A Modified Polymeric Nano-formulation to Control Binding and Release of Insulin

The study involves evaluation of the binding affinity of insulin to modified-hydrophobic nanoparticles to control its release. A specific peptide called hormone binding peptide (Hbpep) was designed to encompass most of the hydrophobic residues aiming to provide controlled hydrophobic interactions. Polycaprolactone (PCL) polymer was used here to prepare nanoparticles as carriers for insulin molecules. Hbpep ligand was attached covalently to these nanoparticles after embedding enormous carboxyl groups on the nanoparticles surface using conventional bioconjugation chemistry. The thermodynamic of insulin binding with the ligands was studied using isothermal titration calorimetry (ITC). The study further evaluated the adsorption behavior of insulin with the conjugates under various microenvironmental conditions using equilibrium microdialysis, fluorescence spectroscopy and dynamic light scattering. The adsorption process was found to be affected by changing the pH of the medium. The modified nanoparticles showed a controlled insulin binding especially at neutral pH. The energetics of binding was found to be of high affinity type demonstrating a potential for developing a controlled delivery system for insulin.