Multi Drug resistance to bacteria is a problem since bacteria continue dividing in blood causing sepsis that cannot be controlled by antibiotics and ultimately causing death. There have been multiple methods that have been proposed. A unique method has been published in Nature that incorporates “filtering” blood to remove the bacteria.
Blood flows very rapidly through the arteries and veins – In aorta it flows at nearly 40 cm/s and slows down in capillaries to 0.03 cm/s. To capture the bacteria mechanically, many methods have been tried magnetic nanoparticles, microfluidic devices and or filtration even though the shear forces from the flow is so high that it may dislodge the captured moiety.
A group from China has created Silicon nanowires that first of all trap the bacteria in a carbon foam (10% capture) and wire matrix (40% capture) but what is unique is that they have created a nanowire that is modified with Concanavalin A (ConA). ConA binds mannose residues on the bacteria and thus the bacteria can be trapped by the adhesion but to increase the capture efficiency, their nanowires also bend in response to the binding. This enables the wires to change shape into a claw that grab bacteria.
The authors state that this is a biomimetic to the claws of a venus fly trap plant that captures the fly by closing its jaws in response.
They claim that this method increases the capture efficiency to 97% which is commendable since a massive decrease in the bacterial load might enable the immune system to catch up and remove the cause of sepsis. It is possible that a biomarker test will need to be developed to see whether the specific bacteria are expressing a mannose residue. It is possible to have a series of biomarker tests that matches a moiety expressed on the sepsis bacteria with the corresponding binding molecule on the nanowire. It remains to be seen how this method can be put into clinical practice with dialysis on very sick patients.

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