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The development of rapid and effective detection of pathogens is necessary to prevent bacterial infection. Herein, we constructed a novel polymerase chain reaction-dynamic light scattering (PCR-DLS) sensing assay for detecting Salmonella sensitively. First, the invA gene specific for Salmonella was designed with upstream and downstream primers containing oxyethylene glycol bridge blockers which could hybridize with DNA-functionalized gold nanoparticle probes (probes-AuNPs). And the probes were hybridized complementary to the trailing end of the primers, which resulted in the aggregation of AuNPs and the change of particle diameter that could be measured by DLS. The results show that the PCR-DLS assay could improve the detection sensitivity and the limit of detection (LOD) was as low as 4.0 CFU/mL in pure culture and 1.8 × 102 CFU/mL in the spiked skim milk samples, which the detection time was less than 2 h. In conclusion, this work provides a promising strategy for developing the DLS technique of detecting foodborne pathogens. [ABSTRACT FROM AUTHOR]

Featured Application: The combination of natural plant products and probiotics contribute to regulating the gut microbiota and alleviating liver damage. Epigallocatechin gallate (EGCG) is a main active ingredient in tea, but it is difficult for it to be absorbed and utilized by the body, resulting in limited bioactivity. Therefore, we explored the role of probiotics in enhancing the physiological activity of EGCG in a mice model of liver injury. Mice were methodically treated with either a single ingredient or a combination of EGCG and Lactiplantibacillus plantarum P101 (LP.P101) for 21 days, and then administrated with intraperitoneal injection of carbon tetrachloride (CCl4) on the last day. As a result, the antioxidative genes were activated and pro-inflammatory genes were suppressed, reducing the oxidative and inflammatory injury of mice, which indicated a better preventive effect of the combination of EGCG and LP.P101 than the single ingredient. Furthermore, 16S rRNA high-throughput sequencing revealed the role of gut microbiota played in liver injury mitigation. The combination of EGCG and LP.P101 increased the relative abundance of Lactobacillus, Akkermansia and other beneficial bacteria that negatively correlated with inflammation and positively correlated with antioxidation. In conclusion, the combination of EGCG and LP.P101 was more effective than the single ingredient in alleviating liver damage caused by CCl4. Altered gut microbiota may be an important cause. [ABSTRACT FROM AUTHOR]

Sensitive, simple, and rapid pathogen separation and detection methods are essential for the early diagnosis and immediate medical treatment of bacterial infections. In this study, a novel strategy based on vancomycin (Van)-modified ovalbumin (OVA) mediated magnetic nanoprobes (MBs-OVA-Van) combined with multiplex polymerase chain reaction (mPCR) was developed for efficient isolation and detection of Staphylococcus aureus (S. aureus) and Bacillus cereus (B. cereus). Van conjugated to ovalbumin coated magnetic microcarrier via strong covalent interaction. In addition, Van binds through hydrogen bonds with d-alanyl-d-alanine moieties on the surface of gram-positive bacteria cell wall. Under optimum conditions, the MBs-OVA-Van showed that the capture efficiency (CE) for S. aureus and B. cereus in PBS and juice samples were around 91%, 92% and 89%, 85%, respectively. In addition, with a mixture containing both target bacteria in PBS and juice samples, the CE for S. aureus and B. cereus were recorded at about 90%, 91% and 80%, 84%, respectively. The MBs-OVA-Van plus mPCR method applied in PBS and juice samples for both bacteria showed limits of detection at 102 CFU mL-1 in a < 3 h total assay time. The results indicated that the method holds promise for isolation and enrichment of gram-positive bacteria with S. aureus and B. cereus as models. [ABSTRACT FROM AUTHOR]

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]

In this work, we aimed to evaluate the adverse effects and the mechanism of intestinal barrier caused by titanium dioxide nanoparticles (TiO2 NPs). Here, the effects of two different dosages (300 and 1200 mg/kg) of TiO2 NPs on female mice (n = 5) were investigated. After 28‐day oral exposure, the results of Ti content were significantly increased in the ileum in comparison with the control. The histopathological structure index of the ileum was significantly changed after TiO2 NPs exposure; villi height and crypt depth were decreased and increased, respectively. Meanwhile, TiO2 NPs treatment also significantly altered the transcription levels of genes. First, the GATA‐3 and STAT‐4 were upregulation and downregulation, respectively. Second, gene expressions of the Zonula Occludens‐1, claudin (CLDN)‐12, occludin, and myosin light chain kinase were significantly upregulated, while the CLDN‐3 was decreased. Finally, the caspase‐3, caspase‐9, and caspase‐12 were upregulated. The results of TUNEL staining indicated apoptosis in the ileum. In general, TiO2 NPs treatment significantly changed the intestine physical barrier in a dose‐dependent manner. The toxicity of TiO2 NPs could be through the imbalance in the Th1/Th2. [ABSTRACT FROM AUTHOR]

A multiplex polymerase chain reaction (mPCR) with propidium monoazide (PMA) and internal amplification control (IAC) for the simultaneous detection of waterborne pathogens Salmonella spp., Pseudomonas aeruginosa, Bacillus cereus, and Escherichia coli O157:H7, was developed. This PMA-IAC-mPCR assay used four new specific primers based on the genes for invA, ecfX, cesB, and fliC, respectively. A 16S rRNA primer was chosen for IAC to eliminate false negative results. The photosensitive dye, propidium monoazide (PMA) was used to exclude signals from dead bacteria that could lead to false positive results. In pure culture, the limits of detection (LOD) were 101 CFU/ml for P. aeruginosa, 102 CFU/ml for both Salmonella spp. and E. coli O157:H7, and 103 CFU/ml for B. cereus, respectively. In addition, with a 6–8 h enrichment of all four bacteria that were combined in a mixture that was spiked in water sample matrix, the LOD was 3 CFU/ml for Salmonella spp., 7 CFU/ml for E. coli O157:H7, 10 CFU/ml for B. cereus and 2 CFU/ml for P. aeruginosa. This PMA-IAC-mPCR assay holds potential for application in the multiplex assay of waterborne pathogens. [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]

Various surface modifications of iron oxide magnetic nanoparticles (IOMNs) can improve their stability and long‐term retention time in vivo, expanding applications of biomedical fields. However, whether the long‐term retention of IOMNs coated with different surface modifications has toxic effects remains poorly understood. Here, the toxicity of IOMNs modified with polyethylene glycol (PEG), bovine serum albumin (BSA), and carboxyl group (COOH), forming PEG–IOMNs, BSA–IOMNs, and COOH–IOMNs, respectively, were evaluated in the rats. The high accumulation of PEG–IOMNs and COOH–IOMNs both in the liver and lung, and the high accumulation BSA–IOMNs in blood after 24 day recovery were observed by elemental content analysis. Except individual neutrophils in the local portal area, PEG–IOMNs can also induce cytoplasmic vacuolisation in partial liver cells by histopathological examination. Furthermore, the results of RT‐qPCR showed that PEG–IOMNs, BSA–IOMNs, and COOH–IOMNs can change the transcript levels of most genes related to iron homeostasis, mitochondria apoptosis, inflammatory response, but <2‐fold alteration. COOH–IOMNs seemed to induce normal cell apoptosis more easily than BSA–IOMNs and PEG–IOMNs. In conclusion, BSA–IOMNs had longer‐term retention time in blood. IOMNs coated with PEG and BSA can still induce side effects on the liver. [ABSTRACT FROM AUTHOR]

Various surface modifications of iron oxide magnetic nanoparticles (IOMNs) can improve their stability and long-term retention time in vivo, expanding applications of biomedical fields. However, whether the long-term retention of IOMNs coated with different surface modifications has toxic effects remains poorly understood. Here, the toxicity of IOMNs modified with polyethylene glycol (PEG), bovine serum albumin (BSA), and carboxyl group (COOH), forming PEG-IOMNs, BSA-IOMNs, and COOH-IOMNs, respectively, were evaluated in the rats. The high accumulation of PEG-IOMNs and COOH-IOMNs both in the liver and lung, and the high accumulation BSA-IOMNs in blood after 24 day recovery were observed by elemental content analysis. Except individual neutrophils in the local portal area, PEG-IOMNs can also induce cytoplasmic vacuolisation in partial liver cells by histopathological examination. Furthermore, the results of RT-qPCR showed that PEG-IOMNs, BSA-IOMNs, and COOH-IOMNs can change the transcript levels of most genes related to iron homeostasis, mitochondria apoptosis, inflammatory response, but <2-fold alteration. COOH-IOMNs seemed to induce normal cell apoptosis more easily than BSA- IOMNs and PEG-IOMNs. In conclusion, BSA-IOMNs had longer-term retention time in blood. IOMNs coated with PEG and BSA can still induce side effects on the liver. [ABSTRACT FROM AUTHOR]

Sulfo-functionalized iron oxide magnetic nanobeads were employed as an adsorbent for magnetic solid-phase extraction of benzodiazepines in beef. The analytes were determined by high performance liquid chromatography–mass spectrometry. The sulfo-functionalized iron oxide magnetic nanobeads were characterized by transmission electron microscopy and infrared spectroscopy. The optimal pH, ionic strength, volume of sulfo-functionalized iron oxide magnetic nanobeads, and elution solvent were investigated for the isolation procedure. Under the optimized conditions, the limits of detection for diazepam, oxzepam, triazolam, and chlordiazepoxide were 0.79, 0.22, 0.13, and 0.23 ng/kg, respectively. The method was employed for the determination of the analytes in beef. Compared with established methods, magnetic solid phase extraction and high-performance liquid chromatography–tandem mass spectrometry method exhibited high sensitivity, rapid separation, and low cost. [ABSTRACT FROM PUBLISHER]

Silver metals have long been known to possess antimicrobial properties. Recently, even the nanoparticle version of silver (AgNPs) has also been established as antimicrobials. In this study AgNPs were combined with extracts of the medicinal plant Chinese honeysuckle, Lonicera japonica Thunb. The antimicrobial activity of the AgNPs‐herb was tested against pathogenic Escherichia coli CMCC44113. Using different AgNPs or herb (honeysuckle water extract or HWE) ratios in the presence of a fixed concentration of E. coli CMCC44113, potencies were found to be proportional with concentrations. The antimicrobial activities of AgNPs‐HWE combo were significant enhanced, when compared with solely AgNPs or HWE. Thus, atomic force microscopic and propidium monoazide‐PCR were used to probe the damages caused by AgNPs‐HWE combo on the cell morphology and cell membrane integrity of E. coli. The mechanism of AgNPs‐HWE combo against E. coli may attribute to AgNPs leads to cell wall lysis and damages cell membrane integrity, and thus increases the penetration of HWE into the bacterium, which results in more serious damage to bacterial cells. These findings indicated that AgNPs‐herb was more potent than the AgNPs alone and holds promise for the development of nanoparticle enhanced herbal pharmaceuticals. [ABSTRACT FROM AUTHOR]

Silver metals have long been known to possess antimicrobial properties. Recently, even the nanoparticle version of silver (AgNPs) has also been established as antimicrobials. In this study AgNPs were combined with extracts of the medicinal plant Chinese honeysuckle, Lonicera japonica Thunb. The antimicrobial activity of the AgNPs-herb was tested against pathogenic Escherichia coli CMCC44113. Using different AgNPs or herb (honeysuckle water extract or HWE) ratios in the presence of a fixed concentration of E. coli CMCC44113, potencies were found to be proportional with concentrations. The antimicrobial activities of AgNPs-HWE combo were significant enhanced, when compared with solely AgNPs or HWE. Thus, atomic force microscopic and propidium monoazide-PCR were used to probe the damages caused by AgNPs-HWE combo on the cell morphology and cell membrane integrity of E. coli. The mechanism of AgNPs-HWE combo against E. coli may attribute to AgNPs leads to cell wall lysis and damages cell membrane integrity, and thus increases the penetration of HWE into the bacterium, which results in more serious damage to bacterial cells. These findings indicated that AgNPs-herb was more potent than the AgNPs alone and holds promise for the development of nanoparticle enhanced herbal pharmaceuticals. [ABSTRACT FROM AUTHOR]

Pregnant mothers are susceptible to bacterial infections, which may compromise the health of mothers and offspring. Enterococcus faecalis is a ubiquitous species found in food, restaurants, and hospitals where pregnant woman frequently become exposed to this bacterium. However, the survival, distribution, translocation, and corresponding influence of E. faecalis have not been investigated during the pregnancy period, when the mother and fetus are susceptible to bacterial infection. In this study, a fluorescing E. faecalis strain was used to track the fate of the bacterium in pregnant mice. Orally administered E. faecalis were found to survive and disseminate to all regions of the intestinal tract. It also altered the bacterial community structure by significantly decreasing the diversity of Lactobacillus species, impairing the normal structure and function of the intestinal barrier, which may contribute to the bacterial translocation into the blood, spleen, placenta, and fetus. This may affect fetal and placental growth and development. [ABSTRACT FROM AUTHOR]

An enzyme-linked immunoassay based on dual signal transduction mechanisms has been developed for detection of ovarian cancer biomarker CA125. The immunoassay uses a nanoelectrode array (NEA) chip and absorbance methods for the dual detection. The NEA is used to confirm the optical detection of CA125 that is carried out in a high-binding 96-well plate. An alkaline phosphatase (AP) enzyme was used to label the detection antibody to allow for both the optical and electrochemical detection of CA125. Two kinds of substrates were catalyzed by the AP enzyme. para-Nitrophenylphosphate (PNPP) produces chromogenic para-nitrophenol (PNP), which can be optically detected at 405 nm. para-Aminophenylphosphate (PAPP) produces electroactive para-aminophenol (PAP), which can be detected amperometrically between −0.1 and 0.3 V. The linear ranges have been determined to be 5–1000 U mL−1 and 5–1000 U mL−1 for the optical and electrochemical immunoassays, respectively. The limit of detection of the optical immunoassay is 1.3 U mL−1 and 40 U mL−1 for the optical and electrochemical methods, respectively. [ABSTRACT FROM AUTHOR]

A rapid easy-to-use trace level direct competitive enzyme-linked immunosorbent assay (dc-ELISA) detection of total residual malachite green (MG), crystal violet (CV) and their corresponding primary metabolites leucomalachite green (LMG) and leucocrystal violet (LCV) in fishery products in a single assay was developed. The monoclonal antibodies, anti-MG and anti-CV mAbs, were prepared using carboxyl-malachite green (CMG) and cationized bovine serum albumin (cBSA) conjugates as immunogen. The linear range for the quantitative detection of total MG, CV and their primary metabolites LMG and LCV was between 0.15 to 4.5 ng mL−1with a half maximal inhibitory concentration (IC50) at 0.56 ± 0.04 ng mL−1(n = 5). The anti-MG mAbs exhibited 98% cross-reactivity to CV, less than 0.1% cross-reactivity with LMG and LCV, and no cross-reactivity with chloramphenicol, enrofloxacin, sulfadiazine, and tetracycline. Application of the dc-ELISA in fish tissue samples gave a limit of detection (LOD) of 0.37 ng g−1. The improved total detection lead to a recovery of 74.60 ± 8.38% at 0.5 ng g−1and 87.47 ± 12.83% at 2.0 ng g−1that was better than existing techniques. The dc-ELISA showed total MG in 7 out of 44 field fish samples that were confirmed with LC-MS/MS. The easy-to-use, inexpensive, and rapid dc-ELISA for the detection of total MG, CV and their corresponding primary metabolites holds promise for field applications. [ABSTRACT FROM AUTHOR]

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The purpose of this study was to synthesize, characterize and tailor the surface properties of magnetic nanoparticles with biocompatible copolymer coatings and to evaluate the efficiency of the resulting nanoconjugates as magnetic resonance imaging (MRI) contrast agents for liver imaging. Magnetic nanoparticles with core diameters of 10 and 30 nm were synthesized by pyrolysis and were subsequently coated with a copolymer containing either carboxyl (SHP) or methoxy groups as termini. All four formulas, and ferumoxides (Feridex I.V.®), were individually injected intravenously into separate, normal Balb/C mice (at 2.5, 1.0 and 0.56 mg Fe kg−1), and the animals underwent T2-weighted MRI at multiple time points post injection (p.i.) to evaluate the hepatic uptake and clearance. Furthermore, we compared the abilities of the new formulas and Feridex to detect tumors in an orthotropic Huh7 tumor model. Transmission electron microscopy (TEM) revealed a narrow size distribution of both the 10 and 30 nm nanoparticles, in contrast to a wide size distribution of Feridex. MTT, apoptosis and cyclin/DNA flow cytometry assays showed that the polymer coated nanoparticles had no adverse effect on cell growth. Among all the tested formulas, including Feridex, SHP-30 showed the highest macrophage uptake at the in vitro level. In vivo MRI studies on normal mice confirmed the superiority of SHP-30 in inducing hypointensities in the liver tissue, especially at clinical dose (0.56 mg Fe kg−1) and 3 T field. SHP-30 showed better contrast-to-noise ratio than Feridex on the orthotropic Huh7 tumor model. SHP-30 was found to be an efficient contrast agent for liver MR imaging. The success of this study suggests that, by improving the synthetic approach and by tuning the surface properties of IONPs, one can arrive at better formulas than Feridex for clinical practice. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article cites a research study that determines differential expression of virulence and stress fitness genes in L. monocytogenes and B. longum, following RNA extraction and cDNA synthesis. It uses real-time PCR and found that L. monocytogenes virulence factors showed significantly downregulated expression during co-incubation of B. longum and saline. The inhibitory effects might be the result of downregulation of L. monocytogenes virulence factors during co-incubation with B. longum.

To meet the requirement of Raman probes (labels) for biocompatible applications, a synthetic approach has been developed to sandwich the Raman-probe (malachite green isothiocyanate, MGITC) molecules between the gold core and the silica shell in gold-SiO2 composite nanoparticles. The gold-MGITC-SiO2 sandwiched structure not only prevents the Raman probe from leaking out but also improves the solubility of the nanoparticles in organic solvents and in aqueous solutions even with high ionic strength. To amplify the Raman signal, three types of core, gold nanospheres, nanorods and nanostars, have been chosen as the substrates of the Raman probe. The effect of the core shape on the surface-enhanced Raman scattering (SERS) has been investigated. The colloidal nanostars showed the highest SERS enhancement factor while the nanospheres possessed the lowest SERS activity under excitation with 532 and 785 nm lasers. Three-dimensional finite-difference time domain (FDTD) simulation showed significant differences in the local electromagnetic field distributions surrounding the nanospheres, nanorods, and nanostars, which were induced by the localized surface plasmon resonance (LSPR). The electromagnetic field was enhanced remarkably around the two ends of the nanorods and around the sharp tips of the nanostars. This local electromagnetic enhancement made the dominant contribution to the SERS enhancement. Both the experiments and the simulation revealed the order nanostars > nanorods > nanospheres in terms of the enhancement factor. Finally, the biological application of the nanostar-MGITC-SiO2 nanoparticles has been demonstrated in the monitoring of DNA hybridization. In short, the gold-MGITC-SiO2 sandwiched nanoparticles can be used as a Raman probe that features high sensitivity, good water solubility and stability, low-background fluorescence, and the absence of photobleaching for future biological applications. [ABSTRACT FROM AUTHOR]

We report in this article the microwave synthesis of relatively monodisperse, highly crystalline CdSe quantum dots (QDs) overcoated with Cd0.5Zn0.5S/ZnS multishells. The as-prepared QDs exhibited narrow photoluminescence bandwidth as the consequence of homogeneous size distribution and uniform crystallinity, which was confirmed by transmission electron microscopy. A high photoluminescence quantum yield up to 80% was measured for the core/multishell nanocrystals. Finally, the resulting CdSe/Cd0.5Zn0.5S/ZnS core/multishell QDs have been successfully applied to the labeling and imaging of breast cancer cells (SK-BR3). [ABSTRACT FROM AUTHOR]

Picogram levels of antibodies against the protective antigen (PA) of Bacillus anthracis were detected in an automated electrochemical sandwich-type enzyme-linked immunosorbant assay. The antibodies were captured and detected using an 8 × 3 array of 50-μm-diameter cavities. The reagent and sample volumes were as low as 200 nL in a less than 25-min assay from capture to signal generation. The electrochemical detection of the antibodies was demonstrated at 0.05–10 μg/mL containing only 10–5,000 pg antibodies. The limit of detection is 10 fg for a 200-nL sample. Detection of anti-PA immunoglobulin G performed in spiked normal human serum and fresh whole human blood did not show a significant difference from detection in a buffer. The initial automation of the assay involved the use of a digital syringe pump for the delivery of reagents to the capture surface. [ABSTRACT FROM AUTHOR]

The article outlines the benefits of miniaturized amperometric electrochemical systems and their applicability in DNA/RNA assays. Emphasizing recent applications for micro-organisms, the advantages offered by miniatured electrochemical methods over the spectroscopic analyses are discussed. Information on how the diminishing size of detecting electrode improves oligonucleotides detection and molecular recognition techniques is presented.

Detecting and enumerating fecal coliforms, especially Escherichia coli, as indicators of fecal contamination, are essential for the quality control of supplied and recreational waters. We have developed a sensitive, inexpensive, and small-volume amperometric detection method for E. coli β-galactosidase by bead-based immunoassay. The technique uses biotin-labeled capture antibodies (Ab) immobilized on paramagnetic microbeads that have been functionalized with streptavidin (bead–Ab). The bead–Ab conjugate captures E. coli from solution. The captured E. coli is incubated in Luria Bertani (LB) broth medium with the added inducer isopropyl β- D-thiogalactopyranoside (IPTG). The induced β-galactosidase converts p-aminophenyl β- D-galactopyranoside (PAPG) into p-aminophenol (PAP), which is measured by amperometry using a gold rotating disc electrode. A good linear correlation ( R2=0.989) was obtained between log cfu mL−1 E. coli and the time necessary to product a specific concentration of PAP. Amperometric detection enabled determination of 2×106 cfu mL−1 E. coli within a 30 min incubation period, and the total analysis time was less than 1 h. It was also possible to determine as few as 20 cfu mL−1 E. coli under optimized conditions within 6–7 h. This process may be easily adapted as an automated portable bioanalytical device for the rapid detection of live E. coli. [ABSTRACT FROM AUTHOR]

An immunoassay has been developed for the detection of the ovarian cancer biomarker CA-125 by utilizing the chemiluminescence resonance energy transfer to graphene quantum dots. This biosensor shows a wide linear range from 0.1 U mL−1 to 600 U mL−1 with a limit of detection of 0.05 U mL−1 for CA-125 in a buffer solution. [ABSTRACT FROM AUTHOR]

ZnO NPs have been assessed to show adverse effects on reproductive organs, but the molecular mechanisms of reproductive toxicity have not been sufficiently studied. In this research, the dosage effects from the oral exposure of ZnO NPs (30 nm) to pregnant mice in gestation day 10.5 to 17.5 was analyzed. Pregnant mice exposed to ZnO NPs induced dam injury, mice fetal growth restriction, and the fetus number decreased. The pathological evaluation showed that ZnO NPs exposure caused placental spongiotrophoblast area decease and structural damage. The RT-qPCR and immunocytochemistry data indicated that ZnO NPs could induce placenta oxide stress, endoplasmic reticulum stress responses, apoptosis, and altered placental function. These findings indicated that ZnO NPs could induce dam injury and fetal growth restriction. Reproductive toxicity of ZnO NPs may be due to placental injury and function alteration caused by apoptosis, oxide stress, and endoplasmic reticulum stress after ZnO NPs exposure. [ABSTRACT FROM AUTHOR]

The toxicity, especially the transgenerational toxicity of quantum dots (QDs) in vivo, is still scarcely understood in spite of great promising applications of QDs in biomedicine. In this study, the maternal status, pregnancy outcome, and fetus development of parental generation (P0) to offspring in three generations (F3) were investigated after Kunming mice perinatal (GD 13-PND 5) exposure to Cd containing QDs (CdSe/ZnS QDs) and CdCl2. The results show CdSe/ZnS QDs induced placenta injuries in P0 and diminished placenta diameters in F1 and F2. Bodyweight growth decreased in the CdSe/ZnS QDs treatment group in the F1 and F2 generation. Additionally, CdSe/ZnS QDs significantly altered the expression of key genes in the Shh signal pathway. Overall, this study exhibited that the CdSe/ZnS QDs exposure during perinatal period impaired placenta growth in the first two generations, but not on the third generation. The toxicological actions of the CdSe/ZnS QDs might be through the effects on the Shh signal pathway. [ABSTRACT FROM AUTHOR]