Horse IgG (Fab'2) [HRP]

The aim of this study was to explore the epidemiology ofToxoplasma gondiiinfection in patients with colorectal cancer (CRC) in eastern China. Therefore, 287 primary CRC patients and 287 age-matched healthy control subjects were recruited to estimate the seroprevalence ofT. gondiiand identify the risk factors of infection. Enzyme-linked immunoassays were used to test for anti-T. gondiiimmunoglobulin G (IgG) and IgM antibodies. Forty-six (16%) samples were positive for anti-T. gondiiIgG antibodies in patients with CRC, compared with 26 (9.1%) in the healthy controls, a significant difference (P=0.007). By contrast, eight (2.8%) patients tested positive forT. gondiiIgM antibodies, compared with three (1.1%) in the controls, a difference that was not significant (P=0.13). Multivariable backward stepwise logistic regression analysis revealed that a rural residence (OR 2.83; 95% CI 1.15-7.01;P=0.024) and treatment with chemotherapy (OR 2.16; 95% CI 1.02-4.57;P=0.045) were risk factors forT. gondiiinfection in patients with CRC. Thus,T. gondiiinfection is serious in patients with CRC, and a rural residence and treatment with chemotherapy are independent risk factors for infection by this parasite. Therefore, medical professionals should be aware of this pathogen in patients with CRC, and the causes ofT. gondiiinfection in these patients need to be explored further.

A highly sensitive quantum dot (QD)-based western blot assay with extended dynamic range was developed. Bimodal size distribution QD (BQ) immunoprobes composed of small size single QD (7.3 nm) and big size QD nanobead (QB) (82.9 nm) were employed for fluorescent western blot immunoassay on a membrane. Small size QD immunoprobes contributed to wider dynamic range of assay, while big size QB immunoprobes provided higher detection sensitivity. This BQ-based western blot assay can achieve a wide dynamic range (from 7.8 to 4000 ng IgG) and is nearly as sensitive as commercial available ultrasensitive chemiluminescent methods, just using a simple gel imager with UV light (365 nm) excitation and red light filter (610 nm). The fluorescent signals of BQ western blot were stable for 10 min, while chemiluminescent signals faded after 1 min. Moreover, this BQ immunoprobe was utilized for the detection of housekeeping protein and specific target proteins in complex cell lysate samples. The limit of detection of housekeeping protein is 0.25 mu g of cell lysate, and the signal intensities were proportional to loading protein amount in a wide range from 0.61 to 80 mu g. We believe that this new strategy of bimodal size distribution nanoparticles can also be expanded for other functional nanoparticle-based biological assays to improve the sensitivity and extend the dynamic range.Graphical abstract