SPR sensor based on polyelectrolyte complexes with DNA inclusion

[Display omitted] •Polyelectrolyte complexes were assembled on SPR chip and monitored layer-by-layer.•The efficiency of assembling depended on primary modification of gold.•Introduction of DNA allows detection of its oxidative damage and intercalation.•The role of layer flexibility and geometry in SPR signaling is discussed. Polyelectrolyte complexes offer unique possibilities for assembling nanostructures with recognition properties that find increasing application in various sensors for detection of biochemical interactions. In this work, the assembling of multilayers consisted of synthetic polyelectrolytes and DNA was monitored by changes in the SPR angle shift recorded after addition of each layer. For the first time, it was shown that primary modification of the Au surface influences the rate of the multilayer assembling and the shape of appropriate dependence of the SPR signal on the number of polyelectrolyte layers. Changes in the SPR signal were referred to the difference in rigidity of the layers and variation of the roughness of the surface reached by combination of the polyelectrolytes with different flexibility of the main chain and different distribution of the charges along the chain. The polyelectrolytes assembled make it possible to detect the DNA source and specific DNA interactions including its thermal and oxidative denaturation and intercalation with doxorubicin. The incubation of the SPR sensor in the doxorubicin solution made it possible to estimated the drug concentration in the range from 1∙10−12 to 1∙10-7 M (limit of detection 7∙10-13 M). Besides, the SPR sensor can be used for estimation of protective effect of antioxidants as was shown on the example of ascorbic acid suppressing DNA oxidation with reactive oxygen species.