Abstract
The unique lignocellulosic and solvent-extractive chemical constituents of most natural fibers are rich in natural polymers and bioactive molecules that can be exploited for biomaterial formulation. However, although natural fibers’ main constituents have been already incorporated as material reinforcement and improve surface bioactivity of polymeric materials, the use of the whole natural fibers as bioactive fillers remains largely unexplored. Thus, we put forward the formulation of natural fiber filling and functionalization of biomaterials by studying the chemical composition of cocoa bean shells (CBS) and proposing the fabrication and characterization of polylactic acid (PLA) and CBS-based composite by solvent-casting. As was expected from previous studies of agro-industrial wastes, the main components of CBS were to cellulose (42.23 wt.%), lignin (22.68 wt.%), hemicellulose (14.73 wt.%), and solvent extractives (14.42 wt.%). Structural analysis (FTIR) confirms the absence of covalent bonding between materials. Thermal degradation profiles (DSC and TGA) showed similar mass losses and thermal-reaction profiles for lignocellulosic-fibers-based composites. The mechanical behavior of the PLA/CBS composite shows a stiffer material behavior than the pristine material. The cell viability of Vero cells in the presence of the composites was above 94%, and the hemolytic tendency was below 5%, while platelet aggregation increased up to 40%. Antioxidant activity was confirmed with comparable 2,2-diphe-277 nyl-1-picryl-hydrazyl-hydrate (DPPH) free-radical scavenging than Vitamin C even for PLA/CBS composite. Therefore, the present study elucidates the significant promise of CBS for bioactive functionalization in biomaterial-engineering, as the tested composite exhibited high biocompatibility and strong antioxidant activity and might induce angiogenic factors’ release. Moreover, we present an eco-friendly alternative to taking advantage of chocolate-industry by-products.
Highlights
Synthetic polymers (SP) have become a part of our daily routine; their extended use has brought several concerns about long-term effects, the sustainability of manufacturing technologies involved, and end-of-life disposal [1,2]
cocoa bean shells (CBS) was found to be mainly composed of cellulose (42.23 ± 1.93 wt.%), lignin (22.68 ± 1.17 wt.%), hemicellulose (14.73 ± 1.57), and solvent-extractives (14.42 ± 1.94), leading to its classification as grass and reed fiber [40,41]
CBS’s composition makes it suitable as a composites filler, since mechanical properties mainly depend on the cellulose content [42,43]
Summary
Synthetic polymers (SP) have become a part of our daily routine; their extended use has brought several concerns about long-term effects, the sustainability of manufacturing technologies involved, and end-of-life disposal [1,2]. To address some of these issues, over the last decades, natural polymers (NP) from renewable resources have emerged as an attractive alternative due to their ease of degradation, low environmental impact, and high biocompatibility. This has resulted in a growing number of engineering applications, including packing, construction, and tissue-inspired biomaterials [2,3]. NP has shown excellent performance when used as a replacement of SP in many applications, including packaging (bags and foams) [4], agricultural mulch [5], and medical devices (i.e., scaffolds for regenerative medicine, synthesis of nano vehicles for drug delivery, etc.) [6]. Some approaches have been successfully explored by using NPs as resorbable and biocompatible composite scaffolds for the treatment of damaged tissues, despite their absence of surface bioactivity [6,7]
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