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An electrochemical enzyme-linked immobilized DNA-hybridization assay for the detection of Cryptosporidium parvum in water has been developed. The target molecule was a 121-nucleotide sequence from the C. parvum heat shock protein 70 (hsp70 mRNA from U71181 gene). This analyte offers the possibility of distinguishing dead from live oocysts. The assay involves covalent attachment of a primary DNA probe via its 5'-amine-terminus to self-assembled monolayers of mercaptoundecanoic acid to a gold surface. The primary DNA probe was used to capture the target (sequence 1039-1082 of U71181 gene for the mRNA), by hybridization to a 20-base complementary sequence on the target (at sequence 1063-1082). A secondary DNA probe labeled with alkaline phosphatase (AP) was then hybridized to base sequence 1039-1062 on the target, p-Aminophenol, which is enzymatically generated by the immobilized AP from p-aminophenyl phosphate (PAPP), is detected using electrochemistry. The peak current of cyclic voltammograms from a PAPP solution, in which gold-coated silicon wafer modified with the complete assembly of the assay components was incubated, is linear with concentration of the target (5-50 [micro]g/mL, where [P.sub.1] and [P.sub.2]-AP concentrations are 50 [micro]g/mL). A detection limit of 2 [micro]g/mL (or 146 nM) of the DNA target was obtained. Cross-reactivity tests showed high selectivity for heat-shocked C. parvum. No signal was obtained for either the synthetic DNA for hsp70 of Campylobacter lari, Escherichia coli, Giardia lamblia, Salmonella typhimurium, and Listeria monocytogenes or for the products of heat-shocked whole organisms of E. coli, G. lamblia, Staphylococcus aureus, and Cryptosporidium muris.

A self-contained, microelectrochemical immunoassay on the smallest volumes reported to date (1 [micro]L for the antigen, 1 [micro]L for the secondary antibody-enzyme conjugate, and 200 nL for the electrochemically detected species) has been developed using mouse IgG as a model system in a sandwich-type enzyme-linked immunosorbant assay, which takes less than 30 min to both complete the assembly of immunoassay components onto the antibody-modified surface and detect enzymatically generated species (excluding time for electrochemical cleaning of electrodes). These studies demonstrate the advantage of the close proximity of electrodes to modified surfaces and their application in the analysis of small volumes. Using a 50 [micro]m diameter x 8 [micro]m deep cavity with individually addressable electrodes on a microfabricated chip, the primary antibody was selectively and covalently attached at a gold, recessed microdisk (RMD) at the bottom of the microcavity to the free end of SAMs of either 11-mercaptoundecanoic acid or 11-mercapto-1-undecanol using 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride. Nonspecific adsorption to the surrounding material, polyimide, of the microcavity device was eliminated. Electrochemical desorption was used to confine the immunoassay activity at the RMD. Enzymatic conversion of the substrate p-aminophenyl phosphate to p-aminophenol is detectable in less than 30 s using cyclic voltammetry at a gold, tubular nanoband electrode, which is on the wall of the microcavity and immediately adjacent to the modified RMD. A third electrode, also within the region of the microcavity, served as the pseudoreference/auxiliary electrode. Calibration curves obtained for 1-[micro]L solutions of 5-100 ng/mL of IgG and for 200 nL-solutions of 5 [micro]M to 4 mM of PA[P.sub.R] gave detection limits of 4.4 nM (6.4 ng/mL) or 880 fmol (129 pg) for PA[P.sub.R] and 56 fM (9 pg/ mL) or 56 zmol (9 fg) for IgG. It is expected that the device may be suitable for analysis with volumes down to tens of picoliters.

Titanium dioxide nanoparticles (TiO2 NPs) have been widely used in food, medical, and other fields; their reproductive toxicity has been reported in numerous studies. However, the relevant toxicity mechanism still requires further exploration. In this paper, the effect of oral exposure to 500 mg/kg TiO2 NPs (anatase and rutile) in adult male SD rats was studied over 3 and 7 days. Results showed that the total sperm count and testosterone level of 7 days of exposure in serum decreased in the experimental group. Testicular tissue lesions, such as disappearance of Leydig cells, disorder of arrangement of spermatogenic cells in the lumen of convoluted seminiferous tubules, and disorder of arrangement of germ cells, were observed. Meanwhile, the expression of steroidogenic acute regulatory (StAR; the key factors of testosterone synthesis), MAPK (ERK1/2), and phosphorylated ERK1/2 in testes of SD rats after exposure to TiO2 NPs for 7 days decreased, while the malondialdehyde content increased and superoxide dismutase activity decreased in serum. The present study showed that TiO2 NPs could cause reproductive toxicity. Notably, anatase is more toxic than rutile. In addition, exposure to 500 mg/kg TiO2 NPs for 7 days inhibited testosterone synthesis in male rat, which may be related to the reactive oxygen species (ROS)-MAPK (ERK1/2)-StAR signal pathway. Warning that the use of TiO2 NPs should be regulated. [ABSTRACT FROM AUTHOR]

The potential toxicity of Zinc oxide nanoparticles (ZnO NPs) to human beings has become a widespread concern. This study explored the reproductive toxicity and the mechanism of toxicity of ZnO NPs in early pregnant mice. The results showed that abnormal weight changes, induced inflammation, reduced level of serum sex hormones, damaged uterus, increased abortion, and abnormal development of fetus. In the uterus, the transcription levels of ZnT‐1, HO‐1, Bax, Bax/Bcl‐2, JNK, and Caspase‐3 were significantly up‐regulated while Bcl‐2, ER‐1 and PR were significantly down‐regulated. The TUNEL‐positive cells increased that were exposed to high levels of ZnO NPs. In summary, those results indicated that Zn from high levels of exposure to ZnO NPs accumulated in the uterus that could have caused the formation of ROS that led to oxidative stress, which might have activated the mitochondrial apoptotic pathway that could have caused the uterine injury which induced the observed reproductive toxicity. [ABSTRACT FROM AUTHOR]

ZnO nanoparticles (NPs) are among the most manufactured nanoparticles in the consumer products, industries, and researches. An increasing body of evidence indicated that ZnO NPs show toxicological effects in vivo. Sex differences in the toxicity of ZnO NPs are not clear, thus the aim of this study was to investigate the effects of ZnO NPs on the female and male reproductive organs (uterus, ovary and testes). ZnO NPs were orally administered to female and male mice at dosages level of 0 and 100 mg/kg body weight. The biological material was sampled 3 days after tube feeding. The results demonstrated that Zinc contents were accumulated in the reproductive organs of treated mice. Furthermore, ZnO NPs administration induced significant decrease in the testes weight, an imbalance of hematological and serum biochemical parameters in male mice. The histopathological examinations showed that structural disorder and the appearance of cell apoptosis and death in the ZnO NPs‐exposed mice. Additionally, the RT‐qPCR data indicated ZnO NPs can activate mitochondrial‐mediated signaling pathway and induce caspase depend damage that ultimately injured the uterus. In the ovary, ZnO NPs induce cell apoptosis in Shh pathway activated ovary cells, and affect the synthesis of steroidogenesis. In the testes, ZnO NPs effectively changed the expression level of genes related to oxidant stress, detox/metabolic process, and apoptosis. It was found that ZnO NPs caused more serious reproductive toxicity in the male mice than female mice. Overall, these findings indicated that ZnO NPs could induce exposure‐related risks to reproductive health, especially in those who are at the occupational level. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) have recently attracted considerable attention in the biomedical fields because of their unique and excellent optical properties. However, information on their health effects, particularly in the reproductive system, is limited. The present study focuses on the effects of intravenous injection of CdSe/ZnS QDs on the reproductive system and embryo development at various stages of pregnancy in mice. The CdSe/ZnS QDs intravenously injected in mice during pregnancy accumulated in the maternal liver, uterus and placenta. This accumulation affected the growth and development of the embryo during the early and middle stages of pregnancy. Moreover, genotoxicity to the placenta after exposure to CdSe/ZnS QDs was demonstrated by the increased expression levels of genes related to oxidative stress and apoptosis and the reduced expression levels of genes related to the nutrient and waste transportation. Alterations in the gene expression levels have hindered the transport of metabolites across the placenta, which in turn affected the ability of the fetus to obtain nutrients. [ABSTRACT FROM AUTHOR]

Circulating tumour cells (CTCs) draw significant attention as a promising biomarker for cancer prognosis, status monitoring, and metastasis diagnosis. However, the concentration of CTCs in peripheral blood is usually extremely low, thereby requiring enrichment followed by isolation of CTCs prior to detection. An immunomagnetic separation is a promising tool for CTCs enrichment. In this study, a cost‐effective magnetic separation method, based on streptavidin–biotin complexation, was developed and the effects of magnetic beads' size in CTCs capture were compared. Magnetic nanobeads which were 25 nm in diameter lead to highest capture efficiency (82.2%) compared with 150 nm magnetic beads and 1 µm microbeads. Based on the streptavidin–biotin system, 25 nm magnetic nanobeads could capture model CTCs over 80% efficiency even at concentrations as low as ∼25 cells/mL that may represent the actual level of CTCs in peripheral blood of cancer patients. Furthermore, the isolated cells remained robust and healthy showing insignificant changes in morphology and behaviour when cultured for 24 h immediately after capture and isolation. The magnetic nanobeads based on streptavidin–biotin complexation showed promise for the easy and efficient capture and isolation of healthy CTCs for further diagnosis and analysis. [ABSTRACT FROM AUTHOR]

Circulating tumour cells (CTCs) draw significant attention as a promising biomarker for cancer prognosis, status monitoring, and metastasis diagnosis. However, the concentration of CTCs in peripheral blood is usually extremely low, thereby requiring enrichment followed by isolation of CTCs prior to detection. An immunomagnetic separation is a promising tool for CTCs enrichment. In this study, a cost-effective magnetic separation method, based on streptavidin-Cbiotin complexation, was developed and the effects of magnetic beads' size in CTCs capture were compared. Magnetic nanobeads which were 25 nm in diameter lead to highest capture efficiency (82.2%) compared with 150 nm magnetic beads and 1 μm microbeads. Based on the streptavidin-Cbiotin system, 25 nm magnetic nanobeads could capture model CTCs over 80% efficiency even at concentrations as low as ¡«25 cells/mL that may represent the actual level of CTCs in peripheral blood of cancer patients. Furthermore, the isolated cells remained robust and healthy showing insignificant changes in morphology and behaviour when cultured for 24 h immediately after capture and isolation. The magnetic nanobeads based on streptavidin-Cbiotin complexation showed promise for the easy and efficient capture and isolation of healthy CTCs for further diagnosis and analysis. [ABSTRACT FROM AUTHOR]