Sijie Lin | University of California, Los Angeles (original) (raw)

Papers by Sijie Lin

ACS Nano, 2015

Engineered carbonaceous nanomaterials (ECNs), including single-wall carbon nanotubes (SWCNTs), mu... more Engineered carbonaceous nanomaterials (ECNs), including single-wall carbon nanotubes (SWCNTs), multiwall carbon nanotubes (MWCNTs), graphene, and graphene oxide (GO), are potentially hazardous to the lung. With incremental experience in the use of predictive toxicological approaches, seeking to relate ECN physicochemical properties to adverse outcome pathways (AOPs), it is logical to explore the existence of a common AOP that allows comparative analysis of broad ECN categories. We established an ECN library comprising three different types of SWCNTs, graphene, and graphene oxide (two sizes) for comparative analysis according to a cellbased AOP that also plays a role in the pathogenesis of pulmonary fibrosis. SWCNTs synthesized by Hipco, arc discharge and CoÀMo catalyst (CoMoCAT) methods were obtained in their as-prepared (AP) state, following which they were further purified (PD) or coated with Pluronic F108 (PF108) or bovine serum albumin (BSA) to improve dispersal and colloidal stability. GO was prepared as two sizes, GO-small (S) and GO-large (L), while the graphene samples were coated with BSA and PF108 to enable dispersion in aqueous solution. In vitro screening showed that AP-and PD-SWCNTs, irrespective of the method of synthesis, as well as graphene (BSA) and GO (S and L) could trigger interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) production in myeloid (THP-1) and epithelial (BEAS-2B) cell lines, respectively. Oropharyngeal aspiration in mice confirmed that AP-Hipco tubes, graphene (BSA-dispersed), GO-S and GO-L could induce IL-1β and TGF-β1 production in the lung in parallel with lung fibrosis. Notably, GO-L was the most pro-fibrogenic material based on rapid kinetics of pulmonary injury. In contrast, PF108-dispersed SWCNTs and -graphene failed to exert fibrogenic effects. Collectively, these data indicate that the dispersal state and surface reactivity of ECNs play key roles in triggering a pro-fibrogenic AOP, which could prove helpful for hazard ranking and a proposed tiered testing approach for large ECN categories.

The rapid accumulation of disposed plastics in the environment, especially in the Pacific Ocean, ... more The rapid accumulation of disposed plastics in the environment, especially in the Pacific Ocean, has become a global concern in recent years. Photo, chemical and physical degradations constantly fragment these plastics into a wide array of macroscopic to microscopic particles. As a result, marine organisms such as algae may be exposed to plastic particles through ingestion, adsorption and other forms

The exposure of living systems to nanoparticles is inevitable due to a dramatic increase in their... more The exposure of living systems to nanoparticles is inevitable due to a dramatic increase in their release into the environment, the most likely pathways being through inhalation, ingestion and skin uptake. The extremely small size of the nanoparticles may facilitate their tissue and cellular uptake by plants and animals, resulting in either positive (drug delivery, antioxidation) or negative (toxicity, cellular dysfunction) effects. Here we report the effects of quantum dots uptake by algae, the single-celled plant species and major food sources for aquatic organisms. In our studies, the presence of quantum dots in algal cells was detected using fluorescence microscopy and electron microscopy. Using spectrophotometry we found a supralinear increase of the uptake with the concentration of quantum dots, with a saturation of the uptake occurring beyond a concentration of 15 mg/mL. Using a bicarbonate indicator we further evaluated the effects of quantum dots uptake on algal photosynthe...

The physical adsorption of nanosized plastic beads onto a model cellulose film and two living alg... more The physical adsorption of nanosized plastic beads onto a model cellulose film and two living algal species, Chlorella and Scenedesmus, has been studied. This adsorption has been found to ubiquitously favor positively charged over negatively charged plastic beads due to the electrostatic attraction between the beads and the cellulose constituent of the model and living systems. Such a charge preference is especially pronounced for Chlorella and Scenedesmus, whose binding with the plastic beads also depended upon algal morphology and motility, as characterized by the Freundlich coefficients. Using a CO 2 depletion assay, we show that the adsorption of plastic beads hindered algal photosynthesis, possibly through the physical blockage of light and air flow by the nanoparticles. Our ROS assay further indicated that plastic adsorption promoted algal ROS production. Such algal responses to plastic exposure may have implications on the sustainability of the aquatic food chain.

We have previously demonstrated that there is a relationship between the aspect ratio (AR) of CeO... more We have previously demonstrated that there is a relationship between the aspect ratio (AR) of CeO 2 nanoparticles and in vitro hazard potential. CeO 2 nanorods with AR g 22 induced lysosomal damage and progressive effects on IL-1β production and cytotoxicity in the human myeloid cell line, THP-1. In order to determine whether this toxicological paradigm for long aspect ratio (LAR) CeO 2 is also relevant in vivo, we performed comparative studies in the mouse lung and gastrointestinal tract (GIT) of zebrafish larvae.

ABSTRACT Nanotechnology is growing rapidly and increasing number of consumer goods contains engin... more ABSTRACT Nanotechnology is growing rapidly and increasing number of consumer goods contains engineered nanoparticles (ENPs). Various new products with nanoparticles are being introduced and new applications of nanotechnology are being explored. The use of nanotechnology in food and agriculture sector is also growing rapidly. Major food companies are exploring the use of nanotechnology to develop advanced food packaging and smart' food products. Similarly, farm applications of nanotechnology are being explored by agriculture related industry to improve the precision of farming operations. With these rapid developments, release of ENPs into the environment and contamination of irrigation waters may be inevitable. While consumer products containing ENPs are increasing, very few reports exist to assess the impact of ENPs on ecological systems including plants, wild life, and humans. In preliminary experiments, we observed that pepper and rice seeds absorbed fullerenes (C70 nanocarbon particles) through the seed coat during imbibition and as the seedlings grew fullerenes moved through the vascular system. In rice, fullerenes delayed flowering, reduced seed setting and were transmitted to the next generation plants. We also observed that the roots could take up fullerenes in irrigation water. As water evaporated through the stomata, fullerenes accumulated at the stomatal opening, which could influence gas movement through the stomata and eventually affect metabolic processes and the productivity. Our work also showed that quantum dots at high concentrations reduced the photosynthetic ability of algae. Possible implication of nanoparticles on agro ecosystems will be discussed.

The zebrafi sh is emerging as a model organism for the safety assessment and hazard ranking of en... more The zebrafi sh is emerging as a model organism for the safety assessment and hazard ranking of engineered nanomaterials. In this Communication, the implementation of a roboticized high-throughput screening (HTS) platform with automated image analysis is demonstrated to assess the impact of dissolvable oxide nanoparticles on embryo hatching. It is further demonstrated that this hatching interference is mechanistically linked to an effect on the metalloprotease, ZHE 1, which is responsible for degradation of the chorionic membrane. The data indicate that 4 of 24 metal oxide nanoparticles (CuO, ZnO, Cr 2 O 3 , and NiO) could interfere with embryo hatching by a chelator-sensitive mechanism that involves ligation of critical histidines in the ZHE1 center by the shed metal ions. A recombinant ZHE1 enzymatic assay is established to demonstrate that the dialysates from the same materials responsible for hatching interference also inhibit ZHE1 activity in a dose-dependent fashion. A peptide-based BLAST search identifi es several additional aquatic species that express enzymes with homologous histidine-based catalytic centers, suggesting that the ZHE1 mechanistic paradigm could be used to predict the toxicity of a large number of oxide nanoparticles that pose a hazard to aquatic species.

To uncover the size influence of TiO(2) nanoparticles on their potential toxicity, the cytotoxici... more To uncover the size influence of TiO(2) nanoparticles on their potential toxicity, the cytotoxicity of different-sized TiO(2) nanoparticles with and without photoactivation was tested. It was demonstrated that without photoactivation, TiO(2) nanoparticles were inert up to 100 μg/ml. On the contrary, with photoactivation, the toxicity of TiO(2) nanoparticles significantly increased, which correlated well with the specific surface area of the particles. Our results also suggest that the generation of hydroxyl radicals and reactive oxygen species (ROS)-mediated damage to the surface-adsorbed biomolecules could be the two major reasons for the cytotoxicity of TiO(2) nanoparticles after photoactivation. Higher ROS generation from smaller particles was detected under both biotic and abiotic conditions. Smaller particles could adsorb more proteins, which was confirmed by thermogravimetric analysis. To further investigate the influence of the generation of hydroxyl radicals and adsorption of protein, poly (ethylene-alt-maleic anhydride) (PEMA) and chitosan were used to coat TiO(2) nanoparticles. The results confirmed that surface coating of TiO(2) nanoparticles could reduce such toxicity after photoactivation, by hindering adsorption of biomolecules and generation of hydroxyl radical (·OH) during photoactivation.

A phenotype recognition model was developed for high throughput screening (HTS) of engineered Nan... more A phenotype recognition model was developed for high throughput screening (HTS) of engineered Nano-Materials (eNMs) toxicity using zebrafish embryo developmental response classified, from automatically captured images and without manual manipulation of zebrafish positioning, by three basic phenotypes (i.e., hatched, unhatched, and dead). The recognition model was built with a set of vectorial descriptors providing image color and texture information. The best performing model was attained with three image descriptors (color histogram, representative color, and color layout) identified as most suitable from an initial pool of six descriptors. This model had an average recognition accuracy of 97.4060.95% in a 10-fold cross-validation and 93.75% in a stress test of low quality zebrafish images. The present work has shown that a phenotyping model can be developed with accurate recognition ability suitable for zebrafish-based HTS assays. Although the present methodology was successfully demonstrated for only three basic zebrafish embryonic phenotypes, it can be readily adapted to incorporate more subtle phenotypes.

Small (Weinheim an der Bergstrasse, Germany), Jan 29, 2014

Since more than 30% of consumer products that include engineered nanomaterials contain nano-Ag, t... more Since more than 30% of consumer products that include engineered nanomaterials contain nano-Ag, the safety of this material is of considerable public concern. In this study, Ag nanoparticles (NPs) are used to demonstrate that 20 nm polyvinylpyrrolidone (PVP or P) and citrate (C)-coated Ag NPs induce more cellular toxicity and oxidative stress than larger (110 nm) particles due to a higher rate of dissolution and Ag bioavailability. Moreover, there is also a higher propensity for citrate 20 nm (C20) nanoparticles to generate acute neutrophilic inflammation in the lung and to produce chemokines compared to C110. P110 has less cytotoxic effects than C110, likely due to the ability of PVP to complex released Ag(+) . In contrast to the more intense acute pulmonary effects of C20, C110 induces mild pulmonary fibrosis at day 21, likely as a result of slow but persistent Ag(+) release leading to a sub-chronic injury response. Interestingly, the released metallic Ag is incorporated into the ...

Physical Chemistry Chemical Physics, 2010

We describe herein an adsorption-induced energy transfer between phenanthrene, a major environmen... more We describe herein an adsorption-induced energy transfer between phenanthrene, a major environmental pollutant, and a fluorescently labeled dendrimer acting as a host molecule. We find experimentally that such energy transfer is the most efficient at a solvent pH of 8 and for a phenanthrene ...

2010 3rd International Nanoelectronics Conference (INEC), 2010

We report on the binding of nanoplastics onto a thin film of cellulose - the primary structural c... more We report on the binding of nanoplastics onto a thin film of cellulose - the primary structural component of the cell-wall of green plants, many forms of algae and the oomycetes. The binding capacities of neutral and negatively charged nanoplastics were compared. Data from a fluorescence microplate reader showed that the adsorption of the neutral nanoplastic beads to be stronger

ACS nano, Jan 27, 2015

Although copper-containing nanoparticles are used in commercial products such as fungicides and b... more Although copper-containing nanoparticles are used in commercial products such as fungicides and bactericides, we presently do not understand the environmental impact on other organisms that may be inadvertently exposed. In this study, we used the zebrafish embryo as a screening tool to study the potential impact of two nano Cu-based materials, CuPRO and Kocide, in comparison to nano-sized and micron-sized Cu and CuO particles in their pristine form (0 - 10 ppm) as well as following their transformation in an experimental wastewater treatment system. This was accomplished by construction of a modeled domestic septic tank system from which effluents could be retrieved at different stages following particle introduction (10 ppm). The Cu speciation in the effluent was identified as non-dissolvable inorganic Cu(H2PO2)2 and non-diffusible organic Cu by X-ray diffraction, inductively coupled plasma mass spectrometry (ICP-MS), diffusive gradients in thin-films (DGT), and Visual MINTEQ softw...

The Journal of Physical Chemistry C, 2010

The physical adsorption of nanosized plastic beads onto a model cellulose film and two living alg... more The physical adsorption of nanosized plastic beads onto a model cellulose film and two living algal species, Chlorella and Scenedesmus, has been studied. This adsorption has been found to ubiquitously favor positively charged over negatively charged plastic beads due to the electrostatic attraction between the beads and the cellulose constituent of the model and living systems. Such a charge preference is especially pronounced for Chlorella and Scenedesmus, whose binding with the plastic beads also depended upon algal morphology and motility, as characterized by the Freundlich coefficients. Using a CO 2 depletion assay, we show that the adsorption of plastic beads hindered algal photosynthesis, possibly through the physical blockage of light and air flow by the nanoparticles. Our ROS assay further indicated that plastic adsorption promoted algal ROS production. Such algal responses to plastic exposure may have implications on the sustainability of the aquatic food chain.

The Journal of Physical Chemistry C, 2009

We report on the adsorption of CdSe/ZnS quantum dots and its effects on algal photosynthesis. A l... more We report on the adsorption of CdSe/ZnS quantum dots and its effects on algal photosynthesis. A logarithmic trend was established for the adsorption process using UV-vis spectrophotometry, with Freundlich constants determined as k ) 0.588 ppm 1-n and n ) 0.629. Both our CO 2 depletion and O 2 production assays showed a significantly inhibited photosynthetic activity of the algae exposed to the quantum dots, suggesting the potential impact of nanoparticle adsorption on the photochemistry of plant species.

ACS Nano, 2015

Engineered carbonaceous nanomaterials (ECNs), including single-wall carbon nanotubes (SWCNTs), mu... more Engineered carbonaceous nanomaterials (ECNs), including single-wall carbon nanotubes (SWCNTs), multiwall carbon nanotubes (MWCNTs), graphene, and graphene oxide (GO), are potentially hazardous to the lung. With incremental experience in the use of predictive toxicological approaches, seeking to relate ECN physicochemical properties to adverse outcome pathways (AOPs), it is logical to explore the existence of a common AOP that allows comparative analysis of broad ECN categories. We established an ECN library comprising three different types of SWCNTs, graphene, and graphene oxide (two sizes) for comparative analysis according to a cellbased AOP that also plays a role in the pathogenesis of pulmonary fibrosis. SWCNTs synthesized by Hipco, arc discharge and CoÀMo catalyst (CoMoCAT) methods were obtained in their as-prepared (AP) state, following which they were further purified (PD) or coated with Pluronic F108 (PF108) or bovine serum albumin (BSA) to improve dispersal and colloidal stability. GO was prepared as two sizes, GO-small (S) and GO-large (L), while the graphene samples were coated with BSA and PF108 to enable dispersion in aqueous solution. In vitro screening showed that AP-and PD-SWCNTs, irrespective of the method of synthesis, as well as graphene (BSA) and GO (S and L) could trigger interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) production in myeloid (THP-1) and epithelial (BEAS-2B) cell lines, respectively. Oropharyngeal aspiration in mice confirmed that AP-Hipco tubes, graphene (BSA-dispersed), GO-S and GO-L could induce IL-1β and TGF-β1 production in the lung in parallel with lung fibrosis. Notably, GO-L was the most pro-fibrogenic material based on rapid kinetics of pulmonary injury. In contrast, PF108-dispersed SWCNTs and -graphene failed to exert fibrogenic effects. Collectively, these data indicate that the dispersal state and surface reactivity of ECNs play key roles in triggering a pro-fibrogenic AOP, which could prove helpful for hazard ranking and a proposed tiered testing approach for large ECN categories.

The rapid accumulation of disposed plastics in the environment, especially in the Pacific Ocean, ... more The rapid accumulation of disposed plastics in the environment, especially in the Pacific Ocean, has become a global concern in recent years. Photo, chemical and physical degradations constantly fragment these plastics into a wide array of macroscopic to microscopic particles. As a result, marine organisms such as algae may be exposed to plastic particles through ingestion, adsorption and other forms

The exposure of living systems to nanoparticles is inevitable due to a dramatic increase in their... more The exposure of living systems to nanoparticles is inevitable due to a dramatic increase in their release into the environment, the most likely pathways being through inhalation, ingestion and skin uptake. The extremely small size of the nanoparticles may facilitate their tissue and cellular uptake by plants and animals, resulting in either positive (drug delivery, antioxidation) or negative (toxicity, cellular dysfunction) effects. Here we report the effects of quantum dots uptake by algae, the single-celled plant species and major food sources for aquatic organisms. In our studies, the presence of quantum dots in algal cells was detected using fluorescence microscopy and electron microscopy. Using spectrophotometry we found a supralinear increase of the uptake with the concentration of quantum dots, with a saturation of the uptake occurring beyond a concentration of 15 mg/mL. Using a bicarbonate indicator we further evaluated the effects of quantum dots uptake on algal photosynthe...

The physical adsorption of nanosized plastic beads onto a model cellulose film and two living alg... more The physical adsorption of nanosized plastic beads onto a model cellulose film and two living algal species, Chlorella and Scenedesmus, has been studied. This adsorption has been found to ubiquitously favor positively charged over negatively charged plastic beads due to the electrostatic attraction between the beads and the cellulose constituent of the model and living systems. Such a charge preference is especially pronounced for Chlorella and Scenedesmus, whose binding with the plastic beads also depended upon algal morphology and motility, as characterized by the Freundlich coefficients. Using a CO 2 depletion assay, we show that the adsorption of plastic beads hindered algal photosynthesis, possibly through the physical blockage of light and air flow by the nanoparticles. Our ROS assay further indicated that plastic adsorption promoted algal ROS production. Such algal responses to plastic exposure may have implications on the sustainability of the aquatic food chain.

We have previously demonstrated that there is a relationship between the aspect ratio (AR) of CeO... more We have previously demonstrated that there is a relationship between the aspect ratio (AR) of CeO 2 nanoparticles and in vitro hazard potential. CeO 2 nanorods with AR g 22 induced lysosomal damage and progressive effects on IL-1β production and cytotoxicity in the human myeloid cell line, THP-1. In order to determine whether this toxicological paradigm for long aspect ratio (LAR) CeO 2 is also relevant in vivo, we performed comparative studies in the mouse lung and gastrointestinal tract (GIT) of zebrafish larvae.

ABSTRACT Nanotechnology is growing rapidly and increasing number of consumer goods contains engin... more ABSTRACT Nanotechnology is growing rapidly and increasing number of consumer goods contains engineered nanoparticles (ENPs). Various new products with nanoparticles are being introduced and new applications of nanotechnology are being explored. The use of nanotechnology in food and agriculture sector is also growing rapidly. Major food companies are exploring the use of nanotechnology to develop advanced food packaging and smart' food products. Similarly, farm applications of nanotechnology are being explored by agriculture related industry to improve the precision of farming operations. With these rapid developments, release of ENPs into the environment and contamination of irrigation waters may be inevitable. While consumer products containing ENPs are increasing, very few reports exist to assess the impact of ENPs on ecological systems including plants, wild life, and humans. In preliminary experiments, we observed that pepper and rice seeds absorbed fullerenes (C70 nanocarbon particles) through the seed coat during imbibition and as the seedlings grew fullerenes moved through the vascular system. In rice, fullerenes delayed flowering, reduced seed setting and were transmitted to the next generation plants. We also observed that the roots could take up fullerenes in irrigation water. As water evaporated through the stomata, fullerenes accumulated at the stomatal opening, which could influence gas movement through the stomata and eventually affect metabolic processes and the productivity. Our work also showed that quantum dots at high concentrations reduced the photosynthetic ability of algae. Possible implication of nanoparticles on agro ecosystems will be discussed.

The zebrafi sh is emerging as a model organism for the safety assessment and hazard ranking of en... more The zebrafi sh is emerging as a model organism for the safety assessment and hazard ranking of engineered nanomaterials. In this Communication, the implementation of a roboticized high-throughput screening (HTS) platform with automated image analysis is demonstrated to assess the impact of dissolvable oxide nanoparticles on embryo hatching. It is further demonstrated that this hatching interference is mechanistically linked to an effect on the metalloprotease, ZHE 1, which is responsible for degradation of the chorionic membrane. The data indicate that 4 of 24 metal oxide nanoparticles (CuO, ZnO, Cr 2 O 3 , and NiO) could interfere with embryo hatching by a chelator-sensitive mechanism that involves ligation of critical histidines in the ZHE1 center by the shed metal ions. A recombinant ZHE1 enzymatic assay is established to demonstrate that the dialysates from the same materials responsible for hatching interference also inhibit ZHE1 activity in a dose-dependent fashion. A peptide-based BLAST search identifi es several additional aquatic species that express enzymes with homologous histidine-based catalytic centers, suggesting that the ZHE1 mechanistic paradigm could be used to predict the toxicity of a large number of oxide nanoparticles that pose a hazard to aquatic species.

To uncover the size influence of TiO(2) nanoparticles on their potential toxicity, the cytotoxici... more To uncover the size influence of TiO(2) nanoparticles on their potential toxicity, the cytotoxicity of different-sized TiO(2) nanoparticles with and without photoactivation was tested. It was demonstrated that without photoactivation, TiO(2) nanoparticles were inert up to 100 μg/ml. On the contrary, with photoactivation, the toxicity of TiO(2) nanoparticles significantly increased, which correlated well with the specific surface area of the particles. Our results also suggest that the generation of hydroxyl radicals and reactive oxygen species (ROS)-mediated damage to the surface-adsorbed biomolecules could be the two major reasons for the cytotoxicity of TiO(2) nanoparticles after photoactivation. Higher ROS generation from smaller particles was detected under both biotic and abiotic conditions. Smaller particles could adsorb more proteins, which was confirmed by thermogravimetric analysis. To further investigate the influence of the generation of hydroxyl radicals and adsorption of protein, poly (ethylene-alt-maleic anhydride) (PEMA) and chitosan were used to coat TiO(2) nanoparticles. The results confirmed that surface coating of TiO(2) nanoparticles could reduce such toxicity after photoactivation, by hindering adsorption of biomolecules and generation of hydroxyl radical (·OH) during photoactivation.

A phenotype recognition model was developed for high throughput screening (HTS) of engineered Nan... more A phenotype recognition model was developed for high throughput screening (HTS) of engineered Nano-Materials (eNMs) toxicity using zebrafish embryo developmental response classified, from automatically captured images and without manual manipulation of zebrafish positioning, by three basic phenotypes (i.e., hatched, unhatched, and dead). The recognition model was built with a set of vectorial descriptors providing image color and texture information. The best performing model was attained with three image descriptors (color histogram, representative color, and color layout) identified as most suitable from an initial pool of six descriptors. This model had an average recognition accuracy of 97.4060.95% in a 10-fold cross-validation and 93.75% in a stress test of low quality zebrafish images. The present work has shown that a phenotyping model can be developed with accurate recognition ability suitable for zebrafish-based HTS assays. Although the present methodology was successfully demonstrated for only three basic zebrafish embryonic phenotypes, it can be readily adapted to incorporate more subtle phenotypes.

Small (Weinheim an der Bergstrasse, Germany), Jan 29, 2014

Since more than 30% of consumer products that include engineered nanomaterials contain nano-Ag, t... more Since more than 30% of consumer products that include engineered nanomaterials contain nano-Ag, the safety of this material is of considerable public concern. In this study, Ag nanoparticles (NPs) are used to demonstrate that 20 nm polyvinylpyrrolidone (PVP or P) and citrate (C)-coated Ag NPs induce more cellular toxicity and oxidative stress than larger (110 nm) particles due to a higher rate of dissolution and Ag bioavailability. Moreover, there is also a higher propensity for citrate 20 nm (C20) nanoparticles to generate acute neutrophilic inflammation in the lung and to produce chemokines compared to C110. P110 has less cytotoxic effects than C110, likely due to the ability of PVP to complex released Ag(+) . In contrast to the more intense acute pulmonary effects of C20, C110 induces mild pulmonary fibrosis at day 21, likely as a result of slow but persistent Ag(+) release leading to a sub-chronic injury response. Interestingly, the released metallic Ag is incorporated into the ...

Physical Chemistry Chemical Physics, 2010

We describe herein an adsorption-induced energy transfer between phenanthrene, a major environmen... more We describe herein an adsorption-induced energy transfer between phenanthrene, a major environmental pollutant, and a fluorescently labeled dendrimer acting as a host molecule. We find experimentally that such energy transfer is the most efficient at a solvent pH of 8 and for a phenanthrene ...

2010 3rd International Nanoelectronics Conference (INEC), 2010

We report on the binding of nanoplastics onto a thin film of cellulose - the primary structural c... more We report on the binding of nanoplastics onto a thin film of cellulose - the primary structural component of the cell-wall of green plants, many forms of algae and the oomycetes. The binding capacities of neutral and negatively charged nanoplastics were compared. Data from a fluorescence microplate reader showed that the adsorption of the neutral nanoplastic beads to be stronger

ACS nano, Jan 27, 2015

Although copper-containing nanoparticles are used in commercial products such as fungicides and b... more Although copper-containing nanoparticles are used in commercial products such as fungicides and bactericides, we presently do not understand the environmental impact on other organisms that may be inadvertently exposed. In this study, we used the zebrafish embryo as a screening tool to study the potential impact of two nano Cu-based materials, CuPRO and Kocide, in comparison to nano-sized and micron-sized Cu and CuO particles in their pristine form (0 - 10 ppm) as well as following their transformation in an experimental wastewater treatment system. This was accomplished by construction of a modeled domestic septic tank system from which effluents could be retrieved at different stages following particle introduction (10 ppm). The Cu speciation in the effluent was identified as non-dissolvable inorganic Cu(H2PO2)2 and non-diffusible organic Cu by X-ray diffraction, inductively coupled plasma mass spectrometry (ICP-MS), diffusive gradients in thin-films (DGT), and Visual MINTEQ softw...

The Journal of Physical Chemistry C, 2010

The physical adsorption of nanosized plastic beads onto a model cellulose film and two living alg... more The physical adsorption of nanosized plastic beads onto a model cellulose film and two living algal species, Chlorella and Scenedesmus, has been studied. This adsorption has been found to ubiquitously favor positively charged over negatively charged plastic beads due to the electrostatic attraction between the beads and the cellulose constituent of the model and living systems. Such a charge preference is especially pronounced for Chlorella and Scenedesmus, whose binding with the plastic beads also depended upon algal morphology and motility, as characterized by the Freundlich coefficients. Using a CO 2 depletion assay, we show that the adsorption of plastic beads hindered algal photosynthesis, possibly through the physical blockage of light and air flow by the nanoparticles. Our ROS assay further indicated that plastic adsorption promoted algal ROS production. Such algal responses to plastic exposure may have implications on the sustainability of the aquatic food chain.

The Journal of Physical Chemistry C, 2009

We report on the adsorption of CdSe/ZnS quantum dots and its effects on algal photosynthesis. A l... more We report on the adsorption of CdSe/ZnS quantum dots and its effects on algal photosynthesis. A logarithmic trend was established for the adsorption process using UV-vis spectrophotometry, with Freundlich constants determined as k ) 0.588 ppm 1-n and n ) 0.629. Both our CO 2 depletion and O 2 production assays showed a significantly inhibited photosynthetic activity of the algae exposed to the quantum dots, suggesting the potential impact of nanoparticle adsorption on the photochemistry of plant species.