Figure 5
Detection of pTopI using a pump-free extraction method. (A) Schematic illustration of the microfluidic device used for pump-driven (top panel) and pump-free (lower panel) extraction of pTopI from saliva from Plasmodium infected individuals. In the case of pump-driven droplet microfluidics, patient sample, S1, and lysis buffer are fed into the microfluidic chip through the 3 inlets. By competition with oil (fed into the system through a 4th inlet) pL sized water in-oil-droplets are generated. The droplets are then led through a serpentine channel and collected. In the case of pump-free extraction, water-in-oil droplets are made by vortexing saliva, lysis buffer, S1, and oil. The droplets are then loaded into the microfluidic device using a handheld syringe and collected from the outlet after passage through a serpentine channel. (B) Extraction of saliva from uninfected or Plasmodium infected individuals was done using the pump-free microfluidics method depicted in A). The boxplot represents the results of testing two samples from uninfected persons and two samples from persons with malaria (patients #4 and #32, see Table 2). The results shown represent the results of three independent extractions of each sample. The results were normalized to the results obtained using a sample from patient #12 (Table 2) as reference sample (C) Left panel; representative image of the results obtained when combining pump-free microfluidics with the colorimetric read-out described in Fig. 4. The figure shows a filter after completion of the assay using a sample from an uninfected individual and a sample from a plasmodium infected individual (patient #33, see Table 2). Right panel; quantitative depiction of the result obtained when testing 6 samples using the pump-free extraction combined with colorimetric readout. The results are shown as fold-increase over the average of the readings obtained when testing negative samples. Hence, the negative samples give numbers varying around 1.
