A specific short peptide-assisted enhanced chemiluminescence resonance energy transfer (CRET) for label-free and ratiometric detection of copper ions in complex samples

Convenient and rapid detection of Cu 2+ in serum has important clinical significance for related diseases. Herein, a ratiometric detection of Cu 2+ based on specific short peptide ( SPGH )-assisted enhanced chemiluminescence resonance energy transfer (CRET) has been constructed. An interesting phenomenon that tetra-peptide with the sequence of Ser-Pro-Gly-His ( SPGH ) was able to specifically and remarkably enhance the catalytic performance of Cu 2+ has been discovered, the enhancement mechanism is mainly due to the significant increasing generation of Cu 2+ -induced hydroxyl radical after addition of SPGH . The chemiluminescence (CL) of the luminol-H 2 O 2 system was efficiently catalyzed by the formed Cu( SPGH ) 2 complex, which acts as an internal light source to triggers on the fluorescence of QDs via CRET, allowing the ratiometric detection of Cu 2+ within 15 min with improved selectivity and sensitivity. The relative standard deviation was lower than 6.38 % due to the ratiometric signal improving its anti-interference ability. Importantly, it is feasible to detect total Cu in human serum, and the results were consistent with that of ICP-AES ( r = 0.9321, n=55). The reliable, rapid, yet simple ratiometric detection of Cu 2+ in serum based on SPGH -assisted enhanced CRET provides a promising potential alternative method for Cu 2+ detection in clinical application.