Tunable backbone-degradable robust tissue adhesives via in situ radical ring-opening polymerization

Abstract

Adhesives with both robust adhesion and tunable degradability are clinically and ecologically vital, but their fabrication remains a formidable challenge. Here we propose an in situ radical ring-opening polymerization (rROP) strategy to design a backbone-degradable robust adhesive (BDRA) in physiological environment. The hydrophobic cyclic ketene acetal and hydrophilic acrylate monomer mixture of the BDRA precursor allows it to effectively wet and penetrate substrates, subsequently forming a deep covalently interpenetrating network with a degradable backbone via redox-initiated in situ rROP. The resulting BDRAs show good adhesion strength on diverse materials and tissues (e.g., wet bone >16 MPa, and porcine skin >150 kPa), higher than that of commercial cyanoacrylate superglue (~4 MPa and 56 kPa). Moreover, the BDRAs have enhanced tunable degradability, mechanical modulus (100 kPa-10 GPa) and setting time (seconds-hours), and have good biocompatibility in vitro and in vivo. This family of BDRAs expands the scope of medical adhesive applications and offers an easy and environmentally friendly approach for engineering.

Degradable Nanohydroxyapatite-Reinforced Superglue for Rapid Bone Fixation and Promoted Osteogenesis

“…35 To satisfy the necessary criteria of robust bone adhesive, we engineered the components of the O-BDSG by optimizing the molar ratio of monomers, concentration of cross-linker, and amount of nHAP (Figure S2). While the mechanical properties improve with an increase in the molar concentration of copolymerized HEMA, which is consistent with our previous work, 24 a feed ratio 1:1 of MDO/HEMA was ultimately selected as a trade-off for degradability. And the final dosage of EDMA and nHAP was set at 2.5 mol % and 1.5 wt %, respectively, to maximize mechanical strength and adhesion strength (Figure 2G and Figure S3).…”

“…The bone-adhesion performance of O-BDSG was quantitatively evaluated on bovine bone at room temperature without removing additional oxygen and external energy input (Figure S7). The adhesion strength of O-BDSG by lap shear test on the relatively dry bovine bone surface was 4.12 MPa, nearly twice that of BDSG (2.89 MPa) and our previous work reported (2.26 MPa, when the feed molar ratio of MDO/HEMA was 1:1), and 1 order of magnitude higher than that of commercially available CA (0.36 MPa) (Figure A). The same trend in adhesion strength was observed in the tensile test (Figure B) and 3-point bending test (Figure C); the adhesion strength of the O-BDSG reached up to 4.09 and 9.79 MPa, respectively.…”

“…Nevertheless, increasing the proportion of copolymerized vinyl monomers to achieve higher adhesion strength in adhesives will negatively affect the degradability, and they are biologically inert. 24 Bone is a high modulus and renewable organic−inorganic biocomposite, in which the backbone-degradable bone collagen matrix enables dynamic bone renewal, while inorganic hydroxyapatite crystals provide high mechanical strength (Figure 1A). 6,25 Nanohydroxyapatite (nHAP), being similar to the inorganic component of bone tissue, is biodegradable and bioactive.…”

“…Our recent study demonstrated that in situ rROP is an effective way to fabricate degradable and robust tissue adhesives. Nevertheless, increasing the proportion of copolymerized vinyl monomers to achieve higher adhesion strength in adhesives will negatively affect the degradability, and they are biologically inert …”

Wetting-enhanced adhesion of photo-polymerized supramolecular adhesives for both smooth and rough surfaces

“…Subsequent in situ curing with a combination of superb interfacial wetting provides a feasible approach to the construction of strong adhesives. [25][26][27] For instance, the commercial Super Glue consists of a series of cyanoacrylate monomers, presenting as liquids with high uidity prior to use. Subsequently, anionic polymerization initiated by water in the environment leads to the formation of strong adhesives with an adhesion strength as high as 10 MPa.…”