"On-Off" Sers Sensor Triggered By Ido For Non-Interference And Ultrasensitive Quantitative Detection Of Ido

As a hitman of human health, colon cancer has become the third most common cancer in the world in the recent years. Indoleamine-2,3-dioxygenase (IDO) was found to be closely related to colon cancer. Herein, an "on-off" SERS sensor triggered by enzyme was developed for detecting IDO for presence or absence of colon cancer based on SERS, which composed of Au@MBN@Ag NPs functionalized by aptamer, Tryptophan (Trp) and carboxylated magnetic beads (MNP-COOH). Thus, Au@MBN@Ag NPs were separate from MNP-COOH with the assistance of IDO that catalyzed tryptophan to Kyn, leading to the reduction of SERS intensity of MBN as the increase of the concentration of IDO. Through the method performed within 60 min, the volue of the limit of detection (LOD) is lower to 0.278 ng/mL for IDO ranged from 3.125 ng/mL to 625 ng/mL can be achieved. Additionally, the results of controlled experiment demonstrated that the enzyme-triggered switchable nanoprobes have high specificity for the detection of IDO. Meanwhile, the feasibility of the proposed method in macrophages and clinical serum were also confirmed.