Synthesis of Isolated DNA Aptamer and Its Application of AC-Electrothermal Flow-Based Rapid Biosensor for the Detection of Dengue Virus in a Spiked Sample.

Dengue fever is an infectious disease caused by the dengue virus (DENV) and is transmitted by mosquitoes in tropical and subtropical regions. The early detection method at a low cost is essential. To address this, we synthesized the isolated DENV aptamer for fabricating a rapid electrochemical biosensor on a Au interdigitated microgap electrode (AuIMGE). The DENV aptamers were generated using the SELEX (systemic evolution of ligands by exponential enrichment) method for binding to DENV surface envelope proteins. To reduce the manufacturing cost, unnecessary nucleotide sequences were excluded from the isolation process of the DENV aptamer. To reduce the detection time, the alternating current electrothermal flow (ACEF) technique was applied to the fabricated biosensor, which can shorten the detection time to 10 min. The performance of the biosensor was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the diluted DENV protein solution, the linear range of the concentrations was from 1 pM to 1 µM and the LOD was 76.7 fM. Moreover, the proposed biosensor detected DENV in a diluted spiked sample at a linear range of 10-6 to 106 TCID50/mL, while the detection performance was proven with an LOD of 1.74 × 10-7 TCID50/mL along with high selectivity.

Construction of a rapid electrochemical biosensor consisting of a nanozyme/aptamer conjugate for waterborne microcystin detection.

Microcystin-LR (MC-LR) is a hepatotoxin generated by the excessive proliferation of cyanobacteria, which is a threat to humans and wildlife. Therefore, rapid detection of MC-LR is an important challenge. This study describes a rapid electrochemical biosensor comprising nanozymes and aptamers. Alternating current electrothermal flow (ACEF) significantly reduced the MC-LR detection period to 10 min. We also used MnO2/MC-LR aptamer conjugates to improve the sensitivity to MC-LR detection. Here, MnO2 amplified the electrochemical signal and the aptamer showed high selectivity for MC-LR. Under the optimal conditions, the limit of detection (LOD) and selectivity in freshwater were detected using cyclic voltammetry and differential pulse voltammetry. As a result, an LOD of 3.36 pg mL-1 was observed in the linear concentration range of 10 pg mL-1 to 1 µg mL-1. This study quickly and sensitively detected MC-LR in a situation where it causes serious damage worldwide. In addition, the ACEF technology introduction is the first example of MC-LR detection, suggesting a wide range of possibilities for MC-LR biosensors.

Scaffold-induced compression enhances ligamentization potential of decellularized tendon graft reseeded with ACL-derived cells.

Anterior cruciate ligament (ACL) reconstruction is often performed using a tendon graft. However, the predominant synthesis of fibrotic scar tissue (type III collagen) occurs during the healing process of the tendon graft, resulting in a significantly lower mechanical strength than that of normal ACL tissue. In this study, ACL-derived cells were reseeded to the tendon graft, and scaffold-induced compression was applied to test whether the compressive force results in superior cell survival and integration. Given nanofiber polycaprolactone (PCL) scaffold-induced compression, ACL-derived cells reseeded to a tendon graft demonstrated superior cell survival and integration and resulted in higher gene expression levels of type I collagen compared to non-compressed cell-allograft composites in vitro. Translocation of Yes-associated protein (YAP) into the nucleus was correlated with higher expression of type I collagen in the compression group. These data support the hypothesis of a potential role of mechanotransduction in the ligamentization process.

Recent Advances in DNA Nanotechnology for Plasmonic Biosensor Construction.

Since 2010, DNA nanotechnology has advanced rapidly, helping overcome limitations in the use of DNA solely as genetic material. DNA nanotechnology has thus helped develop a new method for the construction of biosensors. Among bioprobe materials for biosensors, nucleic acids have shown several advantages. First, it has a complementary sequence for hybridizing the target gene. Second, DNA has various functionalities, such as DNAzymes, DNA junctions or aptamers, because of its unique folded structures with specific sequences. Third, functional groups, such as thiols, amines, or other fluorophores, can easily be introduced into DNA at the 5' or 3' end. Finally, DNA can easily be tailored by making junctions or origami structures; these unique structures extend the DNA arm and create a multi-functional bioprobe. Meanwhile, nanomaterials have also been used to advance plasmonic biosensor technologies. Nanomaterials provide various biosensing platforms with high sensitivity and selectivity. Several plasmonic biosensor types have been fabricated, such as surface plasmons, and Raman-based or metal-enhanced biosensors. Introducing DNA nanotechnology to plasmonic biosensors has brought in sight new horizons in the fields of biosensors and nanobiotechnology. This review discusses the recent progress of DNA nanotechnology-based plasmonic biosensors.

Electrochemical biosensor with aptamer/porous platinum nanoparticle on round-type micro-gap electrode for saxitoxin detection in fresh water.

Cyanotoxins are toxins produced by cyanobacteria; they negatively impact water resources used by humans and disrupt ecosystems worldwide. Among cyanotoxins, saxitoxin (STX) is a small molecule that causes paralysis in humans and contamination in freshwater resources. To monitor low concentration of STX levels, a sensitive and high fidelity detection system is required. In this study, a round-type micro-gap electrode (RMGE) was fabricated that provides the high signal fidelity for STX detection in real freshwater sample. The RMGE has the 15 pairs of identical electrode wire length between gap that gives the high signal fidelity. In addition, the sensitivity for STX detection was improved by introducing the porous platinum nanoparticle (pPtNP) that enahced the electrochemical sensitivity and the STX aptamer was used as the bioprobe. An electrochemical measurement method (square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS)) was introduced to construct STX biosensor. To evaluate the biosensor performance, the limit of detection (LOD) and selectivity test were performed on real freshwater samples. The biosensor demonstrated high selectivity even in freshwater samples over a wide linear concentration range of 10 pg/mL to 1 µg/mL and a detection limit of 4.669 pg/mL. These results suggest that the designed biosensor shows a wide range of possibilities for the detection of toxicants in freshwater that provide the new direction to the biosensor electrode design.

Protective Effect of Human-Neural-Crest-Derived Nasal Turbinate Stem Cells against Amyloid-ß Neurotoxicity through Inhibition of Osteopontin in a Human Cerebral Organoid Model of Alzheimer's Disease.

The aim of this study was to validate the use of human brain organoids (hBOs) to investigate the therapeutic potential and mechanism of human-neural-crest-derived nasal turbinate stem cells (hNTSCs) in models of Alzheimer's disease (AD). We generated hBOs from human induced pluripotent stem cells, investigated their characteristics according to neuronal markers and electrophysiological features, and then evaluated the protective effect of hNTSCs against amyloid-ß peptide (Aß1-42) neurotoxic activity in vitro in hBOs and in vivo in a mouse model of AD. Treatment of hBOs with Aß1-42 induced neuronal cell death concomitant with decreased expression of neuronal markers, which was suppressed by hNTSCs cocultured under Aß1-42 exposure. Cytokine array showed a significantly decreased level of osteopontin (OPN) in hBOs with hNTSC coculture compared with hBOs only in the presence of Aß1-42. Silencing OPN via siRNA suppressed Aß-induced neuronal cell death in cell culture. Notably, compared with PBS, hNTSC transplantation significantly enhanced performance on the Morris water maze, with reduced levels of OPN after transplantation in a mouse model of AD. These findings reveal that hBO models are useful to evaluate the therapeutic effect and mechanism of stem cells for application in treating AD.

Recent Advances in Aptasensor for Cytokine Detection: A Review.

Cytokines are proteins secreted by immune cells. They promote cell signal transduction and are involved in cell replication, death, and recovery. Cytokines are immune modulators, but their excessive secretion causes uncontrolled inflammation that attacks normal cells. Considering the properties of cytokines, monitoring the secretion of cytokines in vivo is of great value for medical and biological research. In this review, we offer a report on recent studies for cytokine detection, especially studies on aptasensors using aptamers. Aptamers are single strand nucleic acids that form a stable three-dimensional structure and have been receiving attention due to various characteristics such as simple production methods, low molecular weight, and ease of modification while performing a physiological role similar to antibodies.

Fabrication of an electrochemical biosensor composed of multi-functional Ag ion intercalated DNA four-way junctions/rhodium nanoplate heterolayer on a micro-gap for C-reactive protein detection in human serum.

As inflammation plays a role in the pathogenesis of acute coronary syndromes, C-reactive protein (CRP) can be used as a biomarker. To detect CRP precisely, the authors prepared a CRP electrochemical biosensor consisting of an eight Ag ion-intercalated multifunctional DNA four-way junction (MF-DNA-4WJ) and a porous rhodium nanoparticle (pRhNP) heterolayer on a micro-gap electrode. To increase conductivity, we used eight Ag+ ion-inserted DNA four-way junctions through a C-C mismatch. Each DNA 4WJ was designed to have the CRP aptamer sequence, an anchoring region (thiol group), and two of four C-C mismatch regions at the end of the fragments. After an annealing step, the MF-DNA-4WJ assembly configuration and selective binding of CRP were confirmed through native TBM-PAGE (Tris-borate-magnesium chloride-polyacrylamide gel electrophoresis). The Au micro-gap electrode was fabricated to load 5 µl of the sample, and this was performed during eight experiments on one chip to establish the accuracy of the data. Then, pRhNPs were immobilized on a Au micro-gap electrode using cysteamine. To confirm the electrochemical properties, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted. The durability of pRhNPs was confirmed through CV. To test the sensing performance of the prepared CRP biosensor, the limit of detection (LOD) and selectivity tests were conducted using EIS. The results indicated that charge transfer resistance (Rct) can be used efficiently to probe these interactions within the variable CRP concentration range, from 1 pM to 100 nM (0.23 ng L-1-23 µg L-1). The LOD of this sensor was 0.349 pM (0.08 ng L-1) (at S/N = 3). As a result of diluting the CRP to the same concentration range in a 20% human serum sample, the LOD was 3.55 fM (0.814 pg L-1) (at S/N = 3).

Fabrication of Electrochemical Influenza Virus (H1N1) Biosensor Composed of Multifunctional DNA Four-Way Junction and Molybdenum Disulfide Hybrid Material.

The outbreak of the influenza virus (H1N1) has symptoms such as coughing, fever, and a sore throat, and due to its high contagious power, it is fatal to humans. To detect H1N1 precisely, the present study proposed an electrochemical biosensor composed of a multifunctional DNA four-way junction (4WJ) and carboxyl molybdenum disulfide (carboxyl-MoS2) hybrid material. The DNA 4WJ was constructed to have the hemagglutinin aptamer on the head group (recognition part); each of the two arms has four silver ions (signal amplification part), and the tail group has an amine group (anchor). This fabricated multifunctional DNA 4WJ can specifically and selectively bind to hemagglutinin. Moreover, the carboxyl-MoS2 provides an increase in the sensitivity of this biosensor. Carboxyl-MoS2 was immobilized using a linker on the electrode, followed by the immobilization of the multifunctional 4WJ on the electrode. The synthesis of carboxyl-MoS2 was confirmed by field emission scanning electron microscopy (FE-SEM), and the surface of the electrode was confirmed by atomic force microscopy. When H1N1 was placed in the immobilized electrode, the presence of H1N1 was confirmed by electrochemical analysis (cyclic voltammetry, electrochemical impedance spectroscopy). Through selectivity tests, it was also possible to determine whether this sensor responds specifically and selectively to H1N1. We confirmed that the biosensor showed a linear response to H1N1, and that H1N1 could be detected from 100 nM to 10 pM. Finally, clinical tests, in which hemagglutinin was diluted with human serum, showed a similar tendency to those diluted with water. This study showed that the multi-functional DNA 4WJ and carboxyl-MoS2 hybrid material can be applied to a electrochemical H1N1 biosensor.

Development of yuja (Citrus junos) beverage based on antioxidant properties and sensory attributes using response surface methodology.

This study aimed to develop a new type of Citrus junos beverage (known as yuja in Korean and yuzu in Japanese) based on a traditional drink preparation method (Galsu). Processing conditions (yuja extract, sugar, and soybean milk) were optimized using response surface methodology (RSM) to develop the beverage. The polynomial models developed by RSM were based on physicochemical characteristics and sensory attributes. Sugar, vitamin C, and total phenolic compound contents, DPPH free radical scavenging activity, sweet odor, yuja flavor, sweet taste, and pungent sensation were used as indices of positive product quality. Beany flavor, astringent taste, beany aftertaste, and astringent aftertaste, were used as indices of negative product quality. Sour odor and sour taste, which are the major characteristics of the traditional yuja beverage, were set in a range to optimize the numerical model. The predicted optimum formulation of yuja beverage (Galsu) as a final product was determined to be 28.4% yuja extract, 36.6% sugar, and 35.0% soybean milk.

Improvement of induction remission rate by modifying the dose of idarubicin for relapsed childhood acute lymphoblastic leukemia.

Relapse is the major cause of treatment failure in acute lymphoblastic leukemia (ALL), yet there is no established treatment for relapsed ALL. To improve the induction remission rate, we modified the dose of idarubicin in the original Children's Cancer Group (CCG)-1884 protocol, and retrospectively compared the results. Twenty-eight patients diagnosed with relapsed ALL received induction chemotherapy according to the CCG-1884 protocol. Complete remission (CR) rate in all patients after induction chemotherapy was 57%. The idarubicin 10 mg/m(2)/week group showed CR rate of 74%, compared with the 22% CR rate of the idarubicin 12.5 mg/m(2)/week group (p=0.010). Remission failure due to treatment-related mortality (TRM) was 44% and 5.2% in the idarubicin 12.5 mg/m(2)/week and 10 mg/m(2)/week groups, respectively (p=0.011). Overall survival (OS) and 4-yr event-free survival (EFS) were 12.8% and 10.3%, respectively. OS and 4-yr EFS were higher in the idarubicin 10 mg/m(2)/week group (19.3% and 15.6%) than in the 12.5 mg/m(2)/week group (0% and 0%). In conclusion, a modified dose of idarubicin from 12.5 mg/m(2)/week to 10 mg/m(2)/week resulted in an improved CR rate in the treatment of relapsed ALL, which was due to lower TRM. However, despite improved CR rate with modified dose of idarubicin, survival rates were unsatisfactory.

Unrelated bone marrow transplantation with a reduced toxicity myeloablative conditioning regimen in Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is an X-linked congenital immune-deficiency syndrome, and bone marrow transplantation (BMT) has become a curative modality. However, the transplant with the alternative donor needed more intensive conditioning with increased treatment-related toxicities. Recently, fludarabine-based reduced toxicity myeloablative conditioning regimens have been developed for adult myeloid malignancies with promising results of good engraftment and low treatment-related toxicities. To increase the engraftment potential without serious complications, a boy with WAS received successful unrelated BMT with a reduced toxicity myeloablative conditioning regimen composed of fludarabine (40 mg/m2) on days -8, -7, -6, -5, -4, -3), busulfan (0.8 mg/kg i. v. q 6 hr on days -6, -5, -4, -3), and thymoglobulin (2.5 mg/kg on days -4, -3, -2). This novel conditioning regimen could improve the outcome of allogeneic transplantation for other non-malignant diseases such as congenital immune-deficiency syndromes or metabolic storage diseases.

Retrospective analysis of peripheral blood stem cell transplantation for the treatment of high-risk neuroblastoma.

Disease relapse after autologous peripheral blood stem cell transplantation (APBSCT) is the main cause of treatment failure in high-risk neuroblastoma (NBL). To reduce relapse, various efforts have been made such as CD34+ selection and double APBSCT. Here the authors reviewed the clinical features and outcomes of highrisk NBL patients and analyzed their survival. The medical records of 36 patients with stage III or IV NBL who underwent APBSCT at Seoul National University Children's Hospital between May 1996 and May 2004 were reviewed. Total 46 APBSCTs were performed in 36 patients. Disease free survival (DFS) and overall survival of all patients were 47.7% and 68.8%, respectively. The patients were allocated to three groups according to the APBSCT type. The DFS of CD34+ non-selected single APBSCT patients (N=13), CD34+ selected single APBSCT patients (N=14), and CD34+ selected double APBSCT patients (N=9) were 55.6%, 40.6%, and 50.0%, respectively, which were not significantly different. Thus the survival was not found to be affected by CD34+ selection or transplantation number. To improve long-term survival, various efforts should be made such as chemotherapy dose intensification, more effective tumor purging, and control of minimal residual disease via the use of differentiating and immune-modulating agents.

hKv1.5 channels play a pivotal role in the functions of human alveolar macrophages.

We examined the pharmacological properties, the molecular identity, and the functional roles of hKv1.5 channel in human alveolar macrophage. Some of outward K(+) current was inhibited by 4-aminopyridine and antisense oligodeoxynucleotides against hKv1.5 mRNA. Consistently, the protein and mRNA expressions of hKv1.5 channel were detected. Furthermore, the phagocytosis and migration of human alveolar macrophages were significantly suppressed when the protein expression of hKv1.5 channel was lowered by the antisense hKv1.5 oligodeoxynucleotides. These results suggest that hKv1.5 channel is expressed in human alveolar macrophages and it plays a role in phagocytosis and migration of the human alveolar macrophage.

Polymorphism of matrix metalloproteinase-3 promoter gene as a risk factor for coronary artery lesions in Kawasaki disease.

Kawasaki disease (KD) is a major cause of acquired coronary artery diseases in childhood. The serum levels of matrix metalloproteinase (MMP)-3 and MMP-9 in KD have been reported to be significantly higher than other diseases. Several studies have demonstrated that MMP-3 5A/6A polymorphism and MMP-9 C-1562T polymorphism modify each transcriptional activity in allele specific manner. We hypothesized that these polymorphisms may play a role as a risk factor for development of coronary artery lesions (CAL) in KD. Eighty-three patients, diagnosed with KD in Cheju National University Hospital from January 2000 to February 2004, were divided into two groups according to the presence of CAL. Genotyping of MMP-3 and MMP-9 gene polymorphisms were determined by restriction fragment length polymorphism. With regard to MMP-3 gene polymorphism, the KD with CAL group had a higher frequency of 6A/6A genotype than control group (p=0.0127) and the KD without CAL group (p=0.0036). However, no significant differences in the allele and genotype distributions of the MMP-9 polymorphism were observed. These findings suggest that MMP-3 6A/6A genotype may be an independent risk factor for CAL formation in KD.

Identification and antibacterial activity of a new oleandomycin derivative from Streptomyces antibioticus.

During the study on the oleandomycin production, we purified a new oleandomycin derivative having a macrolactone of which biosynthesis does not follow the genetic architecture of the oleandomycin PKS. The molecular formula for the compound was suggested as C35H59NO11 on the basis of the analysis of NMR and HRMS data (m/z 670.4185, Delta-1.9mmu, calcd for C35H60NO11). 13C NMR assignments and analysis of COSY, HMBC and HMQC data suggested that the compound differs from oleandomycin by formation of the olefinic functionality resulting from the dehydration of a hydroxy group in oleandomycin. The new oleandomycin derivative has antibacterial activities similar to those of oleandomycin agaisnt Enterococcus faecalis, Bacillus subtilis and Staphylococcus aureus.

Open channel block of hKv1.5 by psoralen from Heracleum moellendorffii Hance.

A furocoumarin derivative, psoralen (7H-furo[3,2-g][1]benzopyran-7-one), was isolated from the n-hexane fraction of Heracleum moellendorffii Hance. We examined the effects of psoralen on a human Kv1.5 potassium channel (hKv1.5) cloned from human heart and stably expressed in Ltk- cells. We found that psoralen inhibited the hKv1.5 current in a concentration-, use- and voltage-dependent manner with an IC50 value of 180 +/- 21 nM at +60 mV. Psoralen accelerated the inactivation kinetics of the hKv1.5 channel, and it slowed the deactivation kinetics of the hKv1.5 current resulting in a tail crossover phenomenon. These results indicate that psoralen acts on the hKv1.5 channel as an open channel blocker. Furthermore, psoralen prolonged the action potential duration of rat atrial muscles in a dose-dependent manner. Taken together, the present results strongly suggest that psoralen may be an ideal antiarrhythmic drug for atrial fibrillation.