Effects of Modified Magnetite Nanoparticles on Bacterial Cells and Enzyme Reactions

Abstract

Current paper presents biological effects of magnetite nanoparticles (MNPs). “Relations of MNP’ characteristics (zeta-potential and hydrodynamic diameters) with effects on bacteria and their enzymatic reactions were the main focus.”. Photobacterium phosphoreum and bacterial enzymatic reactions were chosen as bioassays. Three types of MNPs were under study: bare Fe3O4, Fe3O4 modified with 3-aminopropyltriethoxysilane (Fe3O4/APTES), and humic acids (Fe3O4/HA). Effects of the MNPs were studied at a low concentration range (< 2 mg/L) and attributed to availability and oxidative activity of Fe3+, high negative surface charge, and low hydrodynamic diameter of Fe3O4/HA, as well as higher Fe3+ content in suspensions of Fe3O4/HA. Low-concentration suspensions of bare Fe3O4 provided inhibitory effects in both bacterial and enzymatic bioassays, whereas the MNPs with modified surface (Fe3O4/APTES and Fe3O4/HA) did not affect the enzymatic activity. Under oxidative stress (i.e., in the solutions of model oxidizer, 1,4-benzoquinone), MNPs did not reveal antioxidant activity, moreover, Fe3O4/HA demonstrated additional inhibitory activity. The study contributes to the deeper understanding of a role of humic substances and silica in biogeochemical cycling of iron. Bioluminescence assays, cellular and enzymatic, can serve as convenient tools to evaluate bioavailability of Fe3+ in natural dispersions of iron-containing nanoparticles, e.g., magnetite, ferrihydrite, etc.

Toxicity and Antioxidant Activity of Fullerenol C60,70 with Low Number of Oxygen Substituents

“…It is supposed that oxidative toxicity is a function of redox activity of toxic media, while general toxicity is based on complex processes involving redox and polar/apolar interactions in the enzyme system. The data obtained earlier [33,50,53] showed higher sensitivity of T rel Ox to redox effects. Figure 3 shows that F10-12 detoxified the 1,4-benzoquinone solutions (I rel Ox > 1) in the narrow concentration range 10 -5 -4·10 −4 g L −1 (p < 0.05) with the maximal value of I rel Ox = 1.38; lower fullerenol concentrations did not significantly affect the I rel Ox than compared to the control (p > 0.05).…”

“…It should be mentioned that antioxidant effects of fullerenols were found at low and ultralow concentrations (<0.001 g L −1 ). It was shown in [53] that the bioluminescent enzymatic assay system can be additionally applied to monitor pro-oxidant effects of bioactive compounds.…”

Whither Magnetic Hyperthermia? A Tentative Roadmap

“…Since this section focuses only on essential characterization techniques for magnetic hyperthermia (MH) applications, it is worth noting that magnetic losses are strongly influenced by MNPs parameters such as size [17] and shape [18,19], aggregation degree [20,21] magnetic anisotropy [22], magnetic dipolar interactions [23,24], functionalization [25,26], viscosity of the dispersion medium [27,28], and alternating magnetic field conditions (field frequency and amplitude) [29][30][31]. Several EU projects focused on standardization and harmonization of analysis methods for MNPs have been/are being carried out, e.g., NanoMag, MagNaStand and RADIOMAG, as well as approved ISO standards (ISO/TS 19807-1:2019) [32,33].…”

“…The procedure is based on measuring the initial temperature increase rate immediately after applying the AC field. This experimental method has been widely employed and has contributed to understand the influence of intrinsic-structural, colloidal, magnetic-or extrinsic parameters-AC field-on SLP and ILP values [20,23,24,26,30,31,36,47,[56][57][58]63,[65][66][67][68]. Calorimetric measurements are usually performed under non-adiabatic conditions since adiabatic ones are rarely attained [69,70].…”

Advances in Nanotoxicology: Towards Enhanced Environmental and Physiological Relevance and Molecular Mechanisms

“…In another research article, Bondarenko et al assessed the biological effects of magnetite NPs on bacteria and their enzymatic reactions and the role of humic substances and silica in biogeochemical cycling of iron. The article also proposes whole-cell and enzyme-based bioluminescence assays as convenient tools to evaluate bio-availability of Fe(III) in natural dispersions of iron-containing NPs [ 4 ]. Development of novel cell-based toxicity assays was also the focus of the article by Semerad et al who addressed the issue of potential toxicity of NPs applied for remediation in soils and groundwater, to soil organisms [ 5 ].…”