Metal Oxide Nanoparticles: Review of Synthesis, Characterization and Biological Effects

Abstract

In the last few years, the progress made in the field of nanotechnology has allowed researchers to develop and synthesize nanosized materials with unique physicochemical characteristics, suitable for various biomedical applications. Amongst these nanomaterials, metal oxide nanoparticles (MONPs) have gained increasing interest due to their excellent properties, which to a great extent differ from their bulk counterpart. However, despite such positive advantages, a substantial body of literature reports on their cytotoxic effects, which are directly correlated to the nanoparticles’ physicochemical properties, therefore, better control over the synthetic parameters will not only lead to favorable surface characteristics but may also increase biocompatibility and consequently lower cytotoxicity. Taking into consideration the enormous biomedical potential of MONPs, the present review will discuss the most recent developments in this field referring mainly to synthesis methods, physical and chemical characterization and biological effects, including the pro-regenerative and antitumor potentials as well as antibacterial activity. Moreover, the last section of the review will tackle the pressing issue of the toxic effects of MONPs on various tissues/organs and cell lines.

Energy transfer and charge transfer between semiconducting nanocrystals and transition metal dichalcogenide monolayers

“…61,62 Considering metal oxide nanoparticles (MONPs) as a case study, synthesis methods can be classified into two groups: (i) physical methods, such as ball milling, sputtering, laser ablation, electrospraying, and electron beam evaporation, and (ii) chemical methods, such as colloidal synthesis, non-thermal plasma assisted synthesis, sol-gel method, polyol method, hydrothermal method, co-precipitation method, microemulsion technique, and chemical vapor deposition. [63][64][65] Physical methods follow a top-down strategy, where NPs are generated from the bulk counterpart of a material through systematic depletion. On the other hand, chemical methods primarily adopt a bottom-up approach, involving the assembly of atoms or molecules to form NPs of various sizes.…”

Microwave Synthesis of Visible-Light-Activated g-C3N4/TiO2 Photocatalysts

“…Several approaches have already been used to fabricate g-C 3 N 4 /TiO 2 heterostructures, such as sol-gel [ 65 ], hydrothermal [ 58 ]/solvothermal syntheses [ 66 ], wet impregnation [ 67 ] and microwave-assisted methods [ 68 , 69 ]. Apart from the microwave irradiation process, these methods typically require high temperatures and/or long reaction times, hence being energy consuming [ 58 , 66 , 67 , 70 , 71 ]. Taking into account the minimization of energy, microwave irradiation appears as a good alternative for the synthesis of complex inorganic materials, since higher reaction yields can be obtained in such a short amount of time.…”

Rhodamine B photocatalytic activity and the synthesis of Zinc Oxide and Titanium Dioxide nanoparticles mediated by Vachellia hebeclada (Acacia hebeclada).

“…The extract reduces and stabilizes the mixture, resulting in precisely controlled size and shape nanoparticles. Flavonoids, terpenoids, and phenolics' natural compounds found in V. hebeclada extracts serve as reducing and capping agents assisting in the stabilization of metal ions like Zn 2+ and Ti 4+ and preventing agglomeration [9]. Under UV light, these nanoparticles have demonstrated promising photocatalytic activity for RhB degradation.…”

“…→ H 2 O 2 + 2OH − + O 2 (7) H 2 O 2 + e − → • OH + OH − (8) O 2•− + RhB → non-toxic or less-toxic products(9) …”