Surface modification is an important part of fabricating nanoparticles with specific properties and functions. We have designed a dipeptide, which we call NS polypeptide, that consists of four asparagine (N) residues and one serine (S) residue, as a molecule for nanoparticle surface modification. Surface modification of magnetic nanoparticles with the NS polypeptide results in reduction of particle-particle and particle-cell interactions. Here, we describe the surface modification and functionalization of bacterial magnetic particles (BacMPs) by spontaneous integration of temporin L conjugated to NS polypeptide. BacMP membranes were modified temporin L. Furthermore, peptide-modified BacMPs showed high dispersibility in aqueous solution compared to unmodified BacMPs. This surface modification technique may represent a new strategy for reducing non-specific binding of nanoparticles to proteins or cells for use in a variety of protein- or cell-associated applications.