Browsing by Author "Landes, Christy F."
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Item Adsorption and Unfolding of a Single Protein Triggers Nanoparticle Aggregation(American Chemical Society, 2016) Dominguez-Medina, Sergio; Kisley, Lydia; Tauzin, Lawrence J.; Hoggard, Anneli; Shuang, Bo; Indrasekara, A. Swarnapali D.S.; Chen, Sishan; Wang, Lin-Yung; Derry, Paul J.; Liopo, Anton; Zubarev, Eugene R.; Landes, Christy F.; Link, StephanThe response of living systems to nanoparticles is thought to depend on the protein corona, which forms shortly after exposure to physiological fluids and which is linked to a wide array of pathophysiologies. A mechanistic understanding of the dynamic interaction between proteins and nanoparticles and thus the biological fate of nanoparticles and associated proteins is, however, often missing mainly due to the inadequacies in current ensemble experimental approaches. Through the application of a variety of single molecule and single particle spectroscopic techniques in combination with ensemble level characterization tools, we identified different interaction pathways between gold nanorods and bovine serum albumin depending on the protein concentration. Overall, we found that local changes in protein concentration influence everything from cancer cell uptake to nanoparticle stability and even protein secondary structure. We envision that our findings and methods will lead to strategies to control the associated pathophysiology of nanoparticle exposure in vivo.Item Adsorption of a Protein Monolayer via Hydrophobic Interactions Prevents Nanoparticle Aggregation under Harsh Environmental Conditions(American Chemical Society, 2013) Dominguez-Medina, Sergio; Blankenburg, Jan; Olson, Jana; Landes, Christy F.; Link, Stephan; Laboratory for NanophotonicsWe find that citrate-stabilized gold nanoparticles aggregate and precipitate in saline solutions below the NaCl concentration of many bodily fluids and blood plasma. Our experiments indicate that this is due to complexation of the citrate anions with Na+ cations in solution. A dramatically enhanced colloidal stability is achieved when bovine serum albumin is adsorbed to the gold nanoparticle surface, completely preventing nanoparticle aggregation under harsh environmental conditions where the NaCl concentration is well beyond the isotonic point. Furthermore, we explore the mechanism of the formation of this albumin "corona" and find that monolayer protein adsorption is most likely ruled by hydrophobic interactions. As for many nanotechnology-based biomedical and environmental applications, particle aggregation and sedimentation are undesirable and could substantially increase the risk of toxicological side-effects, the formation of the BSA corona presented here provides a low-cost bio-compatible strategy for nanoparticle stabilization and transport in highly ionic environments.Item Bleach Imaged Plasmon Propagation (BlIPP) of Metallic Nanoparticle Waveguides(2013-09-16) Solis, David; Link, Stephan; Landes, Christy F.; Johnson, Bruce R.The high speed transfer of information in materials with dimensions below the sub-diffraction limit is essential for future technological developments. Metallic nanoparticle (NP) waveguides serve a unique role in efficient energy transfer in this size regime. Light may be confined to metallic structures and propagate along the surface of the waveguide via propagating plasmon waves known as surface plasmon polaritons (SPPs). Plasmon propagation of energy in metallic structures is not perfect however and damping losses from the waveguide material lead to a characteristic exponential decay in the plasmon near field intensity. This decay length is known as the propagation length and serves as an excellent metric to compare various waveguide materials and structures to one another at particular excitation wavelengths. This thesis presents recent work in the development of a novel measurement technique termed bleach imaged plasmon propagation (BlIPP). BlIPP uses the photobleaching property of fluorophores and far field fluorescence microscopy to probe the near-field intensity of propagating plasmons and determine the propagation length. The experimental setup, image analysis, conditions, and application of BlIPP are developed within this thesis and an in depth review of the 1-photon photobleaching mechanism is also investigated. The BlIPP method is used to investigate long plasmon propagation lengths along straight chains of tightly packed Au NPs through the coupling of light to sub-radiant propagating modes, where radiative energy losses are suppressed. The findings of this work reveal, experimentally, the importance of small gap distances for the propagation of energy. Complex chain architectures are then explored using BlIPP measurements of tightly packed straight and bent chains of spherical silver NPs. We observe the highly efficient propagation of energy around sharp corners with no additional bending losses. The findings of this thesis demonstrate the advantages and capabilities of using BlIPP propagation length measurement. Further, BlIPP is used to reveal the advantage of coupling light to sub-radiant modes of NP chains, which demonstrate the ability to guide light efficiently across long distances and around complex structures, bringing us a step closer to the goal of applying plasmonic devices and circuitry in ultra compact opto-electronic devices.Item Charge-Dependent Transport Switching of Single Molecular Ions in a Weak Polyelectrolyte Multilayer(American Chemical Society, 2014) Tauzin, Lawrence J.; Shuang, Bo; Kisley, Lydia; Mansur, Andrea P.; Chen, Jixin; de Leon, Al; Advincula, Rigoberto C.; Landes, Christy F.The tunable nature of weak polyelectrolyte multilayers makes them ideal candidates for drug loading and delivery, water filtration, and separations, yet the lateral transport of charged molecules in these systems remains largely unexplored at the single molecule level. We report the direct measurement of the charge-dependent, pH-tunable, multimodal interaction of single charged molecules with a weak polyelectrolyte multilayer thin film, a 10 bilayer film of poly(acrylic acid) and poly(allylamine hydrochloride) PAA/PAH. Using fluorescence microscopy and single-molecule tracking, two modes of interaction were detected: (1) adsorption, characterized by the molecule remaining immobilized in a subresolution region and (2) diffusion trajectories characteristic of hopping (D ∼ 10–9 cm2/s). Radius of gyration evolution analysis and comparison with simulated trajectories confirmed the coexistence of the two transport modes in the same single molecule trajectories. A mechanistic explanation for the probe and condition mediated dynamics is proposed based on a combination of electrostatics and a reversible, pH-induced alteration of the nanoscopic structure of the film. Our results are in good agreement with ensemble studies conducted on similar films, confirm a previously-unobserved hopping mechanism for charged molecules in polyelectrolyte multilayers, and demonstrate that single molecule spectroscopy can offer mechanistic insight into the role of electrostatics and nanoscale tunability of transport in weak polyelectrolyte multilayers.Item Data Processing for Modern Microscopy: Faster, More Accurate, and More Reproducible(2016-04-22) Shuang, Bo; Landes, Christy F.Modern medicine is currently facing the challenge of improving wellness for the general public, especially the quality of later life that is threatened by aging-associated chronic conditions and diseases. These improvements are heavily dependent on scientific discovery of biological processes occurring on the nanoscale. Single-molecule super-resolution microscopy has made vital advancements to further understand disease mechanisms, revolutionize genome sequencing, and improve drug purification efficiencies. However, single-molecule techniques usually generate large amounts of complex data. Interpretation of this complex data to gather useful information requires sophisticated data processing techniques. In this thesis, several new data processing techniques are presented to extract valuable information in single-molecule data efficiently and accurately. First, maximum likelihood estimators have been proposed to calculate the diffusion coefficient for short single particle tracking trajectories, which can improve the space and time sensitivities of single particle tracking studies. The trade-off between accuracy and precision of different estimation methods is discussed to guide the selection of the developed estimation methods. Secondly, a newly developed single particle tracking package allows users to automatically process large amounts of raw single particle data to produce single-molecule tracking results. This is accomplished by a robust fitting approach that has been developed to localize single emitters to achieve roughly a 10 nm spatial resolution. Moreover, a 3D super-resolution algorithm for general 3D point spread functions has been explored, serving as the first open source program for 3D super-resolution recovery. Finally, an analysis algorithm for single-molecule Förster resonance energy transfer has been created to identify fast step transitions and determine the optimum number of states from single-molecule data. This algorithm outperforms the established cutting-edge algorithm in accuracy and speed. Overall, this thesis offers a broad range of data analysis techniques that benefit the powerful research in single-molecule studies.Item Environmental Response, Mechanisms, and Orientation of Diffusing Molecular Ions in Polyelectrolyte Thin Films(2011) Reznik, Carmen Geraldine; Landes, Christy F.; Hackerman-Welch, NormanNew electrochemical storage and conversion materials hold promise as important additions to the world's energy supply, and the growing ability to control both sequestration and transfer of charge and matter via functionally responsive materials promises to transform the field. Already, new understanding of the role played by nano-scale morphology of materials in transport function has contributed to considerable material improvements, with functional polymers possessing specific chemistry and morphology playing a key role in the future of electrochemical material applications. However, many challenges to optimizing properties still exist due to incomplete descriptions of transport. In this work, fluorescence spectroscopy and single molecule spectroscopy experimental techniques and analysis are developed and employed to reveal details of the mechanisms underpinning ion transport in structurally ordered polyelectrolyte polymer-brush membranes. The studies reveal the existence and nature of heterogeneous transport mechanisms in these polymer films, and provide a description of the dynamic association of molecular ions with the brush. It is also shown that it is possible to tune charged ion transport characteristics in the thin films by controlling the solvent pH, with an effective switching of ion transport rates in these brushes past a threshold pH value. Additionally, Monte Carlo models designed to model molecular scale interactions that give rise to experimental observables are developed to provide additional insight into the physical nature of transport processes in these materials. These models provide additional support for the conclusions of the experimental work.Item Error-based Extraction of States and Energy Landscapes from Experimental Single-Molecule Time-Series(Macmillan Publishers Limited, 2015) Taylor, J. Nicholas; Li, Chun-Biu; Cooper, David R.; Landes, Christy F.; Komatsuzaki, TamikiCharacterization of states, the essential components of the underlying energy landscapes, is one of the most intriguing subjects in single-molecule (SM) experiments due to the existence of noise inherent to the measurements. Here we present a method to extract the underlying state sequences from experimental SM time-series. Taking into account empirical error and the finite sampling of the time-series, the method extracts a steady-state network which provides an approximation of the underlying effective free energy landscape. The core of the method is the application of rate-distortion theory from information theory, allowing the individual data points to be assigned to multiple states simultaneously. We demonstrate the method's proficiency in its application to simulated trajectories as well as to experimental SM fluorescence resonance energy transfer (FRET) trajectories obtained from isolated agonist binding domains of the AMPA receptor, an ionotropic glutamate receptor that is prevalent in the central nervous system.Item Exploiting plasmons to sense interfacial changes at the nanoscale(2021-07-26) Flatebo, Charlotte; Landes, Christy F.Probing chemistry, especially at the nanoscale, provides insight into the mechanisms governing chemical reactions at interfaces and potential avenues for materials development. As a class of materials, plasmonic nanomaterials are a promising approach for probing chemistry at interfaces. When excited with an incident electric field like light, plasmonic nanomaterials exhibit localized surface plasmon resonances (LSPR). The LSPR scattering spectrum is sensitive to the size, shape and local environment of the nanoparticle. However, this sensitivity can be a limiting factor in applications of plasmonic materials in complex chemical environments. Contaminants in the environment can corrode or dissolve the nanomaterials, irreversibly changing the LSPR. The intrinsic heterogeneity of colloidally synthesized nanoparticles limits LSPR sensitivity to changes in the dielectric environment at the ensemble level. In my work, I use single-particle spectroelectrochemistry and correlated scanning electron microscopy to investigate the overall stability and utility of plasmonic nanomaterials in complex chemical environments. I demonstrate that we can utilize the plasmon to report on chemistry in complex environments and provide mechanistic insight into dissolution, polymer collapse, and future work in switchable electron density tuning in single plasmonic nanoparticles. Understanding the mechanisms governing these chemical processes at the nanoscale builds foundational science to support future technological developments in electronics, catalysis, and sensing.Item Extending single molecule fluorescence observation time by amplitude-modulated excitation(IOP Publishing, 2013) Kisley, Lydia; Chang, Wei-Shun; Cooper, David; Mansur, Andrea P.; Landes, Christy F.We present a hardware-based method that can improve single molecule fluorophore observation time by up to 1500% and super-localization by 47% for the experimental conditions used. The excitation was modulated using an acousto-optic modulator (AOM) synchronized to the data acquisition and inherent data conversion time of the detector. The observation time and precision in super-localization of four commonly used fluorophores were compared under modulated and traditional continuous excitation, including direct total internal reflectance excitation of Alexa 555 and Cy3, non-radiative Förster resonance energy transfer (FRET) excited Cy5, and direct epi-fluorescence wide field excitation of Rhodamine 6G. The proposed amplitude-modulated excitation does not perturb the chemical makeup of the system or sacrifice signal and is compatible with multiple types of fluorophores. Amplitude-modulated excitation has practical applications for any fluorescent study utilizing an instrumental setup with time-delayed detectors.Item Fast Step Transition and State Identification (STaSI) for Discrete Single-Molecule Data Analysis(American Chemical Society, 2014) Shuang, Bo; Cooper, David; Taylor, J. Nick; Kisley, Lydia; Chen, Jixin; Wang, Wenxiao; Li, Chun Biu; Komatsuzaki, Tamiki; Landes, Christy F.; Rice Quantum InstituteWe introduce a step transition and state identification (STaSI) method for piecewise constant single-molecule data with a newly derived minimum description length equation as the objective function. We detect the step transitions using the Student’s t test and group the segments into states by hierarchical clustering. The optimum number of states is determined based on the minimum description length equation. This method provides comprehensive, objective analysis of multiple traces requiring few user inputs about the underlying physical models and is faster and more precise in determining the number of states than established and cutting-edge methods for single-molecule data analysis. Perhaps most importantly, the method does not require either time-tagged photon counting or photon counting in general and thus can be applied to a broad range of experimental setups and analytes.Item Fluorescence Correlation Spectroscopy Study of Protein Transport and Dynamic Interactions with Clustered-Charge Peptide Adsorbents(Wiley-Blackwell, 2012-08) Daniels, Charlisa R.; Kisley, Lydia; Kim, Hannah; Chen, Wen-Hsiang; Poongavanam, Mohan- Vivekanandan; Reznik, Carmen; Kourentzi, Katerina; Willson, Richard C.; Landes, Christy F.Ion-exchange chromatography (IEX) relies on electrostatic interactions between the adsorbent and the adsorbate, and is used extensively in protein purification. Conventional IEX utilizes ligands that are singly charged and randomly dispersed over the adsorbent, creating a heterogeneous distribution of potential adsorption sites. Clustered-charge ion exchangers exhibit higher affinity, capacity, and selectivity than their dispersed-charge counterparts of the same total charge density. In the present work, we monitored the transport behavior of an anionic protein near clusteredcharge adsorbent surfaces using Fluorescence Correlation Spectroscopy. We can resolve protein free diffusion, hindered diffusion and association with bare glass, agarose-coated, and agaroseclustered peptide surfaces, demonstrating that this method can be used to understand and ultimately optimize clustered charge adsorbent and other surface interactions at the molecular scale.Item From tunable core-shell nanoparticles to plasmonic drawbridges: Active control of nanoparticle optical properties(AAAS, 2015) Byers, Chad P.; Zhang, Hui; Swearer, Dayne F.; Yorulmaz, Mustafa; Hoener, Benjamin S.; Huang, Da; Hoggard, Anneli; Chang, Wei-Shun; Mulvaney, Paul; Ringe, Emilie; Halas, Naomi J.; Nordlander, Peter; Link, Stephan; Landes, Christy F.The optical properties of metallic nanoparticles are highly sensitive to interparticle distance, giving rise to dramatic but frequently irreversible color changes. By electrochemical modification of individual nanoparticles and nanoparticle pairs, we induced equally dramatic, yet reversible, changes in their optical properties. We achieved plasmon tuning by oxidation-reduction chemistry of Ag-AgCl shells on the surfaces of both individual and strongly coupled Au nanoparticle pairs, resulting in extreme but reversible changes in scattering line shape. We demonstrated reversible formation of the charge transfer plasmon mode by switching between capacitive and conductive electronic coupling mechanisms. Dynamic single-particle spectroelectrochemistry also gave an insight into the reaction kinetics and evolution of the charge transfer plasmon mode in an electrochemically tunable structure. Our study represents a highly useful approach to the precise tuning of the morphology of narrow interparticle gaps and will be of value for controlling and activating a range of properties such as extreme plasmon modulation, nanoscopic plasmon switching, and subnanometer tunable gap applications.Item Generalized method to design phase masks for 3D super-resolution microscopy(Optical Society of America, 2019) Wang, Wenxiao; Ye, Fan; Shen, Hao; Moringo, Nicholas A.; Dutta, Chayan; Robinson, Jacob T.; Landes, Christy F.Point spread function (PSF) engineering by phase modulation is a novel approach to three-dimensional (3D) super-resolution microscopy, with different point spread functions being proposed for specific applications. It is often not easy to achieve the desired shape of engineered point spread functions because it is challenging to determine the correct phase mask. Additionally, a phase mask can either encode 3D space information or additional time information, but not both simultaneously. A robust algorithm for recovering a phase mask to generate arbitrary point spread functions is needed. In this work, a generalized phase mask design method is introduced by performing an optimization. A stochastic gradient descent algorithm and a Gauss-Newton algorithm are developed and compared for their ability to recover the phase masks for previously reported point spread functions. The new Gauss-Newton algorithm converges to a minimum at much higher speeds. This algorithm is used to design a novel stretching-lobe phase mask to encode temporal and 3D spatial information simultaneously. The stretching-lobe phase mask and other masks are fabricated in-house for proof-of-concept using multi-level light lithography and an optimized commercially sourced stretching-lobe phase mask (PM) is validated experimentally to encode 3D spatial and temporal information. The algorithms’ generalizability is further demonstrated by generating a phase mask that comprises four different letters at different depths.Item Generalized recovery algorithm for 3D super-resolution microscopy using rotating point spread functions(Springer Nature, 2016) Shuang, Bo; Wang, Wenxiao; Shen, Hao; Tauzin, Lawrence J.; Flatebo, Charlotte; Chen, Jianbo; Moringo, Nicholas A.; Bishop, Logan D.C.; Kelly, Kevin F.; Landes, Christy F.Super-resolution microscopy with phase masks is a promising technique for 3D imaging and tracking. Due to the complexity of the resultant point spread functions, generalized recovery algorithms are still missing. We introduce a 3D super-resolution recovery algorithm that works for a variety of phase masks generating 3D point spread functions. A fast deconvolution process generates initial guesses, which are further refined by least squares fitting. Overfitting is suppressed using a machine learning determined threshold. Preliminary results on experimental data show that our algorithm can be used to super-localize 3D adsorption events within a porous polymer film and is useful for evaluating potential phase masks. Finally, we demonstrate that parallel computation on graphics processing units can reduce the processing time required for 3D recovery. Simulations reveal that, through desktop parallelization, the ultimate limit of real-time processing is possible. Our program is the first open source recovery program for generalized 3D recovery using rotating point spread functions.Item High ionic strength narrows the population of sites participating in protein ion-exchange adsorption: A single-molecule study(Elsevier, 2014) Kisley, Lydia; Chen, Jixin; Mansur, Andrea P.; Dominguez-Medina, Sergio; Kulla, Eliona; Kang, Marci; Shuang, Bo; Kourentzi, Katerina; Poongavanam, Mohan-Vivekanandan; Dhamane, Sagar; Willson, Richard C.; Landes, Christy F.The retention and elution of proteins in ion-exchange chromatography is routinely controlled by adjusting the mobile phase salt concentration. It has repeatedly been observed, as judged from adsorption isotherms, that the apparent heterogeneity of adsorption is lower at more-eluting, higher ionic strength. Here, we present an investigation into the mechanism of this phenomenon using a single-molecule, super-resolution imaging technique called motion-blur Points Accumulation for Imaging in Nanoscale Topography (mbPAINT). We observed that the number of functional adsorption sites was smaller at high ionic strength and that these sites had reduced desorption kinetic heterogeneity, and thus narrower predicted elution profiles, for the anion-exchange adsorption of ?-lactalbumin on an agarose-supported, clustered-charge ligand stationary phase. Explanations for the narrowing of the functional population such as inter-protein interactions and protein or support structural changes were investigated through kinetic analysis, circular dichroism spectroscopy, and microscopy of agarose microbeads, respectively. The results suggest the reduction of heterogeneity is due to both electrostatic screening between the protein and ligand and tuning the steric availability within the agarose support. Overall, we have shown that single molecule spectroscopy can aid in understanding the influence of ionic strength on the population of functional adsorbent sites participating in the ion-exchange chromatographic separation of proteins.Item Improved Analysis for Determining Diffusion Coefficients from Short, Single-Molecule Trajectories with Photoblinking(American Chemical Society, 2013) Shuang, Bo; Byers, Chad P.; Kisley, Lydia; Wang, Lin-Yung; Zhao, Julia; Morimura, Hiroyuki; Link, Stephan; Landes, Christy F.; Rice Quantum InstituteTwo Maximum Likelihood Estimation (MLE) methods were developed for optimizing the analysis of single-molecule trajectories that include phenomena such as experimental noise, photoblinking, photobleaching, and translation or rotation out of the collection plane. In particular,short, single-molecule trajectories with photoblinking were studied, and our method was compared with existing analytical techniques applied to simulated data. The optimal method for various experimental cases was established, and the optimized MLE method was applied to a real experimental system: single-molecule diffusion of fluorescent molecular machines known as nanocars.Item In situ measurement of bovine serum albumin interaction with gold nanospheres(American Chemical Society, 2012) Dominguez-Medina, Sergio; McDonough, Steven; Swanglap, Pattanawit; Landes, Christy F.; Link, Stephan; Laboratory for NanophotonicsHere we present in situ observations of adsorption of bovine serum albumin (BSA) on citratestabilized gold nanospheres. We implemented scattering correlation spectroscopy as a tool to quantify changes in the nanoparticle Brownian motion resulting from BSA adsorption onto the nanoparticle surface. Protein binding was observed as an increase in the nanoparticle hydrodynamic radius. Our results indicate the formation of a protein monolayer at similar albumin concentrations as those found in human blood. Additionally, by monitoring the frequency and intensity of individual scattering events caused by single gold nanoparticles passing the observation volume, we found that BSA did not induce colloidal aggregation, a relevant result from the toxicological viewpoint. Moreover, to elucidate the thermodynamics of the gold nanoparticle-BSA association, we measured an adsorption isotherm which was best described by an anti-cooperative binding model. The number of binding sites based on this model was consistent with a BSA monolayer in its native state. In contrast, experiments using poly-ethylene glycol capped gold nanoparticles revealed no evidence for adsorption of BSA.Item Mechanism for plasmon-generated solvated electrons(PNAS, 2023) Al-Zubeidi, Alexander; Ostovar, Behnaz; Carlin, Claire C.; Li, Boxi Cam; Lee, Stephen A.; Chiang, Wei-Yi; Gross, Niklas; Dutta, Sukanya; Misiura, Anastasiia; Searles, Emily K.; Chakraborty, Amrita; Roberts, Sean T.; Dionne, Jennifer A.; Rossky, Peter J.; Landes, Christy F.; Link, Stephan; Center for Adapting Flaws into FeaturesSolvated electrons are powerful reducing agents capable of driving some of the most energetically expensive reduction reactions. Their generation under mild and sustainable conditions remains challenging though. Using near-ultraviolet irradiation under low-intensity one-photon conditions coupled with electrochemical and optical detection, we show that the yield of solvated electrons in water is increased more than 10 times for nanoparticle-decorated electrodes compared to smooth silver electrodes. Based on the simulations of electric fields and hot carrier distributions, we determine that hot electrons generated by plasmons are injected into water to form solvated electrons. Both yield enhancement and hot carrier production spectrally follow the plasmonic near-field. The ability to enhance solvated electron yields in a controlled manner by tailoring nanoparticle plasmons opens up a promising strategy for exploiting solvated electrons in chemical reactions.Item Mechanistic Understanding of the Phosphorylation-Induced Conformational Rigidity at the AMPA Receptor C-terminal Domain(American Chemical Society, 2019) Chatterjee, Sudeshna; Dutta, Chayan; Carrejo, Nicole C.; Landes, Christy F.Phosphorylation at the intracellular C-terminal domain (CTD) of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors induces conformational rigidity. Such intracellular alterations to the AMPA receptor influence its functional responses, which are involved in multiple synaptic processes and neuronal signaling. The structure of the CTD still remains unresolved, which poses challenges toward providing a mechanism for the process of phosphorylation and deciphering the role of each phosphorylation step in causing the resultant conformational behavior. Herein, we utilize smFRET spectroscopy to understand the mechanism of phosphorylation, with the help of strategic point mutations that mimic phosphorylation. Our results reveal that first, phosphorylation at three target sites (S818, S831, and T840) is necessary for the change in the secondary structure of the existing disordered native sequence. Also, the results suggest that the formation of the tertiary structure through electrostatic interaction involving one specific phosphorylation site (S831) stabilizes the structure and renders conformational rigidity.Item Molecular Approaches to Chromatography Using Single Molecule Spectroscopy(American Chemical Society, 2015) Kisley, Lydia; Landes, Christy F.; Rice Quantum Institute