Study of Self-Assembly of Nanoporous Silica Particles and Biomolecules on Sensing Surfaces

The presented research is related to a general topic of Self-Assembly in Soft Condensed Matter Physics. Specifically, the research described here deal with (a) self-assembly of complex-shaped nanoporous (called also mesoporous in chemical sciences) colloidal silica particles, fundamentals of their synthesis and the applications in nanophotonics (synthesis of ultrabright nanoporous silica particles), and (b) investigation of self-assembly of biomolecules on sensing surfaces that are used in biosensors.;Nanoporous silica particles represent an example of self-assembly of shapes that have complexity comparable to existing so far only in the biological world. Understanding of the mechanism of shape formation of such particles is important from both fundamental and applied points of view. If we want to synthesize particles with predictable and reproducible shapes, we have to understand the shape formation mechanisms. Here we describe our advances in understanding of these mechanisms. In particular, we will show that the final shaping of these particles can be described as a thermodynamical equilibrium process, which is a quite unexpected result. Synthesis of ultrabright fluorescent mesoporous silica particles exemplifies the studied mechanism of self-assembly. This application demonstrates ability to create a unique nano environment for optically active dyes; both can emerge into a translational research towards creation of fluorescent tags and labels, and a new type of sensors. This application can be of paramount importance in biomedical labeling, tracing, tagging. It can also be used in material science. A particular emphasis will be given to the synthesis of ultrabright fluorescent silica nanoparticles. The knowledge of self-assembly mechanism helps us to design nanoparticles while keeping the ultrabrightness.;In the last part of this thesis, we study the assembly of biomolecules in the sensing layer of biosensors, in particular, immunosensors. Immunosensors are a broad class of biosensors based on antigen-antibody specific affinity, which allow for highly accurate, specific, and sensitive diagnostics. However, there is a need in higher sensitivity and faster immunodetection. While the majority of immunosensors study is related to biochemistry, self-assembly of molecules on the sensing surfaces has not been virtually investigated. We demonstrate how it can be done with the help of atomic force microscopy (AFM). Our study of the sensing layers is done with the help of AFM. We developed an AFM method for characterization of the molecular density and thickness of the molecular layer assembled on the sensing surface. In particular, this allowed us to discover that the modern popular enzyme-linked immunoassay (ELISA) could be scaled down more than 4 million times without sacrificing their detection ability.;Future work will be focused on developing ultrabright nanoporous silica nanoparticles modified with amino groups for purpose of application for biology and medicine. Synthesis of microthermometers based on non-radiative energy transfer (FRET) between two fluorescent dye molecules will be attempted too.