Dual optical detection of norepinephrine with hydrothermally synthesized nitrogen-doped MXene quantum dots

초록

This study presents an affordable, rapid, and highly sensitive dual mode platform for norepinephrine (NE) detection using ethylenediamine (EDA) doped MXene quantum dots (NMxQDs). The NMxQDs were synthesized through a hydrothermal method, which provides uniformly distributed, well-shaped, and high-quality quantum dots. Notably, earlier reports using microwave assisted NMxQDs showed much higher LOD values, further highlighting the advantage of the hydrothermal approach. The prepared NMxQDs enable both colorimetric and fluorescence-based sensing with strong selectivity toward NE. The colorimetric assay shows an enzyme free visual response with a linear range of 20 to 100 & micro;M and LODs of 5.84 & micro;M in acetate buffer and 6.70 & micro;M in human serum. The fluorescence assay offers a broader detection range from 5 nM to 100 & micro;M with LODs of 6.4 nM in PBS and 11.6 nM in serum. All measurements exhibit excellent linearity and strong resistance to interference from coexisting biomolecules. Key sensing parameters were systematically optimized for both detection modes, and the stability and repeatability of the assays were verified. Fluorescence decay analysis indicates that quenching occurs mainly through a static mechanism. Overall, these results demonstrate a reliable and interference tolerant sensing platform for NE monitoring in biological samples.

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