Charge calibration standard for atomic force microscope tips in liquids

dc.contributor.authorZypman, Fredy
dc.contributor.authorLi, Li
dc.contributor.authorSteinmetz, Nicole F.
dc.contributor.authorEppell, Steven J.
dc.contributor.orcid0000-0002-2033-3772en_US
dc.date.accessioned2024-03-11T22:05:07Z
dc.date.available2024-03-11T22:05:07Z
dc.date.issued2020-11-17
dc.descriptionResearch articleen_US
dc.description.abstractAn electric charge standard with nanoscale resolution is created using the known charge distribution of a single tobacco mosaic virus coat protein combined with the known packing of these proteins in the virus capsid. This advances the ability to measure charge on nanometric samples. Experimental atomic force microscope (AFM) force-distance curves are collected under aqueous conditions with controlled pH and ion concentration. A mathematical model that considers a polarizable dielectric tip immersed in an electrolyte is used to obtain charge density from the AFM measurements. Interactions between the tip and the sample are modeled using theory that includes monopolar electrostatic interactions, dipolar interactions, screening from both the dielectric nature of ambient water and solvated ions as described by the linear Poisson-Boltzmann equation, and hard-core repulsion. It is found that the tip charge density changes on a timescale of hours requiring recalibration of the tip for experiments lasting more than an hour. As an example of how a charge-calibrated tip may be used, the surface charge densities on 20 individual carboxylate-modified polystyrene (PS) beads are measured. The average of these AFM-measured bead charge densities is compared with the value obtained from conventional titration combined with electron microscopy. The two values are found to agree within 20%. While the comparison demonstrates similarity of the two charge measurements, hypotheses are put forward as to why the two techniques might be expected not to provide identical mean charge densities. The considerations used to build these hypotheses thus underscore the relevance of the method performed here if charge information is required on individual nanoparticles.en_US
dc.identifier.citationLi, L., Steinmetz, N.F., Eppell, S.J., & Zypman, F.R. (2020, November 17) Charge calibration standard for atomic force microscope tips in liquids. Langmuir, 36(45), 13621-13632.en_US
dc.identifier.doihttps://doi.org/10.1021/acs.langmuir.0c02455en_US
dc.identifier.issn07437463
dc.identifier.urihttps://hdl.handle.net/20.500.12202/9945
dc.language.isoen_USen_US
dc.relation.ispartofseriesLangmuir;36(45)
dc.rightsAttribution-NonCommercial-NoDerivs 3.0 United States*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/us/*
dc.subjectelectric charge standarden_US
dc.subjectnanoscaleen_US
dc.subjectatomic force microscope (AFM)en_US
dc.subjectelectron microscopyen_US
dc.titleCharge calibration standard for atomic force microscope tips in liquidsen_US
dc.typeArticleen_US
local.yu.facultypagehttps://www.yu.edu/faculty/pages/zypman-fredyen_US

Files