Label-free localized surface plasmon resonance biosensor composed of multi-functional DNA 3 way junction on hollow Au spike-like nanoparticles (HAuSN) for avian influenza virus detection.

In the present study, we fabricated a label-free avian influenza (AIV H5N1) detection biosensor composed of a multi-functional DNA 3 way-Junction (3 W J) on a hollow Au spike-like nanoparticle (hAuSN) using a localized surface plasmon resonance (LSPR) method. To construct the multi-functional DNA (MF-DNA) as a bioprobe, the 3 W J was introduced. The proposed AIV detection bioprobe should contain three functionalities: target recognition, signal amplification, and connection to substrate. To achieve this goal, each piece of the DNA 3 W J was tailored to a hemagglutinin (HA) binding aptamer, FAM dye and thiol group, respectively. The assembly of each DNA 3 W J functional fragment was then confirmed by TBM-Native PAGE. Moreover, the hAuSN was immobilized on the indium-tin-oxide (ITO) substrate for LSPR measurement. The DNA 3 W J was immobilized onto the hAuSN electrode through the thiol-group of DNA 3 W J. The fabricated DNA 3 W J/hAuSN heterolayer on the ITO substrate was investigated by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). LSPR experiments were conducted to confirm HA protein binding to the DNA 3 W J/ hAuSN -modified electrode. The proposed biosensor can detected the HA protein in PBS buffer (LOD: 1 pM) as well as in the diluted chicken serum (LOD: 1 pM). The present study details a label-free, simple fabrication method consisted of DNA 3 W J/ hAuSN heterolayer that uses easy-to-tailor elements to detect not only AIV but also various viruses detection platform easily.

Fabrication of electrochemical biosensor composed of multi-functional DNA structure/Au nanospike on micro-gap/PCB system for detecting troponin I in human serum.

Acute myocardial infarction (AMI) is one of the most serious diseases affecting human beings. In this study, in order to rapidly detect AMI disease, the authors fabricated a label-free electrochemical biosensor composed of a multi-functional DNA structure on Au nanospike (AuNS) with a fabricated Au micro-gap electrode which was incorporated with a PCB chip in order to detect cardiac troponin I (cTnI). As a bioprobe, the DNA 3 way-junction (3WJ) was introduced, because the DNA 3WJ has three arms for embodying the multi-functionality. Each piece of DNA was assembled to simultaneously form the DNA 3WJ for cTnI detection, signal transduction, and immobilization, respectively. The assembled DNA 3WJ structure was confirmed by Native-TBM PAGE. Moreover, in order to increase the electrochemical signal sensitivity, AuNS was prepared. The Au micro-gap array is fabricated with a printed circuit board (PCB) chip in order to control each micro-gap electrode panel selectively so as to detect low volumes of cTnI. Then, the DNA strucuture on pAuNS-modified electrode was prepared using the layer-by-layer (LbL) assembly method. FE-SEM and AFM were used to investigate the modified-surface morphology. The cyclic voltammetry (CV) was measured to confirm the cTnI binding to DNA 3WJ-modified electrode. cTnI was detected in the HEPES solution and human serum, respectively. The LOD result exhibited 1.0 pM in HEPES solution and 1.0 pM in 20% diluted human serum, respectively. In addition, the selectivity test was carried out with various proteins as the control experiment. The present study showed label-free, simple fabrication, and easy-to-tailor detection elements for cTnI.