Fig. 7. Fluorescence quenching of ctDNA with different concentrations of (a) GO–Ag and (b) GO–Ag–TiO₂@ZnO in Tris–HCl buffer; λ_ex = 260 nm; (c) Stern–Volmer plots this figure has been reproduced from ref. 143 with permission from Royal Society of Chemistry, Copyright 2019].