Nanomechanicalanalysis Of Drug-resistant Foodborne Bacteriaand The Fabrication Of Antibacterial Biointerface

Antibiotics have revolutionized the treatment of infectious disease but have also rapidly selected for the emergence of resistant pathogens.Traditional methods of antibiotic discovery have failed to keep pace with the evolution of this resistance,which suggests that new strategies to combat bacterial infections may be required.Recently,everal classes of antimicrobial nanoparticles?NPs?and nanosized carriers for antibiotics delivery have been of tremendous interest in overcoming resistance that is developed by several pathogenic microorganisms against most of the commonly used antibiotics.However,Metal nanoparticles can induce cell death,yet the toxicity effect is typically nonspecific.Herein,we report on the associated bacteria stiffness?elasticity?of pathologically defined multidrug resistant?MDR?bacteria using liquid atomic force microscopy?AFM?.Based on this softer nanomechanical property of MDR Salmonella,we designed three-dimensional nano-biointerface as a new platform for guiding bacteria fate.Unlike the conventional antibiotics,the antibacterial nano-biointerface enable to specific kill MDR Salmonella without producing multidrug resistance and the help of power equipment.In details,the results of the study are as following:?1?Nanomechnical analysis of foodborne multidrug resistant SalmonellaPrior to AFM test,the multidrug resistance of 5 Salmonella isolates was identified used by minimum inhibitory concentrations?MICs?to confirm the selected bacteria populations actually represent normal?7 and 12?and MDR bacteria?44,79 and 83?.In order to acquire the high resolution picture of bacteria under physiological buffer conditions,the bacteria were immobilized on a glass surface treated with poly-l-lysine?PLL?by electrostatic interactions.By using a multiparametric PeakForce tapping AFM,a representative normal bacterium?Salmonella 7 and 12 isolates?exhibits a unimodal stiffness distribution with one prominent peak at 3.31±0.79 MPa and 4.29±0.86 MPa,respectively.However,the average cell stiffness for the MDR bacteria?Salmonella 44,79 and 83 isolates?expressed a significantly decreased average cellular elasticity,with a value of 0.58±0.13 MPa,0.40±0.16 MPa and 0.48±0.11MPa,respectively.It is quite intriguing to note that the cell stiffness of MDR bacteria is at almost 10 times softer than the normal bacteria when compared to samples collected from the same bacterial strain.This softening phenomenon may be attributed to two reasons:overexpression of efflux pumps and alterations in in the outer membrane protein and lipopolysaccharide profiles.?2?Fabrication and anti-MDR property of nano-biointerfaceThe densely packed NiCo?OH?₂CO₃ nanowires arrays grown on FTO were prepared by a simple hydrothermal synthesis method.The obtained NiCo?OH?₂CO₃ nanoswires possessed featuring needle-like shape with a length of 5±0.5?m,a root diameter of 160±10 nm,and a head diameter of 30±15 nm.The crystallographic structure of the nanowires was investigated with X-ray diffraction?XRD?,as well as the high-resolution TEM?HRTEM?and the corresponding selected-area electron diffraction?SAED?pattern,all of which conforming to the single-crystalline structure of NiCo?OH?₂CO₃ nanowires.The original NiCo?OH?₂CO₃nanowires can be easily changed to various nanowiress with increasing head diameters precisely controlled by aqua regia etching time.Bacteria-binding molecules?Con A?were introduced onto the prepared substrates through sequential chemical covalent coupling to confer the capability for selective bacterial recognition.This nano-biointerface is reported for efficient bacterial capture and elimination based on the synergistic effect of the nanotopography and surface chemistry of the substrate on bacterial attachment and adhesion.The softer MDR Salmonella are prone to adhering on the surface of nano-biointerface and can be effectively killed?95%?when the top diameter of NiCo?OH?₂CO₃ nanowires exhibited 5nm.With the top diameter of NiCo?OH?₂CO₃ nanowires increasing,the bacterial membrane was not readily ruptured.