Glycopeptoid nanospheres: glycosylation-induced coacervation of poly(sarcosine)

Conjugation of maltopentaose to water-soluble homo-poly(sarcosine) induced self-association and formed nanospheres (−150 nm) in water although homo-poly(sarcosine) was water-soluble and did not form any aggregates. Fluorescent probe experiments showed that the spheres were non-ionic glycopeptoid coacervate-like particles with both hydrophobic and hydrophilic domains inside.

Okenshoji Co., Ltd. Japan). Excess sample was removed with filter paper. The sample on the grid was instantly freezed by some liquid propane (-196 °C) with Reichert KF80 (Leica, Japan). The freezed grid was placed in a JEM-2100F(G5) (JEOL, Japan) transmittance electron microscope operated at 200kV.

Synthesis
All starting materials and solvents were used without further purification (Scheme S1). Nuclear magnetic resonance spectra were run in methanol-d 4 with a Bruker Avance III 400MHz spectrometer to acquire 1 H-NMR spectra. Chemical shifts (δ) are expressed in parts per million and are reported relative to the solvent peak as an internal standard in 1 H-NMR spectra. Mass spectra were recorded with a Thermo Exactive spectrometer. The molecular weight distribution (MWD) curves, numberaverage molecular weights (M n ), and polydispersity indices (Đ M ) were measured by SEC in DMF containing 10 mM LiBr at 40 °C (flow rate = 0.50 mL min -1 ) with three linear-type polystyrene gel columns (TOSOH TSKgel SuperHM-M; exclusion limit: 4 × 10 6 g mol -1 ; particle size: 3 μm; pore size: N/A; 6.0 mm i.d. × 15 cm) and an HLC-8320GPC (TOSOH) instrument equipped with refractive index and UV-visible detectors ( = 254 nm). The columns were calibrated against 12 poly(methyl methacrylate) standards [PSS: M p =8.00×10 2 to 2.20×10 6 g mol -1 ; Đ M (SEC) = 1.04-1.22].

Compound [4]: N-(methoxycarbonyl)-N-methylglycine
Sarcosine (30.0 g, 337 mmol) was dissolved in 337 mL of 1 M aqueous NaOH and methyl chloroformate (33.9 mL, 438 mmol) was dropwised under cooling with a 0 ºC ice bath. The mixture was stirred for 6 h at room temperature. Then the pH of the solution was adjusted from 11 to 6 with 2 N aqueous HCl. The compound was extracted by diethyl ether. The solvent was removed under reduced pressure.

Compound [5]: sarcosine-N-carboxyanhydride (NCA)
Compound [4] (5.00 g, 34.0 mmol) was dissolved in SOCl 2 (50 mL, 0.693 mol) and the solution was stirred for 12 min in an oil bath at 70 °C. The solution was reprecipitated by pouring into petroleum ether. The crystals were gathered by filtration and dried in vacuo. The dried crystals were dissolved into dry ethyl acetate at 50 °C and the solution was passed via activated carbon. The solvent was removed under reduced pressure at room temperature.

Polymer [2]: Maltotriose-b-poly(N-n-propylglycine)
Compound           Figure S6. Dynamic light scattering profiles of the self-assembly with different temperatures in water.
The glycopeptoid solution was sonicated for 1 min by the bath type sonicator (40kHz, 130W) at 20 °C and the DLS measurements were performed at 20 °C.