Concurrent zero-dimensional and one-dimensional biomineralization of gold from a solution of Au3+ and bovine serum albumin

A technique was developed for preparing a novel material that consists of gold nanoparticles trapped within a fiber of unfolded proteins. These fibers are made in an aqueous solution that contains HAuCl4 and the protein, bovine serum albumin (BSA). By changing the ratio of gold to BSA in solution, two different types of outcomes are observed. At lower gold to BSA ratios (30-120), a purple solution results after heating the mixture at 80 °C for 4 h. At higher gold to BSA ratios (130-170), a clear solution containing purple fibers results after heating the mixture at 80 °C for 4 h. UV-Vis spectroscopy and light scattering techniques show growth in nanocolloid size as gold to BSA ratio rises above 100. Data indicate that, for the higher gold to BSA ratios, the gold is sequestered within the solid material. The material mass, visible by eye, appears to be an aggregation of smaller individual fibers. Scanning electron microscopy and transmission electron microscopy indicate that these fibers are primarily one-dimensional aggregates, which can display some branching, and can be as narrow as 400 nm in size. The likely mechanism for the synthesis of the novel material is discussed.

Circulating anodic antigen for detection of Schistosoma mansoni infection in Egyptian patients

We evaluated the ability of circulating anodic antigen (CAA) to identify infection with Schistosoma mansoni in a prospective cohort study of 257 Egyptian men, 147 with infection diagnosed by repeated Kato thick smears, and 110 without detectable infection. The CAA levels were obtained and the stool examinations were performed two weeks and one, two, four, and six months after praziquantel therapy for infected men. A CAA enzyme-linked immunosorbent assay was repeated twice on subjects who were otherwise negative for schistosomiasis. Circulating anodic antigen was detected in 117 cases, with an overall test sensitivity before treatment of 0.8. Sensitivity was related to the intensity of infection, ranging from 1.00 with > 400 eggs per gram (epg) of feces to 0.60 for those with < 100 epg. After praziquantel therapy, the level of the antigen was significantly reduced. Specificity was excellent before treatment (1.00, 95% confidence interval = 0.97-1.0), but it decreased to 0.98 four months after treatment. Likelihood ratios were significant for all titers > or = 4. We conclude that CAA has moderate sensitivity and excellent specificity when used to identify infection with schistosomiasis, as well as to monitor the results of therapy after at least one month after treatment.