Functionalized graphene oxide in situ initiated ring-opening polymerization for highly sensitive sensing of cytokeratin-19 fragment

Improving the sensitivity of detection is crucial to monitor biomarker, assess toxicity, and track therapeutic agent. Herein, a sensitivity-improved immunosensor is reported for the first time via functionalized graphene oxide (GO) and a grafting-to ring-opening polymerization (ROP) dual signal amplification strategy. Through the ROP reaction using 2-[(4-ferrocenylbutoxy)methyl] oxirane (FcEpo) as the monomer, lots of electroactive tags are linked in situ from multiple initiation sites on the GO surface modified with ethanol amine (GO-ETA), thereby achieving high sensitivity even in the case of trace amounts of tumor markers. The utmost important factor for achieving this high sensitivity is to select functionalized GO as the initiator that contains a large number of repeated hydroxyl functional groups so as to trigger additional ROP reaction. Under the optimal conditions, the high sensitivity and applicability is demonstrated by the use of GO-ETA-mediated ROP-based immunosensor to detect non-small cell lung cancer (NSCLC)-specific biomarker down to 72.58 ag/mL (equivalent to similar to 6 molecules in a 5 mu L sample). Furthermore, the satisfactory results for the determination of biomarkers in clinical serum samples highlighted that this immunosensor holds a huge potential in practical clinical application.

Automated summary

This study introduced a sensitivity-improved immunosensor using functionalized graphene oxide and ring-opening polymerization strategy, demonstrating high sensitivity and applicability for detecting non-small cell lung cancer-specific biomarkers. Satisfactory results in clinical serum samples suggest the enormous potential of this immunosensor in practical clinical application.