Optical trapping in vivo: theory, practice, and applications

Abstract

Since the time of their introduction, optical tweezers (OTs) have grown to be a powerful tool in the hands of biologists. OTs use highly focused laser light to guide, manipulate, or sort target objects, typically in the nanoscale to microscale range. OTs have been particularly useful in making quantitative measurements of forces acting in cellular systems; they can reach inside living cells and be used to study the mechanical properties of the fluids and structures that they contain. As all the measurements are conducted without physically contacting the system under study, they also avoid complications related to contamination and tissue damage. From the manipulation of fluorescent nanodiamonds to chromosomes, cells, and free-swimming bacteria, OTs have now been extended to challenging biological systems such as the vestibular system in zebrafish. Here, we will give an overview of OTs, the complications that arise in carrying out OTs in vivo, and specific OT methods that have been used to address a range of otherwise inaccessible biological questions.

Optical Tweezers in Studies of Red Blood Cells

“…Nowadays, the breathtaking prospects of the revolutionary OTs in living cell manipulation, single-molecule biophysical analysis, cell mechanical characterization and quantitative biomechanics evaluation in sophisticated biological processes have found abundant applications in studying molecular motors, RNA folding/unfolding, intercellular communications, etc. [27,[30][31][32]. The innumerable applications of OTs in the last two decades have been thoroughly reviewed with respect to cell biology and living systems [26,27,33,34], microrheology and biorheology studies [25,35], bio-forces and force-dependent biological processes [2,4,36,37], nanotechnology [3,38] and noncontact particle assembly or nanofabrication [39,40].…”

Optical Tweezers Approaches for Probing Multiscale Protein Mechanics and Assembly

“…OT have the broadest applicability in probing the mechanics of protein assemblies at various hierarchies of scale: they offer advantages of high spatial, temporal and force resolution for SFMS, and the ability to passively and actively probe microscale mechanics at prescribed locations within three-dimensional protein networks and even inside living cells ( Arbore et al, 2019 ; Favre-Bulle Itia et al, 2019 ). This ability to extract force and displacement information across a wide span of system size scales with a single experimental approach facilitates meaningful comparisons of mechanics of proteins at different levels of assembly.…”

Opto-Thermoelectric Tweezers: Principles and Applications

“…Various strategies were proposed to address these limitations of conventional optical tweezers [17][18][19][20][21]. For instance, plasmonic tweezers exploit the strong electromagnetic field enhancement in metallic nanostructures to achieve near-field trapping in plasmonic hotspots [22][23][24], which enable manipulation of nanoparticles and molecules beyond the diffraction limit with a reduced operational power [17].…”