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An analytical method based on single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) was developed to study the release of ZnO nanoparticles from fabric face mask samples upon washing. Before application, the method was tested with commercial ZnO nanoparticle powders suspended in various types of dispersing media, including deionized water, detergent, 20% ethanol, and pure ethanol. These dispersing media were representative simulants normally used in migration studies of nanoparticles. The commercial ZnO nanoparticle suspensions were subjected to size analysis by SP-ICP-MS, and the results were in good agreement with those analyzed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Therefore, a method based on SP-ICP-MS was applied to examine the release of ZnO nanoparticles from four commercial fabric face mask samples upon washing in deionized water and 4% detergent for five washing cycles. The total content of Zn in fabric face mask samples was found to be approximately 60–100 μg g−1, as determined by conventional ICP-MS after acid dissolution of samples. With SP-ICP-MS, the released ZnO nanoparticles from fabric face mask samples upon washing in deionized water and 4% detergent were in the range of 100–200 nm. The released percentage of Zn from mask samples was approximately 0.25–1.17% in the first washing cycle in deionized water. However, higher percentages ranging around 1.97–3.12% were found for the release of Zn from mask samples in 4% detergent. This work illustrates the capability of SP-ICP-MS for providing information that can be useful for quality control of fabric face mask products. [ABSTRACT FROM AUTHOR]

Exposure to natural rubber latex (NRL) can result in sensitivity to NRL protein with resulting allergic reactions. Low-cost, portable, simple, sensitive analytical tools for NRL protein measurements are needed for rapid and accurate assessments of allergenic risks at the point-of-care (POC) instead of using traditional methods that require large and expensive instruments, long-time analysis, and complex sample preparation steps. Here, an electrochemical paper-based analytical device (ePAD) is presented by combining sample preparation and electrochemical detection within a single device to offer a one-step NRL analysis. The lack of antibodies and/or enzymes against NRL makes POC analysis difficult. In this work, detection is based on electrochemical measurement of the remaining Cu after in situ protein complexation instead of more complex biological assays for the first time. Graphene screen-printed electrodes modified with 1,10-phenanthroline and Nafion were used in the ePAD to improve Cu signal 18-fold relative to unmodified carbon screen-printed electrodes. The optimum parameters including 1,10-phenanthroline concentration, reaction time between Cu and protein, and the starting Cu concentration were 5% w/v, 1 min, and 600 μg mL−1, respectively. In addition to short analysis time (4 min), the system selectivity indicated no other interfering species affecting protein detection. The proposed ePAD achieved an LOD of 3.0 mg dL−1 and a linear range of 10.0–200.0 mg dL−1. Finally, the proposed sensors were applied for NRL protein detection and the results were not significantly different from the traditional Lowry method at 95% confidence. [ABSTRACT FROM AUTHOR]

Flow field-flow fractionation (FlFFF) with on-line inductively coupled plasma mass spectrometer (ICP-MS) was employed to investigate the association between protein and silver nanoparticles (AgNPs). In this work, bovine serum albumin (BSA), globulin, and fibrinogen were the model proteins studied. AgNPs were prepared by the reduction of silver nitrate using tannic acid as reducing and stabilizing agent. Various sizes (2.6, 10, and 26 nm) were obtained depending on the pH condition during particle preparation. The apparent association constants between BSA and AgNPs of various sizes were determined. Then, various concentrations of 2.6 nm AgNPs were incubated with plasma proteins, i.e., albumin (2.6 × 10-1 M); globulin (3.1 × 10-2 M); and fibrinogen (2.9 × 10-3 M) at 37 °C for investigation of protein-AgNPs association. Factors influencing protein-AgNPs association were investigated, including the effect of incubation time and effect of AgNPs concentration. Association between protein and AgNPs increased as the incubation time and concentration of AgNPs increased. Further, the binding stoichiometry between BSA and AgNPs was determined to be approximately 1:5 × 10-7. [ABSTRACT FROM AUTHOR]

The hyphenated technique of field-flow fractionation (FFF) and inductively coupled plasma mass spectrometry (ICP-MS) is reviewed. FFF-ICP-MS provides unique information on elemental composition across size or molecular weight distributions. In the early stages of FFF-ICP-MS development, the technique was found to be useful for environmental applications. With the growth of nanotechnology, FFF-ICP-MS has gained increasing interest. The historical background of FFF-ICP-MS is summarized herein, including the key points reported in other previous reviews. Applications of FFF-ICP-MS are also reviewed to illustrate the potential of the technique for environmental colloids and nanoparticles. Finally, the future prospects for FFF-ICP-MS are considered. [ABSTRACT FROM AUTHOR]

This paper describes the feasibility for trace analysis of chloramphenicol using a novel immunoassay by coupling competitive measurement of chloramphenicol (CAP) to ICP-MS by the use of CAP labeled with AuNPs. Polyclonal rabbit anti-mouse immunoglobulins (anti-mouse IgG) were pre-coated on the 96-well polystyrene microplate solid support to allow the retention of mouse monoclonal to chloramphenicol (MAb-anti-CAP) antibody-CAP on the plates. Samples containing CAP as an antigen premixed with CAP–BSA protein labeled with AuNPs as an immunogenic tag were added to the MAb-anti-CAP bound solid support, physically separated from non-reacting molecules. The AuNPs were measured by ICP-MS to indirectly determine the CAP concentration in the samples. For 10 nm AuNPs, the optimal condition for CAP–BSA protein conjugation was pH 9.5 and 120 mg l−1 of CAP–BSA protein. The detection limit, linearity range, and precision (intra-assay, inter-assay) were 4.52 ng ml−1, 0–20 ng ml−1, and less than 20%, respectively. [ABSTRACT FROM AUTHOR]

Recent reports on using bio-active paper and bio-active thread to determine human blood type have shown a tremendous potential of using these low-cost materials to build bio-sensors for blood diagnosis. In this work we focus on understanding the mechanisms of red blood cell agglutination in the antibody-loaded paper. We semi-quantitatively evaluate the percentage of antibody molecules that are adsorbed on cellulose fibres and can potentially immobilize red blood cells on the fibre surface, and the percentage of the molecules that can desorb from the cellulose fibre surface into the blood sample and cause haemagglutination reaction in the bulk of a blood sample. Our results show that 34 to 42% of antibody molecules in the papers treated with commercial blood grouping antibodies can desorb from the fibre surface. When specific antibody molecules are released into the blood sample via desorption, haemagglutination reaction occurs in the blood sample. The reaction bridges the red cells in the blood sample bulk to the layer of red cells immobilized on the fibre surface by the adsorbed antibody molecules. The desorbed antibody also causes agglutinated lumps of red blood cells to form. These lumps cannot pass through the pores of the filter paper. The immobilization and filtration of agglutinated red cells give reproducible identification of positive haemagglutination reaction. Results from this study provide information for designing new bio-active paper-based devices for human blood typing with improved sensitivity and specificity.