This study investigates the synthesis and characterization of superparamagnetic iron oxide nanoparticles (SPIONs) coated with cross-linked poly(ethylene glycol)-co-fumarate (PEGF) to enhance their stability and reduce the burst effect. The PEGF coating was synthesized by a modified method, and the resulting nanoparticles were characterized using various techniques such as TEM, SEM, FTIR, 1H NMR, XRD, and VSM. The cross-linked PEGF coating significantly reduced the burst effect of the drug tamoxifen, which was loaded onto the nanoparticles. In vitro biocompatibility tests using L929 and K562 cells showed that the PEGF-coated SPIONs were more biocompatible than those coated with other polymers. The study concludes that the cross-linked PEGF-coated SPIONs are promising for applications in drug delivery and imaging due to their enhanced stability and reduced burst effect.This study investigates the synthesis and characterization of superparamagnetic iron oxide nanoparticles (SPIONs) coated with cross-linked poly(ethylene glycol)-co-fumarate (PEGF) to enhance their stability and reduce the burst effect. The PEGF coating was synthesized by a modified method, and the resulting nanoparticles were characterized using various techniques such as TEM, SEM, FTIR, 1H NMR, XRD, and VSM. The cross-linked PEGF coating significantly reduced the burst effect of the drug tamoxifen, which was loaded onto the nanoparticles. In vitro biocompatibility tests using L929 and K562 cells showed that the PEGF-coated SPIONs were more biocompatible than those coated with other polymers. The study concludes that the cross-linked PEGF-coated SPIONs are promising for applications in drug delivery and imaging due to their enhanced stability and reduced burst effect.