Delivery of protein drugs would be an effective approach if mechanistic understanding of protein adsorption at solid/liquid surface is obtained and nonspecific adsorption can be controlled. This study involves evaluation of the thermodynamic parameters for interaction between recombinant human growth hormone (r-hGH) and nanoparticles of poly (lactic- co- glycolic) acid polymer of different molecular weight. Energy changes related to protein-nanoparticle interactions are usually very small and isothermal titration calorimetry (ITC) is the only technique that determines the binding constant (Ka), enthalpy, (ΔH) and stoichiometry, (n) in a single experiment. Therefore, we used ITC to study the energetics of the binding of r-hGH with PLGA nanoparticles. The largely negative ∆H and ∆S suggested that binding was driven by non-classical hydrophobic effect for interaction with PLGA 50501A and PLGA 8515E nanoparticles at pH 7.2 where higher surface coverage was noted for the latter. Endothermic, entropically driven reaction was observed upon interaction of r-hGH with PLGA 5050 5E nanoparticles at pH 7.2, PLGA 5050 1A nanoparticles at pH 5.3 and pH 4.0. Moreover, negative value of ΔCp for PLGA 50501A NPs at pH 7.2 indicated cooperative disorder of hydrogen-bonding networks and no evidence of hydrophobic elements. ITC proved to be very efficient method in studying the thermodynamics of the protein polymer interaction. In agreement with results from previous studies using fluorescence spectroscopy, circular dichroism and dynamic light scattering in our laboratory, this study demonstrated that adsorption can be controlled by selecting the polymer of low to moderate hydrophobicity depending on the pH of media.

如果获得了对固/液表面蛋白质吸附的机械理解并且可以控制非特异性吸附，那么蛋白质药物的输送将是一种有效的方法。该研究涉及对于基因重组人生长激素（R-hGH）的和聚的纳米颗粒之间的相互作用的热力学参数的评价（乳酸-共-不同分子量的乙醇酸聚合物。与蛋白质-纳米颗粒相互作用相关的能量变化通常很小，而等温滴定热量法（ITC）是唯一在单个实验中确定结合常数（Ka），焓（ΔH）和化学计量（n）的技术。因此，我们使用ITC来研究r-hGH与PLGA纳米粒子结合的能量学。∆H和∆S大多为负值，表明结合是由非经典疏水效应驱动的，在pH 7.2下与PLGA 50501A和PLGA 8515E纳米粒子相互作用，后者的表面覆盖率更高。在r-hGH与pH 7.2的PLGA 5050 5E纳米颗粒，pH 5.3和pH 4.0的PLGA 5050 1A纳米颗粒相互作用时，观察到吸热，熵驱动的反应。此外，pH值为7.2时PLGA 50501A NP的ΔCp负值表示氢键网络的协同紊乱，没有疏水元素的迹象。在研究蛋白质聚合物相互作用的热力学时，ITC被证明是一种非常有效的方法。与以前在我们实验室中使用荧光光谱，圆二色性和动态光散射进行的研究结果一致，该研究表明，可以根据介质的pH值选择低至中等疏水性的聚合物来控制吸附。