scholarly journals All-Metal Terahertz Metamaterial Biosensor for Protein Detection

2021 ◽  
Author(s):  
Gangqi Wang ◽  
Fengjie Zhu ◽  
Tingting Lang ◽  
Jianjun Liu ◽  
Zhi Hong ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Refractive Index ◽  
Bovine Serum Albumin ◽  
Figure Of Merit ◽  
Limit Of Detection ◽  
Protein Detection ◽  
Cost Effective ◽  
Detection Sensitivity ◽  
Drilling Technology ◽  
Simulation Results

Abstract In this paper, a terahertz (THz) biosensor based on all-metal metamaterial is theoretically investigated and experimentally verified. This THz metamaterial biosensor uses stainless steel materials that are manufactured via laser-drilling technology. The simulation results show that the maximum refractive index (RI) sensitivity and the figure of merit (FOM) of this metamaterial sensor are 294.95 GHz/RIU and 4.03, respectively. Then, bovine serum albumin (BSA) was chosen as the detection substance to assess this biosensor’s effectiveness. The experiment results show that the detection sensitivity is 72.81 GHz/(ng/mm2) and the limit of detection (LOD) is 0.035 mg/mL. This THz metamaterial biosensor is simple, cost-effective, easy to fabricate, and have great potential in various biosensing applications.

scholarly journals All-metal terahertz metamaterial biosensor for protein detection

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Gangqi Wang ◽  
Fengjie Zhu ◽  
Tingting Lang ◽  
Jianjun Liu ◽  
Zhi Hong ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Figure Of Merit ◽  
Limit Of Detection ◽  
Protein Detection ◽  
Cost Effective ◽  
Detection Sensitivity ◽  
Refractive Index Sensitivity ◽  
Drilling Technology ◽  
Simulation Results ◽  
Index Sensitivity

AbstractIn this paper, a terahertz (THz) biosensor based on all-metal metamaterial is theoretically investigated and experimentally verified. This THz metamaterial biosensor uses stainless steel materials that are manufactured via laser-drilling technology. The simulation results show that the maximum refractive index sensitivity and the figure of merit of this metamaterial sensor are 294.95 GHz/RIU and 4.03, respectively. Then, bovine serum albumin was chosen as the detection substance to assess this biosensor’s effectiveness. The experiment results show that the detection sensitivity is 72.81 GHz/(ng/mm2) and the limit of detection is 0.035 mg/mL. This THz metamaterial biosensor is simple, cost-effective, easy to fabricate, and has great potential in various biosensing applications.

scholarly journals A Critical Factor for Quantifying Proteins in Unmodified Gold Nanoparticles-Based Aptasensing: The Effect of pH

Chemosensors ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 98
Author(s):  
Dai Lu ◽  
Dong Zhang ◽  
Qian Zhao ◽  
Xiangyang Lu ◽  
Xingbo Shi
Keyword(s):  
Gold Nanoparticles ◽  
Limit Of Detection ◽  
Protein Detection ◽  
Critical Factor ◽  
Cost Effective ◽  
Protein Corona ◽  
Target Protein ◽  
Universal Method ◽  
Salt Addition ◽  
Positively Charged

Unmodified gold nanoparticles (AuNPs)-based aptasensing (uGA) assay has been widely implemented in the determination of many different targets, but there are few reports on protein detection using uGA. Here, we designed a uGA assay for protein detection including the elimination of interfering proteins. Positively charged protein can be absorbed directly on the surface of AuNPs to form “protein corona”, which results in the aggregation of AuNPs even without salt addition, thereby preventing target protein detection. To overcome this problem, we systematically investigated the effect of modifying the pH of the solution during the uGA assay. A probe solution with a pH slightly higher than the isoelectric points (pI) of the target protein was optimal for protein detection in the uGA assay, allowing the aptamer to selectively detect the target protein. Three proteins (beta-lactoglobulin, lactoferrin, and lysozyme) with different pI were chosen as model proteins to validate our method. Positively charged interfering proteins (with pIs higher than the optimal pH) were removed by centrifugation of protein corona/AuNPs aggregates before the implementation of actual sample detection. Most importantly, the limit of detection (LOD) for all three model proteins was comparable to that of other methods, indicating the significance of modulating the pH. Moreover, choosing a suitable pH for a particular target protein was validated as a universal method, which is significant for developing a novel, simple, cost-effective uGA assay for protein detection.

scholarly journals Proposal of De Novo Antigen Test for COVID-19: Ultrasensitive Detection of Spike Proteins of SARS-CoV-2

Diagnostics ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 594 ◽  
Author(s):  
Yuta Kyosei ◽  
Mayuri Namba ◽  
Sou Yamura ◽  
Rikiya Takeuchi ◽  
Noriko Aoki ◽  
...  
Keyword(s):  
De Novo ◽  
Limit Of Detection ◽  
False Negative ◽  
Cost Effective ◽  
Detection Sensitivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antigen Test ◽  
Virus Rna ◽  
Antigen Tests ◽  
Spike Proteins

Polymerase chain reaction (PCR)-based antigen tests are technically difficult, time-consuming, and expensive, and may produce false negative results requiring follow-up confirmation with computed tomography. The global coronavirus disease 2019 (COVID-19) pandemic has increased the demand for accurate, easy-to-use, rapid, and cost-effective antigen tests for clinical application. We propose a de novo antigen test for diagnosing COVID-19 using the combination of sandwich enzyme-linked immunosorbent assay and thio-nicotinamide adenine dinucleotide (thio-NAD) cycling. Our test takes advantage of the spike proteins specific to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The limit of detection of our test was 2.3 × 10−18 moles/assay. If the virus has ~25 spike proteins on its surface, our method should detect on the order of 10−20 moles of virus/assay, corresponding to ~104 copies of the virus RNA/assay. The detection sensitivity approaches that of PCR-based assays because the average virus RNA load used for PCR-based assays is ~105 copies per oro- or naso-pharyngeal swab specimen. To our knowledge, this is the first ultrasensitive antigen test for SARS-CoV-2 spike proteins that can be performed with an easy-to-use microplate reader. Sufficient sensitivity can be achieved within 10 min of thio-NAD cycling. Our antigen test allows for rapid, cost-effective, specific, ultrasensitive, and simultaneous multiple measurements of SARS-CoV-2, and has broad application for the diagnosis for COVID-19.

Exploring Refractive Index Ultra Compact Nano Sensor Using Photonic Crystal Resonant Cavities

2020 ◽  
Vol 17 (7) ◽  
pp. 2926-2931
Author(s):  
Masoud Mohammadi ◽  
Mahmood Seifouri ◽  
Elham Boyerahmadi ◽  
R. Udaiyakumar
Keyword(s):  
Refractive Index ◽  
Photonic Crystal ◽  
Integrated Circuits ◽  
Quality Factor ◽  
Optical Sensors ◽  
Figure Of Merit ◽  
Limit Of Detection ◽  
Transmission Efficiency ◽  
Resonant Cavities ◽  
The Mean

In this paper, an ultra-compact photonic crystal sensor based resonant cavities is proposed with improved quality factor, sensitivity and detection limit. The proposed sensor has 2D pillar photonic crystals with hexagonal array of dielectric rods. The refractive index of dielectric rods, radius of rods, filling factor (r/a) and lattice constant of the proposed structure are 3.46, 108 nm, 0.2 and 542 nm, respectively. The mean transmission efficiency, Quality factor, sensitivity, Figure of Merit (FOM) and limit of detection (LOD) are calculated as 92.2%, 9975.8, 371 nm/RIU, 2366 and 4.5 x 10-5 RIU, respectively. The corresponding electric field distributions and it band characteristics are studied using finite different time domain method (FDTD) and plan wave expansion (PWE). The cross-section of the proposed structure is 86 /xm2 and is desirable for photonic integrated circuits (PIC) and ultra-compact optical sensors.

scholarly journals Dual Fano Resonances Induced by Rectangle-based Plasmonic Resonator for Refractive Index Nano-sensor

2021 ◽  
Vol 2125 (1) ◽  
pp. 012005
Author(s):  
Yang Zhang
Keyword(s):  
Refractive Index ◽  
Figure Of Merit ◽  
Important Application ◽  
Refractive Index Sensor ◽  
Fano Resonances ◽  
Metal Insulator ◽  
Metal Insulator Metal ◽  
Simulation Results ◽  
Photonic Circuit ◽  
Plasmonic Resonator

Abstract A tunable dual Fano-like plasmonic structure consisting of metal-insulator-metal (MIM), baffle and a rectangular cavity containing two identical rectangular metal blocks is obtained. Numerical simulation results show that there are dual Fano resonances in the transmission spectrum of the structure, which can be tuned by changing the geometric parameters of the structure. In addition, due to the apparent asymmetry of the Fano resonances, the system was developed as an effective refractive index sensor (RIS) with a sensitivity of 853 nm/RIU and figure of merit (FOM) of 1631. It is considered that this structure has important application value in high integrated photonic circuit.

scholarly journals Bovine Serum Albumin Protein Detection by a Removable SPR Chip Combined with a Specific MIP Receptor

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 218
Author(s):  
Francesco Arcadio ◽  
Luigi Zeni ◽  
Chiara Perri ◽  
Girolamo D’Agostino ◽  
Giudo Chiaretti ◽  
...  
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Limit Of Detection ◽  
Low Cost ◽  
Protein Detection ◽  
Slab Waveguide ◽  
Label Free ◽  
Sensor Configuration ◽  
Application Fields

Nowadays, the development of simple, fast, and low-cost selective sensors to detect substances of interest is of great importance in several application fields. Among this kind of sensors, those based on surface plasmon resonance (SPR) represent a promising category, since they are highly sensitive, versatile, and label-free. In this work, an SPR probe, based on a poly(methyl methacrylate) (PMMA) slab waveguide covered by a gold nanofilm, combined with a specific molecularly imprinted polymer (MIP) receptor for bovine serum albumin (BSA) protein, has been realized and experimentally characterized. The obtained experimental results have shown a limit of detection (LOD) equal to about 8.5 × 10−9 M. This value is smaller than the one achieved by another SPR probe, based on a D-shaped plastic optical fiber (POF), functionalized with the same MIP receptor; more specifically, the obtained LOD was reduced by about three orders of magnitude with respect to the POF configuration. Moreover, concerning the D-shaped POF configuration, no manufacturing process is present in the proposed sensor configuration. In addition, fibers are used only to connect the simple sensor chip with a light source and a detector, promoting a bio-chemical sensing approach based on disposable, low-cost, and removable chips.

scholarly journals Demonstration of a Low-Cost and Portable Optical Cavity-Based Sensor through Refractive Index Measurements

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2193 ◽  
Author(s):  
Donggee Rho ◽  
Caitlyn Breaux ◽  
Seunghyun Kim
Keyword(s):  
Refractive Index ◽  
Detection Method ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Differential Detection ◽  
Low Pass ◽  
Portable System ◽  
Simulation Results

An optical cavity-based sensor using a differential detection method has been proposed for point-of-care diagnostics. We developed a low-cost and portable optical cavity-based sensor system using a 3D printer and off-the-shelf optical components. In this paper, we demonstrate the sensing capability of the portable system through refractive index measurements. Fabricated optical cavity samples were tested using the portable system and compared to simulation results. A referencing technique and digital low pass filtering were applied to reduce the noise of the portable system. The measurement results match the simulation results well and show the improved linearity and sensitivity by employing the differential detection method. The limit of detection achieved was 1.73 × 10−5 Refractive Index Unit (RIU), which is comparable to other methods for refractive index sensing.

scholarly journals A Single-Substrate Biosensor with Spin-Coated Liquid Crystal Film for Simple, Sensitive and Label-Free Protein Detection

Biosensors ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 374
Author(s):  
Po-Chang Wu ◽  
Chao-Ping Pai ◽  
Mon-Juan Lee ◽  
Wei Lee
Keyword(s):  
Liquid Crystal ◽  
Film Thickness ◽  
Limit Of Detection ◽  
Protein Detection ◽  
Cost Effective ◽  
Antibody Concentration ◽  
Label Free ◽  
Free Protein ◽  
Single Substrate ◽  
Simplified Procedure

A liquid crystal (LC)-based single-substrate biosensor was developed by spin-coating an LC thin film on a dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP)-decorated glass slide. Compared with the conventional sandwiched cell configuration, the simplified procedure for the preparation of an LC film allows the film thickness to be precisely controlled by adjusting the spin rate, thus eliminating personal errors involved in LC cell assembly. The limit of detection (LOD) for bovine serum albumin (BSA) was lowered from 10−5 g/mL with a 4.2-μm-thick sandwiched cell of the commercial LC E7 to 10−7 g/mL with a 4.2-μm-thick spin-coated E7 film and further to 10−8 g/mL by reducing the E7 film thickness to 3.4 μm. Moreover, by exploiting the LC film of the highly birefringent nematic LC HDN in the immunodetection of the cancer biomarker CA125, an LOD comparable to that determined with a sandwiched HDN cell was achieved at 10−8 g/mL CA125 using a capture antibody concentration an order of magnitude lower than that in the LC cell. Our results suggest that employing spin-coated LC film instead of conventional sandwiched LC cell provides a more reliable, reproducible, and cost-effective single-substrate platform, allowing simple fabrication of an LC-based biosensor for sensitive and label-free protein detection and immunoassay.

scholarly journals Comparison of Quantitative Detection Methods Based on Molecular Fluorescence Spectroscopy and Chromatographic Techniques Used for the Determination of Bisphenol Compounds

2021 ◽  
Vol 22 (19) ◽  
pp. 10569
Author(s):  
Joanna Orzel ◽  
Pawel Swit
Keyword(s):  
Limit Of Detection ◽  
Cost Effective ◽  
Detection Sensitivity ◽  
Detection Methods ◽  
Quantitative Detection ◽  
Range Limit ◽  
Thermal Paper ◽  
Validation Parameters ◽  
Molecular Fluorescence

Analytical methods using the fluorescence properties of bisphenols (BPA, BPF and BPS) and their complexes with β-cyclodextrin and methyl-β-cyclodextrin were developed. The methods were applied for the analysis of thermal paper and canned food. Their performance was compared with a standard HPLC approach with a diode array and fluorescence detections. For comparison purposes, basic validation parameters (linear range, limit of detection, sensitivity, precision) were evaluated. It was concluded the developed methods facilitate fast and cost-effective determination of three bisphenol species in liquid samples, similar to the HPLC performance. They are also environmentally friendly. BPA, BPF and BPS can be routinely determined with the presented approach.

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