Porous Silicon Immunosensor for Label-Free Detection of SpaA

2010 ◽  
Vol 44-47 ◽  
pp. 2472-2476
Author(s):  
Tao Jiang ◽  
Xiao Yi Lv ◽  
Fu Ru Zhong ◽  
Jia Qing Mo ◽  
Yi Xian Tu ◽  
...  
Keyword(s):  
Detection Limit ◽  
Porous Silicon ◽  
Reflection Spectrum ◽  
High Specificity ◽  
Red Shift ◽  
Label Free ◽  
Controlled Experiments ◽  
Label Free Detection ◽  
Antigen Antibody ◽  
Immune Antibody

A novel immunosensor based on porous silicon (PSi) for antigen detection was reported in this paper. The antigen (SpaA) and the specificity of the antibodies are employed as the target and the probe in our laboratory, respectively. The immunosensor structure was prepared using bioconjungation. After the antigen-antibody reaction, the red shift of the reflection spectrum of the immunosensor increases in proportion to the concentration of SpaA. The sensitivity of this immunosensor is 41nm/ µg•ml-1 and the detection limit is 2.44×102pg•ml-1, they are better compared with our previous work by using this method. Controlled experiments were also presented with non-immune antibody and the results show that this immunosensor possesses high specificity.

scholarly journals Affinity Sensors for the Diagnosis of COVID-19

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 390
Author(s):  
Maryia Drobysh ◽  
Almira Ramanaviciene ◽  
Roman Viter ◽  
Arunas Ramanavicius
Keyword(s):  
Field Effect Transistors ◽  
Resonance Field ◽  
Analytical Signal ◽  
Nucleic Acid Hybridization ◽  
Detection Methods ◽  
Label Free ◽  
Infected People ◽  
Label Free Detection ◽  
Main Instrument ◽  
Antigen Antibody

The coronavirus disease 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was proclaimed a global pandemic in March 2020. Reducing the dissemination rate, in particular by tracking the infected people and their contacts, is the main instrument against infection spreading. Therefore, the creation and implementation of fast, reliable and responsive methods suitable for the diagnosis of COVID-19 are required. These needs can be fulfilled using affinity sensors, which differ in applied detection methods and markers that are generating analytical signals. Recently, nucleic acid hybridization, antigen-antibody interaction, and change of reactive oxygen species (ROS) level are mostly used for the generation of analytical signals, which can be accurately measured by electrochemical, optical, surface plasmon resonance, field-effect transistors, and some other methods and transducers. Electrochemical biosensors are the most consistent with the general trend towards, acceleration, and simplification of the bioanalytical process. These biosensors mostly are based on the determination of antigen-antibody interaction and are robust, sensitive, accurate, and sometimes enable label-free detection of an analyte. Along with the specification of biosensors, we also provide a brief overview of generally used testing techniques, and the description of the structure, life cycle and immune host response to SARS-CoV-2, and some deeper details of analytical signal detection principles.

scholarly journals Impedimetric Immunosensor Utilizing Polyaniline/Gold Nanocomposite-Modified Screen-Printed Electrodes for Early Detection of Chronic Kidney Disease

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3990 ◽  
Author(s):  
Muhammad Omar Shaikh ◽  
Boyanagunta Srikanth ◽  
Pei-Yu Zhu ◽  
Cheng-Hsin Chuang
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Early Detection ◽  
Electrochemical Impedance ◽  
High Specificity ◽  
Homogeneous Distribution ◽  
Label Free ◽  
Gold Nanocrystals ◽  
Working Electrode ◽  
Label Free Detection

The presence of small amounts of human serum albumin (HSA) in urine or microalbuminuria (30–300 µg/mL) is a valuable clinical biomarker for the early detection of chronic kidney disease (CKD). Herein, we report on the development of an inexpensive and disposable immunosensor for the sensitive, specific, and label-free detection of HSA using electrochemical impedance spectroscopy (EIS). We have utilized a simple one-step screen-printing protocol to fabricate the carbon-based three-electrode system on flexible plastic substrates. To enable efficient antibody immobilization and improved sensitivity, the carbon working electrode was sequentially modified with electropolymerized polyaniline (PANI) and electrodeposited gold nanocrystals (AuNCs). The PANI matrix serves as an interconnected nanostructured scaffold for homogeneous distribution of AuNCs and the resulting PANI/AuNCs nanocomposite synergically improved the immunosensor response. The PANI/AuNCs-modified working electrode surface was characterized using scanning electron microscopy (SEM) and the electrochemical response at each step was analyzed using EIS in a ferri/ferrocyanide redox probe solution. The normalized impedance variation during immunosensing increased linearly with HSA concentration in the range of 3–300 µg/mL and a highly repeatable response was observed for each concentration. Furthermore, the immunosensor displayed high specificity when tested using spiked sample solutions containing different concentrations of actin protein and J82 cell lysate (a complex fluid containing a multitude of interfering proteins). Consequently, these experimental results confirm the feasibility of the proposed immunosensor for early diagnosis and prognosis of CKD at the point of care.

scholarly journals A liquid-crystal-based DNA biosensor for pathogen detection

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Mashooq Khan ◽  
Abdur Rahim Khan ◽  
Jae-Ho Shin ◽  
Soo-Young Park
Keyword(s):  
Liquid Crystal ◽  
Pathogen Detection ◽  
Grid Cell ◽  
High Specificity ◽  
Erwinia Carotovora ◽  
Optical Microscope ◽  
Label Free ◽  
Label Free Detection ◽  
Homeotropic Orientation ◽  
Tem Grid

Abstract A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection.

A nanofluidic device for ultrasensitive and label-free detection of tetracycline in association with γ-cyclodextrin and GO

2021 ◽  
Vol 13 (15) ◽  
pp. 1832-1838
Author(s):  
Jiaxi Cheng ◽  
Fenghua Jiang ◽  
Siqi Zhang
Keyword(s):  
Detection Limit ◽  
Water Samples ◽  
Recovery Rate ◽  
Label Free ◽  
Detection Range ◽  
Low Detection Limit ◽  
Sensing Platform ◽  
Label Free Detection ◽  
Nanofluidic Device

We develop a label-free, sensitive and selective nanochannel sensing platform for detection of TC. The nanosensor provided a low detection limit, a wide detection range and excellent recovery rate in different water samples.

Rapid and label-free detection of protein a by aptamer-tethered porous silicon nanostructures

2017 ◽  
Vol 257 ◽  
pp. 171-177 ◽  
Author(s):  
Katharina Urmann ◽  
Peggy Reich ◽  
Johanna-Gabriela Walter ◽  
Dieter Beckmann ◽  
Ester Segal ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Protein A ◽  
Silicon Nanostructures ◽  
Label Free ◽  
Label Free Detection

scholarly journals 1/f-noise-free optical sensing with an integrated heterodyne interferometer

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ming Jin ◽  
Shui-Jing Tang ◽  
Jin-Hui Chen ◽  
Xiao-Chong Yu ◽  
Haowen Shu ◽  
...  
Keyword(s):  
Detection Limit ◽  
Detection System ◽  
Low Frequency ◽  
Frequency Noise ◽  
Label Free ◽  
Surface Charges ◽  
Heterodyne Interferometer ◽  
Nanoparticle Detection ◽  
Cavity Resonances ◽  
Antigen Antibody

AbstractOptical evanescent sensors can non-invasively detect unlabeled nanoscale objects in real time with unprecedented sensitivity, enabling a variety of advances in fundamental physics and biological applications. However, the intrinsic low-frequency noise therein with an approximately 1/f-shaped spectral density imposes an ultimate detection limit for monitoring many paramount processes, such as antigen-antibody reactions, cell motions and DNA hybridizations. Here, we propose and demonstrate a 1/f-noise-free optical sensor through an up-converted detection system. Experimentally, in a CMOS-compatible heterodyne interferometer, the sampling noise amplitude is suppressed by two orders of magnitude. It pushes the label-free single-nanoparticle detection limit down to the attogram level without exploiting cavity resonances, plasmonic effects, or surface charges on the analytes. Single polystyrene nanobeads and HIV-1 virus-like particles are detected as a proof-of-concept demonstration for airborne biosensing. Based on integrated waveguide arrays, our devices hold great potentials for multiplexed and rapid sensing of diverse viruses or molecules.

Electrokinetics-Based Microfluidic Technology for the Rapid Separation and Concentration of Bacteria/Cells/Biomolecules

2014 ◽  
Vol 911 ◽  
pp. 347-351 ◽  
Author(s):  
I Fang Cheng ◽  
Tzu Ying Chen ◽  
Hsien Chang Chang
Keyword(s):  
Cancer Cell ◽  
Electrochemical Impedance ◽  
High Sensitivity ◽  
High Specificity ◽  
Cell Detection ◽  
Label Free ◽  
Rapid Separation ◽  
Whole Cells ◽  
Highly Sensitive ◽  
Label Free Detection

Conventional techniques for detection of bacteria/cell and assessment of cancer cell typically use DNA techniques, Western blot and ELISA kits that are high cost, complicated processes and long time consuming. Our researches focus on rapid, portable, simple and highly sensitive separation and detection of cells/bacteria/biomolecules for field-use diagnosis. An ideal portable biosensor (molecular or whole cells detections) unit must have several important features: rapid detection time (<10 minutes), high sensitivity (pM level for molecular detection, 103 cells/ml for whole cell detection), high specificity, small and inexpensive instrumentation configuration. Electrochemical impedance/conductance sensing is preferred over optical detection because of cost and portability concerns. Cancer cell detection using heterogeneous medical samples require continuous isolation, sorting, and trapping of the target bioparticles and immunocolloids within a diagnostic chip. We have developed several electrokinetic strategies to rapid separation, concentration and detection of cells/bacteria/biomolecules in a microfluidic chip using such as dielectrophoresis (DEP), traveling-wave dielectrophoresis (twDEP) and electrohydrodynamics (EHD). Several key techniques we done, which on a rapid/simple/label-free detection platform for the highly sensitive on-chip separation/identification/quantification will be introduced in this paper.

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