Matching Items (27)
Description
Recent breakthroughs in optical scattering-based imaging have enabledvisualization of entities as small as single proteins. Leveraging our innovation, Surface Enhanced Scattering Microscopy (SESM), detection of single protein binding kinetics and single DNA conformational changes have been achieved, showcasing the feasibility of single molecule imaging. In this dissertation, I aim to harness the potential of SESM and extend its relevance in the biomedical realm. My first goal is to conduct multiplexed protein detection and parallel binding kinetics analysis with label-free digital single- molecule counting. My second goal is focused on accurate quantification of cell force. An elastic model has been developed to quantify the cell-substrate interactions and have continuously tracked cell force evolutions upon small-molecule drugs (for example, acetylcholine) stimulation, achieving a temporal resolution of approximately 60 ms over the course of 30 min without attenuating the signals. The third goal is to achieve real- time tracking of DNA self-assembly dynamics. I have demonstrated SESM's capability to image individual DNA origami monomers and established an on-chip temperature annealing system to monitor the real-time progression of DNA self-assembly. The applications of the imaging method, spanning single proteins, single DNA origami, and single cells, are poised to impact the field of biology
ContributorsZhou, Xinyu (Author) / Wang, Shaopeng (Thesis advisor) / Nikkhah, Mehdi (Committee member) / Lindsay, Stuart (Committee member) / Presse, Steve (Committee member) / Wang, Xiao (Committee member) / Arizona State University (Publisher)
Created2024
Description
Cardiovascular diseases are the number one cause of death worldwide. Cardiac biomarkers can provide objective and quantitative information to facilitate early diagnosis and guide treatment of cardiovascular diseases. Even though a variety of methods have been developed for cardiac biomarker detection, a point-of-care testing (POCT) for cardiac biomarkers with high sensitivity, specificity and precision is still missing. To fulfil this unmet need, novel digital biosensing methods based on optical imaging and nanomaterials are developed in this dissertation for high-sensitivity POCT of cardiac biomarkers.First, a high-sensitivity and POC-compatible optical imaging-based digital immunoassay is developed for rapid detection of low-abundance biomarkers. This technology was established on a model analyte IL-6 and can be adapted to various other protein targets. The digital immunoassay was also utilized as the reference method for evaluating the digital nanobiosensors developed afterwards.
Second, a microfluidic digital nanobiosensor (MDNB) is developed for POC-compatible detection of heart failure biomarker NT-proBNP from 7 µL of whole blood. Using the MDNB, detection in a clinically relevant concentration range was achieved with a 10-minute assay time. With a high potential utility in outpatient and possibly even home settings, the MDNB could become a POC device for decentralized detection of NT-proBNP to assist heart failure patient management.
Lastly, the development of a digital immunogold-linked apta-sorbent assay (DILASA) for rapid high-sensitivity detection of heart attack biomarker cardiac troponin is introduced. Reliable detection of 10 ng/L cTnT in human plasma was achieved with a 15-minute assay time using DILASA. It is expected that with further optimization and development, DILASA will be a promising candidate approach for realizing a high-sensitivity POCT of cTnT.
ContributorsChen, Chao (Author) / Wang, Shaopeng (Thesis advisor) / Snozek, Christine (Committee member) / Pizziconi, Vincent (Committee member) / Vernon, Brent (Committee member) / Weaver, Jessica (Committee member) / Arizona State University (Publisher)
Created2024
Description
Measuring molecular interaction with membrane proteins is critical for understanding cellular functions, validating biomarkers and screening drugs. Despite the importance, developing such a capability has been a difficult challenge, especially for small molecules binding to membrane proteins in their native cellular environment. The current mainstream practice is to isolate membrane proteins from the cell membranes, which is difficult and often lead to the loss of their native structures and functions. In this thesis, novel detection methods for in situ quantification of molecular interactions with membrane proteins are described.
First, a label-free surface plasmon resonance imaging (SPRi) platform is developed for the in situ detection of the molecular interactions between membrane protein drug target and its specific antibody drug molecule on cell surface. With this method, the binding kinetics of the drug-target interaction is quantified for drug evaluation and the receptor density on the cell surface is also determined.
Second, a label-free mechanically amplification detection method coupled with a microfluidic device is developed for the detection of both large and small molecules on single cells. Using this method, four major types of transmembrane proteins, including glycoproteins, ion channels, G-protein coupled receptors (GPCRs) and tyrosine kinase receptors on single whole cells are studied with their specific drug molecules. The basic principle of this method is established by developing a thermodynamic model to express the binding-induced nanometer-scale cellular deformation in terms of membrane protein density and cellular mechanical properties. Experiments are carried out to validate the model.
Last, by tracking the cell membrane edge deformation, molecular binding induced downstream event – granule exocytosis is measured with a dual-optical imaging system. Using this method, the single granule exocytosis events in single cells are monitored and the temporal-spatial distribution of the granule fusion-induced cell membrane deformation are mapped. Different patterns of granule release are resolved, including multiple release events occurring close in time and position. The label-free cell membrane deformation tracking method was validated with the simultaneous fluorescence recording. And the simultaneous cell membrane deformation detection and fluorescence recording allow the study of the propagation of the granule release-induced membrane deformation along cell surfaces.
First, a label-free surface plasmon resonance imaging (SPRi) platform is developed for the in situ detection of the molecular interactions between membrane protein drug target and its specific antibody drug molecule on cell surface. With this method, the binding kinetics of the drug-target interaction is quantified for drug evaluation and the receptor density on the cell surface is also determined.
Second, a label-free mechanically amplification detection method coupled with a microfluidic device is developed for the detection of both large and small molecules on single cells. Using this method, four major types of transmembrane proteins, including glycoproteins, ion channels, G-protein coupled receptors (GPCRs) and tyrosine kinase receptors on single whole cells are studied with their specific drug molecules. The basic principle of this method is established by developing a thermodynamic model to express the binding-induced nanometer-scale cellular deformation in terms of membrane protein density and cellular mechanical properties. Experiments are carried out to validate the model.
Last, by tracking the cell membrane edge deformation, molecular binding induced downstream event – granule exocytosis is measured with a dual-optical imaging system. Using this method, the single granule exocytosis events in single cells are monitored and the temporal-spatial distribution of the granule fusion-induced cell membrane deformation are mapped. Different patterns of granule release are resolved, including multiple release events occurring close in time and position. The label-free cell membrane deformation tracking method was validated with the simultaneous fluorescence recording. And the simultaneous cell membrane deformation detection and fluorescence recording allow the study of the propagation of the granule release-induced membrane deformation along cell surfaces.
ContributorsZhang, Fenni (Author) / Tao, Nongjian (Thesis advisor) / Chae, Junseok (Committee member) / Borges, Chad (Committee member) / Jing, Tianwei (Committee member) / Wang, Shaopeng (Committee member) / Arizona State University (Publisher)
Created2018
Description
Proteins play a central role to human body and biological activities. As powerful tools for protein detections, many surface plasmon resonance based techniques have been developed to enhance the sensitivity. However, sensitivity is not the only final goal. As a biosensor, four things really matter: sensitivity, specificity, resolution (temporal/spatial) and throughput.
This dissertation presents several works on developing novel plasmonic based techniques for protein detections on the last two aspects to extend the application field. A fast electrochemically controlled plasmonic detection technique is first developed with the capability of monitoring electrochemical signal with nanosecond response time. The study reveals that the conformational gating of electron transfer in a redox protein (cytochrome c) takes place over a broad range of time scales (sub-µs to ms). The second platform integrates ultra-low volume piezoelectric liquid dispensing and plasmonic imaging detection to monitor different protein binding processes simultaneously with low sample cost. Experiment demonstrates the system can observe binding kinetics in 10×10 microarray of 6 nL droplet, with variations of kinetic rate constants among spots less than ±5%. A focused plasmonic imaging system with bi-cell algorithm is also proposed for spatial resolution enhancement. The two operation modes, scanning mode and focus mode, can be applied for different purposes. Measurement of bacterial aggregation demonstrates the higher spatial resolution. Detections of polystyrene beads binding and 50 nm gold nanoparticles oscillation show a high signal to noise ratio of the system.
The real properties of protein rely on its dynamic personalities. The above works shed light upon fast and high throughput detection of protein kinetics, and enable more applications for plasmonic imaging techniques. It is anticipated that such methods will help to invoke a new surge to unveil the mysteries of biological activities and chemical process.
This dissertation presents several works on developing novel plasmonic based techniques for protein detections on the last two aspects to extend the application field. A fast electrochemically controlled plasmonic detection technique is first developed with the capability of monitoring electrochemical signal with nanosecond response time. The study reveals that the conformational gating of electron transfer in a redox protein (cytochrome c) takes place over a broad range of time scales (sub-µs to ms). The second platform integrates ultra-low volume piezoelectric liquid dispensing and plasmonic imaging detection to monitor different protein binding processes simultaneously with low sample cost. Experiment demonstrates the system can observe binding kinetics in 10×10 microarray of 6 nL droplet, with variations of kinetic rate constants among spots less than ±5%. A focused plasmonic imaging system with bi-cell algorithm is also proposed for spatial resolution enhancement. The two operation modes, scanning mode and focus mode, can be applied for different purposes. Measurement of bacterial aggregation demonstrates the higher spatial resolution. Detections of polystyrene beads binding and 50 nm gold nanoparticles oscillation show a high signal to noise ratio of the system.
The real properties of protein rely on its dynamic personalities. The above works shed light upon fast and high throughput detection of protein kinetics, and enable more applications for plasmonic imaging techniques. It is anticipated that such methods will help to invoke a new surge to unveil the mysteries of biological activities and chemical process.
ContributorsWang, Yan (Author) / Tao, Nongjian (Thesis advisor) / Chae, Junseok (Committee member) / Goryll, Michael (Committee member) / Wang, Shaopeng (Committee member) / Arizona State University (Publisher)
Created2018
Description
Signal transduction networks comprising protein-protein interactions (PPIs) mediate homeostatic, diseased, and therapeutic cellular responses. Mapping these networks has primarily focused on identifying interactors, but less is known about the interaction affinity, rates of interaction or their regulation. To better understand the extent of the annotated human interactome, I first examined > 2500 protein interactions within the B cell receptor (BCR) signaling pathway using a current, cutting-edge bioluminescence-based platform called “NanoBRET” that is capable of analyzing transient and stable interactions in high throughput. Eighty-three percent (83%) of the detected interactions have not been previously reported, indicating that much of the BCR pathway is still unexplored. Unfortunately, NanoBRET, as with all other high throughput methods, cannot determine binding kinetics or affinities. To address this shortcoming, I developed a hybrid platform that characterizes > 400 PPIs quantitatively and simultaneously in < 1 hour by combining the high throughput and flexible nature of nucleic programmable protein arrays (NAPPA) with the quantitative abilities of surface plasmon resonance imaging (SPRi). NAPPA-SPRi was then used to study the kinetics and affinities of > 12,000 PPIs in the BCR signaling pathway, revealing unique kinetic mechanisms that are employed by proteins, phosphorylation and activation states to regulate PPIs. In one example, activation of the GTPase RAC1 with nonhydrolyzable GTP-γS minimally affected its binding affinities with phosphorylated proteins but increased, on average, its on- and off-rates by 4 orders of magnitude for one-third of its interactions. In contrast, this phenomenon occurred with virtually all unphosphorylated proteins. The majority of the interactions (85%) were novel, sharing 40% of the same interactions as NanoBRET as well as detecting 55% more interactions than NanoBRET. In addition, I further validated four novel interactions identified by NAPPA-SPRi using SDS-PAGE migration and Western blot analyses. In one case, we have the first evidence of a direct enzyme-substrate interaction between two well-known proto-oncogenes that are abnormally regulated in > 30% of cancers, PI3K and MYC. Herein, PI3K is demonstrated to phosphorylate MYC at serine 62, a phosphosite that increases the stability of MYC. This study provides valuable insight into how PPIs, phosphorylation, and GTPase activation regulate the BCR signal transduction pathway. In addition, these methods could be applied toward understanding other signaling pathways, pathogen-host interactions, and the effect of protein mutations on protein interactions.
ContributorsPetritis, Brianne Ogata (Author) / LaBaer, Joshua (Thesis advisor) / Lake, Douglas (Committee member) / Wang, Shaopeng (Committee member) / Arizona State University (Publisher)
Created2018
Description
Mechanical properties of cells are important in maintaining physiological functions of biological systems. Quantitative measurement and analysis of mechanical properties can help understand cellular mechanics and its functional relevance and discover physical biomarkers for diseases monitoring and therapeutics.
This dissertation presents a work to develop optical methods for studying cell mechanics which encompasses four applications. Surface plasmon resonance microscopy based optical method has been applied to image intracellular motions and cell mechanical motion. This label-free technique enables ultrafast imaging with extremely high sensitivity in detecting cell deformation. The technique was first applied to study intracellular transportation. Organelle transportation process and displacement steps of motor protein can be tracked using this method. The second application is to study heterogeneous subcellular membrane displacement induced by membrane potential (de)polarization. The application can map the amplitude and direction of cell deformation. The electromechanical coupling of mammalian cells was also observed. The third application is for imaging electrical activity in single cells with sub-millisecond resolution. This technique can fast record actions potentials and also resolve the fast initiation and propagation of electromechanical signals within single neurons. Bright-field optical imaging approach has been applied to the mechanical wave visualization that associated with action potential in the fourth application. Neuron-to-neuron viability of membrane displacement was revealed and heterogeneous subcellular response was observed.
All these works shed light on the possibility of using optical approaches to study millisecond-scale and sub-nanometer-scale mechanical motions. These studies revealed ultrafast and ultra-small mechanical motions at the cellular level, including motor protein-driven motions and electromechanical coupled motions. The observations will help understand cell mechanics and its biological functions. These optical approaches will also become powerful tools for elucidating the interplay between biological and physical functions.
This dissertation presents a work to develop optical methods for studying cell mechanics which encompasses four applications. Surface plasmon resonance microscopy based optical method has been applied to image intracellular motions and cell mechanical motion. This label-free technique enables ultrafast imaging with extremely high sensitivity in detecting cell deformation. The technique was first applied to study intracellular transportation. Organelle transportation process and displacement steps of motor protein can be tracked using this method. The second application is to study heterogeneous subcellular membrane displacement induced by membrane potential (de)polarization. The application can map the amplitude and direction of cell deformation. The electromechanical coupling of mammalian cells was also observed. The third application is for imaging electrical activity in single cells with sub-millisecond resolution. This technique can fast record actions potentials and also resolve the fast initiation and propagation of electromechanical signals within single neurons. Bright-field optical imaging approach has been applied to the mechanical wave visualization that associated with action potential in the fourth application. Neuron-to-neuron viability of membrane displacement was revealed and heterogeneous subcellular response was observed.
All these works shed light on the possibility of using optical approaches to study millisecond-scale and sub-nanometer-scale mechanical motions. These studies revealed ultrafast and ultra-small mechanical motions at the cellular level, including motor protein-driven motions and electromechanical coupled motions. The observations will help understand cell mechanics and its biological functions. These optical approaches will also become powerful tools for elucidating the interplay between biological and physical functions.
ContributorsYang, Yunze (Author) / Tao, Nongjian (Thesis advisor) / Wang, Shaopeng (Committee member) / Goryll, Michael (Committee member) / Si, Jennie (Committee member) / Arizona State University (Publisher)
Created2016
Description
Detection of molecular interactions is critical for understanding many biological processes, for detecting disease biomarkers, and for screening drug candidates. Fluorescence-based approach can be problematic, especially when applied to the detection of small molecules. Various label-free techniques, such as surface plasmon resonance technique are sensitive to mass, making it extremely challenging to detect small molecules. In this thesis, novel detection methods for molecular interactions are described.
First, a simple detection paradigm based on reflectance interferometry is developed. This method is simple, low cost and can be easily applied for protein array detection.
Second, a label-free charge sensitive optical detection (CSOD) technique is developed for detecting of both large and small molecules. The technique is based on that most molecules relevant to biomedical research and applications are charged or partially charged. An optical fiber is dipped into the well of a microplate. It detects the surface charge of the fiber, which does not decrease with the size (mass) of the molecule, making it particularly attractive for studying small molecules.
Third, a method for mechanically amplification detection of molecular interactions (MADMI) is developed. It provides quantitative analysis of small molecules interaction with membrane proteins in intact cells. The interactions are monitored by detecting a mechanical deformation in the membrane induced by the molecular interactions. With this novel method small molecules and membrane proteins interaction in the intact cells can be detected. This new paradigm provides mechanical amplification of small interaction signals, allowing us to measure the binding kinetics of both large and small molecules with membrane proteins, and to analyze heterogeneous nature of the binding kinetics between different cells, and different regions of a single cell.
Last, by tracking the cell membrane edge deformation, binding caused downstream event – granule secretory has been measured. This method focuses on the plasma membrane change when granules fuse with the cell. The fusion of granules increases the plasma membrane area and thus the cell edge expands. The expansion is localized at the vesicle release location. Granule size was calculated based on measured edge expansion. The membrane deformation due to the granule release is real-time monitored by this method.
First, a simple detection paradigm based on reflectance interferometry is developed. This method is simple, low cost and can be easily applied for protein array detection.
Second, a label-free charge sensitive optical detection (CSOD) technique is developed for detecting of both large and small molecules. The technique is based on that most molecules relevant to biomedical research and applications are charged or partially charged. An optical fiber is dipped into the well of a microplate. It detects the surface charge of the fiber, which does not decrease with the size (mass) of the molecule, making it particularly attractive for studying small molecules.
Third, a method for mechanically amplification detection of molecular interactions (MADMI) is developed. It provides quantitative analysis of small molecules interaction with membrane proteins in intact cells. The interactions are monitored by detecting a mechanical deformation in the membrane induced by the molecular interactions. With this novel method small molecules and membrane proteins interaction in the intact cells can be detected. This new paradigm provides mechanical amplification of small interaction signals, allowing us to measure the binding kinetics of both large and small molecules with membrane proteins, and to analyze heterogeneous nature of the binding kinetics between different cells, and different regions of a single cell.
Last, by tracking the cell membrane edge deformation, binding caused downstream event – granule secretory has been measured. This method focuses on the plasma membrane change when granules fuse with the cell. The fusion of granules increases the plasma membrane area and thus the cell edge expands. The expansion is localized at the vesicle release location. Granule size was calculated based on measured edge expansion. The membrane deformation due to the granule release is real-time monitored by this method.
ContributorsGuan, Yan (Author) / Tao, Nongjian (Thesis advisor) / LaBaer, Joshua (Committee member) / Goryll, Michael (Committee member) / Wang, Shaopeng (Committee member) / Arizona State University (Publisher)
Created2015
Description
Antibiotic resistant bacteria are a worldwide epidemic threatening human survival. Antimicrobial susceptibility tests (ASTs) are important for confirming susceptibility to empirical antibiotics and detecting resistance in bacterial isolates. Current ASTs are based on bacterial culturing, which take 2-14 days to complete depending on the microbial growth rate. Considering the high mortality and morbidity rates for most acute infections, such long time frames are clinically impractical and pose a huge risk to a patient's life. A faster AST will reduce morbidity and mortality rates, as well as help healthcare providers, administer narrow spectrum antibiotics at the earliest possible treatment stage.
In this dissertation, I developed a nonculture-based AST using an imaging and cell tracking technology. I track individual Escherichia coli O157:H7 (E. coli O157:H7) Uropathogenic Escherichia Coli (UPEC) cells, widely implicated in food-poisoning outbreaks and urinary tract infections respectively. Cells tethered to a surface are tracked on the nanometer scale, and phenotypic motion is correlated with bacterial metabolism. Antibiotic action significantly slows down motion of tethered bacterial cells, which is used to perform antibiotic susceptibility testing. Using this technology, the clinical minimum bactericidal concentration of an antibiotic against UPEC pathogens was calculated within 2 hours directly in urine samples as compared to 3 days using current gold standard tools.
Such technologies can make a tremendous impact to improve the efficacy and efficiency of infectious disease treatment. This has the potential to reduce the antibiotic mis-prescription steeply, which can drastically decrease the annual 2M+ hospitalizations and 23,000+ deaths caused due to antibiotic resistance bacteria along with saving billions of dollars to payers, patients, and hospitals.
In this dissertation, I developed a nonculture-based AST using an imaging and cell tracking technology. I track individual Escherichia coli O157:H7 (E. coli O157:H7) Uropathogenic Escherichia Coli (UPEC) cells, widely implicated in food-poisoning outbreaks and urinary tract infections respectively. Cells tethered to a surface are tracked on the nanometer scale, and phenotypic motion is correlated with bacterial metabolism. Antibiotic action significantly slows down motion of tethered bacterial cells, which is used to perform antibiotic susceptibility testing. Using this technology, the clinical minimum bactericidal concentration of an antibiotic against UPEC pathogens was calculated within 2 hours directly in urine samples as compared to 3 days using current gold standard tools.
Such technologies can make a tremendous impact to improve the efficacy and efficiency of infectious disease treatment. This has the potential to reduce the antibiotic mis-prescription steeply, which can drastically decrease the annual 2M+ hospitalizations and 23,000+ deaths caused due to antibiotic resistance bacteria along with saving billions of dollars to payers, patients, and hospitals.
ContributorsSyal, Karan (Author) / Tao, Nongjian (Thesis advisor) / Haydel, Shelley (Committee member) / Rege, Kaushal (Committee member) / Wang, Shaopeng (Committee member) / Haynes, Karmella (Committee member) / Arizona State University (Publisher)
Created2017
Description
Cytometry is a method used to measure and collect the physical and chemical characteristics of a population of cells. In modern medical settings, the trend of precision and personalized medicines has imposed a need for rapid point-of-care diagnostic technologies. A rapid cytometric method, which aims at detecting and analyzing cells in direct patient samples, is therefore desirable. This dissertation presents the development of light-scattering-based imaging methods for detecting and analyzing cells and applies the technology in four applications. The first application is tracking phenotypic features of single particles, thereby differentiating bacterial cells from non-living particles in a label-free manner. The second application is a culture-free antimicrobial susceptibility test that rapidly tracks multiple, antimicrobial-induced phenotypic changes of bacterial cells with results obtained within 30 – 90 minutes. The third application is rapid antimicrobial susceptibility testing (AST) of bacterial cell growth directly in-patient urine samples, without a pre-culture step, within 90 min. This technology demonstrated rapid (90 min) detection of Escherichia coli in 24 clinical urine samples with 100% sensitivity and 83% specificity and rapid (90 min) AST in 12 urine samples with 87.5% categorical agreement with two antibiotics, ampicillin and ciprofloxacin. The fourth application is a multi-dimensional imaging cytometry system that integrates multiple light sources from different angles to simultaneously capture time-lapse, forward scattering and side scattering images of blood cells. The system has demonstrated capacity to detect red blood cell agglutination, assess red blood cell lysis, and differentiate red and white blood cells for potential implementation in clinical hematology analyses. These large-volume, light-scattering cytometric technologies can be used and applied in clinical and research settings to study, detect, and analyze cells. These studies developed rapid point-of-care diagnostic and imaging technologies for collectively advancing modern medicine and global health.
ContributorsMo, Manni (Author) / Borges, Chad (Thesis advisor) / Tao (Deceased), Nongjian (Thesis advisor) / Wang, Shaopeng (Committee member) / Chiu, Po-Lin (Committee member) / Haydel, Shelley (Committee member) / Arizona State University (Publisher)
Created2020
Description
Quantifying molecular interactions is pivotal for understanding biological processes at molecular scale and for screening drugs. Although various detection technologies have been developed, it is still challenging to quantify the binding kinetics of small molecules because the sensitivities of the mainstream technologies scale down with the size of the molecule. To address this problem, two different optical detection methods, charge sensitive optical detection (CSOD) and virion
ano-oscillators, are developed to measure the binding-induced charge change instead of the mass change, which enables quantification of the binding kinetics for both large and small molecules.
In particular, the nano-oscillator approach provides a unique capability to image individual nanoparticles and measure the size and charge of each nanoparticle simultaneously. This approach is applied to measure one of the smallest biological particles - single protein molecules. By tracking the oscillation of each protein molecule, the size, charge, and mobility are measured in real-time with high precision. This capability also allows to monitor the conformation and charge changes of single protein molecules upon ligand binding. Measuring the size and charge of single proteins opens a new revenue to protein analysis and disease biomarker detection at the single molecule level.
The virion
ano-oscillators and the single protein approach employ a scheme where a particle is tethered to the surface with a polymer molecule. The dynamics of the particle is governed by two important forces: One is entropic force arising from the conformational change of the molecular tether, and the other is solvent damping on the particle and the molecule. The dynamics is studied by varying the type of the tether molecule, size of the particle, and viscosity of the solvent. The findings provide insights into single molecule studies using not only tethered particles, but also other approaches, including force spectroscopy using atomic force microscopy and nanopores.
ano-oscillators, are developed to measure the binding-induced charge change instead of the mass change, which enables quantification of the binding kinetics for both large and small molecules.
In particular, the nano-oscillator approach provides a unique capability to image individual nanoparticles and measure the size and charge of each nanoparticle simultaneously. This approach is applied to measure one of the smallest biological particles - single protein molecules. By tracking the oscillation of each protein molecule, the size, charge, and mobility are measured in real-time with high precision. This capability also allows to monitor the conformation and charge changes of single protein molecules upon ligand binding. Measuring the size and charge of single proteins opens a new revenue to protein analysis and disease biomarker detection at the single molecule level.
The virion
ano-oscillators and the single protein approach employ a scheme where a particle is tethered to the surface with a polymer molecule. The dynamics of the particle is governed by two important forces: One is entropic force arising from the conformational change of the molecular tether, and the other is solvent damping on the particle and the molecule. The dynamics is studied by varying the type of the tether molecule, size of the particle, and viscosity of the solvent. The findings provide insights into single molecule studies using not only tethered particles, but also other approaches, including force spectroscopy using atomic force microscopy and nanopores.
ContributorsMa, Guangzhong, Ph.D (Author) / Tao, Nongjian (Thesis advisor) / Wang, Shaopeng (Thesis advisor) / Ros, Alexandra (Committee member) / Guo, Jia (Committee member) / Arizona State University (Publisher)
Created2019