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 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 Improved Refractive Index Sensitivity Utilizing Long-Period Gratings with Periodic Corrugations on Cladding

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Anthony Lim ◽  
Wen Bin Ji ◽  
Swee Chuan Tjin
Keyword(s):  
Refractive Index ◽  
Cost Effective ◽  
Experimental Results ◽  
Refractive Index Sensitivity ◽  
Long Period ◽  
Specimen Collection ◽  
Long Period Gratings ◽  
Highly Sensitive ◽  
Index Sensitivity

A new structure of Long-Period Gratings (LPGs) sensor is introduced as a sensitive ambient RI sensor. This structure consists of creating periodic corrugations on the cladding of the LPG. The experimental results show that this LPG structure has good performances in terms of linearity and sensitivity and serves as a highly sensitive and cost-effective sensor. It also has the advantage of portability as the corrugation can also serve as the reservoir for the specimen collection to be tested.

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.

scholarly journals Refractive index sensing with Fano resonances in silicon oligomers

2017 ◽  
Vol 375 (2090) ◽  
pp. 20160070 ◽  
Author(s):  
Katie E. Chong ◽  
Henry W. Orton ◽  
Isabelle Staude ◽  
Manuel Decker ◽  
Andrey E. Miroshnichenko ◽  
...  
Keyword(s):  
Refractive Index ◽  
Figure Of Merit ◽  
Spectral Features ◽  
Fano Resonances ◽  
Refractive Index Sensitivity ◽  
New Horizons ◽  
Refractive Index Sensing ◽  
Index Sensitivity

We demonstrate experimentally refractive index sensing with localized Fano resonances in silicon oligomers, consisting of six disks surrounding a central one of slightly different diameter. Owing to the low absorption and narrow Fano-resonant spectral features appearing as a result of the interference of the modes of the outer and the central disks, we demonstrate refractive index sensitivity of more than 150 nm RIU −1 with a figure of merit of 3.8. This article is part of the themed issue ‘New horizons for nanophotonics’.

scholarly journals Tunable Fano Resonances in an Ultra-Small Gap

2020 ◽  
Vol 10 (7) ◽  
pp. 2603
Author(s):  
Fuqiang Yao ◽  
Fang Li ◽  
Zhicong He ◽  
Yahui Liu ◽  
Litu Xu ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Performance ◽  
Figure Of Merit ◽  
Silver Film ◽  
Destructive Interference ◽  
Refractive Index Sensitivity ◽  
Thin Aluminum ◽  
Index Sensitivity ◽  
Index Unit ◽  
Dielectric Environment

A Fano resonance is experimentally observed in a single silver nanocube separated from a supporting silver film by a thin aluminum oxide film. The resonance spectrum is modulated by changing the size of the silver nanocube and its distance from the silver film. The system is fabricated by a bottom-up process with an accurately controlled nanogap at the sub-6-nm scale. The simulation result shows that the destructive interference between the dipole mode and the quadrupole mode in this “nanocube on mirror” (NCoM) structure is responsible for the resonance. The spectra red-shifted as the size of the silver nanocube increased and its distance from the silver film decreased. In addition, a refractive index sensitivity of the spectrum of 140 meV/RIU (refractive index unit), with a 2.4 figure of merit, is obtained by changing the dielectric environment around the silver nanocube. This work will enable the development of high-performance tunable optical nanodevices based on NCoM structures.

scholarly journals Analysis of Scaling Law and Figure of Merit of Fiber-Based Biosensor

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jui-Teng Lin ◽  
Da-Chuan Cheng ◽  
Minshan Jiang ◽  
Yueh-Sheng Chiang ◽  
Hsia-Wei Liu
Keyword(s):  
Refractive Index ◽  
Aspect Ratio ◽  
Figure Of Merit ◽  
Scaling Laws ◽  
Scaling Law ◽  
Optimal Designs ◽  
Plasmon Excitation ◽  
Refractive Index Sensitivity ◽  
Optimal Value ◽  
Index Sensitivity

This paper presents a normalized transmitted signal (NTS) of a fiber-based sensor using gold nanorods as the plasmon excitation medium of the evanescent wave. The NTS and the refractive index (RI) sensitivity is calculated as a function of the gold aspect ratio (R), the RI of the sensing medium, and a scaling parameter given by the ratio of the fiber length and its diameter. Finally, the optimal value of gold aspect ratio is calculated to beR= (3.0–4.0) for maximum figure of merits (FOMs) defined by the ratio of the refractive index sensitivity and the full width at half maximum. The scaling laws and the FOM presented in this paper may serve as the guidelines for optimal designs in fiber-based nanosensors.

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.

Ferromagnetic Resonance Biosensor for Homogeneous and Volumetric Detection of DNA

2017 ◽  
Author(s):  
Bo Tian ◽  
Peter Svedlindh ◽  
Mattias Strömberg ◽  
Erik Wetterskog
Keyword(s):  
Magnetic Nanoparticles ◽  
Ferromagnetic Resonance ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Rolling Circle Amplification ◽  
Resonance Field ◽  
Isothermal Amplification ◽  
Detection Sensitivity ◽  
Serum Samples ◽  
Rolling Circle

In this work, we demonstrate for the first time, a ferromagnetic resonance (FMR) based homogeneous and volumetric biosensor for magnetic label detection. Two different isothermal amplification methods, <i>i.e.</i>, rolling circle amplification (RCA) and loop-mediated isothermal amplification (LAMP) are adopted and combined with a standard electron paramagnetic resonance (EPR) spectrometer for FMR biosensing. For RCA-based FMR biosensor, binding of RCA products of a synthetic Vibrio cholerae target DNA sequence gives rise to the formation of aggregates of magnetic nanoparticles. Immobilization of nanoparticles within the aggregates leads to a decrease of the net anisotropy of the system and a concomitant increase of the resonance field. A limit of detection of 1 pM is obtained with an average coefficient of variation of 0.16%, which is superior to the performance of other reported RCA-based magnetic biosensors. For LAMP-based sensing, a synthetic Zika virus target oligonucleotide is amplified and detected in 20% serum samples. Immobilization of magnetic nanoparticles is induced by their co-precipitation with Mg<sub>2</sub>P<sub>2</sub>O<sub>7</sub> (a by-product of LAMP) and provides a detection sensitivity of 100 aM. The fast measurement, high sensitivity and miniaturization potential of the proposed FMR biosensing technology makes it a promising candidate for designing future point-of-care devices.<br>

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