Use of Polyesters in Fused Deposition Modeling for Biomedical Applications

In recent years, 3D printing techniques experience a growing interest in several sectors, including the biomedical one. Their main advantage resides in the possibility to obtain complex and personalized structures in a cost-effective way impossible to achieve with traditional production methods. This is especially true for fused deposition modeling (FDM), one of the most diffused 3D printing methods. The easy customization of the final products' geometry, composition, and physicochemical properties is particularly interesting for the increasingly personalized approach adopted in modern medicine. Thermoplastic polymers are the preferred choice for FDM applications, and a wide selection of biocompatible and biodegradable materials is available to this aim. Moreover, these polymers can also be easily modified before and after printing to better suit the body environment and the mechanical properties of biological tissues. This review focuses on the use of thermoplastic aliphatic polyesters for FDM applications in the biomedical field. In detail, the use of poly(epsilon-caprolactone), poly(lactic acid), poly(lactic-co-glycolic acid), poly(hydroxyalkanoate)s, thermoplastic poly(ester urethane)s, and their blends is thoroughly surveyed, with particular attention to their main features, applicability, and workability. The state-of-the-art is presented and current challenges in integrating the additive manufacturing technology in the medical practice are discussed

Injectable thermosensitive gels for the localized and controlled delivery of biomolecules in tissue engineering/regenerative medicine

The characteristic poor stability and high fluid permeability of Poloxamer®- based gels have severely limited their biomedical application. In this work, Poloxamer 407 was used as building block to synthesize a poly(ether urethane) (PEU), which aqueous solutions formed gels with improved stability and mechanics compared to Poloxamer itself. PEU chains formed micelles in aqueous solution (diameter ~40 nm at 25°C) and systems with PEU content higher than 5±1% w/v underwent a temperature- driven gelation. Gel properties were tuned acting on PEU concentration in the starting solutions, with compositions within the range 8-18% w/v showing high potential for biomedical applications (gelation at 37°C within 3-10 minutes, residence time from few days to many weeks, injectability). Model proteins (bovine serum albumin, horseradish peroxidase) were encapsulated in mild conditions and their release was modulated by gel composition (on day 3, approx. 85, 65 and 55% of encapsulated payload released from gels with 8, 15 and 18% w/v concentration). Released peroxidase retained approx. 30-40% of its activity up to 2 days, a key aspect for biomolecules in the drug delivery field

Designing 3D bioengineered in vitro cardiac tissue models as reliable tools for the evaluation of chemical cardiotoxicity

Humans are continuously exposed to a huge amount and a variety of chemicals. Animal tests are the gold standard for toxicity testing. However, they often fail in finely replicating the real physio-pathological scenario, and their use is associated with ethical issues. Thus, there is an urgent need for Novel Approach Methodologies providing more reliable and robust methods for toxicity assessment