Electrochemical Detection of Different Foodborne Bacteria for Point-of-Care Applications.

Bacterial infections resulting from foodborne pathogenic bacteria cause millions of infections that greatly threaten human health and are one of the leading causes of mortality around the world. To counter this, the early, rapid, and accurate detection of bacterial infections is very important to address serious health issue concerns. We, therefore, present an electrochemical biosensor based on aptamers that selectively bind with the DNA of specific bacteria for the accurate and rapid detection of various foodborne bacteria for the selective determination of bacterial infection types.

Recent Trends in Metal Nanoparticles Decorated 2D Materials for Electrochemical Biomarker Detection.

Technological advancements in the healthcare sector have pushed for improved sensors and devices for disease diagnosis and treatment. Recently, with the discovery of numerous biomarkers for various specific physiological conditions, early disease screening has become a possibility. Biomarkers are the body's early warning systems, which are indicators of a biological state that provides a standardized and precise way of evaluating the progression of disease or infection.

RGO-PANI composite Au microelectrodes for sensitive ECIS analysis of human gastric (MKN-1) cancer cells.

Microelectrode-based cell chip studies for cellular responses often require improved adhesion and growth conditions for efficient cellular diagnosis and high throughput screening in drug discovery. Cell-chip studies are often performed on gold electrodes due to their biocompatibility, and stability, but the electrode-electrolyte interfacial capacitance is the main drawback to the overall sensitivity of the detection system. Thus, here, we developed reduced graphene oxide-polyaniline-modified gold microelectrodes for real-time impedance-based monitoring of human gastric adenocarcinoma cancer (MKN-1) cells.

Conformationally Flexible Dimeric-Serotonin-Based Sensitive and Selective Electrochemical Biosensing Strategy for Serotonin Recognition.

A novel electrochemical sensor was constructed based on an enzyme-mediated physiological reaction between neurotransmitter serotonin per-oxidation to reconstruct dual-molecule 4,4'-dimeric-serotonin self-assembled derivative, and the potential biomedical application of the multi-functional nano-platform was explored. Serotonin accelerated the catalytic activity to form a dual molecule at the C4 position and created phenolic radical-radical coupling intermediates in a peroxidase reaction system. Here, 4,4' dimeric-serotonin possessed the capability to recognize intermolecular interactions between amine groups.

Recombinant Histidine-Tagged Nano-protein-based Highly Sensitive Electro-Sensing Device for Salivary Cortisol.

We have developed a powerful biosensing strategy for immobilizing histidine-tagged (His-Tag)-oriented recombinant nano-protein immobilization on a chemically modified glassy carbon electrode (GCE) surfaces via (S)-N-(5-amino-1-carboxypentyl)iminodiacetic acid (ANTA) acting as a chelating Ni centered interaction. Here, we introduce a label-free electro-sensor to quantify cortisol levels in saliva samples for point-of-care testing (POCT). The high specificity of the chemically modified GCE was established by genetically bio-engineered metal-binding sites on the selected recombinant apoferritin (R-AFTN) nano-protein to impart functionality to its surface and by coating the carbon surface with the self-assembled monolayers of 4-aminobenzoic acid (4-ABA) attached to ANTA groups complexed with Ni transition metal ions.

Polypyrrole-palladium nanocomposite as a high-efficiency transducer for thrombin detection with liposomes as a label.

Sensitive and selective determination of protein biomarkers with high accuracy often remains a great challenge due to their existence in the human body at an exceptionally low concentration level. Therefore, sensing mechanisms that are easy to use, simple, and capable of accurate quantification of analyte are still in development to detect biomarkers at a low concentration level. To meet this end, we demonstrated a methodology to detect thrombin in serum at low concentration levels using polypyrrole (PPy)-palladium (Pd)nanoparticle-based hybrid transducers using liposomes encapsulated redox marker as a label.

Dimeric-serotonin bivalent ligands induced gold nanoparticle aggregation for highly sensitive and selective serotonin biosensor.

Chemically modulating monoamine neurotransmitter serotonin undergoes a physiological reaction of enzyme intermediated peroxidation to reconstruct dimeric self-assembled complex. A standard bivalent ligand approach dimeric serotonin increases structural and functional scaffolding with recognition-binding sites that are fundamentally more friendly than monovalent binding sites. Dimerization reaction accelerates the catalytic activity of one-electron oxidation at the C(4) position of serotonin to generate dual phenolic radicals in the presence of horseradish (HRP) and hydrogen peroxide (HO).

Bioelectrocatalysis of Hemoglobin on Electrodeposited Ag Nanoflowers toward HO Detection.

Hydrogen peroxide (HO) is a partially reduced metabolite of oxygen that exerts a diverse array of physiological and pathological activities in living organisms. Therefore, the accurate quantitative determination of HO is crucial in clinical diagnostics, the food industry, and environmental monitoring. Herein we report the electrosynthesis of silver nanoflowers (AgNFs) on indium tin oxide (ITO) electrodes for direct electron transfer of hemoglobin (Hb) toward the selective quantification of HO.

Laser-induced graphene interdigitated electrodes for label-free or nanolabel-enhanced highly sensitive capacitive aptamer-based biosensors.

Highly porous laser-induced graphene (LIG) is easily generated in complex electrode configurations such as interdigitated electrodes (IDEs). Here, we demonstrate that their superior capacitive response at low frequencies can be exploited in affinity biosensors using thrombin aptamers as model biorecognition elements. Of specific interest was the effect of electrode surface area on capacitance detection, and the comparison between a label-free format and enhancement strategies afforded by carboxy group bearing polymeric nanoparticles or liposomes.

Nanostructured Au-Pt hybrid disk electrodes for enhanced parathyroid hormone detection in human serum.

Most clinical tests for biomarker detection require the support of a laboratory, and the results are usually slow, less sensitive, and lack the possibility for Point-of-Care (PoC) testing. Further, with the increasing demand for sensitive, portable, rapid, and low-cost devices for clinical PoC applications, innovative methods are crucial. Thus, we report on utilizing nanostructured gold-platinum (Au-Pt) hybrid electrodes as a PoC device for highly sensitive and selective PTH detection in human serum samples.

Robust Bioengineered Apoferritin Nanoprobes for Ultrasensitive Detection of Infectious Pancreatic Necrosis Virus.

Infectious pancreatic necrosis virus (IPNV) has been identified as a viral pathogen for many fish diseases that have become a huge hurdle for the growing fishing industry. Thus, in this work, we report a label-free impedance biosensor to quantify IPNV in real fish samples at point-of-care (POC) level. High specificity IPNV sensor with a detection limit of 2.

Label-Free Impedance Sensing of Aflatoxin B₁ with Polyaniline Nanofibers/Au Nanoparticle Electrode Array.

Aflatoxin B (AFB₁) is produced by the and group of fungi which is most hepatotoxic and hepatocarcinogenic and occurs as a contaminant in a variety of foods. AFB₁ is mutagenic, teratogenic, and causes immunosuppression in animals and is mostly found in peanuts, corn, and food grains. Therefore, novel methodologies of sensitive and expedient strategy are often required to detect mycotoxins at the lowest level.

Electrochemical immunosensor for highly sensitive and quantitative detection of tumor necrosis factor-α in human serum.

Highly sensitive and selective biosensors for accurate determination of specific protein biomarkers at low levels in serum are a prerequisite for the present healthcare systems. Therefore, here we developed a label-free impedimetric method for tumor necrosis factor-alpha (TNF-α) detection using reduced graphene oxide (RGO) with gold nanoparticles (AuNP) on an indium tin oxide (ITO) microdisk electrodes. The detection mechanism relies on resistance change occurs due to [Fe(CN)] redox probe movement towards the conductive channels of the AuNP-RGO films gated by the recognition of the target biomarker by its anti-TNF-α antibody.

Azurin/CdSe-ZnS-Based Bio-Nano Hybrid Structure for Nanoscale Resistive Memory Device.

In the present study, we propose a method for bio-nano hybrid formation by coupling a redox metalloprotein, Azurin, with CdSe-ZnS quantum dot for the development of a nanoscale resistive memory device. The covalent interaction between the two nanomaterials enables a strong and effective binding to form an azurin/CdSe-ZnS hybrid, and also enabled better controllability to couple with electrodes to examine the memory function properties. Morphological and optical properties were performed to confirm both hybrid formations and also their individual components.

Recombinant azurin-CdSe/ZnS hybrid structures for nanoscale resistive random access memory device.

In the present study, we developed a biohybrid material composed of recombinant azurin and CdSe-ZnS quantum dot to perform as a resistive random access memory (ReRAM) device. Site specific amino acid sequences were introduced in azurin to bind with the surface of CdSe-ZnS nanoparticle allowing the formation of a hybrid and voltage-driven switching enabled to develop a resistive random access memory (ReRAM) device. The analytical measurements confirmed that the azurin and CdSe-ZnS nanoparticles were well conjugated and formed into a single hybrid.

Silver nanoflower-reduced graphene oxide composite based micro-disk electrode for insulin detection in serum.

Sensitive and selective determination of protein biomarkers remains a significant challenge due to the existence of various biomarkers in human body at a low concentration level. Therefore, new technologies were incessantly steered to detect tiny biomarkers at a low concentration level, yet, it is difficult to develop reliable, stable and sensitive detection methods for disease diagnostics. Therefore, the present study demonstrates a methodology to detect insulin in serum at low levels based on Ag nanoflower (AgNF) decorated reduced graphene oxide (rGO) modified micro-disk electrode arrays (MDEAs).

Reduced Graphene Oxide Modified the Interdigitated Chain Electrode for an Insulin Sensor.

Insulin is a key regulator in glucose homeostasis and its deficiency or alternations in the human body causes various types of diabetic disorders. In this paper, we present the development of a reduced graphene oxide (rGO) modified interdigitated chain electrode (ICE) for direct capacitive detection of insulin. The impedance properties of rGO-ICE were characterized by equivalent circuit modeling.

Electrochemical Characterization of Poly-L-Lysine Coating on Indium Tin Oxide Electrode for Enhancing Cell Adhesion.

Nano or microelectrode-based cell chip for stimulating or recording neuronal signals requires better cell adhesion procedures in order to achieve efficient cell based assays for effective cellular diagnosis and for high throughput screening of drug candidates. The cells can be adhered on protein pre-coated sensing electrodes, but the electrochemical characteristics of cells are highly influenced by the electrical charge of the underlying protein interface. Thus, in this study, we report on experimental and theoretical aspects of poly-L-lysine (PLL) adsorption on transparent indium tin oxide (ITO) electrodes and the interaction between PLL and human embryonic kidney 293/GFP cells.

Label-free and direct detection of C-reactive protein using reduced graphene oxide-nanoparticle hybrid impedimetric sensor.

For label-free and direct detection of C-reactive protein (CRP), an impedimetric sensor based on an indium tin oxide (ITO) electrode array functionalized with reduced graphene oxide-nanoparticle (rGO-NP) hybrid was fabricated and evaluated. Analytical measurements were performed to examine the properties of rGO-NP-modified ITO microelectrodes and to determine the influence upon sensory performance of using nanostructures modified for antibody immobilization and for recognition of CRP binding events. Impedimetric measurements in the presence of the redox couple [Fe(CN)6](3-/4-) showed significant changes in charge transfer resistance upon binding of CRP.

Construction of RNA-Quantum Dot Chimera for Nanoscale Resistive Biomemory Application.

RNA nanotechnology offers advantages to construct thermally and chemically stable nanoparticles with well-defined shape and structure. Here we report the development of an RNA-QD (quantum dot) chimera for resistive biomolecular memory application. Each QD holds two copies of the pRNA three-way junction (pRNA-3WJ) of the bacteriophage phi29 DNA packaging motor.

An electrochemical H2O2 detection method based on direct electrochemistry of myoglobin immobilized on gold deposited ITO electrode.

A protein based electrochemical sensor for the detection of hydrogen peroxide based on Myoglobin immobilized on gold nano structures patterned on Indium tin oxide electrode was developed. A uniformly distributed nanometer sized Au-array on ITO electrode surface was obtained by optimizing electro deposition conditions. The morphology of Mb molecules and Au-nanostructures on ITO was investigated by scanning electron microscopy.

An enzymatic biosensor for hydrogen peroxide based on CeO2 nanostructure electrodeposited on ITO surface.

In this study, an enzymatic biosensor for amperometric detection of hydrogen peroxide was developed based on the direct electrochemistry of myoglobin (Mb) on a porous cerium dioxide (CeO2) nanostructured film. The developed film accomplished with large surface area was electrodeposited on an indium tin oxide (ITO) substrate. Surface morphological studies revealed that the formed CeO2 film has a large specific surface area with a unique nanostructure on the ITO surface.

Electrochemical cell chip to detect environmental toxicants based on cell cycle arrest technique.

A cell-based chip was recently developed and shown to be an effective in vitro tool for analyzing effect of environmental toxin on target cells. However, common cell chips are inappropriate for the detection of multiple environmental toxins. Here, we fabricated a neural cell chip to detect different cellular responses induced by BPA (bisphenol-A) and PCB (poly chlorinated biphenyl).

A robust nanoscale biomemory device composed of recombinant azurin on hexagonally packed Au-nano array.

We developed a nanoscale memory device consisting of signal-responsive biomaterial, which is capable of switching physical properties (such as electrical/electrochemical, optical, and magnetic) upon application of appropriate electrical signals to perform memory switching. Here, we propose a highly robust surface-confined switch composed of an electroactive cysteine-modified azurin immobilized on an Au hexagonal pattern formed on indium tin oxide (ITO) substrates that can be controlled electrochemically and reversibly converted between its redox states. The memory effect is based on conductance switching, which leads to the occurrence of bistable states and behaves as an extremely robust redox switch in which an electrochemical input is transduced into optical and magnetic outputs under ambient conditions.

Electrochemical performance of gold nanoparticle-cytochrome c hybrid interface for H2O2 detection.

Here, we describe the formation of a hybrid biointerface consisting of gold nanoparticle (AuNP) and cytochrome c (cyt c) on indium tin oxide (ITO) electrodes using a two-step immobilization procedure. The Au nanoparticles were attached to the ITO electrodes by 3-mercaptopropyl trimethoxysilane (3-MPTMS). The electrode was then incubated with 11-mercapundecanoic acid (11-MUA) and the nanoparticles were activated to allow for coupling to cyt c.