RESUMEN
Fluorescent nanothermometers based on thermal-dependent lifetime have a significant advantage in biological imaging owing to their immunity toward scattering, absorption, and autofluorescence. In this study, we present the first example of a water-soluble europium complex ([L1Eu]-) that exhibits high sensitivity (1.2% K-1 at 298 K) based on a temperature-dependent lifetime in the millisecond time range. This complex and its analogues show considerable potential for organelle imaging. The mechanism behind this thermal-sensitive behavior has been extensively investigated using transient absorption spectroscopy and variable temperature time-resolved luminescence methods. A highly efficient ligand sensitization process and a thermally activated back energy transfer process have been demonstrated. This study bridges the gap in small molecule thermometers with lifetimes longer than 1 ms and provides guidance in ligand design for metal coordination complex thermometers.
RESUMEN
Cyclen-peptide bioconjugates are usually prepared in multiple steps that require individual preparation and purification of the cyclic peptide and hydrophilic cyclen derivatives. An efficient strategy is discovered for peptide cyclization and functionalization toward lanthanide probe via three components intermolecular crosslinking on solid-phase peptide synthesis with high conversion yield. Multifunctionality can be conferred by introducing different modular parts or/and metal ions on the cyclen-embedded cyclopeptide. As a proof-of-concept, a luminescent Eu3+ complex and a Gd3+-based contrasting agent for in vitro optical imaging and in vivo magnetic resonance imaging, respectively, are demonstrated through utilizing this preparation of cyclen-embedded cyclic arginylglycylaspartic acid (RGD) peptide.