Figure 4.

Adhesin–ligand interactions can be used to enrich pathogens from complex mixtures (e.g., fecal specimens, sputa, or urine samples) to a level where they would be clean and relatively easily detectable by classical tests. (A) Most common pre-enrichment methods make use of functionalized magnetic particles such as nanoparticles or beads, which bind to pathogens present in biological samples and are afterwards separated magnetically. (B) Surfaces functionalized with chemical cross-linkers and affinity ligands are used to directly capture bacteria with high specificity from biological samples. (C) Various types of nano-topographies such as prickly or nano-patterned surfaces, or nano-claws are used to capture bacteria. They are used alone or in combination with capture ligands. (D) Separation of bacteria from blood cells using surface acoustic waves in a microfluidic device. Other separation techniques such as viscoelastic separation are also used in microfluidic devices.