S1 Electronic Supplementary Information Designing biological fluid inspired molecularly crowded ionic liquid media as sustainable packaging platform for Cytochrome c Kavya Bhakuni, a Meena Bisht, ab Pannuru Venkatesu,* a Dibyendu Mondal* c a Department of Chemistry, University of Delhi, Delhi – 110 007, India. b Departamento de Química, Universidade de Aveiro, Campus Universitário de Santiago 3810−193 Aveiro, Portugal c Centre for Nano & Material Sciences, JAIN (deemed to be University), Jain Global Campus, Bangalore- 562112, India. Experimental details Materials. Cytochrome c from the equine heart (≥95%), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (>98%), hydrogen peroxide solution (H 2 O 2 ) 30% (w/w) in H 2 O, ficoll 70 (F70), absolute ethanol (≥99.8%) were purchased from Sigma-Aldrich. PEG 12 kDa (P12) was purchased from Fluka Analyticals. Highly pure anhydrous sodium phosphate monobasic, sodium phosphate dibasic dehydrate and sucrose (Suc) were purchased from Sisco Research Lab (SRL). Choline dihydrogen phosphate (Cho- Dhp) was purchased from IoliTec. All the solutions were prepared in sodium phosphate buffer solution (10 mM) of pH 7 using deionized water. Designing bio-fluid inspired media. To design molecularly crowded system different amalgamations of model crowding agents (P12, F70, and Suc) with Cho-Dhp were utilized. The bio-fluid inspired media was prepared by using a combination of Cho-Dhp (0.5 g/mL) with one, two and three crowding agents and the total concentration of crowders were 50 mg/mL in phosphate buffer of pH 7. The mixture that was prepared was thoroughly mixed in the vortex. The pH of the final solution obtained was adjusted to pH 7 using 0.1 M NaOH or 0.1 M HCl solutions. Activity measurements. Cyt c exhibits peroxidase activity, which was analyzed using ABTS as a substrate in presence of H 2 O 2 . Cyt c carry out oxidation of ABTS resulting into green colored ABTS + radical, this reaction was initiated by adding H 2 O 2 . The changes in absorption at 420 nm was observed with time for five minutes to monitor the generation of ABTS + . All activity measurements were carried out in solution, Electronic Supplementary Material (ESI) for Chemical Communications. This journal is © The Royal Society of Chemistry 2019