Lignin nanoparticle as a vehicle to load, release, and improve the stability and antioxidant activity of curcumin: Comparison between dropping and pouring regimes

Curcumin (Cur) was loaded in lignin nanoparticles (LNP) via an antisolvent method by pouring (P-) and dropping (D-) regimes, respectively, and Cur-loaded LNP (Cur/LNP) were comparatively characterized. The results indicated that P-Cur/LNP (62–92 nm) was much smaller than D-Cur/LNP (134–139 nm). For both regimes, their maximum loading efficiencies were comparable (91 ± 3%), while dropping regime (236.2 mg/g) demonstrated a higher loading capacity than pouring regime (174.6 mg/g). In both regimes, Cur was loaded in an amorphous form via the hydrophobic, hydrogen-bonding, and π-π interactions with lignin matrix and it demonstrated a controlled release in in vitro digestion test. In comparison, Cur in D-Cur/LNP showed higher stabilities against photodegradation, thermal treatment, and 30-d storage than that in P-Cur/LNP, while P-Cur/LNP concluded a higher antioxidant activity than D-Cur/LNP. The present findings attested that LNP was a valuable tool to stabilize and controlled release of lipophilic phytochemicals as well as improve their bioactivities. [Display omitted] •Curcumin was loaded into lignin nanoparticles (LNP) by two antisolvent methods.•The dropping regime could load more curcumin into LNP than the pouring regime.•Curcumin-loaded LNP exhibited enhanced photochemical, thermal, and storage stability.•LNP and curcumin showed synergetic antioxidant activity in composite nanoparticles.•Curcumin-loaded LNP presented a slow and sustained release profile.