Table 1.

Comparison of in situ label-free optical imaging techniques in terms of their advantages, limitations, applications, and ability to measure binding kinetics.

Technique	Mechanism	Spatiotemporal Resolution	Biocompatibility	Cell Throughput	Applications
SPRi [26]	Detects refractive index changes on a gold-coated surface using reflected light.	Temporal: Seconds. Spatial: Medium, micrometer scale.	Moderate	Moderate	High-throughput analysis of multi-cell membrane protein–ligand interactions and macromolecule binding kinetics.
SPRM [30]	Captures reflected SPR waves with a high numerical aperture (NA) objective for single-cell resolution imaging.	Temporal: Milliseconds. Spatial: High, sub-micrometer scale.	Moderate	Low	Single-cell molecular interaction studies, especially dynamic studies of membrane proteins and glycosylation analysis.
PEIM [28]	Simultaneously records electrochemical impedance and optical SPR signals for dual-mode analysis.	Temporal: Milliseconds. Spatial: Medium, micrometer scale.	Moderate	Low	Combined electrochemical and optical analysis of membrane protein binding kinetics; suitable for electrochemical behavior studies of membrane proteins.
Edge Tracking [34]	Monitors nanoscale deformations in the cell membrane using optical detection.	Temporal: Seconds. Spatial: High, sub-nanometer scale.	High	Low	Nanoscale detection of cell membrane mechanical deformation after small-molecule binding; suitable for small-molecule binding kinetics analysis.
Surface Light Scattering Microscopy (SLSM) [45]	Detects scattered light from surface plasmon waves or evanescent waves to monitor molecular interactions.	Temporal: Milliseconds. Spatial: High, sub-micrometer scale.	High	High	High-throughput small-molecule interaction analysis; suitable for single-molecule level cell heterogeneity studies.