# Crosslinked Bifunctional Particles for the Removal of Bilirubin in Hyperbilirubin Cases
## 3 Results  
### St-DVB Functionalized Particle Synthesis  
Various types of particles were synthesized using St and DVB as base materials and functionalized with PEGMA and/or GMA. The reaction yields for these particles ranged between 60.8 and 96.5, as shown in Table 2. The table also includes their median diameter in volume (Dpv 0.5), the Span, and the estimated pressure drops (\(\Delta\)P) calculated using the Ergun equation [18].  
The experimental results indicate that the addition of PEGMA and/or GMA to St-DVB results in a reduction in particle size, with Dpv 0.5 values that are 11.5%, 53%, and 42% smaller for St-DVB-PEGMA, St-DVB-GMA, and St-DVB-GMA-PEGMA, respectively. These findings suggest that functionalization with GMA has a significant effect on particle size reduction. Previous studies have also reported that the use of GMA and PEGMA can reduce particle size [19; 20]. However, in the case of St-DVB particles, the effect of GMA on particle size reduction is more pronounced. Despite the differences in particle size, all the synthesized particles are in the size range potentially suitable for use in hemodialysis carrtridges [21]. In addition, the estimated pressure drops using the Ergun equation are within the limits for extracorporeal systems to prevent blood coagulation, for which maximum admissible pressure drop is 200 mmHg [22].  
FT-IR spectroscopy was used to chemically characterize both functionalized and non-functionalized particles, as shown in Figure 1. A common adsorption band was observed at 3020 cm\({}^{-1}\), which was attributed to the aromatic C-H stretching vibration. Moreover, peaks in the range of 1600-1440 cm\({}^{-1}\) were observed, which corresponded to the C=C phenyl stretching. The bands at 750 and 695 cm\({}^{-1}\) were also observed, which corresponded to the aromatic C-H bending of benzene derivative from polystyrene and polydivinylbenzene, as previously reported [23; 24].  
The functionalization of the particles with epoxide group could not be demonstrated by FT-IR spectroscopy due to the overlay of the epoxide group with the characteristic peaks of the polymer. Thus, the epoxide content of the particles functionalized with GMA was determined, with values of 19 \(\upmu\)mol/g particle for GMA-only functionalized particles and 10 \(\upmu\)mol/g particle in the case of GMA and PEGMA functionalization.  
SEM analysis was conducted to examine the morphology of the synthesized particles, as shown in Figure 2. In the case of St-DVB-PEGMA, the use of SDS resulted in smaller  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Polymer** & **D\({}_{\mathbf{PV\,0.5}}\) (um)** & **Span** & **\(\Delta\)P (mmHg)** & **Yield (\%)** \\ \hline St-DVB & 868 & 1.1 & 2 & 96.5 \\ St-DVB-PEGMA & 769 & 0.9 & 4 & 60.8 \\ St-DVB-GMA & 460 & 1.0 & 9 & 87.3 \\ St-DVB-GMA-PEGMA & 505 & 1.2 & 7 & 87 \\ \hline \end{tabular}
\end{table}
Table 2: Median diameter in volume, Span, estimated pressure drops and yield.  
particles that formed irregularly shaped agglomerates. Although these particles were smaller than St-DVB-GMA and St-DVB-GMA-PEGMA, individual particle size could not be measured by LALLS analysis due to the agglomerate formation. On the other hand, particles synthesized with PVP had a predominantly spherical morphology.