“…There are many different protocols for insulin encapsulation into Chit NPs (Figure 2). Insulin can be pre-dissolved in diluted hydrogen chloride (HCl) solution (Abbad et al, 2015), the pH of this final solution can be adjusted with sodium hydroxide (NaOH) (Hecq et al, 2015;, or insulin can even be directly solubilized into diluted NaOH, or directly into TPP solution (Zhao et al, 2014). Then, the insulin solution is added to the chitosan solution right before or during TPP addition (Ma et al, 2005;Azevedo et al, 2011;Makhlof et al, 2011) or added after TPP addition to chitosan (Ma et al, 2002;Erel et al, 2016).…”