This review covers general information about the eco-friendly process for the synthesis of silver nanoparticles (AgNP) and gold nanoparticles (AuNP) and focuses on mechanism of the antibacterial activity of AgNPs and the anticancer activity of AuNPs. Biomolecules in the plant extract are involved in reduction of metal ions to nanoparticle in a one-step and eco-friendly synthesis process. Natural plant extracts contain wide range of metabolites including carbohydrates, alkaloids, terpenoids, phenolic compounds, and enzymes. A variety of plant species and plant parts have been successfully extracted and utilized for AgNP and AuNP syntheses. Green-synthesized nanoparticles eliminate the need for a stabilizing and capping agent and show shape and size-dependent biological activities. Here, we describe some of the plant extracts involved in nanoparticle synthesis, characterization methods, and biological applications. Nanoparticles are important in the field of pharmaceuticals for their strong antibacterial and anticancer activity. Considering the importance and uniqueness of this concept, the synthesis, characterization, and application of AgNPs and AuNPs are discussed in this review.

Eco-friendly approach for nanoparticles synthesis and mechanism behind antibacterial activity of silver and anticancer activity of gold nanoparticles

Emerging nanotechnology-based strategies for the identification of microbial pathogenesis

Cholera continues to represent a major threat to human health, particularly in developing countries. Death can be readily avoided when medical treatment is rapidly administered. In order to provide a means of detecting the bacterially secreted toxin, we have developed a simple, yet rapid, bioassay for the cholera toxin. The colorimetric bioassay is based on a specifically synthesized lactose derivative that is self-assembled onto gold nanoparticles of 16 nm diameter. In solution the lactose-stabilized nanoparticles are red in color due to the intense surface plasmon absorption band centered at 524 nm. Cholera toxin (added as the B-subunit) (CTB) binds to the lactose derivative and induces aggregation of the nanoparticles. Upon aggregation, the surface plasmon absorption band broadens and red shifts such that the nanoparticle solution appears a deep purple color. The selectivity of the bioassay stems from the thiolated lactose derivative that mimics the GM1 gangliosidethe receptor to which cholera toxin bi...

Glyconanoparticles for the colorimetric detection of cholera toxin

Excellent triboelectric and mechanical properties are achieved on the same material for the first time by developing an effective, general, straightforward, and area-scalable approach to surface modification of a polyethylene terephthalate (PET) film via inductive-coupled plasma etching. The modification enables gigantic enhancement of triboelectric charge density on the PET surface. Based on the modified PET as a contact material, a triboelectric nanogenerator (TENG) exhibits significantly promoted electric output compared to the one without the modification. The obtained electric output is even superior to a TENG made of conventional polytetrafluoroethylene that is known for its strongest ability of being charged by triboelectrification among all engineering plastics. Detailed characterizations reveal that the enhancement of triboelectric charge density on the PET is attributed to both chemical modification of fluorination and physical modification of roughened morphology in nanoscale. Therefore, this work proposes a new route to obtaining high-performance TENGs by manipulating and modifying surface properties of materials.

Significant Enhancement of Triboelectric Charge Density by Fluorinated Surface Modification in Nanoscale for Converting Mechanical Energy

Microarrays provide a powerful analytical tool for the simultaneous detection of multiple analytes in a single experiment. The specific affinity reaction of nucleic acids (hybridization) and antibodies towards antigens is the most common bioanalytical method for generating multiplexed quantitative results. Nucleic acid-based analysis is restricted to the detection of cells and viruses. Antibodies are more universal biomolecular receptors that selectively bind small molecules such as pesticides, small toxins, and pharmaceuticals and to biopolymers (e.g. toxins, allergens) and complex biological structures like bacterial cells and viruses. By producing an appropriate antibody, the corresponding antigenic analyte can be detected on a multiplexed immunoanalytical microarray. Food and water analysis along with clinical diagnostics constitute potential application fields for multiplexed analysis. Diverse fluorescence, chemiluminescence, electrochemical, and label-free microarray readout systems have been developed in the last decade. Some of them are constructed as flow-through microarrays by combination with a fluidic system. Microarrays have the potential to become widely accepted as a system for analytical applications, provided that robust and validated results on fully automated platforms are successfully generated. This review gives an overview of the current research on microarrays with the focus on automated systems and quantitative multiplexed applications.

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Automated analytical microarrays: a critical review.

Antibody microarrays for native toxin detection

Reactive ion etching (RIE) was used to pattern antibodies onto the surfaces of polymer substrates. A low pressure, inductively coupled oxygen plasma was used to anisotropically etch 25−30 μm deep features into poly(methyl methacrylate) (PMMA), Zeonex, and polycarbonate (PC). Scanning electron microscopy and contact angle measurements show that the resulting surfaces exhibit significant microroughness and enhanced hydrophilicity. Fourier transform infrared spectroscopy suggests that, in addition to enhanced surface area, chemical modifications may contribute to antibody immobilization. Polyclonal antibodies preferentially bind to the etched areas in RIE-patterned PMMA and Zeonex substrates but localize in unetched regions of RIE-patterned PC surfaces. Simple immunoassays were performed to demonstrate a potential application for RIE-modified polymer surfaces. Antibodies specific for the capture of fluorescently labeled cholera toxin, S. aureus enterotoxin B, and B. anthracis protective antigen were immobili...

Functional antibody immobilization on 3-dimensional polymeric surfaces generated by reactive ion etching

Disclosed herein are substrates comprising reactive ion etched surfaces and specific binding agents immobilized thereon. The substrates may be used in methods and devices for assaying or isolating analytes in a sample. Also disclosed are methods of making the reactive ion etched surfaces.

Victor C. Rucker

Papers

Antibody microarrays for native toxin detection

Functional antibody immobilization on 3-dimensional polymeric surfaces generated by reactive ion etching

Reactive ion etched substrates and methods of making and using