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A sensitive immunosensor for the detection of pregnancy marker, human chorionic gonadotropin hormone (hCG), was developed using the direct electrical detection of Au nanoparticles. We utilized disposable screen-printed carbon strips (SPCSs) for the development of our immunosensor, which provided cost-effective tests with the required antigen sample volume as small as 2 mL. After the recognition reaction between the surface-immobilized primary antibody and hCG, the captured antigen was sandwiched with a secondary antibody that was labeled with Au nanoparticles. Au nanoparticles were exposed to a preoxidation process at 1.2 V for 40 s, which was subsequently followed with a reduction scan on the same surface using differential pulse voltammetry (DPV). We could observe Au nanoparticle-labeled antigen-antibody complexes immobilized on the surface of SPCS using scanning electron microscopy (SEM). Additionally, the number of Au nanoparticles on the immunosensor was determined using SEM images, and showed a linear relationship with the current intensity obtained from the DPV measurements with a detection limit of 36 pg/mL hCG (612 fM, 3.6 Â 10 À4 IU/mL). Our immunosensor system, a combination of the screenprinting technology with Au nanoparticles provides a promising biosensor for various applications in life sciences.

In this study, we are reporting for the first time the elucidation of single nucleotide polymorphisms (SNPs) of clinically important alleles from consenting human subjects using a disposable electrochemical printed (DEP) chip in connection with differential pulse voltammetry (DPV) and a redox active molecule Hoechst 33258 [H33258, 2'-(4-hydroxyphenyl)-5-(4-methyl-1-piperazinyl)-2,5'-bi(1H-benzimidazole)]. Post-PCR products were analyzed directly without any purification process. The aggregation of the DNA-H33258 complex causes a significant drop in the peak current intensity of H33258 oxidation. The phenomenon of DNA aggregation induced by H33258 in addition to changes in anodic current peak are used to detect SNPs. Since laborious probe immobilization was not required, our biosensor offers several benefits due to its simplicity and rapid response as a promising device for genetic analysis.

Our novel QCA was rapidly and easily performed at the point of care and improved the rate of successful AVS.