Pankaj Pathak

Metal-coated nanoscale TiO2 catalysts for enhanced CO2 photoreduction

Nanoscale TiO2 particles embedded in the hydrophilic cavities of Nafion membrane films were coated with silver for significantly improved photoconversion of CO2. The primary product from the photocatalytic reduction became methanol, with the overall conversion efficiency higher than that without the silver coating. These catalytic films are also stable chemically and photochemically, reusable in repeated reactions. The results from the characterization of the nanoparticles and the use of films with different silver loadings are presented and discussed.

Improving photoreduction of CO2 with homogeneously dispersed nanoscale TiO2 catalysts

Significantly improved photoconversion of CO2 was achieved with photocatalysts of nanoscale TiO2 particles homogeneously dispersed in porous cavities of optically transparent ionomer membrane thin films.

Supercritical fluid technology for enhanced drug delivery

The rapid advances in the development of formulation and delivery systems based on micron-sized and nanoscale drug particles will create significant benefits to the pharmaceutical industry. Complementary to traditional methods, supercritical fluid techniques have found many useful, and sometimes unique, applications in the production and processing of drug particles. In this article background information is provided on a variety of supercritical fluid techniques relevant to drug formulation and delivery, recent advances and novel applications are highlighted, and the successful development of a new supercritical fluid rapid expansion technique for producing exclusively nanoscale drug particles will be discussed. Challenges and opportunities for further development and future applications are also reviewed.

Supercritical Fluid Technology for Nanotechnology in Drug Delivery

In the past few decades, supercritical fluid technology has attracted the attention of both scientists and engineers (McHugh and Krukonis, 1994; Taylor, 1996; Brennecke, 1993; Hutchenson and Foster, 1995; Levelt Sengers, 1991; Kendall et al., 1999). Early studies on the application of supercritical fluid technology were primarily in extraction and chromatography. Extensive experimental and theoretical investigations have been aimed toward an understanding of the properties of supercritical fluid systems, particularly intermolecular interactions (solute–solvent, solvent– solvent, and solute–solute) in supercritical fluid solutions (Tucker, 1999; Jessop and Leitner, 1999; Sun, 2002).Much progress has also beenmade in the use of supercritical fluids and mixtures as reaction media for chemical synthesis and as alternative solvent systems for materials processing (Sun, 2002; Poliakoff et al., 1996; Kajimoto, 1999; Savage, 1999; Musie et al., 2001). Recently, several supercritical fluid processing techniques have found significant applications in the nanotechnology development for drug formulation and delivery, especially the production of nanosized drugs and pharmaceuticals. In fact, drug formulation and delivery-related applications have emerged as a new frontier in the development of supercritical fluid technology. In this chapter, we provide background information on the supercritical fluid processing techniques relevant to drug formulation and delivery, highlight the recent advances and novel applications, and discuss the successful development of a new supercritical fluid rapid expansion technique for producing exclusively nanoscale drug particles.