Showing papers by "Kyusik Yun published in 2019"

Kaempferol conjugated gold nanoclusters enabled efficient for anticancer therapeutics to A549 lung cancer cells.

Abstract: Background: Kaempferol (K) is a recognized anticancer drug that can conjugate with small-size gold nanoclusters (AuNCs). Materials and methods: K-AuNCs were synthesized and their use as an anticancer drug was explored using A549 lung cancer cells. Colony formation and cell migration assays were carried out. The morphology of the K-AuNCs treated A549 cells was explored using bio-atomic force microscopy. Results: The K-AuNCs were 1-3 nm in diameter and emitted strong fluorescent at 650 nm following excitation at 550 nm. The stretching and bending nature of the K-AuNCs were analyzed by the Fourier transform infrared spectroscopy. The presence of kaempferol in the AuNCs were confirmed by the PL spectroscopy. Conclusion: The synthesized K-AuNCs mainly targeted and damaged the nuclei of the cancer cells. This composite nanocluster was less toxicity to the normal human cell and higher toxicity to the A549 lunch cancer cell and these material is potential for anticancer drug delivery and bio imaging applications.

A new device concept for bacterial sensing by Raman spectroscopy and voltage-gated monolayer graphene

Abstract: Electron–phonon coupling in monolayer graphene results in a modification of its Raman spectra upon charge transfer processes induced by interaction with its chemical environment or the presence of strain or defects in its structure. Modification of Raman spectra is examined in order to develop ultra-sensitive biosensing techniques for the detection, identification, differentiation and classification of bacteria associated with infectious diseases. Specifically, the electrochemical properties of top gated monolayer graphene on SiO2/Si substrates, in the absence and presence of interaction with Gram-positive bacteria (Enterococcus faecalis, Bacillus subtilis) and Gram-negative bacteria (Escherichia coli and Salmonella typhimurium), are probed by Raman spectroscopy in an applied voltage range from 0 V to 3 V. Bacteria and monolayer graphene interactions are thus electrostatically tuned. The resulting correlation of specific bacterial chemical properties and Raman spectral characteristics is reported, along with density functional theory simulations of the charge transfer mechanism. The intensities of the G and D Raman vibrational modes are modulated as a function of the applied voltage in the presence of bacteria, but remain unchanged in bare monolayer graphene. A fingerprint region is also identified in the range of 200 cm−1 to 600 cm−1, with disulfide bonds observed at 490 cm−1, associated with bacterial membrane proteins. Significantly, such observations are detected even in the absence of bacterial culturing, a time-consuming step.

The Synergistic Effect of Zinc Ferrite Nanoparticles Uniformly Deposited on Silver Nanowires for the Biofilm Inhibition of Candida albicans

Abstract: Near-monodisperse zinc ferrite nanoparticles (ZnFe2O4 NPs) are synthesized by a co-precipitation method and deposited on the surface of silver nanowires (AgNWs), employing a stepwise solution method. The resulting hybrid nanostructures (ZnFe2O4@AgNWs) show a thin and uniform layer of ZnFe2O4 NPs at an optimum weight ratio of 1:6 between the two component nanostructures. The hybrid nanostructures retain the high crystal quality and phase purity of their constituents. It is demonstrated that the ZnFe2O4@AgNWs hybrid nanostructures are effective at inhibiting the biofilm formation of Candida albicans cells. The biofilm inhibition activity of the hybrid nanostructures is estimated to be more than 50% at a low concentration of 100 µg/mL from both crystal violet assay and XTT assay, which are more than 8-fold higher than those of pure AgNWs and ZnFe2O4 NPs. This greatly enhanced biofilm inhibition activity is attributed to the ZnFe2O4 NPs-carrying membrane penetration by AgNWs and the subsequent interaction between Candida cells and ZnFe2O4 NPs. These results indicate that the ZnFe2O4@AgNWs hybrid nanostructures have great potential as a new type of novel antibiofilm agent.

Cucurbituril-Based Reusable Nanocomposites for Efficient Molecular Encapsulation

Abstract: Cucurbituril (CB) has recently been employed in many fields, including water purification, solar cells, energy conversion, and biomedical engineering. However, the poor solubility of CB poses a serious obstacle to the further development of CB applications. To enhance the solubility of members of the CB family (CB[5–8]) by preventing self-aggregation in aqueous solutions, the synthesis of highly stable, rapid, and water-dispersible particles is presented in this paper based on a simple process that employs a nanocomposite composed of CB and amine-modified diatomaceous earth (DA). CB can be coated onto the surface of the DA and stabilized to produce a novel material that is useful for various applications. The nanocomposite (CB-DA) exhibited a strong host–guest interaction, exhibiting a more than 100-fold increase in efficiency and greater stability in dye and pathogen encapsulation as a result of the host–guest interaction, electrostatic interaction, and covalent bonding. We applied CB-DA to a commerciali...

Biosynthesized Highly Stable Au/C Nanodots: Ideal Probes for the Selective and Sensitive Detection of Hg2+ Ions

Abstract: The enormous ongoing industrial development has caused serious water pollution which has become a major crisis, particularly in developing countries. Among the various water pollutants, non-biodegradable heavy metal ions are the most prevalent. Thus, trace-level detection of these metal ions using a simple technique is essential. To address this issue, we have developed a fluorescent probe of Au/C nanodots (GCNDs-gold carbon nanodots) using an eco-friendly method based on an extract from waste onion leaves (Allium cepa-red onions). The leaves are rich in many flavonoids, playing a vital role in the formation of GCNDs. Transmission electron microscopy (TEM) and Scanning transmission electron microscopy-Energy-dispersive X-ray spectroscopy (STEM-EDS) elemental mapping clearly indicated that the newly synthesized materials are approximately 2 nm in size. The resulting GCNDs exhibited a strong orange fluorescence with excitation at 380 nm and emission at 610 nm. The GCNDs were applied as a fluorescent probe for the detection of Hg2+ ions. They can detect ultra-trace concentrations of Hg2+ with a detection limit of 1.3 nM. The X-ray photoelectron spectroscopy results facilitated the identification of a clear detection mechanism. We also used the new probe on a real river water sample. The newly developed sensor is highly stable with a strong fluorescent property and can be used for various applications such as in catalysis and biomedicine.

Recent Trends in the Development of Paper-Based Diagnostic Chips for the Detection of Human Viruses

Abstract: Viral diseases account for a significant portion of global public health expenditure, and the methodologies for their rapid diagnosis are still under development. The existing diagnostic strategies for viral infections are expensive and time-consuming and provide results that may have minimal clinical impact. Hence, there is a significant interest in developing portable and inexpensive diagnostic platforms for various viral diseases and testing at point-of-care (POC) settings. This would help patients in availing timely therapy to avoid future difficulties, thus benefiting the public health sector and helping gather sufficient data for epidemiological studies to put a stop to outbreaks and epidemics involving such diseases. Among the strategies being developed, paper-based diagnostic devices have caught the attention of many researchers owing to advantages like low cost, easy handling, being disposable, and being usable at POC settings. The aim of this review is to discuss the importance of paper-based devices and recent developments in fabrication methodologies.

Dimethyl 3,3′-dithiobispropionimidate (DTBP) as a cleavable disulfide-based polymer to encapsulate nucleic acids in biological sample preparation

Abstract: Cleavable disulfide bonds are extremely valuable functional groups for numerous biological applications, including applications as antitumor treatments, gene delivery, and diagnosis. Herein, we demonstrate the use of dimethyl 3,3′-dithiobispropionimidate (DTBP) as a disulfide cleavable bond based cross-linker in nano-composites that encapsulate and release nucleic acids in sample preparation systems for disease diagnoses. We conjugated DTBP with nano-composites, such as amine group-modified diatomaceous earth (DA), which is a solid substrate, and a zinc oxide nanomultigonal shuttle (ZnO NMS) that disrupts cell membranes without chaotropic detergents and improved the quantity and purity of nucleic acids from various biological samples. After encapsulating nucleic acids, the cleavable disulfide bond of DTBP was used to release nucleic acids by breaking disulfide bonds using dithiothreitol (DTT), resulting in highly enhanced efficiency of downstream analyses without PCR inhibitors such as high salt concentrations and SDS. Therefore, nano-composites with cleavable disulfide linkages have potential for various biological applications, including disease diagnostics and therapies.