Nanotechnology and biosensors

Hierarchical core–shell structure of ZnO nanotube/MnO2 nanosheet arrays on a 3D graphene network as a high performance biosensing platform

A hierarchical core–shell structure composed of ZnO nanotubes/MnO₂ nanosheets was fabricated via a two-step electrochemical deposition procedure on the surface of a 3D graphene network (3DGN) as a free-standing monolithic electrode.

Facile fabrication of amphiphilic AIE active glucan via formation of dynamic bonds: self assembly, stimuli responsiveness and biological imaging

A one-pot strategy has been developed for the preparation of stimuli responsive AIE active glucan through formation of a dynamic Schiff base and a phenyl borate.

The role of solvent polarity in the electronic properties, stability and reactivity trend of a tryptophane/Pd doped SWCNT novel nanobiosensor from polar protic to non-polar solvents

Carbon nanotubes and amino acids have a high potential to offer specific advantages as the transducer and the recognition elements of biosensors.

A biosensor based on gold nanoparticles stabilized in poly(allylamine hydrochloride) and decorated with laccase for determination of dopamine

A new biosensor for dopamine determination based on laccase immobilized in gold nanoparticles is reported.

Recent Advances in Electrochemical Biosensors Based on Fullerene-C60 Nano-Structured Platforms

Nanotechnology is becoming increasingly important in the field of (bio)sensors. The performance and sensitivity of biosensors is greatly improved with the integration of nanomaterials into their construction. Since its first discovery, fullerene-C60 has been the object of extensive research. Its unique and favorable characteristics of easy chemical modification, conductivity, and electrochemical properties has led to its tremendous use in (bio)sensor applications. This paper provides a concise review of advances in fullerene-C60 research and its use as a nanomaterial for the development of biosensors. We examine the research work reported in the literature on the synthesis, functionalization, approaches to nanostructuring electrodes with fullerene, and outline some of the exciting applications in the field of (bio)sensing.

Quartz-Crystal Microbalance (QCM) for Public Health: An Overview of Its Applications

Nanobiotechnologies, from the convergence of nanotechnology and molecular biology and postgenomics medicine, play a major role in the field of public health. This overview summarizes the potentiality of piezoelectric sensors, and in particular, of quartz-crystal microbalance (QCM), a physical nanogram-sensitive device. QCM enables the rapid, real time, on-site detection of pathogens with an enormous burden in public health, such as influenza and other respiratory viruses, hepatitis B virus (HBV), and drug-resistant bacteria, among others. Further, it allows to detect food allergens, food-borne pathogens, such as Escherichia coli and Salmonella typhimurium, and food chemical contaminants, as well as water-borne microorganisms and environmental contaminants. Moreover, QCM holds promises in early cancer detection and screening of new antiblastic drugs. Applications for monitoring biohazards, for assuring homeland security, and preventing bioterrorism are also discussed.

Titanium Dioxide Nanoparticles (TiO₂) Quenching Based Aptasensing Platform: Application to Ochratoxin A Detection

We demonstrate for the first time, the development of titanium dioxide nanoparticles (TiO₂) quenching based aptasensing platform for detection of target molecules. TiO₂ quench the fluorescence of FAM-labeled aptamer (fluorescein labeled aptamer) upon the non-covalent adsorption of fluorescent labeled aptamer on TiO₂ surface. When OTA interacts with the aptamer, it induced aptamer G-quadruplex complex formation, weakens the interaction between FAM-labeled aptamer and TiO₂, resulting in fluorescence recovery. As a proof of concept, an assay was employed for detection of Ochratoxin A (OTA). At optimized experimental condition, the obtained limit of detection (LOD) was 1.5 nM with a good linearity in the range 1.5 nM to 1.0 µM for OTA. The obtained results showed the high selectivity of assay towards OTA without interference to structurally similar analogue Ochratoxin B (OTB). The developed aptamer assay was evaluated for detection of OTA in beer sample and recoveries were recorded in the range from 94.30%–99.20%. Analytical figures of the merits of the developed aptasensing platform confirmed its applicability to real samples analysis. However, this is a generic aptasensing platform and can be extended for detection of other toxins or target analyte.

Iodide sensing via electrochemical etching of ultrathin gold films

Iodide is an essential element for humans and animals and insufficient intake is still a major problem. Affordable and accurate methods are required to quantify iodide concentrations in biological and environmental fluids. A simple and low cost sensing device is presented which is based on iodide induced electrochemical etching of ultrathin gold films. The sensitivity of resistance measurements to film thickness changes is increased by using films with a thickness smaller than the electron mean free path. The underlying mechanism is demonstrated by simultaneous cyclic voltammetry experiments and resistance change measurements in a buffer solution. Iodide sensing is conducted in buffer solutions as well as in lake water with limits of detection in the range of 1 μM (127 μg L(-1)) and 2 μM (254 μg L(-1)), respectively. In addition, nanoholes embedded in the thin films are tested for suitability of optical iodide sensing based on localized surface plasmon resonance.

Green Synthesis of Gold Nanoparticles by a Metal Resistant Arthrobacter nitroguajacolicus Isolated From Gold Mine

Biosynthesis of gold nanoparticles would benefit from the development of clean, nontoxic and environmentally acceptable procedures concerning microorganisms from bacteria to fungi and even algae. Actinobacteria are soil bacteria which have the enormous ability as biotechnological tools. In this paper, we reported the biosynthesis of gold nanoparticles by a member of Arthrobacter genus isolated from Andaliyan gold mine in north-west of Iran. This metal resistance strain obtained from an acidophilic region ( ~ pH 5.6). The UV-vis and XRD spectra of the aqueous medium containing the strain and 1 mM HAuCl 4 for 24 h, demonstrated the formation of gold nanoparticles. TEM micrographs showed intra-extracellular production of gold nanoparticles with spherical shape and average size of 40 nm. The result of morphological and molecular tests revealed that the isolate was belonged to Atrhrobacter and has 100% similarity in 16SrRNA gene sequences to Arthrobacter nitroguajacolicus.

Application of classification models to identify solvents for single-walled carbon nanotubes dispersion

In this study, a list of classification models was developed to categorise organic solvents with respect to their dispersibility of single-walled carbon nanotubes (SWNTs).

Can glycoprofiling be helpful in detecting prostate cancer?

Glycans are chains of carbohydrates attached to proteins (glycoproteins and proteoglycans) or lipids (glycolipids). Glycosylation is a posttranslational modification and glycans have a wide range of functions in a human body including involvement in oncological diseases. Change in a glycan structure cannot only indicate presence of a pathological process, but more importantly in some cases also its stage. Thus, a glycan analysis has a potential to be an effective and reliable tool in cancer diagnostics. Lectins are proteins responsible for natural biorecognition of glycans, even carbohydrate moieties still attached to proteins or whole cells can be recognized by lectins, what makes them an ideal candidate for designing label-free biosensors for glycan analysis. In this review we would like to summarize evidence that glycoprofiling of biomarkers by lectin-based biosensors can be really helpful in detecting prostate cancer.

Marine viruses: the beneficial side of a threat

Marine viruses are ubiquitous, extremely diverse, and outnumber any form of life in the sea. Despite their ecological importance, viruses in marine environments have been largely ignored by the academic community, and only those that have caused substantial economic losses have received more attention. Fortunately, our current understanding on marine viruses has advanced considerably during the last decades. These advances have opened new and exciting research opportunities as several unique structural and genetic characteristics of marine viruses have shown to possess an immense potential for various biotechnological applications. Here, a condensed overview of the possibilities of using the enormous potential offered by marine viruses to develop innovative products in industries as pharmaceuticals, environmental remediation, cosmetics, material sciences, and several others, is presented. The importance of marine viruses to biotechnology should not be underestimated.

Laccase biosensor based on phytic acid modification of nanostructured SiO₂ surface for sensitive detection of dopamine

In this work, three kinds of nanostructured silica-phytic acid (SiO2-PA) materials with diverse morphologies including spherical SiO2-PA (s-SiO2-PA), rod-like (r-SiO2-PA), and helical SiO2-PA (h-SiO2-PA) were prepared with the help of electrostatic interaction. The SiO2-PA nanomaterials with different morphologies were characterized by using transmission electron microscopy (TEM), Fourier transform infrared (FTIR), electrochemical impedance spectroscopy (EIS), and circular dichroism spectrum (CD). Diverse morphologies of SiO2-PA were used as electrode decorated materials to achieve a high efficiency for electrochemical dopamine (DA) detection. The laccase biosensors were fabricated by immobilizing different morphologies of SiO2-PA nanomaterials and laccase onto the glassy carbon electrode (GCE) surface, successively. Then the electrochemical responses of the different morphologies of nanostructured SiO2-PA nanomaterials to laccase were discussed. Results indicated that compared to laccase/s-SiO2-PA and laccase/r-SiO2-PA, the laccase/h-SiO2-PA-modified electrode showed the best electrochemical performances.

Improving the binding efficiency of quartz crystal microbalance biosensors by applying the electrothermal effect

A quartz crystal microbalance (QCM) serving as a biosensor to detect the target biomolecules (analytes) often suffers from the time consuming process, especially in the case of diffusion-limited reaction. In this experimental work, we modify the reaction chamber of a conventional QCM by integrating into the multi-microelectrodes to produce electrothermal vortex flow which can efficiently drive the analytes moving toward the sensor surface, where the analytes were captured by the immobilized ligands. The microelectrodes are placed on the top surface of the chamber opposite to the sensor, which is located on the bottom of the chamber. Besides, the height of reaction chamber is reduced to assure that the suspended analytes in the fluid can be effectively drived to the sensor surface by induced electrothermal vortex flow, and also the sample costs are saved. A series of frequency shift measurements associated with the adding mass due to the specific binding of the analytes in the fluid flow and the immobilized ligands on the QCM sensor surface are performed with or without applying electrothermal effect (ETE). The experimental results show that electrothermal vortex flow does effectively accelerate the specific binding and make the frequency shift measurement more sensible. In addition, the images of the binding surfaces of the sensors with or without applying electrothermal effect are taken through the scanning electron microscopy. By comparing the images, it also clearly indicates that ETE does raise the specific binding of the analytes and ligands and efficiently improves the performance of the QCM sensor.

Optical and dielectric sensors based on antimicrobial peptides for microorganism diagnosis

Antimicrobial peptides (AMPs) are natural compounds isolated from a wide variety of organisms that include microorganisms, insects, amphibians, plants, and humans. These biomolecules are considered as part of the innate immune system and are known as natural antibiotics, presenting a broad spectrum of activities against bacteria, fungi, and/or viruses. Technological innovations have enabled AMPs to be utilized for the development of novel biodetection devices. Advances in nanotechnology, such as the synthesis of nanocomposites, nanoparticles, and nanotubes have permitted the development of nanostructured platforms with biocompatibility and greater surface areas for the immobilization of biocomponents, arising as additional tools for obtaining more efficient biosensors. Diverse AMPs have been used as biological recognition elements for obtaining biosensors with more specificity and lower detection limits, whose analytical response can be evaluated through electrochemical impedance and fluorescence spectroscopies. AMP-based biosensors have shown potential for applications such as supplementary tools for conventional diagnosis methods of microorganisms. In this review, conventional methods for microorganism diagnosis as well new strategies using AMPs for the development of impedimetric and fluorescent biosensors are highlighted. AMP-based biosensors show promise as methods for diagnosing infections and bacterial contaminations as well as applications in quality control for clinical analyses and microbiological laboratories.

Surfactants present complex joint effects on the toxicities of metal oxide nanoparticles

The potential toxicities of nanoparticles (NPs) have been intensively discussed over the past decade. In addition to their single toxicities, NPs can interact with other environmental chemicals and thereby exert joint effects on biological systems and the environment. The present study investigated the combined toxicities of NPs and surfactants, which are among the chemicals that most likely coexist with NPs. Photobacterium phosphoreum was employed as the model organism. The results indicate that surfactants with different ion types can alter the properties of NPs (i.e., particle size and surface charge) in different ways and present complex joint effects on NP toxicities. Mixtures of different NPs and surfactants exhibited antagonistic, synergistic, and additive effects. In particular, the toxicity of ZnO was observed to result from its dissolved Zn(2+); thus, the joint effects of the ZnO NPs and surfactants can be explained by the interactions between the Zn ions and the surfactants. Our study suggests that the potential hazards caused by mixtures of NPs and surfactants are different from those caused by single NPs. Because surfactants are extensively used in the field of nanotechnology and are likely to coexist with NPs in natural waters, the ecological risk assessments of NPs should consider the impacts of surfactants.

Zinc Oxide-From Synthesis to Application: A Review

Zinc oxide can be called a multifunctional material thanks to its unique physical and chemical properties. The first part of this paper presents the most important methods of preparation of ZnO divided into metallurgical and chemical methods. The mechanochemical process, controlled precipitation, sol-gel method, solvothermal and hydrothermal method, method using emulsion and microemulsion enviroment and other methods of obtaining zinc oxide were classified as chemical methods. In the next part of this review, the modification methods of ZnO were characterized. The modification with organic (carboxylic acid, silanes) and inroganic (metal oxides) compounds, and polymer matrices were mainly described. Finally, we present possible applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis were introduced. This review provides useful information for specialist dealings with zinc oxide.

Self-assembly of 50 bp poly(dA)·poly(dT) DNA on highly oriented pyrolytic graphite via atomic force microscopy observation and molecular dynamics simulation

This study has investigated the formation patterns resulting from the self-assembly of deoxyribonucleic acid (DNA) on highly oriented pyrolytic graphite (HOPG), using both experimental and molecular dynamics approaches. Under optimized conditions based on pretreatment of HOPG surface and specific solution concentrations, DNA is found to self-assemble to form various patterned networks. The associated self-assembly mechanism is elucidated using coarse-grained molecular dynamics simulations and fractal dimension analysis. The results of this work demonstrate an effective technique allowing the formation of arrays of negatively charged biomacromolecules on negatively charged HOPG surfaces.

Nanopore integrated nanogaps for DNA detection

A high-throughput fabrication of sub-10 nm nanogap electrodes combined with solid-state nanopores is described. These devices should allow concomitant tunneling and ionic current detection of translocating DNA molecules. We report the optimal fabrication parameters in terms of dose, resist thickness, and gap shape that allow easy reproduction of the fabrication process at wafer scale. The device noise and current voltage characterizations performed and the influence of the nanoelectrodes on the ionic current noise is identified. In some cases, ionic current rectification for connected or biased nanogap electrodes is also observed. In order to increase the extremely low translocation rates, several experimental strategies were tested and modeled using finite element analysis. Our findings are useful for future device designs of nanopore integrated electrodes for DNA sequencing.

Nanobiosensors: Concepts and Variations

Biosensing has been one of the hottest topic attracting scientific minds since long back. It is so as biological entities are very complex and are directly associated with the existence of a healthy environment. The design of biosensors also has witnessed significant changes in the recent past. Biosensors for applications as diverse as food quality estimation, environmental monitoring, and diagnosis of clinical and metabolic complications have come to the fore. Nanotechnology has bestowed some highly exciting ingredients for the improvement of sensing phenomenon. The use of diverse nanomaterials ranging from nanoparticles, nanotubes, nanorods, and nanowires has enabled faster detection and its reproducibility in a much better way. The unique properties of nanomaterials such as high electrical conductivity, better shock bearing ability, and the sensitive responses such as piezoelectric and versatile color based detection mechanisms are only the results of congregation of nanomaterial properties. This paper highlights the different types of biosensors based on different types of nanomaterials and their developmental and implicational aspects.

Gold, Silver and Platinum Nanoparticles Biosynthesized Using Orange Peel Extract

Nowadays, metal nanoparticles have attracted a great scientific interest due to their unique optoelectronic and physicochemical properties with applications in diverse areas such as molecular diagnostics and drug delivery, electronics, catalysis or sensing. The development of techniques for the controlled synthesis of nanoparticles of well defined size, shape and composition has become a big challenge. Development of reliable and eco-friendly processes for synthesis of metallic nanoparticles is an important step in the field of applied nanotechnology. The use of biological systems as factories to produce nanoparticles is one way to achieve this objective. This study reports the synthesis of different metallic nanoparticles (gold, silver and platinum) through reduction of metal precursors by the extract of orange peel. It also demonstrates that particle size and shape could be controlled by varying parameters such as pH.

A methodological combined framework for roadmapping biosensor research: a fault tree analysis approach within a strategic technology evaluation frame

Biosensor technology began in the 1960s to revolutionize instrumentation and measurement. Despite the glucose sensor market success that revolutionized medical diagnostics, and artificial pancreas promise currently the approval stage, the industry is reluctant to capitalize on other relevant university-produced knowledge and innovation. On the other hand, the scientific literature is extensive and persisting, while the number of university-hosted biosensor groups is growing. Considering the limited marketability of biosensors compared to the available research output, the biosensor field has been used by the present authors as a suitable paradigm for developing a methodological combined framework for "roadmapping" university research output in this discipline. This framework adopts the basic principles of the Analytic Hierarchy Process (AHP), replacing the lower level of technology alternatives with internal barriers (drawbacks, limitations, disadvantages), modeled through fault tree analysis (FTA) relying on fuzzy reasoning to count for uncertainty. The proposed methodology is validated retrospectively using ion selective field effect transistor (ISFET) - based biosensors as a case example, and then implemented prospectively membrane biosensors, putting an emphasis on the manufacturability issues. The analysis performed the trajectory of membrane platforms differently than the available market roadmaps that, considering the vast industrial experience in tailoring and handling crystallic forms, suggest the technology path of biomimetic and synthetic materials. The results presented herein indicate that future trajectories lie along with nanotechnology, and especially nanofabrication and nano-bioinformatics, and focused, more on the science-path, that is, on controlling the natural process of self-assembly and the thermodynamics of bioelement-lipid interaction. This retained the nature-derived sensitivity of the biosensor platform, pointing out the differences between the scope of academic research and the market viewpoint.

Cascadic multienzyme reaction-based electrochemical biosensors

: Since the first glucose biosensor was developed by Clark and Lyons, there have been great efforts to develop effective enzyme biosensors for wide applications. Those efforts are closely related to the enhancement of biosensor performance, including sensitivity improvement, elevation of selectivity, and extension of the range of analytes that may be determined. Introduction of a cascadic multienzyme reaction to the electrochemical biosensor is one of those efforts. By employing more than two enzymes to the biosensor, its sensitivity and accuracy can be enhanced. Also, the narrow application range that is a typical limitation of single enzyme-based biosensor can be overcome. This chapter will discuss the fundamental principles for the development of cascadic multienzyme reaction-based electrochemical biosensors and their applications in clinical and environmental fields.

Cholesterol--a biological compound as a building block in bionanotechnology

Cholesterol is a molecule with many tasks in nature but also a long history in science. This feature article highlights the contribution of this small compound to bionanotechnology. We discuss relevant chemical aspects in this context followed by an overview of its self-assembly capabilities both as a free molecule and when conjugated to a polymer. Further, cholesterol in the context of liposomes is reviewed and its impact ranging from biosensing to drug delivery is outlined. Cholesterol is and will be an indispensable player in bionanotechnology, contributing to the progress of this potent field of research.

Aptamer-modified nanoparticles as biosensors

Aptamers are short oligonucleotides that are capable of selectively binding to their corresponding target. Therefore, they can be thought of as a nucleic acid-based alternative to antibodies and can substitute for their amino acid-based counterparts in analytical applications, including as receptors in biosensors. Here they offer several advantages because their nucleic acid nature and their binding via an induced fit mechanism enable novel sensing strategies. In this article, the utilization of aptamers as novel bio-receptors in combination with nanoparticles as transducer elements is reviewed. In addition to these analytical applications, the medical relevance of aptamer-modified nanoparticles is described.

Modified gold surfaces by 6-(ferrocenyl)hexanethiol/dendrimer/gold nanoparticles as a platform for the mediated biosensing applications

An electrochemical biosensor mediated by using 6-(Ferrocenyl) hexanethiol (FcSH) was fabricated by construction of gold nanoparticles (AuNPs) on the surface of polyamidoamine dendrimer (PAMAM) modified gold electrode. Glucose oxidase (GOx) was used as a model enzyme and was immobilized onto the gold surface forming a self assembled monolayer via FcSH and cysteamine. Cyclic voltammetry and amperometry were used for the characterization of electrochemical response towards glucose substrate. Following the optimization of medium pH, enzyme loading, AuNP and FcSH amount, the linear range for the glucose was studied and found as 1.0 to 5.0mM with the detection limit (LOD) of 0.6mM according to S/N=3. Finally, the proposed Au/AuNP/(FcSH+Cyst)/PAMAM/GOx biosensor was successfully applied for the glucose analysis in beverages, and the results were compared with those obtained by HPLC.

Direct characterization of native chemical ligation of peptides on silicon nanowires

We describe the site-specific and chemoselective immobilization of peptides on hydrogen-terminated silicon nanowires (SiNWs) using native chemical ligation (NCL) (i.e., the reaction of a thioester group with a cysteine moiety to give a stable amide bond). The SiNWs investigated in this work were grown via a vapor-liquid-solid mechanism and functionalized with a thioester moiety. The immobilization of the peptides on the SiNWs was demonstrated by synthesizing peptides with an N-terminal cysteine residue and labeled with tetramethylrhodamine or trifluoromethyl groups that were detected by fluorescence and X-ray photoelectron spectroscopy, respectively. The peptides labeled with tetramethylrhodamine or trifluoromethyl groups for fluorescence or X-ray photoelectron spectroscopy (XPS) detection studies were synthesized with an N-terminal cysteine residue. N-Terminal seryl peptides and carboxy-terminated SiNWs were used as controls to demonstrate the chemoselectivity of the peptide immobilization.

Biosensors - classification, characterization and new trends

Biosensors represent promising analytical tools applicable in areas such as clinical diagnosis, food industry, environment monitoring and in other fields, where rapid and reliable analyses are needed. Some biosensors were successfully implemented in the commercial sphere, but majority needs to be improved in order to overcome some imperfections. This review covers the basic types, principles, constructions and use of biosensors as well as new trends used for their fabrication.