Improvement upon, and expansion of, diagnostic tools for clinical infections have been increasing in recent years. The simplicity and rapidity of techniques are imperative for their adoption and widespread usage at point-of-care. The fabrication and evaluation of such a device is reported in this work. The use of a small bioreceptor array (based on lectin-carbohydrate binding) resulted in a unique response profile, which has the potential to be used for pathogen identification, as demonstrated by Principal Component Analysis (PCA). The performance of the chemiresistive device was tested with Escherichia coli K12, Enterococcus faecalis, Streptococcus mutans, and Salmonella typhi. The limits of detection, based on concanavalin A (conA) lectin as the bioreceptor, are 4.7 × 10³ cfu/mL, 25 cfu/mL, 7.4 × 10⁴ cfu/mL, and 6.3 × 10² cfu/mL. This shows that the detection of pathogenic bacteria is achieved with clinically relevant concentrations. Importantly, responses measured in spiked artificial saliva showed minimal matrix interference. Furthermore, the exploitation of the distinctive outer composition of the bacteria and selectivity of lectin-carbohydrate interactions allowed for the discrimination of bacterial infections from viral infections, which is a current and urgent need for diagnosing common clinical infections.
Keywords: CNTs; PCA; label-free detection; lectins; pathogens; point-of-care.