Automated and enhanced extraction of a small molecule-drug conjugate using an enzyme-inhibitor interaction based SPME tool followed by direct analysis by ESI-MS

  • Sahar Ghiasikhou
  • Samuele Cazzamalli
  • Jörg Scheuermann
  • Dario Neri
  • Renato ZenobiEmail author
Paper in Forefront


We report a novel, fast, and automatic SPME-based method capable of extracting a small molecule-drug conjugate (SMDC) from biological matrices. Our method relies on the extraction of the drug conjugate followed by direct elution into an electrospray mass spectrometer (ESI-MS) source for qualitative and quantitative analysis. We designed a tool for extracting the targeting head of a recently synthesized SMDC, which includes acetazolamide (AAZ) as high-affinity ligand specific to carbonic anhydrase IX. Specificity of the extraction was achieved through systematic optimization. The design of the extraction tool is based on noncovalent and reversible interaction between AAZ and CAII that is immobilized on the SPME extraction phase. Using this approach, we showed a 330% rise in extracted AAZ signal intensity compared to a control, which was performed in the absence of CAII. A linear dynamic range from 1.2 to 25 μg/ml was found. The limits of detection (LOD) of extracted AAZ from phosphate-buffered saline (PBS) and human plasma were 0.4 and 1.2 μg/ml, respectively. This with a relative standard deviation of less than 14% (n = 40) covers the therapeutic range.

Graphical abstract


Capillary gap sampler Solid-phase microextraction Targeted drug delivery Small molecule-drug conjugates Carbonic anhydrase Acetazolamide 



We gratefully thank Dr. Christof Fattinger (Roche) for his support in sampler development. Moreover, we thank the Scientific Center for Optical and Electron Microscopy (ScopeM), a central technology platform of ETH Zurich, for providing us with resources and services in electron microscopy. Finally, we thank the Swiss National Science Foundation (SNSF) for funding this project (Grant numbers 200020-159929 & 200020-178765).

Associated content

The original data used in this publication are made available in a curated data archive at ETH Zurich ( under the

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest

Supplementary material

216_2019_2165_MOESM1_ESM.pdf (354 kb)
ESM 1 (PDF 354 kb).


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Sahar Ghiasikhou
    • 1
  • Samuele Cazzamalli
    • 1
  • Jörg Scheuermann
    • 1
  • Dario Neri
    • 1
  • Renato Zenobi
    • 1
    Email author
  1. 1.Department of Chemistry and Applied BiosciencesETH ZurichZurichSwitzerland

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