Engineering living cells with cucurbit[7]uril-based supramolecular polymer chemistry: from cell surface engineering to manipulation of subcellular organelles

Abstract

Supramolecular polymer chemistry, which closely integrates noncovalent interactions with polymeric structures, is a promising toolbox for living cell engineering. Here, we report our recent progress in exploring the applications of cucurbit[7]uril (CB[7])-based supramolecular polymer chemistry for engineering living cells. First, a modular polymer-analogous approach was established to prepare multifunctional polymers that contain CB[7]-based supramolecular recognition motifs. The supramolecular polymeric systems were successfully applied to cell surface engineering and subcellular organelle manipulation. By anchoring polymers on the cell membranes, cell-cell interactions were established by CB[7]-based host-guest recognition, which further facilitated heterogeneous cell fusion. In addition to cell surface engineering, placing the multifunctional polymers on specific subcellular organelles, including the mitochondria and endoplasmic reticulum, has led to enhanced physical contact between subcellular organelles. It is highly anticipated that the CB[7]-based supramolecular polymer chemistry will provide a new strategy for living cell engineering to advance the development of cell-based therapeutic materials.

Scheme 1. Engineering living cells with cucurbit[7]uril-based supramolecular polymer chemistry.

Fig. 1. The design of the multi-functional polymers toward living cell engineering.

Fig. 2. Polymer-analogous reaction. The synthesis of CB[7]-containing polymer NB₅₀-DSPE-CB[7] is used as an example.

Fig. 3. CLSM images of PC-3 and DC 2.4 cells modified with NB₅₀-DSPE-CB[7] (green) and NB₅₀-DSPE-Ada (red), respectively.

Fig. 4. (a) Schematic illustration of the heterogeneous cell–cell attachment. (b) CLSM images and (c) flow cytometry analysis showing the aggregation of PC-3 and DC 2.4 cells by treating with NB₅₀-DSPE-CB[7] and NB₅₀-DSPE-Ada. (d) The ratio of cell aggregation analyzed by flow cytometry.

Fig. 5. CLSM merged images of heterogeneous cell fusion taken at 0 h and 24 h. PC-3 cells (modified with NB₅₀-DSPE-CB[7], green) and DC 2.4 cells (modified with NB₅₀-DSPE-Ada, red).

Fig. 6. Colocalization images of NB₃₀-ERT-CB[7] and NB₃₀-TPP-Ada with MITO and ER. Pearson's colocalization coefficient (PCC) was used to quantify the degree of colocalization.

Fig. 7. Promoting the contact of MITO and ER. (a) Images of PC-3 cells treated with NB₃₀-ERT-CB[7]-2 and NB₃₀-TPP-Ada-2, followed by Mito-Tracker Green and ER-Tracker Red staining. (b) The line plot graphs indicate the fluorescence intensity profiles of Mito-Tracker Green and ER-Tracker Red along the white dotted lines in the magnified images.

Fig. 8. TEM images of PC-3 cells without (left) or with (right) the treatment of NB₃₀-ERT-CB[7]-2 and NB₃₀-TPP-Ada-2. The red arrows reveal the increased contact between the ER and MITO.