Two types of organic-inorganic hybrid structure-related lanthanide (Ln)-included selenotungstates (Ln-SeTs) [H2N(CH3)2]11Na7[Ce4(H2PTCA)2(H2O)12(HICA)]2[SeW4O17]2[W2O5]4[SeW9O33]4·64H2O (1, H3PTCA = 1,2,3-propanetricarboxylic acid, H2ICA = itaconic acid) and [H2N(CH3)2]6Na4[Ln4SeW8(H2O)14(H2PTCA)2O28] [SeW9O33]2·31H2O [Ln = Pr3+ (2), Nd3+ (3)] were obtained by Ln nature control. The primary frameworks of 1-3 are composed of trivacant Keggin-type [B-α-SeW9O33]8- and [SeW4Om]n- [Ln = Ce3+ (1), m = 17, n = 6; Ln = Pr3+ (2), Nd3+ (3), m = 18, n = 8] fragments bridged by organic ligands and Ln clusters. Intriguingly, Ln nature results in the degradation of hexameric 1 to trimeric 2-3. Besides, 1@DMDSA and 3@DMDSA composites (DMDSA·Cl = dimethyl distearylammonium chloride) were prepared through the cation exchange method, which were then reorganized to form two-dimensional (2D) honeycomb thin films by the breath figure method. Using these honeycomb thin films as electrode materials, the aptasensors were further established by utilizing methylene blue as an indicator and cDNA and Au nanoparticles as signal amplifiers to enhance the response signal so as to realize the purpose of ochratoxin A (OTA) detection. This work provides a new platform for detecting OTA and explores the application potential of POM-based composites in biological and clinical analyses.
Keywords: aptasensor; electrochemistry; lanthanide substituted selenotungstate; polyoxometalate; structural control.