Precision Assembly of Complex Cellular Microenvironments using Holographic Optical Tweezers

Abstract

The accurate study of cellular microenvironments is limited by the lack of technologies that can manipulate cells in 3D at a sufficiently small length scale. The ability to build and manipulate multicellular microscopic structures will facilitate a more detailed understanding of cellular function in fields such as developmental and stem cell biology. We present a holographic optical tweezers based technology to accurately generate bespoke cellular micro-architectures. Using embryonic stem cells, 3D structures of varying geometries were created and stabilized using hydrogels and cell-cell adhesion methods. Control of chemical microenvironments was achieved by the temporal release of specific factors from polymer microparticles positioned within these constructs. Complex co-culture micro-environmental analogues were also generated to reproduce structures found within adult stem cell niches. The application of holographic optical tweezers-based micromanipulation will enable novel insights into biological microenvironments by allowing researchers to form complex architectures with sub-micron precision of cells, matrices and molecules.

Surface acoustic waves induced micropatterning of cells in gelatin methacryloyl (GelMA) hydrogels

“…Finally, optical tweezers have also been employed to generate various patterns of cells in hydrogels by controlling their chemical microenvironments. This technique, however, does not allow for the rapid organization of large populations of cells [27]. …”

Assembly of Topographical Micropatterns with Optoelectronic Tweezers

“…These methods permit unparalleled flexibility in user determination of feature size and spatial positioning, but they are expensive, require a cleanroom (and are not accessible to all users), and have some limitations on throughput (particularly for e-beam lithography). [22][23][24][25] These techniques, in which patterns of 3D particles are assembled in a fluidic environment and are later dried for use in TMP applications, are creative and interesting, and preserve many of the advantages of the canonical methods while allowing for accessible, cleanroom-free operation. [12,13] These techniques are useful, but they also rely on expensive and specialized tools and well-trained personnel, and can have limited throughput.…”

Optical Tweezers in Biotechnology

“…As an emerging optical technology, holographic optical tweezers can trap and manipulate a large number of particles, showing great application prospects in the fields of particle assembly and construction of three-dimensional cell microstructure (Figure 3). For example, Glen R. Kirkham et al of the United Kingdom used holographic optical tweezers to assemble one-, two-, and three-dimensional embryonic stem cell array structures (as shown in Figure 4) to provide a new means to study the directed differentiation of stem cells [16]. Moreover, Jesacher and his colleagues from Austria regulated the amplitude and phase of the incident light field through a liquid crystal spatial light modulator, which not only realized trapping potential wells of special shapes such as line, cross, circle, and rectangle but also controlled the microparticle movement along a specific path.…”

“…In the future, the fiber-based optical tweezers may integrate multiple functions on a single-fiber probe, as shown in Figure 6, such as simultaneously capturing, transporting, sorting, stretching, deforming, and rotating various cells and pathogens in the microfluidics or living blood. Bright-field optical micrographs and confocal fluorescence micrographs of one-, two-, and three-dimensional microarray structures of embryonic stem cells assembled by holographic optical tweezers [16].…”