Table 1.

The FFF techniques and their possible applications to nanomaterials for drug delivery

Technique	Separation principle	Separation depends on	Eluent	Applications to drug delivery systems	Ref
ThFFF	Temperature gradient	D, DT	Mostly organic (few examples in aqueous buffer)	Separate polymeric micelles according to size and polymer composition	[191, 192]
GrFFF and SdFFF (CF3)	Gravitational force	m, δ, D	Mostly free (more than FlFFF, since there is no membrane)	Separate particles from larger aggregates, “differential FFF”	[76, 128][118]
ElFFF	Electrical force	μ, D	Deionized water	Separate particles with different surface functionalization and z-potential	[193]
EAF4	Electrical force + secondary eluent flow	μ, D	Mostly free	Separate particles with different surface functionalization and z-potential	[75]
FlFFF (AF4 or HF5)	Secondary eluent flow	D	Mostly free	See main text	–-

D diffusion coefficient, D_T thermal diffusion coefficient, m molar mass, δ density, μ electrophoretic mobility