Ericka Rodríguez

You asked how to remove molecules from the surface of nanoparticles. Then you explained that you removed some of the extract molecules. Then they asked how to identify complex molecules on the surface of nanoparticles. Typically, a complex mixture of organic molecules is analyzed using a chromatography mass spectrometer. In your example, complex molecules can be covalently bonded to the surface of metallic nanoparticles. Therefore, this method cannot be identified. Use IR spectroscopy, nuclear magnetic resonance, Raman light scattering, UV-visible spectroscopy.

https://books.google.az/books?id=Y8ifDwAAQBAJ&pg=PA371&lpg=PA371&dq=How+remove+extract+bounded+to+surfaces+of+green+synthesis+nanoparticles?&source=bl&ots=OJY-mgeJr4&sig=ACfU3U2SvSR9SIZnwKPcUx65YtWH06jKLg&hl=ru&sa=X&ved=2ahUKEwiymqKTz5_qAhVQyaQKHVLADUAQ6AEwAHoECAgQAQ#v=onepage&q=How%20remove%20extract%20bounded%20to%20surfaces%20of%20green%20synthesis%20nanoparticles%3F&f=false

Puesto que no conoces que moleculas estan en la superficie, lo conveniente es realizar distintos tratamientos. Lava las particulas con 1 M NaCl, lava las particulas con Tween 20, adiciona una molecula conteniendo un grupo tiol a alta concentracion, lava con solvente organico, etc. Todo esto apelando a que no importa mantener la estabilidad de las nanoparticulas.

Try to wash your nanoparticles with ethanol or acetone after cetrifugation from reaction media

You mentioned that you have removed the remaining plant extract by cleaning process. You need to centrifuge further and decant/filter the formed nanoparticles and then dry in an oven. With that your nanoparticles purity will not be compromised. The normal characterization equipment for nanoparticles are IR, UV, SEM, XRD.