14 research outputs found
Controlled Assembly of Rodlike Viruses with Polymers
A practical method to assemble rodlike tobacco mosaic virus and bacteriophage M13 with polymers was developed, which afforded a 3D core–shell composite with morphological control
Development of Polymer-Biomolecule Core-Shell Particles For Biomedical Applications
Developing efficient strategies to introduce biomolecules around polymeric nanoparticles (NPs) is critical for targeted delivery of therapeutic or diagnostic agents. Although polymeric NPs have been well established, problems such as toxicity, stability, and immunoresistance remain potential concerns. The first part of this dissertation focuses on the development of nanosized targeted drug delivery vehicle in cancer chemotherapy. The vehicle was created by the self-assembly of folate-grafted filamentous bacteriophage M13 with poly(caprolactone-b-2-vinylpyridine) while doxorubicin, the antitumor drugs, was successfully loaded in the interior of the vehicles. These particles offer unique properties of being able to selectively target tumor cells while appearing to be safe and non-toxic to normal cells. Although they have shown great prospects in many biomedical applications, less is known about the interactions between biomolecules and polymers.
The next part of the dissertation focuses on the self-assembly of proteins and polymers to create polymer-protein core-shell nanoparticles (PPCS-NPs). Several proteins with different isoelectric points and molecular weights were employed to demonstrate a versatility of our assembly method while a series of esterified derivatives of poly(2-hydroxyethyl methacrylate) (pHEMA) were synthesized to evaluate the interaction between proteins and polymers. Our data indicated that the polymers containing pyridine residues can successfully assemble with proteins, and the mechanism is mainly governed by hydrogen bonding and the hydrophobic/hydrophilic interactions. This in turn helps retaining proteins\u27 folding conformation and functionality, which are also demonstrated in the in vitro/in vivo cellular uptake of the PPCS-NPs in endothelial cells.
The last part of the dissertation focuses on the self-assembly of the bienzyme-polymer NPs. Glucose oxidase (GOX) together with horseradish peroxidase (HRP) were employed to construct bienzyme-NPs. GOX was initially used as a model enzyme to assemble with pyridine-modified pHEMA, and its enzymatic activity was shown to increase after self-assembly. When both GOX and HRP were assembled with the polymers, the activity was shown to be even greater than that of the single enzyme-polymer NPs or a free enzyme. The results indicated that NPs enhance enzymatic activity, likely due to an increase in enzyme localization, and the assembly between GOX and polymers might prevent conformational transitions of these enzymes
Enhancing Enzyme Stability by Construction of Polymer–Enzyme Conjugate Micelles for Decontamination of Organophosphate Agents
Enhancing
the stability of enzymes under different working environments
is essential if the potential of enzyme-based applications is to be
realized for nanomedicine, sensing and molecular diagnostics, and
chemical and biological decontamination. In this study, we focus on
the enzyme, organophosphorus hydrolase (OPH), which has shown great
promise for the nontoxic and noncorrosive decontamination of organophosphate
agents (OPs) as well as for therapeutics as a catalytic bioscavanger
against nerve gas poisoning. We describe a facile approach to stabilize
OPH using covalent conjugation with the amphiphilic block copolymer,
Pluronic F127, leading to the formation of F127-OPH conjugate micelles,
with the OPH on the micelle corona. SDS-PAGE and MALDI-TOF confirmed
the successful conjugation, and transmission electron microscopy (TEM)
and dynamic light scattering (DLS) revealed ∼100 nm size micelles.
The conjugates showed significantly enhanced stability and higher
activity compared to the unconjugated OPH when tested (i) in aqueous
solutions at room temperature, (ii) in aqueous solutions at higher
temperatures, (iii) after multiple freeze/thaw treatments, (iv) after
lyophilization, and (v) in the presence of organic solvents. The F127-OPH
conjugates also decontaminated paraoxon (introduced as a chemical
agent simulant) on a polystyrene film surface and on a CARC (Chemical
Agent Resistant Coating) test panel more rapidly and to a larger extent
compared to free OPH. We speculate that, in the F127-OPH conjugates
(both in the micellar form as well as in the unaggregated conjugate),
the polypropylene oxide block of the copolymer interacts with the
surface of the OPH and this confinement of the OPH reduces the potential
for enzyme denaturation and provides robustness to OPH at different
working environments. The use of such polymer–enzyme conjugate
micelles with improved enzyme stability opens up new opportunities
for numerous civilian and Warfighter applications
Facile Co-Assembly Process to Generate Core-Shell Nanoparticles with Functional Protein Corona
Enhanced activity and stability of organophosphorus hydrolase via interaction with an amphiphilic polymer
A simple approach to enhancing the activity and stability of organophosphorus hydrolase (OPH) is developed based on interactions between the hydrophobic poly(propylene oxide) (PPO) block of amphiphilic Pluronics and the enzyme. This strategy provides an efficient route to new formulations for decontaminating organophosphate neurotoxins.United States. Defense Threat Reduction Agency (Contract W911NF-07-D-0004)National Institutes of Health (U.S.) (National Institute for Biomedical Imaging and Bioengineering (U.S.) P41EB015871-27)MIT Skoltech Initiativ
Facile Co-Assembly Process to Generate Core–Shell Nanoparticles with Functional Protein Corona
A simple
and robust protocol to maintain the structural feature
of polymer–protein core–shell nanoparticles (PPCS-NPs)
is developed based on the synergistic interactions between proteins
and functional polymers. Using the self-assembly method, a broad range
of proteins can be assembled to the selective water-insoluble polymers
containing pyridine groups. The detailed analysis of the PPCS-NPs
structure was conducted using FESEM and thin-sectioned TEM. The results
illustrated that the protein molecules are located on the corona of
the PPCS-NPs. While proteins are displacing between water and polymer
to minimize the interfacial energy, the polymer offers a unique microenvironment
to maintain protein structure and conformation. The proposed mechanism
is based on a fine balance between hydrophobicity and hydrophilicity,
as well as hydrogen bonding between proteins and polymer. The PPCS-NPs
can serve as a scaffold to incorporate both glucose oxidase (GOX)
and horseradish peroxidase (HRP) onto a single particle. Such a GOX-HRP
bienzymatic system showed a ∼20% increase in activity in comparison
to the mixed free enzymes. Our method therefore provides a unique
platform to preserve protein structure and conformation and can be
extended to a number of biomolecules