BDNF and Alzheimer disease: Novel aptamers have been identified against several well-validated AD biomarkers—like microRNA-193b (miR-193b), GFAP [138], brain-derived neurotrophic factor (BDNF) [139], BACE1 [140], and tumor necrosis factor-alpha (TNF-α) [141].Currently, Gli-233 and Gli-55 are the only aptamers reported in the literature for the specific targeting of GFAP protein and applied to astrocytomas.