Flow field-flow fractionation with multiangle light scattering detection for the analysis and characterization of...

Chemical modifications of nanoparticles (NPs) are often necessary to improve their features as spectroscopic tracers or chemical sensors, or to increase water solubility and biocompatibility of NPs for applications in nano-biotechnology. The description of newly designed functional NPs is rapidly expanding. However, the full exploitation of technologies based on functional NPs requires accurate, precise, and rugged methods for their analysis and characterization. When quality control protocols for industrial NP production are required, these methods must be applied on a routine basis. Since many properties of functional NPs are size-dependent, particle size distribution analysis provides fundamental information. The actual presence and distribution of functional groups in the NPs as well as their chemical features in the nanodispersed state are also fundamental aspects to be additionally analyzed. However, all these tasks cannot be afforded by a single method. Separation methods are necessary to isolate the newly synthesized NPs from the reagents in solution, and then coupled methods can characterize the isolated NPs. Flow field-flow fractionation (F4) is increasingly used as a mature separation method to size-sort and isolate NPs for their further analysis or size characterization by multiangle light scattering (MALS) detection. In this work, firstly the application of F4-MALS to different types of functional NPs is concisely overviewed. We then illustrate our recent applications of F4-MALS coupled with spectroscopic methods for the analysis and characterization of functional NPs. We finally provide an outlook of what we believe are the trends to make F4 soon become the required method in routine-based analytical platforms for quality control protocols of industrial-scale, functional NP production.