Triboelectric Nanogenerators (TENG) for Cultural Heritage
What the big deal about sample size?
Sampling objects of cultural heritage (CH) requires a balance between acquiring enough sample to perform the required analysis, but also minimizing the volume of material removed to prevent visible loss or the rapid consumption of irreplaceable artworks. While mass spectrometry (MS) techniques are sensitive for the low-sample quantities obtained, the destructive nature of the technique can make it undesirable for structural analysis. Additionally the targeted analysis of proteins can be challenging by MS alone without front-end separation that is often sample-expensive (i.e. large sample sizes are taken from the artwork) and may not be amenable for the limited sample extracted from CH objects. By using Triboelectric Nanogenerators (TENG) hyphenated with ion mobility-mass spectrometry (IM-MS) techniques we aim to both minimize the amount of sample needed for a traditional MS method as well as increase the information content obtained for proteinaceous materials extracted from objects.
TENG-IM-MS setup and expected outcomes. (A) Conductive TENG emitter using a copper sleeve for indirect (inductive) voltage application and whether such devices produce native (blue) or unfolded (red) protein structures. (B) Predicted charge states of native CH proteins. (C) Predicted CCS of native CH proteins. Green line indicates expected trend for non-native or supercharged protein structures. Reference protein values acquired from the Collision Cross Section Database from the Bush lab at the University of Washington.
What are triboelectric nanogenerators?
Triboelectric Nanogenerator (TENG) electrospray ionization sources, first described as mechanical generators for microelectronics1, have been shown to have excellent MS applications providing sensitivity and reproducible measurements for several molecular classes2,3. By taking two triboelectric materials and either putting them in contact, or sliding them, with one another mechanical energy can be converted to electricity, and this electric current can be redirected using a circuit to an ion source. Recently, these devices have also been shown to be able to generate protein ions that would be consistent with native structures4, and with precise tuning to be capable of synchronous data acquisition with time dispersive instruments to maximize sample limited analytes5.
Such TENG devices are advantageous because they are simple devices that works by placing two triboelectric materials into contact to generate triboelectricity that can be used to power the ion source that generates ions for an MS instrument. These devices have also been shown to be capable of generating sufficient signal with picoliter volume quantities and sub-micromolar concentrations of sample2,5. When combined with other state-of-the-art instrumentation and methodologies (e.g top-down, native, ion mobility, etc.), TENG is potentially transformative for the characterization of cultural heritage materials by minimizing the amount of material extracted and provide structure and stability information content currently unobtainable with existing technologies.
(A) Sub-microliter sample volume injected in emitter. (B) Emitter is housed in front of mass spectrometer sampling cone. (C) Pulsed ion signal can modulated to match time-dispersive instruments maximizing duty cycle.
(1) Wang, Z. L. Triboelectric Nanogenerators as New Energy Technology and Self-Powered Sensors – Principles, Problems and Perspectives. Faraday Discuss. 2014, 176 (11), 447–458.
(2) Li, A.; Zi, Y.; Guo, H.; Wang, Z. L.; Fernández, F. M. Triboelectric Nanogenerators for Sensitive Nano-Coulomb Molecular Mass Spectrometry. Nat. Nanotechnol. 2017, 12 (5), 481–487.
(3) Bernier, M. C.; Li, A.; Winalski, L.; Zi, Y.; Li, Y.; Caillet, C.; Newton, P.; Wang, Z. L.; Fernández, F. M. Triboelectric Nanogenerator (TENG) Mass Spectrometry of Falsified Antimalarials. Rapid Commun. Mass Spectrom. 2018, 32 (18), 1585–1590.
(4) Bouza, M.; Li, Y.; Wu, C.; Guo, H.; Wang, Z. L.; Fernández, F. M. Large-Area Triboelectric Nanogenerator Mass Spectrometry: Expanded Coverage, Double-Bond Pinpointing, and Supercharging. J. Am. Soc. Mass Spectrom. 2020, 31 (3), 727–734.
(5) Li, Y.; Bouza, M.; Wu, C.; Guo, H.; Huang, D.; Doron, G.; Temenoff, J. S.; Stecenko, A. A.; Wang, Z. L.; Fernández, F. M. Sub-Nanoliter Metabolomics via Mass Spectrometry to Characterize Volume-Limited Samples. Nat. Commun. 2020, 11 (1), 1–16.
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This page is based upon work supported by the National Science Foundation Mathematical and Physical Sciences divisions ASCEND program under award number CHE-2138107.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.