Sangjin Oh

A plasmon-assisted fluoro-immunoassay using gold nanoparticle-decorated carbon nanotubes for monitoring the influenza virus

A plasmon-assisted fluoro-immunoassay (PAFI) was developed for the detection of the influenza virus by using Au nanoparticle (Au NP)-decorated carbon nanotubes (AuCNTs) that were synthesized using phytochemical composites at room temperature in deionized water. Specific antibodies (Abs) against the influenza virus were conjugated onto the surface of AuCNTs and cadmium telluride quantum dots (QDs), which had a photoluminescence intensity that varied as a function of virus concentration and a detection limit of 0.1 pg/mL for all three types of influenza viruses examined. The clinically isolated influenza viruses (A/Yokohama/110/2009 (H3N2)) were detected in the range of 50-10,000 PFU/mL, with a detection limit of 50 PFU/mL. From a series of proof-of-concept and clinical experiments, the developed PAFI biosensing system provided robust signal production and enhancement, as well as an excellent selectivity and sensitivity for influenza viruses. This nanoparticle-based technique could be potentially developed as an efficient detection platform for the influenza virus.

Magnetoplasmonic Nanomaterials for Biosensing/Imaging and in Vitro/in Vivo Biousability

Most commonly magnetoplasmonic nanoparticles (MagPlas NPs) are unique composites combining magnetic and plasmonic materials within a confined nanoscale area that simultaneously show magnetic and plasmonic characteristics. They generally use Fe, Co, or Ni-based magnetic materials and noble-metal (e.g., Au, Ag, Cu, or Pt) plasmonic components, comprising a precious metal layer along a magnetic core or the inverse structure. MagPlas NPs are emerging multi-functional materials in the fields of nanoscale optoelectronics, anisotropic optics, electronics, optical sensing, and imaging. Their potential for sensing, targeting, and multimodal imaging is highly attractive for nanomedicine and nanobiotechnology. Because they possess suitable biocompatibility, MagPlas NPs have also been used in biosensor systems, hyperthermia, and magnetic resonance imaging (MRI) applications. This relatively new field of science employs MagPlas NPs in biological systems, which have great application potential in biomedicine and biomed...

Cytotoxicity and Gene Expression in Sarcoma 180 Cells in Response to Spiky Magnetoplasmonic Supraparticles

Multifunctional nanoparticles (NPs) have been designed for a variety of cell imaging and therapeutic applications, and the study of their cellular interactions is crucial to the development of more efficient biomedical applications. Among current nanomaterials, concave core-shell NPs with complex angled geometries are attractive owing to their unique shape-dependent optical and physical properties as well as different tendency for cell interaction. In this study, we investigated the morphology effect of spiky gold-coated iron oxide supraparticles (Fe3O4@Au SPs) on cytotoxicity and global gene expression in sarcoma 180 cells. Cells treated for 7 days with spiky supraparticles (SPs) at concentrations up to 50 μg/mL showed >90% viability, indicating that these NPs were nontoxic. To shed light on the differences in cytotoxicity, we monitored the expression of 33,315 genes using microarray analysis of SP-treated cells. The 171 up-regulated genes and 181 down-regulated genes in spiky SP-treated cells included Il1b, Spp1, Il18, Rbp4, and Il11ra1, where these genes are mainly involved in cell proliferation, differentiation, and apoptosis. These results suggested that the spiky Fe3O4@Au SPs can induce noncytotoxicity and gene expression in tumor cells, which may be a promising cornerstone on which to base related research such as cyto-/genotoxicology of nanomaterials or the design of nanoscale drug carriers.

Synthesis of Gold Nanoparticles with Buffer-Dependent Variations of Size and Morphology in Biological Buffers

The demand for biologically compatible and stable noble metal nanoparticles (NPs) has increased in recent years due to their inert nature and unique optical properties. In this article, we present 11 different synthetic methods for obtaining gold nanoparticles (Au NPs) through the use of common biological buffers. The results demonstrate that the sizes, shapes, and monodispersity of the NPs could be varied depending on the type of buffer used, as these buffers acted as both a reducing agent and a stabilizer in each synthesis. Theoretical simulations and electrochemical experiments were performed to understand the buffer-dependent variations of size and morphology exhibited by these Au NPs, which revealed that surface interactions and the electrostatic energy on the (111) surface of Au were the determining factors. The long-term stability of the synthesized NPs in buffer solution was also investigated. Most NPs synthesized using buffers showed a uniquely wide range of pH stability and excellent cell viability without the need for further modifications.

Magnetic Nanozyme-Linked Immunosorbent Assay for Ultrasensitive Influenza A Virus Detection

Rapid and sensitive detection of influenza virus is of soaring importance to prevent further spread of infections and adequate clinical treatment. Herein, an ultrasensitive colorimetric assay called magnetic nano(e)zyme-linked immunosorbent assay (MagLISA) is suggested, in which silica-shelled magnetic nanobeads (MagNBs) and gold nanoparticles are combined to monitor influenza A virus up to femtogram per milliliter concentration. Two essential strategies for ultrasensitive sensing are designed, i.e., facile target separation by MagNBs and signal amplification by the enzymelike activity of gold nanozymes (AuNZs). The enzymelike activity was experimentally and computationally evaluated, where the catalyticity of AuNZ was tremendously stronger than that of normal biological enzymes. In the spiked test, a straightforward linearity was presented in the range of 5.0 × 10-15-5.0 × 10-6g·mL-1 in detecting the influenza virus A (New Caledonia/20/1999) (H1N1). The detection limit is up to 5.0 × 10-12 g·mL-1 only by human eyes, as well as up to 44.2 × 10-15 g·mL-1 by a microplate reader, which is the lowest record to monitor influenza virus using enzyme-linked immunosorbent assay-based technology as far as we know. Clinically isolated human serum samples were successfully observed at the detection limit of 2.6 PFU·mL-1. This novel MagLISA demonstrates, therefore, a robust sensing platform possessing the advances of fathomable sample separation, enrichment, ultrasensitive readout, and anti-interference ability may reduce the spread of influenza virus and provide immediate clinical treatment.

In vivo feasibility test using transparent carbon nanotube-coated polydimethylsiloxane sheet at brain tissue and sciatic nerve

Carbon nanotubes, with their unique and outstanding properties, such as strong mechanical strength and high electrical conductivity, have become very popular for the repair of tissues, particularly for those requiring electrical stimuli. Polydimethylsiloxane (PDMS)-based elastomers have been used in a wide range of biomedical applications because of their optical transparency, physiological inertness, blood compatibility, non-toxicity, and gas permeability. In present study, most of artificial nerve guidance conduits (ANGCs) are not transparent. It is hard to confirm the position of two stumps of damaged nerve during nerve surgery and the conduits must be cut open again to observe regenerative nerves after surgery. Thus, a novel preparation method was utilized to produce a transparent sheet using PDMS and multiwalled carbon nanotubes (MWNTs) via printing transfer method. Characterization of the PDMS/MWNT (PM) sheets revealed their unique physicochemical properties, such as superior mechanical strength, a certain degree of electrical conductivity, and high transparency. Characterization of the in vitro and in vivo usability was evaluated. PM sheets showed high biocompatibility and adhesive ability. In vivo feasibility tests of rat brain tissue and sciatic nerve revealed the high transparency of PM sheets, suggesting that it can be used in the further development of ANGCs.

Chiral zirconium quantum dots: A new class of nanocrystals for optical detection of coronavirus

Abstract A synthetic way of chiral zirconium quantum dots (Zr QDs) was presented for the first time using L(+)-ascorbic acid acts as a surface as well as chiral ligands. Different spectroscopic and microscopic analysis was performed for thorough characterization of Zr QDs. As-synthesized QDs exhibited fluorescence and circular dichroism properties, and the peaks were located at 412 nm and 352 nm, respectively. MTT assay was performed to test the cytotoxicity of the synthesized Zr QDs against rat brain glioma C6 cells. Synthesized QDs was further conjugated with anti-infectious bronchitis virus (IBV) antibodies of coronavirus to form an immunolink at the presence of the target analyte and anti-IBV antibody-conjugated magneto-plasmonic nanoparticles (MPNPs). The fluorescence properties of immuno-conjugated QD–MP NPs nanohybrids through separation by an external magnetic field enabled biosensing of coronavirus with a limit of detection of 79.15 EID/50 μL.