Non-invasive detection of gastric cancer relevant d-amino acids with luminescent DNA/silver nanoclusters.

Chirality plays essential roles in life systems such that l-amino acids (LAAs) are predominantly found as the building units of protein for organisms. The presence of the d-enantiomer (DAA) has been found to be specifically relevant to gastric cancer. We herein construct a luminescent DNA/silver nanocluster based biosensing system to achieve rapid and specific detection of DAAs. As a proof of application, we detected DAAs in saliva samples from patients with gastric cancer, and the test results exhibited excellent specificity. Our detection system has the following major advantages: (i) the detection is rapid, being completed in less than 1 hour; (ii) the limit of detection falls in the effective range of DAA concentrations of gastric cancer at an early stage, indicating that our method is potentially suitable for early diagnosis of gastric cancer; (iii) the non-invasive sampling manner provides an adaptable system for point-of-care testing (POCT); and (iv) the system does not require any massive instruments or expensive reagents, which enables POCT as well.