12 research outputs found
Helical Polycarbodiimide Cloaking of Carbon Nanotubes Enables Inter-Nanotube Exciton Energy Transfer Modulation
The
use of single-walled carbon nanotubes (SWCNTs) as near-infrared
optical probes and sensors require the ability to simultaneously modulate
nanotube fluorescence and functionally derivatize the nanotube surface
using noncovalent methods. We synthesized a small library of polycarbodiimides
to noncovalently encapsulate SWCNTs with a diverse set of functional
coatings, enabling their suspension in aqueous solution. These polymers,
known to adopt helical conformations, exhibited ordered surface coverage
on the nanotubes and allowed systematic modulation of nanotube optical
properties, producing up to 12-fold differences in photoluminescence
efficiency. Polymer cloaking of the fluorescent nanotubes facilitated
the first instance of controllable and reversible internanotube exciton
energy transfer, allowing kinetic measurements of dynamic self-assembly
and disassembly
Helical Polycarbodiimide Cloaking of Carbon Nanotubes Enables Inter-Nanotube Exciton Energy Transfer Modulation
The
use of single-walled carbon nanotubes (SWCNTs) as near-infrared
optical probes and sensors require the ability to simultaneously modulate
nanotube fluorescence and functionally derivatize the nanotube surface
using noncovalent methods. We synthesized a small library of polycarbodiimides
to noncovalently encapsulate SWCNTs with a diverse set of functional
coatings, enabling their suspension in aqueous solution. These polymers,
known to adopt helical conformations, exhibited ordered surface coverage
on the nanotubes and allowed systematic modulation of nanotube optical
properties, producing up to 12-fold differences in photoluminescence
efficiency. Polymer cloaking of the fluorescent nanotubes facilitated
the first instance of controllable and reversible internanotube exciton
energy transfer, allowing kinetic measurements of dynamic self-assembly
and disassembly
Cell Membrane Proteins Modulate the Carbon Nanotube Optical Bandgap <i>via</i> Surface Charge Accumulation
Cell adhesion is a protein-mediated
process intrinsic to most living
organisms. Dysfunction in cell adhesion processes is implicated in
various diseases, including thrombosis and metastatic cancers. Using
an approach to resolve spectral features from cell membrane-associated
photoluminescent single-walled carbon nanotubes, we found that nanotube
optical bandgaps respond to the electrostatic potential of the cell
surface, which corresponds to cell adhesion properties. We studied
the carbon nanotube emission energy response to solution ionic potentials,
which suggests sensitivity to local charge accumulation. We conclude
that nanotubes respond to cell surface electrostatic potentials that
are mediated by membrane proteins, which vary significantly across
cell types. These findings portend the optical measurement of surface
electrostatic potentials for biophysical measurements and biomedical
applications
A Carbon Nanotube Optical Sensor Reports Nuclear Entry <i>via</i> a Noncanonical Pathway
Single-walled
carbon nanotubes are of interest in biomedicine for
imaging and molecular sensing applications and as shuttles for various
cargos such as chemotherapeutic drugs, peptides, proteins, and oligonucleotides.
Carbon nanotube surface chemistry can be modulated for subcellular
targeting while preserving photoluminescence for label-free visualization
in complex biological environments, making them attractive materials
for such studies. The cell nucleus is a potential target for many
pathologies including cancer and infectious diseases. Understanding
mechanisms of nanomaterial delivery to the nucleus may facilitate
diagnostics, drug development, and gene-editing tools. Currently,
there are no systematic studies to understand how these nanomaterials
gain access to the nucleus. Herein, we developed a carbon nanotube
based hybrid material that elucidate a distinct mechanism of nuclear
translocation of a nanomaterial in cultured cells. We developed a
nuclear-targeted probe <i>via</i> cloaking photoluminescent
single-walled carbon nanotubes in a guanidinium-functionalized helical
polycarbodiimide. We found that the nuclear entry of the nanotubes
was mediated by the import receptor importin β without the aid
of importin α and not by the more common importin α/β
pathway. Additionally, the nanotube photoluminescence exhibited distinct
red-shifting upon entry to the nucleus, potentially functioning as
a reporter of the importin β-mediated nuclear transport process.
This work delineates a noncanonical mechanism for nanomaterial delivery
to the nucleus and provides a reporter for the study of nucleus-related
pathologies
A Carbon Nanotube Optical Sensor Reports Nuclear Entry <i>via</i> a Noncanonical Pathway
Single-walled
carbon nanotubes are of interest in biomedicine for
imaging and molecular sensing applications and as shuttles for various
cargos such as chemotherapeutic drugs, peptides, proteins, and oligonucleotides.
Carbon nanotube surface chemistry can be modulated for subcellular
targeting while preserving photoluminescence for label-free visualization
in complex biological environments, making them attractive materials
for such studies. The cell nucleus is a potential target for many
pathologies including cancer and infectious diseases. Understanding
mechanisms of nanomaterial delivery to the nucleus may facilitate
diagnostics, drug development, and gene-editing tools. Currently,
there are no systematic studies to understand how these nanomaterials
gain access to the nucleus. Herein, we developed a carbon nanotube
based hybrid material that elucidate a distinct mechanism of nuclear
translocation of a nanomaterial in cultured cells. We developed a
nuclear-targeted probe <i>via</i> cloaking photoluminescent
single-walled carbon nanotubes in a guanidinium-functionalized helical
polycarbodiimide. We found that the nuclear entry of the nanotubes
was mediated by the import receptor importin β without the aid
of importin α and not by the more common importin α/β
pathway. Additionally, the nanotube photoluminescence exhibited distinct
red-shifting upon entry to the nucleus, potentially functioning as
a reporter of the importin β-mediated nuclear transport process.
This work delineates a noncanonical mechanism for nanomaterial delivery
to the nucleus and provides a reporter for the study of nucleus-related
pathologies
A Carbon Nanotube Optical Sensor Reports Nuclear Entry <i>via</i> a Noncanonical Pathway
Single-walled
carbon nanotubes are of interest in biomedicine for
imaging and molecular sensing applications and as shuttles for various
cargos such as chemotherapeutic drugs, peptides, proteins, and oligonucleotides.
Carbon nanotube surface chemistry can be modulated for subcellular
targeting while preserving photoluminescence for label-free visualization
in complex biological environments, making them attractive materials
for such studies. The cell nucleus is a potential target for many
pathologies including cancer and infectious diseases. Understanding
mechanisms of nanomaterial delivery to the nucleus may facilitate
diagnostics, drug development, and gene-editing tools. Currently,
there are no systematic studies to understand how these nanomaterials
gain access to the nucleus. Herein, we developed a carbon nanotube
based hybrid material that elucidate a distinct mechanism of nuclear
translocation of a nanomaterial in cultured cells. We developed a
nuclear-targeted probe <i>via</i> cloaking photoluminescent
single-walled carbon nanotubes in a guanidinium-functionalized helical
polycarbodiimide. We found that the nuclear entry of the nanotubes
was mediated by the import receptor importin β without the aid
of importin α and not by the more common importin α/β
pathway. Additionally, the nanotube photoluminescence exhibited distinct
red-shifting upon entry to the nucleus, potentially functioning as
a reporter of the importin β-mediated nuclear transport process.
This work delineates a noncanonical mechanism for nanomaterial delivery
to the nucleus and provides a reporter for the study of nucleus-related
pathologies
A Carbon Nanotube Optical Sensor Reports Nuclear Entry <i>via</i> a Noncanonical Pathway
Single-walled
carbon nanotubes are of interest in biomedicine for
imaging and molecular sensing applications and as shuttles for various
cargos such as chemotherapeutic drugs, peptides, proteins, and oligonucleotides.
Carbon nanotube surface chemistry can be modulated for subcellular
targeting while preserving photoluminescence for label-free visualization
in complex biological environments, making them attractive materials
for such studies. The cell nucleus is a potential target for many
pathologies including cancer and infectious diseases. Understanding
mechanisms of nanomaterial delivery to the nucleus may facilitate
diagnostics, drug development, and gene-editing tools. Currently,
there are no systematic studies to understand how these nanomaterials
gain access to the nucleus. Herein, we developed a carbon nanotube
based hybrid material that elucidate a distinct mechanism of nuclear
translocation of a nanomaterial in cultured cells. We developed a
nuclear-targeted probe <i>via</i> cloaking photoluminescent
single-walled carbon nanotubes in a guanidinium-functionalized helical
polycarbodiimide. We found that the nuclear entry of the nanotubes
was mediated by the import receptor importin β without the aid
of importin α and not by the more common importin α/β
pathway. Additionally, the nanotube photoluminescence exhibited distinct
red-shifting upon entry to the nucleus, potentially functioning as
a reporter of the importin β-mediated nuclear transport process.
This work delineates a noncanonical mechanism for nanomaterial delivery
to the nucleus and provides a reporter for the study of nucleus-related
pathologies
Control of Carbon Nanotube Solvatochromic Response to Chemotherapeutic Agents
Alkylating
agents such as cisplatin play an essential role in chemotherapy regimens,
but initial and acquired resistance in many cancer types often dampen
therapeutic response. The poor understanding of the mechanisms of
resistance highlight the need for quantitative measurements of alkylating
agent distribution at both the tissue and subcellular levels. Sensors
for use in live animals and cells would allow for more effective study
of drug action and resistance. Toward this end, single-walled carbon
nanotubes suspended with single-stranded DNA have suitable optical
properties for in vivo sensors, such as near-infrared emission and
sensitivity to the local environment via solvatochromic responses.
Currently, solvatochromic changes of such sensors have been limited
by the chemical nature of the analyte, making it impossible to control
the direction of energy emission changes. Here, we describe a new
approach to control the direction and magnitude of solvatochromic
responses of carbon nanotubes. We found that the alkylation of DNA
on the nanotube surface can result in small changes in DNA conformation
that allow the adsorption of amphiphiles to produce large differences
(>14 nm) in response to different drugs. The technique surprisingly
revealed differences among drugs upon alkylation. The ability to control
carbon nanotube solvatochromism as desired may potentially expand
the application of nanotube-based optical sensors for new classes
of analytes
Electrostatic Screening Modulates Analyte Binding and Emission of Carbon Nanotubes
Many
nanomaterials are promising biosensor elements due to capabilities
for transduction of biomolecular interactions into an electrical or
optical signal. Certain nanomaterials have intrinsic charges and are
thus susceptible to electrostatic forces that may enhance or attenuate
their response. Here, using a combination of experimental and computational
approaches, we found and characterized a critical role of the solvent
salt conditions in determining the extent of optical changes due to
anionic analyte interaction with an intrinsically responsive nanomaterial,
single-walled carbon nanotubes. Using a well-characterized model anionic
analyte, we found that monovalent salts enabled greater optical changes
of a polyanion-bound carbon nanotube in a highly dose-dependent manner
but not with a neutrally charged analyte. Molecular dynamics simulations
were used to derive a quantitative understanding of this mechanism
from a free-energy perspective. We also show that salt can be used
to enhance the sensitivity of detection for a polyanionic analyte.
These results suggest that electrostatic screening is an important
parameter for intrinsically charged nanoparticle sensors and it may
be tuned to control the response to analytes
Measuring Uptake Dynamics of Multiple Identifiable Carbon Nanotube Species via High-Speed Confocal Raman Imaging of Live Cells
Carbon nanotube uptake was measured via high-speed confocal
Raman imaging in live cells. Spatial and temporal tracking of two
cell-intrinsic and nine nanotube-derived Raman bands was conducted
simultaneously in RAW 264.7 macrophages. Movies resolved single (<i>n</i>, <i>m</i>) species, defects, and aggregation
states of nanotubes transiently as well as the cell position, denoted
by lipid and protein signals. This work portends the real-time molecular
imaging of live cells and tissues using Raman spectroscopy, affording
multiplexing and complete photostability