## 2 Materials and Methods
### Synthesis of the Photoactive Microparticles  
The polymeric photosensizers employed in this study are derived from a method initially presented by [PERSON] where Rose Bengal was covalently attached to chloromethylated styrene resins [61]. The hydrophilic properties of the synthesized materials are imparted through the incorporation of two hydrophilic functional groups--ethylenediamine and \(\gamma\)-gluconolactone--into the polymer matrix, following the approach outlined by [PERSON] [62]. The experimental process for synthesizing the polymers is described below. The synthesis of polymer P1 was conducted via a thermally initiated radical polymerization reaction. In a beaker, 100 mg of AIBN (1% by weight relative to the total weight) was dissolved along with a mixture of 6.67 g of divinylbenzene (DVB, isomer mixture, 80% grade) and 3.33 g of p-chloromethylstyrene (CME, 90% grade), maintaining a DVB/CME weight ratio of 2:1. The porogenic mixture, consisting of 12.50 g of 1-dodecanol (125% by weight of the polymerization mixture) and 2.50 g of toluene (25%), was then added to achieve a polymeric mixture/porogenic mixture ratio of 1:2. The resulting solution was homogenized and transferred into a glass tube, which was purged with nitrogen gas for 5 min. The tube was then sealed and placed in a silicone oil bath at 80 \({}^{\circ}\)C for 24 h, allowing the polymerization to proceed quantitatively. After this period, the system was cooled to room temperature, and the polymer was mechanically extracted from the mold. The resulting monolith was manually fragmented and placed into a cellulose extraction tube. It was washed with THF for 24 h at 85 \({}^{\circ}\)C using Soxhlet distillation to remove the porogenic mixture and any unreacted monomers or oligomers. Finally, the polymer was dried in a vacuum oven at 60 \({}^{\circ}\)C and ground into a fine white powder. The second reaction step involved anchoring Rose Bengal onto the polymeric matrices obtained in the first step (P1). In a 500 mL two-neck round-bottom flask, 11.54 g of P1 (15 mmol of -CH\({}_{2}\)Cl) and 17.62 g of Rose Bengal (17.32 mmol) were weighed. Subsequently, 400 mL of dry DMF was added, and the mixture was purged with nitrogen for 30 min. The reaction was conducted under reflux with stirring at 80 \({}^{\circ}\)C for 8 h. After cooling to room temperature, the solid polymer was filtered and sequentially washed with 200 mL portions of ethyl acetate, ethanol, 1:1 water/ethanol, water, 1:1 water/methanol, and methanol. Finally, the polymer was dried in a vacuum oven at 55 \({}^{\circ}\)C, yielding light pink polymeric particles. The process is shown in Figure 1.  
To obtain polymer P3, P2 was reacted with ethylenediamine via a nucleophilic substitution S\({}_{\text{N}}\)2 reaction [62], such that the ethylenediamine interacted with the chloromethyl1 groups that had not reacted in the previous step. A total of 9.33 g of P2 and 15 mL of ethylenediamine (in excess) were placed into a 250 mL two-neck round-bottom flask. The mixture was dispersed in 100 mL of dry THF, sealed, and purged with nitrogen for 30 min. The reaction mixture was then maintained under reflux at 70 \({}^{\circ}\)C for 8 h. After cooling to room temperature, the solid was filtered and washed sequentially with 200 mL portions of THF, dioxane, 1:1 dioxane/water, water, 1:1 dioxane/water, dioxane, and ethanol. Finally,the polymer was dried in a vacuum oven at 55 \({}^{\circ}\)C, yielding polymeric particles with a brighter pink color compared to P2. Finally, to obtain the P4 polymer, a final reaction step was performed, involving the addition of \(\gamma\)-gluconolactone to the amine groups of the P3. In a 250 mL two-neck round-bottom flask, 5.74 g of P3 and 1.335 g of \(\gamma\)-gluconolactone (in excess) were introduced. The mixture was dispersed in 100 mL of absolute ethanol and purged with nitrogen for 30 min.