Long‐acting release of small molecules achieved by barrier effect of nano‐brick

Abstract The long‐acting sustained‐release of active molecules is of great importance in chemical production, food preservative, drug delivery in vivo, and so on. However, the problems of initial‐burst release and short release time (dominated by Fick's lows) commonly exist in sustained‐release materials. Herein, we designed and fabricated two types of film materials to achieve slow, continuous, and long‐term release of small molecules using methyl orange (MO) as a target release substance. B‐MO@polymer films were obtained by embedding MO into polylactic acid/polyethylene glycol (PLA/PEG) substrate and then assembling a layered double hydroxide (LDH)/carboxymethyl chitosan (CMC) barrier layer on the substrate surface. Another type of film (LDH&MO@polymer) was prepared by blending LDH and MO into the PLA/PEG polymer matrix. These films show high loading capacities of ~500 μg/cm 2 for MO and display long‐acting sustained‐release property arising from the barrier effect of LDH nano‐brick. Specifically, for the B‐MO@polymer film, the release time of 50% MO is 10 days and the release time of 80% MO can be extended to 30 days. Ultimately, the time for complete release (>96%) reaches over 60 days. By using LDH‐embedded polymer as carriers for active molecules, the zero‐order release of MO was realized for LDH&MO@polymer films, achieving sustained release within as long as 145 days. This work provides a new paradigm to achieve the long‐acting sustained‐release of active molecules through the barrier effect of 2D nano‐bricks. Highlight Two types of films were obtained to achieve long‐term release of small molecules. The films show high loading capacities for active molecules. The long‐acting property is derived from the barrier effect of 2D nano‐brick. The films can be produced in a large scale and have good application prospects.