Magnetic UiO-66-NO₂ Nanocomposite for Highly Efficient Adsorption and Detection of Sugar Phosphates in Biological Samples

Enrichment and quantification of sugar phosphates (SPx) in biological samples are of great significance in biological medicine. In this work, a magnetic nanoscale metal–organic framework composite, Fe3O4@UiO-66-NO2, was synthesized and utilized as a high-capacity adsorbent for the enrichment of SPx in biological samples. Fe3O4@UiO-66-NO2 exhibited a high specific surface area (310.02 m2/g), a suitable pore size (3.47 nm), and strong magnetism (14.99 emu/g), enabling convenient separation and recovery. Experimental results demonstrated that Fe3O4@UiO-66-NO2 exhibited excellent adsorption performance for five types of SPx, achieving complete adsorption within 6 min at a dosage of 200 μg, and the adsorption process exhibited pH tolerance. The adsorption isotherm result indicated that the maximum adsorption capacities for different SPx ranged from 234.06 mg/g to 403.24 mg/g. Adsorption mechanisms using X-ray photoelectron spectroscopy, FT-IR, and density functional theory revealed multiple interactions, such as coordination and hydrogen bonding, and contributed to the adsorption process. A magnetic nanoscale-dispersive solid-phase extraction protocol was developed based on a Fe3O4@UiO-66-NO2 for rapidly enriching SPx from biological samples. The protocol allowed for SPx detection over a wide linear concentration range, low limits of detection (0.001–0.02 ng/mL), high precision (<7.88%), and good accuracy (82.56%–119.66%). This protocol was successfully applied to real blood samples, prefiguring the great potential of magnetic MOFs for the enrichment and detection of SPx in biological samples.