Controllable Shrinking and Shaping of Glass Nanocapillaries under Electron Irradiation

The ability to reshape nanopores and observe their shrinkage under an electron microscope is a powerful and novel technique. It increases the sensitivity of the resistive pulse sensing and enables to detect very short and small molecules. However, this has not yet been shown for glass nanocapillaries. In contrast to their solid-state nanopore counterparts, nanocapillaries are cheap, easily fabricated and in the production do not necessitate clean room facilities. We show for the first time that quartz nanocapillaries can be shrunken under a scanning electron microscope beam. Since the shrinking is caused by the thermal heating of the electrons, increasing the beam current increases the shrink rate. Higher acceleration voltage on the contrary increases the electron penetration depth and reduces the electron density causing slower shrinkage. This allows us to fine control the shrink rate and to stop the shrinking process at any desired diameter. We show that a shrunken nanocapillary detects DNA translocation with six times higher signal amplitudes than an unmodified nanocapillary. This will open a new path to detect small and short molecules such as proteins or RNA with nanocapillaries

Probing the size of proteins with glass nanopores

Single molecule studies using nanopores have gained attention due to the ability to sense single molecules in aqueous solution without the need to label them. In this study, short DNA molecules and proteins were detected with glass nanopores, whose sensitivity was enhanced by electron reshaping which decreased the nanopore diameter and created geometries with a reduced sensing length. Further, proteins having molecular weights (MW) ranging from 12 kDa to 480 kDa were detected, which showed that their corresponding current peak amplitude changes according to their MW. In the case of the 12 kDa ComEA protein, its DNA-binding properties to an 800 bp long DNA molecule was investigated. Moreover, the influence of the pH on the charge of the protein was demonstrated by showing a change in the translocation direction. This work emphasizes the wide spectrum of detectable molecules using nanopores from glass nanocapillaries, which stand out because of their inexpensive, lithography-free, and rapid manufacturing proces

Probing the size of proteins with glass nanopores

Single molecule studies using nanopores have gained attention due to the ability to sense single molecules in aqueous solution without the need to label them. In this study, short DNA molecules and proteins were detected with glass nanopores, whose sensitivity was enhanced by electron reshaping which decreased the nanopore diameter and created geometries with a reduced sensing length. Further, proteins having molecular weights (MW) ranging from 12 kDa to 480 kDa were detected, which showed that their corresponding current peak amplitude changes according to their MW. In the case of the 12 kDa ComEA protein, its DNA-binding properties to an 800 bp long DNA molecule was investigated. Moreover, the influence of the pH on the charge of the protein was demonstrated by showing a change in the translocation direction. This work emphasizes the wide spectrum of detectable molecules using nanopores from glass nanocapillaries, which stand out because of their inexpensive, lithography-free, and rapid manufacturing process

MicroMotility: State of the art, recent accomplishments and perspectives on the mathematical modeling of bio-motility at microscopic scales

Mathematical modeling and quantitative study of biological motility (in particular, of motility at microscopic scales) is producing new biophysical insight and is offering opportunities for new discoveries at the level of both fundamental science and technology. These range from the explanation of how complex behavior at the level of a single organism emerges from body architecture, to the understanding of collective phenomena in groups of organisms and tissues, and of how these forms of swarm intelligence can be controlled and harnessed in engineering applications, to the elucidation of processes of fundamental biological relevance at the cellular and sub-cellular level. In this paper, some of the most exciting new developments in the fields of locomotion of unicellular organisms, of soft adhesive locomotion across scales, of the study of pore translocation properties of knotted DNA, of the development of synthetic active solid sheets, of the mechanics of the unjamming transition in dense cell collectives, of the mechanics of cell sheet folding in volvocalean algae, and of the self-propulsion of topological defects in active matter are discussed. For each of these topics, we provide a brief state of the art, an example of recent achievements, and some directions for future research

Controllable Shrinking and Shaping of Glass Nanocapillaries under Electron Irradiation

The ability to reshape nanopores and observe their shrinkage under an electron microscope is a powerful and novel technique. It increases the sensitivity of the resistive pulse sensing and enables to detect very short and small molecules. However, this has not yet been shown for glass nanocapillaries. In contrast to their solid-state nanopore counterparts, nanocapillaries are cheap, easily fabricated and in the production do not necessitate clean room facilities. We show for the first time that quartz nanocapillaries can be shrunken under a scanning electron microscope beam. Since the shrinking is caused by the thermal heating of the electrons, increasing the beam current increases the shrink rate. Higher acceleration voltage on the contrary increases the electron penetration depth and reduces the electron density causing slower shrinkage. This allows us to fine control the shrink rate and to stop the shrinking process at any desired diameter. We show that a shrunken nanocapillary detects DNA translocation with six times higher signal amplitudes than an unmodified nanocapillary. This will open a new path to detect small and short molecules such as proteins or RNA with nanocapillaries

Controllable Shrinking and Shaping of Glass Nanocapillaries under Electron Irradiation

The ability to reshape nanopores and observe their shrinkage under an electron microscope is a powerful and novel technique. It increases the sensitivity of the resistive pulse sensing and enables to detect very short and small molecules. However, this has not yet been shown for glass nanocapillaries. In contrast to their solid-state nanopore counterparts, nanocapillaries are cheap, easily fabricated and in the production do not necessitate clean room facilities. We show for the first time that quartz nanocapillaries can be shrunken under a scanning electron microscope beam. Since the shrinking is caused by the thermal heating of the electrons, increasing the beam current increases the shrink rate. Higher acceleration voltage on the contrary increases the electron penetration depth and reduces the electron density causing slower shrinkage. This allows us to fine control the shrink rate and to stop the shrinking process at any desired diameter. We show that a shrunken nanocapillary detects DNA translocation with six times higher signal amplitudes than an unmodified nanocapillary. This will open a new path to detect small and short molecules such as proteins or RNA with nanocapillaries

Controllable Shrinking and Shaping of Glass Nanocapillaries under Electron Irradiation

The ability to reshape nanopores and observe their shrinkage under an electron microscope is a powerful and novel technique. It increases the sensitivity of the resistive pulse sensing and enables to detect very short and small molecules. However, this has not yet been shown for glass nanocapillaries. In contrast to their solid-state nanopore counterparts, nanocapillaries are cheap, easily fabricated and in the production do not necessitate clean room facilities. We show for the first time that quartz nanocapillaries can be shrunken under a scanning electron microscope beam. Since the shrinking is caused by the thermal heating of the electrons, increasing the beam current increases the shrink rate. Higher acceleration voltage on the contrary increases the electron penetration depth and reduces the electron density causing slower shrinkage. This allows us to fine control the shrink rate and to stop the shrinking process at any desired diameter. We show that a shrunken nanocapillary detects DNA translocation with six times higher signal amplitudes than an unmodified nanocapillary. This will open a new path to detect small and short molecules such as proteins or RNA with nanocapillaries