Kinetex 5u c18 100a

Coated meshes (n = 3) were immersed in 3 mL of warmed sterile PBS and incubated at 37 °C for 5 days. At different time-points, 1 mL aliquots were collected for further evaluation and the same volume of warmed PBS was refilled into each sample. Rif release from coated meshes was assessed using high performance liquid chromatography (HPLC, Agilent Technologies 1260 Infinity with a column Phenomenex “Kinetex 5u C18 100A,” Santa Clara, CA, USA). The mobile phase consisted of a mixture milliQ H₂O (with 0.2% Trifluoroacetic acid, TFA) with acetonitrile (both from Carl Roth GmbH, Karlsruhe, Germany), ratio 50/50 at a flow rate of 1 mL/min. The Rif was detected using UV-lamp at 345 nm. Results were expressed as the cumulative percentage release of Rif over time.

The drug loading (DL) calculated as shown in Equation (1) is defined as the mass fraction of a NP that is composed of drug. The entrapment efficiency (EE) (Equation (2)) is defined as the fraction of drug effectively encapsulated into the NPs compared with the amount of drug that was used to prepare the NPs.
$$\mathrm{DL}(\%)=\frac{\left(mgofencapsulateddrug\right)}{\left(mgofpolymer\right)}\times 100$$
$$\mathrm{EE}(\%)=\frac{\left(mgofencapsulateddrug\right)}{\left(mgofdruginitiallyaddedtotheformulation\right)}\times 100$$
The DL was determined by two methods: (i) an indirect method, analyzing the non-incorporated drug in the supernatants after NP centrifugation and (ii) a direct method, dissolving the NPs (pellet) and quantifying the extracted drug. The DLs and EEs calculated through both methods were consistent with less than 5% differences, validating the method.
VCM was quantified by reverse-phase liquid chromatography, using a C18 column (Kinetex 5u C18, 100A, Phenomenex, Le Pecq, France) connected to a HPLC (Agilent 1100, Agilent Technologies, Les Ulis, France) system with a UV-vis detector (wavelength was fixed at λ = 254 nm). The chromatographic conditions are detailed in the Table S1.