Naproxen sodium salt

Polycaprolactone (PCL, Mn = 80,000 Da), tetraethyl orthosilicate (TEOS,≥ 99.0%), naproxen sodium salt (98–102%), phosphate-buffered saline (PBS), Tween 80, heptane (≥ 99%), Pluronic® P-123 (Mn ≈ 5800 Da), and hydrochloric acid (HCl, 37%) were purchased from Sigma-Aldrich (Madrid, Spain). Thymol (THY, 99%) was purchased from Acros Organics (Geel, Belgium). Dichloromethane (DCM, > 99%) and N,N-dimethylformamide (DMF, > 99%) were purchased from Fisher Scientific (Pittsburg, PA USA). Acetonitrile (≥ 99.9%) and formic acid (98–100%) were purchased from VWR (Barcelona, Spain). Tryptone soy agar (TSA) and tryptone soy broth (TSB) were purchased from Laboratorios Conda-Pronadisa SA (Madrid, Spain) and ammonium fluoride (NH₄F, ≥ 98.0%) was purchased from Fluka (Buchs, Switzerland). All compounds and solvents were used without any purification.

High-molecular-weight poly(vinyl
chloride) (PVC), tris(2-ethylhexyl) phosphate (TOP), tridodecylmethyammonium
chloride (TDMACl), anhydrous tetrahydrofuran (THF), NaNO₂, NaCl, NaBr, NaNO₃, CH₃CO₂Na, NaClO₄, NaSCN, NaHCO₃, Na₂SO₄,
sodium benzoate (NaBenz), ibuprofen sodium salt (NaIB), ketoprofen
sodium (NaKF) and ketoprofen lysine (Lys-KF) salts, and naproxen sodium
salt (NaNS) were purchased from Sigma-Aldrich. Ultrapure water was
used for aqueous solution preparation. All of the other chemicals
were of analytical grade and used without further purification.
All reactions were performed in oven-dried glassware under a slight
positive pressure of nitrogen. ¹H NMR (600 and 300 MHz)
and ¹³C NMR (151 and 75 MHz) spectra were determined on
a 600 MHz Bruker and on a 300 MHz Bruker. Chemical shifts for ¹H NMR were reported in parts per million (ppm), calibrated
to the residual solvent peak set, with coupling constants reported
in Hertz (Hz). The following abbreviations were used for spin multiplicity:
s, singlet; d, doublet; t, triplet; q, quadruplet; m, multiplet. Chemical
shifts for ¹³C NMR spectra were reported in ppm, relative
to the central line of a septet at δ = 39.52 ppm for DMSO-d₆. All solvents and starting materials were
purchased from commercial sources when available (Merck Europe, Fluorochem
U.K.).