Hydrogels are three-dimensional polymer networks that are hydrophilic and capable of retaining a large amount of water.

A significant amount of plastic trash has been dumped into the environment across the world, contributing to the present white pollution crisis.

Orthopedic implants are an important tool in the treatment of musculoskeletal conditions and helped many patients to improve their quality of life. Various inorganic-organic biocomposites have been broadly investigated particularly in the area of load-bearing orthopedic/dental applications. Polyimide (PI) is a promising organic material and shows excellent mechanical properties, biocompatibility, bio-stability, and its elastic modulus is similar to human bone but it lacks bioactivity, which is very important for cell adhesion and ultimately for bone regeneration. In this research, tantalum pentoxide (Ta₂O₅) coating was prepared on the surface of PI by polydopamine (PDA) bonding. The results showed that Ta₂O₅ was evenly coated on the surface of PI, and with the concentration of Ta₂O₅ in the PDA suspension increased, the content of Ta₂O₅ particles on the surface of PI increased significantly. In addition, the Ta₂O₅ coating significantly increased the roughness and hydrophilicity of the PI matrix. Cell experiments showed that PI surface coating Ta₂O₅ could promote the proliferation, adhesion, and osteogenic differentiation of bone marrow-derived stromal cells (BMSCs). The results demonstrated that fabricating Ta₂O₅ coating on the surface of PI through PDA bonding could improve the biocompatibility as well as bioactivity of PI, and increase the application potential of PI in the field of bone repair materials.

Guar esters of long-chain aliphatic carboxylic acids (fatty acid) were prepared and examined. Esterification was done in two steps, with the first goal to prepare acid chloride by refluxing acid with slight excess of thionyl chloride, and the product was confirmed by elemental analysis. Ten different types of fatty acid (C5-C18) were used for derivatization. The reaction mechanism for synthesis of fatty acid ester of guar was studied in detail. Physical properties of the esters were examined as well. The degree of substitution was calculated by titration method and structure elucidation was done using Fourier transform infrared spectroscopy (FTIR), proton-nuclear magnetic resonance (1H-NMR) and scanning electron microscopy (SEM) techniques.