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

Abstract Convenient and rapid detection of Cu2+ in serum has important clinical significance for related diseases. Herein, a ratiometric detection of Cu2+ 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 Cu2+ has been discovered, the enhancement mechanism is mainly due to the significant increasing generation of Cu2+-induced hydroxyl radical after addition of SPGH. The chemiluminescence (CL) of the luminol-H2O2 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 Cu2+ 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 Cu2+ in serum based on SPGH-assisted enhanced CRET provides a promising potential alternative method for Cu2+ detection in clinical application.