Atul Tiwari

Template-Directed Hierarchical Self-Assembly of Graphene Based Hybrid Structure for Electrochemical Biosensing

A template-directed self-assembly approach, using functionalised graphene as a fundamental building block to obtain a hierarchically ordered graphene-enzyme-nanoparticle bioelectrode for electrochemical biosensing, is reported. An anionic surfactant was used to prepare a responsive, functional interface and direct the assembly on the surface of the graphene template. The surfactant molecules altered the electrostatic charges of graphene, thereby providing a convenient template-directed assembly approach to a free-standing planar sheet of sp(2) carbons. Cholesterol oxidase and cholesterol esterase were assembled on the surface of graphene by intermolecular attractive forces while gold nanoparticles are incorporated into the hetero-assembly to enhance the electro-bio-catalytic activity. Hydrogen peroxide and cholesterol were used as two representative analytes to demonstrate the electrochemical sensing performance of the graphene-based hybrid structure. The bioelectrode exhibited a linear response to H2O2 from 0.01 to 14 mM, with a detection limit of 25 nM (S/N=3). The amperometric response with cholesterol had a linear range from 0.05 to 0.35 mM, sensitivity of 3.14 µA/µM/cm(2) and a detection limit of 0.05 µM. The apparent Michaelis-Menten constant (Km(app)) was calculated to be 1.22 mM. This promising approach provides a novel methodology for template-directed bio-self-assembly over planar sp(2) carbons of a graphene sheet and furnishes the basis for fabrication of ultra-sensitive and efficient electrochemical biosensors.

Sol-Gel Route for the Development of Smart Green Conversion Coatings for Corrosion Protection of Metal Alloys

The development of coatings through sustainable routes is needed for the modern industrial sector. The process parameters and chemical ingredients should be wisely chosen to meet the demand of environmental friendly synthetic technologies. In this chapter, the authors have demonstrated the adaptability of using the sol-gel route for the development of eco-friendly (green) silicone coating compositions containing titanium nanoparticles. The developed coating composition was characterized with Fourier Transform Infrared (FTIR), Raman, Nuclear Magnetic Resonance (NMR), and X-ray Photoelectron spectroscopies. The thermal stability of the material was determined using thermogravimetric analysis (TGA). The surface morphology of the coatings was studied with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The corrosion resistance and impervious barrier properties of the Green Conversion Coating (GCC) were evaluated by a series of laboratory and outdoor corrosive atmosphere exposure experiments.

Nanoindentation, Nanoscratch and Dynamic Mechanical Analysis of High Performance Silicones

This chapter describes the basic fundamental principles that are required to understand the operation of modern nanoindentation techniques. Special attention has been paid to explain the terms that an experimentalist should know while analyzing the data from nanoindentation. Studies conducted by different researcher using nanoindentation techniques have been briefly mentioned as examples. Additionally, studies conducted on silicone quasi-ceramic coatings are also provided.

Antimicrobial Coatings—Technology Advancement or Scientific Myth

The demand of new antimicrobial products is increasing due to the increase in spread of infections and reduction in the effectiveness of the existing industrial products. It is, however, extremely difficult to develop a universal product that could regulate or stop the entire infectious occurrence. Companies are claiming to produce or develop new products that would help in limiting the spreading of infectious microbes. An enormous amount of work has been conducted in both the academic and industrial sectors on understanding the origin and possible regulations of the health hazards through microbes. This chapter discusses the volume of work that has been accomplished so far in the area of antimicrobial products development. An attempt has been made to summarize the utility of various marketed commercially available products along with their associated in-depth chemistry. Due to the proprietary nature of the information out of the commercial products, a limited technical investigation was accomplished.

Polymer-Based Antimicrobial Coatings as Potential Biomaterials: From Action to Application

An important task to provide an overview of the current developments in antimicrobial surface coatings for use in the biomedical field and of the clinical microbiology laboratory is the performance of antimicrobial susceptibility testing of significant bacterial isolates. The goals of testing are to detect possible materials that show resistance in common pathogens and to assure susceptibility to drugs of choice for particular infections. The most widely applied testing methods include broth microdilution or rapid automated instrument methods that use commercially marketed materials and devices. Manual methods that provide flexibility and possible cost savings include the disk diffusion and gradient diffusion methods. Each method has strengths and weaknesses, including organisms that may be accurately tested by the method. Some methods provide quantitative results, and all provide qualitative assessments using the categories susceptible, intermediate, or resistant. In general, current testing methods provide accurate detection of common antimicrobial resistance mechanisms, for example, thin-layer chromatography, agar diffusion, direct bioautography, time-kill test, ATP bioluminescence assay, and flow cytofluorometric method.