Integrated multifunctional nanoplatform for fluorescence detection and inactivation of Staphylococcus aureus.

Foodborne illness caused by Staphylococcus aureus (S. aureus) has posed a significant threat to human health. Herein, an integrated multifunctional nanoplatform was developed for fluorescence detection and inactivation of S. aureus based on cascade signal amplification coupled with single strand DNA-template copper nanoparticles (ssDNA-Cu NPs). Benefiting from reasonable design, one-step cascade signal amplification was achieved through strand displacement amplification combined with rolling circle amplification, followed by in-situ generation of copper nanoparticles. S. aureus detection could be performed through naked eye observation and microplate reader measurement of the red fluorescence signal. The multifunctional nanoplatform had satisfactory specificity and sensitivity, achieving 5.2 CFU mL-1 detection limit and successful detection of 7.3 CFU of S. aureus in spiked egg after < 5 h of enrichment. Moreover, ssDNA-Cu NPs could eliminate S. aureus to avoid secondary bacterial contamination without further treatment. Therefore, this multifunctional nanoplatform has potential application in food safety dtection.

Assessment of dermal safety of oil extracted from Periplaneta americana: acute dermal toxicity, irritation, and sensitization.

INTRODUCTION: The American cockroach (Periplaneta americana) is used in traditional Chinese medicine. Periplaneta americana (P. americana) is rich in oil that has shown potential antioxidant and antibacterial activities in vitro. OBJECTIVE: To evaluate the safety of oil extracted from P. americana by conducting acute dermal toxicity, irritation, and sensitization tests. MATERIALS AND METHODS: In an acute dermal toxicity study, adult Sprague-Dawley rats were exposed to P. americana oil (2000 mg/kg body weight) for 24 h. Clinical observations were conducted to evaluate the toxicity, behaviour, and health of the animals every day after dermal exposure for 14 days. For the dermal irritation test, the oil was applied to rabbits in single and multiple doses. Multi-dose treatment was administered once per day for 14 days. Each rabbit served as its own left- and right-side control and the rabbits' irritation reactions in local intact and damaged skin were recorded and scored. The skin sensitization study of guinea pigs with the oil was conducted for a period of 28 days. RESULTS: The acute dermal median lethal dose (LD50) of P. americana oil was > 2000 mg/kg body weight in adult rats. There was no significant difference in mean irritation scores between the negative control and oil groups. The oil caused very little or no irritation in the intact and damaged skin rabbits treated with either single or multiple doses and it was non-sensitizing to the skin of guinea pigs. CONCLUSIONS: These results suggest that P. americana oil does not produce any significant acute toxic effects and is safe for use in animal models with almost no dermal irritation or sensitization. Therefore, it presents a low risk of provoking skin reactions in humans.