Mfp 3d sa afm

Collagen gels at a concentration of 2 mg/ml (favorable concentration determined in
microvesicle release experiments) were prepared on ice, with and without RJ exosomes
(2.5 × 10⁹/ml). Fifty microliter gels in a 96 well plate were left to
polymerize for 30 min at 37 °C. Gels were then covered with PBS for 5 h and mildly fixed
by immersion in paraformaldehyde 4% (Sigma, US) for 30 mins. Samples were immediately
washed twice with distilled water and kept at 4 °C until atomic force microscopy (AFM)
experiments (within 24 h). For AFM imaging, gels were physiosorbed onto a clean glass
cover slips and immediately placed under a MFP 3D-SA AFM (Asylum Research, US). Images of
5 × 5 µm and 2 × 2 µm were obtained for both conditions in AC mode, employing TAP300GD-G
cantilevers (k ∼ 40 N/m, ∼300 kHz, BudgetSensors, Bulgaria).
Height and amplitude channel data was recorded and processed with proprietary Asylum
Research AFM software (v16.10.211).

Transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) images were obtained using a JEM-2001F (JEOL, 200 kV primary beam) equipped with a Gatan CCD camera. The morphology of the samples was observed by using S-4800 (Hitachi, accelerating voltage of 25 KV) cold field emission scanning electron microscope (FESEM). The crystal structure of heterostructure was analyzed by D8 Advance X-ray diffraction systems (Bruker, λ = 0.154056 nm). Raman spectra of the samples were tested by an InVia (Renishaw, UK) spectrometer to reflect the composition equipped by a 633 nm laser. The thickness of all samples was also analyzed by MFP-3D-SA AFM (AsylumResearch, USA) using a tapping mode at a scan rate of 1 Hz.