QCM study was carried out with 0.198-cm2 standard-finished 9-MHz AT cut gold resonators (Princeton Applied Research Inc., Oak Ridge, TN, USA) sputtered on quartz. All the experiments were conducted by dipping the quartz crystal into 4 mL of experimental solutions in a 16-well plate at 23 °C. The quartz crystal was dipped into a sequence of reagents, which is described in Section 2.2 for Groups 1–4. Distilled water (pH = 7.0) was used to remove the unstable reagent from the quartz crystal surface. The real-time frequency changes during the experiment were recorded using WinQCM computer software (Princeton Applied Research Inc., Oak Ridge, TN, USA). The surface density of the quartz crystal was calculated.