Papers by Keyword: Biosensor

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Authors: H. Liu, N. Zhang, Zi Chao Shiah, X. Zhou
Abstract: This paper reports the fabrication, testing and characterization of an optofluidic sensor for biological sample detection at nanoscale. This biosensor consists of a two-layer structure fabricated by micro- and nanofabrication technology. A microchannel and its fluid connections have been patterned and formed in the silicon and glass. Gold nanoparticles have been fabricated by nanosphere lithography (NSL) on glass. The device has been tested and characterized by localized surface plasmon resonance (LSPR) experiment using a UV/vis spectrometer to obtain the absorbance as a function of wavelength. This device has innovatively integrated microfluidic and plasmonic technology in chip-level and the testing results show that the sensitivity is very high and suitable for biosensing. This device exhibits great potentials to yield ultra-sensitive bio-detection and precise control of ultra-small amount of bio-fluids.
Authors: Sira Srinives, Worasak Klongthong, Kanin Selamassakul, Navapass Peaunbida, Suchaporn Jiamjitton, Chinnawich Phamornnak, Chotiros Plabplueng, Bovornlak Oonkhanond, Tawatchai Charinpanitkul
Abstract: Graphene is a single-to-few layer carbon sheet, consisting of carbon atoms hybridizing with one another via sp2 configuration, providing outstanding mechanical, electrical, and electrochemical properties that can be utilized in various applications. In this work, we synthesized graphene powder via a modified Hummers method to obtain electrically insulating graphene oxide (GO), and converted the GO to semiconducting reduced graphene oxide (rGO) using L-ascorbic acid as a reducing agent. The rGO was re-dispersed in DI water and cast on prefabricated electrodes to create an rGO film chemiresistive sensor.The rGO sensor was shown to detect changes in buffer pH and cell concentrations of three different cells: human breast cancer cells (MDA-MB-231); non-small-cell lung cancer cells (A549); and fibroblast cells (L929). Sensor performances were determined in terms of "sensitivity", ratio of normalized resistance change upon exposure to a certain analyte concentration, and the analyte concentration. Our studies serve as strong evidence that the rGO-based chemiresistive sensor can be used for a quick and easy test in indicating buffer pH, or quantifying concentrations of a known cell.
Authors: Wu Ming Zhang, Zhen Yu Li, Tao Chen, Jian Jiang Yao, Yang Lv, Min Li, Guang Li
Abstract: A hybrid-structured microfluidic chip integrating optical fiber sensing technology and bioluminescence chemical reaction mechanism was developed for rapid and sensitive detection of adenosine 5’-triphosphate (ATP). This microfluidic chip was fabricated with five distinct layers for the successive steps of sample-enzyme reagent mixing, bioluminescence chemical reaction and scatting light collection. The experimental results demonstrated that the provided hybrid-structure improved the sensitivity, response time, reagent consumption and other properties of chip. This improvement enables the microfluidic chip to attain a sensitive ATP detection in the range from 10-9 to 10-4 M with excellent linearity (R2 = 0.9967), low detection error (CV < 15%), and tiny reagent consumption (< 20 μL). These achievements thus indicated that the chip developed in this study possess the advantages such as high sensitivity, quick-response and small reagent consumption.
Authors: Ya Min Shi, Guo Guang Rong, Dan Ni Wang, Shu Lin Zhang, Yong Xin Zhu
Abstract: Though techniques in medicine develop in a very fast pace, tuberculosis still bothers researchers for its extensive existence. It is urgent to find faster, cheaper and more convenient new ways for diagnosis of tuberculosis. In this paper, we demonstrated a novel serodiagnostic method based on porous silicon thin film. Porous silicon has been proven feasible to function as biosensors in a lot of research. While most serodiagnostic methods are labeled detection, our porous silicon biosensor is a label-free technique. This kind of biosensor is manufactured in a simple way with relatively lower cost while providing an excellent sensitivity and specificity. Through the experiment of LAM antigen and anti-LAM antibody interacting on a porous silicon thin film platform, we proved the feasibility of our new detection approach. Furthermore, we also provided some innovation insights for improving our biosensor which may help it be practically applicable.
Authors: Liang Gao, Guo Hui Yuan, Xing Li Liu, Yu Ren Chen
Abstract: We design a double slots based on micro-ring resonator on silicon-on-insulator (SOI). An asymmetric structure is considered for the ring waveguide in order to improve the sensor's bending efficiency. Finite-difference time-domain (FDTD) method is used to analyze and optimize this sensor. The optimized size of the sensor is below 25×15μm2. Numerical analysis shows that when the radius of the micro-ring is about 5μm, the sensitivity reaches a value of 708nm/RIU, which is ten times of that of the conventional micro-ring sensor. Quality factor (Q factor) of 580 and free spectral range (FSR) of 33nm are also obtained. Our analysis also shows that the sensor has good sensing characteristics to different organic solutions.
Authors: Ming Yuan Guan, Guo Yin Huang, Gui Yin Li, Guo Wei Shi, Long Fei Ma, Shi Nin Yin, Yong Huang, Jin Tao Liang
Abstract: Immunoglobulin G (IgG) is one of the most important factors in diagnosing some diseases in clinic. A novel biosensor for dectection of IgG based on light-addressable potentiometric sensor (LAPS) was presented in this paper. The LAPS measurement system included the LAPS sensor, light source, the electrode and the electrochemical workstation. The LAPS sensor was fabricated by the method of the Layer-by-Layer Self-Assembly (LBL-SA). The IgG antibody modified onto the silicon wafer of LAPS to capture the corresponding antigen by the specific immune response which has an effect on the sensitive of LAPS to change the photocurrent. The laser diode (LD) light source of 890 nm wavelength was chose as illuminant to drive the LAPS to create the photocurrent. A FPGA was introduced to control the LD and generate a sine wave signal with the special frequency. Different concentration of IgG arranged 50-150μg/mL was detected by the LAPS system. A calibration curve that represented linear correlation between the bias voltage values and theconcentration of IgG was illustrated, and the linear correlation coefficient was 0.9943. This new biosensor can be very useful for detection of IgG based on the LAPS principle.
Authors: Sh. Ebrahim, R. El-Raey, A. Hefnawy, H. Ibrahim, M. Soliman
Abstract: Polyaniline nanofibers were prepared chemically in both emiraldine base (EB) and emiraldine salt (ES) forms. The composite of polyaniline emiraldine salt with single walled carbon nanotubes (SWCNTs) was developed. Electrochemical sensors based on polyaniline nanofibers and its composite have been developed for the detection of chloropyrifos. Chloropyrifos exhibits one well defined reduction peak. The maximum peak current was linearly related to chloropyrifos concentration in the range from 0.2 μM to 1.4 μM. It was found that the SWCNTs improved the sensitivity of the polyaniline base graphite electrode from 3.0 mA/μM for polyaniline base to 9.69 mA/μM for ES-SWCNTs composite electrode.
Authors: Ting Deng, Zhong Cao, Guo Li Shen
Abstract: An electrochemical impedance biosensor was proposed for the detection of small molecule biotin based on the plasma-polymerized films (PPF) and the bioaffinity difference between an analyte (biotin) and an analogue compound (HABA) in binding avidin. Avidin formed a metastable complex with 2-[(4-hydroxyphenyl)azo]benzoic acid (HABA) immobilized on the electrode surface. When the sensor contacts a sample solution containing biotin, the avidin was released from the sensor surface to form a more stable complex with biotin in solution. The impedance spectra change recorded is proportional to the desorbed mass of avidin, and there is a clear mathematic relationship between the impedance change and the biotin concentration. The proposed electrochemical impedance bioaffinity sensor has nice response to biotin in the range of 4.8×10-9–5.6×10-4 M. The sensor could be regenerated under very mild conditions simply by reimmersion of the sensor into a biotin solution to desorb the surplus avidin.
Authors: Vijayalakshmi Velusamy, Khalil Arshak, Olga Korostynska, Ahmed Al-Shamma'a
Abstract: Detailed in this paper is the design of a novel handheld electrochemical analyzer system interfaced to a smart phone, which provides versatile and cost-effective solution for real-time sensing applications. It was characterised for electron transfer events associated with chemical and biological samples. The presented design is implemented based on the Arduino nanoopen source electronics prototyping platform. The versatility of the instrument is further demonstrated by employing the electrochemical analyser to a modified electrochemical cell which formed the basis of a DNA biosensor. Cyclic voltammetry technique was used to impose a triangular waveform on an electrochemical cell and the resulting current through the cell was then monitored. The DNA biosensor generated unique electrical signals in real-time between complementary and non-complementary oligonucleotides sequences of the Bacillus cereus DNA. The effects of hybridization and non-specific binding were compared when the probe DNA molecules were immobilized on a conducting polymer matrix. The results showed that the probe DNA immobilized using electrochemical adsorption yielded better hybridization signals compared to other immobilization methods. The performance of the DNA sensor proved to be effective in terms of selectivity, sensitivity and reproducibility of hybridization events. Analysis of these DNA probes showed that the minimum level of detection was 33.3 pg/ml.
Authors: Guo Yin Huang, Long Fei Ma, Ming Yuan Guan, Jin Tao Liang, Yong Huang, Gui Yin Li
Abstract: In this paper, a novel hIg E aptamer biosensor was designed base on the core-shell Fe3O4@Au magnetic composite nanoparticles (Fe3O4@Au NPs). Firstly, Fe3O4@Au NPs were prepared by one-step reduction process with Fe3O4 nanoparticles (Fe3O4 NPs) as magnetic core and hydroxylamine hydrochloride as deoxidizer. Then, the morphology, composition, and properties of Fe3O4@Au NPs were characterized by scanning electron microscope (SEM), fourier translation infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and so on. Lastly, Human immunoglobulin E (hIg E) was used as the model analyte, a hIg E aptamer biosensor was presented which the hIg E antibody is covalently immobilized as the capture probe on Fe3O4@Au NPs surface, and hIg E aptamer was used as the detection probe. After the hIg E antigen was captured, the ascorbic acid 2-phosphate (AAP) formed ascorbic acid (AA) in the presence of alkaline phosphatase (ALP). The AA reduced the silver ions (Ag+) in the solution to silver metal that preferentially deposited on surface of the Fe3O4@Au NPs. The amount of deposited silver could be quantified using the electrochemical methods. The oxidation current of Ag0 was linear with the concertration of hIg E over the range 0.25~2.0 μg/mL. Therefore, the hIg E aptamer biosensor possessed higher sensitivity, low detection limit and rapid response speed.
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