Infectious diseases of both viral and bacterial origin continue to be a health threat to millions of people in developed and underdeveloped countries. One successful treatment strategy for cases of sepsis or viral infections, such as Ebola disease and HIV, is the effective capture and removal of the pathogenic agent from the bloodstream (i.e., pathogen blood cleansing). We are presently developing filter-less technologies for the direct capture of bacteria (i.e., Escherichia coli
) and eventually viruses (i.e., Ebola virus-like-particles) from the bloodstream. We use a portable/disposable system for the continuous capture of pathogens circulating through a microfluidic chamber. The system is based on the specific recognition of proteins on E. coli
membranes; it integrates the use of (a) anti-E. coli
polyclonal antibodies, (b) magnetic nanoparticles (MNP), (c) a microfluidic chaotic flow system, and (d) a neodymium magnet. Anti-E. coli
antibodies are covalently immobilized within commercial magnetic nanoparticles to fabricate nanoparticles that will bind E. coli
bacteria. Our experiments compare the performance of different immobilization strategies (amino-carboxylic covalent binding and streptavidin-biotin binding) and different magnetic nanoparticle sizes (range 30–800 nm). The heart and distinctive feature of our system is a microfluidic chamber in which the E. coli
binding particles and the bacteria are mixed by the action of a laminar chaotic flow produced by the alternating rotation of two cylinders. The intimate contact induced by this chaotic laminar flow promotes the capture of the bacteria by individual nanoparticles or nanoparticle clusters. The trapped E. coli
are then concentrated by a simple magnet located downstream from the microchamber.
This platform has key advantages over currently available methods, which are mostly based on the use of microfluidic channels or filtering membranes: (a) It is faster (overall capture times in the order of 1–5 minutes); (b) It offers superior capture due to the intimate mixing induced by the chaotic flow; (c) It is easy to use, which reduces labor efforts and eliminates the need for dedicated and costly infrastructure.