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Analytical Tools Able to Detect ENP/NM/MNs in both Artificial and Natural Environmental Water Media
Published in Julián Blasco, Ilaria Corsi, Ecotoxicology of Nanoparticles in Aquatic Systems, 2019
Site specific risk assessment of ENPs requires spatially resolved fate models. Validation of such models is difficult due to present limitations in detecting ENPs in the environment. An interesting study showed the progress towards validation of the spatially resolved hydrological ENP fate model NanoDUFLOW, by comparing measured and modeled concentrations of < 450 nm metal-based particles in river’s waters (De Klein et al. 2016). Concentrations measured with Asymmetric Flow-Field-Flow Fractionation (AF4) coupled to ICP-MS clearly reflected the hydrodynamics of the river and showed satisfactory to good agreement with modeled concentration profiles. Together with the general applicability of the model framework, this legitimizes an optimistic view on the potential to validate such models, with important implications for the risk assessment of ENPs (De Klein et al. 2016).
Characterization Methods for Nanoparticles
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
R. Gopirajah, C. Anandharamakrishnan
Hagendorfer et al. (2012) studied the silver nanoparticle product characteristics using asymmetric flow field flow fractionation and comparing the results with TEM. The method applies a multidetector approach (UV/vis, light scattering, inductively coupled plasma mass spectrometry – ICPMS), and the results show FFF is a powerful and reliable technique for a quantitative-, size-, and mass-specific characterization of polydisperse engineered Ag-NP products. In comparison with TEM, FFF offers faster measurement times and the ability to determine the samples directly in dispersions. FFF has been used to determine the mass of proteins and size of colloidal carriers, including liposomes, injectable emulsions, and particles (Janča, 2006). The limitations of FFF techniques are potential membrane swelling, membrane interactions, the continuous re-equilibration in the channel, the need (in some circumstances) of preconcentration, the additional concentration of the sample during equilibration, and the possibility of aggregation in the channel (Heera and Shanmugam, 2015; Hagendorfer et al., 2012).
Effect of Nanoparticles on Gastrointestinal Tract
Published in V Ravishankar Rai, Jamuna A. Bai, Nanotechnology Applications in the Food Industry, 2018
Jamuna A. Bai, V Ravishankar Rai
The migration of Ag NPs from food contact polyolefins into food has been investigated using ICP-MS. Low-density PE (LDPE) films incorporated with different concentrations of Ag NPs in contact with food simulants simulating long-term storage with aqueous and fatty food contact has been systematically studied. ICP-MS showed that detectable migration of total silver was found only in aqueous food simulants. Further, stability using asymmetric flow field-flow fractionation (AF4) analysis revealed rapid oxidative dissolution of the Ag NPs and presence of silver ions in the migration solution. Silver was not detected in both isooctane and 95% ethanol indicating that Ag NPs did not migrate. Migration modeling showed that nanomaterials get immobilized in a polymeric matrix, and those smaller than 3–4 nm in diameter have less migration potential (Bott et al. 2014a).
Engineered nanomaterials in the environment: Are they safe?
Published in Critical Reviews in Environmental Science and Technology, 2021
Jian Zhao, Meiqi Lin, Zhenyu Wang, Xuesong Cao, Baoshan Xing
The released NMs in the environment were first detected by transmission electron microscopy/energy dispersive X-ray analysis (TEM/EDX) and inductively coupled plasma-mass spectrometry (ICP-MS) (Kägi et al., 2008). Currently, electrothermal atomic absorption spectrometry (ET-AAS) (Li et al., 2016), asymmetric-flow field flow fractionation with inductively coupled plasma–mass spectrometry (AF4-ICP-MS) (Hoque et al., 2012), and especially, single particle inductively coupled plasma-mass spectrometry (sp-ICP-MS) (Loula et al., 2019; Peters et al., 2018; Wu et al., 2020; Xiao et al., 2019) have been developed for characterization and quantification of NMs in natural environments. Figure 3 summarized the MECs of NMs in surface water, and sediment based on the published data (Table S2).
Advances in self-crosslinking of acrylic emulsion: what we know and what we would like to know
Published in Journal of Dispersion Science and Technology, 2019
Sumit Parvate, Prakash Mahanwar
The team of Machotova incorporated keto-hydrazine crosslinking concept in the field of the acrylic microgel. They determined the molar mass of structured emulsion microgels by means of size exclusion chromatography with a multi-angle light scattering (SEC-MALS) and asymmetric flow field flow fractionation with multi-angle light scattering (A4F- MALS) analytical systems. As from analysis, they claimed that, the decrease in molar mass of shell copolymers resulted in the reduction of minimum film-forming temperature (MFFT), hardness, stress-strain properties and solvent resistance of the emulsion film.[86,87]
The toxicity of non-aged and aged coated silver nanoparticles to the freshwater shrimp Paratya australiensis
Published in Journal of Toxicology and Environmental Health, Part A, 2019
Sam Lekamge, Ana F. Miranda, Ben Pham, Andrew S. Ball, Ravi Shukla, Dayanthi Nugegoda
The absorbance peaks of T-AgNPs and E-AgNPs decreased by 32 and 28% within 24 hr, respectively while it was only ~6% for C-AgNPs (Figure 5a–c). The fall in the absorbance peak together with the broadening of SPR spectra was reported to be due to the aggregation or dissolution of NPs (Jiménez-Lamana and Slaveykova 2016). Tejamaya et al. (2012) observed a broadening of SPR peaks of PEG and polyvinyl pyrrolidone (PVP) coated AgNPs, with a broader size distribution, as confirmed by higher Pdi from dynamic light scattering (DLS) results. Similarly, Jiménez-Lamana and Slaveykova (2016) found a broadening of SPR curves with agglomeration of citrate, PVP and lipoic acid coated AgNPs. The peaks of T-AgNPs and E-AgNPs were further reduced, and SPR bands broadened; new absorbance peaks appeared at longer wavelengths which were not detected for C-AgNPs. New absorbance peaks are due to scattered light from large aggregates (Jiménez-Lamana and Slaveykova 2016; Stebounova, Guio, and Grassian 2011; Tejamaya et al. 2012). Evidence indicates that curcumin provides the most protective effect as a coating agent compared with tyrosine and EGCG while SPR curves revealed that all three coated AgNPs showed the presence of AgNPs after 32 days. Interestingly, the SPR bands of AgNPs in shrimp medium over time did not fully agree with the values obtained for HDD and zeta potential. The absorbance peaks of both T-AgNPs and E-AgNPs continuously fell and the SPR bands broadened, although the zeta potential was quite stable after 24 hr while the DLS results demonstrated that the HDD of T-AgNPs did not change significantly. Similarly Jiménez-Lamana and Slaveykova (2016) for PVP coated AgNPs noted the absorbance peak reduced in different media over time, but the size of the NPs, measured with asymmetric flow field-flow fractionation (AsFIFFF) did not change. Jiménez-Lamana and Slaveykova (2016) suggested dissolution as the possible source for the absorbance reduction. Further, it was noted that the lipoic acid coated AgNPs presented SPR after 168 hr but no signal was detected for size measurements. It was not clear which type of transformation NPs have undergone. Jiménez-Lamana and Slaveykova (2016) suggested possible agglomeration with time. The lack of sensitivity in the techniques used also represents a limitation to the accurate discrimination of the stability of different NPs. Tejamaya et al. (2012) observed less apparent trends in the size of AgNPs in different media over time. This was attributed to the lack of sensitivity and accuracy of DLS in aggregated NP suspensions. Further specific research is required to fully address the effects of these coatings on the stability of AgNPs in shrimp media. The SPR bands of AgNPs did not change in MilliQ water (Figure. S4).