Structures of cobalt stearate as a metal-affinity sorbent for sample preparation in laser desorption/ionization mass spectrometry

The aim of this work was to develop, characterize and apply in a laboratory-on-plate format a new metal-affinity sorbent based on cobalt (II) stearate thin monolayers (films) — FCo. FCo were prepared by the classical Langmuir method and then collapsed. A bath with movable barriers was filled with an aqueous solution of CoCl₂. A solution of stearic acid in hexane was dropwise applied to the surface of the aqueous subphase. The solution spread over the surface, forming a film (layer). After evaporation of hexane from the aqueous subphase, a monolayer of cobalt (II) stearate was formed on the surface, which was slowly compressed by movable barriers. The following parameters were determined for FCo prepared by the classical Langmuir method and then collapsed: specific mass (0.022 ± 0.003 mg/dm²), specific surface area (22.0 ± 2.1 m²/g), isoelectric point value (3.7 pH), moisture content (63 ± 2%), structures ([Co(C₁₇H₃₅COO)₂]H⁺), chemical stability (stable in standard aqueous eluents and in polar organic solvents used in metal-affinity chromatography). Adsorption isotherm of the diclofenac from aqueous solution on FCo was investigated in spin columns (batch). The FCo structure can be obtained on the surface of a subphase drop deposited on a MALDI target plate. Thus the sorbent is formed directly on the surface, preserving the structure and metal-affinity properties. The technique is characterized by cost-effectiveness, simplicity and reproducibility. FCo formed on spot of MALDI target plate provide a high level of sensitivity, specificity and selectivity of the analysis, it is shown that HHb adducts with chlorine-containing alkylating agent can be determined at 0.5% protein modification. Thus, a comprehensive approach for the enrichment of chlorine-containing HHb adducts using a cobalt (II) stearate monolayers on MALDI target plate has been developed.

1. Riguero V., Clifford R., Dawley M., et al. Immobilized metal affinity chromatography optimization for poly-histidine tagged proteins / J. Chromatogr. A. 2020. Vol. 1629. 461505. DOI: 10.1016/j.chroma.2020.461505

2. Kinna A., Tolner B., Rota E. M., et al. IMAC capture of recombinant protein from unclarified mammalian cell feed streams / Biotechnol. Bioeng. 2016. Vol. 113. N 1. P. 130 – 140. DOI: 10.1002/bit.25705

3. Preston G. W., Phillips D. H. Protein Adductomics: Analytical Developments and Applications in Human Biomonitoring / Toxics. 2019. Vol. 7. N 2. 29. DOI: 10.3390/toxics7020029

4. Lockridge O. Overview of Adductomics in Toxicology / Current Protocols. 2023. Vol. 3. N 2. 672. DOI: 10.1002/cpz1.672

5. Marsillach J., Costa L. G., Furlong C. E. Protein adducts as biomarkers of exposure to organophosphorus compounds / Toxicology. 2013. Vol. 307. P. 46 – 54. DOI: 10.1016/j.tox.2012.12.007

6. Bolognesi G., Bacalini M. G., Pirazzini C., et al. Evolutionary Implications of Environmental Toxicant Exposure / Biomedicines. 2022. Vol. 10. N 12. 3090. DOI: 10.3390/biomedicines10123090

7. Amelin V. G., Bolshakov D. S. Rapid screening and determination of neonicotinoid insecticides in water using ultra-high-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry of high resolution / Industr. Lab. Mater. Diagn. 2017. Vol. 83. N 10. P. 18 – 22 [in Russian]. DOI: 10.26896/1028-6861-2017-83-10-18-22

8. Skinner M. K., Manikkam M., Tracey R., et al. Ancestral dichlorodiphenyltrichloroethane (DDT) exposure promotes epigenetic transgenerational inheritance of obesity / BMC Medicine. 2013. Vol. 11. N 1. 228. DOI: 10.1186/1741-7015-11-228

9. Urban P. L., Amantonico A., Zenobi R. Lab-on-a-plate: extending the functionality of MALDI-MS and LDI-MS targets / Mass Spectrom. Rev. 2011. Vol. 30. N 3. P. 435 – 478. DOI: 10.1002/mas.20288

10. Muthu M., Chun S., Wu H. F., et al. The ongoing evolution of laser desorption/ionization mass spectrometry: Some observations on current trends and future directions / J. Mass Spectrom. 2018. Vol. 53. N 6. P. 525 – 540. DOI: 10.1002/jms.4083

11. Shreyner E. V., Alexandrova M. L., Sukhodolov N. G., et al. Extraction of the insecticide dieldrin from water and biological samples by metal affinity chromatography / Mendeleev Commun. 2017. Vol. 27. N 3. P. 304 – 306. DOI: 10.1016/j.mencom.2017.05.030

12. Kurdyukov D. A., Chernova E. N., Russkikh Y. V., et al. Ni-functionalized submicron mesoporous silica particles as a sorbent for metal affinity chromatography / J. Chromatogr. A. 2017. Vol. 1513. P. 140 – 148. DOI: 10.1016/j.chroma.2017.07.043

13. Gladchuk A. S., Silyavka E. S., Shilovskikh V. V., et al. Self-organization of stearic acid salts on the hemispherical surface of the aqueous subphase allows functionalization of matrix-assisted laser desorption/ionization mass spectrometry target plates for on-plate immobilized metal affinity chromatography enrichment / Thin Solid Films. 2022. Vol. 756. 139374. DOI: 10.1016/j.tsf.2022.139374

14. Gorbunov A. Yu., Podolskaya E. P. Fabrication of nanoscale multimolecular structures of lanthanum stearate using Langmuir monolayers for laser desorption/ionization mass spectrometry / Tech. Phys. Lett. 2022. Vol. 48. N 11. P. 29 – 33. DOI: 10.21883/tpl.2022.11.54885.19320

15. Kalninia Y. K., Viskov M. A., Gladchuk A. S., et al. MALDI target functionalization with deposited thin films of lanthanum stearate — An efficient tool for in situ enrichment of human globin adducts of chlorinated organic compounds / Microchem. J. 2024. Vol. 6. N 205. 111300. DOI: 10.1016/j.microc.2024.111300

16. Gladchuk A. S., Gorbunov A. Y., Keltsieva O. A., et al. Coating of a MALDI target with metal oxide nanoparticles by droplet-free electrospraying — A versatile tool for in situ enrichment of human globin adducts of halogen-containing drug metabolites / Microchem. J. 2023. Vol. 191. 108708. DOI: 10.1016/j.microc.2023.108708

17. Babakov V., Gorbunov Ay., Gladchuk A., et al. Identification of phosphonylated peptides using a MALDI target functionalized with lanthanum stearate / Medicine of Extreme Situations. 2023. Vol. 1. N 1. P. 21 – 29. DOI: 10.47183/mes.2023.002

18. Baillie T. A. Drug-protein adducts: past, present, and future / Med. Chem. Res. 2020. Vol. 7. N 29. P. 1093 – 1104. DOI: 10.1007/s00044-020-02567-8

19. Sabbioni G., Day B. W. Quo vadis blood protein adductomics? / Arch. Toxicol. 2022. Vol. 96. N 1. P. 79 – 103. DOI: 10.1007/s00204-021-03165-2

20. Nishikaze T., Takayama M. Cooperative effect of factors governing molecular ion yields in desorption/ionization mass spectrometry / Rapid Commun. Mass Spectrom. 2006. Vol. 20. N 3. P. 376 – 382. DOI: 10.1002/rcm.2316