Polypropylene mesh combined with electrospun poly (L-lactic acid) membrane in situ releasing sirolimus and its anti-adhesion efficiency in rat hernia repair.

This study developed, a novel polypropylene (PP) mesh combined with poly (L-lactic acid) (PLA) electrospun nanofibers loaded sirolimus (SRL). The PP mesh was combined with PLA/SRL (1/0, 1/0.01, 1/0.02; mass ratios) composed electrospun membrane characterized by FTIR spectroscopy, XPS and SEM, and evaluated for cytocompatibility in vitro. In an in vivo study, a total of 84 Sprague-Dawley rats were employed to evaluate the efficacy of the novel composite PP mesh anti-adhesion, mechanical properties and inflammation. As a results, the PLA/SRL membrane could compound with PP mesh stably and load SRL. Although tensile testing showed that the mechanical properties of composite mesh decreased in vivo, the integration strength between the tissue and mesh was still able to counteract intra-abdominal pressure. Compared with the native PP mesh group, the novel PP mesh group showed a lower score for abdominal adhesion and inflammation. More importantly, the novel PP mesh completely integrated with the abdominal wall and had sufficient mechanical strength to repair abdominal wall defects.

Amphiphilic Crosslinked Four-Armed Poly(lactic-co-glycolide) Electrospun Membranes for Enhancing Cell Adhesion.

Common poly(lactide-co-glycolide) (i-PLGA) has emerged as a biodegradable and biocompatible material in tissue engineering. However, the poor hydrophilicity and elasticity of i-PLGA lead to its limited application in tissue engineering. To this end, an amphiphilic crosslinked four-armed poly(lactic-co-glycolide) was prepared. First, four-armed PLGA (4A-PLGA) was synthesized by polymerizing l-lactide (LA) and glycolide (GA) with pentaerythritol as the initiator. Then, the hydrophilic polymer poly(glutamate propylene ester) (PGPE) was prepared through the esterification of glutamic acid and 1,2-propanediol. The hydrophilic 4A-PLGA-PGPE was finally synthesized through the condensation reaction of 4A-PLGA and PGPE with the aid of triphosgene. 4A-PLGA-PGPE was then used to prepare amphiphilic membranes by electrospinning. It was demonstrated that the mechanical properties and biocompatibility of 4A-PLGA were improved after the introduction of PGPE. Furthermore, the introduction of glutamate improved the hydrophilicity of 4A-PLGA, thus effectively promoting cell entry and adhesion, which makes the electrospun 4A-PLGA-PGPE membranes promising for tissue engineering.

Hydrogel adhesive formed via multiple chemical interactions: from persistent wet adhesion to rapid hemostasis.

To date, the robust and durable adhesion capability of hydrogel adhesives in wet environments remains a huge challenge. Herein, a physicochemically double-network crosslinked hydrogel matrix was prepared by mixing acrylic acid (AAc), chitosan (CS) and tannic acid (TA) as the main components and the subsequent in situ polymerization of AAc. The abundant reactive sites on the surface of the hydrogel matrix facilitate rapid, strong and repeatable adhesion to different surfaces of engineering solids and biological tissues in an aquatic environment. The formation of amide covalent bonds resulting from the addition of the bridging agent further expands the long-term application of the hydrogel in tissue repair, and the constructed hydrogel-tissue adhesive interface still has robust adhesion energy after soaking in a physiological environment for up to one month. Moreover, the hydrogel showed fantastic hemostatic performance due to its characteristics of platelet adhesion and high burst pressure. Overall, the persistent adhesion and excellent cytocompatibility of the hydrogel adhesive make it potentially applicable in medical adhesives.

Fabrication of Porous Crystalline PLGA-PEG Induced by Swelling during the Recrystallization Annealing Process.

Poly(lactide-co-glycolide) (PLGA) has been widely used as a scaffold material for tissue engineering owing to its biocompatibility, biodegradability, and biosafety. However, lactic acid (LA) produced during PLGA degradation is prone to inflammation, which is a shortcoming that must be avoided. To this end, crystalline PLGA-PEG was synthesized here for the first time. To make the crystalline PLGA-PEG more suitable for tissue engineering, porous crystalline PLGA-PEG was prepared via the swelling behavior during recrystallization annealing. The structure and properties of the porous crystalline PLGA-PEG were confirmed by SEM, POM, and XRD. Furthermore, the swelling behavior of different PEG molecular weights was studied, and the cell viability test and alkaline phosphatase activity test showed that PLGA-PEG has good biocompatibility. Such a porous crystalline PLGA-PEG will make PLGA have a broader application prospect in bone repair.

High-Strength Hydrogel Adhesive Formed via Multiple Interactions for Persistent Adhesion under Saline.

Hydrogel adhesives have been widely used in wet environments. Nonetheless, strong and stable persistent adhesion remains a challenge. Here, we report a facile yet powerful strategy to construct high-strength hydrogel adhesives for durable adhesion in a saline environment. Such a hydrogel consists of two polymer networks: a hydrophobic-associated polyacrylamide network of covalent and noncovalent cross-links and an alginate network cross-linked by divalent cations in saline. Meanwhile, polydopamine nanoparticles formed through in-situ self-polymerization are distributed evenly throughout the system to provide underwater adhesion. A low and controllable swelling rate and high compressive strength of hydrogels can be achieved via this multiple interaction strategy. Ultimately, this strategy contributes to the persistent underwater adhesion of hydrogels, and the decreasing rate of lap-shear adhesion strength of hydrogels is only 24.79 ± 8.01% after saline immersion for up to 21 days. Moreover, good cytocompatibility of hydrogels is helpful for their application in the biomedical field.

A high-strength double network polydopamine nanocomposite hydrogel for adhesion under seawater.

Mussel-inspired catechol-based strategy has been widely used in the development of underwater adhesives. Nonetheless, the properties of the adhesives were still severely limited under harsh environments. A facile approach was proposed herein to prepare a double network hydrogel adhesive with low swelling rate and high strength in seawater, where the first network was polyacrylamide (PAM) and the second network was alginate (Alg). Meanwhile, polydopamine (PDA) nanoparticles, which were formed through self-polymerization as adhesion anchoring sites, distributed evenly throughout the double network hydrogel and effectively enhanced the adhesion capability of the hydrogel. The properties of the resulting hydrogel have been fully characterized. The optimal adhesion strength of the hydrogel adhesive in seawater was as high as 146.84 ± 7.78 kPa. Furthermore, the hydrogel also has excellent ability to promote the growth of zooxanthellae. Our studies provide useful insights into the rational design of underwater adhesives with high performances even beyond nature.

Self-Assembled Supramolecular Hybrid Hydrogels Based on Host-Guest Interaction: Formation and Application in 3D Cell Culture.

In recent decades, in vitro three-dimensional (3D) cell culture has been rapidly developed and widely used in many biomedical fields. Based on this background, a kind of self-assembled supramolecular hybrid hydrogel materials based on host-guest interaction of ß-cyclodextrin (ßCD) and adamantane (Ad) is designed for 3D cell culture. First, ßCD is grafted to poly(methyl vinyl ether-alt-maleic acid) (PMM) to obtain the host polymers of ßCD-grafted-PMM (PMM-ßCD). Second, the guest polymers of poly(acrylamide-co-N-adamantyl acrylamide) (PAAm-Ad) are synthesized through free-radical copolymerization of acrylamide and N-adamantyl acrylamide. Finally, the self-assembled supramolecular hybrid hydrogels of PMM-ßCD/PAAm-Ad are formed by simply mixing the aqueous solution of host and guest polymers with a total concentration of 3.3% (w/v) and a ßCD/Ad molar ratio of 1:1. The main cross-linking interactions come from the host-guest interaction of ßCD/Ad as well as hydrogen-bonding interaction of carboxyl/amide groups. The prepared hydrogels with good cytocompatibility have been successfully used as 3D cell culture scaffold for SKOV3, HUVEC, and L929 cells culture. Thus, this work provides a way and biomaterial for the preparation of a functionalized 3D cell culture scaffold, which lays an experimental and theoretical basis for cell follow-up research.