Fig 2: (A) Visual detection of CA125 at its gradually increasing concentrations in competitive format through NALFA where 10 μM aptamer was immobilized on NC laminate, and AuNPs- CA125 conjugate was applied on a reservoir matrix. The assay was run using varying concentrations (0–200 U/mL) of CA125 in 0.1 M phosphate buffer as the test sample. (B) Quantification of NALFA using ImageJ software by calculating average RGB intensities.

Fig 3: Binding study of CA125 with aptamer 2.26 using (A) Dot ELASA where CA125 was immobilized on nitrocellulose membrane, blocked, and then incubated with biotinylated apt2.26 followed by incubation with streptavidin-HRP. DAB/H2O2 was used as a peroxidase substrate resulting in a brown colored product. (B) NALFA (N = 4 for both assays) where 10 μM aptamer was immobilized on NC laminate, and AuNPs- CA125 conjugate was applied on a reservoir matrix. The assay was run using PBS containing BSA and Tween-20.

Fig 4: Apt 2.26-CA125 binding using differential pulse voltammetry.

Fig 5: Serum stability profiling: (A) PCR amplified DNA and (B) its single-stranded form before amplification, after treatment with 50%v/v normal human female serum. Effect of different salt concentrations on aptamer-CA125 binding: (C) negative controls and (D) treated aptamer (lane 1: ladder, lane 2: 0.2 M NaHCO3 with 0.5 M NaCl, lane 3: 100 mM NaCl and 5 mM MgCl2, lane 4: milli-Q water as positive control; (E) Binding—saturation curve for determination of KD. The original gel images have been provided in Figures S4, S5.