Effect of Selenium Nanoparticle Size on IL-6 Detection Sensitivity in a Lateral Flow Device.

Sepsis is the body's response to an infection. Existing diagnostic testing equipment is not available in primary care settings and requires long waiting times. Lateral flow devices (LFDs) could be employed in point-of-care (POC) settings for sepsis detection; however, they currently lack the required sensitivity. Herein, LFDs are constructed using 150-310 nm sized selenium nanoparticles (SeNPs) and are compared to commercial 40 nm gold nanoparticles (AuNPs) for the detection of the sepsis biomarker interleukin-6 (IL-6). Both 310 and 150 nm SeNPs reported a lower limit of detection (LOD) than 40 nm AuNPs (0.1 ng/mL compared to 1 ng/mL), although at the cost of test line visual intensity. This is to our knowledge the first use of larger SeNPs (>100 nm) in LFDs and the first comparison of the effect of the size of SeNPs on assay sensitivity in this context. The results herein demonstrate that large SeNPs are viable alternatives to existing commercial labels, with the potential for higher sensitivity than standard 40 nm AuNPs.

Isolation and Identification of Listeria monocytogenes from Retail Meats in Beijing.

To determine the contamination of retail meats by Listeria monocytogenes in Beijing, 70 meat samples (25 pork, 10 beef, 14 lamb, and 21 chicken) were analyzed between January and March in 1990. Eight (11%) samples were positive for L. monocytogenes , and 39 (56%) samples were found to contain other Listeria spp. Seven pork and one chicken sample contained L. monocytogenes , whereas all beef and lamb were free of L. monocytogenes . Meanwhile, 15 (60%) pork, 11 (52%) chicken, 7 (70%) beef, and 6 (43%) lamb samples were positive for other Listeria spp. The eight confirmed isolates of L. monocytogenes were serologically typed. Six (5 from pork and 1 from chicken) were serotype l/2a, and the other two isolates (2 pork) were serotype l/2c and l/2b. No isolates were of serotypes 3 and 4. All positive samples for L. monocytogenes were frozen meats, and the incidence of Listeria spp. was greater for frozen samples than for fresh. Sixty of 70 samples (22 pork, 8 beef, 11 lamb, and 19 chicken) were used to compare the effectiveness of Oxford medium and Palcam medium for the isolation of L. monocytogenes from meat samples. L. monocytogenes was isolated from seven samples by Palcam medium, while five samples were positive by Oxford medium, indicating that Palcam medium was more effective for recovering L. monocytogenes than Oxford medium.