Fig. 3: In situ copolymerization of functional monomers at selected biological sites on living cells for directing longitudinal assembly.

a–d Longitudinal amplification concept. In situ copolymerization of HPMA and AA-PEG₄-azide at selected sites (GalNAc, Met or Cho) to yield P^azide-engineered cells. After each step of (1)~(3), the amount of azide was assessed by dibenzoazacyclooctyne (DBCO)-Cy5 staining. The growth of P^azide achieved efficient longitudinal amplification of the azide metabolically labeled at the selected sites. Scale bar, 8 μm. Zoomed-in images showed a single stained cell. Scale bars, 3 μm. e, f Evaluation of the retention time of polymers grown from different sites. e The metabolically-labeled cells (Cell-azide) or P^azide-grown cells (Cell-P^azide) were staining by DBCO-Cy5, cultured for 24 h, and observed using CLSM. Scale bar, 8 μm. f Fluorescence intensity ratios (retention ratios) of Cell-P^azide (with polymer grown for 1 or 2 min) or Cell-azide after 24 h of incubation versus 0 h of incubation (n = 10 cells per condition). g Stimulated emission depletion (STED) super-resolved images of single Cell-P^azide with polymer grown (1 or 2 min) from selected sites (GalNAc, Met or Cho) (scale bar, 3 μm) and further magnified STED images (scale bar. 1 μm). Azide was stained with Click-iT™ sDIBO. h STED images of cells from (g) after 24 h of culture, scale bar, 3 μm. Data are representative of three independent experiments with similar results.