Fast detection of Candida albicans and/or bacteria in blood plasma by "sample-self-focusing" using capillary electrophoresis-laser-induced fluorescence.

Detection of microbial contamination in blood plasma is critical and necessary in different medical and research fields. Most of the current standard procedures for the detection of bacteria and fungi can be time-consuming, for example, direct inoculation methods of microbial cultures in respective growth media can take a few days to several weeks. A fast analysis method with high sensitivity output such as CE-laser-induced fluorescence becomes an attractive alternative. Previously, a spacer-injection method with the use of zwitterionic surfactant (SB3-10) as a blocking agent to negate the cells' mobility, induce aggregation and single microbial peak formation in a buffer solution was reported. Here, a fast, simple direct method for microbial detection in blood plasma without using the spacer and blocking agent is reported. To compensate for the natural electrophoretic heterogeneity of microbes, a CTAB additive was used to sweep all microbial cells towards the plasma peak where a single sharp microbial peak is formed and detected. With the use of BacLight Green bacterial stain, the microbial peak, generally, can be detected within 10 min in front of the plasma peak using capillary electrophoresis coupled with laser-induced fluorescence detection. The LOD of microbes detectable were 5 cells per injection. This technique provides a great advantage over traditional, time-consuming microbial inoculation methods.