Monodisperse Fe₂O₃ Supraparticles: Eco‐Friendly Fabrication, Gallic Acid Modification, Size‐Dependent Photothermal Conversion Efficiency, and Cellular Uptake

Abstract

For example, soft-template fabrication is one of representative methods for various inorganic SPs, [4c,5] which however possess two typical problems of two-step fabrication systems. First of all, they need lots of organic solvents and surfactants, which inevitably results in environmental concerns. Then, monodispersity of the resultant products is often not ideal, causing some difficulty in their property studies and applications. [1b,6] To address these issues, we previously developed a self-limited strategy for onestep in situ fabricating various (CdS, CdSe, ZnS, PbS, Au@CdSe core@shell, etc.) SPs with narrow size distribution. [7] Because the SPs are self-assembled based on the intrinsic forces among the building blocks, any surfactants and organic solvents are completely needless. Correspondingly, the fabrication processes are carried out in 100% water solutions. Then, to be appropriate for biomedical applications, a few modified fabrication systems have been further explored for the corresponding SPs. [3c,d] Especially, we recently presented a urea modulated system for in situ fabricating citrate modified Fe 2 O 3 SPs. The products are quasi-amorphous, 15 nm in diameter, and have the capacities for active T 1-weighted magnetic resonance imaging (MRI) in vivo. [8] As a new-type of SPs, it is significant to well understand their fabrication approach, engineer their surface chemistry, as well as explore their new application potentials. In this study, we systematically study the eco-friendly fabrication system of the hierarchical Fe 2 O 3 SPs. First, by means of urea as pH modulator, monodisperse Fe 2 O 3 SPs with 7 to 90 nm in diameters can be one-step in situ self-assembled in 100% water solution. Then, in addition to citrate, it is found that the SPs can be fabricated by various carboxyl stabilizers, indicating the versatility of the proposed fabrication system. Third, by means of gallic acid (GA) modification, the corresponding products (denoted as Fe 2 O 3 @GA SPs) can be endowed nearinfrared light-absorbing properties and subsequent photothermal therapy potentials. Fourth, the Fe 2 O 3 @GA SPs exhibit size-dependent photothermal performances and cellular uptake. In terms of 8 nm sized Fe 2 O 3 @GA SPs, their photothermal conversion efficiency and cellular uptake are 66.63% and 8.4 pg Fe/cell, which are well higher than that of 25 and 47 nm sized products. In this study, the eco-friendly fabrication system of the hierarchical monodisperse Fe 2 O 3 supraparticles (SPs) is systematically studied. First, by means of urea as pH modulator, monodisperse Fe 2 O 3 SPs with 7 to 90 nm in diameters can be one-step in situ self-assembled in 100% water solution. Then, the SPs can be reliably fabricated by various carboxyl stabilizers, indicating the versatility of the proposed fabrication system. Third, by means of gallic acid (GA) modification, the corresponding products (denoted as Fe 2 O 3 @GA SPs) can be endowed near-infrared light-absorbing properties and photothermal therapy potentials. Fourth, the Fe 2 O 3 @GA ...

Chain-Breaking Antioxidant and Peroxyl Radical Trapping Activity of Phenol-Coated Magnetic Iron Oxide Nanoparticles

“…This demonstrates that binding to the iron oxide surface hampers the ability of phenols to donate a H-atom to peroxyl radicals. At the same time, this observation suggests that metal–phenol binding could increase the stability of capping phenols in an oxidizing environment, thus also providing a stable capping in biological systems, as demonstrated in various studies [ 7 , 12 ]. Most importantly, phenol-capping avoids the prooxidant effect, which is instead observed with bare SPION.…”

“…Phenols were chosen to cover different class of antioxidants presenting in nature and typically employed in SPIONs synthesis. Gallic acid (GA) is a versatile antioxidant with anticancer, anti-melanogenic and anti-steatosis applications [ 30 , 31 ] and was previously used as capping agent for SPION [ 7 ]. Nordihydroguaiaretic acid (NDGA) is a natural phenolic lignan known for its lipoxygenase-inhibiting properties [ 32 ] and is actively investigated for its promising activity against chronic diseases [ 33 ].…”

“…Phenols and polyphenols have long been used as surface modifiers of SPION, due to their affinity to iron ions, positive influence on the overall magnetization of the nanoparticle, and the possibility of using them as a reductant during the synthesis [ 6 ]. Examples reported in the literature are mainly represented by bidentate catechol derivatives comprising gallic acid [ 7 ], gallotannins [ 8 ], dopamine [ 9 ], caffeic acid [ 10 ], quercetin [ 11 ] and monophenols with acid functionalities that can help to bind the metal surface, such as curcumin [ 12 ] and 2-hydroxyisophthalic acid [ 13 ]. Because of the widespread presence of polyphenols in the vegetal kingdom, a number of protocols employing plant extracts functioning at the same time as reductant and surface capping agents have been proposed [ 14 , 15 ].…”

Versatile fabrication of metal sulfide supraparticles by an in situ decomposition–assembly strategy

“…The size of the nanomaterials greatly inuences their emerging physical and chemical properties, 6,34 as well as their performances in related application areas, for instance, the uptake and resulting function of the cell, the mechanism of endocytosis, and the toxicity. [35][36][37] Through tuning the proportion of cysteine and metal ions, the size of obtained SPs can be rationally designed.…”

“…4 Secondly, apart from the properties of nanoparticles, emerging physical and chemical properties are expected in SPs due to the opto-electronic coupling between the building blocks. 5 What's more, SP properties could be accurately modulated by various parameters such as nanoparticle size, 6 morphology, 7,8 arrangement, 9 composition, 10,11 etc. Finally, functional SPs with definite size, morphology, and hierarchical topology have demonstrated enormous application potentials in various fields, like energy, medicine, and biology.…”