Microbiology

3D printed mechanical antibacterials
Bacteria Trap
  
The video shows a representative deployable micro-trap after 3 h of incubation, containing trapped bacteria moving inside it. The movie was captured with an optical microscope (OLYMPUS CKX41) equipped with a camera (OLYMPUS SC50) and displayed in real time.​​

   
Recently the first colistin resistant strain of E. coli in a patient in the United States has been reported. This finding is particularly alarming because it shows a path for the emergence and dissemination of pan-drug resistant bacterial strands. This could lead to the end of the road for antibiotics. For this reason, limiting the use of antibiotics is mandatory as well as limiting the spread of species carrying the resistance genes in the environment. Alternative solutions not relying on drugs and chemicals to reduce the load of unwanted bacteria are therefore badly needed.​ We show a new drug-free technology to reduce the load of E. coli in liquids. This method operates with no antibiotics, chemicals or pharmaceutical substances, works at room temperature and exploits motility of bacteria. We projected deployable 3D printed micro-traps that confine E. coli in their volume by only exploiting bacteria’s own mobility. The micro-traps operate through engineered apertures that rectify bacterial swimming and direct the cells into the sequestering micro-cavities. The method opens the road to a new “pharmacology” based on 3D micro-technology and the possibility to interfere mechanically with the dynamic properties of pathogens.
    

(a) Schematic of the rectifying funnel apertures and optical microscopy image of a micro-trap, scale bar 50 μm. Red dots: bacteria emphasized from a frame of the Supplementary Video 1. (b) Computer aided design 3D model of a micro-trap rendered in semi-transparent material, similar to the one used in the experiments, cut vertically into two halves to show the internal funnel structures. The inner volume of the structures calculated from this model is 1.72 nL. (c) SEM picture of a micro-trap. Scale bar, 80 μm. (d) 3D micro-traps on glass before detachment. Top panel: SEM image; lower panel: optical image. Scale bars, respectively, 500 μm and 5 mm. (e) Suspension of micro-traps in water. Scale bar, 1 cm.