Cellulose Nanofiber-Coated Perfluoropentane Droplets: Fabrication and Biocompatibility Study

Purpose: To study the effect of cellulose nanofiber (CNF)-shelled perfluoropentane (PFP) droplets on the cell viability of 4T1 breast cancer cells with or without the addition of non-encapsulated paclitaxel. Methods: The CNF-shelled PFP droplets were produced by mixing a CNF suspension and PFP using a homogenizer. The volume size distribution and concentration of CNF-shelled PFP droplets were estimated from images taken with an optical microscope and analyzed using Fiji software and an in-house Matlab script. The thermal stability was qualitatively assessed by comparing the size distribution and concentration of CNF-shelled PFP droplets at room temperature (similar to 22 degrees) and 37 degrees C. The cell viability of 4T1 cells was measured using a 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Additionally, a hemolysis assay was performed to assess blood compatibility of CNF-shelled PFP droplets. Results: The droplet diameter and concentration of CNF-shelled PFP droplets decreased after 48 hours at both room temperature and 37 degrees C. In addition, the decrease in concentration was more significant at 37 degrees C, from 3.50 +/- 0.64x10(6) droplets/mL to 1.94 +/- 0.10x10(6) droplets/mL, than at room temperature, from 3.65 +/- 0.29x10(6) droplets/mL to 2.56 +/- 0.22x10(6) droplets/mL. The 4T1 cell viability decreased with increased exposure time and concentration of paclitaxel, but it was not affected by the presence of CNF-shelled PFP droplets. No hemolysis was observed at any concentration of CNF-shelled PFP droplets. Conclusion: CNF-shelled PFP droplets have the potential to be applied as drug carriers in ultrasound-mediated therapy.