scholarly journals One-Step Fabrication of Stimuli-Responsive Chitosan-Platinum Brushes for Listeria monocytogenes Detection

Biosensors ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 511
Author(s):  
Daniela A. Oliveira ◽  
Suleiman Althawab ◽  
Eric S. McLamore ◽  
Carmen L. Gomes
Keyword(s):  
Listeria Monocytogenes ◽  
Surface Area ◽  
Limit Of Detection ◽  
Food Product ◽  
Critical Issue ◽  
Label Free ◽  
Stimuli Responsive ◽  
Chicken Broth ◽  
One Step ◽  
Electroactive Surface Area

Bacterial contamination in food-processing facilities is a critical issue that leads to outbreaks compromising the integrity of the food supply and public health. We developed a label-free and rapid electrochemical biosensor for Listeria monocytogenes detection using a new one-step simultaneous sonoelectrodeposition of platinum and chitosan (CHI/Pt) to create a biomimetic nanostructure that actuates under pH changes. The XPS analysis shows the effective co-deposition of chitosan and platinum on the electrode surface. This deposition was optimized to enhance the electroactive surface area by 11 times compared with a bare platinum–iridium electrode (p < 0.05). Electrochemical behavior during chitosan actuation (pH-stimulated osmotic swelling) was characterized with three different redox probes (positive, neutral, and negative charge) above and below the isoelectric point of chitosan. These results showed that using a negatively charged redox probe led to the highest electroactive surface area, corroborating previous studies of stimulus–response polymers on metal electrodes. Following this material characterization, CHI/Pt brushes were functionalized with aptamers selective for L. monocytogenes capture. These aptasensors were functional at concentrations up to 106 CFU/mL with no preconcentration nor extraneous reagent addition. Selectivity was assessed in the presence of other Gram-positive bacteria (Staphylococcus aureus) and with a food product (chicken broth). Actuation led to improved L. monocytogenes detection with a low limit of detection (33 CFU/10 mL in chicken broth). The aptasensor developed herein offers a simple fabrication procedure with only one-step deposition followed by functionalization and rapid L. monocytogenes detection, with 15 min bacteria capture and 2 min sensing.

A comparative study of graphene–hydrogel hybrid bionanocomposites for biosensing

The Analyst ◽  
2015 ◽  
Vol 140 (5) ◽  
pp. 1466-1476 ◽  
Author(s):  
S. L. Burrs ◽  
D. C. Vanegas ◽  
M. Bhargava ◽  
N. Mechulan ◽  
P. Hendershot ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Comparative Study ◽  
Response Time ◽  
Surface Area ◽  
Silk Fibroin ◽  
Cellulose Nanocrystals ◽  
Limit Of Detection ◽  
Enzymatic Biosensors ◽  
The Comparative Study ◽  
Electroactive Surface Area

Graphene–nanometal enzymatic biosensors were prepared using hydrogels composed of chitosan, poly-N-isopropylacrylamide, silk fibroin, or cellulose nanocrystals. The comparative study investigated electroactive surface area, charge transfer, response time, limit of detection, and sensitivity toward alcohols.

scholarly journals Label Free Biosensor Methods in Detection of Food Pathogens and Listeria monocytogenes

2017 ◽  
Author(s):  
Rajeswaran Radhakrishnan ◽  
Palmiro Poltronieri
Keyword(s):  
Surface Plasmon Resonance ◽  
Electrochemical Impedance Spectroscopy ◽  
Listeria Monocytogenes ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Liquid Food ◽  
Label Free ◽  
Food Matrix ◽  
Food Pathogens

Food pathogens contaminate food products that allow their growth on the shelf and also under refrigerated conditions. Therefore, it is of utmost importance to lower the limit of detection (LOD) of the method used and to obtain the results within hours to few days. Biosensor methods exploit the available technologies to individuate and provide an approximate quantification of the bacteria present in a sample. The main bottleneck of these methods depend on the aspecific binding to the surfaces and on a change in sensitivity when bacteria are in a complex food matrix in respect to bacteria in a liquid food sample. In this review we introduce Surface Plasmon Resonance (SPR), new advancements in SPR techniques, and Electrochemical Impedance Spectroscopy (EIS), as label-free biosensing technologies for the detection of L. monocytogenes in foods. The application of the two methods has made possible the detection of L. monocytogenes with LOD of 1 log CFU/mL. Further advancement are envisaged through the combination of biosensor methods with immunoseparation of bacteria from larger volumes.

scholarly journals Electrochemical nano-roughening of gold microstructured electrodes for the enhanced detection of copper and glucose

2021 ◽  
Author(s):  
Eduardo Gonzalez Martinez ◽  
Sokunthearath (Kevin) Saem ◽  
Nadine Beganovic ◽  
Jose Moran-Mirabal
Keyword(s):  
Surface Area ◽  
Limit Of Detection ◽  
Film Surface ◽  
High Sensitivity ◽  
Cost Effective ◽  
Progressive Increase ◽  
Gold Electrodes ◽  
Limit Of Quantification ◽  
Thin Film Surface ◽  
Electroactive Surface Area

One of the main challenges for electrochemical sensor miniaturization is the fabrication of electrodes with a smaller footprint, while maintaining, or even increasing, their sensitivity for the targeted application. Our research group has previously demonstrated the enhancement of the electroactive surface area of gold electrodes up to 6-fold, relative to planar gold electrodes with the same footprint, through the generation of a wrinkled thin film surface via thermal shrinking. In this work, the electroactive surface area of wrinkled gold electrodes was further enhanced up to 5-fold (30-fold over flat electrodes) using a chronoamperometric pulsing technique. Scanning electron microscopy images showed progressive increase of surface roughness in response to an increasing number of applied pulses. The resulting nanoroughened electrodes present several advantages in addition to the enhanced electroactive surface area. These electrodes offer superior fouling resistance compared to that of wrinkled and flat electrodes when submerged in a solution containing bovine serum albumin at high concentrations. Cyclic voltammetry data also revealed greater sensitivity of nanoroughened electrodes toward anodic copper stripping, where the limit of quantification of copper by the nano-roughened electrodes was 0.3 ppm. Nano-roughened electrodes also allowed the highly sensitive enzyme-free detection of glucose through chronoamperometry, with a limit of detection of 0.5 mM, whereas planar electrodes did not demonstrate any ability to oxidize glucose. We foresee that this methodology to fabricate nanostructured electrodes will accelerate the development of simple, cost-effective and high sensitivity electrochemical platforms.

scholarly journals Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 4
Author(s):  
Donggee Rho ◽  
Seunghyun Kim
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Sample Volume ◽  
Small Sample ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Cavity Structure

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

One-step fast and label-free imaging array for multiplexed detection of trace avian influenza viruses

2021 ◽  
pp. 338645
Author(s):  
Dagang Jiang ◽  
Yafei Tian ◽  
Yujiao Zhang ◽  
Xueyun Lu ◽  
Dan Xiao ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Influenza Viruses ◽  
Label Free ◽  
Avian Influenza Viruses ◽  
Multiplexed Detection ◽  
Imaging Array ◽  
One Step

scholarly journals Surface Plasmon Resonance Assay for Label-Free and Selective Detection of HIV-1 p24 Protein

Biosensors ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 180
Author(s):  
Lucia Sarcina ◽  
Giuseppe Felice Mangiatordi ◽  
Fabrizio Torricelli ◽  
Paolo Bollella ◽  
Zahra Gounani ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Covalent Binding ◽  
Hiv Infections ◽  
Selectivity Ratio ◽  
Selective Detection ◽  
Label Free ◽  
Self Assembled Monolayer ◽  
Label Free Detection ◽  
P24 Protein ◽  
Hiv 1

The early detection of the human immunodeficiency virus (HIV) is of paramount importance to achieve efficient therapeutic treatment and limit the disease spreading. In this perspective, the assessment of biosensing assay for the HIV-1 p24 capsid protein plays a pivotal role in the timely and selective detection of HIV infections. In this study, multi-parameter-SPR has been used to develop a reliable and label-free detection method for HIV-1 p24 protein. Remarkably, both physical and chemical immobilization of mouse monoclonal antibodies against HIV-1 p24 on the SPR gold detecting surface have been characterized for the first time. The two immobilization techniques returned a capturing antibody surface coverage as high as (7.5 ± 0.3) × 1011 molecule/cm2 and (2.4 ± 0.6) × 1011 molecule/cm2, respectively. However, the covalent binding of the capturing antibodies through a mixed self-assembled monolayer (SAM) of alkanethiols led to a doubling of the p24 binding signal. Moreover, from the modeling of the dose-response curve, an equilibrium dissociation constant KD of 5.30 × 10−9 M was computed for the assay performed on the SAM modified surface compared to a much larger KD of 7.46 × 10−5 M extracted for the physisorbed antibodies. The chemically modified system was also characterized in terms of sensitivity and selectivity, reaching a limit of detection of (4.1 ± 0.5) nM and an unprecedented selectivity ratio of 0.02.

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.

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