Single Cell Encapsulation
Cells are encapsulated individually within thin and tough shells in a cytocompatible manner, by mimicking the structure of bacterial endospores that survive under hostile conditions. The 3-dimensional ‘cell-in-shell’ structures—coined ‘artificial spores’—enable modulation and control over cellular metabolism, such as control of cell division, resistance to external stresses, and surface-functionalizability, providing a useful platform for applications, including cell-based sensors, cell therapy, regenerative medicine, as well as for fundamental studies on cellular metabolism at the single-cell level and cell-to-cell communications.
Multiple-cells can be confined in 3-dimensional microcapsules that physically isolate them from the outside. By introducing an ultrathin and robust shell on the surface of a cell-laden module, multiple-cells can be isolated completely and achieve notable characteristics, such as controlled cell-division, and survivability from external hazards. The encapsulated cells survive and are biologically functional within the capsules, suggesting various applications in cellular medicine, probiotics packaging, as well as providing research platforms for studying microbial communications, including quorum sensing.
Many aspects of neurons and neuronal behavior are affected by the size, shape, and pattern of the physical features of the environment. A recent increase in the use of nanometric topographies, due to improved fabrication techniques, has resulted in new findings on neuronal behavior and development. Topography has been shown to affect neurons in variety of unique ways, not only being able to guide the direction of neurite and axon outgrowth, but also increasing the length of neurites and the rate at which neurites develop in undifferentiated neurons. Factors such as neuron adhesion, neurite alignment, and even the rate of neurite formation have all been highlighted through nanotopographies as complex phenomena that are driven by intricate intracellular mechanisms. Nanotopographies are suitable platforms, not only for fundamental studies on neuronal development, but also in practical applications, including multi-electrode array devices and neuro-regenerative medicine.
Neuronal Metabolic Engineering
Glycosylation, which gives diversity to the roles and functions of biomaterials, is an essential process in cellular system, and in particular, the nervous system glycoconjugates on surfaces modulate a multitude of neuronal functions, such as neurogenesis, synaptic plasticity and neurite development as well as fundamental cellular functions. However, understanding of the roles of the glycoconjugates on neuronal cell surfaces is lacking. Therefore, using unnatural sugars as chemical reporters, the external glycans of primary neurons were metabolically labeled and observed spatiotemporally with fluorescence dyes. The metabolic engineering of neurons is critical to understanding the mechanisms behind neurite outgrowth, axonogenesis, synaptogenesis, as well as neuron metabolism.
Organic coatings refer to a coating process with non-metallic content, mainly with organic molecules. The resultant organic film is more flexible and easily functionalizable than inorganic/metallic films. Living cell surfaces can also be coated with organic films consisting of biocompatible organic molecules, such as natural polysaccharides, proteins, and synthetic polymers. Many physical/chemical surface properties (e.g. charge, roughness, wettability, etc.) can be controlled via organic coatings, when applied to cell surfaces. Organic films can protect cells from a harmful environment and even act as an immunobarrier for cell therapy.
Surface-initiated polymerization (SIP) has plenty of uses to make functional organic surfaces by chain radical reaction of organic monomers. This grafting-from polymerization has many advantages, such as ease of thickness control, dense polymer brushes, and simple reaction conditions. The method has been used for several functional coatings such as anti-bacterial, super-hydrophobic, and highly sensitive/selective coatings. Recently, SIP has been applied to not only the fabrication of 2D surfaces for functional coatings, but also diverse biomedical applications.