Corrigendum to: Physicochemical insights of irradiation-enhanced hydroxyl radical generation from ZnO nanoparticles.

[This corrects the article DOI: 10.1039/c5tx00384a.].

Label-Free pH Monitoring in a Single Living Cell Using an Optical Nanoprobe.

Intracellular pH plays critical roles in cell and tissue functions during processes such as metabolism, proliferation, apoptosis, ion transportation, endocytosis, muscle contraction and so on. It is thus an important biomarker that can readily be used to monitor the physiological status of a cell. Thus, disrupted intracellular pH may serve as an early indicator of cell dysfunction and deterioration.

Unveil early-stage nanocytotoxicity by a label-free single cell pH nanoprobe.

Single-cell analysis is an emerging research area that aims to reveal delicate cellular status and underlying mechanisms by conquering the intercellular heterogeneity. Current single-cell research methods, however, are highly dependent on cell-destructive protocols and cannot sequentially display the progress of cellular events. A recently developed pH nanoprobe in our lab conceptually showed its ability to detect intracellular pH (pHi) without cell labeling or disruption.

Accurate determination of drug-to-antibody ratio of interchain cysteine-linked antibody-drug conjugates by LC-HRMS.

Accurate determination of the drug-to-antibody ratio (DAR) of interchain cysteine-linked antibody-drug conjugates (ADCs) is challenging. High-resolution mass spectrometry (HRMS) analysis of the ADCs at the intact or subunit level provides a feasible way to measure the DAR. However, the measured DAR is usually lower than the true DAR because of the variation in ionization efficiency between different DAR species.

Evaluation of statistical techniques to normalize mass spectrometry-based urinary metabolomics data.

Human urine recently became a popular medium for metabolomics biomarker discovery because its collection is non-invasive. Sometimes renal dilution of urine can be problematic in this type of urinary biomarker analysis. Currently, various normalization techniques such as creatinine ratio, osmolality, specific gravity, dry mass, urine volume, and area under the curve are used to account for the renal dilution.

Characterization of Positional Isomers of Interchain Cysteine Linked Antibody-Drug Conjugates by High-Resolution Mass Spectrometry.

Interchain cysteine linked antibody-drug conjugates (ADCs) are emerging therapeutic products that antagonize cancers. The toxic payloads are selectively linked to the interchain cysteines and generate heterogeneous mixtures of positional isomers. These positional isomers might contribute differently to the therapeutic efficacy because of the variation in conjugation stability, and thus they need to be well characterized.

Simultaneous removal of ammonia and N-nitrosamine precursors from high ammonia water by zeolite and powdered activated carbon.

When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products (DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation.

Fate of nanoparticles during alum and ferric coagulation monitored using single particle ICP-MS.

In this study, aluminum sulfate, ferric sulfate, ferric chloride, and poly(diallyldimethylammonium chloride) (pDADMAC) coagulation removal of citrate-stabilized silver and gold nanoparticles (NPs) and uncoated titanium dioxide, cerium dioxide, and zinc oxide NPs was investigated using a single particle (SP) ICP-MS direct monitoring technique. Zone 2 (charge neutralization) coagulation was performed in river water and more commonly used Zone 4 (sweep floc) coagulation was performed in both river and lake water with environmentally relevant concentrations of selected NPs added. SP-ICP-MS was used to detect NP and dissolved species, characterize the size distribution, and quantify particle concentration as well as dissolved species before and after treatments.

Evaluation of thirteen haloacetic acids and ten trihalomethanes formation by peracetic acid and chlorine drinking water disinfection.

Free chlorine is a commonly used disinfectant in drinking water treatment. However, disinfection by-products (DBPs) are formed during water disinfection. Haloacetic acids (HAAs) and trihalomethanes (THMs) are two major groups of DBPs.

Current Trends in Cancer Biomarker Discovery Using Urinary Metabolomics: Achievements and New Challenges.

Background: The development of effective screening methods for early cancer detection is one of the foremost challenges facing modern cancer research. Urinary metabolomics has recently emerged as a potentially transformative approach to cancer biomarker discovery owing to its noninvasive sampling characteristics and robust analytical feasibility.

Objective: To provide an overview of new developments in urinary metabolomics, cover the most promising aspects of hyphenated techniques in untargeted and targeted metabolomics, and to discuss technical and clinical limitations in addition to the emerging challenges in the field of urinary metabolomics and its application to cancer biomarker discovery.

Local pH Monitoring of Small Cluster of Cells using a Fiber-Optic Dual-Core Micro-Probe.

Biological studies of tissues and cells have enabled numerous discoveries, but these studies still bear potential risks of invalidation because of cell heterogeneity. Through high-accuracy techniques, recent studies have demonstrated that discrepancies do exist between the results from low-number-cell studies and cell-population-based results. Thus the urgent need to re-evaluate key principles on limited number of cells has been provoked.

Effect of oxidant demand on the release and degradation of microcystin-LR from Microcystis aeruginosa during oxidation.

In this research, the release and degradation of intracellular microcystin-LR (MC-LR) due to oxidation of Microcystis aeruginosa (M. aeruginosa) was examined kinetically. Brief exposure to free chlorine with no measureable oxidant exposure was demonstrated to be sufficient to induce rapid release of intracellular MC-LR from M.

In vitro stimulation of vascular endothelial growth factor by borate-based glass fibers under dynamic flow conditions.

Bioactive borate glass has been recognized to have both hard and soft tissue repair and regeneration capabilities through stimulating both osteogenesis and angiogenesis. However, the underlying biochemical and cellular mechanisms remain unclear. In this study, dynamic flow culturing modules were designed to simulate the micro-environment near the vascular depletion and hyperplasia area in wound-healing regions, thus to better investigate the mechanisms underlying the biocompatibility and functionality of borate-based glass materials.

Development of a high-performance liquid chromatography - Tandem mass spectrometry urinary pterinomics workflow.

Pteridines have evoked considerable interest from the scientific community owing to their prominent roles in human health and disease. The availability of analytical methodologies suitable for comprehensive pteridine profiling, termed here as "pterinomics", has been limited by inconsistent sample preparation and the exclusion of lesser studied pteridine derivatives. In response, the present study describes a new pterinomics workflow using a high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS) methodology for the simultaneous analysis of 15 pteridine derivatives including four structural isomers, marking the largest quantitative pteridine panel that has been studied to-date.

N-nitrosamine formation by monochloramine, free chlorine, and peracetic acid disinfection with presence of amine precursors in drinking water system.

In this study, the formation of eight N-nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine, N-nitrosomethylamine, N-nitrosodi-n-propylamine, N-nitrosodi-n-butylamine, N-Nitrosopiperidine, N-Nitrosopyrrolidine, N-Nitrosomorpholine, were systematically evaluated with respect to seven N-nitrosamine precursors (dimethylamine, trimethylamine, 3-(dimethylaminomethyl)indole, 4-dimethylaminoantipyrine, ethylmethylamine, diethylamine, dipropylamine) and three disinfectants (monochloramine, free chlorine, peracetic acid) under variable dosages, exposure times, and pH in a drinking water system. Without the presence of the seven selected N-nitrosamine precursors N-nitrosamine formation was not observed under any tested condition except very low levels of N-Nitrosopyrrolidine under some conditions. With selected N-nitrosamine precursors present N-nitrosamines formed at different levels under different conditions.

Detection of zinc oxide and cerium dioxide nanoparticles during drinking water treatment by rapid single particle ICP-MS methods.

Nanoparticles (NPs) entering water systems are an emerging concern as NPs are more frequently manufactured and used. Single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) methods were validated to detect Zn- and Ce-containing NPs in surface and drinking water using a short dwell time of 0.1 ms or lower, ensuring precision in single particle detection while eliminating the need for sample preparation.

Physicochemical insights of irradiation-enhanced hydroxyl radical generation from ZnO nanoparticles.

The widespread use of zinc oxide nanoparticles (ZnO NPs) has raised environmental and human health concerns owing to their significant cytotoxicity. Although their cytotoxic effects have been associated with reactive oxygen species (ROS), the physicochemical mechanism underlying this phenomenon remains poorly understood. In this study, the physicochemical properties of ZnO NPs were systematically investigated in relation to their effect on ROS generation.

Urinary metallomics as a novel biomarker discovery platform: Breast cancer as a case study.

Background: Urinary metallomics is presented here as a new "omics" approach that aims to facilitate personalized cancer screening and prevention by improving our understanding of urinary metals in disease.

Methods: Twenty-two urinary metals were examined with inductively-coupled plasma-mass spectrometry in 138 women newly diagnosed with breast cancer and benign conditions. Urinary metals from spot urine samples were adjusted to renal dilution using urine specific gravity.

Single particle ICP-MS characterization of titanium dioxide, silver, and gold nanoparticles during drinking water treatment.

One of the most direct means for human exposure to nanoparticles (NPs) released into the environment is drinking water. Therefore, it is critical to understand the occurrence and fate of NPs in drinking water systems. The objectives of this study were to develop rapid and reliable analytical methods and apply them to investigate the fate and transportation of NPs during drinking water treatments.

Biomarker analysis for oncology.

Cancer biomarkers are biological, chemical or biophysical entities that are present in tumor tissues or body fluids which give valuable information about current and future behavior of cancer. This review discusses the applicability of biomarkers in different stages of cancer from cancer risk assessment to recurrence. In medical practice, biomarkers can be helpful in finding out one's potential cancer risk, confirming whether or not one is already affected with a particular type of cancer, to which drug will the cancer respond best and in what doses should it be administered, the effectiveness of the treatment and whether the cancer will recur.

Integrated Chemical Vapor Sensor Based on Thin Wall Capillary Coupled Porous Glass Microsphere Optical Resonator.

A miniaturized chemical vapor sensor probe was developed using a porous glass microsphere (PGM) as the alignment-free optical microresonator. The porous microsphere was placed inside a thin wall silica capillary tube that was fusion-spliced to an optical fiber. The whispering gallery modes (WGMs) of the microsphere were excited by the evanescent field of the light propagating inside the capillary thin wall.

Fiber-Optic-Based Micro-Probe Using Hexagonal 1-in-6 Fiber Configuration for Intracellular Single-Cell pH Measurement.

Single-cell research is essential for understanding cell heterogeneity, cell differentiation, and carcinogenesis, among other important cellular processes. New techniques for intracellular pH monitoring are urgently needed to gain new insights into single-cell responses to external stimuli. In this study, fiber-optic reflection-based pH micro (μ)-probes (tip diameter: 500-3000 nm) were designed and fabricated using a novel hexagonal 1-in-6 fiber configuration.

In vitro study of improved wound-healing effect of bioactive borate-based glass nano-/micro-fibers.

Because of the promising wound-healing capability, bioactive glasses have been considered as one of the next generation hard- and soft-tissue regeneration materials. The lack of understanding of the substantial mechanisms, however, indicates the need for further study on cell-glass interactions to better interpret the rehabilitation capability. In the present work, three bioactive glass nano-/micro-fibers, silicate-based 45S5, borate-based 13-93B3 and 1605 (additionally doped with copper oxide and zinc oxide), were firstly compared for their in vitro soaking/conversion rate.

Simultaneous detection of perchlorate and bromate using rapid high-performance ion exchange chromatography-tandem mass spectrometry and perchlorate removal in drinking water.

Perchlorate and bromate occurrence in drinking water causes health concerns due to their effects on thyroid function and carcinogenicity, respectively. The purpose of this study was threefold: (1) to advance a sensitive method for simultaneous rapid detection of perchlorate and bromate in drinking water system, (2) to systematically study the occurrence of these two contaminants in Missouri drinking water treatment systems, and (3) to examine effective sorbents for minimizing perchlorate in drinking water. A rapid high-performance ion exchange chromatography-tandem mass spectrometry (HPIC-MS/MS) method was advanced for simultaneous detection of perchlorate and bromate in drinking water.

Reflection-mode micro-spherical fiber-optic probes for real-time and single-cell level pH sensing.

pH sensing at the single-cell level without negatively affecting living cells is very important but still a remaining issue in the biomedical studies. A 70 μm reflection-mode fiber-optic micro-pH sensor was designed and fabricated by dip-coating thin layer of organically modified aerogel onto a tapered spherical probe head. A pH sensitive fluorescent dye 2', 7'-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF) was employed and covalently bonded within the aerogel networks.