The Preparation Of Electrochemiluminescence Composite Materials And Applications In The Detection Of BACE1 Activity

The gradual formation of extracellular senile plaques by β-amyloid(Aβ)aggregation is one of the pathological features of Alzheimer’s disease(AD).Cleavage of amyloid precursor protein by β-amyloid precursor protein cleavage enzyme 1(BACE1)is the ratelimiting step in the Aβ production pathway;therefore,BACE1 is considered as a promising therapeutic target in the early stage of AD.Based on nanofunctional materials and electrochemiluminescence technology,a series of works were carried out for the detection of BACE1 and the screening of its inhibitors.Firstly,luminol-functionalized silver nanoparticle aggregates were synthesized and the BACE1 activity was detected by electrochemiluminescence and electrochemical dual mode based on this composite.Since cucurbit[8]urea(CB[8])can accommodate two aromatic residues simultaneously,the aggregation of peptide 2(P2:FGDDPPPPC)with luminol-functionalized silver nanoparticles was induced,and the obtained(CB[8]-P2AgNPs-luminol)n aggregates with ECL and electrochemical activity were used as dualmode signal probes.The adamantane-functionalized peptide(P1)is assembled by hostguest interaction onto the surface of a glassy carbon electrode electropolymerized with βcyclodextrin.The bimodal signal probe can be captured at the N end of P1 by CB[8],and once the substrate P1 is cleaved by BACE1,the probe-bound peptide fragment is dislodged from the electrode surface,resulting in a significant decrease in ECL and electrochemical signal.Using the signal amplification function of the signal probe,a sensitive dual-mode detection of BACE1 activity can be achieved,with detection limits as low as 33.11 pM in ECL mode and 53.19 pM in electrochemical mode.In order to further improve its operational stability and detection sensitivity,3,4,9,10-pyrenyltetracarboxylic acid(PTCA)-functionalized metal-organic frameworks NH2-Uio-66 and CuO-CeO2-AuNPs were synthesized and based on this material for ECL detection of BACE1 activity.The ECL-active NH2-Uio-66-PTCA-2PCAI composite was used as a signal probe by amidating the large surface area metal-organic framework as a carrier for PTCA and coupling it with the "N"-terminal fixed-point biocoupling reagent 2-pyridinecarboxaldehyde intermediate(2PCAI).The CuO-CeO2-AuNPs acted as a coreaction accelerator to realize the multi-channel catalysis of S2O82-on the one hand,and as a biosensing platform to attach the designed substrate peptides to the modified electrodes via Au-S bonds on the other hand.Once the substrate peptide is cleaved by BACE1,the exposed "N" terminus can capture the signal probe,resulting in an ECL signal.Using the signal amplification function of the signal probe and the high catalytic performance of the heterojunction,the developed biosensor has good sensitivity,wide linear range(20 pM-1 nM)and low detection limit(11.84 pM),and the superior analytical performance of this novel ECL sensor for BACE1 activity suggests that this sensor has promising applications in the early diagnosis of AD.