Purasorb pdlg 5002

Capped
poly (d,l-lactide-co-glycolide)
with a co-monomer
ratio of 50:50, PURASORB PDLG 5002 (PLGA), was obtained from Corbion
PURAC (NL). Caffeic acid (CA), resveratrol (RV), hydrogen peroxide
(H₂O₂), ascorbic acid (AA), 2,2′-diphenyl-1-picrylhydrazyl
radical (DPPH), poly(vinyl pyrrolidone) K30 (PVP), silver nitrate
(AgNO₃), and nitric acid (HNO₃) were purchased
from Sigma-Aldrich (I); fluvastatin sodium salt (FLV) was a gift from
Novartis (I). DiIC18(5)-DS (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindodicarbocyanine-5,5′-disulfonic
acid) (DIL) was purchased from Thermo Fisher (I). All solvents were
of analytical grade, unless specified.

In our work, polylactic-co-glycolic acids (PLGA) Purasorb PDLG5002 and PDLG7502 (Corbion Purac, Amsterdam, The Netherlands) with an inherent viscosity midpoint of 0.2 dL/g and a lactic-to-glycolic-acid monomer ratio of 50:50 and 75:25, respectively, were used as a raw polymeric material. Both copolymers are supplied in the form of white to light tan-colored granules (1–3 mm across) and are primarily used in biomedical and drug delivery applications [32 ].
Prior to the experiments, initial PLGA granules were thoroughly grinded by a rotary cryomill Model LZM-1M (OLIS, Moscow, Russia) together with solid carbon dioxide (as a cooling agent). The ground polymer powders were then sifted through the Model CB-04 (Vibrotekhnika, St. Petersburg, Russia) calibrated sieve set 50 μm × 50 μm and 100 μm × 100 μm in mesh size to produce a 50–100 μm polymer particle fraction for further use.
The initial levofloxacin substance (CAS Number: 138199-71-0; Sigma-Aldrich, St. Louis, MO, USA) (Figure 1, left) was presented as a fine powder with a mean particle size of ca. 5 to 100 μm (Figure 1, right).
Chemically pure carbon dioxide (99.98%, NIIKM Ltd., Moscow, Russia) and trifluoromethane (99.8%, Rushimprom Corp., Moscow, Russia) were used as PLGA plasticizing and foaming agents without any additional purification.

The production of the microcarriers was extensively described in Muoio et al. [19 (link)]. Briefly, the manufacturing process relies on a double emulsion solvent evaporation technique where the most critical components for the manufacture are 17 KDa Poly(D, L-lactide-co-glycolide) (PLGA) (lactide/glycolide ratio 50:50), Purasorb PDLG 5002 purchased from Corbion Purac (Amsterdam, Netherlands). Polyvinyl alcohol (PVA, 87–89% hydrolyzed, Mw 31 KDa) and methylene chloride from Merck (Darmstadt, Germany). Finally, porcine gelatin, a generous gift from Italgelatine (Santa Vittoria d’Alba, Italy), and ammonium hydrogen carbonate from Applichem (Darmstadt, Germany).