Peptide-functionalized metal-organic framework nanocomposite for ultrasensitive detection of secreted protein acidic and rich in cysteine with practical application.

In this work, we have prepared peptide-functionalized metal-organic frameworks (MOFs) as signal-amplifying tags for the detection of secreted protein acidic and rich in cysteine (SPARC). Furthermore, enzyme-MOF nanocomposites are fabricated via a coprecipitation strategy between horse radish peroxidase (HRP) and ZIF-90, where ZIF-90 is used as a protective support for HRP immobilization. Meanwhile, the peptide sequence has been designed as SPARC-binding peptide, which imparts biorecognition functionality to HRP@ZIF-90 for performing a colorimetric sensor. Therefore, during the test, HRP molecules can be quickly released from nanocomposites by acidic condition to catalyze chromogenic reaction, enabling the ultrasensitive detection of SPARC with a low detection limit of 30 fg/mL. Moreover, the content of SPARC in colon cancer tissues with different degrees of differentiation can be determined with this sensor, demonstrating that the expression of SPARC is closely related to the occurrence, invasion and metastasis of human colon cancer. These results may show the potential applications of this biosensor in SPARC fundamental research as well as clinical diagnosis in the future.