Herein we report biorecognition studies of protein IgG using biocomapatible gold nanorods as molecular probes. Surface modification of cetyltrimethylammonium bromide (CTAB)-stabilized gold nanorods was carried out by using poly(styrenesulfonate) (PSS) to reduce the toxicity of as-synthesized gold nanorods caused by free CTAB. ζ potential analysis confirmed charge reversal on the surface of gold nanorods caused by the PSS coating. Surface plasmon resonance exhibited by gold nanorods has been employed as a tool for analyzing the binding events for biomolecules. TEM results, showing the aggregation of gold nanorods, in addition to the shift in surface plasmon resonance peak in UV−vis absorption measurements, upon the interaction of biomolecules with gold nanorods, confirmed molecular binding. Morphological changes caused by the cellular uptake of gold nanorods before and after PSS modification have been observed. Cell viability studies using gold nanorods were performed to study the cytotoxic effects of these molecular probes.

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We report here the development of a seed-mediated growth method for the synthesis of iron oxide nanoparticles with tunable size distribution and magnetic properties. We have investigated the size distribution of seed as well as iron oxide nanoparticles during the growth process using transmission electron microscopy (TEM). It has been observed that the distribution of size gradually becomes narrow with time via the intraparticle ripening process and Oswald ripening process. The magnetization measurements were performed using a superconducting quantum interference device (SQUID) from room temperature to 5 K to determine the effect of size distribution on the blocking temperature (T b ) and splitting temperature (T splitting ). The thermogravimetric analyses exhibited the size-dependent weight loss of the magnetic nanoparticles. The in vitro cytotoxicity tests were also performed to determine the cell viability as a function of size and concentration of the magnetic nanoparticles.

The biosorption potential of three different agro-industrial waste materials of lignocellulosic origin, i. e., coir pith (CP), sawdust (SD) and sugarcane fiber (SF), is investigated in the case of basic dyes, i. e., crystal violet (CV) and rhodamine B (RB). The uptake of dyes from aqueous solutions is found to be rapid when using these candidate biosorbents. The application of various kinetic models reveals good correlation of a pseudo-second order kinetics model with the experimental data. Equilibrium adsorption data have been analyzed using nonlinearized forms of the Langmuir, Freundlich and Redlich-Peterson isotherms, to determine the best fit equation for the adsorption process. Experimental results show that all of the adsorbents are effective for the removal of dyes from aqueous solutions and their adsorption capacities are comparable with other reported adsorbents. Since the agricultural solid waste materials used in the present investigation are freely and abundantly available, the adsorption process is expected to be economically viable for wastewater treatment.

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