Kyungwoo Lee

Engineering oxygen nanobubbles for the effective reversal of hypoxia

Abstract Hypoxia, which results from an inadequate supply of oxygen, is a major cause of concern in cancer therapy as it is associated with a reduction in the effectiveness of chemotherapy and radiotherapy in cancer treatment. Overexpression and stabilization of hypoxia-inducible factor 1α (HIF-1α) protein in tumours, due to hypoxia, results in poor prognosis and increased patient mortality. To increase oxygen tension in hypoxic areas, micro- and nanobubbles have been investigated by various researchers. In the present research, lipid-shelled oxygen nanobubbles (ONBs) were synthesized through a sonication method to reverse hypoxic conditions created in a custom-made hypoxic chamber. Release of oxygen gas from ONBs in deoxygenated water was evaluated by measuring dissolved oxygen. Hypoxic conditions were evaluated by performing in vitro experiments on MDA-MB231 breast cancer cells through the expression of HIF-1α and the fluorescence of image-iT™ hypoxia reagent. The results indicated the degradation of HIF-1α after the introduction of ONBs. We propose that ONBs are successful in reversing hypoxia, downregulating HIF-1α, and improving cellular conditions, leading to further medical applications.

Oxygen-Carrying Micro/Nanobubbles: Composition, Synthesis Techniques and Potential Prospects in Photo-Triggered Theranostics

Microbubbles and nanobubbles (MNBs) can be prepared using various shells, such as phospholipids, polymers, proteins, and surfactants. MNBs contain gas cores due to which they are echogenic and can be used as contrast agents for ultrasonic and photoacoustic imaging. These bubbles can be engineered in various sizes as vehicles for gas and drug delivery applications with novel properties and flexible structures. Hypoxic areas in tumors develop owing to an imbalance of oxygen supply and demand. In tumors, hypoxic regions have shown more resistance to chemotherapy, radiotherapy, and photodynamic therapies. The efficacy of photodynamic therapy depends on the effective accumulation of photosensitizer drug in tumors and the availability of oxygen in the tumor to generate reactive oxygen species. MNBs have been shown to reverse hypoxic conditions, degradation of hypoxia inducible factor 1α protein, and increase tissue oxygen levels. This review summarizes the synthesis methods and shell compositions of micro/nanobubbles and methods deployed for oxygen delivery. Methods of functionalization of MNBs, their ability to deliver oxygen and drugs, incorporation of photosensitizers and potential application of photo-triggered theranostics, have also been discussed.

Strategies for the optimization of bead-immunoassays for the effective detection of target biomolecules

Immunoassays are analytical methods using antibody-specific reactions to analyze samples. Due to recent developments in antibody technology, the scope of potential samples has expanded to not only proteins, but also low molecular-weight compounds, carbohydrates, lipids, and microorganisms. Immunoassays have the advantage of being highly sensitive, capable of detecting small amounts, and thus have potential for application in biosensors. Immunoassays using magnetic beads have been developed and can be converted to more diverse platforms than the existing limited well plate-based assay. Furthermore, magnetic bead immunoassays detect analytical samples more quickly, and are becoming one of the most suitable immunoassay tools applicable to biosensors. However, their development requires optimization for the improvement of detection ability for specific samples. Therefore, we propose a guideline for solving detection problems occurring in magnetic bead immunoassay optimization processes. It is aimed to be a good reference, enabling researchers performing such optimization more quickly and efficiently

Synthesis of Multi-walled Carbon Nanotubes Modified with Silver Nanoparticles and Evaluation of Their Antibacterial Activities and Cytotoxic Properties

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver MWCNTs were prepared by the reductive deposition of silver from an aqueous solution of AgNO3 on the oxidized MWCNTs. Given the unique color of the CNTs, it was not possible to apply them to the minimum inhibitory concentration or mitochondrial toxicity assays to evaluate the toxicity and antibacterial properties, since they would interfere with the assays. The inhibition zone and minimum bactericidal concentration for the Ag-MWCNTs were measured and Live/Dead and Trypan Blue assays were used to measure the toxicity and antibacterial properties without interfering with the color of the CNTs.

Synthesis of Beta-glucan Nanoparticles for the Delivery of Single Strand DNA

The polysaccharide and biopolymer, beta-glucan, has been used for the purpose of enhancing immunity and its use as a drug delivery system has been diversified. Betaglucan, a triple helix structure, is unstructured to single strands by heat, DMSO or NaOH. Synthesis of beta-glucan nanoparticles using DMSO and water is easy and fast, but its size is limited. In this study, beta-glucan nanoparticles (GluNPs) were prepared by slicing beta-glucan into low molecular weight using various concentrations of Trifluoroacetic acid (TFA). TFA-treated GluNPs showed a minimum size of 250 nm. In addition, there is no abnormality in the characteristic of the functional groups of the nanoparticle surface after the acid treatment allowing GluNPs use in immune cell activation. Also, the efficiency of GluNPs as a drug or DNA carrier was confirmed by inserting ssDNA into the glucan triple helix structure. Beta-glucan nanoparticles developed in this study would be expected to be used for genetic material delivery and immune response enhancement.

Mechanisms of Salinity Control in Sea Bass

Sea bass can regulate the concentration of Na+, K+, and Cl-, among other ions, in their blood, skin, gills, and kidney. Therefore, the salinity of the water does not have a great influence on their metabolism, and sea bass can live in both sea and freshwater in accordance with the salt concentration. Most salinity control occurs in the gills, primarily through the control of chloride cells present there. The concentration of ions in the blood is controlled by the cotransporter Na+ / K+ / 2Cl- (NKCC) in the chloride cell, and the subunits of Na+ / K+ ATPase (NKA) function to maintain homeostasis. The expression of NKA is regulated by subunits of the protein FXYD, allowing the sea bass to survive in compliance with the salinity. In this way, it is possible for sea bass to live in sea and freshwater by controlling the salinity of its body using functions of various channels, proteins, and genes present in the chloride cells of sea bass. In this study, we investigated recent studies of salt control mechanisms in sea bass and their application.

Use of nanoscale materials for the effective prevention and extermination of bacterial biofilms

Biofilms have been shown to cause most human infections. The prevention and extermination of bacterial biofilms has always presented a major challenge in the clinic. The failure of traditional antibiotics and the development of bacterial resistance against these measures is on the rise. Nanoscale materials possess the advantage of presenting enhanced surface properties of bulk materials, and are emerging as effective agents for deterring microbial growth. This review article summarizes the fundamentals of bacterial growth, biofilm formation, mechanisms for antibacterial technologies, and usage of nanoparticles for the prevention and extermination of biofilms. Further research is required with respect to the appropriate usage of nanoparticles for the effective control of biofilms to save human lives and reduce healthcare costs.