fully-automated-centrifugal-microfluidic-device-for-ultrasensitive

Fully Automated Centrifugal Microfluidic Device for Ultrasensitive Protein Detection from Whole Blood

Enzyme-linked immunosorbent assay (ELISA) is a promising method to detect small amount of proteins in biological samples. The devices providing a platform ...

School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, Republic of Korea

Photoelectrochemical sensors based on hierarchically structured titanium dioxide (TiO2) nanofibers (NFs) were fabricated by combination of electrospinning, carbon microelectromechanical systems (MEMS), and hydrothermal reaction. During the electrospinning step, a rotating drum collector was used to align and position NFs of titanium tetraisopropoxide (TTIP) in polyvinylpyrrolidone (PVP) on top of a carbon-MEMS structure. Following calcination under vacuum, a stable ohmic contact was obtained between suspended TiO2-carbon NFs (TiO2/C NF) and the carbon electrodes. Subsequent to this, a hierarchical nanostructure of TiO2 nanowires (TiO2 NWs) was hydrothermally synthesized onto the TiO2/C NFs and successfully utilized as UV and pH sensors. This is the first demonstration of a semiconductor-based nanofiber sensor suspended on carbon electrodes that has been achieved by a relatively simple and cost-effective electrospinning method. Furthermore, these sensors demonstrate a high sensitivity, as well as a stable ohmic contact, due to the large surface area of the TiO2 NWs and the carbon-carbon contact between the suspended TiO2/C NFs and carbon electrodes.

Hierarchically structured suspended TiO2 nanofibers for use in UV and pH sensor devices.

ELISA-based devices are promising tools for the detection of low abundant proteins in biological samples. Reductions of the sample volume and assay time as well as full automation are required for their potential use in point-of-care diagnostic applications. Here, we present a highly efficient lab-on-a-disc composed of a TiO2 nanofibrous mat for sensitive detection of serum proteins with a broad dynamic range, with only 10 μL of whole blood within 30 min. The TiO2 nanofibers provide high specific surface area as well as active functional groups to capture large amounts of antibodies on the surface. In addition, the device offers efficient mixing and washing for improving the signal-to-noise ratio, thus enhancing the overall detection sensitivity. We employ the device for the detection of cardiac biomarkers, C-reactive protein (CRP) and cardiac troponin I (cTnI), spiked in phosphate-buffered saline (PBS) as well as in serum or whole blood. The device exhibited a wide dynamic range of six orders of magnitude from 1 pg mL(-1) (~8 fM) to 100 ng mL(-1) (~0.8 pM) and a low detection limit of 0.8 pg mL(-1) (~6 fM) for CRP spiked in CRP-free serum and a dynamic range of 10 pg mL(-1) (~0.4 pM) to 100 ng mL(-1) (~4 nM) with a detection limit of 37 pg mL(-1) (~1.5 pM) for cTnI spiked in whole blood.

Electrospun TiO2 nanofiber integrated lab-on-a-disc for ultrasensitive protein detection from whole blood.

Recently, there has been increased interest in electrospun-titanium dioxide nanofibers (TiO2 NFs) as antibacterial agents owing to their advantages, such as simple and cost-effective fabrication processes, and high surface areas. However, the photocatalytic effects of TiO2 NFs are relatively low because of their low-ordered crystalline structure, and the antibacterial effect is only effective under UV illumination owing to their large band-gap energy. In this paper, we have demonstrated a significantly enhanced antibacterial activity of hierarchical anatase TiO2 NFs against Staphylococcus aureus in the presence of UV light. Furthermore, the uniform deposition of a large quantity of Ag nanoparticles on the surface of the TiO2 NFs ensured a significant enhancement of the antibacterial performance, even under dark conditions. These results were obtained by exploiting the enhanced photocatalytic effect achieved through control of the crystallinity, as well as the enhanced surface area of the nanomaterials.

Article	Year
Hierarchically structured suspended TiO2 nanofibers for use in UV and pH sensor devices. ACS applied materials & interfaces\| PubMed ID: 25010666	2014
Electrospun TiO2 nanofiber integrated lab-on-a-disc for ultrasensitive protein detection from whole blood. Lab on a chip\| PubMed ID: 25407164	2015
Significantly enhanced antibacterial activity of TiO2 nanofibers with hierarchical nanostructures and controlled crystallinity. The Analyst\| PubMed ID: 25426595	2015

Yang-Seok Park

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