Table 3.

Summary table of the smart theranostics discussed in this section and their enzyme-responsive mechanisms

Smart theranostic	Structure of responsive linker	Responsive trigger	Responsive Mechanism	Ref
ATF-IONP-Gem		Enzyme (cathepsin B)	Cathepsin B (1 µM): Cleavage of GFLG tetrapeptide linker induces release of anticancer drug Gem from system.	157
pHPMA-Gd-PTX-Cy5.5		Enzyme (cathepsin B)	Cathepsin B (2.8 µM): Cleavage of GFLG tetrapeptide linker induces release of anticancer drug PTX from system.	158
BP-PTX Gd NPs		Enzyme (cathepsin B)	Cathepsin B (2.8 µM): Cleavage of GFLG linkers connecting branched pHPMA polymers and binding PTX to the system induces nanoparticle disassembly and release of anticancer drug PTX.	28
T-MAN		Enzyme (MMP-2)	MMP-2 (10 nM): Cleavage of GGFLGVRGK peptide results in the release of quencher QSY21 from T-MAN and increase of the fluorescent signal intensity of Cy5.5.	162