Free radicals are generated as byproducts of normal metabolic processes as well as due to exposure to several environmental pollutants. They are highly reactive species, causing cellular damage and are associated with a plethora of oxidative stress-related diseases and disorders. Antioxidants can control autoxidation by interfering with free radical propagation or inhibiting free radical formation, reducing oxidative stress, improving immune function, and increasing health longevity. Antioxidant functionalized metal nanoparticles, transition metal oxides, and nanocomposites have been identified as potent nanoantioxidants. They can be formulated in monometallic, bimetallic, and multi-metallic combinations via chemical and green synthesis techniques. The intrinsic antioxidant properties of nanomaterials are dependent on their tunable configuration, physico-chemical properties, crystallinity, surface charge, particle size, surface-to-volume ratio, and surface coating. Nanoantioxidants have several advantages over conventional antioxidants, involving increased bioavailability, controlled release, and targeted delivery to the site of action. This review emphasizes the most pioneering types of nanoantioxidants such as nanoceria, silica nanoparticles, polydopamine nanoparticles, and nanocomposite-, polysaccharide-, and protein-based nanoantioxidants. This review overviews the antioxidant potential of biologically synthesized nanomaterials, which have emerged as significant alternatives due to their biocompatibility and high stability. The promising nanoencapsulation nanosystems such as solid lipid nanoparticles, nanostructured lipid carriers, and liposome nanoparticles are highlighted. The advantages, limitations, and future insights of nanoantioxidant applications are discussed.

Aims Investigate the capability of Aspergillus brasiliensis ATCC 16404 to mycosynthesize Co₃O₄‐NPs. Methods and results Mycelial cell free filtrate of Aspergillus brasiliensis ATCC 16404, was applied for mycosynthesis of Co₃O₄‐NPs. The preliminary indication for the formation of Co₃O₄‐NPs was the change in color from yellow to reddish‐brown color. One‐factor‐at a time‐optimization technique was applied to determine the optimum physicochemical conditions required for the mycosynthesis of Co₃O₄‐NPs and they were found to be; 72 h for reaction time, 11 for pH, 30ºC for temperature, 100 rev.min^‐1 for shaking speed in the darkness using 4 mmol l^‐1 of CoSO_4.7H₂O and 5·5% of A. brasiliensis dry weight mycelium (w/v). The mycosynthesized Co₃O₄‐NPs were characterized using various techniques, spectroscopic including; UV/Vis spectrophotometry; dynamic light scattering, zeta potential measurement, energy dispersive X‐ray analysis, Fourier transform infrared spectroscopy, and X‐ray diffraction, vibrating sample magnetometry and microscopic including; field emission scanning electron microscopy and high resolution transmission electron microscopy. Spectroscopic techniques confirmed the formation of Co₃O₄‐NPs and the microscopic ones confirmed the shape and size of the mycosynthesized Co₃O₄‐NPs as quasi‐spherical shaped, monodispersed nanoparticles with a nano size range of 20 to 27 nm. The mycosynthesized Co₃O₄‐NPs have excellent magnetic properties and exhibited a good antimicrobial activity against some pathogenic microorganisms. Conclusion Ferromagnetic Co₃O₄‐NPs with considerable antimicrobial activity were for the first time mycosynthesized. Significance and Impact of Study The use of fungi as potential bionanofactories for mycosynthesis of nanoparticles is relatively a recent field of research with considerable prospects.