2.2.7 Stability (enzymatic, pH 5 and PBS)
To study stability of our gelatin hydrogel containing
PDA-PAR30 NPs (Gel-PDA-PAR30 1:1)
non-dilute we used three different testing configurations: i) stability
in physiological pH, ii) in acidic condition and iii) in the presence of
enzyme (collagenase).
For the experiment at physiological pH, we used PBS solution. Hydrogel
samples were placed in 24 wells-plate with 1 mL of PBS 1X from Dutscher,
at +37°C. Measurements were carried out after vacuum-drying step for 4
hours then we weighed samples. Finally, we put them in a new PBS
solution and put them back at +37°C until next measurement. We performed
these measurements at different time point: initial measurement (before
stability experiment) then at days 1, 4, 7 and 15.
For the experiment in acidic condition (pH=5), protocol was the same as
the previous one with the same follow-up at different time point. We
used a citrate-phosphate buffer (0.15M, pH = 5).
To test enzymatic stability, we used collagenase (Sigma-Aldrich)
solution at 0.1% w/v. Measurements were performed using the same
protocol but with different time points. Measurements were realized at
t0, 30 minutes, 1 hour and 2 hours. All samples were washed three times
with PBS 1X in order to remove collagenase enzyme, dried with paper and
stock until next day to perform vacuum-drying and weigh. All results
were compared to gelatin hydrogel without NPs condition. All samples
were performed in triplicates.