A Laparoscopically Compatible Rapid-Adhesion Bioadhesive for Asymmetric Adhesion, Non-Pressing Hemostasis, and Seamless Seal

Bioadhesive hydrogels offer unprecedented opportunities in hemostatic agents and tissue sealing; however, the application of existing bioadhesive hydrogels through narrow spaces to achieve strong adhesion in fluid-rich physiological environments is challenged either by undesired indiscriminate adhesion or weak wet tissue adhesion. Here, a laparoscopically compatible asymmetric adhesive hydrogel (aAH) composed of sprayable adhesive hydrogel powders and injectable anti-adhesive glue is proposed for hemostasis and to seal the bloody tissues in a non-pressing way, allowing for preventing postoperative adhesion. The powders can seed on the irregular bloody wound to rapidly absorb interfacial fluid, crosslink, and form an adhesive hydrogel to hemostatic seal (blood clotting time and tissue sealing in 10 s, ≈200 mm Hg of burst pressure in sealed porcine tissues). The aAH can be simply formed by crosslinking the upper powder with injectable glue to prevent postoperative adhesion (adhesive strength as low as 1 kPa). The aAH outperforms commercial hemostatic agents and sealants in the sealing of bleeding organs in live rats, demonstrating superior anti-adhesive efficiency. Further, the hemostatic seamless sealing by aAH succeeds in shortening the time of warm ischemia, decreasing the blood loss, and reducing the possibility of rebleeding in the porcine laparoscopic partial nephrectomy model.

Injectable Bioadhesive Hydrogels Scavenging ROS and Restoring Mucosal Barrier for Enhanced Ulcerative Colitis Therapy

Despite the progress in the therapy of ulcerative colitis (UC), long-lasting UC remission can hardly be achieved in the majority of UC patients. The key pathological characteristics of UC include an impaired mucosal barrier and local inflammatory infiltration. Thus, a two-pronged approach aiming at repairing damaged mucosal barrier and scavenging inflammatory mediators simultaneously might hold great potential for long-term remission of UC. A rectal formulation can directly offer preferential and effective drug delivery to inflamed colon. However, regular intestinal peristalsis and frequent diarrhea in UC might cause transient drug retention. Therefore, a bioadhesive hydrogel with strong interaction with intestinal mucosa might be preferable for rectal administration to prolong drug retention. Here, we designed a bioadhesive hydrogel formed by the cross-linking of sulfhydryl chondroitin sulfate and polydopamine (CS-PDA). The presence of PDA would ensure the mucosa-adhesive behavior, and the addition of CS in the hydrogel network was expected to achieve the restoration of the intestinal epithelial barrier. To scavenge the key player (excessive reactive oxygen species, ROS) in inflamed colon, sodium ferulic (SF), a potent ROS inhibitor, was incorporated into the CS-PDA hydrogel. After rectal administration, the SF-loaded CS-PDA hydrogel could adhere to the colonic mucosa to allow prolonged drug retention. Subsequently, sustained SF release could be achieved to persistently scavenge ROS in inflammatory areas. Meanwhile, the presence of CS would promote the restoration of the mucosal barrier. Ultimately, scavenging ROS and restoring the mucosal barrier could be simultaneously achieved via this SF-loaded bioadhesive hydrogel scaffold. Our two-pronged approach might provide new insight for effective UC treatment.

Thermosensitive Bioadhesive Hydrogels Based on Poly(N-isopropylacrilamide) and Poly(methyl vinyl ether-alt-maleic anhydride) for the Controlled Release of Metronidazole in the Vaginal Environment

The development of thermosensitive bioadhesive hydrogels as multifunctional platforms for the controlled delivery of microbicides is a valuable contribution for the in situ treatment of vagina infections. In this work, novel semi-interpenetrating network (s-IPN) hydrogels were prepared by the entrapment of linear poly(methyl vinyl ether-alt-maleic anhydride) (PVME-MA) chains within crosslinked 3D structures of poly(N-isopropylacrylamide) (PNIPAAm). The multifunctional platforms were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermal techniques, rheological analysis, swelling kinetic measurements, and bioadhesion tests on porcine skin. The hydrogels exhibited an interconnected porous structure with defined boundaries. An elastic, solid-like behavior was predominant in all formulations. The swelling kinetics were strongly dependent on temperature (25 °C and 37 °C) and pH (7.4 and 4.5) conditions. The s-IPN with the highest content of PVME-MA displayed a significantly higher detachment force (0.413 ± 0.014 N) than the rest of the systems. The metronidazole loading in the s-IPN improved its bioadhesiveness. In vitro experiments showed a sustained release of the antibiotic molecules from the s-IPN up to 48 h (94%) in a medium simulating vaginal fluid, at 37 °C. The thermosensitive and bioadhesive PNIPAAm/PVME-MA systems showed a promising performance for the controlled release of metronidazole in the vaginal environment.

Dual Regulations of Thermosensitive Heparin-Poloxamer Hydrogel Using ε-Polylysine: Bioadhesivity and Controlled KGF Release for Enhancing Wound Healing of Endometrial Injury

Hydrogel was not only used as an effective support matrix to prevent intrauterine adhesion after endometrial injury but also served as scaffold to sustain release of some therapeutics, especially growth factor. However, because of the rapid turnover of the endometrial mucus, the poor retention and bad absorption of therapeutic agents in damaged endometrial cavity were two important factors hindering their pharmacologic effect. Herein, a mucoadhesive hydrogel was described by using heparin-modified poloxamer (HP) as the matrix material and ε-polylysine (EPL) as functional excipient. Various EPL-HP hydrogels formulations are screened by rheological evaluation and mucoadhesion studies. It was found that the rheological and mucoadhesive properties of EPL-HP hydrogels were easily controlled by changing the amount of EPL in formulation. The storage modulus of EPL-HP hydrogel with 90 μg/mL of EPL (EPL-HP-90) was elevated to be 1.9 × 10⁵ Pa, in accordance with the adhesion force rising to 3.18 N (10-fold higher than HP hydrogels). Moreover, in vitro release of model drug keratinocyte growth factor (KGF) from EPL-HP hydrogel was significantly accelerated by adding EPL in comparison with HP hydrogel. Both strong mucoadhesive ability and the accelerated drug release behavior for EPL-HP-90 made more of the encapsulated KGF absorbed by the uterus basal layer and endometrial glands after 8 h of administration in uterus cavity. Meanwhile, the morphology of endometrium in the injured uterus was repaired well after 3 d of treatment with KGF-EPL-HP-90 hydrogels. Compared with KGF-HP group, not only proliferation of endometrial epithelial cell and glands but also angiogenesis in the regenerated endometrium was obviously enhanced after treatment with KGF-EPL-HP-90 hydrogels. Alternatively, the cellular apoptosis in the damaged endometrium was significantly inhibited after treatment with KGF-EPL-HP-90 hydrogels. Overall, the mucoadhesive EPL-HP hydrogel with a suitable KGF release profile may be a more promising approach than HP hydrogel alone to repair the injured endometrium.