Table 1.

Summary of melanin-based contrast agents for optoacoustic imaging.

Contrast Agent	Description	Size (nm)	Target	Principal Applications	Ref.
PEG-MNP	Pegylated polydopamine nanoparticles	50		3D OA vascular imaging	[29]
PEG-MNP	Linear polydopamine nanoparticles	-		OA vascular imaging	[30]
PEG-MNP	Melanin nanoparticle	7–10		Assessing tumor vasculature and response to antiangiogenic therapy	[31]
PEG-MNP-CA	Pegylated polydopamine nanoparticles decorated with citraconic amide	130	Tumor acidic microenvironment	OA cancer imaging	[32]
64Cu-Fe-cRGDfC-PEG-MNP	Pegylated polydopamine nanoparticles conjugated to cyclic RGD peptide and loaded with 64Cu2+ and Fe3+	5–10	αvβ3 integrins	OA cancer imaging of integrins and multimodality imaging (OA/PET/MRI)	[33]
DOX-RGDC-PEG-MNP	Pegylated polydopamine nanoparticles conjugated to cyclic RGD peptide and loaded with doxorubicin	120	αvβ3 integrins	OA cancer imaging of integrins and chemo-photothermal therapy of tumors	[34]
125I-Pt-cRGDyC-PEG-MNP-GNR	Gold nanorods decorated with pegylated polydopamine nanoparticles conjugated to cyclic RGD peptide and loaded with cisplatin and 125I	54	αvβ3 integrins	OA cancer imaging of integrins, chemo-photothermal therapy of tumors and multimodality imaging (OA, SPECT)	[35]
ICG-Fe-PEG-MNP	Pegylated polydopamine nanoparticles loaded with indocyanine green and Fe3+	146		Photothermal therapy of tumors and multimodality imaging (OA, MRI)	[36]
SRF-PEG-MNP	Pegylated polydopamine nanoparticles loaded with sorafenib	60		Imaging-guided chemotherapy	[37]
Gd-64Cu-PEG-MNP	Pegylated polydopamine nanoparticles loaded with Gd3+ and 64Cu2+	15		Multimodality imaging (OA/MRI/PET)	[38]
Fe-MNP	Polydopamine nanoparticles loaded with Fe3+	98		Multimodality imaging (OA/MRI)	[39]
MNP-CD	Melanin-decorated carbonaceous dots	40		Multimodality imaging (OA/OI)	[40]