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Full-Text Articles in Engineering
An Assessment Of The Effects Of Shell Cross-Linked Nanoparticle Size, Core Composition, And Surface Pegylation On In Vivo Biodistribution, Matthew Becker
An Assessment Of The Effects Of Shell Cross-Linked Nanoparticle Size, Core Composition, And Surface Pegylation On In Vivo Biodistribution, Matthew Becker
Matthew Becker
Amphiphilic core-shell nanoparticles have drawn considerable interest in biomedical applications. The precise control over their physicochemical parameters and the ability to attach various ligands within specific domains suggest shell cross-linked (SCK) nanoparticles may be used as multi-/polyvalent scaffolds for drug delivery. In this study, the biodistribution of four SCKs, differing in size, core composition, and surface PEGylation, was evaluated. To facilitate in-vivo tracking of the SCKs, the positron-emitting radionuclide copper-64 was used. By using biodistribution and microPET imaging approaches, we found that small diameter (18 nm) SCKs possessing a polystyrene core showed the most favorable biological behavior in terms of …
Thin Film Elastic Modulus Of Degradable Tyrosine-Derived Polycarbonate Biomaterials And Their Blends, Matthew Becker
Thin Film Elastic Modulus Of Degradable Tyrosine-Derived Polycarbonate Biomaterials And Their Blends, Matthew Becker
Matthew Becker
The integrity, function, and performance of biomedical devices having thin polymeric coatings are critically dependent on the mechanical properties of the film, including the elastic modulus. In this report, the elastic moduli of several tyrosine-derived polycarbonate thin films, specifically desaminotyrosyl ethyl tyrosine polycarbonates p(DTE carbonate), an iodinated derivative p(I(2)-DTE carbonate), and several discrete blends are measured using a method based on surface wrinkling. The data shows that the elastic modulus does not vary significantly with the blend composition as the weight percentage of p(I(2)-DTE carbonate) increases for films of uniform thickness in the range of 67 to 200 nm. As …
Fabrication Of Combinatorial Polymer Scaffold Libraries, Matthew Becker
Fabrication Of Combinatorial Polymer Scaffold Libraries, Matthew Becker
Matthew Becker
We have designed a novel combinatorial research platform to help accelerate tissue engineering research. Combinatorial methods combine many samples into a single specimen to enable accelerated experimentation and discovery. The platform for fabricating combinatorial polymer scaffold libraries can be used to rapidly identify scaffold formulations that maximize tissue formation. Many approaches for screening cell-biomaterial interactions utilize a two-dimensional format such as a film or surface to present test substrates to cells. However, cells in vivo exist in a three-dimensional milieu of extracellular matrix and cells in vitro behave more naturally when cultured in a three-dimensional environment than when cultured on …
Combinatorial Methods For Tissue Engineering, Matthew Becker
Combinatorial Methods For Tissue Engineering, Matthew Becker
Matthew Becker
No abstract provided.
Length Fractionation Of Carbon Nanotubes Using Centrifugation, Matthew Becker
Length Fractionation Of Carbon Nanotubes Using Centrifugation, Matthew Becker
Matthew Becker
Scalable separation of single-walled carbon nanotubes (SWCNTs)by length and chirality is critical to the adaptation of these materials for applications. Ultracentrifugation of SWCNTs within a density gradient produces chiral separation of the NTs, and it is shown here that ultracentrifugation can also be used to produce length fractionated SWCNTs by exploiting their transient motion in response to applied centripetal acceleration.
Carbon Nanotubes: Measuring Dispersion And Length, Matthew Becker
Carbon Nanotubes: Measuring Dispersion And Length, Matthew Becker
Matthew Becker
Advanced technological uses of single-walled carbon nanotubes (SWCNTs) rely on the production of single length and chirality populations that are currently only available through liquid-phase post processing. The foundation of all of these processing steps is the attainment of individualized nanotube dispersions in solution. An understanding of the colloidal properties of the dispersed SWCNTs can then be used to design appropriate conditions for separations. In many instances nanotube size, particularly length, is especially active in determining the properties achievable in a given population, and, thus, there is a critical need for measurement technologies for both length distribution and effective separation …
Combinatorial Polymer Scaffold Libraries For Screening Cell-Biomaterial Interactions In 3d, Matthew Becker
Combinatorial Polymer Scaffold Libraries For Screening Cell-Biomaterial Interactions In 3d, Matthew Becker
Matthew Becker
We acknowledge helpful contributions from N. J. Lin, J. Sun, L. M. Pakstis, and S. Lin-Gibson (NIST). This work was supported by NIST and NIH/NIBIB R21 EB006497-01. Polymers were synthesized at Rutgers University supported by “RESBIO” – the Integrated Resource for Polymeric Biomaterials (NIH Grant P41 EB001046). This article, a contribution of the National Institute of Standards and Technology, is not subject to US copyright. Certain equipment and instruments or materials are identified in the paper to adequately specify the experimental details. Such identification does not imply recommendation by the National Institute of Standards and Technology, nor does it imply …
Length-Dependent Raman Spectroscopy Of Single-Walled Carbon Nanotubes: The Effect Of Dispersant On Defects, Matthew Becker
Length-Dependent Raman Spectroscopy Of Single-Walled Carbon Nanotubes: The Effect Of Dispersant On Defects, Matthew Becker
Matthew Becker
We compare Raman spectra from aqueous suspensions of length-separated single-walled carbon nanotubes (SWCNTs) dispersed using either polymer adsorption of single-stranded DNA or miscelle encapsulation with sodium deoxycholate surfactant. The Raman spectral features, other than the D-band, increase monotonically with nanotube length in both dispersion schemes. The intensity ratio of the disorder-induced D to G' Raman bands decays as a function of SWCNT length, proportional to 1/L, as expected for endcap defects. While the UV-vis absorption and fluorescence also increase with length for both dispersants, the fluorescence intensity is dramatically lower for DNA-wrapped SWCNTs of equal length. The similarities in the …
Pna-Directed Solution-And Surface-Assembly Of Shell Crosslinked (Sck) Nanoparticle Conjugates, Matthew Becker
Pna-Directed Solution-And Surface-Assembly Of Shell Crosslinked (Sck) Nanoparticle Conjugates, Matthew Becker
Matthew Becker
No abstract provided.
High-Content Profiling Of Cell Responsiveness To Graded Substrates Based On Combinatorially Variant Polymers, Matthew Becker
High-Content Profiling Of Cell Responsiveness To Graded Substrates Based On Combinatorially Variant Polymers, Matthew Becker
Matthew Becker
We have developed a novel approach combining high information and high throughput analysis to characterize cell adhesive responses to biomaterial substrates possessing gradients in surface topography. These gradients were fabricated by subjecting thin film blends of tyrosine-derived polycarbonates, i.e. poly(DTE carbonate) and poly(DTO carbonate) to a gradient temperature annealing protocol. Saos-2 cells engineered with a green fluorescent protein (GFP) reporter for farnesylation (GFP-f) were cultured on the gradient substrates to assess the effects of nanoscale surface topology and roughness that arise during the phase separation process on cell attachment and adhesion strength. The high throughput imaging approach allowed us to …
Peg-Hydrogels: Synthesis, Characterization, And Cell Encapsulation, Matthew Becker
Peg-Hydrogels: Synthesis, Characterization, And Cell Encapsulation, Matthew Becker
Matthew Becker
No abstract provided.
Evaluation Of Accelerated Bridge Construction Methods And Designs In The State Of Iowa, Matthew Fred Becker
Evaluation Of Accelerated Bridge Construction Methods And Designs In The State Of Iowa, Matthew Fred Becker
Matthew Becker
Accelerated bridge construction (ABC) is the general term given to a variety of approaches aimed at reducing construction durations of bridge projects. Using these approaches on bridge projects introduces a number of advantages including reduced traffic disruption and increased safety. This thesis is comprised of two papers that focus on a number of ABC projects completed in the state of Iowa in the last decade. The first paper highlights the construction aspects of these projects and gives an evaluation of the projects based on criteria related to rapid construction and gives a comparison of the project cost to non-ABC projects. …
Optical Anisotropy Of Aligned Single Wall Carbon Nanotubes, Matthew Becker
Optical Anisotropy Of Aligned Single Wall Carbon Nanotubes, Matthew Becker
Matthew Becker
The optical properties of single wall carbon nanotubes (SWCNTs) are of significant importance for a variety of applications, particularly for fractions containing well defined tube lengths and chiralities. In this work, stable suspensions of DNA wrapped SWCNTs were mechanically aligned by dispersing them in amorphous polymer films, and their intrinsic optical anisotropy measured through a combination of polarized light spectroscopy, polarized Raman spectroscopy, and small-angle neutron scattering (SANS). Conventional measures of nematic alignment in the stretched polymer films typically varied from 0.7 to 0.9. The quality of the nanotube dispersion within the centimeter scale polymer film samples was also directly …
Rheo-Optical Studies Of Carbon Nanotube Suspensions, Matthew Becker
Rheo-Optical Studies Of Carbon Nanotube Suspensions, Matthew Becker
Matthew Becker
We use a polarization-modulation technique to investigate the optical anisotropy of multi- and single-wall carbon nanotubes suspended in a variety of solvents under simple shear flow. Measurements of birefringence and dichroism are performed as a function of shear rate, tube concentration, and solvent viscosity. At fixed volume fraction, the anisotropy increases with increasing shear stress due to enhanced flow alignment. At fixed shear stress, the anisotropy increases with volume fraction due to rotational excluded-volume interactions. By considering the rotational diffusivity as a function of nanotube length, diameter, concentration, and solvent viscosity, we demonstrate a leading-order scaling relation for the optical …
Length Fractionation Of Single Wall Carbon Nanotubes Using Centrifugation, Matthew Becker
Length Fractionation Of Single Wall Carbon Nanotubes Using Centrifugation, Matthew Becker
Matthew Becker
Scalable separation of single-walled carbon nanotubes (SWCNTs)by length and chirality is critical to the adaptation of these materials for applications. Ultracentrifugation of SWCNTs within a density gradient produces chiral separation of the NTs, and it is shown here that ultracentrifugation can also be used to produce length fractionated SWCNTs by exploiting their transient motion in response to applied centripetal acceleration.
Length-Dependent Uptake Of Dna-Wrapped Single-Walled Carbon Nanotubes, Matthew Becker
Length-Dependent Uptake Of Dna-Wrapped Single-Walled Carbon Nanotubes, Matthew Becker
Matthew Becker
A length threshold for cell uptake of DNA-wrapped single-walled carbon nanotubes (SWNTs) by human lung fibroblasts (IMR90) is identified. Competitive uptake experiments with well-defined and characterized length fractions show that SWNTs above the length threshold are excluded from the cell, whereas SWNTs labeled with Cy3-derivatized DNA below the threshold are able to access the cell interior, as shown in the fluorescence image and on the cover.
Improved Methods And Standards For Telomerase Detection: Quantitative Histopathology Using Antibody Staining, Matthew Becker
Improved Methods And Standards For Telomerase Detection: Quantitative Histopathology Using Antibody Staining, Matthew Becker
Matthew Becker
Evaluation of telomerase as an early detection biomarker for cancer has been hindered by a lack of reliable methods and standards for in situ histochemical measurement. Improved histochemical methods for measuring telomerase could expedite the acceptance of telomerase as a biomarker for use in diagnostic and clinical applications. The lack of a crystal structure for telomerase coupled with high variability in the antibodies available for immunohistochemical analysis has led to confusion in the literature regarding the binding specificity of these antibodies. We have developed an automated fluorescence microscopy protocol to assess the specificity of three fluorescently labeled telomerase antibodies and …
Fluorinated Copolymer Nanoparticles For Multimodal Imaging Applications, Matthew Becker
Fluorinated Copolymer Nanoparticles For Multimodal Imaging Applications, Matthew Becker
Matthew Becker
Nanomaterials have emerged as valuable tools in biomedical imaging techniques. Here, the synthesis and characterization of a novel fluorinated nanoparticle with potential applications as an MRI contrast agent is reported. Particles were synthesized using a free radical polymerization technique. Secondary ion mass spectrometry analysis showed that the particles' surface contained fluorinated groups and nitrogen-containing groups. Solid-state NMR spectroscopy suggested the presence of two distinct fluorine resonances, which conforms to the structure of the fluorinated monomer. Ongoing studies aim to evaluate the performance of the nanoparticles as MRI contrast agents both in vitro and in vivo.
Emission-Tunable Microwave Synthesis Of Highly Luminescent Water Soluble Cdse/Zns Quantum Dots, Matthew Becker
Emission-Tunable Microwave Synthesis Of Highly Luminescent Water Soluble Cdse/Zns Quantum Dots, Matthew Becker
Matthew Becker
Water soluble CdSe/ZnS nanoparticles with emission maxima from 511 nm to 596 nm and quantum efficiencies ranging from 11% to 28% are synthesized in a facile two-step method in ambient atmospheric conditions using a commercially available microwave reactor.
Universal Gradient Substrates For Click Biofunctionalization, Matthew Becker
Universal Gradient Substrates For Click Biofunctionalization, Matthew Becker
Matthew Becker
Versatile templates for gradient immobilization of biomolecules by click chemistry are easily generated from reproducible and tunable surface energy gradients. An arginine–glycine–aspartate (RGD) peptide density gradient controls cell adhesion (see figure), and demonstrates the utility of this fabrication process for making substrates that can screen cell response to bioactive materials.
High Fidelity Detection Of Defects In Polymer Films Using Surface-Modified Nanoparticles, Matthew Becker
High Fidelity Detection Of Defects In Polymer Films Using Surface-Modified Nanoparticles, Matthew Becker
Matthew Becker
Surface defects are ubiquitous for most thin films, yet their systematic detection poses one of the most difficult challenges even to modern day technology. Polymer thin films are no exception to these problems. We address this issue by developing a novel, efficient method for the optical detection of surface topographical features using fluorescent nanoprobes, which are surface-modified CdSe quantum dots whose ability to detect surface features can be tuned via size and chemical properties. We have successfully applied this approach to detect numerous types of artificial and natural defects in polymer films including lines, pinholes, sharp edges, and chemically variant …