XRD patterns and FTIR spectrum

it can be concluded that SPION-CDs has a crystal structure similar to that of Fe3O4 and the core-shell structure of SPION-CDs with different carbon resources was confirmed. The adsorption of aptamer on the surface of SPION-CDs was confirmed according to comparison between FTIR spectrums of SPION-CDs and APT-SPION-CDs.