## 3 Results and Discussion
### Influence of Dipole Orientation of ZW on the Interactions with Human Serum Proteins
According to the 2D interactions figures, in the MMP model, the hydrogen bonds formed between the oxygen atom of the phosphate group and Leu481 and Val482, while in the MPC model, hydrogen bonds formed between the O atoms of the phosphate and also the acrylate part (owing to its linear conformation and the availability of O atoms in both sites) and Arg222, Lys 195, and Lys 199. Even though MPC seems to have more and also stronger hydrogen bonds than MMP, which typically leads to a stronger hydrophilicity shell and lower fouling property, it demonstrated higher affinity energy for binding to HSA. This phenomenon can be attributed to additional interactions between MPC and HSA, notably the salt bridge. This interaction is the strongest noncovalent molecular contact between oppositely charged residues that keep the ligand-protein in the closed conformation. In the MPC model, salt bridge interactions arise between the oxygen atom of the phosphate and the positively charged nitrogen of the ammonium group, specifically engaging with the Arg222, Lys195, Lys199, Glu153, and Glu292 amino acids of HSA. It is noteworthy that molecular docking revealed no salt bridge interaction between MMP and HSA. Figure 4: _Cont._  
Figure 4: (a) 2D interaction diagrams, (b) 3D images of docking MMP ligand–proteins interactions, and (c) electrostatic maps of interactions. Figure 5: \(Cont\). This underscores that variations in ligand conformation, driven by dipole orientation, play a pivotal role in determining the interactions between proteins and ligands. Consequently, the MPC model ligand exhibits a greater number of both hydrophobic and hydrophilic interactions when binding to HSA, accounting for its elevated affinity binding energy compared to MMP. These observations align with experimental findings documented in the literature [51]. Table 2 provides a comprehensive overview of the docking results and interactions between HSA, FB, and Tr with both MMP and MPC. It should be mentioned that various optimized conformations of MMP and the MPC have also resulted in different interactions with other proteins (FB and TR), resulting in different hydrophobic and hydrophilic interactions and varying affinity energies, as presented in Table 2.  
Furthermore, we have performed molecular docking on n-butyl-substituted choline phosphate monomer (MBP), reported by [PERSON] et al. [50,51] as a feasible candidate for experimental studies. MBP represents a different dipole orientation compared to MPC, as presented in Figure 6. Additionally, MBP has a n-butyl group rather than the methyl group present in MMP, which can be used to compare the effect of dipole orientation versus hydrophilic group on hemocompatibility. Because of the increased hydrophobicity caused by the n-butyl groups, it is anticipated that MBP would differ from its counterparts in terms of dielectric constant, hydrophilicity/hydrophobicity imbalance, and other properties. However, MBP showed a shrinkage structure at minimized energy, similar to MMP (Figure 6). The docking results showed that the affinity energies of MBP binding to HSA, FB, and Tr were \(-5.6\), \(-4.9\), and \(-4.7\), respectively, which are very similar to those of MMP (Figure 7 and Table 2). Comparing MBP and MPC revealed that MPC had higher binding affinity energy to human serum proteins, indicating that MPC is less hemocom  
Figure 5: (**a**) 2D interaction diagrams, (**b**) 3D images of docking MPC ligand–proteins interactions, and (**c**) electrostatic maps of interactions. patible. Since MBP contains an n-Bu group, its lower affinity energy indicates that the dipole orientation contributes more to fouling resistance and hemocompatibility than the existing hydrophobic groups. Table 2 summarizes the molecular docking computation results, including the affinity energy and different interactions between MBP and human serum proteins.