The various embodiments herein provide super paramagnetic iron oxide nanoparticles (SPIONs). The SPIONs have a plurality of metallic coatings and plurality of polymeric gaps. The embodiments herein also provide a method of synthesizing the SPIONs with metallic rings and polymeric gaps. The metallic coatings form a ring like structure on the outer surface of the SPION. The SPION has a size of 13 nm. The ring has a thickness of 2-3 nm. The rings are one or more in number. The polymeric gaps have a thickness of 3-5 nm. The polymeric gaps are one or more in number. The method involves mixing the SPIONs with a plurality of polymers and then forming a metallic ring on the outer surface of the SPIONs. The SPIONs have anti-bacterial properties and stop a growth of bacterial biofilms. The SPIONs also have SERS properties.