Atomic force microscopy-based characterization and design of biointerfaces
TL;DR: Basic and advanced AFM-related approaches are surveyed and their unique advantages and limitations in imaging, sensing, parameterizing and designing biointerfaces using AFM techniques are discussed.
Abstract: Atomic force microscopy (AFM)-based methods have matured into a powerful nanoscopic platform, enabling the characterization of a wide range of biological and synthetic biointerfaces ranging from tissues, cells, membranes, proteins, nucleic acids and functional materials. Although the unprecedented signal-to-noise ratio of AFM enables the imaging of biological interfaces from the cellular to the molecular scale, AFM-based force spectroscopy allows their mechanical, chemical, conductive or electrostatic, and biological properties to be probed. The combination of AFM-based imaging and spectroscopy structurally maps these properties and allows their 3D manipulation with molecular precision. In this Review, we survey basic and advanced AFM-related approaches and evaluate their unique advantages and limitations in imaging, sensing, parameterizing and designing biointerfaces. It is anticipated that in the next decade these AFM-related techniques will have a profound influence on the way researchers view, characterize and construct biointerfaces, thereby helping to solve and address fundamental challenges that cannot be addressed with other techniques. Atomic force microscopy (AFM)-based approaches enable the characterization and manipulation of biological and synthetic biointerfaces, including tissues, cells, membranes, proteins, nucleic acid and functional materials. In this Review, the advantages and limitations of imaging, sensing, parameterizing and designing biointerfaces using AFM techniques are discussed.
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01 Jan 2019
TL;DR: The potential of combining AFM with complementary techniques, including optical microscopy and spectroscopy of mechanosensitive fluorescent constructs, super-resolution microscopy, the patch clamp technique and the use of microstructured and fluidic devices to characterize the 3D distribution of mechanical responses within biological systems and to track their morphology and functional state as discussed by the authors.
Abstract: Mechanobiology emerges at the crossroads of medicine, biology, biophysics and engineering and describes how the responses of proteins, cells, tissues and organs to mechanical cues contribute to development, differentiation, physiology and disease. The grand challenge in mechanobiology is to quantify how biological systems sense, transduce, respond and apply mechanical signals. Over the past three decades, atomic force microscopy (AFM) has emerged as a key platform enabling the simultaneous morphological and mechanical characterization of living biological systems. In this Review, we survey the basic principles, advantages and limitations of the most common AFM modalities used to map the dynamic mechanical properties of complex biological samples to their morphology. We discuss how mechanical properties can be directly linked to function, which has remained a poorly addressed issue. We outline the potential of combining AFM with complementary techniques, including optical microscopy and spectroscopy of mechanosensitive fluorescent constructs, super-resolution microscopy, the patch clamp technique and the use of microstructured and fluidic devices to characterize the 3D distribution of mechanical responses within biological systems and to track their morphology and functional state. Mechanobiology describes how biological systems respond to mechanical stimuli. This Review surveys basic principles, advantages and limitations of applying and combining atomic force microscopy-based modalities with complementary techniques to characterize the morphology, mechanical properties and functional response of complex biological systems to mechanical cues.
387 citations
01 Nov 2018
TL;DR: The potential of combining AFM with complementary techniques, including optical microscopy and spectroscopy of mechanosensitive fluorescent constructs, super-resolution microscopy, the patch clamp technique and the use of microstructured and fluidic devices to characterize the 3D distribution of mechanical responses within biological systems are outlined.
Abstract: Mechanobiology emerges at the crossroads of medicine, biology, biophysics and engineering and describes how the responses of proteins, cells, tissues and organs to mechanical cues contribute to development, differentiation, physiology and disease. The grand challenge in mechanobiology is to quantify how biological systems sense, transduce, respond and apply mechanical signals. Over the past three decades, atomic force microscopy (AFM) has emerged as a key platform enabling the simultaneous morphological and mechanical characterization of living biological systems. In this Review, we survey the basic principles, advantages and limitations of the most common AFM modalities used to map the dynamic mechanical properties of complex biological samples to their morphology. We discuss how mechanical properties can be directly linked to function, which has remained a poorly addressed issue. We outline the potential of combining AFM with complementary techniques, including optical microscopy and spectroscopy of mechanosensitive fluorescent constructs, super-resolution microscopy, the patch clamp technique and the use of microstructured and fluidic devices to characterize the 3D distribution of mechanical responses within biological systems and to track their morphology and functional state.Mechanobiology describes how biological systems respond to mechanical stimuli. This Review surveys basic principles, advantages and limitations of applying and combining atomic force microscopy-based modalities with complementary techniques to characterize the morphology, mechanical properties and functional response of complex biological systems to mechanical cues.Key pointsThe versatile functions of biological systems ranging from molecules, cells and cellular systems to living organisms are governed by their mechanical properties and ability to sense mechanical cues and respond to them.Atomic force microscopy (AFM)-based approaches provide multifunctional nanotools to measure a wide variety of mechanical properties of living systems and to apply to them well-defined mechanical cues.AFM allows us to apply and measure forces from the piconewton to the micronewton range on spatially defined areas with sizes ranging from the sub-nanometre to several tens of micrometres.Mechanical parameters characterized by AFM include force, pressure, tension, adhesion, friction, elasticity, viscosity and energy dissipation.The mechanical parameters of complex biological systems can be structurally mapped, with a spatial resolution ranging from millimetres to sub-nanometres and at kinetic ranges from hours to milliseconds.AFM can be combined with various complementary methods to characterize a multitude of mechanical, functional and morphological properties and responses of complex biological systems.
271 citations
TL;DR: In this paper, the authors used a cell surface-binding assay, a kinetics study, a single-molecule technique, and a computational method to investigate the interaction between these RBD (mutations) and ACE2.
Abstract: SARS-CoV-2 has been spreading around the world for the past year. Recently, several variants such as B.1.1.7 (alpha), B.1.351 (beta), and P.1 (gamma), which share a key mutation N501Y on the receptor-binding domain (RBD), appear to be more infectious to humans. To understand the underlying mechanism, we used a cell surface-binding assay, a kinetics study, a single-molecule technique, and a computational method to investigate the interaction between these RBD (mutations) and ACE2. Remarkably, RBD with the N501Y mutation exhibited a considerably stronger interaction, with a faster association rate and a slower dissociation rate. Atomic force microscopy (AFM)-based single-molecule force microscopy (SMFS) consistently quantified the interaction strength of RBD with the mutation as having increased binding probability and requiring increased unbinding force. Molecular dynamics simulations of RBD-ACE2 complexes indicated that the N501Y mutation introduced additional π-π and π-cation interactions that could explain the changes observed by force microscopy. Taken together, these results suggest that the reinforced RBD-ACE2 interaction that results from the N501Y mutation in the RBD should play an essential role in the higher rate of transmission of SARS-CoV-2 variants, and that future mutations in the RBD of the virus should be under surveillance.
199 citations
TL;DR: A spontaneous formation of peculiar "shish kebab" nanostructures with the periodic arrangement of silk fibroin domains along straight segments of cellulose nanofibers is reported, enabling the ultrathin membrane to possess open, transparent, mechanically robust interlocked networks with high mechanical performance.
Abstract: The construction of multilength scaled hierarchical nanostructures from diverse natural components is critical in the progress toward all-natural nanocomposites with structural robustness and versatile added functionalities. Here, we report a spontaneous formation of peculiar “shish kebab” nanostructures with the periodic arrangement of silk fibroin domains along straight segments of cellulose nanofibers. We suggest that the formation of these shish kebab nanostructures is facilitated by the preferential organization of heterogeneous (β-sheets and amorphous silk) domains along the cellulose nanofiber driven by modulated axial distribution of crystalline planes, hydrogen bonding, and hydrophobic interactions as suggested by all-atom molecular dynamic simulations. Such shish kebab nanostructures enable the ultrathin membrane to possess open, transparent, mechanically robust interlocked networks with high mechanical performance with up to 30 GPa in stiffness and 260 MPa in strength. These nanoporous robust m...
99 citations
TL;DR: The field of vascular biology now realize that an intricate analysis of endothelial signaling mechanisms requires complex in vitro systems to mimic in vivo conditions and advancements in endothelial cell culture models designed to better mimic the in vivo vascular microenvironment are discussed.
Abstract: Blood and lymphatic vessels are lined by endothelial cells which constantly interact with their luminal and abluminal extracellular environments. These interactions confer physical forces on the endothelium, such as shear stress, stretch and stiffness, to mediate biological responses. These physical forces are often altered during disease, driving abnormal endothelial cell behavior and pathology. Therefore, it is critical that we understand the mechanisms by which endothelial cells respond to physical forces. Traditionally, endothelial cells in culture are grown in the absence of flow on stiff substrates such as plastic or glass. These cells are not subjected to the physical forces that endothelial cells endure in vivo, thus the results of these experiments often do not mimic those observed in the body. The field of vascular biology now realize that an intricate analysis of endothelial signaling mechanisms requires complex in vitro systems to mimic in vivo conditions. Here, we will review what is known about the mechanical forces that guide endothelial cell behavior and then discuss the advancements in endothelial cell culture models designed to better mimic the in vivo vascular microenvironment. A wider application of these technologies will provide more biologically relevant information from cultured cells which will be reproducible to conditions found in the body.
91 citations
Cites background from "Atomic force microscopy-based chara..."
...Another frequently used natural hydrogel, Matrigel, which is a heterogenic mixture of various ECM proteins, was found to have a stiffness of approximately 0.45 kPa when measured with AFM in an aqueous, temperature controlled environment (Soofi et al., 2009)....
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...Therefore, these data underscore the importance of analyzing mechanical properties of individual vessel components using microscale techniques, such as Atomic Force Microscopy (AFM) (Alsteens et al., 2017; Frye et al., 2018) and Scanning Ion Conductance Microscopy (SICM) (Schaffer, 2013)....
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References
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TL;DR: The atomic force microscope as mentioned in this paper is a combination of the principles of the scanning tunneling microscope and the stylus profilometer, which was proposed as a method to measure forces as small as 10-18 N. As one application for this concept, they introduce a new type of microscope capable of investigating surfaces of insulators on an atomic scale.
Abstract: The scanning tunneling microscope is proposed as a method to measure forces as small as 10-18 N. As one application for this concept, we introduce a new type of microscope capable of investigating surfaces of insulators on an atomic scale. The atomic force microscope is a combination of the principles of the scanning tunneling microscope and the stylus profilometer. It incorporates a probe that does not damage the surface. Our preliminary results in air demonstrate a lateral resolution of 30 A and a vertical resolution less than 1 A.
12,344 citations
TL;DR: Probing the various interfaces of nanoparticle/biological interfaces allows the development of predictive relationships between structure and activity that are determined by nanomaterial properties such as size, shape, surface chemistry, roughness and surface coatings.
Abstract: Rapid growth in nanotechnology is increasing the likelihood of engineered nanomaterials coming into contact with humans and the environment. Nanoparticles interacting with proteins, membranes, cells, DNA and organelles establish a series of nanoparticle/biological interfaces that depend on colloidal forces as well as dynamic biophysicochemical interactions. These interactions lead to the formation of protein coronas, particle wrapping, intracellular uptake and biocatalytic processes that could have biocompatible or bioadverse outcomes. For their part, the biomolecules may induce phase transformations, free energy releases, restructuring and dissolution at the nanomaterial surface. Probing these various interfaces allows the development of predictive relationships between structure and activity that are determined by nanomaterial properties such as size, shape, surface chemistry, roughness and surface coatings. This knowledge is important from the perspective of safe use of nanomaterials.
6,075 citations
TL;DR: The artificial synthesis of a number of the components of the vitamin B complex has made available pure crystalline material in large amounts for clinical research, and thus a milestone in the history of these affections has been passed.
Abstract: AFFECTIONS of the nervous system which result from inadequate nutrition have assumed an increasingly important position through the rapid accumulation of clinical, experimental, and pathological data. The artificial synthesis of a number of the components of the vitamin B complex has made available pure crystalline material in large amounts for clinical research, and thus a milestone in the history of these affections has been passed. It now seems appropriate to review and summarize the knowledge of these important substances. To evaluate the status of a nutritional deficiency in man is difficult. As a rule the patient induces his own disease and provides a deficiency that is not quantitatively measurable, but frequently clinical and laboratory evaluations are attempted. Both the laboratory method and the clinical method have certain advantages. Mice are not yet men and until they are the work coming -from the study of human beings is essential. Since the experience of investigators working with animals may often point the way for clinical research, we have interspersed in this review a few of the pertinent studies on the effect of nutritional deficiency on the nervous system of animals. A scheme for illustrating the multiple factors of the vitamin B complex is given in Fig. 1. To date the following portions of the vitamin B complex have been isolated and synthesized in amounts sufficient to allow for clinical trial: thiamin hydrochloride, nicotinic acid, riboflavin, and 2-methyl, 3-hydroxy, 4, 5-di (hydroxymethyl) pyridine. The deficiencies of these substances as they apply to the nervous system of man will be discussed briefly.
4,261 citations
TL;DR: The atomic force microscope (AFM) is not only used to image the topography of solid surfaces at high resolution but also to measure force-versus-distance curves as discussed by the authors, which provide valuable information on local material properties such as elasticity, hardness, Hamaker constant, adhesion and surface charge densities.
3,281 citations
TL;DR: Single-molecule atomic force microscopy was used to investigate the mechanical properties of titin, the giant sarcomeric protein of striated muscle, and refolding of immunoglobulin domains was observed.
Abstract: Single-molecule atomic force microscopy (AFM) was used to investigate the mechanical properties of titin, the giant sarcomeric protein of striated muscle. Individual titin molecules were repeatedly stretched, and the applied force was recorded as a function of the elongation. At large extensions, the restoring force exhibited a sawtoothlike pattern, with a periodicity that varied between 25 and 28 nanometers. Measurements of recombinant titin immunoglobulin segments of two different lengths exhibited the same pattern and allowed attribution of the discontinuities to the unfolding of individual immunoglobulin domains. The forces required to unfold individual domains ranged from 150 to 300 piconewtons and depended on the pulling speed. Upon relaxation, refolding of immunoglobulin domains was observed.
2,959 citations