High-Frequency Interdigitated Array Electrode-Based Capacitive Biosensor for Protein Detection

Tuan Vu Quoc,Viet Nguyen Ngoc,Tung Thanh Bui,Chun-Ping Jen,Trinh Chu Duc 한국바이오칩학회 2019 BioChip Journal Vol.13 No.4

This paper reports a study on developing of a protein detection biochip based on interdigitated array electrodes (IDAEs) capacitive immunosensor. The protein after being preconcentrated in a detection region will be selectively captured and detected by the capacitive immunosensor. Using electrical impedance spectroscopy operated at high-frequency in the range of 100 kHz–1 MHz, the capacitance of the gold electrode is determined and the antibody surface modification steps can be also monitored. The experiment results show the capacitance changes in accordance with the adding biochemical layer on gold electrodes for each step of the antibody surface modification. In particular, the total impedance operated at 1 MHz frequency has been seen to change from 2.1 kΩ of bare chip (before antibody surface modification) to 8 kΩ after antibody surface modification process while the serial capacitance is recorded to reduce steadily from 450 pF to 55 pF. Also, the efficiency of protein chip was investigated by implementing the measurement of 10 µM BSA with and without preconcentration process. The measurement results have shown the sensitivity increasing significantly after the protein is preconcentrated in this chip. The results demonstrate high efficiency of protein detection can be achieved by operating high frequency capacitive measurement on IDAEs capacitive immunosensor.

Subacute thyroiditis after receiving the vaccine for COVID-19: a case report and literature review

Thanh Binh Vu,Dinh Toi Chu,Dinh Tuan Le,Thi Thuy Dieu Hoang,Philippe Gautret,Van Thuan Hoang 대한백신학회 2022 Clinical and Experimental Vaccine Research Vol.11 No.2

A 38-year-old female patient, with healthy history, was vaccinated with ChAdOx1 nCoV-19 (Astra Zeneca Cambridge, UK). Five days after the second injection, the patient presented headache, vertigo, then fatigue, nervousness, palpitations, shortness of breath, small amplitude tremors, and sweating episodes. Laboratory investigation revealed a suppressed thyroid-stimulating hormone (TSH), with elevated free thyroxine. However, the TSH receptor antibody and anti-thyroid peroxidase antibody were normal and thyroid-stimulating immunoglobulin negative. The patient was maintained on Metoprolol, and no specific treatment was added. After 3 months of following, the patient now feels comfortable. Our literature review found that 21 cases of subacute thyroiditis (SAT) following coronavirus disease 2019 (COVID-19) vaccines were reported. Most patients were young women who presented neck pain and systemic symptoms, with or without fever. These symptoms can appear as early (3 to 5 days), or later (1 month) after vaccination, regardless of vaccine type and mechanism of action. Laboratory tests showed decreased levels of TSH and elevated thyroid hormone. The mechanism of this event remains unknown. Further study is recommended to investigate the possible predisposing factors to developing SAT after receiving the COVID-19 vaccine.

An improvement of real-time polymerase chain reaction system based on probe modification is required for accurate detection of African swine fever virus in clinical samples in Vietnam

Tran Ha Thi Thanh,Dang Anh Kieu,Ly Duc Viet,Vu Hao Thi,Hoang Tuan Van,Nguyen Chinh Thi,Chu Nhu Thi,Nguyen Vinh The,Nguyen Huyen Thi,Truong Anh Duc,Pham Ngoc Thi,Dang Hoang Vu 아세아·태평양축산학회 2020 Animal Bioscience Vol.33 No.10

Objective: The rapid and reliable detection of the African swine fever virus (ASFV) plays an important role in emergency control and preventive measures of ASF. Some methods have been recommended by FAO/OIE to detect ASFV in clinical samples, including real-time polymerase chain reaction (PCR). However, mismatches in primer and probe binding regions may cause a false-negative result. Here, a slight modification in probe sequence has been conducted to improve the qualification of real-time PCR based on World Organization for Animal Health (OIE) protocol for accurate detection of ASFV in field samples in Vietnam. Methods: Seven positive confirmed samples (four samples have no mismatch, and three samples contained one mutation in probe binding sites) were used to establish novel real-time PCR with slightly modified probe (Y = C or T) in comparison with original probe recommended by OIE. Results: Both real-time PCRs using the OIE-recommended probe and novel modified probe can detect ASFV in clinical samples without mismatch in probe binding site. A high correlation of cycle quantification (Cq) values was observed in which Cq values obtained from both probes arranged from 22 to 25, suggesting that modified probe sequence does not impede the qualification of real-time PCR to detect ASFV in clinical samples. However, the samples with one mutation in probe binding sites were ASFV negative with OIE recommended probe but positive with our modified probe (Cq value ranked between 33.12-35.78). Conclusion: We demonstrated for the first time that a mismatch in probe binding regions caused a false negative result by OIE recommended real-time PCR, and a slightly modified probe is required to enhance the sensitivity and obtain an ASF accurate diagnosis in field samples in Vietnam.

The potential efficacy of the E2-subunit vaccine to protect pigs against different genotypes of classical swine fever virus circulating in Vietnam

Ha Thi Thanh Tran,Duc Anh Truong,Viet Duc Ly,Hao Thi Vu,Tuan Van Hoang,Chinh Thi Nguyen,Nhu Thi Chu,Vinh The Nguyen,Duyen Thuy Nguyen,Kohtaroh Miyazawa,Takehiro Kokuho,Hoang Vu Dang 대한백신학회 2020 Clinical and Experimental Vaccine Research Vol.9 No.1

Purpose: To date, many kinds of classical swine fever (CSF) vaccines have been developed to protect against this disease. However, the efficacy of these vaccines to protect the pig against field CSF strains needs to be considered, based on circulating strains of classical swine fever virus (CSFV). Materials and Methods: Recombinant E2-CSFV protein produced by baculovirus/insect cell system was analyzed by western blots and immunoperoxidase monolayer assay. The effect of CSFV-E2 subunit vaccines was evaluated in experimental pigs with three genotypes of CSFV challenge. Anti-E2 specific and neutralizing antibodies in experimental pigs were analyzed by blocking enzyme-linked immunosorbent assay and neutralization peroxidize-linked assay. Results: The data showed that CSFV VN91-E2 subunit vaccine provided clinical protection in pigs against three different genotypes of CSFV without noticeable clinical signs, symptoms, and mortality. In addition, no CSFV was isolated from the spleen of the vaccinated pigs. However, the unvaccinated pigs exhibited high clinical scores and the successful virus isolation from spleen. These results showed that the E2-specific and neutralizing antibodies induced by VN91-E2 antigen appeared at day 24 after first boost and a significant increase was observed at day 28 (p<0.01). This response reached a peak at day 35 and continued until day 63 when compared to controls. Importantly, VN91-E2 induced E2-specific and neutralizing antibodies protected experimental pigs against high virulence of CSFVs circulating in Vietnam, including genotype 1.1, 2.1, and 2.2. Conclusion: These findings also suggested that CSFV VN91-E2 subunit vaccine could be a promising vaccine candidate for the control and prevention of CSFV in Vietnam.

Does Financial Integration Matter for Financial Development? Evidence from the East Asian and Pacific Region

Farhad Taghizadeh-Hesary,Nguyet Thi Minh Phi,Hanh Hoang Thi Hong,Vu Tuan Chu 세종대학교 경제통합연구소 2019 Journal of Economic Integration Vol.34 No.4

This paper assesses the impact of financial integration on financial development and establishes thresholds for materializing gains of financial advances from financial globalization using a sample of 34 countries from the East Asian and Pacific region. Following the approaches of Kose et al. (2011) and Asongu and De Moor (2016), we test non-linearity within the financial openness and financial development nexus through semi-parametric ordinary least-squares regression, and then, we develop threshold dynamics models. According to our findings, the effect of financial integration on financial development significantly changes across different financial inflows. When using external debt as a proxy for financial openness, there exists a robust significant inverted U-shaped relationship between financial integration and financial development. The empirical findings also suggest that the financial integration-development nexus is contingent on the level of trade openness, national income, and institutional quality. The results are robust to different measures of financial development and integration, the inclusion of other determinants of financial development, and considerations of endogeneity.