Browsing by Subject "Label-free virus detection"
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Item Open Access Atmospheric pressure mass spectrometry of single viruses and nanoparticles by nanoelectromechanical systems(American Chemical Society, 2022-01-04) Erdogan, R. Tufan; Alkhaled, Mohammed; Kaynak, Batuhan E.; Alhmoud, Hashim; Pisheh, Hadi Sedaghat; Kelleci, Mehmet; Karakurt, Ilbey; Yanik, C.; Şen, Zehra Betül; Sari, B.; Yagci, A. M.; Özkul, A.; Hanay, M. SelimMass spectrometry of intact nanoparticles and viruses can serve as a potent characterization tool for material science and biophysics. Inaccessible by widespread commercial techniques, the mass of single nanoparticles and viruses (>10MDa) can be readily measured by nanoelectromechanical systems (NEMS)-based mass spectrometry, where charged and isolated analyte particles are generated by electrospray ionization (ESI) in air and transported onto the NEMS resonator for capture and detection. However, the applicability of NEMS as a practical solution is hindered by their miniscule surface area, which results in poor limit-of-detection and low capture efficiency values. Another hindrance is the necessity to house the NEMS inside complex vacuum systems, which is required in part to focus analytes toward the miniscule detection surface of the NEMS. Here, we overcome both limitations by integrating an ion lens onto the NEMS chip. The ion lens is composed of a polymer layer, which charges up by receiving part of the ions incoming from the ESI tip and consequently starts to focus the analytes toward an open window aligned with the active area of the NEMS electrostatically. With this integrated system, we have detected the mass of gold and polystyrene nanoparticles under ambient conditions and with two orders-of-magnitude improvement in capture efficiency compared to the state-of-the-art. We then applied this technology to obtain the mass spectrum of SARS-CoV-2 and BoHV-1 virions. With the increase in analytical throughput, the simplicity of the overall setup, and the operation capability under ambient conditions, the technique demonstrates that NEMS mass spectrometry can be deployed for mass detection of engineered nanoparticles and biological samples efficiently.Item Embargo Nanomechanical and microwave resonance sensing for characterization of individual virions and nanoparticles in atmospheric conditions(Bilkent University, 2023-09) Alkhaled, MohammedThis dissertation focuses on Nanoelectromechanical-based Mass Spectrometry (NEMS-MS), an innovative technique for characterizing nanoparticles and biomolecules weighing above the working limit of commercial mass spectrometry tools. It suggests performing NEMS-MS under atmospheric conditions and enhancing its capabilities with a built-in focusing lens. Amid the COVID-19 pandemic, the study addresses urgent virus detection needs, proposing a label-free method using NEMS-MS for individual virus detection and characterization. Notably, the study achieves mass spectrometry measurement of the SARS-CoV-2 virus using a NEMS-MS system operating entirely under atmospheric pressure. As the first to pioneer NEMS-MS in air, the study examines challenges tied to this, particularly how NEMS response in dissipative environments, known as Mode Shape Attenuation. Mathematical models and experiments dissect factors contributing to this attenuation, resulting in improved mass spectra and contributing toward the utilization of NEMS-MS for real-world application. Taking innovation a step further, the study introduces a microwave-based sensor for inferring electrical properties of nanoparticles. This sensor works in the electro-magnetic domain, determining properties like dielectric constant and expanding the sensing possibilities. Overall, this dissertation propels NEMS-based sensing and characterization by combining mass spectrometry, microwave sensing, and atmospheric pressure operation. Addressing challenges and introducing innovative solutions, it advances NEMS-MS technology and offers a cost-effective tool for characterizing nanoparticles and biomolecules across various applications.