Procedia Technology最新文献

We demonstrate a magnesium zinc oxide (MZO) nanostructure-modified quartz crystal microbalance (MZO_nano-QCM) biosensor to dynamically monitor antimicrobial effects on E. coli and S. cerevisiae. The MZO nanostructures were grown on the top electrode of a standard QCM using metal-organic chemical-vapor deposition (MOCVD). The MZO nanostructures are utilized as the sensing material due to their multifunctionality, biocompatibility, and very large effective sensing surface. The MZO surface-wettability and morphology are controlled, offering high-sensitivity to various biological/biochemical species. The MZO_nano-QCM was applied to detect the effects of ampicillin and tetracycline on sensitive and resistant strains of E.coli, as well as effects of amphotericin-B and miconazole on S. cerevisiae through the device's time-dependent frequency shift and motional resistance.

The small molecules detection remains a challenge for diagnostics. Due to their size, difficulties arise in finding selective and sensitive probes as well as developing appropriate detection format based on sandwich and/or signal amplification assays. In this study, we combine multiple strategies: a) the use of aptamer probes, short oligonucleotides strands selected in order to present strong selectivity for the small molecule target, b) the sequence engineering of split versions of the aptamer for a sandwich assay and c) the amplification of Surface Plasmon Resonance imaging (SPRi) signal by the use of gold nanoparticles (AuNPs). Combining those three strategies lead to state-of-the-art limit of detection (LOD = 50 nM) for the adenosine target.

Flight vehicles can soar around Earth via ejecting the combusted gases in the space and bio-molecular motor proteins possess the ability to walk along the tracts through hydrolyzing adenosine triphosphate (ATP) in cells. Inspired by flight vehicles and naturally occurring bio-molecular protein motors, miniaturized disk-like nanoswimmers are proposed, which are composed of three different metals: gold (Au), nickel (Ni), and platinum (Pt). The proposed nanoswimmers are fabricated via a layer-by-layer deposition method base on nano-electro-mechanical systems (NEMS) technology, whereby Pt functions as the chemical catalyst for the decomposition of hydrogen peroxide (H₂O₂) to produce oxygen (O₂) bubbles detaching from its surface, which in turn generate recoil force to thrust nanoswimmers propelling forward. Herein, bubble propulsion mechanism originating from momentum change of a Au-Ni-Pt nanoswimmer-O₂ bubble integral system is proposed to investigate the propulsion of nanoswimmers. Experiments are mainly focused on characterizing the propulsion of nanoswimmers in diluted H₂O₂ by changing the temperature of the solution. Results show that Au-Ni-Pt nanoswimmers are able to propel forward while the generated O₂ bubbles are detached from the Pt-surface. The speeds of nanoswimmers are increased with the increment of temperature varying from 7 °C to 57 °C. It is concluded that the propulsion of nanoswimmers is temperature-dependent.

Mycobacterium tuberculosis is an infectious agent that causes tuberculosis (TB). TB is one of the major causes of death worldwide, mainly in the developing country. Early and rapid diagnosis of TB will be of great help to isolate the patients and control the disease. The aim of this research is to detect Mycobacterium tuberculosis using voltammetric DNA biosensor by using gold electrode modified by self assembled monolayer with thiol. Single-stranded probe DNA was immobilized on the surface of self assembled monolayer gold electrode with the assistance of cysteamine and glutaraldehyde, which was further used to hybridize with the target DNA sequence and non-complementary target sequence. Differential Pulse Voltammetry (DPV) was used to study the immobilization of DNA probe and hybridization with the target DNA. The hybridization reaction on the gold electrode surface was detected by monitoring a guanine oxidation signal at +0.2 Volt. Voltammetric DNA biosensor using gold electrode modified with thiol can be used to determine hybridization between probe DNA and target DNA sequence of M. tuberculosis with sensitivity value is 0.5175 for target DNA in concentration range 0- 30 μg/mL; detection limit is 2.7046 μg/mL and quantification limit is 9.0155 μg/mL, accuracy is 99.22%, precision 99.86%

Foodborne diseases is a major public health concern and costs billions of dollars losses every year. For example, 93.8 million cases of gastroenteritis reported in Europe, United States, South America and Asia. Different methods depending on various scientific principles are used for detection of pathogenic bacteria relating foodborne diseases, conventional methods including culture-depending methods, microscopic, PCR, serological and biochemical methods are still used but majority of this methods suffers from a number of disadvantages includes long time-analysis, high cost, limited sensitivity and lab-based. Therefore, there is an urgent need for development of rapid screening assays for field applications with high sensitivity. In this study, we developed colorimetric immuno-sensor was developed and evaluated as a novel rapid detection nanosensing platform for the detection of foodborne pathogens such as Salmonella Typhimurium, Salmonella Enteritidis, Staphylococcus Aureus and Campylobacter Jejuni. The sensing platform composed of cotton swab and nanoparticles. Cotton swaps were functionalized with general or specific recognition receptors for collecting and pre-concentration of bacteria from the surfaces. Then the cotton swab was dipped in a developing solution to indicate the presence of specific bacteria. The developing solution has a cocktail of different coloured nanospheres conjugated with different recognition receptors for the various bacteria analytes was used to generate the different colours. The nanosensor was used for testing the bacteria on different surfaces mimicking the poultry processing units such as glass slides, stainless steel and chicken meat.

Acoustic wave devices are theoretically investigated in their potential role of technological platform for the development of sensors for liquid environments. In this study, we theoretically studied the propagation of in-plane polarized Lamb modes, Love modes, Shear Horizontal Plate modes along layered structures, aimed at the design of acoustic waveguides suitable to trade-off mass sensitivity and low loss. The phase velocity shift and attenuation due to the presence of a viscous liquid contacting the device surface and to a mass anchored to the sensor surface are calculated for different waveguide structures, confirming that the sensor behavior can be enhanced by a proper choice of the material parameters (i.e., material types, crystallographic orientation, electrical boundary conditions, and thicknesses) of the layered waveguide structure.

An influence of titanium oxide (TiO_x) deposition method, i.e., chemical (atomic layer deposition, ALD) and physical (reactive magnetron sputtering, RMS) vapor deposition, on the optical properties and surface chemical modification were investigated. TheTiO_x film was used as a functional coating for enhancing sensing properties of two types of label-free optical sensors, i.e., localized surface plasmon resonance (LSPR) sensors based on gold nanoparticles and induced in optical fibre long-period gratings (LPGs) working in visible and infrared spectral range, respectively. We have found that independently on deposition method the films increase the sensitivity of LPG and enhance biofunctionalization capabilities.

In biological fluids, proteins and other biomolecules bind to the surface of nanoparticles to form a coating known as the protein corona which in turn becomes primary determinant of the nanoparticles’ fate and behaviour. Here we develop a QCM-based platform and methodology to obtain data from real-time interactions of nanoparticles with selected human plasma proteins. Polystyrene particles coated with transferrin are immobilized on QCM sensor chips and by means of a ‘sandwich’ format binding assay, specific epitopes on the particles can be quantified as measured by the increase of the sensor's resonant frequency. Cell binding experiments where adherent cells are directly grown on the sensor surface are also performed. Interaction of nanoparticles injected over the cell surface is observed only in the case of particle-transferrin complexes demonstrating that it is the nanoparticle-corona complex, rather than the native nanoparticle, “what the cell sees”, with the corona being the interface between the nanoparticle and the cellular system. Our data highlight the potential of the proposed QCM-based platform and methodology for characterization of the bio-nano-interface and tracking the interaction of nanoparticles with biological cells in the presence of a realistic milieu.