Jin-Ha Choi

Signal Enhancement of Silicon Nanowire-Based Biosensor for Detection of Matrix Metalloproteinase-2 Using DNA-Au Nanoparticle Complexes

Silicon nanowires have been used in the development of ultrasensitive biosensors or chemical sensors, which is originated in its high surface-to-volume ratio and function as field-effect transistor (FET). In this study, we developed an ultrasensitive DNA-gold (Au) nanoparticle complex-modified silicon nanowire field effect transistor (SiNW-FET) biosensor to detect matrix metalloproteinase-2 (MMP-2), which has been of particular interest as protein biomarker because of its relation to several important human diseases, through an enzymatic cleavage reaction of a specific peptide sequence (IPVSLRSG). SiNW patterns with a width of 100 nm and height of 100 nm were fabricated on a p-type silicon-on-insulator (SOI) wafer by electron-beam lithography. Next, negatively charged DNA-Au nanoparticle complexes coupled with the specific peptide (KKGGGGGG-IPVSLRSG-EEEEEE) were applied on the SiNWs to create a more sensitive system, which was then bound to aldehyde-functionalized SiNW. The enhanced negatively charged nanoparticle complexes by attached DNA were used to enhance the conductance change of the p-SiNW by MMP-2 cleavage reaction of the specific peptide. MMP-2 was successfully measured within a range of 100 fM to 10 nM, and the conductance signal of the p-type SiNW by the MMP-2 cleavage reaction was enhanced over 10-fold by using the DNA-Au nanoparticle complexes compared with using SiNW-attached negative single peptide sequences.

Human gut-on-a-chip technology: will this revolutionize our understanding of IBD and future treatments?

Inflammatory bowel disease (IBD), such as ulcerative colitis (UC) and Crohn’s disease (CD), is the devastating chronic inflammation in human intestine, but the exact etiology is largely unknown [1]. Aberrant immune response to the commensal microbiota is supposed to be a leading cause, but other factors including genetic susceptibility, ‘leaky’ epithelial barrier, impaired bowel movement, and environmental factors (diet, stress, or smoking) are all thought to contribute to the IBD development [2]. Due to the multifactorial nature of IBD pathogenesis, it has been difficult to accurately pinpoint which contributing factor plays a key role in developing the IBD, and how multiple factors combinatorially interact to exacerbate the pathological symptoms. Thus, it is of great importance to develop an IBD model that can reconstitute the threedimensional (3D) structure of human intestine; recapitulate the pathophysiological cross talk between interacting factors; and respond to the chemical, biological, and physical interventions.

Priming nanoparticle-guided diagnostics and therapeutics towards human organs-on-chips microphysiological system

Nanotechnology and bioengineering have converged over the past decades, by which the application of multi-functional nanoparticles (NPs) has been emerged in clinical and biomedical fields. The NPs primed to detect disease-specific biomarkers or to deliver biopharmaceutical compounds have beena validated in conventional in vitro culture models including two dimensional (2D) cell cultures or 3D organoid models. However, a lack of experimental models that have strong human physiological relevance has hampered accurate validation of the safety and functionality of NPs. Alternatively, biomimetic human “Organs-on-Chips” microphysiological systems have recapitulated the mechanically dynamic 3D tissue interface of human organ microenvironment, in which the transport, cytotoxicity, biocompatibility, and therapeutic efficacy of NPs and their conjugates may be more accurately validated. Finally, integration of NP-guided diagnostic detection and targeted nanotherapeutics in conjunction with human organs-on-chips can provide a novel avenue to accelerate the NP-based drug development process as well as the rapid detection of cellular secretomes associated with pathophysiological processes.

Effective bioremediation of Cadmium (II), nickel (II), and chromium (VI) in a marine environment by using Desulfovibrio desulfuricans

Sulfate-reducing bacteria play a significant role in the bioremediation of heavy metal-contaminated water. In this study, we report an effective removal method for Cd, Ni, and Cr from a marine environment by using Desulfovibrio desulfuricans, which is a sulfate-reducing bacterium. D. desulfuricans showed stable growth characteristics in highly salinated water, and a strong resistance to these heavy metals. When attempting to drastically increase the removal ratio, the addition of ferrous ion with SO42− was found to be important for the removal of heavy metals from the salinated medium. In addition, the heavy metals tended to be more effectively removed from the medium at 37°C. In the case of heavy metals, 99.9, 98.3, and 74.2% of the Cd, Ni, and Cr, respectively, were effectively removed when present at 100 ppm concentration.

Nanomaterial-based in vitro analytical system for diagnosis and therapy in microfluidic device

Nanomaterials have several advantages in detecting several biomaterials and in enhancing signals and their inherent effects. Thus, they have been widely applied in the biomedical fields such as biosensor and cancer therapeutics. Recently, the development of microfluidic technology has led to superior biological analysis systems to detect biomarkers related to diseases or serve as in vitro drug screening platform. In a microfluidic device, samples could be analyzed more accurately, rapidly and simply. In addition, it is possible to culture the cells in these microfluidic devices, therefore making the in situ analysis of secretomes easy. Nanomaterials can be easily applied in the microfluidic channels as capturing and signaling materials in order to improve the sensing or therapeutic property. In particular, nanomaterial integrated microfluidic cell culture model can replace in vivo disease models for nanotherapeutics screening. In this review, nanomaterial-based sensing systems, which include diverse organic and inorganic nanoparticles, are introduced with specific examples, including microfluidics integrated systems. Moreover, microfluidics derived nanomaterial analytic systems as in vitro 2 or 3-dimensional (2D or 3D) cell culture platform will be presented. We also highlight the future perspectives of the microfluidic-driven system as highly sensitive total analysis system with functional nanoparticles.

Enhancement of CH4-water mass transfer using methyl-modified mesoporous silica nanoparticles

Surface-modified mesoporous silica nanoparticle (MSN) with methyl groups was used to enhance the CH4-water volumetric mass transfer coefficient (kLa) and the solubility of CH4 in water. Two types of samples were tested: unmodified MSN and methyl-modified MSN. The mass transfer for each type of sample was measured every 20 s by gas chromatography. The results showed that the methyl-modified MSN, which have both hydrophobic and hydrophilic properties on the surface, exhibited higher CH4-water volumetric mass transfer coefficient and solubility in water. The dissolved concentrations of CH4 were enhanced by 10.7% and 27.8%, and the volumetric mass transfer coefficient were enhanced by 28.6% and 84.7%, respectively, by using unmodified MSN and methyl-modified MSN.

Electrochemical sensor for selective detection of norepinephrine using graphene sheets-gold nanoparticle complex modified electrode

Neural diseases, like Alzheimer’s (AD) and Parkinson’s (PD) are widely expanding portions of neurodegenerative diseases, are related to norepinephrine (NE) concentration with proportional correlation. However, quantification of NE is quite difficult because NE coexists with ascorbic acid (AA) and uric acid (UA), which interferes with detecting NE in biological fluid. We fabricated a multi-modified electrode with reduced graphene oxide sheets (GS) and gold nanoparticles (GNPs) for highly selective and sensitive detection of NE. Thus, GS-GNPs modified electrode could enhance the sensitivity for detection of NE, as well as highly sensitive manner with AA. Compared with recent studies, our newly developed sensor appears to have not only a wide detection range (0.2-10 μM), but also superior detection limit (200 nM) in presence of 2000 times higher concentration of AA.

Self-illuminative cascade-reaction-driven anticancer therapeutic cassettes made of cooperatively interactive nanocomplexes.

Therapeutic options based on near-infrared (NIR) wavelengths have attracted attention owing to in vivo lowest-background interventions and the development of several nano-architectures with localized surface plasmon resonance. Because of their limited tissue penetration, the clinical use of NIR light-driven treatments is not widespread; this technology is inapplicable to infection sites in the deeper areas of internal tissues. In this study, we demonstrate a self-illuminative therapeutic cassette able to exert anticancer effects via a series of enzymatic, chemical, and optical cooperative cascade reactions. It consists of (1) NIR-illuminative nanocomplexes and (2) NIR-sensitive therapeutic cassettes, which demonstrate a 60% chemically-induced killing effect in a prostate cancer model without external NIR irradiation. This technology can also be actively exploited as an imaging agent due to adaptation of a self-illuminating nanocomplex. Consequently, these novel therapeutic cassettes, which work not only as a powerful internal NIR stimulant, but also as a biological imaging platform, provide a new rational design concept for biomedical use.

Predictive evaluation for the preparation of a synthetic Y-shaped DNA nanostructure

With the advent of deoxyribonucleic acid (DNA) nanotechnology, the Y-shaped DNA nanostructure (Y-DNA) as a basic block was first created. Due to their characteristic selectivity and specificity, Y-DNA-based materials have been utilized in a variety of scientific fields including multiplexed nanobarcoding. Basically, the tripod DNA nanostructure was prepared by simple hybridization of three different single stranded DNA (ssDNA). Before the synthetic process, the optical densities (OD) of the three ssDNAs were measured to accurately estimate the concentration. Through repeated temperature fluctuations, three ssDNAs were hybridized into a Y-shaped block with both a central junction and three blunt ended arms. After the reaction, the ODs of the synthesized DNA products were measured and compared with the theoretical OD values calculated by a MATLAB program (‘matrix laboratory’) with different molar concentrations and volumes to predict the presence of Y-DNA. Simultaneously, the product was analyzed by agarose gel electrophoresis to confirm the YDNA structure. The measured ODs of the solutions with confirmed Y-DNA structures were close to the theoretical maximum OD values. This article provides means to help understand and prepare Y-DNA by performing OD measurements. It is highly expected that this guide will be an excellent starting point for structural DNA nanotechnology.