Investigating the Dynamics of Cellular Processes at the Single Molecule Level with Semiconductor Quantum Dots

2007 ◽  
pp. 427-441 ◽  
Author(s):  
Maxime Dahan
Keyword(s):  
Quantum Dots ◽  
Single Molecule ◽  
Semiconductor Quantum Dots ◽  
Single Molecule Level ◽  
Cellular Processes

scholarly journals Live-cell single-molecule labeling and analysis of myosin motors with quantum dots

2017 ◽  
Vol 28 (1) ◽  
pp. 173-181 ◽  
Author(s):  
Hiroyasu Hatakeyama ◽  
Yoshihito Nakahata ◽  
Hirokazu Yarimizu ◽  
Makoto Kanzaki
Keyword(s):  
Quantum Dots ◽  
Single Molecule ◽  
Intracellular Trafficking ◽  
Glucose Transporter ◽  
Insulin Treatment ◽  
Single Particle Tracking ◽  
Single Molecule Level ◽  
Cellular Processes ◽  
Myosin Motors ◽  
Glucose Transporter Glut4

Quantum dots (QDs) are a powerful tool for quantitatively analyzing dynamic cellular processes by single-particle tracking. However, tracking of intracellular molecules with QDs is limited by their inability to penetrate the plasma membrane and bind to specific molecules of interest. Although several techniques for overcoming these problems have been proposed, they are either complicated or inconvenient. To address this issue, in this study, we developed a simple, convenient, and nontoxic method for labeling intracellular molecules in cells using HaloTag technology and electroporation. We labeled intracellular myosin motors with this approach and tracked their movement within cells. By simultaneously imaging myosin movement and F-actin architecture, we observed that F-actin serves not only as a rail but also as a barrier for myosin movement. We analyzed the effect of insulin on the movement of several myosin motors, which have been suggested to regulate intracellular trafficking of the insulin-responsive glucose transporter GLUT4, but found no significant enhancement in myosin motor motility as a result of insulin treatment. Our approach expands the repertoire of proteins for which intracellular dynamics can be analyzed at the single-molecule level.

Nanomechanochemical Delivery of Nanoparticles for Nanomechanics Inside Living Cells

2010 ◽  
Author(s):  
Kyungsuk Yum ◽  
Sungsoo Na ◽  
Yang Xiang ◽  
Ning Wang ◽  
Min-Feng Yu
Keyword(s):  
Single Molecule ◽  
Living Cells ◽  
Endocytic Pathway ◽  
Great Promise ◽  
Biological Processes ◽  
Temporal Precision ◽  
Single Molecule Level ◽  
Cellular Processes ◽  
Cellular Environment ◽  
Biological Studies

Studying biological processes and mechanics in living cells is challenging but highly rewarding. Recent advances in experimental techniques have provided numerous ways to investigate cellular processes and mechanics of living cells. However, most of existing techniques for biomechanics are limited to experiments outside or on the membrane of cells, due to the difficulties in physically accessing the interior of living cells. On the other hand, nanomaterials, such as fluorescent quantum dots (QDs) and magnetic nanoparticles, have shown great promise to overcome such limitations due to their small sizes and excellent functionalities, including bright and stable fluorescence and remote manipulability. However, except a few systems, the use of nanoparticles has been limited to the study of biological studies on cell membranes or related to endocytosis, because of the difficulty of delivering dispersed and single nanoparticles into living cells. Various strategies have been explored, but delivered nanoparticles are often trapped in the endocytic pathway or form aggregates in the cytoplasm, limiting their further use. Here we show a nanoscale direct delivery method, named nanomechanochemical delivery, where we manipulate a nanotube-based nanoneedle, carrying “cargo” (QDs in this study), to mechanically penetrate the cell membrane, access specific areas inside cells, and release the cargo [1]. We selectively delivered well-dispersed QDs into either the cytoplasm or the nucleus of living cells. We quantified the dynamics of the delivered QDs by single-molecule tracking and demonstrated the applicability of the QDs as a nanoscale probe for studying nanomechanics inside living cells (by using the biomicrorhology method), revealing the biomechanical heterogeneity of the cellular environment. This method may allow new strategies for studying biological processes and mechanics in living cells with spatial and temporal precision, potentially at the single-molecule level.

Interfacial Electron Transfer from CdSe/ZnS Quantum Dots to TiO2Nanoparticles: Linker Dependence at Single Molecule Level

2013 ◽  
Vol 25 (4) ◽  
pp. 1064-1073 ◽  
Author(s):  
Yu-Pin Chang ◽  
Po-Yu Tsai ◽  
Hsin-Lung Lee ◽  
King-Chuen Lin
Keyword(s):  
Quantum Dots ◽  
Electron Transfer ◽  
Single Molecule ◽  
Interfacial Electron Transfer ◽  
Single Molecule Level

Auger Ionization Beats Photo-Oxidation of Semiconductor Quantum Dots: Extended Stability of Single-Molecule Photoluminescence

2015 ◽  
Vol 127 (13) ◽  
pp. 3964-3968 ◽  
Author(s):  
Shin-ichi Yamashita ◽  
Morihiko Hamada ◽  
Shunsuke Nakanishi ◽  
Hironobu Saito ◽  
Yoshio Nosaka ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Single Molecule ◽  
Semiconductor Quantum Dots ◽  
Photo Oxidation

Auger Ionization Beats Photo-Oxidation of Semiconductor Quantum Dots: Extended Stability of Single-Molecule Photoluminescence

2015 ◽  
Vol 54 (13) ◽  
pp. 3892-3896 ◽  
Author(s):  
Shin-ichi Yamashita ◽  
Morihiko Hamada ◽  
Shunsuke Nakanishi ◽  
Hironobu Saito ◽  
Yoshio Nosaka ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Single Molecule ◽  
Semiconductor Quantum Dots ◽  
Photo Oxidation

scholarly journals KIF13A motors are regulated by Rab22A to function as weak dimers inside the cell

2021 ◽  
Vol 7 (6) ◽  
pp. eabd2054
Author(s):  
Nishaben M. Patel ◽  
Meenakshi Sundaram Aravintha Siva ◽  
Ruchi Kumari ◽  
Dipeshwari J. Shewale ◽  
Ashim Rai ◽  
...  
Keyword(s):  
Single Molecule ◽  
Regulatory Mechanism ◽  
Coiled Coil ◽  
Recycling Endosomes ◽  
Single Molecule Level ◽  
Cellular Processes ◽  
Membrane Tubulation ◽  
Guanosine Triphosphatase ◽  
Neck Coil ◽  
Unique Mechanism

Endocytic recycling is a complex itinerary, critical for many cellular processes. Membrane tubulation is a hallmark of recycling endosomes (REs), mediated by KIF13A, a kinesin-3 family motor. Understanding the regulatory mechanism of KIF13A in RE tubulation and cargo recycling is of fundamental importance but is overlooked. Here, we report a unique mechanism of KIF13A dimerization modulated by Rab22A, a small guanosine triphosphatase, during RE tubulation. A conserved proline between neck coil–coiled-coil (NC-CC1) domains of KIF13A creates steric hindrance, rendering the motors as inactive monomers. Rab22A plays an unusual role by binding to NC-CC1 domains of KIF13A, relieving proline-mediated inhibition and facilitating motor dimerization. As a result, KIF13A motors produce balanced motility and force against multiple dyneins in a molecular tug-of-war to regulate RE tubulation and homeostasis. Together, our findings demonstrate that KIF13A motors are tuned at a single-molecule level to function as weak dimers on the cellular cargo.

scholarly journals Characterizing the Quantum-Confined Stark Effect in Semiconductor Quantum Dots and Nanorods for Single-Molecule Electrophysiology

ACS Photonics ◽  
2018 ◽  
Vol 5 (12) ◽  
pp. 4788-4800 ◽  
Author(s):  
Yung Kuo ◽  
Jack Li ◽  
Xavier Michalet ◽  
Alexey Chizhik ◽  
Noga Meir ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Single Molecule ◽  
Stark Effect ◽  
Semiconductor Quantum Dots ◽  
Quantum Confined Stark Effect ◽  
Quantum Confined

scholarly journals Studies of bacterial topoisomerases I and III at the single-molecule level

2013 ◽  
Vol 41 (2) ◽  
pp. 571-575 ◽  
Author(s):  
Ksenia Terekhova ◽  
John F. Marko ◽  
Alfonso Mondragón
Keyword(s):  
Single Molecule ◽  
Topoisomerase I ◽  
Dna Topology ◽  
Biological Molecules ◽  
Single Molecule Level ◽  
Cellular Processes ◽  
Topoisomerase Iii ◽  
Type Ia ◽  
Dna Strand

Topoisomerases are the enzymes responsible for maintaining the supercoiled state of DNA in the cell and also for many other DNA-topology-associated reactions. Type IA enzymes alter DNA topology by breaking one DNA strand and passing another strand or strands through the break. Although all type IA topoisomerases are related at the sequence, structure and mechanism levels, different type IA enzymes do not participate in the same cellular processes. We have studied the mechanism of DNA relaxation by Escherichia coli topoisomerases I and III using single-molecule techniques to understand their dissimilarities. Our experiments show important differences at the single-molecule level, while also recovering the results from bulk experiments. Overall, topoisomerase III relaxes DNA using fast processive runs followed by long pauses, whereas topoisomerase I relaxes DNA through slow processive runs followed by short pauses. These two properties combined give rise to the overall relaxation rate, which is higher for topoisomerase I than for topoisomerase III, as expected from many biochemical observations. The results help us to understand better the role of these two topoisomerases in the cell and also serve to illustrate the power of single-molecule experiments to uncover new functional characteristics of biological molecules.

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