Abstract
Polyvinyl alcohol (PVA) hydrogels have been widely studied for cartilage replacement due to their biocompatibility, chemical stability, and ability to be modified such that they approximate natural tissue behavior. Additionally, they may also be used with advantages as local drug delivery systems. However, their properties are not yet the most adequate for such applications. This work aimed to develop new PVA-based hydrogels for this purpose, displaying improved tribomechanical properties with the ability to control the release of diclofenac (DFN). Four types of PVA-based hydrogels were prepared via freeze-thawing: PVA, PVA/PAA (by polyacrylic acid (PAA) addition), PVA/PAA+PEG (by polyethylene glycol (PEG) immersion), and PVA/PAA+PEG+A (by annealing). Their morphology, water uptake, mechanical and rheological properties, wettability, friction coefficient, and drug release behavior were accessed. The irritability of the best-performing material was investigated. The results showed that the PAA addition increased the swelling and drug release amount. PEG immersion led to a more compact structure and significantly improved the material’s tribomechanical performance. The annealing treatment led to the material with the most suitable properties: besides presenting a low friction coefficient, it further enhanced the mechanical properties and ensured a controlled DFN release for at least 3 days. Moreover, it did not reveal irritability potential for biological tissues.
Highlights
Osteoarthritis (OA) is the most common chronic joint condition, affecting more than 300 million people worldwide [1]
Polyvinyl alcohol (PVA)-based hydrogels were produced to be used as cartilage replacement materials
Aiming to improve their tribomechanical behavior and to provide them with the ability to act as drug release platforms of the anti-inflammatory drug DFN, several approaches were followed: (1) polyacrylic acid (PAA) was added to the formulation of hydrogels to obtain PVA/PAA samples; (2) PVA/PAA was further immersed in polyethylene glycol (PEG) to obtain PVA/PAA+PEG samples; (3) PVA/PAA+PEG was annealed at 120 ◦C, giving rise to PVA/PAA+PEG+A samples
Summary
Osteoarthritis (OA) is the most common chronic joint condition, affecting more than 300 million people worldwide [1]. FT produces highly porous, spongy, and rubbery materials through a cyclic process of freezing and thawing This method promotes chain reticulation via liquid–liquid phase separation, hydrogen bonding, and crystallite formation [16,17]. FT PVA hydrogels generally produces a greater swelling capacity but a lower elastic modulus and less resistance to wear than natural cartilage. Their properties may be improved by changing the number and duration of FT cycles [12], alternative reinforcement strategies have been attempted to enhance the materials’ mechanical performance. These include the incorporation of other polymers of synthetic (e.g., poly(lactic-co-glycolic acid, poly(ethylene glycol) diacrylate, polyvinylpyrrolidone) or natural origin (e.g., collagen, hyaluronic acid, chitosan, alginate) [18,19]; nano/microparticles (e.g., silica and hydroxyapatite) [20,21] and other differentiated structures (e.g., graphene sheets) [22]; and the use of physical treatments, such as thermal annealing [23]
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