A simple device for rapid quantification of cell number from equine buccal swab samples

Biological samples are notoriously difficult to use within portable miniaturised devices, often due to complex sample matrices or variation between cellular samples. Herein we describe a device that utilises a correction based upon the total soluble cellular protein and absorbance measurements for the accurate quantification of cell number from equine buccal swabs. Hemocytometer cell counts were initially conducted to determine average mammalian and bacterial contributions (97.66% and 2.34% respectively). Secondly, cells were lysed and centrifuged before the supernatant was utilised within a Bradford's ratio metric absorbance assay using a microplate reader. A correlation coefficient of r = 0.992 was determined, indicating this method was successful in utilising total soluble cellular protein for the quantification of cell number in unknown biological samples of this type. Upon the identification of a strong linear correlation coefficient, a portable microfluidic device was developed (r = 0.983) as a highly specific platform for real time buccal cell number quantification with the ability to be used for sample correction for buccal swab samples as low as 7.28 μg mL−1 in economic downstream biological diagnostic devices.