*2.1. Materials*

The polyester polymer was obtained from recycled PET bottles available from a local supplier. The bottles previously contained water. Dichloromethane (molecular weight (Mw) = 84.96 g/mol) was purchased from Chimopar trading SRL. Trifluoroacetic acid (Mw = 114.02 g/mol) was obtained from Fluka Analytical. Silver nitrate, NaOH, d-glucose, and eugenol were purchased from Sigma-Aldrich. All chemicals were of analytical purity and used with no further purification.

#### *2.2. Electrospinning Deposition of PET Nanofibers*

The electrospinning method was used to obtain nanostructured membranes from recycled PET. This method is used to produce membranes made up of a fibrous network with interconnected, overlapping, and randomly distributed fibers. Firstly, the PET bottles were cut into small pieces (about 1 cm2) and then added to a mixture of trifluoroacetic acid and dichloromethane. After the complete dissolution of the polymer, electrospinning was performed using the parameters described in Table 1 and Scheme 1.


**Table 1.** The parameters utilized for electrospinning. PET—polyethylene terephthalate.

**Scheme 1.** Synthesis process for control and silver-loaded polyethylene terephthalate (PET\_X\_ctrl and PET\_X\_NanoAg).

#### *2.3. Silver Nanoparticle (NanoAg) Synthesis*

Silver nanoparticles were prepared by reduction. Briefly, two solutions were obtained: one containing 0.1% silver nitrate (0.1 g of AgNO3 + 99.9 mL of H2O) and one containing the reducing agen<sup>t</sup> (300 mL of H2O + 3 g of NaOH + 1 g of d-glucose + 500 uL of eugenol). Sections of the PET's fibrous networks were placed in the AgNO3 solution and left for 10 min under vigorous stirring; subsequently, they were removed and immersed in the reducing agen<sup>t</sup> solution for an equal amount of time. The obtained samples were washed twice with deionized water and allowed to dry at room temperature. After this, the samples were weighed by comparison with the controls in order to estimate the amount of silver nanoparticles immobilized on the fiber surface. The quantified NanoAg varied between 0.998 mg/cm<sup>2</sup> and 1.003 mg/cm2, with an average of measurement ~1 mg/cm<sup>2</sup> in the case of all samples. Samples coated with silver nanoparticles were noted as PET\_2.5\_NanoAg, PET\_5\_NanoAg, PET\_7.5\_NanoAg, and PET\_10\_NanoAg.
