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 Label-Free Electrochemical Biosensor Based on Au@MoS₂–PANI for Escherichia coli Detection

Chemosensors ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 49
Author(s):  
Pushap Raj ◽  
Man Hwan Oh ◽  
Kyudong Han ◽  
Tae Yoon Lee
Keyword(s):  
Escherichia Coli ◽  
Bacterial Infections ◽  
Limit Of Detection ◽  
Bacterial Pathogens ◽  
Cost Effective ◽  
Covalent Immobilization ◽  
Label Free ◽  
Self Assembled Monolayer ◽  
Detection Range ◽  
Linear Detection

Bacterial infections have become a significant challenge in terms of public health, the food industry, and the environment. Therefore, it is necessary to address these challenges by developing a rapid, cost-effective, and easy-to-use biosensor for early diagnosis of bacterial pathogens. Herein, we developed a simple, label-free, and highly sensitive immunosensor based on electrochemical detection using the Au@MoS₂–PANI nanocomposite. The conductivity of the glassy carbon electrode is greatly enhanced using the Au@MoS₂–PANI nanocomposite and a self-assembled monolayer of mercaptopropionic acid on the gold nanoparticle surface was employed for the covalent immobilization of antibodies to minimize the nonspecific adsorption of bacterial pathogens on the electrode surface. The biosensor established a high selectivity and sensitivity with a low limit of detection of 10 CFU/mL, and detected Escherichia coli within 30 min. Moreover, the developed biosensor demonstrated a good linear detection range, practical utility in urine samples, and electrode regenerative studies.

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 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.

An electrochemical impedance biosensor with aptamer-modified pyrolyzed carbon electrode for label-free protein detection

2008 ◽  
Vol 129 (1) ◽  
pp. 372-379 ◽  
Author(s):  
Jung A Lee ◽  
Seongpil Hwang ◽  
Juhyoun Kwak ◽  
Se Il Park ◽  
Seung S. Lee ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Protein Detection ◽  
Carbon Electrode ◽  
Label Free ◽  
Free Protein

scholarly journals The beauty of being (label)-free: sample preparation methods for SWATH-MS and next-generation targeted proteomics

F1000Research ◽  
2014 ◽  
Vol 2 ◽  
pp. 272 ◽  
Author(s):  
Jakob Vowinckel ◽  
Floriana Capuano ◽  
Kate Campbell ◽  
Michael J. Deery ◽  
Kathryn S. Lilley ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Protein Identification ◽  
Protein Detection ◽  
Cost Effective ◽  
High Signal ◽  
Label Free ◽  
Signal Variation ◽  
Signal Stability ◽  
Advantages And Disadvantages ◽  
Free Data

The combination of qualitative analysis with label-free quantification has greatly facilitated the throughput and flexibility of novel proteomic techniques. However, such methods rely heavily on robust and reproducible sample preparation procedures. Here, we benchmark a selection of in gel, on filter, and in solution digestion workflows for their application in label-free proteomics. Each procedure was associated with differing advantages and disadvantages. The in gel methods interrogated were cost effective, but were limited in throughput and digest efficiency. Filter-aided sample preparations facilitated reasonable processing times and yielded a balanced representation of membrane proteins, but led to a high signal variation in quantification experiments. Two in solution digest protocols, however, gave optimal performance for label-free proteomics. A protocol based on the detergent RapiGest led to the highest number of detected proteins at second-best signal stability, while a protocol based on acetonitrile-digestion, RapidACN, scored best in throughput and signal stability but came second in protein identification. In addition, we compared label-free data dependent (DDA) and data independent (SWATH) acquisition on a TripleTOF 5600 instrument. While largely similar in protein detection, SWATH outperformed DDA in quantification, reducing signal variation and markedly increasing the number of precisely quantified peptides.

scholarly journals Carbon Nanotube-Based Electrochemical Biosensor for Label-Free Protein Detection

Biosensors ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 144 ◽  
Author(s):  
Jesslyn Janssen ◽  
Mike Lambeta ◽  
Paul White ◽  
Ahmad Byagowi
Keyword(s):  
Limit Of Detection ◽  
Protein Detection ◽  
Protein Quantification ◽  
Clinical Diagnostics ◽  
Biological Research ◽  
Label Free ◽  
Protein Biomarkers ◽  
Biosensor System ◽  
Elisa Technique ◽  
Standard Protein

There is a growing need for biosensors that are capable of efficiently and rapidly quantifying protein biomarkers, both in the biological research and clinical setting. While accurate methods for protein quantification exist, the current assays involve sophisticated techniques, take long to administer and often require highly trained personnel for execution and analysis. Herein, we explore the development of a label-free biosensor for the detection and quantification of a standard protein. The developed biosensors comprise carbon nanotubes (CNTs), a specific antibody and cellulose filtration paper. The change in electrical resistance of the CNT-based biosensor system was used to sense a standard protein, bovine serum albumin (BSA) as a proof-of-concept. The developed biosensors were found to have a limit of detection of 2.89 ng/mL, which is comparable to the performance of the typical ELISA method for BSA quantification. Additionally, the newly developed method takes no longer than 10 min to perform, greatly reducing the time of analysis compared to the traditional ELISA technique. Overall, we present a versatile, affordable, simplified and rapid biosensor device capable of providing great benefit to both biological research and clinical diagnostics.

An Optical Nanoruler Based on a Conjugated Polymer−Silver Nanoprism Pair for Label-Free Protein Detection

2015 ◽  
Vol 27 (39) ◽  
pp. 6040-6045 ◽  
Author(s):  
Xiaoyu Wang ◽  
Shengliang Li ◽  
Pengbo Zhang ◽  
Fengting Lv ◽  
Libing Liu ◽  
...  
Keyword(s):  
Conjugated Polymer ◽  
Protein Detection ◽  
Label Free ◽  
Free Protein

Protein Detection: An Optical Nanoruler Based on a Conjugated Polymer−Silver Nanoprism Pair for Label-Free Protein Detection (Adv. Mater. 39/2015)

2015 ◽  
Vol 27 (39) ◽  
pp. 6039-6039 ◽  
Author(s):  
Xiaoyu Wang ◽  
Shengliang Li ◽  
Pengbo Zhang ◽  
Fengting Lv ◽  
Libing Liu ◽  
...  
Keyword(s):  
Conjugated Polymer ◽  
Protein Detection ◽  
Label Free ◽  
Free Protein

scholarly journals Label-free protein sensing by employing blue phase liquid crystal

2017 ◽  
Vol 8 (3) ◽  
pp. 1712 ◽  
Author(s):  
Mon-Juan Lee ◽  
Chung-Huan Chang ◽  
Wei Lee
Keyword(s):  
Liquid Crystal ◽  
Label Free ◽  
Protein Sensing ◽  
Free Protein ◽  
Phase Liquid ◽  
Blue Phase
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