Incorporating of gold nanoclusters into metal-organic frameworks for highly sensitive detection of 3-nitrotyrosine as an oxidative stress biomarker

3-nitrotyrosine (3NT) level in biological samples, considered as an appropriate biomarker for nitrosative stress, is associated with many inflammatory and chronic diseases. In this research, a novel highly fluorescent hybrid material (AuNCs@ZIF-8) has been synthesized by encapsulating gold nanoclusters (AuNCs) into the zeolitic imidazolate framework (ZIF-8). Due to the confinement-assisted emission enhancement, the quantum yield of AuNCs@ZIF-8 attained to 36.6 %, which was nearly 15 times that of the sole AuNCs. The obtained AuNCs@ZIF-8 composites were used to develop an ultrasensitive and highly selective sensor for 3NT. In comparison with sensing by pure AuNCs without the amplifying effect of ZIF-8, the developed AuNCs@ZIF-8 based sensor indicated almost two orders of magnitude lower limit of detection (LOD), and 3NT could be detected in the range of 5−200 nM with a detection limit of 1.8 nM (S/N = 3). The developed sensor was applied to quantify 3NT in biological samples and satisfactory results were obtained.