Table 3.

Characterization studies for nanosuspensions.

Characterization	Methods	Principle	Significance	References
Particle size and morphological evaluation	Dynamic light scattering (DLS) and photon correlation spectroscopy (PCS)	Fluctuation of Rayleigh scattering of light associated with Brownian motion of nanoparticles	Particle size (PS) and particle size distribution (PDI) measurements	[19,49]
	Optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and stomic force microscopy (AFM)	Reflection or transmission of electrons incident on the particle and the force applied to the sample by the probe	Particle size measurement, surface morphology, and three-dimensional image	[24,48,58]
Surface properties	Dynamic light scattering (DLS)	Electrophoretic mobility	Surface charge (zeta potential—ZP) measurements	[40]
Solid state (Structural) characterization	Differential scanning calorimetry (DSC) and differential thermal analysis (DTA)	Thermogravimetric analysis and physical change in the sample versus change in heat flow	Solid state form analysis (enthalpy, melting point, glass transition temperature)	[58]
	Infrared (IR) spectroscopy (mid-IR and Fourier-transformed IR spectroscopy) and Raman Spectroscopy	Change in dipole moment during molecular vibrations and in polarizability during molecular vibrations	Polymorphic form changes (analysis of amorphous, crystalline, and polymorphs)	[59]
	X-ray powder diffraction (XRPD)	Diffraction of X-rays transmitted on the sample	Polymorphic form changes (analysis of amorphous, crystalline, and polymorphs)	[60]
Rheological properties (for liquid nanosuspensions)	Viscometer and rheometer	The way a liquid flows in response to the applied force and the viscosity of a fluid	Rheological character and flow type	[48,61]
Solubility	Ultraviolet (UV) spectrophotometer and high-performance liquid spectroscopy (HPLC)	Detection of increase in saturation solubility using spectroscopy or chromatography	Increasing active substance solubility	[49,60]