Popova Tatiana O, Zhulina Ekaterina B, Borisov Oleg V
Center for Chemical Engineering, ITMO University, 197101 St. Petersburg, Russia.
NRC Kurchatov Institute-PNPI-IMC, 199004 St. Petersburg, Russia.
Int J Mol Sci. 2025 Aug 14;26(16):7867. doi: 10.3390/ijms26167867.
The self-consistent field Poisson-Boltzmann framework is applied for analysis of equilibrium partitioning of ampholytic protein-like nanocolloids between buffer solution and weak (pH-sensitive) versus strong polyelectrolyte (polyanionic) brushes with the same net charge per unit area. The position-dependent nanocolloid net charge and the insertion freeenergy profiles are derived as a function of pH and ionic strength in the solution. It is demonstrated that, similar to strong polyelectrolyte brushes, pH-sensitive brushes are capable of the uptake of nanocolloids in the vicinity of the isoelectric point, that is, when the net charge of the colloid in the buffer has either the opposite or the same sign as the ionized monomer units of the brush. At pI≥pKbrush and pH≥pI, the particle absorption patterns by similarly (negatively) charged brushes are qualitatively similar in the cases of strong and weak polyelectrolyte brushes, but the freeenergy barrier at the brush periphery is wider for weak than for strong polyelectrolyte brushes, which may cause stronger kinetic hindrance for the nanocolloid uptake by the brush. A decrease in pH below the IEP leads to a monotonic increase in the depth of the insertion freeenergy minimum inside a strong polyelectrolyte brush, whereas for weak polyelectrolyte brushes, a more peculiar trend is predicted: due to competition between the increasing positive charge of the nanocolloid and the decreasing magnitude of the negative charge of the brush, the absorption is weakened at low pH.
自洽场泊松-玻尔兹曼框架被用于分析两性蛋白质样纳米胶体在缓冲溶液与具有相同单位面积净电荷的弱（pH敏感）和强聚电解质（聚阴离子）刷之间的平衡分配。作为溶液中pH值和离子强度的函数，推导出了位置依赖的纳米胶体净电荷和插入自由能分布。结果表明，与强聚电解质刷类似，pH敏感刷在等电点附近能够摄取纳米胶体，也就是说，当缓冲液中胶体的净电荷与刷的离子化单体单元具有相反或相同的符号时。在pI≥pKbrush且pH≥pI时，对于带相同（负）电荷的刷，强聚电解质刷和弱聚电解质刷的颗粒吸收模式在定性上相似，但弱聚电解质刷在刷周边的自由能垒比强聚电解质刷更宽，这可能会导致纳米胶体被刷摄取时产生更强的动力学阻碍。pH值降至等电点以下会导致强聚电解质刷内部插入自由能最小值的深度单调增加，而对于弱聚电解质刷，则预测会出现更奇特的趋势：由于纳米胶体正电荷增加与刷负电荷减少幅度之间的竞争，在低pH值下吸收会减弱。
