Flexible disulfide-bridged hyperbranched poly(amido amine)s based nonconjugated carbonized polymer dots for iron (III) sensing and its application in meat by-product.

Herein, a novel flexible disulfide-bridged hyperbranched poly(amido amine)s based nonconjugated carbonized polymer dots (ssHPA-CPDs) was developed using citric acid and ssHPA with disulfide bonds as precursors. The structure and composition of ssHPA-CPDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, raman spectroscopy, and small-X-ray scattering. The results show that when the mass ratio of ssHPA-CPDs/citric acid is 0.5, graphite nitrogen and thiophenone/thiazole sulfur occupy a dominant position, with a higher quantum yield (29.08%). The high disulfide bond content increases ssHPA-CPDs flexibility, leading to greater surface roughness and enhanced Fe(III) binding. In addition, the fluorescence intensity of ssHPA-CPDs at 465 nm λex = 350 nm was used as the quantitative signal for Fe(III) detection with a limit of detection of 0.07 μM. The ssHPA-CPDs offering a rapid (1.0 min) and reproducible (three times) method by adding ascorbic acid for accurately determining Fe(III) content in liver and blood samples, with spiked recovery rates ranging from 87.47% to 106.01%. This method adopts flexible disulfide-bridged CPDs to regulate quantum yield, offering a rapid and accurate approach to detect Fe(III) content in meat by-products for the evaluation of food safety and human health.