•A novel SERS sensing platform for ultrasensitive determination of chloramphenicol (CAP) was demonstrated through the use of Cy5-aptamer embedded Au core-Ag shell nanostructures.•CAP can be selectively detected in a concentration range from 1 to 1000 pg mL−1 with a limit of detection as 0.19 pg mL−1.•This approach is highly adaptable to the determination of other small analysts following the same principle.In this study, we described a novel method for highly sensitive and specific detection of chloramphenicol (CAP) based on engineered “hot” Au core-Ag shell nanostructures (Au@Ag NSs). Cy5-labeled DNA aptamer was embedded between the Au and Ag layers as a signal generator and target-recognition element, to fabricate uniform Au@Ag NSs with unexpected strong and stable SERS signals. The presented CAP can specifically bind to the DNA aptamer by forming an aptamer-CAP conjugate, and cause greatly decreased SERS signals of Au@Ag NSs. By using this method, we were able to detect as low as 0.19 pg mL−1 of CAP with high selectivity, which is much lower than those previously reported biosensors. Compared with the other SERS sensors that attached a dye in the outer layer of nanoparticles, this method exhibits excellent sensitivity and has the potential to significantly improve stability and reproducibility of SERS-based detection techniques.

The objective was to investigate the effect of treatment time of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) on inactivation of spoilage bacteria, Pseudomonas fluorescens and Macrococcus caseolyticus. P. fluorescens and M. caseolyticus were isolated from spoiled chicken carcasses and suspended in liquid media in packages before the samples were treated with DBD-ACP at 55 kV for different times. Ozone concentrations in package headspace and pH changes in bacterial suspensions were measured to assess plasma formation and antimicrobial activity inside packages. Colony formation was used to indicate the inactivation efficacy. Ozone concentrations reached 1000 ppm after a 3-min treatment. pH dropped by more than 0.25 units in bacterial suspensions immediately after a 6-min treatment and 0.70 units after the 6-min treatment and 24-h storage at 4 °C. Populations of both bacteria significantly reduced as the DBD-ACP treatment time increased. The treatment for less than 1.5 min resulted in more than 1 log reductions in both bacteria, which were similar to each other. However, treatments for additional 1.5 min reduced P. fluorescens and M. caseolyticus populations by more than 4 and 2.5 log cycles, respectively. The difference in bacterial kills between the two types of bacteria extended to the 6-min treatments. Our results demonstrate that treatment times significantly affect the inactivation of spoilage bacteria by DBD-ACP system. After the treatment times are extended for more than 1.5 min, the in-package DBD-ACP treatment has more effects on Gram-negative spoilage bacteria P. fluorescens than Gram-positive spoilage bacteria M. caseolyticus.

TiO2 nanoparticles (NPs) have been demonstrated to suppress spermatogenesis in animals, while there is little data related to the biochemical dysfunctions during spermatogenesis due to exposure to TiO2 NPs. In this study, male mice have been exposed to TiO2 NPs via intragastric administration for 60 consecutive days. The findings showed that TiO2 NP exposure resulted in lesions of testis and epididymis, deductions in sperm concentration and sperm motility, and an increase of the number of abnormal sperm in mice. Furthermore, TiO2 NP exposure with 2.5, 5, or 10 mg/kgbw decreased activities of lactate dehydrogenase (−11.59% to −39.84%), sorbitol dehydrogenase (−23.56% to −57.33%), succinate dehydrogenase (−27.04% to −57.85%), glucose-6-phosphate dehydrogenase (−28.3% to −56.42%), Na+/K+-ATPase (−15.59% to −53.11%), Ca2+-ATPase (−12.44% to −55.41%), and Ca2+/Mg2+-ATPase (−28.25% to −65.72%), and elevated activities of acid phosphatase (+10.48% to +40.0%), alkaline phosphatase (+20.65% to +64.07%), and total nitric oxide synthase (+0.68- to +2.3-fold) in the testes of mice, respectively. In addition, TiO2 NP exposure caused excessive production of reactive oxygen species (+16.15% to +110.62%), and increased malondialdehyde of lipid peroxidation product (+38.96% to +118.07%), carbonyl of protein oxidative product (+20.98% to +108.1%), and 8-hydroxydeoxyguanosine of DNA oxidative product (+0.9- to +1.83-fold) in the testes, respectively. It implied that spermatogenesis suppression caused by TiO2 NP exposure may be associated with alterations of testicular marked enzymes and oxidative stress in the testes.

•A chiral-aptamer sensor was fabricated for Hg2+ ions detection based on heterogeneous nanostructures.•This method exhibited high selectivity for Hg2+ ions and a limit of detection as low as 0.2 pg mL−1.•The approach was successfully used for the detection of Hg2+ ions in tap water samples.In this study, plasmonic heteropyramids (HPs) made from two different sized gold nanoparticles (Au NPs) and five ssDNA sequences and their application for ultrasensitive detection of mercury ion (Hg2+) were demonstrated. Four ssDNA sequences were used as building blocks to form a pyramidal DNA frame, which contains a T-rich probe DNA at one vertex and three sulfhydryl groups modified with 10 nm Au NPs at the other three vertices. Another T-rich DNA sequence was modified and attached to a 25nm Au NP. In the presence of Hg2+ ions, 25 nm Au NPs hybridized with pyramidal DNA frame to build the plasmonic HPs based on T–Hg2+–T interaction, which exhibits unprecedented circular dichroism (CD) signal in the visible region. Based on this mechanism, a simple, high sensitive and selective chiroplasmonic HPs-based probe was constructed and demonstrated for Hg2+ ions detection. Under optimized conditions, Hg2+ ions could be selectively detected in a concentration range from 1 to 500 pg mL−1 with a limit of detection of 0.2 pg mL−1, which is much lower than the strictest Hg2+ safety requirement of 1 ng mL−1 in water.