Dynamic information of signaling processes inside living cells is important to a fundamental biological understanding of cellular processes. Many traditional microscopy techniques involve incubation of cells with fluorescent dyes or nanoparticles, and examining the interaction of these dyes with compounds of interest. However, when a dye or nano-particle is incubated into a cell, it is transported to certain intracellular sites that may or may not be where it is most likely to stay, and not to areas where the investigator would like to monitor. The fluorescence signals which are supposed to reflect the interaction of the dyes with chemicals of interest is generally directly related to the dye concentration as opposed to the analyte concentration. Only with optical nanosensors can excitation light be delivered to specific locations inside cells. An important feature of nanosensors is the minimal invasiveness of the monitoring process. A cell survival study was previously performed whereby an investigation was made to determine whether penetration of the cell by the nanosensor resulted in intracellular or membrane damage of such a nature as to compromise cellular viability. It was determined that the process of mitosis continued normally, and that nanosensor insertion and withdrawal did not affect the life cycle of the cell. Nanosensors are an important technology that can be used to measure biotargets in a living cell, and that does not significantly affect cell viability. Combined with the exquisite molecular recognition of antibody probes, nanosensors could serve as powerful tools capable of exploring biomolecular processes in subcompartments of living cells. They have a great potential to provide the necessary tools to investigate multiprotein molecular machines of complex living systems, and the complex network that controls the assembly and operation of these machines in a living cell. Future developments would lead to the development of nanosensors equipped with nanotool sets that enable tracking, assembly, and disassembly of multiprotein molecular machines and their individual components. These nanosensors would have multifunctional probes (antibody as well as DNA probes) that could measure the structure of biological components in single cells. Until now, scientists have been limited to investigating the workings of individual genes and proteins by breaking the cell apart and studying its individual components in vitro. The advent of nanosensors will hopefully permit research on entire networks of genes and proteins in an entire living cell in vivo.

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