Branson 1800

The microparticles were blended with hexane for 1 min and ultrasonicated for 20 min using an ultrasound bath, Branson 1800 (Branson Ultrasonics Corporation, Danbury, CT, USA) to extract carotenoids. Absorbances of extracts were measured at 450 nm wavelength and recorded using a UV–visible spectrophotometer (Thermo Scientific, Waltham, MA, USA, Genesys 10S). The β-carotene standard was used for quantification, and the results were expressed as µg β-carotene/g sample [27 ]. The test was conducted in triplicate.
The retention after encapsulation was calculated as a ratio of the total carotenoid amount in the microparticles to that in the feed materials before atomization.

TEM imaging of CNTs was performed using an FEI Titan Themis scanning TEM (STEM) operating at 80 kV. The images were acquired in an energy-filtered TEM mode at the zero loss energy. To prepare CNTs, we separated them from the Si substrates and dispersed them in ethanol (90% v/v in water) by bath sonication for 10 min (Branson 1800, Branson Ultrasonics, USA). Then, a drop was placed on a Cu TEM grid coated with a lacey carbon film and allowed to dry before imaging.