Abstract
In this work, tunable nonwoven mats based on poly(3-hydroxybutyrate) (PHB) and type I collagen (Coll) were successfully produced by electrospinning. The PHB/Coll weight ratio (fixed at 100/0, 70/30, and 50/50, resp.) was found to control the morphological, thermal, mechanical, and degradation properties of the mats. Increasing collagen amounts led to larger diameters of the fibers (in the approximate range 600–900 nm), while delaying their thermal decomposition (from 245°C to 262°C). Collagen also accelerated the hydrolytic degradation of the mats upon incubation in aqueous medium at 37°C for 23 days (with final weight losses of 1%, 15%, and 23% for 100/0, 70/30, and 50/50 samples, resp.), as a result of increased mat wettability and reduced PHB crystallinity. Interestingly, 70/30 meshes were the ones displaying the lowest stiffness (~116 MPa; p < 0.05 versus 100/0 and 50/50 meshes), while 50/50 samples had an elastic modulus comparable to that of 100/0 ones (~250 MPa), likely due to enhanced physical crosslinking of the collagen chains, at least at high protein amounts. All substrates were also found to allow for good viability and proliferation of murine fibroblasts, up to 6 days of culture. Collectively, the results evidenced the potential of as-spun PHB/Coll meshes for tissue engineering applications.
Highlights
Electrospinning is a processing technique that allows the production of nonwoven mats of submicrometric polymer fibers, starting from various polymer solutions or blends
These findings were likely ascribed to the higher viscosity of the PHB/Coll blend resulting from increased collagen amounts and appeared in agreement with previous data on the synthesis of electrospun PDLLA/collagen fibers [13]
It is worth mentioning that an opposite effect of the collagen content on the fiber size has been documented in the literature for PHBV/collagen blends [10]
Summary
Electrospinning is a processing technique that allows the production of nonwoven mats of submicrometric polymer fibers, starting from various polymer solutions or blends. In addition to proper spatial organization, an ideal ECM-mimicking scaffold should possess bioactive functional groups able to bind cell ligands and potentially guide cellular behavior towards regeneration patterns This is why the electrospinning of natural polymers, directly derived from mammalian ECM (e.g., collagen, elastin, and hyaluronic acid), has been increasingly explored over the last 15 years [1,2,3,4,5,6]. We assumed that collagen could provide the electrospun mats with the necessary biomimetic cues and improved wettability, while PHB could control their stiffness and degradation rate, without the need for additional collagen-crosslinking treatments To test this hypothesis, we fabricated electrospun mats from three different PHB/Coll blends (having weight ratios of 100/0, 70/30, and 50/50, resp.) and characterized their morphological, chemical, thermal, mechanical, and degradation properties. Preliminary cell studies with murine fibroblasts were performed to evaluate the cytocompatibility of the proposed PHB/Coll substrates
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