Label-free determination of thyroglobulin using template-probe double imprinted composites

Abstract Thyroglobulin (Tg) is an important index for the surveillance of differentiated thyroid carcinoma, and yet sensitive and specific protein detection still faces challenges in both biomedical research and clinical diagnosis. We described a novel approach to synthesize molecular imprinting polymers (MIPs)/hemin-graphene nanosheets (H-GNs) composites on the paper, using Tg and 3,3′,5,5′-tetramethylbenzidine (TMB, probe) as double templates. H-GNs with intrinsic properties can initiate the free-radical polymerization to prepare MIPs and catalyze the coloration of peroxidase substrates such as TMB for colorimetric detection. Template-probe double imprinting strategy enhanced the accessibility of the probe to the catalytic interface without interfering the specific recognition of template molecule. Under the optimized conditions, the gray intensity was proved to be proportional to the concentration of Tg in the range of 0.7-100 ng mL-1 with a detection limit of 0.1 ng mL-1 (1.5 fM). Anti-Tg antibodies and sample matrix did not affect the determination of the target protein, nor did they enhance the background noise. The use of paper-based device exhibited the advantages of low cost, easy handling and portability. It was supposed to be applied for Tg determination in serum to evaluate persistent or recurrent differentiated thyroid carcinoma.