The use of materials to restore or replace the functions of damaged body parts has been proven historically. Any material can be considered as a biomaterial as long as it performs its biological function and does not cause adverse effects to the host. With the increasing demands for biofunctionality, biomaterials nowadays may not only encompass inertness but also specialized utility towards the target biological application. A hydrogel is a biomaterial with a 3D network made of hydrophilic polymers. It is regarded as one of the earliest biomaterials developed for human use. The preparation of hydrogel is often attributed to the polymerization of monomers or crosslinking of hydrophilic polymers to achieve the desired ability to hold large amounts of aqueous solvents and biological fluids. The generation of hydrogels, however, is shifting towards developing hydrogels through the aid of enabling technologies. This review provides the evolution of hydrogels and the different approaches considered for hydrogel preparation. Further, this review presents the plasma process as an enabling technology for tailoring hydrogel properties. The mechanism of plasma-assisted treatment during hydrogel synthesis and the current use of the plasma-treated hydrogels are also discussed.

Titanium nitride/nitrogen-doped titanium oxide (TiN/N-doped TiO2) composite films were synthesized for visible light photodegradation applications. Thin films of TiN were sputter-deposited on precleaned glass substrates in an admixture of argon and nitrogen gases. The grown TiN films were subsequently oxidized in air at 350 °C at 15, 30, and 60 min. Raman spectral analysis revealed the formation of TiO2 with anatase structure at 15 min and transitioned to the rutile structure at longer oxidation times. X-ray photoelectron spectral analysis revealed the formation of N-doped TiO2 from the oxidized Ti. Visible light-induced photodegradation of methylene blue as test analyte showed 30% removal efficiency after exposure to visible light after 2.5 h. The highest degradation efficiency was observed when the anatase phase of TiO2 is the dominant phase in the film. Moreover, N-doping realized the visible light sensitivity of TiO2. This makes the composite film ideal for solar light-driven photodegradation of organic contaminants in wastewater.