Yon Ju-Nam

Manufactured nanoparticles: An overview of their chemistry, interactions and potential environmental implications

The industrial scale production and wide variety of applications of manufactured nanoparticles (NPs) and their possible release in considerable amounts into the natural aquatic environment have produced an increasing concern among the nanotechnology and environmental science community. In order to address this issue, it is important to understand NP chemistry, preparation, reactivity and possible mechanisms involved in their interaction with the naturally occurring aquatic components, particularly natural colloids and NPs present in the aquatic systems. In this review, an overview of the chemistry of both manufactured and natural aquatic NPs is outlined. This review discusses the physico-chemical aspects of both type of NPs as an essential point to assess possible routes involved in manufactured NP fate in the natural aquatic environment and their toxicity. Key advances related to the characterisation of the manufactured NPs and natural colloids.

Interspecies comparisons on the uptake and toxicity of silver and cerium dioxide nanoparticles

An increasing number and quantity of manufactured nanoparticles are entering the environment as the diversity of their applications increases, and this will lead to the exposure of both humans and wildlife. However, little is known regarding their potential health effects. We compared the potential biological effects of silver (Ag; nominally 35 and 600-1,600 nm) and cerium dioxide (CeO(2;) nominally <25 nm and 1-5 µm) particles in a range of cell (human hepatocyte and intestinal and fish hepatocyte) and animal (Daphnia magna, Cyprinus carpio) models to assess possible commonalities in toxicity across taxa. A variety of analytical techniques were employed to characterize the particles and investigate their biological uptake. Silver particles were more toxic than CeO(2) in all test systems, and an equivalent mass dose of Ag nanoparticles was more toxic than larger micro-sized material. Cellular uptake of all materials tested was shown in C3A hepatocytes and Caco-2 intestinal cells, and for Ag, into the intestine, liver, gallbladder, and gills of carp exposed via the water. The commonalities in toxicity of these particle types across diverse biological systems suggest that cross-species extrapolations may be possible for metal nanoparticle test development in the future. Our findings also suggest transport of particles through the gastrointestinal barrier, which is likely to be an important uptake route when assessing particle risk.

Characterization of cerium oxide nanoparticles—Part 1: Size measurements

The present study gives an overview of some of the major aspects for consideration in the characterization of nanomaterials (NMs). Part 1 focuses on the measurement of particle size and size-related parameters using several analytical techniques such as transmission electron microscopy, atomic force microscopy, dynamic light scattering, X-ray diffraction, and Brunauer, Emmett, and Teller surface area measurements as applied to commercially available cerium oxide nanoparticles (NPs) and microparticles (MPs). Part 2 (see companion paper) considers nonsize-related characterization and analysis. The results are discussed in relation to the nature of the sample and preparation, and the analytical principles, limitations, and advantages of each technique. Accurate information on the particle size of the different fractions of a sample can be obtained by using a combination of different types of microscopy, spectroscopy, separation, and other techniques; this should inform ecotoxicological and environmental studies. The good agreement between the measured primary particle size of the NPs (~15 nm) by atomic force microscopy, transmission electron microscopy, X-ray diffraction, and Brunauer, Emmett, and Teller suggests that the primary particles are formed of semispherical single crystals. For MPs, all measurements agree that they are large particles in the range above the NPs (100 nm), with some difference between the measured sizes, possibly as a result of polydispersity effects. Additionally, our findings suggest that atomic force microscopy and transmission electron microscopy prepared by centrifugation methods provide consistent data at low concentrations when dynamic light scattering fails.

Formation of α-Dicarbonyl Compounds in Beer during Storage of Pilsner

With the aim of determining the formation of alpha-dicarbonyl intermediates during beer aging on the shelf, alpha-dicarbonyls were identified and quantified after derivatization with 1,2-diaminobenze to generate quinoxalines. The sensory effects of alpha-dicarbonyls were evaluated by the quantification of key Strecker aldehydes and by GC-olfactometry (GCO)analysis of beer headspace using solid phase microextraction. Four alpha-dicarbonyls, reported here for the first time, were detected in fresh and aged beers, three were derived from the 2,3-enolization pathway of mono- and disaccharides, and the fourth was derived from the epimerization of 3-deoxy-2-hexosulose. Ten alpha-dicarbonyls were quantified during beer processing and during different periods of beer aging at 28 degrees C. The aging periods were from 15 to 105 days. During beer aging, 1-deoxydiuloses were produced and degraded, while 1,4-dideoxydiuloses were produced at the highest rates. The GCO analysis indicated that forced beer aging increased the amounts of furaneol, trans-2-nonenal, and phenylacetaldehyde. The blockage of alpha-dicarbonyls inhibited the accumulation of sensory-active aldehydes in the beer headspace.

The effect of environmentally relevant conditions on PVP stabilised gold nanoparticles

Nanoparticles are a major product from the nanotechnology industry and have been shown to have a potentially large environmental exposure and hazard. In this study, sterically stabilised polyvinyl pyrrolidone (PVP) 7 nm gold nanoparticles (NPs) were produced and characterised as prepared by surface plasmon resonance (SPR), size and aggregation, morphology and surface charge. Changes in these properties with changes in environmentally relevant conditions (pH, ionic strength, Ca concentration and fulvic acid presence) were quantified. These sterically stabilised NPs showed no aggregation with changes in pH or inorganic ions, even under high (0.1 M) Ca concentrations. In addition, the presence of fulvic acid resulted in no observable changes in SPR, size, aggregation or surface chemistry, suggesting limited interaction between the PVP stabilised nanoparticles and fulvic acid. Due to the lack of aggregation and interaction, these NPs are expected to be highly mobile and potentially bioavailable in the environment.

Water-soluble gold nanoparticles stabilized with cationic phosphonium thiolate ligands

Attachment of cationic groups to the surface of gold nanoparticles (AuNPs) is an attractive proposition for facilitating mitochondria-targeted therapeutics and diagnostics. With this in mind we have prepared and characterised AuNPs functionalised with phosphonium groups derived from either triarylphosphoniopropylthiosulfate zwitterions or ω-thioacetylpropyl(triphenyl)phosphonium salts; organophosphonium cations display remarkable lipophilicity and are readily taken up by cells and are concentrated in the mitochondria. The phosphonium-functionalised AuNPs can be dispersed in water and biological media. Transmission Electron Microscopy reveals the formation of spherical particles with diameters in the range 3–5 nm. The presence of the phosphonioalkylthiolate ligands on the surface of the AuNPs is confirmed by XPS, LDI-TOF-MS, TOF-SIMS and 31P NMR spectroscopy. The phosphonium-AuNPs display excellent stability and preliminary studies indicate that the phosphonioalkylthiolate ligands are slowly oxidised over a period of months to the corresponding phosphonioalkylsulfonate species with a concomitant increase in the particle size, and particle size distribution, of the AuNPs.

Microplastic-Associated Biofilms: A Comparison of Freshwater and Marine Environments

Microplastics (<5 mm particles) occur within both engineered and natural freshwater ecosystems, including wastewater treatment plants, lakes, rivers, and estuaries. While a significant proportion of microplastic pollution is likely sequestered within freshwater environments, these habitats also constitute an important conduit of microscopic polymer particles to oceans worldwide. The quantity of aquatic microplastic waste is predicted to dramatically increase over the next decade, but the fate and biological implications of this pollution are still poorly understood. A growing body of research has aimed to characterize the formation, composition, and spatiotemporal distribution of microplastic-associated (“plastisphere”) microbial biofilms. Plastisphere microorganisms have been suggested to play significant roles in pathogen transfer, modulation of particle buoyancy, and biodegradation of plastic polymers and co-contaminants, yet investigation of these topics within freshwater environments is at a very early stage. Here, what is known about marine plastisphere assemblages is systematically compared with up-to-date findings from freshwater habitats. Through analysis of key differences and likely commonalities between environments, we discuss how an integrated view of these fields of research will enhance our knowledge of the complex behavior and ecological impacts of microplastic pollutants.

Applications to Soft Matter: general discussion

Vinothan N. Manoharan, Guruswamy Kumaraswamy, Madivala G. Basavaraj, Sanat Kumar, Siddharth Kulkarni, Ranjini Bandyopadhyay, Sudeep Punnathanam, Ajeet Srivastav, Lola Gonzalez-Garcia, G V Pavan Kumar, Daan Frenkel, Radhika Poojari, Priyadarshi Roy Chowdhury, Gourav Shrivastav, Mukta Tripathy, Vimala Sridurai, Alison Edwards, Madhura Som, B. L. V Prasad, Lynn Walker, Neena S. John, Yon Ju-Nam, Yogesh M. Joshi, Nirmalya Bachhar, Charusita Chakravarty, Rajdip Bandyopadhyaya, Zakiya Shireen, Nicholas Kotov, Oleg Gang, Alamgir Karim, Mario Tagliazucchi, Erika Eiser and Andrea Tao

Synthesis of Nanoparticle Assemblies: general discussion

Madhura Som, Sristi Majumdar, Nirmalya Bachhar, Guruswamy Kumaraswamy, G. V. Pavan Kumar, Vinothan N. Manoharan, Sanat Kumar, Madivala G. Basavaraj, Siddharth Kulkarni, Ranjini Bandyopadhyay, Sudeep Punnathanam, Himani Medhi, Ajeet Srivastav, Daan Frenkel, Mukta Tripathy, Erika Eiser, Lola Gonzalez-Garcia, Priyadarshi Roy Chowdhury, Jayant Singh, Vimala Sridurai, Alison Edwards, B. L. V. Prasad, Amit Kumar Singh, Michael Bockstaller, Neena S. John, Jyoti Seth, Mayank Misra, Charusita Chakravarty, Vandana Shinde, Rajdip Bandyopadhyaya, Jacques Jestin, Radhika Poojari, Nicholas Kotov, Oleg Gang, Alamgir Karim, Yon Ju-Nam, Steve Granick, Semen Chervinskii and Andrea Tao