Sustainable Vegetable Oil-Based Biomaterials: Synthesis and Biomedical Applications

One of the main criteria for ecological sustainability is that the materials produced for common use are green. This can include the use of biomaterials and materials that are environmentally friendly, biodegradable and produced at low cost. The exploration of natural resources as sustainable precursors leads to the production of biopolymers that are useful for 3D printing technology. Recently, waste vegetable oils have been found to be a good alternative source for the production of biopolymers in various applications from the engineering to the biomedicine. In this review, the processes for the synthesis of vegetable oil-based biomaterials are described in detail. Moreover, the functionalization strategies to improve the mechanical properties of these materials and the cell-material interaction for their potential use as micro-structured scaffolds in regenerative medicine are discussed.

Upcycling of semicrystalline polymers by compatibilization: mechanism and location of compatibilizers

With the continuous increase of global plastics production, there is a demand to develop energy efficient processes to transform mixed plastic wastes into new products with enhanced utility - a concept that is often referred to as upcycling. Compatibilization is one of the most promising strategies to upcycle communal waste plastics. In this work, poly(ethylene terephthalate) (PET) and high-density polyethylene (HDPE), both widely used semicrystalline packaging polymers, are used as the target polymer blend. We systematically evaluate and compare three commercial ethylene copolymer based compatibilizers, ELVALOY™ AC 2016 Acrylate Copolymer (EAA), ELVALOY™ PTW Copolymer (PTW), and SURLYN™ 1802 Ionomer (Surlyn). They represent different compatibilization mechanisms. Furthermore, this work tackles a challenging question: where the compatibilizers are located in the blend. We discover that the location of the compatibilizer molecules can be predicted by comparing the crystallinity change of PET and HDPE in binary and ternary systems. Gaining this knowledge will facilitate root cause analysis of an ineffective compatibilizer and guide the design strategy to upcycle commingled waste plastics.

Kinetical Study, Thermo-Mechanical Characteristics and Recyclability of Epoxidized Camelina Oil Cured with Antagonist Structure (Aliphatic/Aromatic) or Functionality (Acid/Amine) Hardeners

In an attempt to prepare sustainable epoxy thermosets, this study introduces for the first time the idea to use antagonist structures (aromatic/aliphatic) or functionalities (acid/amine) as hardeners to produce reprocessable resins based on epoxidized camelina oil (ECMO). Two kinds of mixtures were tested: one combines aromatic/aliphatic dicarboxylic acids: 2,2'-dithiodibenzoic acid (DTBA) and 3,3'-dithiodipropionic acid (DTDA); another is the combination of two aromatic structures with acid/amine functionality: DTBA and 4-aminophenyl disulfide (4-AFD). DSC and FT-IR analyses were used as methods to analyze the curing reaction of ECMO with the hardeners. It was found that the thermosets obtained with the dual crosslinked mechanism needed reduced curing temperatures and reprocessing protocols compared to the individual crosslinked thermosets. Thanks to the contribution of disulfide bonds in the network topology, the obtained thermosets showed recycling ability. The final thermomechanical properties of the virgin and mechanical reprocessed materials were analyzed by DMA and TGA. The obtained thermosets range from elastomeric to rigid materials. As an example, the ECMO/DTBA704-AFD30 virgin or reprocessed thermosets have tan δ values reaching 82-83 °C. The study also investigates the chemical recycling and the solvent resistance of these vitrimer-like materials.

New Impedimetric Sandwich Immunosensor for Ultrasensitive and Highly Specific Detection of Spike Receptor Binding Domain Protein of SARS-CoV-2

An impedance sensing platform-combined conducting nanocomposite layer was fabricated to develop an effective and rapid method for detection of coronavirus infection (COVID-19) specific spike receptor binding domain (RBD) protein, a precious antigen marker of COVID-19 disease. Coronavirus infection has spread globally and swiftly with major impacts on health, economy, and quality of life of communities. Fast and reliable detection of COVID-19 is a very significant issue for the effective treatment of this bad illness. For this aim, first, an Epoxy functional group-substituted thiophene monomer was synthesized and electrodeposited on a single-use indium tin oxide (ITO) platform in the presence of acetylene black by employing a cyclic voltammetry technique; thus, a conducting nanocomposite (C-NC) layer with high conductivity was obtained. This composite was electrodeposited for the first time on the ITO surface to generate a facile and cost-effective impedimetric biosensor. In addition, this composite provided proper attachment points for antibody binding and also supported the biosensor construction. The immuno-specific biointeractions between anti-RBD and RBD proteins hampered the electron transfer between the ITO substrate surface and electrolyte, and this reaction caused variations in impedance signals, and these signals were proportional to the immobilized RBD antigen amounts. The as-prepared immunosensor showed a wide linear dynamic range (0.0012-120 pg/mL), an ultra-low detection limit of 0.58 fg/mL with added superiorities of great selectivity, suitable repeatability, multiple reusability, and excellent reproducibility.

Influence of the Presence of Disulphide Bonds in Aromatic or Aliphatic Dicarboxylic Acid Hardeners Used to Produce Reprocessable Epoxidized Thermosets

The design of polymers from renewable resources with recycling potential comes from economic and environmental problems. This work focused on the impact of disulphide bonds in the dicarboxylic acids reactions with three epoxidized vegetable oils (EVOs). For the first time, the comparison between aromatic vs. aliphatic dicarboxylic acids, containing or not S-S bonds with EVOs was discussed and evaluated by dynamic scanning calorimetry. The obtained thermosets showed reprocessability, by the dual dynamic exchange mechanism. The virgin and reprocessed materials were characterized and the thermomechanical properties were compared. The thermosets derived from EVOs with high epoxy content combined with aromatic diacids containing disulphide bridges showed high glass transition values (~111 °C), high crosslink densities and good solvent stability.