Target-Combined Enhanced Coordination and Steric Hindrance Enable One-Pot Visual Rapid Quantification of Histone

Histones are critical biomarkers associated with the severity and mortality of sepsis. In this study, a one-pot, highly sensitive dual-mode fluorescence assay for histone detection was developed by leveraging enhanced coordination and steric hindrance effects. Histones can specifically bind to double-stranded DNA (dsDNA), generating complexes with multiple metal ion coordination sites. Therefore, Cu²⁺ was introduced to react with the histone-dsDNA complexes, and the strong steric hindrance produced by the complexes could inhibit reactions between Cu²⁺ and other molecules. Moreover, quantum dots (QDs) selectively recognize dsDNA-Cu²⁺ and histone-dsDNA-Cu²⁺ complexes. Hence, histones were quantitatively analyzed by measuring the fluorescence recovery intensity of QDs. Under optimized conditions, the detection limits of histones were 2.3 fg/mL in the fluorescence mode and 3.8 fg/mL in the red, green, and blue (RGB) mode. A total of 56 clinical serum samples were analyzed; the areas under the curve for discriminating infectious diseases and sepsis were 0.978 and 0.934, respectively. This study developed a sensitive and accurate histone detection assay for patients with clinical infections, demonstrating promising potential for the stratification of infectious diseases and the early auxiliary diagnosis of sepsis.