Live Cell Microscopy: A Physical Chemistry Approach

Abstract

Probing dynamics of intracellular components using physical chemistry techniques is a remarkable bottom-up approach for understanding the structures and functions of a biological cell. In this "Feature Article", we give an overview on local polarity, solvation, viscosity, acid-base property, red-ox processes (thiol-disulfide exchange), and gene silencing at selected intracellular components inside a live cell. Significant differences have been observed between cancer cells and their noncancer counterparts. We demonstrate that thiol-disulfide exchange, calcium oscillation, and gene silencing are manifested in time dependence of fluorescence intensity. We show that fluorescent gold nanoclusters may be used in drug delivery (e.g., doxorubicin) and selective killing of cancer cells. Further, we discuss dynamics and structural changes of DNA quadruplexes and i-motifs, induced by different external conditions (e.g., pH) and additives (e.g., K and other target specific small molecules). We demonstrate that peptidomimetic analogues have high specificity over double-stranded DNA for binding with i-motifs and G-quadruplexes. These results may have significant biological implications.

Time Evolution of Local pH Around a Photo‐Acid in Water and a Polymer Hydrogel: Time Resolved Fluorescence Spectroscopy of Pyranine

“…Acid‐base reaction is one of the fundamental chemical reactions in nature and has implications in many natural and biological processes . The dissociation equilibrium of an acid HA into proton and its deprotonated species (A − ) is, …”

“…The primary prcocesses of excited state proton transfer (ESPT) of HPTS in a wide variety of media have been monitored by time evolution of the fluorescence from the anion (A − *) and the undissociated acid (HA*). This includes binary solvent mixtures, live biological cell, reverse micelles, micelle, nafione membrane and niosome .…”

“…[8][9][10][11][12] ESPT is implicated in rhodopsin (involved in the vison process) [13] and in green fluorescence protein (GFP). [14][15] The primary prcocesses of excited state proton transfer (ESPT) of HPTS in a wide variety of media [10][11][12][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] have been monitored by time evolution of the fluorescence from the anion (A À *) and the undissociated acid (HA*). This includes binary solvent mixtures, [10][11]22] live biological cell, [17,18] reverse micelles, [19,30,32] micelle, [21] nafione membrane [30] and niosome.…”

Probing Deviation of Adhered Membrane Dynamics between Reconstituted Liposome and Cellular System

“…Therefore, it is extremely important to understand the structural dynamics of cell‐cell adhesion. Structural fluctuation is crucial in enzymes, microtubule dynamics, antigen‐antibody complex, and different organelles of a live cell . As an adhered system comprises of at least two different cell membranes, independent labeling of each cell membrane requires a suitable pair of dyes.…”

“…Structural fluctuation is crucial in enzymes, [6][7][8][9][10][11][12] microtubule dynamics, [13] antigen-antibody complex, [14] and different organelles of al ive cell. [15][16][17] As an adhered system comprises of at least two different cell membranes, independent labeling of each cell membrane requires as uitable pair of dyes. This enables us to understand the dynamics of individual component of an adhered system.However,t his is ac hallenging task for live cell.…”