We report the thermodynamic analysis of the bindings of poly(amidoamine) (PAMAM-G4) nanoparticles with biogenic polyamines spermine (spm), spermidine (spmd) and synthetic polyamines 3,7,11,15-tetrazaheptadecane·4HCl (BE-333) in aqueous solution at physiological conditions. Multiple spectroscopic methods, thermodynamic parameters and molecular modelling were used to analyse polyamine bindings to PAMAM dendrimers. Thermodynamic parameters ΔS, ΔH and ΔG parameters showed that polyamines bind polymer through H-bonding and van der Waals contacts with biogenic polyamines form more stable conjugates than synthetic polyamines. Modelling showed that polyamines are located at the surface of PAMAM with the free binding energy of -3.56 (spermine), -3.88 (spermidine) and -3.13 kcal/mol (BE-333), indicating spontaneous polyamine-polymer interaction at room temperature.
Keywords: Conjugation; Dendrimer; Modelling; Polyamine; Stability; Thermodynamic.
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