• Title:Electrochemical Imaging by Soft Probes
  • Start Date/Time:2019-04-23 / 11:00
  • End Date/Time :2019-04-23 / 12:00
    • Speaker:Prof. Tzu-En Lin (NCTU)
    • Place:Lecture Room A of NCTS, 4F, 3rd General Building, Nat'l Tsing Hua Univ.
    • Host:Prof. Lee-Wei Yang (NTHU)
    • Abstract: Scanning electrochemical microscopy (SECM) is a scanning probe technique that is composed of a micro- or nanoelectrode that can be scanned in close proximity to an interface. Faradaic current signals can be recorded due to the flux of redox active species between the sample and an amperometric SECM probe. SECM can be used to image the topography and reactivity of biological specimens for mapping localized biochemical activity. Although SECM has been applied to different biological systems, SECM studies of tissues are still under exploration. The reason is due to the shape and high roughness of such real samples and requires overcoming major drawbacks in conventional SECM instrumentation when scanning large, i.e. square centimeter sized, areas with irregular surface keeping a constant working distance. My research aims to develop various reliable SECM bioimaging techniques for the study of the antioxidant defense system of fruit peels, distribution of biomarkers and nanomaterials in thin and thick animal samples, as well as human melanoma. Particularly the last is of major importance, because melanoma is the most lethal form of skin cancer striking thousands of people around the world. The survival rate depends on the stage of the cancer when it is diagnosed. Therefore, reliable methodologies for early diagnosis and unequivocal identification of cancer stages are of high relevance. It is demonstrated that SECM could improve the diagnosis and understanding of different melanoma stages based on highly resolved maps of the tyrosinase distribution while being immune against optical interferences, e.g. from the presence of melanin in the skin samples. [1] Spider probe composed of eight independent microelectrodes was developed in this thesis and allowed the large area scanning in contact mode on thin and thick animal tissues. The redox active proteins inside the entire mouse heart were imaged with an SECM system for the first time by spider probe (Fig.1). In addition, the distributions of injected conductive graphene nanoribbons (GONRs) for drug delivery were studied by Soft-Probe-SECM. Through the mapping of feedback mode currents over conductive GONRs, the GONRs were found concentrated inside lobules, which are hexagonal microstructures in the liver. [2] In the future, further functionalization of the soft probes by integrating microfluidics could allow the delivery of anti-cancer drugs at the tip of the probe and the extraction of species locally generated by stimulated living cells for cancer research.

      Figure 1

      Figure 1. Photo of a soft SECM spider probe which is composed of 8 individual microelectrodes.
      [1] T.-E. Lin, A. Bondarenko, A. Lesch, H. Pick, F. Cortés-Salazar, H. H. Girault, Angew. Chem. Int. Ed. 2016, 55, 3813-3816.
      [2] T.-E. Lin, Y.-J. Lu, C.-L. Sun, H. Pick, J. P. Chen, A. Lesch, H. H. Girault, Angew. Chem. Int. Ed. 2017, 56, 16498-16502

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