The discovery of fullerenes in 1985 has ushered in an explosive growth in the applications of engineered nanomaterials and consumer products. Nanotechnology and engineered nanomaterials (ENMs) are being incorporated into a range of commercial products such as consumer electronics, cosmetics, imaging and sensors. Nanomaterials offer new possibilities for the development of novel sensing and monitoring technologies. Nanosensors can be classified under two main categories: (i) Nanotechnology-enabled sensors or sensors that are themselves nanoscale or have nanoscale materials or components, and (ii) Nanoproperty-quantifiable sensors or sensors that are used to measure nanoscale properties. The first category can eventually result in lower material cost, reduced weight and energy consumption. The second category can enhance our understanding of the potential toxic effects of emerging pollutants from nanomaterials including fullerenes, dendrimers, and carbon nanotubes. Despite the enormous literatures and reviews on Category I sensors, there are few sensors to measure nanoscale properties or sensors belonging to Category II. This class of nanosensors is an area of critical interest to nanotoxicology, detection and risk assessment, as well as for monitoring of environmental and/or biological exposure. This article discusses emerging fields of nanotoxicology and nanomonitoring including the challenges of characterizing engineered nanomaterials and the potentials of combining existing analytical techniques with conventional cytotoxicity methods. Two case studies are provided for development of Category II nanosensors for fullerene nanoparticles and quantum dots. One highlights the uniqueness of a portable, dissolved oxygen electrochemical sensor arrays capable of detecting the ENMs as well as provide rapid nanotoxicological information. This review has shown that addressing the complex and critical issues surrounding the environmental transformation and toxicity of ENMs must be accompanied by the creation of new approaches or further developments of existing instrumentation.

A new approach for creating flexible, mechanically strong poly(amic acid) (PAA) hybrid copolymers is described. The reduction of gold salts to gold nanoparticles by PAA coupled with its copolymerization in the presence of various silanes (e.g., N-[3-(trimethoxysilyl)-propyl] aniline (TMOSPA), 3-aminopropyl-trimethoxysilane (APTMOS), dichlorodimethylsilane (DCMS), and tetramethoxysilane (TMOS)) has enabled the design of a series of polymeric films. The resulting poly(amic acid), silane, and gold (PSG) solutions were employed for the fabrication of flexible, ternary polymers with a minimum bend ratio of 3 mm using thermal desolvation and/or wet-phase inversion techniques. By controlling the composition and synthesis conditions, porous PSG films were produced that are flexible or rigid, transparent or opaque, and/or mechanically strong. (1)H NMR, (13)C NMR, and Fourier transform infrared spectroscopy (FTIR) characterization results showed that the carboxylic acid moieties were retained in the PSG copolymer. Thermal stabilities with degradation characteristics of the polymers were determined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Although structurally and morphologically different from the parent PAA, copolymerization with silanes had significantly improved the mechanical and interfacial property of the PSG class of films.

This paper provides a survey of conventional and emerging techniques that are available for characterizing engineered nanoparticles in complex matrices. Techniques that were considered include microscopy (TEM, SEM, HRTEM, DLS, SNOM), chromatography (HDC, FFF), mass spectroscopy (ICP-MS, SEC-ICP/MS, MALDI, FFF-ICP-MS), sp-ICP-MS, and electrochemical techniques. A case study is presented from the authors’ laboratories for the design of a portable nanoparticle analyzer based on tangential flow filtration and electrochemical detection (EC-TFF). EC-TFF is equipped with poly­(amic) acid membrane filter electrodes (PMFE) arrays that perform multiple functions to capture, isolate, and detect (CID) engineered nanoparticles. The application of EC-TFF is presented for the characterization of engineered nanosilver in real-world samples. A size-dependent isolation of AgNPs was achieved at varying particle sizes with over 98.5% removal efficiency. PEC-TFF AA showed an excellent performance not only for isolation at subnanometer-sized ranges but also as a platform for detection of engineered nanoparticles at low ppb levels.

Hierarchical Cu−Sn core/shell nanowire arrays were built on 3‐dimensional macroporous Ni foams through a two‐step deposition, annealing, and electroreduction treatment. Cu was electroplated on Ni foam substrates and the sample was annealed at 500 °C followed by electroreduction, producing Cu nanowires of 150 nm diameter in arrays on the skeleton of Ni foams. Sn nanoparticles of 14–80 nm were then chemically deposited on Cu nanowires in clusters and a second annealing treatment at 200 °C followed by electroreduction re‐organized the clusters into a SnxO/Sn shell of 8 nm thickness. Creating such a Sn shell on Cu nanowires suppressed faradaic efficiencies for H2 evolution from 55.7 to 10.1 % and for HCOOH formation from 13.2 to 2.0 % and enhanced CO generation from 32.0 to 90.0 % at an applied potential of −0.8 V (vs. RHE). The faradaic efficiency for CO production remained almost constant at 90.0–91.4 % with total current densities of −13.2 to −19.3 mA cm−2 between −0.8 and −1.2 V (vs. RHE).

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