Combining passive sampling and toxicity testing for evaluation of mixtures of polar organic chemicals in sewage treatment plant effluent

Effluent from sewage treatment plants has been associated with a range of pollutant effects. Depending on the influent composition and treatment processes the effluent may contain a myriad of different chemicals which makes monitoring very complex. In this study we aimed to monitor relatively polar organic pollutant mixtures using a combination of passive sampling techniques and a set of biochemistry based assays covering acute bacterial toxicity (Microtox™), phytotoxicity (Max-I-PAM assay) and genotoxicity (umuC assay). The study showed that all of the assays were able to detect effects in the samples and allowed a comparison of the two plants as well as a comparison between the two sampling periods. Distinct improvements in water quality were observed in one of the plants as result of an upgrade to a UV disinfection system, which improved from 24× sample enrichment required to induce a 50% response in the Microtox™ assay to 84×, from 30× sample enrichment to induce a 50% reduction in photosynthetic yield to 125×, and the genotoxicity observed in the first sampling period was eliminated. Thus we propose that biochemical assay techniques in combination with time integrated passive sampling can substantially contribute to the monitoring of polar organic toxicants in STP effluents.

Influence of polymorphisms of the human glutathione transferases and cytochrome P450 2E1 enzyme on the metabolism and toxicity of ethylene oxide and acrylonitrile

A cohort of 59 persons with industrial handling of low levels of acrylonitrile is being studied as part of a medical surveillance programme. Previously, an extended haemoglobin adduct monitoring (N-(cyanoethyl)valine and N-(hydroxyethyl)-valine) was performed regarding the glutathione transferases hGSTM1 and hGSTT1 polymorphisms but no influence of hGSTM1 or hGSTT1 polymorphisms on specific adduct levels was found. A compilation of case reports of human accidental poisonings had pointed to significant individual differences in human acrylonitrile metabolism and toxicity. Therefore, a re-evaluation of the industrial cohort included known polymorphisms of the glutathione transferases hGSTM3 and hGSTP1 as well as of the cytochrome P450 CYP2E1. A detailed statistical analysis revealed that exposed carriers of the allelic variants of hGSTP1, hGSTP1*B/hGSTP1*C, characterized by a single nucleotide polymorphism at nucleotide 313 which results in a change from Ile to Val at codon 104, had higher levels of the acrylonitrile-specific haemoglobin adduct N-(cyanoethyl)valine compared to the carriers of the codon 113 alleles hGSTP1*A and hGSTP1*D. The single nucleotide polymorphism at codon 113 of hGSTP1 (hGSTP1*A/hGSTP1*B versus hGSTP1*C/hGSTP1*D) did not show an effect, and also no influence was seen on specific haemoglobin adduct levels of the polymorphisms of hGSTM3 or CYP2E1. The data, therefore, point to a possible influence of a human enzyme polymorphism of the GSTP1 gene at codon 104 on the detoxication of acrylonitrile which calls for experimental toxicological investigation. The study also confirmed the impact of GSTT1 polymorphism on background N-(hydroxyethyl)-valine adduct levels in haemoglobin which are caused by endogenous ethylene oxide.

Species differences in acrylonitrile metabolism and toxicity between experimental animals and humans based on observations in human accidental poisonings

The high acute toxicity of acrylonitrile may be a result of its intrinsic biological reactivity or of its metabolite cyanide. Intravenous N-acetylcysteine has been recommended for treatment of accidental intoxications in acrylonitrile workers, but such recommendations vary internationally. Acrylonitrile is metabolized in humans and experimental animals via two competing pathways; the glutathione-dependent pathway is considered to represent an avenue of detoxication whilst the oxidative pathway leads to a genotoxic epoxide, cyanoethylene oxide, and to elimination of cyanide. Cases of acute acrylonitrile overexposure or intoxication have occurred within persons having industrial contact with acrylonitrile; the route of exposure was by inhalation and/or by skin contact. The combined observations lead to the conclusion of a much higher impact of the oxidative metabolism of acrylonitrile in humans than in rodents. This is confirmed by differences in the clinical picture of acute life-threatening intoxications in both species, as well as by differential efficacies of antidotes. A combination of N-acetylcysteine with sodium thiosulfate seems an appropriate measure for antidote therapy of acute acrylonitrile intoxications. Clinical observations also highlight the practical importance of human individual susceptibility differences. Furthermore, differential adduct monitoring, assessing protein adducts with different rates of decay, enables the development of more elaborated biological monitoring strategies for the surveillance of workers with potential acrylonitrile contact.

Synthesis and toxicological evaluation of a chitosan‑L‑leucine conjugate for pulmonary drug delivery applications

Herein are reported the synthesis of a conjugate of chitosan with L-leucine, the preparation of nanoparticles from both chitosan and the conjugate for use in pulmonary drug delivery, and the in vitro evaluation of toxicity and inflammatory effects of both the polymers and their nanoparticles on the bronchial epithelial cell line, BEAS-2B. The nanoparticles, successfully prepared both from chitosan and the conjugate, had a diameter in the range of 10−30 nm. The polymers and their nanoparticles were tested for their effects on cell viability by MTT assay, on trans-epithelial permeability by using sodium fluorescein as a fluid phase marker, and on IL-8 secretion by ELISA. The conjugate nanoparticles had a low overall toxicity (IC50 = 2 mg/mL following 48 h exposure; no induction of IL-8 release at 0.5 mg/mL concentration), suggesting that they may be safe for pulmonary drug delivery applications.

PSMA-targeting iron oxide magnetic nanoparticles enhance MRI of preclinical prostate cancer

Aim Evaluate potential of newly-developed, biocompatible iron oxide magnetic nanoparticles (MNPs) conjugated with J591, an antibody to an extracellular epitope of prostate specific membrane antigen (PSMA), to enhance MRI of prostate cancer (PCa). Materials & Methods Specific binding to PSMA by J591-MNP was investigated in vitro. MRI studies were performed on orthotopic tumor-bearing NOD.SCID mice 2h and 24hr after intravenous injection of J591-MNPs, or non-targeting MNPs. Results and Conclusions In vitro, MNPs did not affect PCa cell viability, and conjugation to J591 did not compromise antibody specificity and enhanced cellular iron uptake. In vivo, PSMA-targeting MNPs increased MR contrast of tumors, but not by non-targeting MNPs. This provides proof-of-concept that PSMA-targeting MNPs have potential to enhance MR detection/localization of PCa.,

Development and characterization of a novel, antimicrobial, sterile hydrogel dressing for burn wounds : single-step production with gamma irradiation creates silver nanoparticles and radical polymerization

Patients with burn wounds are susceptible to wound infection and sepsis. This research introduces a novel burn wound dressing that contains silver nanoparticles (SNPs) to treat infection in a 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na(+) ) hydrogel. Silver nitrate was dissolved in AMPS-Na(+) solution and then exposed to gamma irradiation to form SNP-infused hydrogels. The gamma irradiation results in a cross-linked polymeric network of sterile hydrogel dressing and a reduction of silver ions to form SNPs infused in the hydrogel in a one-step process. About 80% of the total silver was released from the hydrogels after 72 h immersion in simulated body fluid solution; therefore, they could be used on wounds for up to 3 days. All the hydrogels were found to be nontoxic to normal human dermal fibroblast cells. The silver-loaded hydrogels had good inhibitory action against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Results from a pilot study on a porcine burn model showed that the 5-mM silver hydrogel was efficient at preventing bacterial colonization of wounds, and the results were comparable to the commercially available silver dressings (Acticoat(TM) , PolyMem Silver(®) ). These results support its use as a potential burn wound dressing.

Regenerative silver nanoparticles for SERRS investigation of metmyoglobin with conserved heme pocket

Shell isolated silver nanoparticles with an ultrathin silica layer (Ag@SiO2NPs) are used as a surface-enhanced resonance Raman scattering (SERRS) substrate for probing metmyoglobin (metMb) in aqueous solution. The ultrathin silica layer protects metMb from reaching the bare silver surface and conserves the heme pocket during SERRS analysis with a Raman enhancement factor (EFSERS) of 4.78 × 104. In spite of the good SERRS enhancement, the interaction between the protein and Ag@SiO2NPs is weak enough to separate them by centrifugation in such a way that both are regenerated in their original form and can be reused. Using Ag@SiO2NPs as the SERRS substrate, the lowest detection limit of 2 nM was achieved for metMb whilst conserving the native structure of the heme centre.

Complementary surface-enhanced resonance raman spectroscopic biodetection of mixed protein solutions by chitosan- and silica-coated plasmon-tuned silver nanoparticles

Silver nanoparticles with identical plasmonic properties but different surface functionalities are synthesized and tested as chemically selective surface-enhanced resonance Raman (SERR) amplifiers in a two-component protein solution. The surface plasmon resonances of the particles are tuned to 413 nm to match the molecular resonance of protein heme cofactors. Biocompatible functionalization of the nanoparticles with a thin film of chitosan yields selective SERR enhancement of the anionic protein cytochrome b5, whereas functionalization with SiO2 amplifies only the spectra of the cationic protein cytochrome c. As a result, subsequent addition of the two differently functionalized particles yields complementary information on the same mixed protein sample solution. Finally, the applicability of chitosan-coated Ag nanoparticles for protein separation was tested by in situ resonance Raman spectroscopy.

Tailored silica coated Ag nanoparticles for non-invasive surface enhanced Raman spectroscopy of biomolecular targets

Silica coated Ag nanoparticles with defined surface plasmon resonances are used to selectively detect and analyze protein cofactors in solution and on interfaces via surface enhanced resonance Raman spectroscopy. The silica coating has a surprisingly small effect on optical amplification but minimizes unwanted interactions between the protein and the nanoparticle.

Functionalized Ag nanoparticles with tunable optical properties for selective protein analysis

We present a preparation procedure for small sized biocompatibly coated Ag nanoparticles with tunable surface plasmon resonances. The conditions were optimised with respect to the resonance Raman signal enhancement of heme proteins and to the preservation of the native protein structure....

Gold nanoparticles modified electrodes for biosensors

Biomolecules are chemical compounds found in living organisms which are the building blocks of life and perform important functions. Fluctuation from the normal concentration of these biomolecules in living system leads to several disorders. Thus the exact determination of them in human fluids is essential in the clinical point of view. High performance liquid chromatography, flow injection analysis, capillary electrophoresis, fluorimetry, spectrophotometry, electrochemical and chemiluminescence techniques were usually used for the determination of biologically important molecules. Among these techniques, electrochemical determination of biomolecules has several advantages over other methods viz., simplicity, selectivity and sensitivity. In the past two decades, electrodes modified with polymer films, self-assembled monolayers containing different functional groups and carbon paste have been used as electrochemical sensors. But in recent years, nanomaterials based electrochemical sensors play an important role in the improvement of public health because of its rapid detection, high sensitivity and specificity in clinical diagnostics. To date gold nanoparticles (AuNPs) have received arousing attention mainly due to their fascinating electronic and optical properties as a consequence of their reduced dimensions. These unique properties of AuNPs make them as an ideal candidate for the immobilization of enzymes for biosensing. Further, the electrochemical properties of AuNPs reveal that they exhibit interesting properties by enhancing the electrode conductivity, facilitating electron transfer and improving the detection limit of biomolecules. In this chapter, we summarized the different strategies used for the attachment of AuNPs on electrode surfaces and highlighted the electrochemical determination of glucose, ascorbic acid (AA), uric acid (UA) and dopamine derivatives using the AuNPs modified electrodes.