title: Dielectrophoresis-Mediated Electrodeformation as a Means of Determining Individual Platelet Stiffness.
abstract: Platelets, essential for hemostasis, are easily activated via biochemical and mechanical stimuli. Cell stiffness is a vital parameter modulating the mechano-transduction of exogenous mechanical stimuli. While methods exist to measure cell stiffness, no ready method exists for measuring platelet stiffness that is both minimally-contacting, imparting minimal exogenous force and non-activating. We developed a minimal-contact methodology capable of trapping and measuring the stiffness of individual platelets utilizing dielectrophoresis (DEP)-mediated electrodeformation. Parametric studies demonstrate a non-uniform electric field in the MHz frequency range (0.2-20 MHz) is required for generating effective DEP forces on platelets, suspended in isotonic buffer with conductivity ~100-200 μS/cm. A nano-Newton DEP force (0.125-4.5 nN) was demonstrated to be essential for platelet electrodeformation, which could be generated with an electric field with strength of 1.5-9 V/μm. Young's moduli of platelets were calculated using a Maxwell stress tensor model and stress-deformation relationship. Platelet stiffness was determined to be in the range of 3.5 ± 1.4 and 8.5 ± 1.5 kPa for resting and 0.4% paraformaldehyde-treated cells, respectively. The developed methodology fills a gap in approaches of measuring individual platelet stiffness, free of inadvertent platelet activation, which will facilitate further studies of mechanisms involved in mechanically-mediated platelet activation.
authors.affiliation: Departments of Medicine and Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA.|Sarver Heart Center, The University of Arizona, 1501 N Campbell Ave, Tucson, AZ, 85724, USA.
authors.forename: Siu Ling
authors.initials: SL
authors.lastname: Leung
authors.affiliation: Departments of Aerospace and Mechanical Engineering, The University of Arizona, Tucson, AZ, 85721, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Biomedical Engineering, HSC T15-090, Stony Brook University, Stony Brook, NY, 11794-8151, USA.
authors.forename: Danny
authors.initials: D
authors.lastname: Bluestein
authors.affiliation: Departments of Medicine and Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA. chairman.syns@gmail.com.|Sarver Heart Center, The University of Arizona, 1501 N Campbell Ave, Tucson, AZ, 85724, USA. chairman.syns@gmail.com.|Department of Biomedical Engineering, HSC T15-090, Stony Brook University, Stony Brook, NY, 11794-8151, USA. chairman.syns@gmail.com.
authors.forename: Marvin J
authors.identifier: http://orcid.org/0000-0002-7864-6691
authors.initials: MJ
authors.lastname: Slepian
mesh_terms: D001792:Blood Platelets / Q000502:physiology*; D055119:Elastic Modulus; D004586:Electrophoresis / Q000379:methods; D006801:Humans; D008839:Microelectrodes; D008962:Models, Theoretical; D015539:Platelet Activation
keywords: Cell stiffness; Dielectrophoresis; Electrodeformation; Mechanotransduction; Platelets; Young’s modulus