Browsing by Author "Poling-Skutvik, Ryan"
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Item Analyzing Nanoparticle Dynamics in Complex Fluids Using Microscopy Techniques(2017-10-12) Perez, Ben; Smith, Maxwell; Poling-Skutvik, RyanImproving our understanding of nanoparticle dynamics in complex fluids allows for advancements in Point-of-Care diagnostics such as targeted drug delivery. Our group currently studies how a nanoparticle’s shape affects its dynamics in complex fluids. A previous study on spherical nanoparticles in complex fluids indicated that diffusivity collapses with increasing length scale (ratio of particle size to space between polymer chains) the diffusivities exceeded expected values made by bulk rheology. These two findings motivated this project.Item Orientational binding modes of reporters in a viral-nanoparticle lateral flow assay(Analyst, 2017-12) Kim, Jinsu; Poling-Skutvik, Ryan; Trabuco, Joao R. C.; Kourentzi, Katerina D.; Willson, Richard C.; Conrad, Jacinta C.Using microscopy and image analysis, we characterize binding of filamentous viral nanoparticles to a fibrous affinity matrix as models for reporter capture in a lateral flow assay (LFA). M13 bacteriophage (M13) displaying an in vivo-biotinylated peptide (AviTag) genetically fused to the M13 tail protein p3 are functionalized with fluorescent labels. We functionalize glass fiber LFA membranes with antibodies to M13, which primarily capture M13 on the major p8 coat proteins, or with avidin, which captures M13 at the biotin-functionalized tail, and compare orientational modes of reporter capture for the side- versus tip-binding recognition interactions. The number of captured M13 is greater for side-binding than for tip-binding, as expected from the number of recognition groups. Whereas two-thirds of side-bound M13 captured by an anti-M13 antibody bind immediately after colliding with the membrane, tip-bound M13 prominently exhibit three additional orientational modes that require M13 to reorient to enable binding. These results are consistent with the idea that the elongated M13 shape couples with the complex flow field in an open and disordered fibrous LFA membrane to enhance capture.Item Transport of Nanoparticles through Complex Polymeric Fluids(2018-05) Poling-Skutvik, Ryan; Krishnamoorti, Ramanan; Conrad, Jacinta C.; Palmer, Jeremy C.; Robertson, Megan L.; Ardebili, Haleh; Shaffer, Devin L.Transport of nanoparticles affects applications ranging from targeted drug delivery to enhanced oil recovery to processing of nanocomposite materials. In each of these applications, the nanoparticles must be transported through a complex fluid to reach the desired target, whether that be a cancerous tumor, the oil-water interface, or a polymer melt. For large particles, the surrounding medium is effectively homogeneous across the surface of the particle so that the transport properties can be directly related to the bulk fluid properties. For nanoparticles, however, the particle size is comparable to the length scales of heterogeneities in the fluid so that the particle dynamics decouple from bulk properties and are poorly understood. Here, we experimentally investigate how functionalized nanoparticles transport through polymer solutions as a model system for a complex, heterogeneous material using a combination of optical microscopy and scattering techniques. When the nanoparticles are comparably sized to the dissolved polymer, the nanoparticle dynamics exhibit two qualitatively different behaviors – subdiffusive on short time scales before recovering diffusive dynamics on long time scales. The long-time diffusivities are controlled by the segmental relaxations of the polymer chains over the particle surface, whereas the short time subdiffusive dynamics additionally couple to the center-of-mass dynamics of the polymer chains. In the presence of long-range interparticle interactions, the subdiffusive particle dynamics are slowed over the interparticle distance indicating that the polymer solution provides only a finite energy barrier to nanoparticle transport. This finite energy barrier can be exploited to drive the self-assembly of anisotropic nanoparticles functionalized with short-chain polymers into porous, fractal structures with controllable structural properties. For high molecular weight grafted chains, however, the dynamics of the grafted chains are confined over the distance between the grafted chains at the nanoparticle surface and affect the transport of the polymer-grafted nanoparticle through solutions of free polymer. Using the physics elucidated with this work will grant better control over the transport and dispersion of nanoparticles through complex, heterogeneous materials.Item Understanding the Dynamics of Complex Nanoparticle and Polymer Solutions Using Molecular Simulations(2023-12) Kotkar, Shivraj Bhagwatrao; Palmer, Jeremy C.; Conrad, Jacinta C.; Robertson, Megan L.; Howard, Michael P.; Poling-Skutvik, RyanUnderstanding nanoparticle dynamics in polymer solutions holds significance for drug delivery and enhanced oil recovery applications. Deviation from the generalized Stokes-Einstein relation occurs when nanoparticle and polymer sizes are comparable. We employ hybrid molecular dynamics-multiparticle collision dynamics (MD--MPCD) simulations to investigate nanoparticle dynamics in semidilute solutions of ring and linear polymers. Nanoparticle diffusivities agrees with predictions from a polymer coupling theory [Cai, Panyukov, and Rubinstein, Macromolecules 44, 7853 (2011)], indicating coupling to segmental relaxations for both polymer architectures. Short-time nanoparticle dynamics exhibit subdiffusive behavior, deviating from coupling theory, instead closely tracking polymer subdiffusive exponents. The strong coupling of nanoparticle dynamics to polymer center-of-mass motions holds for both architectures. We also explore the impact of ring polymer stiffness on nanoparticle dynamics, observing deviations from coupling theory predictions and a vanishing coupling between nanoparticle dynamics and polymer center-of-mass motions with increased stiffness. In our subsequent study, we delve into the dynamics of polymers grafted onto spherical nanoparticles. Mean-square displacements of monomers near the grafting surface show an intermediate plateau, signifying confined dynamics akin to neutron spin-echo experiment reports. This confined dynamics disappears beyond a specific radial distance from the nanoparticle surface, dependent on polymer grafting density. We demonstrate that this dynamical confinement transition adheres to theoretical predictions for the critical distance associated with the structural transition from concentrated brush regime to semidilute brush regime.