New Immunosensing-Fluorescence Detection of Tumor Marker Cytokeratin-19 Fragment (CYFRA 21-1) Via Carbon Quantum Dots/Zinc Oxide Nanocomposite

Table 1 A comparative study between the suggested immobilized CQDs/ZnO-BM 19.21 nanocomposite fluorescence immunosensing technique and previously published techniques

Technique	Principle	Linear concentration range, ng mL⁻¹	Lower limit of detection, ng mL⁻¹	References
Enzyme immunoassay	Enzyme immunoassay method using Boehringer Mannheim (Enzymun-Test CYFRA 21-1) in the serum	3.2–11.5	3.5	[5]
Electro-chemiluminescence immunoassay	The ability of an electrochemically luminescent molecule, a tris(2,2′-bipyridyl) ruthenium (II) complex, to be repeatedly excited by tripropylamine	3.1–10.7	3.0	[6]
Suggested immobilized CQDs/ZnO-BM 19.21 nanocomposite immunosensing system	A sandwich capping antibody-antigen-antibody fluorescence immunosensing system of immobilized CQDs/ZnO-BM 19.21	0.01–100	0.008	Present study