Evaluation of the immunochromatographic strip test for the rapid diagnosis of antenatal syphilis in women in Eldoret,Kenya

Objective： This study compared the performance of the immunochromatographic strip （ICS） to the Venereal Disease Research Laboratory （VDRL） test and Treponema pallidum haemagglutination assay （TPHA） at a primary health care setting. Methods： The study group was comprised of 150 females randomly drawn from a population of pregnant women attending their first antenatal visit or follow-up visits at West Maternity Hospital in Eldoret Kenya, but without a previous syphilis test during that pregnancy. On-site VDRL, ICS and TPHA tests were performed and immediate treatment provided where appropriate. The performance of the three tests was compared, Results： The sero-prevalence of syphilis as determined by the VDRL test was 3%. There was no significant difference between the ICS and the VDRL test （P 〉 0.05）. The sensitivity and specificity of the ICS test were 80% and 98.6% respectively, while the negative predictive value （NPV） and positive predictive value （PPV） were both 100%. On the other hand, the sensitivity and specificity of the VDRL test were 66.7% and 99.3%, while the NPV and PPV were 80% and 98.6% respectively. The Treponema pallidum haemagglutination assay was used as a reference test and had sensitivity, specificity, NPV and PPV of 100%. Conclusion： The diagnostic accuracy of the ICS compared favorably with theVDRL gold standard. The use of the ICS in Kenya can improve the diagnosis of syphilis in health facilities both with and without laboratories and allow community health care workers to make a rapid diagnosis of the disease, and consequently make immediate therapeutic decisions.

Synthesis of haptens and gold-based immunochromatographic paper sensor for vitamin B_(6) in energy drinks and dietary supplements

We designed and synthesized novel haptens to produce monoclonal antibodies(mAb)against vitamin B_(6)(VB_(6)).A group-specific mAb(2F9)that recognized pyridoxine(PN),pyridoxamine(PM),and pyridoxal(PL)was prepared using a homologous strategy with 50%maximal inhibitory concentration(IC_(50))values of 106.60,250.57,and 400.11 ng/mL,respectively.Based on this,a gold nanoparticles(AuNPs)-based immunochromatographic strip(ICS)test was established for the detection of VB_(6) in energy drinks and B-vitamin complex tablets.The developed ICS test results could be semi-quantitatively evaluated by the naked eye within 10 min,and displayed the visual limit of detection(vLOD)values of 250,500,and 1,000 ng/mL for PN,PM,and PL,respectively.For quantitative analysis,the results obtained by strip reader,with calculated LOD values for PN,PM,and PL were 14.10,55.58,and 56.25 ng/mL,respectively.Commercial energy drinks and B-vitamin complex tablet samples were detected by the strips and the results were confirmed with high-performance liquid chromatography.Overall,the developed AuNPs-based immunochromatographic sensor was suitable and promising for the group-specific recognition and rapid detection of VB6 in fortified foods and dietary supplements.