Cell-Directed Localization and Orientation of a Functional Foreign Transmembrane Protein within a Silica Nanostructure

Abstract

A simple procedure for introducing functional exogenous membrane-bound proteins to viable cells encapsulated within a lipid templated silica nanostructure is described. In one method, bacteriorhodopsin (bR) was added directly to a Saccharomyces cerevisiae solution along with short zwitterionic diacylphosphatidylcholines (diC(6) PC) and mixed with equal volumes of a sol precursor solution. Alternatively, bR was first incorporated into liposomes (bR-proteoliposomes) and then added to an S. cerevisiae solution with diC(6) PC, and this was followed by mixing with sol precursor solution. Films prepared from bR added directly to diC(6) PC resulted in bR localization near S. cerevisiae cells in a disordered and diffuse fashion, while films prepared from bR-proteoliposomes added to the diC(6) PC/yeast solution resulted in preferential localization of bR near yeast cell surfaces, forming bR-containing multilayer vesicles. Importantly, bR introduced via proteoliposomes was observed to modulate pH gradients developed at the cell surface, demonstrating both retained functionality and preferential orientation. Localization of liposome lipid or bR did not occur around neutrally charged latex beads acting as cell surrogates, demonstrating that living cells actively organize the multilayered lipid during evaporation-induced self-assembly. We expect this simple procedure for introducing functional and oriented membrane-bound proteins to the surface of cells to be general and adaptable to other membrane-bound proteins. This advance may prove useful in fundamental studies of membrane protein function and cell-cell signaling and in imparting non-native characteristics to arbitrary cells.

Applications of advanced hybrid organic–inorganic nanomaterials: from laboratory to market

“…In that case, preserving the viability of cells within sol-gel derived hybrid matrices appears to be a real challenge. Studies pioneered by Livage et al 331 and confirmed by other groups [332][333][334][335] indicating that encapsulated bacteria (E. coli) can survive the gelation procedure and remain able to continue normal metabolic activity within the gel matrix are opening new promising avenues in this field. 326-332…”

Silica bioreplication preserves three-dimensional spheroid structures of human pluripotent stem cells and HepG2 cells

“…The first in vitro biomimetic synthesis of silica was reported more than a decade ago 19 . Later this biomimetic approach was used in producing silica nanomaterials 20 21 22 and cell-directed silica biocomposites 17 23 24 25 26 27 . SBR is a self-limiting biomolecular surface-directed silica assembly process that results in nearly an exact replica of external and internal cellular 17 27 , tissue, and organism-scale 18 features in nanometre (<10 nm) thick silica layers.…”

Encapsulation of cells within silica matrixes: Towards a new advance in the conception of living hybrid materials

“…The authors suggest that these molecules maintain bacteria in a stationary state and modify their metabolism in order to enhance cell resistance to the external stresses [58]. Recently, a promising pathway to cell encapsulation has been reported by Brinker et al [60][61][62]. Different bacteria cell lines (and even yeasts) have been incorporated within nanostructured silica films formed by an evaporation-induced self assembly approach (Fig.…”