Development of Silsesquioxane-based Molecular Materials Modified with Luminescent Transition Metal Complexes as a New Nanoplatform for Bioimaging and Therapeutic Applications

Project: Research

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The aim of this project is the exploitation of polyhedral oligomeric silsesquioxane (POSS) modified with luminescent transition metal complexes as a nanoplatform for a range of functional moieties for the development of new cellular reagents. POSS are the smallest silica nanoparticles with a well-defined molecular structure. Among these molecules, the most investigated one is octasilsesquioxane because it is highly symmetrical and can be easily modified with different corner functional groups. In addition to the advantages exhibited by common dendrimers such as multiple functionalities and three-dimensional macromolecular scaffolds, the POSS core also possesses other characteristics such as high thermal stability, rigidity, and hydrophobicity. These interesting properties allow them to be utilized as unique and innovative building blocks for new hybrid nanocomposites, supramolecular assemblies, and functional materials. In terms of biological applications, fluorescent POSS molecules have been employed as bioimaging probes, modifiers for nanoparticles, delivery systems for biomolecules, and photodynamic therapy agents. Despite these advances, the work reported thus far has focused on the use of fluorescent organic dyes. Recently, the remarkable emission properties and biological activity of luminescent transition metal complexes have inspired the design of bioimaging reagents and anticancer drugs. However, the applications have been severely limited by the low water solubility and high cytotoxicity of metal complexes. Thus, there is an urgent need to search for a molecular platform that will confer excellent biocompatibility on luminescent transition metal complexes, retain their favorable photophysical and photochemical properties, and preferably provide additional functionalization opportunities. In view of its small size, rigid core, hydrophobic surface, high functional group density, optically transparent and nonfluorescent character, and noncytotoxic nature, we believe that POSS is a promising candidate to be exploited as a nanoplatform for the construction of luminescent transition metal complex-based biological reagents. This interesting nanosized unit will endow luminescent transition metal complexes with new chemical and biological properties, and further enhance their versatility and applicability in cellular studies. In this project, we will design new luminescent POSS-transition metal complex conjugates modified with different functional pendants with bioorthogonal labeling, organelle-selective, and cancer cell-targeting capabilities. The photophysical and photochemical properties of the conjugates will be examined. Additionally, the cytotoxicity, cellular uptake, and intracellular localization properties of the conjugates will be investigated. We are confident that the integration of the favorable characteristics of POSS and luminescent transition metal complexes will lead to the development of innovative reagents for a range of bioimaging and therapeutic applications.


Project number9042679
Grant typeGRF
Effective start/end date1/09/18 → …