Yong Shin

Two-stage sample-to-answer system based on nucleic acid amplification approach for detection of malaria parasites.

Rapid, early, and accurate diagnosis of malaria is essential for effective disease management and surveillance, and can reduce morbidity and mortality associated with the disease. Although significant advances have been achieved for the diagnosis of malaria, these technologies are still far from ideal, being time consuming, complex and poorly sensitive as well as requiring separate assays for sample processing and detection. Therefore, the development of a fast and sensitive method that can integrate sample processing with detection of malarial infection is desirable. Here, we report a two-stage sample-to-answer system based on nucleic acid amplification approach for detection of malaria parasites. It combines the Dimethyl adipimidate (DMA)/Thin film Sample processing (DTS) technique as a first stage and the Mach-Zehnder Interferometer-Isothermal solid-phase DNA Amplification (MZI-IDA) sensing technique as a second stage. The system can extract DNA from malarial parasites using DTS technique in a closed system, not only reducing sample loss and contamination, but also facilitating the multiplexed malarial DNA detection using the fast and accurate MZI-IDA technique. Here, we demonstrated that this system can deliver results within 60min (including sample processing, amplification and detection) with high sensitivity (<1 parasite μL(-1)) in a label-free and real-time manner. The developed system would be of great potential for better diagnosis of malaria in low-resource settings.

Eu, Gd-Codoped Yttria Nanoprobes for Optical and T1-Weighted Magnetic Resonance Imaging

Nanoprobes with multimodal functionality have attracted significant interest recently because of their potential applications in nanomedicine. This paper reports the successful development of lanthanide-doped Y2O3 nanoprobes for potential applications in optical and magnetic resonance (MR) imaging. The morphology, structural, and optical properties of these nanoprobes were characterized by transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and photoluminescence (PL). The cytotoxicity test showed that the prepared lanthanide-doped Y2O3 nanoprobes have good biocompatibility. The obvious contrast enhancement in the T1-weighted MR images suggested that these nanoprobes can be used as a positive contrast agent in MRI. In addition, the clear fluorescence images of the L-929 cells incubated with the nanoprobes highlight their potential for optical imaging. Overall, these results suggest that prepared lanthanide-doped Y2O3 nanoprobes can be used for simultaneous optical and MR imaging.

The Effect of Reduced Graphene Oxide-Coated Biphasic Calcium Phosphate Bone Graft Material on Osteogenesis

This study was conducted to evaluate the effect of biphasic calcium phosphate (BCP) coated with reduced graphene oxide (rGO) as bone graft materials on bone regeneration. The rGO-coated BCP bone graft material was fabricatied by mixing rGO and BCP at various concentrations. The surface charge of rGO-coated BCP was measured to be −14.43 mV, which formed a static electrostatic interaction. Cell viabilities were significantly diminished at higher concentrations of ≥100 μg/mL. The calvarial defects of 48 rats were implanted rGO-coated BCPs at a weight ratio of 2:1000 (rGO2), 4:1000 (rGO4), and 10:1000 (rGO10), repectively. BCP was used as a control group. The micro-CT and histological analysis were performed to evaluate new bone formation at 2 and 8 weeks after surgery. The results showed that the new bone volume (mm3) was significantly higher in the experimental groups than in the control group. Histological analysis showed that new bone areas (%) were significantly higher in the rGO2 and rGO10 than in the control, and significantly higher in rGO4 than in the rGO2 and rGO10. Conclusively, the rGO-coated BCP was found to be effective on osteogenesis and the concentration of the composite was an important factor.

Toxicity and T2-Weighted Magnetic Resonance Imaging Potentials of Holmium Oxide Nanoparticles

In recent years, paramagnetic nanoparticles (NPs) have been widely used for magnetic resonance imaging (MRI). This paper reports the fabrication and toxicity evaluation of polyethylene glycol (PEG)-functionalized holmium oxide (Ho2O3) NPs for potential T2-weighted MRI applications. Various characterization techniques were used to examine the morphology, structure and chemical properties of the prepared PEG–Ho2O3 NPs. MRI relaxivity measurements revealed that PEG–Ho2O3 NPs could generate a strong negative contrast in T2-weighted MRI. The pilot cytotoxicity experiments showed that the prepared PEG–Ho2O3 NPs are biocompatible at concentrations less than 16 μg/mL. Overall, the prepared PEG–Ho2O3 NPs have potential applications for T2-weighted MRI imaging.

An isothermal, label-free, and rapid one-step RNA amplification/detection assay for diagnosis of respiratory viral infections.

n Abstractn n Recently, RNA viral infections caused by respiratory viruses, such as influenza, parainfluenza, respiratory syncytial virus, coronavirus, and Middle East respiratory syndrome-coronavirus (MERS-CoV), and Zika virus, are a major public health threats in the world. Although myriads of diagnostic methods based on RNA amplification have been developed in the last decades, they continue to lack speed, sensitivity, and specificity for clinical use. A rapid and accurate diagnostic method is needed for appropriate control, including isolation and treatment of the patients. Here, we report an isothermal, label-free, one-step RNA amplification and detection system, termed as iROAD, for the diagnosis of respiratory diseases. It couples a one-step isothermal RNA amplification method and a bio-optical sensor for simultaneous viral RNA amplification/detection in a label-free and real-time manner. The iROAD assay offers a one-step viral RNA amplification/detection example to rapid analysis (<20min). The detection limit of iROAD assay was found to be 10-times more sensitive than that of real-time reverse transcription-PCR method. We confirmed the clinical utility of the iROAD assay by detecting viral RNAs obtained from 63 human respiratory samples. We envision that the iROAD assay will be useful and potentially adaptable for better diagnosis of emerging infectious diseases including respiratory diseases.n n

Multifaceted Biomedical Applications of Functional Graphene Nanomaterials to Coated Substrates, Patterned Arrays and Hybrid Scaffolds

Because of recent research advances in nanoscience and nanotechnology, there has been a growing interest in functional nanomaterials for biomedical applications, such as tissue engineering scaffolds, biosensors, bioimaging agents and drug delivery carriers. Among a great number of promising candidates, graphene and its derivatives—including graphene oxide and reduced graphene oxide—have particularly attracted plenty of attention from researchers as novel nanobiomaterials. Graphene and its derivatives, two-dimensional nanomaterials, have been found to have outstanding biocompatibility and biofunctionality as well as exceptional mechanical strength, electrical conductivity and thermal stability. Therefore, tremendous studies have been devoted to employ functional graphene nanomaterials in biomedical applications. Herein, we focus on the biological potentials of functional graphene nanomaterials and summarize some of major literature concerning the multifaceted biomedical applications of functional graphene nanomaterials to coated substrates, patterned arrays and hybrid scaffolds that have been reported in recent years.

Dose- and Time-Dependent Cytotoxicity of Layered Black Phosphorus in Fibroblastic Cells

Black phosphorus (BP) is a monolayer/multilayer two-dimensional (2D) nanomaterial, which has recently emerged as one of the most attractive 2D nanomaterials due to its fascinating physicochemical and optoelectronical properties. Layered BP may have promising applications in biomedical fields, such as drug delivery, photodynamic/photothermal therapy and bioimaging, although its intrinsic toxicity has not been fully elucidated yet. In the present study, the cytotoxicological effects of layered BP on both cell metabolic activity and membrane integrity were investigated. Layered BPs were prepared using a modified ultrasonication-assisted solution method, and their physicochemical properties were characterized. The dose- and time-dependent cytotoxicity of layered BP was assessed against L-929 fibroblasts. Our findings indicate that the cytotoxicity of BPs is proportionally dependent on their concentration and exposure time, which is affected by the oxidative stress-mediated enzyme activity reduction and membrane disruption. On the other hand, layered BPs did not exhibit significant cytotoxicity at concentrations lower than 4 μg/mL. Therefore, it is suggested that layered BPs can be effectively utilized as therapeutic delivery carriers and imaging agents.

Molecular epidemiology and environmental contamination during an outbreak of parainfluenza virus 3 in a haematology ward

n Summaryn n Backgroundn Although fomites or contaminated surfaces have been considered as transmission routes, the role of environmental contamination by human parainfluenza virus type 3 (hPIV-3) in healthcare settings is not established.n n n Aimn To describe an hPIV-3 nosocomial outbreak and the results of environmental sampling to elucidate the source of nosocomial transmission and the role of environmental contamination.n n n Methodsn During an hPIV-3 outbreak between May and June 2016, environmental surfaces in contact with clustered patients were swabbed and respiratory specimens used from infected patients and epidemiologically unlinked controls. The epidemiologic relatedness of hPIV-3 strains was investigated by sequencing of the haemagglutinin–neuraminidase and fusion protein genes.n n n Findingsn Of 19 hPIV-3-infected patients, eight were haematopoietic stem cell recipients and one was a healthcare worker. In addition, four had upper and 12 had lower respiratory tract infections. Of the 19 patients, six (32%) were community-onset infections (symptom onset within <7 days of hospitalization) and 13 (68%) were hospital-onset infections (≥7 days of hospitalization). Phylogenetic analysis identified two major clusters: five patients, and three patients plus one healthcare worker. Therefore, seven (37%) were classified as nosocomial transmissions. hPIV-3 was detected in 21 (43%) of 49 environmental swabs up to 12 days after negative respiratory polymerase chain reaction conversion.n n n Conclusionn At least one-third of a peak season nosocomial hPIV-3 outbreak originated from nosocomial transmission, with multiple importations of hPIV-3 from the community, providing experimental evidence for extensive environmental hPIV-3 contamination. Direct contact with the contaminated surfaces and fomites or indirect transmission from infected healthcare workers could be responsible for nosocomial transmission.n n

Rapid Diagnosis of Tick-Borne Illnesses by Use of One-Step Isothermal Nucleic Acid Amplification and Bio-Optical Sensor Detection

BACKGROUNDnScrub typhus and severe fever with thrombocytopenia syndrome (SFTS) are the most common tick-borne illnesses in South Korea. Early differentiation of SFTS from scrub typhus in emergency departments is essential but difficult because of their overlapping epidemiology, shared risk factors, and similar clinical manifestations.nnnMETHODSnWe compared the diagnostic performance of one-step isothermal nucleic acid amplification with bio-optical sensor detection (iNAD) under isothermal conditions, which is rapid (20-30 min), with that of real-time PCR, in patients with a confirmed tick-borne illness. Fifteen patients with confirmed SFTS who provided a total of 15 initial blood samples and 5 follow-up blood samples, and 21 patients with confirmed scrub typhus, were evaluated.nnnRESULTSnThe clinical sensitivity of iNAD (100%; 95% CI, 83-100) for SFTS was significantly higher than that of real-time PCR (75%; 95% CI, 51-91; P = 0.047), while its clinical specificity (86%; 95% CI, 65-97) was similar to that of real-time PCR (95%; 95% CI, 77-99; P = 0.61). The clinical sensitivity of iNAD for scrub typhus (100%; 95% CI, 81-100) was significantly higher than that of real-time PCR for scrub typhus (67%; 95% CI, 43-85; P = 0.009), while its clinical specificity (90%; 95% CI, 67-98) was similar to that of real-time PCR (95%; 95% CI, 73-100; P > 0.99).nnnCONCLUSIONSniNAD is a valuable, rapid method of detecting SFTS virus and Orientia tsutsugamushi with high clinical sensitivity and specificity.

Use of Dimethyl Pimelimidate with Microfluidic System for Nucleic Acids Extraction without Electricity

The isolation of nucleic acids in the lab on a chip is crucial to achieve the maximal effectiveness of point-of-care testing for detection in clinical applications. Here, we report on the use of a simple and versatile single-channel microfluidic platform that combines dimethyl pimelimidate (DMP) for nucleic acids (both RNA and DNA) extraction without electricity using a thin-film system. The system is based on the adaption of DMP into nonchaotropic-based nucleic acids and the capture of reagents into a low-cost thin-film platform for use as a microfluidic total analysis system, which can be utilized for sample processing in clinical diagnostics. Moreover, we assessed the use of the DMP system for the extraction of nucleic acids from various samples, including mammalian cells, bacterial cells, and viruses from human disease, and we also confirmed that the quality and quantity of the nucleic acids extracted were sufficient to allow for the robust detection of biomarkers and/or pathogens in downstream analysis. Furthermore, this DMP system does not require any instruments and electricity, and has improved time efficiency, portability, and affordability. Thus, we believe that the DMP system may change the paradigm of sample processing in clinical diagnostics.