비만아 부모의 돌봄 경험: q 방법론

Recent biomedical applications of gold nanoparticles: A review.

The field of nanotechnology mainly encompasses with biology, physics, chemistry and material sciences and it develops novel therapeutic nanosized materials for biomedical and pharmaceutical applications. The biological syntheses of nanoparticles are being carried out by different macro-microscopic organisms such as plant, bacteria, fungi, seaweeds and microalgae. The biosynthesized nanomaterials have been effectively controlling the various endemic diseases with less adverse effect. Plant contains abundant natural compounds such as alkaloids, flavonoids, saponins, steroids, tannins and other nutritional compounds. These natural products are derived from various parts of plant such as leaves, stems, roots shoots, flowers, barks, and seeds. Recently, many studies have proved that the plant extracts act as a potential precursor for the synthesis of nanomaterial in non-hazardous ways. Since the plant extract contains various secondary metabolites, it acts as reducing and stabilizing agents for the bioreduction reaction to synthesized novel metallic nanoparticles. The non-biological methods (chemical and physical) are used in the synthesis of nanoparticles, which has a serious hazardous and high toxicity for living organisms. In addition, the biological synthesis of metallic nanoparticles is inexpensive, single step and eco-friendly methods. The plants are used successfully in the synthesis of various greener nanoparticles such as cobalt, copper, silver, gold, palladium, platinum, zinc oxide and magnetite. Also, the plant mediated nanoparticles are potential remedy for various diseases such as malaria, cancer, HIV, hepatitis and other acute diseases.

Biosynthesis of metallic nanoparticles using plant derivatives and their new avenues in pharmacological applications – An updated report

Electrochemical sensor and biosensor platforms based on advanced nanomaterials for biological and biomedical applications.

Development of reliable and eco-accommodating methods for the synthesis of nanoparticles is a vital step in the field of nanotechnology. Silver nanoparticles are important because of their exceptional chemical, physical, and biological properties, and hence applications. In the last decade, numerous efforts were made to develop green methods of synthesis to avoid the hazardous byproducts. This review describes the methods of green synthesis for Ag-NPs and their numerous applications. It also describes the comparison of efficient synthesis methods via green routes over physical and chemical methods, which provide strong evidence for the selection of suitable method for the synthesis of Ag-NPs.

A review on green synthesis of silver nanoparticles and their applications

We report results of studies relating to the development of an electrochemical immunosensor based on carboxylated multiwalled carbon nanotubes (c-MWCNTs) electrophoretically deposited onto indium tin oxide (ITO) glass. This c-MWCNTs/ITO electrode surface has been functionalized with monoclonal aflatoxin B1 antibodies (anti-AFB1) for the detection of aflatoxin-B1 using electrochemical technique. Electron microscopy, X-ray diffraction and Raman studies suggest successful synthesis of c-MWCNTs and the Fourier transform infra-red spectroscopic (FT-IR) studies reveal its carboxylic functionalized nature. The proposed immunosensor shows high sensitivity (95.2 μA ng−1 mL cm−2), improved detection limit (0.08 ng mL−1) in the linear detection range of 0.25–1.375 ng mL−1. The low value of association constant (0.0915 ng mL−1) indicates high affinity of immunoelectrode towards aflatoxin (AFB1).

Carboxylated multiwalled carbon nanotubes based biosensor for aflatoxin detection

We report here the biosynthesis of gold and silver nanoparticles using leaf extract of ginger (Zingiber officinale). The treatment of aqueous solution of AgNO3 and HAuCl4 with ginger leaf extract resulted in rapid formation of stable nanoparticles for both metals. The growth of nanoparticles is monitored by UV-vis spectrophotometer and complemented with characterization using Transmission Electron Microscopy, X-ray Diffraction and Fourier Transform Infrared Spectroscopy. Plausible mechanism for the formation of nanoscale and dfference in reduction time for gold and silver nanoparticle synthesis is discussed on the basis of pH. Transmission Electron Microscopy revealed the presence of polydisperse gold and silver nanoparticles with an average size of 10nm and 30.31nm respectively. X-ray diffraction studies corroborated that the biosynthesized nanoparticles are crystalline gold and silver. Furthermore, this green biogenic approach is rapid and simple alternative to chemical synthesis.

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A green biogenic approach for synthesis of gold and silver nanoparticles using zingiber officinale

We report the fabrication of an efficient, label-free, selective and highly reproducible immunosensor with unprecedented sensitivity (femto-molar) to detect a breast cancer biomarker for early diagnostics. Mesoporous zinc oxide nanofibers (ZnOnFs) are synthesized by electrospinning technique with a fiber diameter in the range of 50–150 nm. Fragments of ZnOnFs are electrophoretically deposited on an indium tin oxide glass substrate and conjugated via covalent or electrostatic interactions with a biomarker (anti-ErbB2; epidermal growth factor receptor 2). Oxygen plasma treatment of the carbon doped ZnOnFs generates functional groups (–COOH, –OH, etc.) that are effective for the conjugation of anti-ErbB2. ZnOnFs without plasma treatment that conjugate via electrostatic interactions were also tested for comparison. Label-free detection of the breast cancer biomarker by this point-of-care device is achieved by an electrochemical impedance technique that has high sensitivity (7.76 kΩ μM−1) and can detect 1 fM (4.34 × 10−5 ng mL−1) concentration. The excellent impedimetric response of this immunosensor provides a fast detection (128 s) in a wide detection test range (1.0 fM–0.5 μM). The oxy-plasma treated ZnOnF immunoelectrode shows a higher association constant (404.8 kM−1 s−1) indicating a higher affinity towards the ErbB2 antigen compared to the untreated ZnOnF immunoelectrode (165.6 kM−1 s−1). This sensor is about an order of magnitude more sensitive than the best demonstrated in the literature based on different nanomaterials and about three orders of magnitude better than the ELISA standard for breast cancer biomarker detection. This proposed point-of-care cancer diagnostic offers several advantages, such as higher stability, rapid monitoring, simplicity, cost-effectiveness, etc., and should prove to be useful for the detection of other bio- and cancer markers.

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Anti-epidermal growth factor receptor conjugated mesoporous zinc oxide nanofibers for breast cancer diagnostics

This report presents a rapid, reproducible and a green biogenic approach for the biosynthesis of gold and silver nanoparticles using leaf extract of Dalbergia sissoo. The biomolecules present in the plant induced the reduction of Au 3+ and Ag + ions from HAuCl4 and AgNO3 respectively, which resulted in the formation of Dalbergia conjugated nanoparticles. The growth of nanoparticles was monitored by UV-vis spectrophotometer that demonstrated a peak at 545 and 425 nm corresponding to Plasmon absorbance of gold and silver nanoparticles respectively. The leaf extract was found to direct different shape and sized gold nanoparticles. Gold nanoparticles were 50-80 nm in size and their shape varied from spherical to few triangular and hexagonal polyshaped. While silver nanoparticle synthesized were spherical, in the range of 5-55 nm in size. X-ray diffraction studies corroborated that the biosynthesized nanoparticles were crystalline gold and silver. Fourier transform infra- red spectroscopy analysis revealed that biomolecules were involved in the synthesis and capping of silver nanoparticles and gold nanoparticles. Copyright © 2012 VBRI press.

Biocompatible synthesis of silver and gold nanoparticles using leaf extract of Dalbergia sissoo

There is an increased interest toward the development of bioelectronic devices for food toxin (mycotoxins) detection. Mycotoxins are highly toxic secondary metabolites produced by fungi like Fusarium, Aspergillus, and Penicillium that are frequently found in crops or during storage of food including cereals, nuts, fruits, etc. The contamination of food by mycotoxins has become a matter of increasing concern. High levels of mycotoxins in the diet can cause adverse, acute, and chronic effects on human health and a variety of animal species. Side effects may particularly affect the liver, kidney, nervous system, endocrine system, and immune system. Among 300 mycotoxins known till date, there are a few that are considered to play an important part in food safety, and for these, a range of analytical methods have been developed. Some of the important mycotoxins include aflatoxins, ochratoxins, fumonisins, citreoviridin, patulin, citrinin, and zearalenon. The conventional methods of analysis of mycotoxins normally require sophisticated instrumentation, e.g., liquid chromatography with fluorescence or mass detectors, combined with extraction procedures for sample preparation. Hence, new analysis tools are necessary to attain more sensitive, specific, rapid, and reliable information about the desired toxin. For the last about two decades, the research and development of simpler and faster analytical procedures based on affinity biosensors has aroused much interest due to their simplicity and sensitivity. The nanomaterials have recently had a great impact on the development of biosensors. The functionalized nanomaterials are used as catalytic tools, immobilization platforms, or as optical or electroactive labels to improve the biosensing performance to obtain higher sensitivity, stability, and selectivity. Nanomaterials, such as carbon nanomaterials (carbon nanotubes and graphene), metal nanoparticles, nanowires, nanocomposites, and nanostructured metal oxide nanoparticles are playing an increasing role in the design of sensing and biosensing systems for mycotoxin determination. Furthermore, these nanobiosystems are also bringing advantages in terms of the design of novel food toxin detection strategies. We will focus on some of the recent results related to fabrication of nanomaterial-based biosensors for food toxin detection obtained in our laboratories.

Chandan Singh

Papers

Carboxylated multiwalled carbon nanotubes based biosensor for aflatoxin detection

A green biogenic approach for synthesis of gold and silver nanoparticles using zingiber officinale

Anti-epidermal growth factor receptor conjugated mesoporous zinc oxide nanofibers for breast cancer diagnostics

Biocompatible synthesis of silver and gold nanoparticles using leaf extract of Dalbergia sissoo

Nanomaterial-Based Biosensors for Food Toxin Detection