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Abstract 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).

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]

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]

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]

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.

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]

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]

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]

A rapid, reliable, and sensitive method for the detection of Cronobacter sakazakii, a common foodborne pathogen that may cause serious neonatal disease, has been developed. In this study, a rapid real-time quantitative PCR (qPCR) assay combined with sodium deoxycholate (SD) and propidium monoazide (PMA) was developed to detect C. sakazakii contamination in powdered infant formula (PIF). This method could eliminate the interference from dead or injured bacteria. Optimization studies indicated that SD and PMA at 0.08% (wt/vol) and 5 μg/mL, respectively, were the most appropriate. In addition, qPCR, PMA-qPCR, SD-PMA-qPCR, and plate count assays were used to account for the number of viable bacteria in cell suspensions that were exposed to a 55°C water bath at different length of time. As a result, the viable number by PMA-qPCR showed significantly higher than of the number from SD-PMA-qPCR or plate counts. The number of viable bacteria was consistent between SD-PMA-qPCR and traditional plate counts, which indicated that SD treatment could eliminate the interference from dead or injured cells. Using the optimized parameters, the limit of detection with the SD-PMAqPCR assay was 3.3 × 102 cfu/mL and 4.4 × 102 cfu/g in pure culture and in spiked PIF, respectively. A similar detection limit of 5.6 × 102 cfu/g was obtained in the presence of the Staphylococcus aureus (107 cfu/mL). The combined SD-PMA-qPCR assay holds promise for the rapid detection of viable C. sakazakii in PIF. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a spherical, gram-positive, pathogenic bacterium commonly associated with bovine mastitis and clinical infections. It is also recognized as a pathogen that causes outbreaks of food poisoning. The objective of this study was to develop and evaluate a rapid and reliable technique that combines propidium monoazide (PMA) staining with real-time quantitative (q)PCR to detect and quantify viable cells of Staph. aureus in milk powder and meat products. The inclusivity and exclusivity of the assay were evaluated using 58 strains belonging to 14 species. Serial dilutions of Staph. aureus cells were used to establish a standard curve and to confirm the effect of PMA treatment. Milk powder and meat products were used as the spiked foods, and the ability of PMA-qPCR to eliminate nonviable cells was determined in milk powder. Furthermore, meat products were inoculated with different concentrations of Staph. aureus and 105 cfu/g of Bacillus cereus and Salmonella enterica to test the interference by nontarget microorganisms. When PMA treatment was applied before DNA extraction, we were able to eliminate false-positive results with little effect on viable cells. The PMA-qPCR assay was specific and more sensitive than conventional PCR, and the level of detection was 3.0 x 10² cfu/g in spiked milk powder. Additionally, we observed no significant interference for the detection of viable Staph. aureus from other nontarget bacteria. The PMA-qPCR protocol is an effective and rapid method to quantify viable cells of Staph. aureus in food samples. The PMA-qPCR assay is specific and reliable, offering a valuable diagnostic tool for routine analysis in food and clinical diagnostic research at a reasonable cost. [ABSTRACT FROM AUTHOR]

Titanium dioxide nanoparticles (TiO 2 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 TiO 2 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 TiO 2 NPs for 7 days decreased, while the malondialdehyde content increased and superoxide dismutase activity decreased in serum. The present study showed that TiO 2 NPs could cause reproductive toxicity. Notably, anatase is more toxic than rutile. In addition, exposure to 500 mg/kg TiO 2 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 TiO 2 NPs should be regulated., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)