Ken D. Oakes

Direct writing on paper of foldable capacitive touch pads with silver nanowire inks.

Paper-based capacitive touch pads can be fabricated utilizing high-concentration silver nanowire inks needle-printed directly onto paper substrates through a 2D programmable platform. Post deposition, silver nanowire tracks can be photonically sintered using a camera flash to reduce sheet resistance similar to thermal sintering approaches. Touch pad sensors on a variety of paper substrates can be achieved with optimized silver nanowire tracks. Rolling and folding trials, which yielded only modest changes in capacitance and no loss of function, coupled with touch pad functionality on curved surfaces, suggest sufficient flexibility and durability for paper substrate touch pads to be used in diverse applications. A simplified model to predict touch pad capacitance variation ranges with differing touch conditions was developed, with good agreement against experimental results. Such paper-based touch pads have the advantage of simple structure, easy fabrication, and fast sintering, which holds promise for numerous commercial applications including low-cost portable devices where ultrathin and lightweight features, coupled with reliable bending stability are desirable.

Promoting DNA loading on magnetic nanoparticles using a DNA condensation strategy.

Maximizing DNA loading on magnetic nanoparticles (MNPs) is crucial for their successful utilization in gene transfer, DNA isolation, and bio-analytical applications. This enhancement is typically achieved by altering particle size and surfaces as well as charge density and ionic strength. We demonstrate a novel route for promoting DNA loading on amino-modified silica-coated magnetic nanoparticles (ASMNPs) by prior condensation of elongated DNA to a compact globule before adsorption. The enhanced DNA-loading capacity, as demonstrated by a reduction in the number of ASMNPs needed to achieve complexation, was presumably due to the elimination of DNA wrapping around nanoparticles and substantially reduced electrostatic interactions of DNA with nanoparticles because the compacted DNA globule conformation decreases its exposed surface charge. The maximum loading capacity of ASMNPs for condensed DNA was 4.4 times greater than that for elongated coiled DNA, achieving the highest ever reported value of 385 μg mg(-1). Practical applications for plasmid DNA isolation from cleared lysate confirmed the reliability of the proposed method.

Forensic assessment of polycyclic aromatic hydrocarbons at the former Sydney Tar Ponds and surrounding environment using fingerprint techniques

Polycyclic aromatic hydrocarbons (PAHs) were assessed spatially and temporally within and adjacent to a former coking and steel manufacturing facility in Sydney, Nova Scotia, Canada. Concentrations of PAHs were measured in surface soils, marine and estuary sediments prior to and during remediation of the Sydney Tar Ponds (STPs) site which was contaminated by nearly a century of coking and steel production. Previous studies identified PAHs in surficial marine sediments within Sydney Harbour, which were considered to be derived from STP discharges. Numerous PAH fingerprint techniques (diagnostic ratios, principal component analysis, quantitative and qualitative analysis) were applied to soil and sediment samples from the STPs and surrounding area to identify common source apportionment of PAHs. Results indicate coal combustion (from historical residential, commercial and industrial uses) and coal handling (from historic on-site stockpiling and current coal transfer and shipment facilities) are likely the principal source of PAHs found in urban soils and marine sediments, consistent with current and historical activities near these sites. However, PAH fingerprints associated with STP sediments correlated poorly with those of urban soils and marine sediments, but were similar to coal tar, historically consistent with by-products produced by the former coking operations. This study suggests PAH contamination of Sydney Harbour sediments and urban soils is largely unrelated to historic coking operations or recent remediation of the STPs site, but rather a legacy of extensive use of coal for a variety of activities.

Prevention of doxorubicin sorptive losses in drug delivery studies using polyethylene glycol

The nonspecific sorption of hydrophobic pharmaceuticals on reaction vessel surfaces raises serious analytical challenges for their accurate quantification. Systematic error due to sorptive loss of analytes may result in significant overestimation of drug loading on nanomaterial-based Drug Delivery Systems (DDS), leading to inaccurate determinations of dosage and DDS efficiency. We evaluated sorptive losses of doxorubicin (DOX), an effective chemotherapeutic, in polystyrene based 96-well plates, and proposed a simple but effective method to prevent the nonspecific sorption of DOX using trace concentrations of polyethylene glycol (PEG). Relative to widely used proteinaceous and surfactant surface blocking agents, PEG is effective, easy to use, and does not interfere with drug loading to the DDS.

Surface interaction of doxorubicin with anatase determines its photodegradation mechanism: insights into removal of waterborne pharmaceuticals by TiO2 nanoparticles

Titanium dioxide (TiO2) nanomaterials are extensively used in environmental and energy research. However, their utility is governed by surface interactions with surrounding environments and molecules. A deep understanding of these interactions is critical for the development of advanced TiO2 applications. Herein, we systematically investigate the adsorption of doxorubicin (DOX), a highly toxic chemotherapeutic and model antibiotic pharmaceutical, onto anatase TiO2 nanoparticles and correlate the photodegradation mechanism of DOX with its surface adsorption. Compared to the photodegradation of non-adsorbed species in solution by mobile hydroxyl radicals, the adsorption-dependent surface oxidation by UV-induced holes on TiO2 is more efficient. This study underscores the importance of controlling surface adsorption within photodegradation applications via pH alteration, which would be highly relevant for photo-oxidative remediation of environmental organic pollutants with amine or carbonyl functionalities that chemisorb on titania surfaces.

Nanotechnology in Contemporary Mine Water Issues

Nanotechnology holds great promise in advancing affordable mine water treatment and remediation technologies by improving treatment efficiency and performance. Further, it promises to overcome major challenges faced by existing treatment technologies through provision of highly efficient, modular, and multifunctional processes facilitating new treatment capabilities. Such technologies could further allow economic utilization of mine water as a source of commercially viable products. This chapter provides an overview of recent and future developments in nanotechnology that would benefit contemporary mine water treatment regimes, while investigating novel abate approaches possible through the use of nanotechnology. The chapter discusses candidate nanomaterials, their advantages and limitations relative to existing processes, and the unique properties and surface-active mechanisms that enable their adoption in mine water treatment applications.