Semiconductor photocatalysts, particularly ZnO nanoparticles, were synthesized via the precipitation method using four different precursors (zinc acetate/zinc nitrate/zinc sulfate/zinc chloride) and compared, according to their optical, structural, photocatalytic, and anticancer properties. The materials were characterized via X-ray Diffraction method (XRD), micro-Raman, Fourier Transform Infrared Spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET), Dynamic Light Scattering (DLS), and Field Emission Scanning Electron Microscope (FESEM) analysis. Photocatalysis was conducted under UV and visible light irradiation, using Rhodamine B as the organic pollutant. It was observed that the highest photocatalysis efficiency was obtained by the nanoparticles synthesized from the zinc acetate used as precursor material. A cell-dependent anticancer efficiency of the tested ZnO nanoparticles was also observed, that was also attributed to the different precursors and the synthesis method, revealing that the nanoparticles that were synthesized from zinc acetate were more bioactive among the four tested precursors. Overall, the data revealed that both the enhanced photocatalytic and biological activity of ZnO nanoparticles derived from zinc acetate precursor could be attributed to the reduced crystalline size, increased surface area, as well as the observed hexagonal crystalline morphology.

This review study aims to present, in a condensed manner, the significance of the use of crystalline carbon-based nanomaterials in biomedical applications. Crystalline carbon-based nanomaterials, encompassing graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, and graphene quantum dots, have emerged as promising materials for the development of medical devices in various biomedical applications. These materials possess inorganic semiconducting attributes combined with organic π-π stacking features, allowing them to efficiently interact with biomolecules and present enhanced light responses. By harnessing these unique properties, carbon-based nanomaterials offer promising opportunities for future advancements in biomedicine. Recent studies have focused on the development of these nanomaterials for targeted drug delivery, cancer treatment, and biosensors. The conjugation and modification of carbon-based nanomaterials have led to significant advancements in a plethora of therapies and have addressed limitations in preclinical biomedical applications. Furthermore, the wide-ranging therapeutic advantages of carbon nanotubes have been thoroughly examined in the context of biomedical applications.

The multifactorial nature of cancer still classifies the disease as one of the leading causes of death worldwide. Modern medical sciences are following an interdisciplinary approach that has been fueled by the nanoscale revolution of the past years. The exploitation of high-Z materials, in combination with ionizing or non-ionizing radiation, promises to overcome restrictions in medical imaging and to augment the efficacy of current therapeutic modalities. Gold nanoparticles (AuNPs) have proven their value among the scientific community in various therapeutic and diagnostic techniques. However, the high level of multiparametric demands of AuNP experiments in combination with their biocompatibility and cytotoxicity levels remain crucial issues. Gadolinium NPs (GdNPs), have presented high biocompatibility, low cytotoxicity, and excellent hemocompatibility, and have been utilized in MRI-guided radiotherapy, photodynamic and photothermal therapy, etc. Τhe utilization of gadolinium bound to AuNPs may be a promising alternative that would reduce phenomena, such as toxicity, aggregation, etc., and could create a multimodal in vivo contrast and therapeutic agent. This review highlights multi-functionalization strategies against cancer where gold and gadolinium NPs are implicated. Their experimental applications and limitations of the past 5 years will be analyzed in the hope of enlightening the benefits and drawbacks of their proper combination.