14 research outputs found
Cooperative Macromolecular Self-Assembly toward Polymeric Assemblies with Multiple and Bioactive Functions
ConspectusIn the past
decades, polymer based nanoscale polymeric assemblies
have attracted continuous interest due to their potential applications
in many fields, such as nanomedicine. Many efforts have been dedicated
to tailoring the three-dimensional architecture and the placement
of functional groups at well-defined positions within the polymeric
assemblies, aiming to augment their function. To achieve such goals,
in one way, novel polymeric building blocks can be designed by controlled
living polymerization methodology and advanced chemical modifications.
In contrast, by focusing on the end function, others and we have been
practicing strategies of cooperative self-assembly of multiple polymeric
building blocks chosen from the vast library of conventional block
polymers which are easily available. The advantages of such strategies
lie in the simplicity of the preparation process and versatile choice
of the constituent polymers in terms of their chemical structure and
functionality as well as the fact that cooperative self-assembly based
on supramolecular interactions offers elegant and energy-efficient
bottom-up strategies. Combination of these principles has been exploited
to optimize the architecture of polymeric assemblies with improved
function, to impart new functionality into micelles and to realize
polymeric nanocomplexes exhibiting functional integration, similar
to some natural systems like artificial viruses, molecular chaperones,
multiple enzyme systems, and so forth.In this Account, we shall
first summarize several straightforward
designing principles with which cooperative assembly of multiple polymeric
building blocks can be implemented, aiming to construct polymeric
nanoassemblies with hierarchal structure and enhanced functionalities.
Next, examples will be discussed to demonstrate the possibility to
create multifunctional nanoparticles by combination of the designing
principles and judiciously choosing of the building blocks. We focus
on multifunctional nanoparticles which can partially address challenges
widely existing in nanomedicine such as long blood circulation, efficient
cellular uptake, and controllable release of payloads. Finally, bioactive
polymeric assemblies, which have certain functions closely mimicking
those of some natural systems, will be used to conceive the concept
of functional integration
Stabilization of Multimeric Enzymes against Heat Inactivation by Chitosan-<i>graft</i>-poly(<i>N</i>‑isopropylacrylamide) in Confined Spaces
The inactivation
of multimeric enzymes is a more complicated process
compared with that of monomeric enzymes. Stabilization of multimeric
enzymes is regarded as a challenge with practical values in enzyme
technology. Temperature-sensitive copolymer chitosan-<i>graft</i>- polyÂ(<i>N</i>-isopropylacrylamide) was synthesized and
encapsulated with multimeric enzymes in the confined spaces constructed
by the W/O microemulsion. In this way, the quaternary structures of
multimeric enzymes are stabilized and the thermal stabilities of them
are enhanced. The whole process was studied and discussed. This method,
which works well for both glucose oxidase and catalase, can be developed
as a general protection strategy for multimeric enzymes
Self-Etching of Metal–Organic Framework Templates during Polydopamine Coating: Nonspherical Polydopamine Capsules and Potential Intracellular Trafficking of Metal Ions
Traditionally, containers made from
steel or other metals are not
good for making tea, probably due to the fact that polyphenol components
in tea can chelate with metal ions. A similar reason might stand behind
the observations as reported herein. During the coating of well-defined
metal–organic framework (MOF) crystalline particles with polydopamine
(PDA) via pH-induced self-polymerization of dopamine, we found that
MOF templates automatically etch off during the coating, giving rise
to nonspherical PDA capsules that inherit the morphologies of the
templates. Such self-etching of MOF templates is ascribed to the chelation
of the metal nodes of the MOFs by the catechol moieties in the PDA
layer. In addition, the self-etching of the zeolitic imidazolate framework-8
(ZIF-8) with a truncated cubic shape probably follows a crystalline
facet-dependent fashion, resulting in intermediate yolk–shell
structures with ZIF-8 cargos of various shapes inside a highly biocompatible
PDA shell. Incubation of such intermediate hybrid particles with the
cancerous HeLa cell line leads to pronounced cytotoxicity, which is
tentatively connected with the cellular internalization of the ZIF@PDA
nanoparticles because of the cell affinity of the PDA layer. Subsequently,
the continuous release of Zn<sup>2+</sup> by the self-etching of the
encapsulated ZIF-8 inside the cell increases intracellular Zn<sup>2+</sup> to a harmful level. Therefore, intracellular delivery of
metal ions is probably realized, which might offer a novel way for
cancer therapy
Thermoresponsive Chiral to Nonchiral Ordering Transformation in the Nematic Liquid-Crystal Phase of Rodlike Viruses: Turning the Survival Strategy of a Virus into Valuable Material Properties
The
current work investigates the thermoresponsive in situ chiral
to nonchiral ordering transformation of a rodlike virus in the naturally
assembled stateî—¸the chiral nematic liquid crystal (CLC) phase.
We take this as an elegant example of reconfigurable self-assembly,
through which it is possible to realize in situ transformation from
one assembled state to another without disrupting the preformed assembly
in general or going through a secondary assembling procedure of the
disassembled building blocks. The detailed investigation presented
here reveals many unique characteristics of the thermoresponsive 3D
chiral ordering of rodlike viruses induced by heat stress. The chiral
to nonchiral ordering transformation is highly reversible in the temperature
range of up to 60 °C and can be repeated many times. There exists
a critical temperature around 40 °C which is independent of the
ionic strength and virus concentration. Such reconfigurable ordering
in the CLC phase stems from the intrinsic structure change of constituent
coat proteins without disrupting the structural integrity of the virus,
as revealed by three analytical techniques targeting levels ranging
from the molecular, secondary conformation of the constituent proteins
to the whole single virus, respectively. Such structural flexibility,
also termed polymorphism, is relative to the survival strategies of
a biological organism such as the virus and can be transformed into
very precious material properties. The potential of the virus-based
CLC phase as the chiral matrix to regulate chiro-optical properties
of gold nanorods is also presented
Thermoresponsive Chiral to Nonchiral Ordering Transformation in the Nematic Liquid-Crystal Phase of Rodlike Viruses: Turning the Survival Strategy of a Virus into Valuable Material Properties
The
current work investigates the thermoresponsive in situ chiral
to nonchiral ordering transformation of a rodlike virus in the naturally
assembled stateî—¸the chiral nematic liquid crystal (CLC) phase.
We take this as an elegant example of reconfigurable self-assembly,
through which it is possible to realize in situ transformation from
one assembled state to another without disrupting the preformed assembly
in general or going through a secondary assembling procedure of the
disassembled building blocks. The detailed investigation presented
here reveals many unique characteristics of the thermoresponsive 3D
chiral ordering of rodlike viruses induced by heat stress. The chiral
to nonchiral ordering transformation is highly reversible in the temperature
range of up to 60 °C and can be repeated many times. There exists
a critical temperature around 40 °C which is independent of the
ionic strength and virus concentration. Such reconfigurable ordering
in the CLC phase stems from the intrinsic structure change of constituent
coat proteins without disrupting the structural integrity of the virus,
as revealed by three analytical techniques targeting levels ranging
from the molecular, secondary conformation of the constituent proteins
to the whole single virus, respectively. Such structural flexibility,
also termed polymorphism, is relative to the survival strategies of
a biological organism such as the virus and can be transformed into
very precious material properties. The potential of the virus-based
CLC phase as the chiral matrix to regulate chiro-optical properties
of gold nanorods is also presented
Reversible Interactions of Proteins with Mixed Shell Polymeric Micelles: Tuning the Surface Hydrophobic/Hydrophilic Balance toward Efficient Artificial Chaperones
Molecular chaperones can elegantly
fine-tune its hydrophobic/hydrophilic
balance to assist a broad spectrum of nascent polypeptide chains to
fold properly. Such precious property is difficult to be achieved
by chaperone mimicking materials due to limited control of their surface
characteristics that dictate interactions with unfolded protein intermediates.
Mixed shell polymeric micelles (MSPMs), which consist of two kinds
of dissimilar polymeric chains in the micellar shell, offer a convenient
way to fine-tune surface properties of polymeric nanoparticles. In
the current work, we have fabricated ca. 30 kinds of MSPMs with finely
tunable hydrophilic/hydrophobic surface properties. We investigated
the respective roles of thermosensitive and hydrophilic polymeric
chains in the thermodenaturation protection of proteins down to the
molecular structure. Although the three kinds of thermosensitive polymers
investigated herein can form collapsed hydrophobic domains on the
micellar surface, we found distinct capability to capture and release
unfolded protein intermediates, due to their respective affinity for
proteins. Meanwhile, in terms of the hydrophilic polymeric chains
in the micellar shell, polyÂ(ethylene glycol) (PEG) excels in assisting
unfolded protein intermediates to refold properly via interacting
with the refolding intermediates, resulting in enhanced chaperone
efficiency. However, another hydrophilic polymer-polyÂ(2-methacryloyloxyethyl
phosphorylcholine) (PMPC) severely deteriorates the chaperone efficiency
of MSPMs, due to its protein-resistant properties. Judicious combination
of thermosensitive and hydrophilic chains in the micellar shell lead
to MSPM-based artificial chaperones with optimal efficacy
Pure Anisotropic Hydrogel with an Inherent Chiral Internal Structure Based on the Chiral Nematic Liquid Crystal Phase of Rodlike Viruses
Imparting
ordered structures into otherwise amorphous hydrogels
is expected to endow these popular materials with novel multiple-stimuli
responsiveness that promises many applications. The current contribution
reports a method to fabricate pure polymeric hydrogels with an inherent
chiral internal structure by templating on the chiral nematic liquid
crystal phase of a rodlike virus. A method was developed to form macroscopically
homogeneous chiral templates by confinement induced self-assembly
in the presence of monomers, cross-linkers and initiators. Polymerization
induced gelation was performed without perturbing the elegant 3D chiral
organization of the rodlike virus bearing double bonds. Furthermore,
a suitable method was found to remove the organic virus template while
keeping the desired polymeric replica intact, resulting in a pure
polymeric hydrogel with a unique internal chiral feature that originates
from the 3D chiral ordering of the cylindrical pores left by the virus.
Multiple-stimuli responsiveness has been demonstrated and can be quantified
by the change of the pitch of the chiral feature. The chiral structure
endows the otherwise featureless hydrogel with a unique material property
that might be used as a readout signal for sensing and acts as the
basis for responsive, biomimetic nanostructured materials
Pure Anisotropic Hydrogel with an Inherent Chiral Internal Structure Based on the Chiral Nematic Liquid Crystal Phase of Rodlike Viruses
Imparting
ordered structures into otherwise amorphous hydrogels
is expected to endow these popular materials with novel multiple-stimuli
responsiveness that promises many applications. The current contribution
reports a method to fabricate pure polymeric hydrogels with an inherent
chiral internal structure by templating on the chiral nematic liquid
crystal phase of a rodlike virus. A method was developed to form macroscopically
homogeneous chiral templates by confinement induced self-assembly
in the presence of monomers, cross-linkers and initiators. Polymerization
induced gelation was performed without perturbing the elegant 3D chiral
organization of the rodlike virus bearing double bonds. Furthermore,
a suitable method was found to remove the organic virus template while
keeping the desired polymeric replica intact, resulting in a pure
polymeric hydrogel with a unique internal chiral feature that originates
from the 3D chiral ordering of the cylindrical pores left by the virus.
Multiple-stimuli responsiveness has been demonstrated and can be quantified
by the change of the pitch of the chiral feature. The chiral structure
endows the otherwise featureless hydrogel with a unique material property
that might be used as a readout signal for sensing and acts as the
basis for responsive, biomimetic nanostructured materials
Thermoresponsive Chiral to Nonchiral Ordering Transformation in the Nematic Liquid-Crystal Phase of Rodlike Viruses: Turning the Survival Strategy of a Virus into Valuable Material Properties
The
current work investigates the thermoresponsive in situ chiral
to nonchiral ordering transformation of a rodlike virus in the naturally
assembled stateî—¸the chiral nematic liquid crystal (CLC) phase.
We take this as an elegant example of reconfigurable self-assembly,
through which it is possible to realize in situ transformation from
one assembled state to another without disrupting the preformed assembly
in general or going through a secondary assembling procedure of the
disassembled building blocks. The detailed investigation presented
here reveals many unique characteristics of the thermoresponsive 3D
chiral ordering of rodlike viruses induced by heat stress. The chiral
to nonchiral ordering transformation is highly reversible in the temperature
range of up to 60 °C and can be repeated many times. There exists
a critical temperature around 40 °C which is independent of the
ionic strength and virus concentration. Such reconfigurable ordering
in the CLC phase stems from the intrinsic structure change of constituent
coat proteins without disrupting the structural integrity of the virus,
as revealed by three analytical techniques targeting levels ranging
from the molecular, secondary conformation of the constituent proteins
to the whole single virus, respectively. Such structural flexibility,
also termed polymorphism, is relative to the survival strategies of
a biological organism such as the virus and can be transformed into
very precious material properties. The potential of the virus-based
CLC phase as the chiral matrix to regulate chiro-optical properties
of gold nanorods is also presented
Ellipsoidal Colloids with a Controlled Surface Roughness via Bioinspired Surface Engineering: Building Blocks for Liquid Marbles and Superhydrophobic Surfaces
Understanding the important role
of the surface roughness of nano/colloidal
particles and harnessing them for practical applications need novel
strategies to control the particles’ surface topology. Although
there are many examples of spherical particles with a specific surface
roughness, nonspherical ones with similar surface features are rare.
The current work reports a one-step, straightforward, and bioinspired
surface engineering strategy to prepare ellipsoidal particles with
a controlled surface roughness. By manipulating the unique chemistry
inherent to the oxidation-induced self-polymerization of dopamine
into polydopamine (PDA), PDA coating of polymeric ellipsoids leads
to a library of hybrid ellipsoidal particles (PS@PDA) with a surface
that decorates with nanoscale PDA protrusions of various densities
and sizes. Together with the advantages originated from the anisotropy
of ellipsoids and rich chemistry of PDA, such a surface feature endows
these particles with some unique properties. Evaporative drying of
fluorinated PS@PDA particles produces a homogeneous coating with superhydrophobicity
that arises from the two-scale hierarchal structure of microscale
interparticle packing and nanoscale roughness of the constituent ellipsoids.
Instead of water repelling that occurs for most of the lotus leaf-like
superhydrophobic surfaces, such coating exhibits strong water adhesion
that is observed with certain species of rose pedals. In addition,
the as-prepared hybrid ellipsoids are very efficient in preparing
liquid marble-isolated droplets covered with solid particles. Such
liquid marbles can be placed onto many surfaces and might be useful
for the controllable transport and manipulation of small volumes of
liquids