Ultrathin Self-Assembled Diphenylalanine Nanosheets through a Gold-Stabilized Strategy for High-Efficiency Adsorption/Desorption/Ionization.

Herein, the ultrathin and robust diphenylalanine (FF) self-assembled nanosheets were fabricated by a gold-stabilized strategy for the first time, using a facile electrospray method followed by a thermal treatment process. The key for the gold-stabilized mechanism was explored, demonstrating that the synergy of the stable binding and steric effect between gold nanoparticles (AuNPs) and the exposed amino groups of FF nanosheets, led to strong thermal stability and solvent resistance of the composites. Contributing to the features of remarkable accessible surfaces and strong laser light absorption ability of this FF/Au nanosheets, two robust functional devices, that is, solid-phase microextraction (SPME) fiber and surface-assisted laser desorption/ionization (SALDI) platforms, were in situ prepared for in vitro and in vivo biological analysis. The findings indicated that the fabricated platforms possessed two advantages: (1) rapid absorption/desorption speed (within 5 min) and (2) remarkable enhancement of ionization efficiency with 2 orders of magnitude. As a result, the extraction efficiency of the SPME fiber and the quantitation ability of SALDI platform were significantly improved. This study not only demonstrated that FF/Au composites could be prepared through an electrospray method followed with thermal-treatment to serve as promising adsorption/desorption/ionization materials for specific applications but also provided useful strategy to advance the ideas for future combination of SPME with LDI technique.