Small-angle neutron scattering measurement of silicon nanoparticle size

Size characterization of nanomaterials in environmental and biological matrices through non-electron microscopic techniques

Engineered nanomaterials (ENs) can enter the environment, and accumulate in food chains, thereby causing environmental and health problems. Size characterization of ENs is critical for further evaluating the interactions among ENs in biological and ecological systems. Although electron microscope is a powerful tool in obtaining the size information, it has limitations when studying nanomaterials in complex matrices. In this review, we summarized non-electron microscope-based techniques, including chromatography-based, mass spectrometry-based, synchrotron radiation- and neutron-based techniques for detecting the size of ENs in environmental and biological matrices. The advantages and disadvantages of these techniques were highlighted. The perspectives on size characterization of ENs in complex matrices were also presented.

Stability of Engineered Micro or Nanobubbles for Biomedical Applications

A micro/nanobubble (MNB) refers to a bubble structure sized in a micrometer or nanometer scale, in which the core is separated from the external environment and is normally made of gas. Recently, it has been confirmed that MNBs can be widely used in angiography, drug delivery, and treatment. Thus, MNBs are attracting attention as they are capable of constructing a new contrast agent or drug delivery system. Additionally, in order to effectively use an MNB, the method of securing its stability is also being studied. This review highlights the factors affecting the stability of an MNB and the stability of the MNB within the ultrasonic field. It also discusses the relationship between the stability of the bubble and its applicability in vivo.

Development of Antibiofilm Nanocomposites: Ag/Cu Bimetallic Nanoparticles Synthesized on the Surface of Graphene Oxide Nanosheets

There are numerous issues associated with bacteria, particularly biofilms, which exhibit a strong resistance to antibiotics. This is currently considered an urgent global issue owing to the lack of effective treatments. Graphene oxide (GO) nanosheets are two-dimensional carbon materials that are available as a substrate for metal nanoparticles and have a lower release rate of metal ions than free metal nanoparticles by regulating the oxidation of metal nanoparticles, which is known to reduce the cytotoxicity caused by the free metal nanoparticles. Over centuries, metal particles, including Ag and Cu, have been considered as antibacterial agents. In this study, Ag and Cu bimetallic nanoparticles on a GO surface (Ag/Cu/GO) were synthesized using a chemical reduction method, and their antimicrobial effects against several bacterial species were demonstrated. Ag/Cu/GO nanocomposites were characterized by transmission electron microscopy and energy-dispersive X-ray spectroscopy. The in vitro cytotoxicity of an Ag/Cu/GO nanocomposite was evaluated in human dermal fibroblasts, and its antibacterial activity against Methylobacterium spp., Sphingomonas spp., and Pseudomonas aeruginosa (P. aeruginosa) was also tested. The synthesized Ag/Cu/GO nanocomposite was able to eradicate all three bacterial species at a concentration that was harmless to human cells. In addition, Ag/Cu/GO successfully removed a biofilm originated from the culturing of P. aeruginosa in a microchannel with a dynamic flow. In a small-animal model, a biofilm-infected skin wound was healed quickly and efficiently by the topical application of Ag/Cu/GO. The Ag/Cu/GO nanocomposites reported in this study could be used to effectively remove antibiotic-resistant bacteria and treat diseases in the skin or wound due to bacterial infections and biofilm formation.

Anti-Tumor Drug-Loaded Oxygen Nanobubbles for the Degradation of HIF-1α and the Upregulation of Reactive Oxygen Species in Tumor Cells

Hypoxia is a key concern during the treatment of tumors, and hypoxia-inducible factor 1 alpha (HIF-1α) has been associated with increased tumor resistance to therapeutic modalities. In this study, doxorubicin-loaded oxygen nanobubbles (Dox/ONBs) were synthesized, and the effectiveness of drug delivery to MDA-MB-231 breast cancer and HeLa cells was evaluated. Dox/ONBs were characterized using optical and fluorescence microscopy, and size measurements were performed through nanoparticle tracking analysis (NTA). The working mechanism of Dox was evaluated using reactive oxygen species (ROS) assays, and cellular penetration was assessed with confocal microscopy. Hypoxic conditions were established to assess the effect of Dox/ONBs under hypoxic conditions compared with normoxic conditions. Our results indicate that Dox/ONBs are effective for drug delivery, enhancing oxygen levels, and ROS generation in tumor-derived cell lines.

Biological Responses of Onion-Shaped Carbon Nanoparticles

Nanodiamonds are emerging as new nanoscale materials because of their chemical stability, excellent crystallinity, and unique optical properties. In this study, the structure of nanodiamonds was engineered to produce carbon nano-onion particles (CNOs) with multiple layers. Following a series of physicochemical characterizations of the CNOs, various evaluations for biological responses were conducted for potential biotechnological applications of the CNOs. The possibility of biological applications was first confirmed by assessment of toxicity to animal cells, evaluation of hemolysis reactions, and evaluation of reactive oxygen species. In addition, human immune cells were evaluated for any possible induction of an immune response by CNOs. Finally, the toxicity of CNOs to Escherichia coli present in the human colon was evaluated. CNOs have the chemical and physical properties to be a unique variety of carbon nanomaterials, and their toxicity to animal and human cells is sufficiently low that their biotechnological applications in the future are expected.

Quantification of Unknown Nanoscale Biomolecules Using the Average-Weight-Difference Method

In order to quantify the amount of drug molecules in drug delivery systems, analytical techniques such as high-performance liquid chromatography are used due to their accuracy and reliability. However, the instruments required for such techniques are expensive and not available in all laboratories. Therefore, in this study, we introduce a method that can be a relatively inexpensive and easy to perform drug analysis in almost any laboratory set-up. We have devised the “average-weight-difference method” within the limits of existing spectral analyses. By employing this method, we quantitatively analyzed the amount of isoniazid or doxorubicin molecules loaded onto β-glucan nanoparticles. This proved to be a relatively simple and reliable method and can be used to estimate the amount of nanoscale biomolecules before their analysis through expensive equipment in an environment where the instruments are not readily available.

Surface Composition and Preparation Method for Oxygen Nanobubbles for Drug Delivery and Ultrasound Imaging Applications

Phospholipids have been widely investigated for the preparation of liposomes, and micro and nanobubbles. They comprise biocompatible and biodegradable molecules and offer simple preparation with a variety of functions in diagnostic and therapeutic applications. Phospholipids require emulsifiers and surfactants to assemble in the form of bubbles. These surfactants determine the size, zeta potential, and other characteristics of particles. Polyethylene glycol (PEG) and its various derivatives have been employed by researchers to synthesize micro and nanobubbles. The stability of phospholipid-shelled nanobubbles has been reported by various researchers owing to the reduction of surface tension by surfactants in the shell. Nanobubbles have been employed to deliver oxygen to tissues and hypoxic cells. In this study, we investigated the effects of different ratios of phospholipids to PEG on the size, distribution, and characterization of oxygen nanobubbles (ONBs). ONBs were synthesized using a sonication technique. We analyzed and compared the sizes, numbers of generated particles, and zeta potentials of different compositions of ONBs using dynamic light scattering and nanoparticle tracking analysis. Then, we employed these oxygen nanobubbles to enhance the cellular microenvironment and cell viability. ONBs were also investigated for ultrasound imaging.