Cost-effective and compact wide-field fluorescent imaging on a cell-phone.

We demonstrate wide-field fluorescent and darkfield imaging on a cell-phone with compact, light-weight and cost-effective optical components that are mechanically attached to the existing camera unit of the cell-phone. For this purpose, we used battery powered light-emitting diodes (LEDs) to pump the sample of interest from the side using butt-coupling, where the pump light was guided within the sample cuvette to uniformly excite the specimen. The fluorescent emission from the sample was then imaged using an additional lens that was positioned right in front of the existing lens of the cell-phone camera. Because the excitation occurs through guided waves that propagate perpendicular to our detection path, an inexpensive plastic colour filter was sufficient to create the dark-field background required for fluorescent imaging, without the need for a thin-film interference filter. We validate the performance of this platform by imaging various fluorescent micro-objects in 2 colours (i.e., red and green) over a large field-of-view (FOV) of ∼81 mm(2) with a raw spatial resolution of ∼20 µm. With additional digital processing of the captured cell-phone images, through the use of compressive sampling theory, we demonstrate ∼2 fold improvement in our resolving power, achieving ∼10 µm resolution without a trade-off in our FOV. Further, we also demonstrate darkfield imaging of non-fluorescent specimen using the same interface, where this time the scattered light from the objects is detected without the use of any filters. The capability of imaging a wide FOV would be exceedingly important to probe large sample volumes (e.g., >0.1 mL) of e.g., blood, urine, sputum or water, and for this end we also demonstrate fluorescent imaging of labeled white-blood cells from whole blood samples, as well as water-borne pathogenic protozoan parasites such as Giardia Lamblia cysts. Weighing only ∼28 g (∼1 ounce), this compact and cost-effective fluorescent imaging platform attached to a cell-phone could be quite useful especially for resource-limited settings, and might provide an important tool for wide-field imaging and quantification of various lab-on-a-chip assays developed for global health applications, such as monitoring of HIV+ patients for CD4 counts or viral load measurements.

Flowcytometric assessment of the effect of drugs on Giardia lamblia trophozoites in vitro.

The effect of albendazole, vincristine and metronidazole on the adherence, morphology, cell cycle and viability of Giardia lamblia trophozoites was evaluated. Albendazole rendered the trophozoites unable to attach which is a prerequisite for establishment of Giardia infection. The adherence assay showed that albendazole caused the detachment of trophozoites at a significantly lower concentration (0.1 microg/ml) as compared to metronidazole and vincristine (40 and 60 microg/ml, respectively) in the time period of 9 h. However, at the higher concentration (10 microg/ml) albendazole caused the similar effect within the time period of 3 h. The microscopic studies revealed that albendazole brought about gross morphological changes in G. lamblia, i.e., rounding of trophozoites and disruption of ventral adhesive disc along with vacuolation in cytoplasm. Metronidazole caused the ballooning of cytoplasm and induced the most lethal effect on trophozoites (8.17% viability) as compared to vincristine and albendazole (72.13 and 65.49% viability) as shown by flowcytometric analysis. Further, the flowcytometric findings indicated that the three drugs led to the arrest of growth of trophozoites at different stages of cell cycle. Albendazole and vincristine interfered with the formation of spindle/basal body microtubules thereby arresting the cell cycle in G2 + M phase whereas metronidazole arrested the growth in S-phase by inhibiting the DNA segregation and cell division. Hence, flowcytometry has been usefully employed to study the effect of drugs on viability and DNA of G. lamblia trophozoites in the present study.