Layer-by-layer assembled highly adhesive microgel films

Water-based adhesives which have strong adhesion and can simplify the adhesion process, endow the adhesives with desired functions are important for various applications. In this work, water-based highly adhesive films with drug delivery ability are fabricated by layer-by-layer (LbL) assembly of chemically cross-linked poly(allylamine hydrochloride)-dextran (PAH-D) microgels and hyaluronic acid (HA). Strong adhesion as high as 6.95 ± 0.92 MPa can be achieved when glass substrates deposited with LbL assembled PAH-D/HA films are slightly pressed together. Confocal laser scanning microscope (CLSM) measurements disclose that the strong adhesion originates from the intermixing of HA with PAH-D microgels at the interface of two contacted PAH-D/HA films. Free-standing PAH-D/HA films are released from substrate under assistance of a sacrificial layer for direct use as adhesives because PAH-D microgels have strong interactions with various surfaces. PAH-D/HA adhesive films can load negatively charged drugs such as ibuprofen based on electrostatic interaction between PAH-D microgels and ibuprofen molecules and release them in physiological conditions. Ibuprofen-loaded PAH-D/HA free-standing films can strongly glue periostea, promising their potential application as bioadhesives capable of accelerating the healing of damaged tissues or organs.