Strategic enhancement of collagen detection using lanthanide-functionalized collagen targeted peptides

Monitoring collagen denaturation is crucial for diagnosing collagen-related diseases such as tumors and fibrosis. Herein, we have developed specific probes to detect denatured collagen (d-Col) and collagen I (Col I), utilizing peptide probes with sequences (GOP)₁₀ and HVWMQAP, targeting at d-Col and Col I, respectively. These peptides were conjugated with 1,10-phenanthroline-5-carboxylic Acid (Phen), forming Phen-Ahx-(GOP)₁₀ and Phen-Ahx-HVWMQAP. Phen acts as both an antenna sensitizer and a chelator, coordinating with Terbium (III) and Europium (III) ions via its nitrogen atom, facilitating fluorescent emission in green and red, respectively. The investigation demonstrated that Tb³⁺ interacts with three (GOP)₁₀ peptide units through Phen, while Eu³⁺ connects with four units of Ahx-HVWMQAP peptides. Additionally, it is important to note that the structure of the peptides remains unchanged after chelating with the lanthanide ions, maintaining their integrity throughout the process. These probes have effectively demonstrated their ability to bind to specific collagen types with selectivity, enabling accurate identification of their presence. The excellent binding of these probes is due to the branched structure of the formed lanthanide-peptide complexes. A dose-dependent linear association was observed in the binding of Eu-[Phen-Ahx-HVWMQAP]₄ to Col I, with concentration levels ranging from 0.5 to 100 μM and a minimal detectable concentration of 0.113 μM. We anticipate that our developed probes will improve understanding of collagen remodeling and provide opportunities for the diagnosis of collagen-associated diseases.