Fig. 4: Reaction between surface-thiolated bacteria and mucin.

a Schematic illustration of catalyst-free reaction between thiolated bacteria and mucin via dynamic thiol-disulfide exchange. b MFI values of unmodified EcN and EcN@SH with 8.5 × 10⁷ thiols per cell post reaction with 0.03 mg/ml of Cy5.5_mucin for 1 h. c Flow cytometry histograms and d MFI values of Cy5.5_mucin-attached EcN@SH with different surface thiol densities after reaction with 0.1 mg/ml of Cy5.5_mucin for 1 h. e Flow cytometry histograms and f MFI values of mucin-attached EcN@SH after reaction with Cy5.5-maleimide. g Schematic illustration of blocked thiol-disulfide exchange by reductants. h Flow cytometry histograms and i MFI values of EcN@SH after reaction with 0.03 mg/ml of Cy5.5_mucin in the presence of 0, 0.3, or 1 mg/ml of l-ascorbic acid. j Representative LSCM images of EcN@SH after reaction with Cy5.5_mucin in the presence or absence of 1 mg/ml of l-ascorbic acid. Scale bar: 3 µm. The a.u. indicates arbitrary units. Data are presented as mean values ± SD (n = 3, from independent experiments). Significance was assessed using Student’s t test (two-tailed) or one-way ANOVA analysis followed by Fisher’s LSD multiple comparisons, giving P values, *P < 0.05, **P < 0.01, ****P < 0.0001. Source data and the exact P values are provided in the Source Data file.