrated by a 54 K change in blocking temperature (TB).

Chemical Society Reviews, 2008

Gold nanoparticle-polymer composites are versatile and diverse functional materials, with applica... more Gold nanoparticle-polymer composites are versatile and diverse functional materials, with applications in optical, electronic and sensing devices. This tutorial review focuses on the use of polymers to control the assembly of gold nanoparticles. Examples of synthetic polymers and biopolymers are provided, as well as applications of the composite materials in sensing and memory devices.

Chemical Communications, 2009

Dithiocarbamate chemistry is used as a crosslinking tool to fabricate FePt colloidal microcapsule... more Dithiocarbamate chemistry is used as a crosslinking tool to fabricate FePt colloidal microcapsules which provide a versatile scaffold for "host-guest" recognition at the liquid-liquid interface.

Angewandte Chemie International Edition, 2009

Enzymes catalyze chemical reactions with impressive levels of stereospecificity, regioselectivity... more Enzymes catalyze chemical reactions with impressive levels of stereospecificity, regioselectivity, and chemoselectivity. Thus, enzyme immobilization is an important tool for the fabrication of a diverse range of functional materials and devices. To date, a variety of synthetic scaffolds and supports, including gels, [4] macromolecules, nanoreactors, 7] carbon nanotubes, microspheres, and surfaceanchored molecules, have been used for enzyme immobilization. Recently, nanoparticles have been used to immobilize enzymes, and the optical, fluorescent, and magnetic properties of the resulting nanomaterials have been harnessed. Recent examples include the immobilization of lipase and glucose oxidase on gold nanoparticles, and the attachment of a-chymotrypsin to superparamagnetic mag-netite@silica nanoparticles. Retention of activity, however, remains a challenge for many enzyme-immobilized nanoparticle systems. A thin layer of enzyme-nanoparticle conjugates with a high surface-to-volume ratio on a template would provide an ideal geometry for the generation of biocatalysts for industrial applications. In this context, oil-water emulsions provide an ideal template for the construction of such systems. The retention of enzymatic catalysis upon immobilization, coupled with the environmental stability of the resulting conjugate at the oil-water interface is, however, of great importance for the pragmatic application of these systems.

Advanced Materials, 2007

Control over surface hydrophobicity is of crucial importance in tribology, functional coatings, d... more Control over surface hydrophobicity is of crucial importance in tribology, functional coatings, drug delivery, and microfluidic systems. Surfaces with controlled wettabilities have been prepared by numerous chemical modifications using self-assembled monolayers (SAMs), small molecules, polymers [3] and polyelectrolyte multilayers, [4] or by physically changing the surface morphology, [5] or a combination of both. Among the different surfaces, superhydrophobic surfaces with water contact angles (CAs) higher than 150°, have attracted great interest for both fundamental research and practical applications. Superhydrophobic surfaces have generally been obtained by enhancing surface roughness using photolithography and etching followed by deposition of low surface energy materials, e.g. fluorinated compounds. The methods used for roughening surfaces and reducing their surface energy include plasma polymerization, anodic oxidation of aluminum, nanosphere lithography, electrohydrodynamic deposition of polystyrene, plasma fluorination of polybutadiene, aligned polyacrylonitrile nanofibers, perfluorinated polyelectrolytes, composite of polyelectrolyte multilayers and silica nanoparticles (NPs) and layered double hydroxides. Fluorinated materials and SAMs have been used extensively to hydrophobize surfaces, nevertheless the use of nanometer sized fluorinated inorganic NPs has not been explored as means to superhydrophobize surfaces. Surprisingly, the preparation of inorganic NPs stabilized with fluorinated ligands is very rare and was shown on a small number of systems including, gold, palladium, silver, ruthenium and silica, [16] where some of the reports have shown highly ordered arrays of hexagonal packing. To our knowledge there are no reports for the use of these NPs for superhydrophobizing surfaces. Takahara et al have used the sol-gel method to hydrolyze and condense colloidal silica particles on surfaces and then coat them with fluoroalkylsilane. When the fractional amounts of both ingredients were optimized the films exhibited CAs of up to 150°.

Advanced Materials, 2008

COMMUNICATION using the same technique as mentioned above. Finally, the patterned monolayers of N... more COMMUNICATION using the same technique as mentioned above. Finally, the patterned monolayers of NPs were achieved by immersing the substrate into a solution of NPs and CS 2 as mentioned above.