Temporary Single-Cell Coating for Bioprocessing with a Cationic Polymer

Abstract

Temporary single-cell coating is a useful tool for cell processing, allowing manipulation of cells to prevent cell attachment and agglomeration, before re-establishing normal cell function. In this work, a speckled coating method using a known polycation [poly(l-lysine), PLL] is described to induce cell surface electrostatic charges on three different cell types, namely, two bone cancer cell lines and fibroblasts. The morphology of the PLL speckled coating on the cell surface, internalization and metabolization of the polymer, and prevention of cellular aggregations are reported. Polymer concentration was found to be the key parameter controlling both capsule morphology and cell health. This approach allows a temporary cell coating over the course of 1–2 h, with cells exhibiting phenotypically normal behavior after ingesting and metabolizing the polymer. The process offers a fast and efficient alternative to aid single-cell manipulation for bioprocessing applications. Preliminary work on the application of PLL speckled cell coating in enabling reliable bioprinting is also presented.

Coatings on mammalian cells: interfacing cells with their environment

“…For cell modification, the negative charge on peripheral membranes serves as a convenient electrostatic binding sites for positively charged polymers, polycations, and nanoparticles. Studies have explored many different polycations to modify mammalian cells including poly-L-lysine (PLL) [105], polyallylamine hydrochloride (PAH) [106, 107], and PEI [79].…”

“…One approach was to replace the slight negative charge on the cells with a high density of positive charges for enhanced cell-cell repulsion. By incubating cells in PLL, the polycation species electrostatically adsorbs to the cell surfaces in a speckled cell coating [105]. Since these coatings only partially covered the cell’s surface area, the cells were able to internalize the polymer within a few days and return to normal function.…”

“…Additionally, minimal cell aggregation was observed in coated cells while uncoated cells formed aggregates. Ribeiro et al demonstrate coating cells from two bone cancer cell lines and a fibroblast line [105], while other groups have reported electrostatic anchoring of polymers to K562 cells [107] and macrophages [58]. Due to all mammalian cells having a negative charge, electrostatic coupling can be generalized to many cell populations.…”

“…Specific polycations also have their own drawbacks, as well. PEI is not degradable and prevents cell growth and division [79], and PLL permeabilizes cells through the formation of polycation pores [105].

Fig.

…”

Single‐Cell Nanometric Coating Towards Whole‐Cell‐Based Biodevices and Biosensors

“…To this end, Ferreira and coworkers developed an efficient and temporary single‐cell PLL (poly(L‐lysine)) speckled coating process, with cells exhibiting phenotypically normal behavior after ingesting and metabolizing the polymer. This method allows the cells can be temporarily coated for 1–2 hours, thus succeeded in avoiding them to aggregate, which enabled reliable bioprinting . Although this method is one‐step with its own virtues, the coating was not stable for long time and the coating was not uniform, which would be not good enough for the fabrication of biodevices.…”