Enzymatically Cyclic Activated Biosensor Based on a Tetrahedral DNA Framework for Precise Tumor in Situ Molecular...

Area of Science:

• Biomedical Engineering
• Molecular Imaging
• Nucleic Acid Nanotechnology

Background:

• Tumor molecular imaging requires strategies with high spatial specificity and sensitivity to overcome challenges like off-tumor signal leakage and low biomarker abundance.
• The enzyme apurinic/apyrimidinic endonuclease 1 (APE1) is a promising target due to its differential expression in cancer cells (cytosolic and nuclear) compared to normal cells (predominantly nuclear).

Purpose of the Study:

• To develop a cyclically activated enzymatic biosensor for tumor cell-specific molecular imaging.
• To utilize the apurinic/apyrimidinic endonuclease 1 (APE1) enzyme's activity for enhanced sensitivity and spatial specificity in detecting tumor cells.

Main Methods:

• A tetrahedral framework nucleic acid (tFNA) modified with an abasic (AP) site (AP-tFNA) was designed as a substrate for APE1.
• The biosensor relies on APE1-induced cleavage of the AP site, separating a fluorophore and quencher to generate a detectable fluorescence signal.
• The cyclic activation mechanism allows for signal amplification upon repeated APE1 recognition and cleavage.

Main Results:

• The AP-tFNA biosensor demonstrated high specificity in differentiating tumor cells from normal cells both in vitro and in vivo.
• The system achieved sensitive detection of tumor cells, correlating with APE1 enzyme activity.
• The biosensor successfully monitored drug resistance in neuroblastoma cells and classified patient risk using plasma samples.

Conclusions:

• The developed AP-tFNA biosensor provides a sensitive and spatially specific platform for tumor molecular imaging.
• This approach holds potential for real-time monitoring of therapeutic responses and clinical risk stratification in cancer patients.
• The cyclically activated enzymatic strategy offers a promising avenue for improving diagnostic capabilities in oncology.