Jayanta Chakraborty

Synthesis of monodisperse copper nanoparticles using a modified digestive ripening technique and formation of superlattices

In this work we demonstrate for the first time the synthesis of monodisperse copper nanoparticles (5 ± 0.9 nm) and formation of 2-D and 3-D superlattices. Superlattices have been formed using slow destabilization of the colloid. A confined environment of the emulsion droplet has been used to promote formation of 3D superlattices. It has been shown that very compact crystal like superlattices can be formed if the destabilized sol is aged for 10 days at −4 °C.

A simple room temperature fast reduction technique for preparation of a copper nanosheet powder

In this study, we demonstrate the synthesis of stable large copper nanosheets using fast reduction at room temperature. Nanosheets are synthesized by reducing Cu(OH)42− with hydrazine hydrate in the presence of CTAB at room temperature. The size of the nanosheet is critically dependent on the concentration of NaOH and reducing agent, and an optimum concentration range has been determined experimentally. The large nanosheets may be centrifuged and dried into a powder and re-dispersed without any apparent size or shape change. Additional impurities (nano-rods, nano-particles) produced in the sub-optimal process is readily removed by the precipitation–re-dispersion process. While re-dispersing in chloroform, it was observed that the smaller nanosheets assembled like a pack of cards due to a high centrifugal field to form large nanosheets.

Synthesis and in situ observation of 3D superlattices of gold nanoparticles using oil-in-water emulsion.

In this work oil-in-water emulsion has been successfully used as a confined environment to grow 3D superlattices of gold nanoparticles. The superlattices were grown from 5 nm uniform gold nanoparticles using slow destabilization method. The confined environment was created by forming a stable emulsion where the gold colloid suspended in toluene was used as oil phase. Superlattices were also formed in bulk solution using the same slow destabilization method. A comparative study reveals that compact superlattices form more readily inside the emulsion drops as compared to bulk precipitation. The unstable colloid (in bulk or as emulsion) was aged for various periods at 5 °C to form more compact superlattices. The best superlattices with sharp corners are observed when the superlattices are formed inside the emulsion and aged for a month. Two key parameters, the incubation temperature and anti-solvent concentration, are optimized to obtain larger superlattices with sharp features. A new method is also demonstrated for in situ observation of superlattice formation using an optical microscope.

Interpreting nucleation as a network formation process

In this paper we interpret nucleation as a network formation process. Inspired by this interpretation we propose a social network model which produces networks with communities.

A structured review of baculovirus infection process: integration of mathematical models and biomolecular information on cell–virus interaction

The baculovirus expression vector system (BEVS) is an emerging tool for the production of recombinant proteins, vaccines and bio-pesticides. However, a system-level understanding of the complex infection process is important in realizing large-scale production at a lower cost. The entire baculovirus infection process is summarized as a combination of various modules and the existing mathematical models are discussed in light of these modules. This covers a systematic review of the present understanding of virus internalization, viral DNA replication, protein expression, budded virus (BV) and occlusion-derived virus (ODV) formation, few polyhedral (FP) and defective interfering particle (DIP) mutant formation, cell cycle modification and apoptosis during the viral infection process. The corresponding theoretical models are also included. Current knowledge regarding the molecular biology of the baculovirus/insect cell system is integrated with population balance and mass action kinetics models. Furthermore, the key steps for simulating cell and virus densities and their underlying features are discussed. This review may facilitate the further development and refinement of mathematical models, thereby providing the basis for enhanced control and optimization of bioreactor operation.