Due to their particular water absorption capacity, hydrogels are the most widely used scaffolds in biomedical studies to regenerate damaged tissue. Hydrogels can be used in tissue engineering to design scaffolds for three-dimensional cell culture, providing a novel alternative to the traditional two-dimensional cell culture as hydrogels have a three-dimensional biomimetic structure. This material property is crucial in regenerative medicine, especially for the nervous system, since it is a highly complex and delicate structure. Hydrogels can move quickly within the human body without physically disturbing the environment and possess essential biocompatible properties, as well as the ability to form a mimetic scaffold in situ. Therefore, hydrogels are perfect candidates for biomedical applications. Hydrogels represent a potential alternative to regenerating tissue lost after removing a brain tumor and/or brain injuries. This reason presents them as an exciting alternative to highly complex human physiological problems, such as injuries to the central nervous system and neurodegenerative disease.

Polymer composite materials based on polylactic acid (PLA) filled with titanium dioxide (TiO₂) nanoparticles were prepared. The aim of this work was to investigate the antibacterial action of TiO₂ against a strain of E. coli (DH5α) to obtain information on their potential uses in food and agro-alimentary industry. PLA/TiO₂ systems were prepared by a two-step process: Solvent casting followed by a hot-pressing step. Characterization was done as a function of particle size (21 nm and <100 nm) and particle content (0%, 1%, 5%, 10%, and 20%, wt %). Structural characterization carried out by X-ray diffraction (XRD) and Fourier Transformed Infrared spectroscopy (FTIR) did not reveal significant changes in polymer structure due to the presence of TiO₂ nanoparticles. Thermal characterization indicated that thermal transitions, measured by differential scanning calorimetry (DSC), did not vary, irrespective of size or content, whereas thermogravimetric analysis (TGA) revealed a slight increase in the temperature of degradation with particle content. Bacterial growth and biofilm formation on the surface of the composites against DH5α Escherichia coli was studied. Results suggested that the presence of TiO₂ nanoparticles decreases the amount of extracellular polymeric substance (EPS) and limits bacterial growth. The inhibition distances estimated with the Kirby-Bauer were doubled when 1% TiO₂ nanoparticles were introduced in PLA, though no significant differences were obtained for higher contents in TiO₂ NPs.

Metallic nanoparticles (NPs) possess unique physicochemical properties that have enabled their engineering for loading drugs, contrast agents, and targeting moieties for cellular and intracellular components, highlighting their emerging role as versatile tools in managing neurological disorders. In therapeutic applications, the surface plasmon resonance characteristics of gold and silver NPs and the responsiveness of magnetic nanoparticles (MNPs) to external magnetic fields facilitate the disruption of protein aggregates and the eradication of cancer cells. For diagnostic purposes, the inherent high electron density of metallic NPs makes them effective contrast agents in imaging technologies. Moreover, these NPs have proven their capability to traverse the blood–brain barrier (BBB) and interact with central nervous system (CNS) components. Despite their extensive scientific exploration and promising applications, metallic NPs have not yet achieved widespread clinical implementation, especially in comparison to polymer‐based NPs. This article presents an in‐depth examination of the physicochemical properties of metallic NPs relevant to neurological applications. It summarizes their roles in diagnosis and therapy, focusing on gold, magnetic, silver, titanium, and cerium NPs. Additionally, this document explains the incorporation of metal NPs in their application and their effect on the human body.