Hydrodynamic Diameter Of Nanoparticles Research Articles

Effect of L- or D,L-leucine content on self-assembly and properties of its amphiphilic copolymers with L-lysine

Copolymers of l-lysine and l/d,l-leucine differing in amino acid composition were synthesized and characterized for their self-assembly into nanoparticles. The effect of polypeptide composition on critical aggregation concentration, hydrodynamic diameter of nanoparticles, their stability and cytotoxicity was explored and discussed.

Combination nanochemotherapy of brain tumor using polymeric nanoparticles loaded with doxorubicin and paclitaxel: An in vitro and in vivo study

This study aims to overcome physiological barriers and increase the therapeutic index for the treatment of glioblastoma (GBM) tumors by using Paclitaxel (PTX) loaded Poly(lactic co-glycolic acid) nanoparticles (PTX-PLGA-NPs) and Doxorubicin (DOX) loaded Poly (lactic co-glycolic acid) nanoparticles (DOX-PLGA-NPs). The hydrodynamic diameter of nanoparticles (NPs) was characterized by dynamic light scattering (DLS) which was 94 ± 4 nm and 133 ± 6 nm for DOX-PLGA-NPs, and PTX-PLGA-NPs, respectively. The zeta potential for DOX-PLGA-NPs and PTX-PLGA-NPs were −15.2 ± 0.18 mV and −17.3 ± 0.34 mV, respectively. The cytotoxicity of PTX-PLGA-NPs and DOX-PLGA-NPs was augmented compared to DOX and PTX on C6 GBM cells. The Lactate dehydrogenase (LDH) tests for various formulations were carried out. The results indicated that the amount of released LDH was 262 ± 7.84 U.L-1 at the concentration of 2 mg/mL in the combination therapy, which was much higher than other groups (DOX-PLGA-NPs (210 ± 6.92 U.L-1), PTX-PLGA-NPs (201 ± 8.65 U.L-1), DOX (110 ± 9.81 U.L-1), PTX (95 ± 5.02 U.L-1) and PTX + DOX (67 ± 4.89 U.L-1)). MRI results of the combination therapy of PTX-PLGA-NPs and DOX-PLGA-NPs indicated that GBM tumor size decreased considerably compared to the other formulations. Also, combination therapy of PTX-PLGA-NPs and DOX-PLGA-NPs demonstrated a longer median survival of more than 80 days compared to PTX (38 days), DOX (37 days) and PTX + DOX (48 days), PTX-NPs (58 days) and DOX-NPs (62 days). The results of locomotion, body weight, rearing and grooming assays indicated that combination therapy of PTX-PLGA-NPs and DOX-PLGA-NPs had the most positive effect on the movements of rats compared to the other formulations.

Transcriptome analysis of some genes of Staphylococcus aureus exposed to alkylated, nano- and native chitosans

Chitosan, including native, N- alkyl (AlkCs), and nanoparticles chitosan (CsNPs), were prepared and characterized. Average size and hydrodynamic diameter of nanoparticles were determined at 126 nm and 240 nm with a polydispersity index (PDI) of 0.154 and zeta potential of 30 mV, respectively. Crystallinity index for Cs, AlkCs, and CsNPs was calculated as 57.85, 30.24, and 24.85, respectively. Minimum concentration of growth inhibition (125.78 µg/ml) and lethality (100 µg/ml) was observed for CsNPs (P < 0.05). CsNPs and AlkCs showed the highest diameter of the growth inhibition zone at 1250 μg/mL concentration, respectively (P < 0.05). Membrane permeability test, the highest absorption of ortho-nitrophenol was observed after 90 min with 0.11 nm. The most significant decrease in absorption in chitosan was observed at the end of 120 min. DAPI (4′,6-Diamidino-2-Phenylindole) staining test showed higher cell death of bacteria treated with AlkCs and CsNPs. Images obtained from atomic force microscopy (AFM) showed a change in the morphology of the treated cells compared to the spherical and clustered control cells. A significant increase in the expression of vraS, vraR, lytM, lrgA and lrgB genes was observed as a result of induction of S. aureus cell wall by Cs, AlkCs and CsNPs, d.

Averaging Strategy for Interpretable Machine Learning on Small Datasets to Understand Element Uptake after Seed Nanotreatment.

Understanding plant uptake and translocation of nanomaterials is crucial for ensuring the successful and sustainable applications of seed nanotreatment. Here, we collect a dataset with 280 instances from experiments for predicting the relative metal/metalloid concentration (RMC) in maize seedlings after seed priming by various metal and metalloid oxide nanoparticles. To obtain unbiased predictions and explanations on small datasets, we present an averaging strategy and add a dimension for interpretable machine learning. The findings in post-hoc interpretations of sophisticated LightGBM models demonstrate that solubility is highly correlated with model performance. Surface area, concentration, zeta potential, and hydrodynamic diameter of nanoparticles and seedling part and relative weight of plants are dominant factors affecting RMC, and their effects and interactions are explained. Furthermore, self-interpretable models using the RuleFit algorithm are established to successfully predict RMC only based on six important features identified by post-hoc explanations. We then develop a visualization tool called RuleGrid to depict feature effects and interactions in numerous generated rules. Consistent parameter-RMC relationships are obtained by different methods. This study offers a promising interpretable data-driven approach to expand the knowledge of nanoparticle fate in plants and may profoundly contribute to the safety-by-design of nanomaterials in agricultural and environmental applications.

Role of surface hydrophilicity on MR relaxivity of PEG coated- gadolinium oxide nanoparticles

The magnetic resonance (MR) contrast enhancement capabilities of gadolinium oxide nanoparticles (GONPs) have high dependency on its surface chemistry- as the solution properties such as colloidal stability and hydrodynamic diameter of nanoparticles which are prime regulatory parameter for MR relaxivity, are all governed by grafting density of surface material. However, the purification of synthesized surface coated nanoparticles, without compromising the surface properties, remains a major challenge. Among the various cleaning methods, dialysis is often used to remove the unwanted by-products produced during synthesis. However, the effect of dialysis time may significantly impact the surface properties and hence, the MR contrast properties of such nano-formulations. The aim of the present study is to evaluate the effect of dialysis time on surface chemistry and MR contrast enhancement properties of GONPs by comparing the proton relaxivity data. Ultra-small polyethylene glycol (PEG)-coated GONPs with an average particle diameter of 17 nm were synthesized using polyol method. The impact of dialysis time has been investigated systematically on the size distribution, hydrophilicity, magnetic properties, polymer grafting density and relaxometric properties of the as synthesized GONPs. A significant impact of dialysis time was observed on surface chemistry and hence, on the MR relaxivity of synthesized NPs. We evidenced a dramatic decrease in the proton relaxivities of GONPs with increase in dialysis time, which correlated well with the observed decrease in the grafting density of surface polymer. The results clearly indicate that the proton relaxivity of GONPs of similar size and same coating material depends on the surface coating thickness and hydrophilicity of the coating polymer. Overall, it is essential to optimize the accurate time duration of dialysis treatment as the prolonged dialysis may have negative effect on the relaxation times and hence on MR contrast enhancement properties of GONPs. This study is a strategic pathway to fine-tune the dialysis treatment of as-synthesized surface-capped GONPs for pre-eminent MR contrast imaging.

Synthesis and Application of Albumin Nanoparticles Loaded with Prussian Blue Nanozymes

Prussian blue nanozymes exhibit peroxidase-like catalytic activity and are therefore considered a stable and inexpensive alternative to natural peroxidases in the enzyme-linked immunosorbent assay (ELISA). In this work, we propose a robust method of Prussian blue nanozyme functionalization, which relies on the entrapment of nanozymes into albumin nanoparticles. The principle of the method is the addition of ethanol to a solution that contains albumin and nanozymes. At a high ethanol concentration solubility of albumin decreases, resulting in the formation of albumin nanoparticles loaded with nanozymes. The hydrodynamic diameter of nanoparticles was between 120 and 230 nm and depended on the nanozyme-to-BSA ratio. Encapsulation efficiency of nanozymes reached 96–99% and up to 190 μg of nanozymes were loaded per 1 mg of nanoparticles. Nanoparticles were stable at pH 5.5–7.5 and upon long-term storage in deionized water. Excellent reproducibility of the synthesis procedure was confirmed by the preparation of three individual batches of Prussian-blue-loaded BSA nanoparticles with almost identical properties. Nanoparticles were functionalized with monoclonal antibodies using glutaraldehyde cross-linking. The resulting conjugates were applied as labels in an ELISA-like assay of tumor marker prostate-specific antigen (PSA). The lower limit of detection was below 1 ng/mL, which enables measurement of PSA in the range of clinically relevant concentrations.

Magnetic assisted synthesis of ZnO nanoparticle by electrochemical discharge method

Metal oxide optoelectronics nanoparticles are widely used in industries. Many efforts were made to form uniform and pure metal oxide Nanoparticles. This paper focused on synthesizing simple step nanoflower like ZnO structure in atmospheric conditions. The Electrochemical discharge method is used to synthesize ZnO nanoparticles in NaOH electrolyte medium. The effect of electrolyte rotation on morphology was analyzed at 200 rpm resulted uniform flower shape of nanoparticles, confirmed by FESEM images. The XRD results reveal that the pure crystalline phase of nanoparticles obtained has the average crystalline size of 29 nm. The uniform voltage and current wave form was also observed at 200 rpm rotation of electrolyte. The chemical composition of the element was studied by EDS analysis to confirm the presence of zinc and oxygen element. DLS result gives the hydrodynamic diameter of nanoparticles within the range of 100 nm.

Effect of Nanoparticle Size and Natural Organic Matter Composition on the Bioavailability of Polyvinylpyrrolidone-Coated Platinum Nanoparticles to a Model Freshwater Invertebrate.

The bioavailability of dissolved Pt(IV) and polyvinylpyrrolidone-coated platinum nanoparticles (PtNPs) of five different nominal hydrodynamic diameters (20, 30, 50, 75, and 95 nm) was characterized in laboratory experiments using the model freshwater snail Lymnaea stagnalis. Dissolved Pt(IV) and all nanoparticle sizes were bioavailable to L. stagnalis. Platinum bioavailability, inferred from conditional uptake rate constants, was greater for nanoparticulate than dissolved forms and increased with increasing nanoparticle hydrodynamic diameter. The effect of natural organic matter (NOM) composition on PtNP bioavailability was evaluated using six NOM samples at two nanoparticle sizes (20 and 95 nm). NOM suppressed the bioavailability of 95 nm PtNPs in all cases, and DOM reduced sulfur content exhibited a positive correlation with 95 nm PtNP bioavailability. The bioavailability of 20 nm PtNPs was only suppressed by NOM with a low reduced sulfur content. The physiological elimination of Pt accumulated after dissolved Pt(IV) exposure was slow and constant. In contrast, the elimination of Pt accumulated after PtNP exposures exhibited a triphasic pattern likely involving in vivo PtNP dissolution. This work highlights the importance of PtNP size and interfacial interactions with NOM on Pt bioavailability and suggests that in vivo PtNP transformations could yield unexpectedly higher adverse effects to organisms than dissolved exposure alone.

Synthesis and magnetic hyperthermia properties of zwitterionic dopamine sulfonate ligated magnesium ferrite and zinc ferrite nanoparticles

$${\text{MgFe}_{2}\text {O}_{4}}$$ and $$\text {ZnFe}_{2}\text {O}_{4}$$ nanoparticles have shown relatively good biocompatibility and high superparamagnetic hyperthermia value, on par with the well-studied $$\text {Fe}_{3}\text {O}_{4}$$ nanoparticles. However, different studies have reported different values of hyperthermia on both the compounds. To elucidate which compound is superior hyperthermia compound, well-crystallined and narrow size distributed $$\text {MgFe}_{2}\text {O}_{4}$$ and $$Z\text {nFe}_{2}\text {O}_{4}$$ spherical nanoparticles (16 nm diameter) were synthesized by solvothermal reflux method and studied their magnetic hyperthermia values under identical conditions. To further enhance superparamagnetic hyperthermia in $$\text {MgFe}_{2}\text {O}_{4}$$ and $$\text {ZnFe}_{2}\text {O}_{4}$$ nanoparticles, hydrodynamic diameter of nanoparticles were reduced by completely removing the long chain oleic acid surfactant monolayer on nanoparticles and ligated short chain zwitterionic dopamine sulfonate surfactant on bare nanoparticles. These nanoparticles show good aqueous colloidal stability with zeta potential of − 32 mV. The study reveals that $$\text {MgFe}_{2}\text {O}_{4}$$ nanoparticles shows higher hyperthermia value (265 W/g) than that (216 W/g) of $$\text {ZnFe}_{2}\text {O}_{4}$$ nanoparticles at 1 mg/mL concentration under 35.33 kA/m and 316 kHz field parameters. This is high value at 1 mg/mL concentration compared to literature. High hyperthermia value arises from higher saturation mass magnetization (45.5 emu/g) of $$\text {MgFe}_{2}\text {O}_{4}$$ than that (36.5 emu/g) of $$\text {ZnFe}_{2}\text {O}_{4}$$ nanoparticles. High saturation magnetization of $$\text {MgFe}_{2}\text {O}_{4}$$ results from the preferential tetrahedral sites occupation of nonmagnetic $${\text {Mg}^{2+}}$$ due to small ionic radii than $${\text {Zn}^{2+}}$$ ions. If tetrahedral magnetic sublattice is occupied by more nonmagnetic cations, the net ferrimagnetic moment increases. The samples were characterized by X-ray diffraction, infrared spectra, thermogravimetry analysis, differential scanning calorimetry, field emission scanning electron microscope, zeta potential, vibrating sample magnetometer, calorimetric hyperthermia methods.

Experimental and numerical studies on microfluidic preparation and engineering of chitosan nanoparticles

Optimization of nanoparticle (NP) characteristics (e.g. size, shape, zeta potential, etc.) is essential to achieve desirable cell responses. In the current study, we intend to introduce an equation representing a prediction about hydrodynamic diameter of microfluidic (MF) preparation of chitosan-tripolyphosphate (CS-TPP) NPs as an influential factor on cell behavior. Both numerical simulation and experimental study have been employed for this study. TPP concentration, channel length and flow ratio (lateral flow to core flow) to find optimum mixing efficiency conditions using a computational fluid dynamics (CFD) in COMSOL 5.5 in a t-shaped MFD were evaluated numerically and consequently in experimental section, a cross-junction MFD was used for preparation of CS-TPP NPs based on optimum conditions obtained from numerical section to find a correlation between NPs hydrodynamic diameter, flow ratios and TPP concentrations.

Hydrodynamic Diameter of Silver Nanoparticles in Solutions of Nonionic Surfactants

Physicochemical characteristics of silver nanoparticles with known sizes are studied, depending on the concentration of nonionic surfactants and the concentration of the metal. Surfactants are used that form micelles of different sizes and different intensities of light scattering. It is shown that the surface tension and adhesion properties of solutions of nonionic surfactants are determined by the solvent in ranges of concentration lower than 1 mol/L. An approach based on spectrophotometry and viscosimetry is proposed that allows determination of the most likely reasons for discrepancies in the hydrodynamic diameter of nanoparticles in solutions of nonionic surfactants and the actual diameter of the nanoparticles.

Accurate Measurement of Self-diffusion Coefficient of Nanoparticles in Aqueous Solutions Using a Dynamic Light Scattering

One of the standard methods used to measure the hydrodynamic diameter of nanoparticles is photon correlation spectroscopy, especially dynamic light scattering (DLS). In principle, this technique is to analyze correlation function of the scattered light from the nanoparticles undergoing Brownian motion in solution and to calculate the diffusion coefficient from the correlation function which is converted into the hydrodynamic diameter. However, when using this technique, one needs to pay careful attention to interaction effects (i.e., particle-particle and particle-solvent interactions) on the diffusion coefficient of the particles in solution. If not, then incorrect information can be obtained on the self-diffusion coefficients of nanoparticles. In order to facilitate a strict procedure for obtaining real size of the nanoparticles in solution, we used 20 nm, 50 nm and 100 nm-nominal polystyrene latex (PSL) nanoparticle solutions for DLS measurement. We represented that a rigorous scrutinizing the concentration dependence of the diffusion coefficient of the PSL nanoparticles made it possible to separate the interaction effect from the diffusion phenomena of the PSL nanoparticles suspended in water and to give real size of the PSL nanoparticles.

Ultrasonication Mediated Fabrication of Glycine Coated Gadolinium Oxide Nanoparticles as MRI Contrast Agents

Gadolinium oxide nanoparticles (Gd2O3NPs) have recently gained significant interest because of their broad range of applications in biomedicine. Nevertheless, their functionality with amino acids was not clearly described. In the current study, the capability of sonication method in the Gd2O3NPs synthesis was explored for the first time. The process of sonication is a very effective technique for fabricating nanoparticles (NPs) which can uniformly disperse in liquids and hence this report describes the utilization of ultra-sonication method for the synthesis of uniform sized (25 nm) Gd2O3NPs coated with Glycine. Fourier transform- Infrared (FT-IR) spectroscopy and dynamic light scattering (DLS) studies were used for confirming the evaluation of Glycine conjugation with NPs. Plasma stability studies clearly showed that, as the time period of incubation increases, the hydrodynamic diameter of NPs in Glycine-Gd2O3 raises slightly to 40 ± 13 nm from 35.24 ± 1.6 nm in the initial stage. Furthermore, the relaxation time, T1 at various time points (1, 2, 4, 6, 9 and 24 h) during the incubation was determined and these values confirmed the excellent stability of Glycine-Gd2O3NPs MRI signal present in plasma.

Silicon nanoparticles with iron impurities for multifunctional applications

Crystalline silicon (Si) nanoparticles (NPs) doped with iron (Fe) in the range from 0.02 to 2.5 at.% were prepared by plasma-ablative synthesis and were investigated by means of the transmission electron microscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), infrared spectroscopy and nuclear magnetic resonance relaxometry. While the nanocrystal size in Si:Fe NPs did not depend significantly on Fe content, the hydrodynamic diameter of NPs in aqueous suspensions increases from 50 to 180[Formula: see text]nm. Both the transverse and longitudinal proton relaxation time were found to decrease in the prepared suspensions of Si:Fe NPs. Maximal shortening of the transverse relaxion was observed for Si:Fe NPs with 0.2 at.% of Fe and the relaxation rate was almost linearly proportional to the NP concentration. Both these findings and in vivo tests indicate that Si:Fe NPs are promising for biomedical applications in magnetic resonance imaging (MRI) and therapy of cancer.

Synthesis and Electrophoretic Concentration of Ag–Cu Nanoparticles of the Core–Shell Type in an AOT Microemulsion in n-Decane

Stable organosols of silver and copper bimetallic nanoparticles were obtained in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles in the emulsion and microemulsion variants and characterized by physicochemical methods. The adsorption layer of nanoparticles in AOT solutions in n-decane was found to have a complex multilayer structure; an increase in the mole fraction of copper led to an increase in the hydrodynamic diameter of nanoparticles from 14 to 23 nm and a decrease in the electrokinetic potential from 18 to 7 mV. The surface charge of nanoparticles can be increased by diluting the sols with chloroform, and electrophoretic concentration can be performed with concentration factors of 30–50 depending on the composition. Based on the XRD data for solid composites in AOT, it was concluded that the structure of nanoparticles is most likely of the “core–shell” type with a silver metal core and a surface layer of X-ray amorphous copper.

Phytosynthesis of Au and Au/ZrO₂ bi-Phasic System Nanoparticles with Evaluation of Their Colloidal Stability.

Due to its easy availability, preparation, handling and non-toxic nature, Equisetum arvense horsetail extract was chosen as a reducing, stabilizing and functionalizing agent for Au and bi-phasic Au/ZrO₂ nanoparticle phytosynthesis-inorganic nanoparticle synthesis mediated by plant extract. We studied Au and bi-phasic Au/ZrO₂ nanoparticles in colloids by various physical-chemical and analytical methods over 5 weeks. Dynamic Light Scattering and Scanning Transmission Electron Microscopy compared core and hydrodynamic diameters of nanoparticles. ζ-potential measurement indirectly determined nanoparticles stability in liquid medium. Ultraviolet-Visible Spectroscopy characterized basic absorbance maxima for both Au and the bi-phasic Au/ZrO₂ system. Finally, total metal concentration was determined using Inductively Coupled Plasma Mass Spectrometry. ζ-potential measurements proved satisfactory stability of both Au (-13.4 to -17 mV) and Au/ZrO₂ nanoparticles (-14.1 to -17.5 mV) over the experimental period. Scanning Transmission Electron Microscopy with Selected Area Diffraction analysis confirmed nanoparticles crystalline nature, and we determined 24 nm and 40 nm core nanogold diameters in Au and Au/ZrO₂ nanoparticle colloids. Dynamic light scattering analysis confirmed the dichotomy between particle sizes in liquid medium in the hundreds of nanometers measured, and long-term measurements confirmed reasonable colloid stability-a paramount parameter for potential nanoparticles applications; especially in heterogeneous catalysis.

Self-assembled nanoparticles from heat treated ovalbumin as nanocarriers for polyunsaturated fatty acids

The objective of the present work was to obtain and characterize two heat induced (85 °C, 5 min) ovalbumin nanoparticles (OVAn1 formed at pH 11.35 and OVAn2 formed at pH 7.50). In addition, the impact of these OVA nanosized aggregates on the formation and characterization of inclusion nanocomplexes formed with two polyunsaturated fatty acids (PUFAs): linoleic acid (LA) and its isomer, conjugated linoleic acid (CLA) was studied. The pH in which heat treatment was performed had a great impact on nanoparticles hydrodynamic diameter (dH). Nanoparticles dH values were 24.63 ± 0.04 nm for OVAn1 and 92.0 ± 0.2 nm for OVAn2, respectively, and no significant differences in ζ potential values (p > 0.05) were detected. Nanocomplexes colloidal characteristics were studied by particle size distribution (PSD) and ζ potential determinations. In all cases, size measurements showed that PUFAs binding promoted an increased nanoparticles size. In addition, atomic force microscopy (AFM) examination for nanoparticles and nanocomplexes showed a rounded shape and an increase in dimensions of the nanocomplexes which was attributed to LA and CLA binding. On the other hand, nanocomplex formation was monitored by intrinsic and extrinsic fluorescence spectroscopy. Results highlighted that both nanoparticles bound LA and CLA in greater amount than OVA did. Besides, both nanoparticles were able to bind more amount of LA than CLA. Results suggested that knowledge of differences in OVA nanoparticles properties and PUFAs molecular structure is a relevant requisite for the design of inclusion nanocomplexes with especial colloidal properties.

Synthesis of gold organometallics at the nanoscale

We report the synthesis of aryldiazonium tetrachloroaurate(III) salts [X-4-C6H4N≡N]AuCl4 (X = F, Cl, Br, I, CN, NO2) and their mild reduction to covalently functionalized nanoparticles. The synthesis of the salts was carried out by the oxidation of anilines, dissolved in HCl, using sodium nitrite followed by the exchange of the counter anion with [AuCl4]- in water. In another procedure, the anilines were protonated with H[AuCl4] in acetonitrile followed by one-electron oxidation using nitrosonium salt [NO]X (X = BF4−, PF6−). Raman and ATR-FTIR spectroscopy displayed the diazonium νN≡N and Raman showed the tetrachloroaurate νAu-Cl stretching frequencies. X-ray crystal structure of [NO2-4-C6H4N≡N]AuCl4 salt showed N≡N bond distance typical of a triple bond. Gold-aryl nanoparticles were constructed by the mild chemical reduction of the diazonium gold(III) salts using 9-borabicyclo[3.3.1]nonane (9-BBN). Nanoparticles hydrodynamic diameter, elemental composition, dynamics information, and stability data were determined. Transmission electron microscopy (TEM) measurements showed limited aggregation due to the small suppressing organic shell. However, dynamic light scattering (DLS) measurements showed considerable aggregation in acetonitrile. X-ray photoelectron spectrometry (XPS) showed the gold core in zero oxidation state and manifested the gold-organic shell connectivity. The –N=N-aryl interfacial formation on the gold surface can be ruled out since the N1s peak assigned to the diazonium moiety showed no sign in the XPS nitrogen area in addition to its absence in the ATR-FTIR spectra. Raman spectroscopy measurements showed a peak assigned to gold-carbon bonding supported by density functional calculations (DFT) on Au20-C6H4-CN model.

Physical characterization and in vivo organ distribution of coated iron oxide nanoparticles

Citrate-stabilized iron oxide magnetic nanoparticles (MNPs) were coated with one of carboxymethyl dextran (CM-dextran), polyethylene glycol-polyethylene imine (PEG-PEI), methoxy-PEG-phosphate+rutin, or dextran. They were characterized for size, zeta potential, hysteresis heating in an alternating magnetic field, dynamic magnetic susceptibility, and examined for their distribution in mouse organs following intravenous delivery. Except for PEG-PEI-coated nanoparticles, all coated nanoparticles had a negative zeta potential at physiological pH. Nanoparticle sizing by dynamic light scattering revealed an increased nanoparticle hydrodynamic diameter upon coating. Magnetic hysteresis heating changed little with coating; however, the larger particles demonstrated significant shifts of the peak of complex magnetic susceptibility to lower frequency. 48 hours following intravenous injection of nanoparticles, mice were sacrificed and tissues were collected to measure iron concentration. Iron deposition from nanoparticles possessing a negative surface potential was observed to have highest accumulation in livers and spleens. In contrast, iron deposition from positively charged PEG-PEI-coated nanoparticles was observed to have highest concentration in lungs. These preliminary results suggest a complex interplay between nanoparticle size and charge determines organ distribution of systemically-delivered iron oxide magnetic nanoparticles.

Biotoxicity of TiO₂ Nanoparticles on Raphidocelis subcapitata Microalgae Exemplified by Membrane Deformation.

TiO2 nanoparticles (NPs), which are mainly used in consumer products (mostly cosmetics), have been found to cause ecotoxic effects in the aquatic environment. The green algae Raphidocelis subcapitata, as a representative of primary producers of the freshwater ecosystem, has been frequently used to study the effects of metal oxide NPs. An ecotoxicity study was conducted herein to investigate the effects of TiO2 NPs on survival and membrane deformation of algal cells. Five different concentrations of nano-TiO2 particles (1, 10, 50, 100 and 500 mg/L) were prepared in synthetic surface water samples with five different water quality characteristics (pH 6.4–8.4, hardness 10–320 mg CaCO3/L, ionic strength 0.2–8 mM, and alkalinity 10–245 mg CaCO3/L). Results showed a significant increase in the hydrodynamic diameter of NPs with respect to both NP concentrations and ionic content of the test system. A soft synthetic freshwater system at pH 7.3 ± 0.2 appeared to provide the most effective water type, with more than 95% algal mortality observed at 50, 100 and 500 mg/L NP concentrations. At high exposure concentrations, increased malondialdehyde formations were observed. Moreover, due to membrane deformation, TEM images correlated the uptake of the NPs.