Table 3.

CNT-based PAI. Each piece of research is classified by CNT types, modification, abbreviation, theragnosis multimodalities, PA signal enhancement, novelties, maximum cytotoxicity concentration, and test species. CNTR, carbon nanotube ring; LBL, layer-by-layer; CD, carbon dot; CND, carbon nanodot; CNS, carboneous nanosphere; Cur, curcumin; HA, hyaluronic acid; SLN, sentinel lymph node; PDDA, poly (diallyl dimethyl ammonium chloride); PLGA, poly(lactic-co-glycolic acid); PL-PEG5000, polyethylene glycol-5000 grafted phospholipid; PSS, poly (sodium 4-styrene sulfonate); RGD, cyclic Arg-Gly-Asp.

Types	Materials Modification	Multimodalities	PA Enhancement (Fold/Control)	Novelties	Cytocompatible Concentration	Test Species	Ref.
MWCNT	RGD peptides and silica/AuNR	PTT	N/A	Good water solubility, cell targetability, and in vivo gastric cancer cell imaging	≤200 μg/mL	MGC803, GES-1, MGC803-BALB/c nude	[142]
SWCNT	RGD peptides and silica/AuNR	PTT	N/A	Good water solubility, cell targetability, and in vivo gastric cancer cell imaging	≤200 μg/mL	MGC803, GES-1, MGC803-BALB/c nude	[142]
	N/A	N/A	4/blood	SLN visualization	N/A	Sprague–Dawley rat	[144]
	PLGA	Micro CT	N/A	Availability as tissue engineering scaffold multiscale PAI	N/A	N/A	[145]
	ICG	FL	2/ICG at mouse breast tumor	Detailed optical characterization of SWCNT-reinforced probes	N/A	4T1 Luc, 4T1 Luc-BALB/c	[146]
	ICG and RGD	N/A	300/SWCNT at mouse subcutaneous region	αvβ3-integrin-mediated cancer targetability and enhanced optical absorbance signal duration	N/A	Nude	[147]
	RGD and PL-PEG5000	N/A	8/SWCNT at ex vivo mouse tumor	Tumor targetability, non-invasive imaging of tumor, and absorbance in lower NIR window	N/A	U87MG-BALB/c nude	[148]
	CNTR, redox-active polymer, and AuNP	Optical microscopy, Raman microscopy	6/CNTR at water	Signal enhancement via local electrical field by SERS	N/A	U87MG cell and U87MG-nude	[151]
	PDDA, PSS, AuNP, and silica microsphere	Raman microscopy	N/A	AuNP–CNT multilayer assemble by LBL technique, strong absorption in NIR and visible region, and ex vivo mouse brain imaging	N/A	Human fibroblast C57Bl/6	[155]