Research Projects

Nano-hybrids composed of metal nanoparticles (inorganic part) and photoactive dyes (organic part) are very promising for molecular sensing, photo-energy conversion, and photo-catalysis applications. The field of hybrid materials interfacing with organic molecules such as dyes is less developed, except in some specific cases, such as metal-semiconductor nanoparticles. These nano-hybrids exploit the key optical features of noble-metal nanoparticles, which exhibit strong localized surface plasmon resonances (LSPR), and their modifications by interaction with the organic compounds. Photophysical properties of these hybrids depend on several nano-hybrid design variables (often correlated), including the metal-to-dye distance, the molecular dipole orientation versus the metallic surface, the nanoparticle size and shape, and the spectral overlap of the dye with the surface plasmon band of the nanoparticle. We proposed the development of novel nano-hybrids based on nanobipyramids (NBPs) and phtalocyanine (PC) dye. NBPs show large electric field enhancements at their sharp tips than nanorods which can be used for emission enhancement and they exhibit two plasmon resonance bands localized at 520 nm and 850 nm. Interestingly, plasmon extinction band of NBPs also is in the range of absorption and emission band of PC dye which is essential for optimal photo-physical properties of nano-hybrids. To the best of our knowledge, hitherto, there has been no report on the detailed molecular dynamics study to investigate different interfaces of such gold nanobipyramids-dye based nano-hybrids. Controlling nano-hybrid design variables for optimum photo-physical properties of gold nanobipyramids-dye based nano-hybrids during the synthesis and surface modification is a challenging task. Therefore, a detailed theoretical investigation of different interfaces of such nano-hybrids which complements the experimental scenario is urgently required to design these nano-objects for optimal photo-physical properties. We have already developed molecular dynamics simulation models for nanobipyramids and their interfaces. Using these models, we have investigated the origin of controlled anisotropic growth in monodisperse gold nanobipyramids. The results of this study have been published in Nanoscale [SK Meena, Nanoscale, 2021, 13, 15292-15300]. Furthermore, in this project, we aim to develop molecular dynamics simulation models for various interfaces of nanobipyramids, focusing on ligand exchange of CTAB surfactants with Tween80 and subsequent functionalization with dye molecules. Such models will be validated with structural characterization and dynamic properties obtained experimentally. We believe that our research outcome would certainly boost further development in synthesis protocols of gold nanobipyramids and dye based nano-hybrids for optimal photo-physical properties for applications involving molecular sensing, photo-energy conversion, and photo-catalysis.