Perforated lacy carbon 300 mesh

For cryo‐TEM, 4 µL of the vesicle suspension was applied to a copper grid coated with a perforated lacy carbon 300 mesh (Ted Pella Inc) and blotted with filter paper to form a thin liquid film of solution. The blotted sample was immediately plunged into liquid ethane at its freezing point (−183°C) in an automatic plunger (Lieca EM GP). The vitrified specimens were transferred into liquid nitrogen for storage. Sample analysis was carried out under a FEI Tecnai 12 G2 TEM, at 120 kV with a Gatan cryo‐holder maintained at −180°C. Images were recorded with the Digital Micrograph software package, at low‐dose conditions, to minimize electron beam radiation damage. The measurements were performed at the Ilse Katz Institute for Nanoscale Science and Technology Ben‐Gurion University of the Negev, Beer Sheva, Israel.

Vitrified specimens were prepared according to a standard procedure [56 (link)]. Briefly, $2.5 \mathsf{\mu }\mathrm{L}$ drops of an NP solution were applied to a copper grid coated with a perforated lacy carbon 300 mesh (Ted Pella Inc., Redding, CA, USA) and blotted with a filter paper to form a thin liquid film. The blotted samples were immediately plunged into liquid ethane at its freezing point ( $-183 °\mathrm{C}$ ) using an automatic plunge freezer (EM GP, Leica Microsystems GmbH,Vienna, Austria) and transferred into liquid nitrogen for storage. The samples were analyzed using an FEI Tecnai 12 G2 TEM at $120 \mathrm{kV}$ with a Gatan cryo-holder, maintained at −180 °C. Images were recorded on a CCD camera (Gatan manufacturer, Pleasanton, CA, USA) at low-dose conditions.

Hydrogels of FD, 25 mol% FD-RGD and FD-RGD, each with overall 5% w/v (corresponding to total molar concentrations of 30, 28 and 22 mM, respectively) were prepared by dissolving in 100 μl NaOH 0.1 mM. Vitrified specimens were prepared on a copper grid coated with a perforated lacy carbon 300 mesh (Ted Pella Inc.). A typically 4 μl from a hydrogel sample was applied to the grid to form a thin film. The samples were immediately plunged into the liquid ethane at its freezing point (−183 °C, Lieca EM GP). The vitrified specimens were transferred into liquid nitrogen for storage. The samples were studied using a FEI Tecnai 12 G2 TEM, at 120 kV with a Gatan cryo-holder maintained at −180 °C, and images were recorded on a slow scan cooled charge-coupled device CCD camera. Images were recorded with the Digital Micrograph software package, at low dose conditions, to minimize electron beam radiation damage.