Baf293

All oligonucleotides were purchased from Eurofins Genomics (Luxembourg, Luxembourg). The sequences are indicated in the Supplementary Materials Table S1.
Phenazine methosulfate (PMS), 2,6-dichlorophenolindophenol (DCIP), d(+)-glucose, sodium chloride, 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris), glycerol, and Tween-20 were purchased from Kanto Chemical Co. Inc. (Tokyo, Japan). Kanamycin sulfate and d-desthiobiotin were purchased from Sigma-Aldrich Co. LLC (St. Louis, MO, USA). A self-assembled monolayer (SAM) forming thiol reagent (dithiobis(succinimidyl undecanoate)) was purchased from Dojindo Laboratories Co., Ltd. (Kumamoto, Japan). LB broth, the bacterial host strain Escherichia coli BL21(DE3), and the expression vector pET30c(+) were purchased form Merck KGaA (Darmstadt, Germany). Anti-VEGF antibodies (MAB293 and BAF293) were purchased from R&D Systems, Inc. (Minneapolis, MN, USA). Gold and platinum wires were purchased from TANAKA Kikinzoku (Tokyo, Japan). A silver/silver chloride (3M NaCl) reference electrode RE-1B (Ag/AgCl) was purchased from BAS Inc. (Tokyo, Japan).

Immunoassay 96-well plates were coated with Exon8apab antibody (25 µg/ml in 1× PBS, 100 μl/well) and left overnight at room temperature. After washing in triplicate (0.05 % Tween^® in 1× PBS, 200 µl/well), immunoassay plates were blocked (1 % Bovine Serum Albumin in 1× PBS, 200 µl/well) and incubated at 37 °C for minimum of 2 h. The plates were washed and samples added, using recombinant human VEGF-A₁₆₅ (840164, R&D Systems) as a serial dilution control standard. Samples were assessed in triplicate (100 µl/well, diluted in 1 %BSA/PBS). The plate was then incubated at 37 °C for 2 h with shaking.
Following washing, biotinylated goat anti-human panVEGF-A detection antibody (BAF293, R&D Systems) was added at 100 ng/ml in 1 %BSA/PBS (100 µl/well). The plates were then incubated once more at 37 °C for 2 h. Following washing, HRP-conjugated streptavidin was added (1:200 in 1 %BSA/PBS, 100 µl/well, 890803, R&D Systems) and incubated without light exposure or agitation for 30 min at RT. The plates were washed once more, and HRP ELISA substrate (100 µl/well, DY999, R&D Systems) was added before a final incubation without light exposure at RT for 15–30 min. A stop solution (1 M H₂SO₄, 50 µl/well) was then added directly to the substrate and resultant colour change measured at 450 nm using an Opsys MR plate reader (Dynex, USA).