N boc serinol

Trifluoroacetic acid (TFA), 2,2,2-trifluoroethanol (TFE), N-hydroxysuccinimide (NHS), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC), and 1,1,1,3,3,3-hexafluoro-2-propanol (HFP) were purchased from Alfa Aesar (Ward Hill, MA, USA). Anhydrous dichloromethane (DCM) was purchased from JT Baker (Phillipsburg, NJ, USA). The pentapeptide Gly-Arg-Gly-Asp-Ser (GRGDS) was purchased from Biomatik (Wilmington, DE, USA). N,N-dimethylformamide (DMF), hexamethylene diisocyanate (HDI), N-BOC-serinol, urea, and poly(ε-caprolactone) (PCL, M_n: 70,000-90,000 g/mol) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Anhydrous diethyl ether was purchased from Fisher Scientific (Pittsburgh, PA, USA).

Poly(ε-caprolactone) (PCL) diol ( ${\overline{M}}_n$ 2000 g/mol), Poloxamer^® P407 (P407, ${\overline{M}}_n$ 12,600 g/mol, 70% poly(ethylene oxide) (PEO)), 1,6-hexamethylene diisocyanate (HDI), N-Boc-serinol, L-lysine ethyl ester (H-Lys(H)-OEt) dihydrochloride, and dibutyltin dilaurate (DBTDL) were purchased from Sigma Aldrich, Milan, Italy. N-Boc-serinol and l-lysine ethyl ester were used as chain extenders during poly(urethane) (PU) synthesis. Poly(ε-caprolactone) diol and Poloxamer^® P407 were dried under reduced pressure at 100 °C for 8 h and then cooled down at 45 °C under vacuum to remove residual water before use. HDI was distilled under reduced pressure before use. For nanoparticle preparation, curcumin, poly(vinyl alcohol) (PVA), and Tween^® 80 were purchased from Sigma Aldrich, Milan, Italy. All solvents were purchased from Sigma Aldrich, Milan, Italy, in analytical grade. Milli-Q deionized water was produced by a Millipore water purification system (Millipore Corporation, Milan, Italy).

The commercially available triblock co-polymer Poloxamer^® 407 (P407, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), PEO-PPO-PEO, $\overline{M_n}$ = 12,600 Da) was purchased from Sigma Aldrich (Milan, Italy) and used as macrodiol for PEU synthesis after drying at 100 °C for 8 h and cooling at 40 °C under a vacuum (approx. 200 mbar). Furthermore, 1,6-hexamethylene diisocyanate (HDI) and N-Boc serinol were also purchased from Sigma Aldrich (Milan, Italy) and used as a diisocyanate and chain extender during PEU synthesis, respectively. Before use, HDI was distilled under reduced pressure to remove moisture and stabilizers, while N-Boc serinol was stored in a desiccator under a vacuum. The organotin compound dibutyltin dilaurate (DBTDL) was purchased from Sigma Aldrich (Milan, Italy) and added in a catalytic amount to catalyze the PEU synthesis reaction. The synthesis was performed using 1,2-dichloroethane (DCE, Carlo Erba Reagents, Milan, Italy) as a solvent. Before the synthesis procedure, DCE was anhydrified over activated molecular sieves (4 Å, Sigma Aldrich, Milan, Italy, activation at 120 °C overnight) under nitrogen atmosphere overnight. All other solvents required for PEU synthesis were purchased from Carlo Erba Reagents (Milan, Italy) in analytical grade and used as received.