Synthesis of Precision Gold Nanoparticles Using Turkevich Method.

Gold nanoparticles (AuNPs) exhibit unique size-dependent physiochemical properties that make them attractive for a wide range of applications. However, the large-scale availability of precision AuNPs has been minimal. Not only must the required nanoparticles be of precise size and morphology, but they must also be of exceedingly narrow size distribution to yield accurate and reliable performance. The present study aims to synthesize precision AuNPs and to assess the advantages and limitations of the Turkevich method-one of the common chemical synthesis technique. Colloidal AuNPs from 15 nm to 50 nm in diameter were synthesized using the Turkevich method. The effect of the molar ratio of the reagent mixture (trisodium citrate to gold chloride), the scaled-up batch size, the initial gold chloride concentration, and the reaction temperature was studied. The morphology, optical property, surface chemistry, and chemical composition of AuNPs were thoroughly characterized. It was determined that the as-synthesized AuNPs between 15 nm and 30 nm exhibit well-defined size and shape, and narrow size distribution (PDI < 0.20). However, the AuNPs became more polydispersed and less spherical in shape as the particle size increased.

Engineered metal oxide nanomaterials inhibit corneal epithelial wound healing in vitro and in vivo.

Ocular exposure to metal oxide engineered nanomaterials (ENMs) is common as exemplified by zinc oxide (ZnO), a major constituent of sunscreens and cosmetics. The ocular surface that includes the transparent cornea and its protective tear film are common sites of exposure for metal ENMs. Despite the frequency of exposure of the ocular surface, there is a knowledge gap regarding the effects of metal oxide ENMs on the cornea in health and disease. Therefore, we studied the effects of metal oxide ENMs on the cornea in the presence or absence of injury. Cell viability of immortalized human corneal epithelial (hTCEpi) cells was assessed following treatment with 11 metal oxide ENMs with a concentration ranging from 0.5 to 250 µg/mL for 24 hours. An epithelial wound healing assay with a monolayer of hTCEpi cells was then performed using 11 metal oxide ENMs at select concentrations based on data from the viability assays. Subsequently, based on the in vitro results, in vivo testing of precorneal tear film (PTF) quantity and stability as well as a corneal epithelial wound healing were tested in the presence or absence ZnO or vanadium pentoxide (V2O5) at a concentration of 50 µg/mL. We found that WO3, ZnO, V2O5 and CuO ENMs significantly reduced hTCEpi cell viability in comparison to vehicle control or the other metal oxide ENMs tested. Furthermore, ZnO and V2O5 ENMs also significantly decreased hTCEpi cell migration. Although ZnO and V2O5 did not alter PTF parameters of rabbits in vivo, corneal epithelial wound healing was significantly delayed by topical ZnO while V2O5 did not alter wound healing. Finally, hyperspectral images confirmed penetration of ZnO and V2O5 through all corneal layers and into the iris stroma. Considering the marked epithelial toxicity and corneal penetration of ZnO, further investigations on the impact of this ENM on the eye are warranted.

Development & Characterization of Fluorescently Tagged Nanocellulose for Nanotoxicological Studies.

The rapid adoption of nanocellulose-based engineered nanomaterials (CNM) by many industries generates environmental health and safety (EHS) concerns. This work presents the development of fluorescently tagged CNM which can be used to study their interactions with biological systems. Specifically, cellulose nano-fibrils and cellulose nano-crystals with covalently attached fluorescein isothiocyanate (FITC) molecules on their surface were synthesized. The fluorescence of the FITC-tagged materials was assessed along with potential FITC detachment under pH conditions encountered in the human gastrointestinal tract, in intracellular compartments, and in cell culture media. Finally, the potential cytotoxicity due to the presence of FITC molecules on the surface of CNM was assessed using a cellular gut epithelium model. The results showed that neither FITC-CNF nor FITC-CNC were cytotoxic and that they have a comparable bioactivity to their untagged counterparts, rendering them suitable for biological studies.

Safer-by-design flame-sprayed silicon dioxide nanoparticles: the role of silanol content on ROS generation, surface activity and cytotoxicity.

BACKGROUND: Amorphous silica nanoparticles (SiO2 NPs) have been regarded as relatively benign nanomaterials, however, this widely held opinion has been questioned in recent years by several reports on in vitro and in vivo toxicity. Surface chemistry, more specifically the surface silanol content, has been identified as an important toxicity modulator for SiO2 NPs. Here, quantitative relationships between the silanol content on SiO2 NPs, free radical generation and toxicity have been identified, with the purpose of synthesizing safer-by-design fumed silica nanoparticles. RESULTS: Consistent and statistically significant trends were seen between the total silanol content, cell membrane damage, and cell viability, but not with intracellular reactive oxygen species (ROS), in the macrophages RAW264.7. SiO2 NPs with lower total silanol content exhibited larger adverse cellular effects. The SAEC epithelial cell line did not show any sign of toxicity by any of the nanoparticles. Free radical generation and surface reactivity of these nanoparticles were also influenced by the temperature of combustion and total silanol content. CONCLUSION: Surface silanol content plays an important role in cellular toxicity and surface reactivity, although it might not be the sole factor influencing fumed silica NP toxicity. It was demonstrated that synthesis conditions for SiO2 NPs influence the type and quantity of free radicals, oxidative stress, nanoparticle interaction with the biological milieu they come in contact with, and determine the specific mechanisms of toxicity. We demonstrate here that it is possible to produce much less toxic fumed silicas by modulating the synthesis conditions.

Age-Dependent Translocation of Gold Nanoparticles across the Air-Blood Barrier.

Do immature lungs have air-blood barriers that are more permeable to inhaled nanoparticles than those of fully developed mature lungs? Data supporting this notion and explaining the underlying mechanisms do not exist as far as we know. Using a rat model of postnatal lung development, here the data exactly supporting this notion, that is, significantly more gold nanoparticles (NPs) cross from the air space of the lungs to the rest of the body in neonates than in adults, are presented. Moreover, in neonates the translocation of gold NPs is not size dependent, whereas in adult animals smaller NPs cross the air-blood lung barrier much more efficiently than larger NPs. This difference in air-blood permeability in neonate versus adult animals suggests that NP translocation in the immature lungs may follow different rules than in mature lungs. Supporting this notion, we propose that the paracellular transport route may play a more significant role in NP translocation in immature animals, as suggested by protein expression studies. Findings from this study are critical to design optimal ways of inhalation drug delivery using NP nanocarriers for this age group, as well as for better understanding of the potential adverse health effects of nanoparticle exposures in infants and young children.

Inactivation of common hospital acquired pathogens on surfaces and in air utilizing engineered water nanostructures (EWNS) based nano-sanitizers.

Infectious diseases represent a major public health challenge worldwide. There are various modes for the transmission of these diseases, with surface and airborne transmission being two of the most important ones. The inefficiencies of current intervention methods have resulted in the emergence of nosocomial infections. Here, we report the use of a nanotechnology based antimicrobial platform using Engineered Water Nanostructures (EWNS) generated using a combined electrospray and ionization of an aqueous suspension of various active ingredients (AIs). These EWNS based nano-sanitizers were tested in terms of their ability to efficiently deliver AI and inactivate Acinetobacter baumannii and influenza H1N1/PR/8 on both surfaces and air. Results indicate a significant reduction in the concertation of the pathogens, while the delivered to pathogen AI doses required for inactivation were miniscule (nanogram level), indicating the viability of such nano-carrier platform as an intervention technology against infectious microorganisms.

Scatter Enhanced Phase Contrast Microscopy for Discriminating Mechanisms of Active Nanoparticle Transport in Living Cells.

Understanding the uptake and transport dynamics of engineered nanomaterials (ENMs) by mammalian cells is an important step in designing next-generation drug delivery systems. However, to track these materials and their cellular interactions, current studies often depend on surface-bound fluorescent labels, which have the potential to alter native cellular recognition events. As a result, there is still a need to develop methods capable of monitoring ENM-cell interactions independent of surface modification. Addressing these concerns, here we show how scatter enhanced phase contrast (SEPC) microscopy can be extended to work as a generalized label-free approach for monitoring nanoparticle uptake and transport dynamics. To determine which materials can be studied using SEPC, we turn to Lorenz-Mie theory, which predicts that individual particles down to ∼35 nm can be observed. We confirm this experimentally, demonstrating that SEPC works for a variety of metal and metal oxides, including Au, Ag, TiO2, CeO2, Al2O3, and Fe2O3 nanoparticles. We then demonstrate that SEPC microscopy can be used in a quantitative, time-dependent fashion to discriminate between distinct modes of active cellular transport, including intracellular transport and membrane-assisted transport. Finally, we combine this technique with microcontact printing to normalize transport dynamics across multiple cells, allowing for a careful study of ensemble TiO2 nanoparticle uptake. This revealed three distinct regions of particle transport across the cell, indicating that membrane dynamics play an important role in regulating particle flow. By avoiding fluorescent labels, SEPC allows for a rational exploration of the surface properties of nanomaterials in their native state and their role in endocytosis and cellular transport.

A nano-carrier platform for the targeted delivery of nature-inspired antimicrobials using Engineered Water Nanostructures for food safety applications.

Despite the progress in the area of food safety, foodborne diseases still represent a massive challenge to the public health systems worldwide, mainly due to the substantial inefficiencies across the farm-to-fork continuum. Here, we report the development of a nano-carrier platform, for the targeted and precise delivery of antimicrobials for the inactivation of microorganisms on surfaces using Engineered Water Nanostructures (EWNS). An aqueous suspension of an active ingredient (AI) was used to synthesize iEWNS, with the 'i' denoting the AI used in their synthesis, using a combined electrospray and ionization process. The iEWNS possess unique, active-ingredient-dependent physicochemical properties: i) they are engineered to have a tunable size in the nanoscale; ii) they have excessive electric surface charge, and iii) they contain both the reactive oxygen species (ROS) formed due to the ionization of deionized (DI) water, and the AI used in their synthesis. Their charge can be used in combination with an electric field to target them onto a surface of interest. In this approach, a number of nature-inspired antimicrobials, such as H2O2, lysozyme, citric acid, and their combination, were used to synthesize a variety of iEWNS-based nano-sanitizers. It was demonstrated through foodborne-pathogen-inactivation experiments that due to the targeted and precise delivery, and synergistic effects of AI and ROS incorporated in the iEWNS structure, a pico- to nanogram-level dose of the AI delivered to the surface using this nano-carrier platform is capable of achieving 5-log reductions in minutes of exposure time. This aerosol-based, yet 'dry' intervention approach using iEWNS nano-carrier platform offers advantages over current 'wet' techniques that are prevalent commercially, which require grams of the AI to achieve similar inactivation, leading to increased chemical risks and chemical waste byproducts. Such a targeted nano-carrier approach has the potential to revolutionize the delivery of antimicrobials for sterilization in the food industry.

Dispersion preparation, characterization, and dosimetric analysis of cellulose nano-fibrils and nano-crystals: Implications for cellular toxicological studies.

The characterization of cellulose-based nanomaterial (CNM) suspensions in environmental and biological media is impaired because of their high carbon content and anisotropic shape, thus making it difficult to derive structure activity relationships (SAR) in toxicological studies. Here, a standardized method for the dispersion preparation and characterization of cellulose nanofibrils (CNF) and nanocrystals (CNC) in biological and environmental media was developed. Specifically, electron microscopy was utilized and allowed to specify optimum practices for efficiently suspending CNF and CNC in water and cell culture medium. Furthermore, a technique for measuring the in vitro particle kinetics of CNF and CNC suspended in cell culture medium utilizing fluorescently tagged materials was developed to assess the delivery rate of such CNM at the bottom of the well. Interestingly, CNF were shown to settle and create a loosely packed layer at the bottom of cell culture wells within a few hours. On the contrary, CNC settled gradually at a significantly slower rate, highlighting the discordance between administered and delivered mass dose. This work is both novel and urgent in the field of environmental health and safety as it introduces well-defined techniques for the dispersion and characterization of emerging, cellulose-based engineered nanomaterials. It also provides useful insights to the in vitro behavior of suspended anisotropic nanomaterials in general, which should enable dosimetry and comparison of toxicological data across laboratories as well as promote the safe and sustainable use of nanotechnology.

Development of reference metal and metal oxide engineered nanomaterials for nanotoxicology research using high throughput and precision flame spray synthesis approaches.

There is a growing need to develop and characterize reference metal and metal oxide engineered nanomaterials (ENMs) of high purity and tunable intrinsic properties suitable for nanotoxicology research. Here a high throughput (volume) and precision flame spray pyrolysis (FSP) approach coupled with state-of-the-art characterization techniques are utilized to generate such reference ENMs. The lab-based and industrially relevant FSP system, termed as Versatile Engineered Nanomaterials Generation System (VENGES), synthesizes the metals and metal oxides, at high throughput manner with controlled properties, such as primary particle size, aggregate diameter, shape, crystallinity, stoichiometry and surface chemistry. A nanopanel of nine reference ENMs (silica, silver, silver supported on silica, alumina, ceria and iron oxide) was synthesized and characterized using combined electron microscopy, advanced spectroscopic techniques and physical analyses (e.g., BET, XRD, TEM, pycnometry, XPS, ICP-MS and FTIR). ENMs show a high degree of chemical purity and stoichiometry, and low content of carbon residuals, and are sterile and free of bacteria and endotoxins. Further, their colloidal properties and their implication in in-vitro dosimetry have been also investigated in both environmental and test biological media. The suitability of reference ENMs and protocols developed in this study brings forth new arenas to generate reliable and reproducible toxicological data in an effort to reduce conflicting and contradicting inter-laboratory data on relative toxic effects of ENMs.

Reducing Intestinal Digestion and Absorption of Fat Using a Nature-Derived Biopolymer: Interference of Triglyceride Hydrolysis by Nanocellulose.

Engineered nanomaterials are increasingly added to foods to improve quality, safety, or nutrition. Here we report the ability of ingested nanocellulose (NC) materials to reduce digestion and absorption of ingested fat. In the small intestinal phase of an acellular simulated gastrointestinal tract, the hydrolysis of free fatty acids (FFA) from triglycerides (TG) in a high-fat food model was reduced by 48.4% when NC was added at 0.75% w/w to the food, as quantified by pH stat titration, and by 40.1% as assessed by fluorometric FFA assay. Furthermore, translocation of TG and FFA across an in vitro cellular model of the intestinal epithelium was significantly reduced by the presence of 0.75% w/w NC in the food (TG by 52% and FFA by 32%). Finally, in in vivo experiments, the postprandial rise in serum TG 1 h after gavage with the high fat food model was reduced by 36% when 1.0% w/w NC was administered with the food. Scanning electron microscopy and molecular dynamics studies suggest two primary mechanisms for this effect: (1) coalescence of fat droplets on fibrillar NC (CNF) fibers, resulting in a reduction of available surface area for lipase binding and (2) sequestration of bile salts, causing impaired interfacial displacement of proteins at the lipid droplet surface and impaired solubilization of lipid digestion products. Together these findings suggest a potential use for NC, as a food additive or supplement, to reduce absorption of ingested fat and thereby assist in weight loss and the management of obesity.

Nanoparticle Wettability Influences Nanoparticle-Phospholipid Interactions.

We explored the influence of nanoparticle (NP) surface charge and hydrophobicity on NP-biomolecule interactions by measuring the composition of adsorbed phospholipids on four NPs, namely, positively charged CeO2 and ZnO and negatively charged BaSO4 and silica-coated CeO2, after exposure to bronchoalveolar lavage fluid (BALf) obtained from rats, and to a mixture of neutral dipalmitoyl phosphatidylcholine (DPPC) and negatively charged dipalmitoyl phosphatidic acid (DPPA). The resulting NP-lipid interactions were examined by cryogenic transmission electron microscopy (cryo-TEM) and atomic force microscopy (AFM). Our data show that the amount of adsorbed lipids on NPs after incubation in BALf and the DPPC/DPPA mixture was higher in CeO2 than in the other NPs, qualitatively consistent with their relative hydrophobicity. The relative concentrations of specific adsorbed phospholipids on NP surfaces were different from their relative concentrations in the BALf. Sphingomyelin was not detected in the extracted lipids from the NPs despite its >20% concentration in the BALf. AFM showed that the more hydrophobic CeO2 NPs tended to be located inside lipid vesicles, whereas less hydrophobic BaSO4 NPs appeared to be outside. In addition, cryo-TEM analysis showed that CeO2 NPs were associated with the formation of multilamellar lipid bilayers, whereas BaSO4 NPs with unilamellar lipid bilayers. These data suggest that the NP surface hydrophobicity predominantly controls the amounts and types of lipids adsorbed, as well as the nature of their interaction with phospholipids.

Mussel-inspired 3D fiber scaffolds for heart-on-a-chip toxicity studies of engineered nanomaterials.

Due to the unique physicochemical properties exhibited by materials with nanoscale dimensions, there is currently a continuous increase in the number of engineered nanomaterials (ENMs) used in consumer goods. However, several reports associate ENM exposure to negative health outcomes such as cardiovascular diseases. Therefore, understanding the pathological consequences of ENM exposure represents an important challenge, requiring model systems that can provide mechanistic insights across different levels of ENM-based toxicity. To achieve this, we developed a mussel-inspired 3D microphysiological system (MPS) to measure cardiac contractility in the presence of ENMs. While multiple cardiac MPS have been reported as alternatives to in vivo testing, most systems only partially recapitulate the native extracellular matrix (ECM) structure. Here, we show how adhesive and aligned polydopamine (PDA)/polycaprolactone (PCL) nanofiber can be used to emulate the 3D native ECM environment of the myocardium. Such nanofiber scaffolds can support the formation of anisotropic and contractile muscular tissues. By integrating these fibers in a cardiac MPS, we assessed the effects of TiO2 and Ag nanoparticles on the contractile function of cardiac tissues. We found that these ENMs decrease the contractile function of cardiac tissues through structural damage to tissue architecture. Furthermore, the MPS with embedded sensors herein presents a way to non-invasively monitor the effects of ENM on cardiac tissue contractility at different time points. These results demonstrate the utility of our MPS as an analytical platform for understanding the functional impacts of ENMs while providing a biomimetic microenvironment to in vitro cardiac tissue samples. Graphical Abstract Heart-on-a-chip integrated with mussel-inspired fiber scaffolds for a high-throughput toxicological assessment of engineered nanomaterials.

Analysis of lipid adsorption on nanoparticles by nanoflow liquid chromatography-tandem mass spectrometry.

Nanoparticles (NPs) tend to adsorb matrix molecules like proteins and lipids incubated with biological fluids, forming a biological corona. While the formation and functions of protein corona have been studied extensively, little attention has been paid to lipid adsorption on NPs. However, lipids are also abundantly present in biological fluids and play important roles in processes like cell signaling and angiogenesis. Therefore, in this study, we established the analytical procedure for study of lipid adsorption on three different types of NPs in two matrices: human serum and heavy cream, using nanoflow liquid chromatography-mass spectrometry (nanoflowLC-MS). Serum was chosen to represent the common environment the NPs would be present once entering human body, and heavy cream was the representative food matrix NPs may be added to improve the color or taste. Steps of liquid-liquid extraction were established and optimized to achieve maximum recovery of the adsorbed, standard lipids from the NPs. Then, the LC-MS/MS method was developed to attain base-line separation of the standard lipids that represent the major lipid classes. At last, the lipid adsorption profiles of the three NPs were compared. We found that the lipid adsorption profile on the same type of NP was significantly different between the two matrices. The established method will help us investigate lipid adsorption on additional NPs and reveal how it could be affected by the physiochemical properties of NPs and the presence of proteins and other components in the biological matrix.

Assessing electronic cigarette emissions: linking physico-chemical properties to product brand, e-liquid flavoring additives, operational voltage and user puffing patterns.

Users of electronic cigarettes (e-cigs) are exposed to particles and other gaseous pollutants. However, major knowledge gaps on the physico-chemical properties of such exposures and contradictory data in published literature prohibit health risk assessment. Here, the effects of product brand, type, e-liquid flavoring additives, operational voltage, and user puffing patterns on emissions were systematically assessed using a recently developed, versatile, e-cig exposure generation platform and state-of-the-art analytical methods. Parameters of interest in this systematic evaluation included two brands (A and B), three flavors (tobacco, menthol, and fruit), three types of e-cigs (disposable, pre-filled, and refillable tanks), two puffing protocols (4 and 2 s/puff), and four operational voltages (2.2-5.7 V). Particles were generated at a high number concentration (106-107 particles/cm3). The particle size distribution was bi-modal (∼200 nm and 1 µm). Furthermore, organic species (humectants propylene glycol and glycerin, nicotine) that were present in e-liquid and trace metals (potassium and sodium) that were present on e-cig heating coil were also released into the emission. In addition, combustion-related byproducts, such as benzene and toluene, were also detected in the range of 100-38,000 ppbv/puff. Parametric analyzes performed in this study show the importance of e-cig brand, type, flavor additives, user puffing pattern (duration and frequency), and voltage on physico-chemical properties of emissions. This observed influence is indicative of the complexity associated with the toxicological screening of emissions from e-cigs and needs to be taken into consideration.

Effective delivery of sonication energy to fast settling and agglomerating nanomaterial suspensions for cellular studies: Implications for stability, particle kinetics, dosimetry and toxicity.

Typical in vitro assays used for high throughput toxicological screening and measuring nano-bio interactions are conducted by pipetting suspensions of engineered nanomaterials (ENMs) dispersed in nutrient-rich culture media directly onto cells. In order to achieve fairly monodisperse and stable suspensions of small agglomerates, ultrasonic energy is usually applied to break apart large agglomerates that can form upon suspension in liquid. Lack of standardized protocols and methods for delivering sonication energy can introduce variability in the ENM suspension properties (e.g. agglomerate size, polydispersity, suspension stability over time), and holds significant implications for in vitro dosimetry, toxicity, and other nano-bio interactions. Careful assessment of particle transformations during dispersion preparation and sonication is therefore critical for accurate interpretation of in vitro toxicity studies. In this short communication, the difficulties of preparing stable suspensions of rapidly settling ENMs are presented. Furthermore, methods to optimize the delivery of the critical sonication energy required to break large agglomerates and prepare stable, fairly monodispersed suspensions of fast settling ENMs are presented. A methodology for the efficient delivery of sonication energy in a discrete manner is presented and validated using various rapidly agglomerating and settling ENMs. The implications of continuous vs. discrete sonication on average hydrodynamic diameter, and polydispersity was also assessed for both fast and slow settling ENMs. For the rapidly agglomerating and settling ENMs (Ag15%/SiO2, Ag and CeO2), the proposed discrete sonication achieved a significant reduction in the agglomerate diameter and polydispersity. In contrast, the relatively slow agglomerating and settling Fe2O3 suspension did not exhibit statistically significant differences in average hydrodynamic diameter or polydispersity between the continuous and discrete sonication approaches. Our results highlight the importance of using the proposed material-specific discrete sonication method to effectively deliver the critical sonication energy necessary to reproducibly achieve stable and fairly monodispersed suspensions that are suitable for in vitro toxicity testing.

An integrated electrolysis - electrospray - ionization antimicrobial platform using Engineered Water Nanostructures (EWNS) for food safety applications.

Engineered water nanostructures (EWNS) synthesized utilizing electrospray and ionization of water, have been, recently, shown to be an effective, green, antimicrobial platform for surface and air disinfection, where reactive oxygen species (ROS), generated and encapsulated within the particles during synthesis, were found to be the main inactivation mechanism. Herein, the antimicrobial potency of the EWNS was further enhanced by integrating electrolysis, electrospray and ionization of de-ionized water in the EWNS synthesis process. Detailed physicochemical characterization of these enhanced EWNS (eEWNS) was performed using state-of-the-art analytical methods and has shown that, while both size and charge remain similar to the EWNS (mean diameter of 13 nm and charge of 13 electrons), they possess a three times higher ROS content. The increase of the ROS content as a result of the addition of the electrolysis step before electrospray and ionization led to an increased antimicrobial ability as verified by E. coli inactivation studies using stainless steel coupons. It was shown that a 45-minute exposure to eEWNS resulted in a 4-log reduction as opposed to a 1.9-log reduction when exposed to EWNS. In addition, the eEWNS were assessed for their potency to inactivate natural microbiota (total viable and yeast and mold counts), as well as, inoculated E.coli on the surface of fresh organic blackberries. The results showed a 97% (1.5-log) inactivation of the total viable count, a 99% (2-log) reduction in the yeast and mold count and a 2.5-log reduction of the inoculated E.coli after 45 minutes of exposure, without any visual changes to the fruit. This enhanced antimicrobial activity further underpins the EWNS platform as an effective, dry and chemical free approach suitable for a variety of food safety applications and could be ideal for delicate fresh produce that cannot withstand the classical, wet disinfection treatments.

Development of high throughput, high precision synthesis platforms and characterization methodologies for toxicological studies of nanocellulose.

Cellulose is one of the most abundant natural polymers, is readily available, biodegradable, and inexpensive. Recently, interest is growing around nanoscale cellulose due to the sustainability of these materials, the novel properties, and the overall low environmental impact. The rapid expansion of nanocellulose uses in various applications makes the study of the toxicological properties of these materials of great importance to public health regulators. However, most of the current toxicological studies are highly conflicting, inconclusive, and contradictory. The major reasons for these discrepancies are the lack of standardized methods to produce industry-relevant reference nanocellulose and relevant characterization that will expand beyond the traditional cellulose characterization for applications. In order to address these issues, industry-relevant synthesis platforms were developed to produce nanocellulose of controlled properties that can be used as reference materials in toxicological studies. Herein, two types of nanocellulose were synthesized, cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) using the friction grinding platform and an acid hydrolysis approach respectively. The nanocellulose structures were characterized extensively regarding their physicochemical properties, including testing for endotoxins and bacteria contamination.

Potential impact of inorganic nanoparticles on macronutrient digestion: titanium dioxide nanoparticles slightly reduce lipid digestion under simulated gastrointestinal conditions.

Titanium dioxide (TiO2) particles are used in some food products to alter their optical properties, such as whiteness or brightness. These additives typically contain a population of TiO2 nanoparticles (d < 100 nm), which has led to concern about their potential toxicity. The objective of this study was to examine the impact of TiO2 particles on the gastrointestinal fate of oil-in-water emulsions using a simulated gastrointestinal tract (GIT) that includes mouth, stomach, and small intestine phases. Theoretical predictions suggested that TiO2 nanoparticles might inhibit lipid digestion through two physicochemical mechanisms: (i) a fraction of the lipase adsorbs to TiO2 particle surfaces, thereby reducing the amount available to hydrolyze lipid droplets; (ii) some TiO2 particles adsorb to the surfaces of lipid droplets, thereby reducing the lipid surface area exposed to lipase. The importance of these mechanisms was tested by passing protein-coated lipid droplets (2%, w/w) through the simulated GIT in the absence and presence of TiO2 (0.5%, w/w) nanoparticles (18 nm) and fine particles (167 nm). Changes in particle characteristics (size, organization, and charge) and lipid digestion were then measured. Both TiO2 nanoparticles and fine particles had little impact on the aggregation state and charge of the lipid droplets in the different GIT regions, as well as on the rate and extent of lipid digestion. This suggests that the theoretically predicted impact of particle size on lipid digestion was not seen in practice.

Protein corona: implications for nanoparticle interactions with pulmonary cells.

BACKGROUND: We previously showed that cerium oxide (CeO2), barium sulfate (BaSO4) and zinc oxide (ZnO) nanoparticles (NPs) exhibited different lung toxicity and pulmonary clearance in rats. We hypothesize that these NPs acquire coronas with different protein compositions that may influence their clearance from the lungs. METHODS: CeO2, silica-coated CeO2, BaSO4, and ZnO NPs were incubated in rat lung lining fluid in vitro. Then, gel electrophoresis followed by quantitative mass spectrometry was used to characterize the adsorbed proteins stripped from these NPs. We also measured uptake of instilled NPs by alveolar macrophages (AMs) in rat lungs using electron microscopy. Finally, we tested whether coating of gold NPs with albumin would alter their lung clearance in rats. RESULTS: We found that the amounts of nine proteins in the coronas formed on the four NPs varied significantly. The amounts of albumin, transferrin and α-1 antitrypsin were greater in the coronas of BaSO4 and ZnO than that of the two CeO2 NPs. The uptake of BaSO4 in AMs was less than CeO2 and silica-coated CeO2 NPs. No identifiable ZnO NPs were observed in AMs. Gold NPs coated with albumin or citrate instilled into the lungs of rats acquired the similar protein coronas and were cleared from the lungs to the same extent. CONCLUSIONS: We show that different NPs variably adsorb proteins from the lung lining fluid. The amount of albumin in the NP corona varies as does NP uptake by AMs. However, albumin coating does not affect the translocation of gold NPs across the air-blood barrier. A more extensive database of corona composition of a diverse NP library will develop a platform to help predict the effects and biokinetics of inhaled NPs.