Table 1.

Label-free protein-drug interaction-in-solution techniques

Techniques	Complex sample	Without surface attachment	Non-Invasive	Resolution of detection	Reproducibility	Data collection speed
Non-optical techniques
X-ray/Neutron scattering (18)	Yes	Yes	No	Protein complex	moderate	hours
Cryo-electron microscopy (19)	No	Yes	No	Atomic	moderate	hours
Optical techniques
Circular dichroism (20)	No	Yes	Yes	Protein backbone	high	minutes
Surface plasmon resonance (15)	No	No	No	Protein complex	high	minutes
Interferometry (16)	Yes	No	No	Protein complex	high	minutes
SERS (17)	Yes	No	No	Atomic	low	minutes
TRIP	Yes	Yes	Yes	Atomic	high	minutes