Investigating the Effectiveness of Wheat Starch and Polymeric Additives on the Production of Biomedical Thermoplastic Starch Composites

Abstract

The presence of natural polymers as biomaterials has had a desirable efficacy on the development and progress of medical science research. Starch is a natural polymer that is abundant in nature, cost-effective, biodegradable, biocompatible, and non-toxic that has been recognized as a biomaterial with the potential to use in tissue engineering and pharmaceutical various fields of experiments. Practically, numerous hydrogen bonds amongst starch macromolecules make starch decompose, before reaching the melting point, under rising temperature conditions. This property can limit the usage of starch in different situations of research, however by modifying starch to thermoplastic starch (TPS), the mentioned problem can almost be solved. Conversion of starch to TPSs, improve the raw starch’s physical, chemical, mechanical, and functional abilities, which is the first aim of the research, where the next goal of the study is to evaluate the effects of different type and the ratio of plasticizers in fabricated TPS films’ mechanical and chemical properties to be able to choose the right options for use in tissue engineering research. Starch granules in the presence of water, heat, and shear condition by mixing with plasticizers like glycerol and D-sorbitol, which are approved by the Food and Drug Administration (FDA), undergo disruption, which causes a homogeneous melt named TPS. The last aim of the current research is to investigate TPS films’ biocompatibility and cytotoxicity properties by seeding normal human dermal fibroblast (n-HDF) cells on them. In this study, Thermoplastic wheat starch (TPS) films were fabricated with 30% to 70% total plasticizer with different ratios of glycerol and D-sorbitol by solution casting method. Wheat starch due to its higher amylose content which can increase tensile strengths and young's modulus of the TPS was selected in fabricating the TPS films. The plasticizers portion of the films was altered from 30% to 70% depending on the starch weight (3 g). After the mechanical test, from this point of view, six TPS films were selected for the advanced analysis due to their pioneer mechanical properties. Generally, TPS Films with total plasticizers of 30% and 40% presented higher tensile strength, toughness, and elastic modulus values in comparison to films with a total plasticizer of 50%, 60%, and 70%. Increment in the ratio of the D-sorbitol to glycerol in TPS films with equal total plasticizers had led to higher density value and thermal stability, however, reduces moisture absorption, and hydrolytic degradation ratio of the TPS films. Three groups of the films with 60% (20S-40G), 50% (20S-30G), and 40% (10S-30G) plasticizers, presented higher biocompatibility and proper surfaces for cells adhesion and proliferation, from the normal human dermal fibroblast cells viability analysis. Overall, TPS films showed better mechanical and physical properties at lower percentages of plasticizer, on the contrary, in cell studies, an increment in the percentages of plasticizers led to higher cell adhesion and viability, therefore increasing the biocompatibility of the TPS films.