Table −3.

Some studies by Nucleobases modifications.

	Aptamer	target	Affinity (Kd)	Reference
Base modification	AMYm1 aptamer	Salivary α-amylase (sAA)	<1 nM	[152]
	Aad1 aptamer (Adenine-appended modification strategy)	human β-defensin 2	6.8 nM.	[153]
	SARS-CoV-2 aptamer	receptor-binding domain (RBD) and	1.2 nM	[153]
	SARS-CoV-2 aptamer	spike trimer of the SARS-CoV-2	1 nM	[153]
Nucleotides with Amino Acid Like Side Chains	modified thrombin aptamers (TBA)	antithrombin activity	2.94 nM	[154]
	indole modified aptamer	cycle 3 GFP	18.4 nM	[155]
Other nucleobase modifications	cubanemodified aptamers (cubamers)	Plasmodium vivax lactate dehydrogenase (PvLDH)	670 nM	[156]
	added triphosphate analogs modified by 5-chlorouracil and 7-deazaadenine bases	β-secretase 1 (BACE1- the therapeutic target of Alzheimer’s disease	10 nM	[157]