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You searched for +publisher:"Wayne State University" +contributor:("Ashis Mukhopadhyay"). Showing records 1 – 3 of 3 total matches.

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Wayne State University

1. Omari, Rami Ahmad Saleh. Dynamics of nanoparticles in complex fluids.

Degree: PhD, Physics and Astronomy, 2011, Wayne State University

Soft matter is a subfield of condensed matter including polymers, colloidal dispersions, surfactants, and liquid crystals. These materials are familiar from our everyday life- glues, paints, soaps, and plastics are examples of soft materials. Many phenomena in these systems have the same underlying physical mechanics. Moreover, it has been recognized that combinations of these systems, like for example polymers and colloids, exhibit new properties which are found in each system separately. These mixed systems have a higher degree of complexity than the separate systems. In order to understand their behavior, knowledge from each subfields of soft matter has to be put together. One of these complex systems is the mixture of nanoparticles with macromolecules such as polymers, proteins, etc. Understanding the interactions in these systems is essential for solving various problems in technological and medical fields, such as developing high performance polymeric materials, chromatography, and drug delivery vehicles. The author of this dissertation investigates fundemental soft matter systems, including colloid dispersions in polymer solutions and binary mixture. The diffusion of gold nanoparticles in semidilute and entangled solutions of polystyrene (PS) in toluene were studied using fluctuation correlation spectroscopy (FCS). In our experiments, the particle radius (R ≈ 2.5 nm) was much smaller compared to the radius of gyration of the chain but comparable to the average mesh size of the fluctuating polymer network. The diffusion coefficient (D) of the particles decreased monotonically with polymer concentration and it can be fitted with a stretched exponential function. At high concentration of the polymer, a clear subdiffusive motion of the particles was observed. The results were compared with the diffusion of free dyes, which showed normal diffusive behavior for all concentrations. In another polymer solution, Poly ethylene glycol (PEG) in water, the diffusion of the gold nanoparticles depends on the dimentionlesss length scale R/ξ, where R is the radius of the nanoparticle and ξ is the average mesh size of the fluctuating polymer network. FCS were used to study the critical adsorption on curved surfaces by utilizing spherical nanoparticles immersed in a critical binary liquid mixture of 2,6 lutidine + water. The temperature dependence of the adsorbed film thickness and excess adsorption was determined from FCS measurements of the enlarged effective hydrodynamic radius of the particles. Our results indicated that the adsorbed film thickness is of the order of correlation length associated with concentration fluctuations. The excess adsorption per unit area increases following a power law in reduced temperature with an exponent of -1, which is the mean-field value for the bulk susceptibility exponent. The kinetics of adsorption of gold nanoparticles in polymer solutions on silicon substrate was studied using ellipsometry by measuring the thickness of the adsorbed… Advisors/Committee Members: Ashis Mukhopadhyay.

Subjects/Keywords: Colloidal Dispersions; Critical Adsorption; Diffusion; Ellipsometry; Fluorescence Correlation Spectroscopy; Polymers; Condensed Matter Physics

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APA (6th Edition):

Omari, R. A. S. (2011). Dynamics of nanoparticles in complex fluids. (Doctoral Dissertation). Wayne State University. Retrieved from https://digitalcommons.wayne.edu/oa_dissertations/326

Chicago Manual of Style (16th Edition):

Omari, Rami Ahmad Saleh. “Dynamics of nanoparticles in complex fluids.” 2011. Doctoral Dissertation, Wayne State University. Accessed September 26, 2020. https://digitalcommons.wayne.edu/oa_dissertations/326.

MLA Handbook (7th Edition):

Omari, Rami Ahmad Saleh. “Dynamics of nanoparticles in complex fluids.” 2011. Web. 26 Sep 2020.

Vancouver:

Omari RAS. Dynamics of nanoparticles in complex fluids. [Internet] [Doctoral dissertation]. Wayne State University; 2011. [cited 2020 Sep 26]. Available from: https://digitalcommons.wayne.edu/oa_dissertations/326.

Council of Science Editors:

Omari RAS. Dynamics of nanoparticles in complex fluids. [Doctoral Dissertation]. Wayne State University; 2011. Available from: https://digitalcommons.wayne.edu/oa_dissertations/326


Wayne State University

2. Alam, Sharmine. Dynamics Of Anisotropic Gold Nanopartilces In Synthetic And Biopolymer Solutions.

Degree: PhD, Physics and Astronomy, 2015, Wayne State University

Soft matter is a subfield of condensed matter physics including systems such as polymers, colloids, amphiphiles and liquid crystals. Understanding their interaction and dynamics is essential for many interdisciplinary fields of study as well as important for technological advancements. We used gold nanorods (AuNRs) to investigate the length-scale dependent dynamics in semidilute polymer solutions, their conjugation and interaction with a protein bovine serum albumin (BSA), and the effect of shape anisotropy on the dynamics within a crowded solution of spheres. Multiphoton fluctuation correlation spectroscopy (MP-FCS) technique was used to investigate the translation and rotational diffusion of AuNRs. For polymer solutions, we determined the nanoviscosity experienced by the rods from the measured diffusion coefficient. Our results showed the importance of microscopic friction in determing the particle dynamics. In BSA solutions, we observed a submonolayer formation at the AuNRs surface, which indicates loss of protein native conformation. For rod – sphere mixture, our results indicated significant diffusional anisotropy for translational motion, whereas the rotation of the rods closely followed the ‘caging theory’. Advisors/Committee Members: Ashis Mukhopadhyay.

Subjects/Keywords: Physics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Alam, S. (2015). Dynamics Of Anisotropic Gold Nanopartilces In Synthetic And Biopolymer Solutions. (Doctoral Dissertation). Wayne State University. Retrieved from https://digitalcommons.wayne.edu/oa_dissertations/1330

Chicago Manual of Style (16th Edition):

Alam, Sharmine. “Dynamics Of Anisotropic Gold Nanopartilces In Synthetic And Biopolymer Solutions.” 2015. Doctoral Dissertation, Wayne State University. Accessed September 26, 2020. https://digitalcommons.wayne.edu/oa_dissertations/1330.

MLA Handbook (7th Edition):

Alam, Sharmine. “Dynamics Of Anisotropic Gold Nanopartilces In Synthetic And Biopolymer Solutions.” 2015. Web. 26 Sep 2020.

Vancouver:

Alam S. Dynamics Of Anisotropic Gold Nanopartilces In Synthetic And Biopolymer Solutions. [Internet] [Doctoral dissertation]. Wayne State University; 2015. [cited 2020 Sep 26]. Available from: https://digitalcommons.wayne.edu/oa_dissertations/1330.

Council of Science Editors:

Alam S. Dynamics Of Anisotropic Gold Nanopartilces In Synthetic And Biopolymer Solutions. [Doctoral Dissertation]. Wayne State University; 2015. Available from: https://digitalcommons.wayne.edu/oa_dissertations/1330

3. Kohli, Indermeet. Diffusion Of Gold Nanoparticles In Synthetic And Biopolymer Solutions.

Degree: PhD, Physics and Astronomy, 2013, Wayne State University

Soft matter systems of colloidal particles, polymers, amphiphiles and liquid crystals are ubiquitous in our everyday life. Food, plastics, soap and even human body is comprised of soft materials. Research conducted to understand the behavior of these soft matter systems at molecular level is essential for many interdisciplinary fields of study as well as important for many technological applications. We used gold nanoparticles (Au NPs) to investigate the length-scale dependent dynamics in semidilute poly(ethylene glycol) (PEG)-water, bovine serum albumin (BSA)-phosphate buffer, dextran and particulate solutions. In case of PEG-water solutions, fluctuation correlation spectroscopy was used to measure the diffusion coefficients (D) of the NPs as a function of their radius, Ro (2.5-10 nm), PEG volume fraction 0-0.37, and molecular weight, Mw (5 kg/mol and 35 kg/mol). Our results indicate that the radius of gyration, Rg of the polymer chain is the crossover length scale for the NPs experiencing nanoviscosity or macroviscosity. In BSA-phosphate buffer solutions, we observed a monolayer formation at the NP surface with a thickness of 3.8 nm. The thickness of the adsorbed layer was independent of NP size. Best fit was obtained by the anticooperative binding model with the Hill coefficient of n = 0.63. Dissociation constant (KD) increased with particle size indicating stronger interaction of BSA with smaller sized NPs. We also contrasted the diffusion of gold nanoparticles (AuNPs) in crowded solutions of randomly branched polymer (dextran) and rigid, spherical particles (silica) to understand the roles played by the probe size and structure of the crowding agent in determining the probe diffusion. AuNPs of two different sizes (2.5 nm & 10 nm), dextran of molecular weight 70 kDa and silica particles of radius 10 nm were used. Our results indicated that the AuNP diffusion can be described using the bulk viscosity of the matrix and hydrodynamically dextran behaved similar to soft colloid. In all situations, we observed normal diffusion except for 2.5 nm sized AuNP particles in dextran solution at higher volume fraction. This was caused by transient trapping of particles within the random branches. The results showed the importance of macromolecular architecture in determining the transport properties in intracellular matrix and in cells with spiny dendrites. Advisors/Committee Members: ASHIS MUKHOPADHYAY.

Subjects/Keywords: BOVINE SERUM ALBUMIN; DEXTRAN; FCS; GOLD NANOPARTICLES; LUDOX; POLYETHYLENE GLYCOL; Condensed Matter Physics; Physics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Kohli, I. (2013). Diffusion Of Gold Nanoparticles In Synthetic And Biopolymer Solutions. (Doctoral Dissertation). Wayne State University. Retrieved from https://digitalcommons.wayne.edu/oa_dissertations/777

Chicago Manual of Style (16th Edition):

Kohli, Indermeet. “Diffusion Of Gold Nanoparticles In Synthetic And Biopolymer Solutions.” 2013. Doctoral Dissertation, Wayne State University. Accessed September 26, 2020. https://digitalcommons.wayne.edu/oa_dissertations/777.

MLA Handbook (7th Edition):

Kohli, Indermeet. “Diffusion Of Gold Nanoparticles In Synthetic And Biopolymer Solutions.” 2013. Web. 26 Sep 2020.

Vancouver:

Kohli I. Diffusion Of Gold Nanoparticles In Synthetic And Biopolymer Solutions. [Internet] [Doctoral dissertation]. Wayne State University; 2013. [cited 2020 Sep 26]. Available from: https://digitalcommons.wayne.edu/oa_dissertations/777.

Council of Science Editors:

Kohli I. Diffusion Of Gold Nanoparticles In Synthetic And Biopolymer Solutions. [Doctoral Dissertation]. Wayne State University; 2013. Available from: https://digitalcommons.wayne.edu/oa_dissertations/777

.