MOFs-functionalized regenerable SERS sensor based on electrochemistry for pretreatment-free detection of serum alkaline phosphatase activity

Alkaline phosphatase (ALP), widely distributing in the human body, associates with many liver and bone diseases. Herein, we designed a reusable surface-enhanced Raman scattering (SERS) sensor via electrochemical self-assembly of Au nanoparticles (AuNPs) and zinc-based metal organic frameworks (Zn-MOFs) at anodic aluminum oxide (AAO) membrane for detecting ALP activity. The detection is based on the sensitive SERS response of the newly synthesized 2-mercaptoquinone (2-MBQ) modified on AuNPs surface towards ascorbic acid (AA) formed from the dephosphorylation of ascorbic acid 2-phosphate (AA2P) in the presence of ALP. Benefitting from the sieving function of Zn-MOFs and superiority of SERS, the developed sensor exhibited strong anti-interference performance and wide detection range from 1 to 300 U/L with a detection limit of 0.38 U/L, which allowed the direct detection of ALP activity in serum without any pretreatment. Besides, we regenerated the used sensor through the electrochemical oxidation of the reduced probe molecule 2-mercaptohydroquinone (2-MHQ). The regenerated sensor exhibited good maintenance of sensitive response to ALP, in favor of improving the usage efficiency and cutting the test cost. This work provides a promising platform for early diagnosis of ALP-related diseases and paves the way towards developing regenerable and pretreatment-free SERS sensors.