DOI: 10.15125/bath-01110
title: Dataset for ''Stable cellulose nanofibril microcapsules from Pickering emulsion templates''

description: We used cationized cellulose nanofibrils (CCNF)-stabilized Pickering emulsions (PE) as templates, and the electrostatic interactions were induced by adding the oxidized cellulose nanofibrils (OCNF) at the oil/water interface to form sustainable microcapsules (MCs). The oppositely charged cellulose nanofibrils enhanced the solidity of interfaces allowing the encapsulation of Nile red (NR) dye in sunflower oil droplets. This dataset provides the raw data of the dye release study from these MCs under different conditions, such as through diffusion, centrifugation and mechanical stirring at various pH environments.
description: Quantification of Nile red (NR) release:
For the dye release study, NR was dissolved in SFO at a weight fraction of 0.00275 wt%. The Pickering emulsions and various microcapsules (1st, 2nd and 3rd MCs) were prepared in a 50 mL centrifuge tube (Falcon). Then, 5 mL of pure sunflower oil (NR-free) was added carefully on the top of the PE and MCs (10 mL) suspension along the tube wall. These were then stored at room temperature, allowing for any NR to diffuse from the PE or MCs phase to the top oil layer. The absorbance of the upper oil layer was measured using a UV-Visible spectrophotometer (Agilent 8453) at 520 nm after 1 and 7 days. The NR released was calculated from the calibration curve, and the percentage of dye release with respect to its initial concentration reported.
Dye release studies were also conducted under different applied force fields, namely centrifugation and mechanical stirring at room temperature. In the case of centrifugation, the above-mentioned PE and MCs (10 mL of sample + 5 mL of dye-free fresh oil) were centrifuged at 8000 rpm for 10 min and then allowed to diffuse for 1 and 7 days before taking the absorbance of the upper oil layer at 520 nm. For mechanical stirring studies, the samples were stirred at 2000 rpm for 10 min using an overhead stirrer (propeller dimension 14.5 mm x 12 mm and Falcon tube internal diameter ~27 mm) and then allowed to diffuse for 1 and 7 days. To separate the oil layer from the blend, a short centrifugation (8000 rpm for 2 min) was done after 1 and 7 days just before the absorbance measurement.
In addition, a dye release study on the most stable MCs (3rd MCs) was done in different pH environments (4.0, 5.0, 6.5 and 8.5). The pH of the as-prepared MCs was ~6.5 (without any adjustment); therefore, the lower and higher pH values were obtained using HCl (0.1 M) and NaOH (0.1 M) solution, respectively.
All dye release experiments were repeated in triplicate and error bars report the standard deviation for each data point.

Surface charge:
The ζ-potential of the OCNF (0.05 wt%), CCNF(0.05 wt%), PE and MCs suspensions was measured using a Zetasizer (Malvern Zetasizer Nano ZSP®, UK). PE/MC samples (100 µL) were diluted using DI water (900 µL) before the measurement. The samples (~850 µL) were injected in the folded capillary electrode cell and equilibrated at 25 oC for 120 s before measuring as an average of 5 from 100 scans each. The ζ-potential was calculated using Henry's law utilizing the Smoluchowski model loaded in the Zetasizer software (Malvern).

Microcapsule diameter:
The diameter of microcapsules was measured from the optical micrograph images using ImageJ software.