Zetasizer lab

For NTA analysis, isolated exosomes were diluted at the ratio of 1:100, 1:200, or 1:400 in PBS. The size distribution and concentration of isolated exosomes were carried out via NTA using a Nanosight NS300 (Malvern Instruments, UK); the camera level was set at 9 and the detection threshold at 11. Filtered PBS without NPs was used as the background. Three video recordings with duration per 60 s were taken.
Surface charges were assessed by zeta potential measurements, acquired using a Zetasizer Lab (Malvern Instruments, UK). Before the measurements, exosomes isolated by UC and TEI (the pellets after centrifugation) were added to 1 ml of distilled water, while exosomes isolated by DTS chip, PLL‐MNPs, PEI‐MNPs, and LF‐bis‐MPA‐MNPs in 200 μl of elution buffer were completed to 1 ml by adding 800 μl of distilled water. All EV samples from different isolation methods were diluted in distilled water (pH 7.0).

The size and morphology of UPS were assessed using a high-resolution transmission electron microscope (HT7800, Hitachi). The hydrodynamic size and zeta potential of USPIO-PEG and UPS were analyzed using a specialized nanoparticle size and zeta potential analyzer (Zetasizer Lab, Malvern Panalytical Ltd., UK). The magnetic properties of UPS were precisely determined using a Vibrating Sample Magnetometer (VSM) (Model 7404, LakeShore Corporation, USA).
The near-infrared absorption spectra of UPS at different concentrations (25 μg mL⁻¹, 50 μg mL⁻¹, 100 μg mL⁻¹, and 200 μg mL⁻¹) were measured using the ultraviolet spectrophotometry. The near-infrared absorption spectra of UPS were measured using the ultraviolet spectrophotometry both without laser irradiation and after 10 minutes of irradiation with the 808nm near-infrared laser (2.1 W cm⁻²). The characterization works, including high-resolution transmission electron microscopy, hydrodynamic size, zeta potential, and VSM measurements, were meticulously conducted by Nanjing Nanoeast Biotech Co., Ltd., ensuring the accuracy and reliability of the results.