A hydrophilic/hydrophobic janus membrane based on directionally frozen polyvinyl alcohol hydrogel for dural defect repair

Background and objectives

Cerebrospinal fluid leakage and postoperative tissue adhesion are serious complications following dural injury. Current dural substitutes often lack the functional asymmetry of the native dura mater. This study aimed to develop a hydrophilic/hydrophobic Janus polyvinyl alcohol (PVA) hydrogel membrane with a directional structure and dual functionality for effective dural defect repair.

Methods

A PVA hydrogel with an aligned porous architecture was fabricated via directional freezing combined with salt leaching, and thermal annealing was applied to enhance mechanical strength and structural stability. The hydrogel was asymmetrically modified to obtain a Janus membrane. Morphology, mechanical properties, degradation, swelling, wettability, in vitro biocompatibility, and cell migration were evaluated by the NIH-3T3 mouse fibroblast cell line. In vivo biocompatibility was assessed using a rat subcutaneous implantation model, including blank control, Durepair®, frozen-salted PVA, and Janus-PVA groups, with 5 rats in each group. Dural repair efficacy was evaluated in a rat cranial dural defect model, including untreated defect control, frozen-salted-annealed PVA, and Janus-PVA groups, with 15 rats in each group.

Results

The Janus membrane exhibited high tensile strength (8.93 ± 1.46 MPa), slow degradation (1.42% mass loss at 28 days), and low swelling (58.13% water content at 28 days). It displayed distinct bilateral wettability, and effectively blocked fibroblast migration on both sides, acting as a physical barrier against fibroblast-driven adhesion. In the rat dural defect model, the Janus membrane reduced cerebrospinal fluid leakage and brain–dura adhesion compared with the untreated defect and frozen-salted-annealed PVA control groups.

Conclusions

In this study, a hydrophilic/hydrophobic Janus membrane was developed via directional freezing, salt leaching, and annealing of a PVA hydrogel for dural repair. The synergistic strategy enhanced mechanical strength and toughness while maintaining structural stability under physiological conditions. The Janus architecture was designed to support tissue integration on the hydrophilic side and reduce tissue adhesion on the hydrophobic side, contributing to reduced CSF leakage and tissue adhesion in a rat dural defect model. The membrane also showed favorable biocompatibility, slow degradation, and low swelling under the current experimental conditions. These findings suggest that the engineered PVA-based Janus membrane may serve as a promising candidate for further evaluation as a dural repair material.

Full text:

https://www.xiahepublishing.com/3067-6150/NSSS-2025-00045

The study was recently published in the Neurosurgical Subspecialties.

Neurosurgical Subspecialties (NSSS) is the official scientific journal of the Department of Neurosurgery at Union Hospital of Tongji Medical College, Huazhong University of Science and Technology. NSSS aims to provide a forum for clinicians and scientists in the field, dedicated to publishing high-quality and peer-reviewed original research, reviews, opinions, commentaries, case reports, and letters across all neurosurgical subspecialties. These include but are not limited to traumatic brain injury, spinal and spinal cord neurosurgery, cerebrovascular disease, stereotactic radiosurgery, neuro-oncology, neurocritical care, neurosurgical nursing, neuroendoscopy, pediatric neurosurgery, peripheral neuropathy, and functional neurosurgery.

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