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Zhang, Anqi

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Zhang

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Anqi

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Zhang, Anqi
Author's Publications: search.filters.isAuthorOfPublication.2292b60f-cb1e-47ae-be74-4ee8d9a448de

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    Specific detection of biomolecules in physiological solutions using graphene transistor biosensors
    (Proceedings of the National Academy of Sciences, 2016) Gao, Ning; Gao, Teng; Yang, Xiao; Dai, Xiaochuan; Zhou, W.; Zhang, Anqi; Lieber, Charles
    Nanomaterial-based field-effect transistor (FET) sensors are capable of label-free real-time chemical and biological detection with high sensitivity and spatial resolution, although direct measurements in high–ionic-strength physiological solutions remain challenging due to the Debye screening effect. Recently, we demonstrated a general strategy to overcome this challenge by incorporating a biomolecule-permeable polymer layer on the surface of silicon nanowire FET sensors. The permeable polymer layer can increase the effective screening length immediately adjacent to the device surface and thereby enable real-time detection of biomolecules in high–ionic-strength solutions. Here, we describe studies demonstrating both the generality of this concept and application to specific protein detection using graphene FET sensors. Concentration-dependent measurements made with polyethylene glycol (PEG)-modified graphene devices exhibited real-time reversible detection of prostate specific antigen (PSA) from 1 to 1,000 nM in 100 mM phosphate buffer. In addition, comodification of graphene devices with PEG and DNA aptamers yielded specific irreversible binding and detection of PSA in pH 7.4 1x PBS solutions, whereas control experiments with proteins that do not bind to the aptamer showed smaller reversible signals. In addition, the active aptamer receptor of the modified graphene devices could be regenerated to yield multiuse selective PSA sensing under physiological conditions. The current work presents an important concept toward the application of nanomaterial-based FET sensors for biochemical sensing in physiological environments and thus could lead to powerful tools for basic research and healthcare.
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    Scalable Ultrasmall Three-Dimensional Nanowire Transistor Probes for Intracellular Recording
    (Springer Science and Business Media LLC, 2019-07-01) Zhao, Yunlong; You, Siheng Sean; Zhang, Anqi; Lee, Jae-Hyun; Huang, Jinlin; Lieber, Charles
    New tools for intracellular electrophysiology that push the limits of spatiotemporal resolution while reducing invasiveness could provide a deeper understanding of electrogenic cells and their networks in tissues and push progress towards human-machine interfaces. While significant advances have been made in developing nanodevices for intracellular probes, current approaches exhibit a tradeoff between device scalability and recording amplitude. We address this challenge by combining deterministic shape-controlled nanowire transfer with spatially-defined semiconductor-to-metal transformation to realize scalable nanowire field-effect transistor probe arrays with controllable tip geometry and sensor size, which enable recording of up to 100 mV intracellular action potentials from primary neurons. Systematic studies on neurons and cardiomyocytes show that controlling device curvature and sensor size is critical for achieving high amplitude intracellular recordings. In addition, this device design allows for multiplexed recording from single cells and cell networks and could enable future investigations of dynamics in the brain and other tissues.