Gatan digital imaging system

The hydrodynamic size and zeta potential measurements of the prepared TNPs and DOX-loaded TNPs were analyzed by Dynamic light scattering (DLS) using a Zetasizer Nano ZSP (Malvern, Worcestershire, UK). The Smoluchowski model was used to calculate the zeta potential value. All data represents the average of triplicate measurements of samples prepared in different preparations. The morphology of the prepared TNPs was further analyzed using Transmission Electron Microscope (TEM, Tecnia G2, Spirit Bio TWIN). TEM samples were prepared by drop casting and evaporation technique using formvar coated copper grid (400 mesh). TEM images were analyzed by GATAN digital imaging system (GATAN, Inc.). The amount of encapsulated DOX and the resulting encapsulation efficiency was quantified spectrophotometrically using UV-VIS microplate reader by measuring the absorbance at 490 nm.

Freshly purified exosomes were diluted with DPBS and 4 µL volume was deposited on formvar coated 200 mesh copper grids. After 2 min, grids were blotted dry on Whatman filter paper #1. The grids were inverted over a drop of 2% aqueous uranyl acetate. After 2 min, grids were blotted dry on Whatman filter paper #1, and air dried. All grids were examined under transmission electron microscope, FEI Tecnai G2 Spirit BioTWIN (FEI Company, Hillsboro, Oregon, USA) at an acceleration voltage of 80 kV and digital images were captured with scale bar using a GATAN digital imaging system (Gatan, Inc., CA). Exosome size was measured using GATAN microscopy suite (Gatan, Inc., CA). The diameter of 120 exosomes per sample was manually marked and calculated using “line annotation with length” standard tool of GATAN software. The diameter of UD-P19 and P19N exosomes was analyzed using unpaired two-tailed t-test (GraphPad Prism, version 9.2.0).