Preparation Of M13 Bacteriophage-AgNPs Composites For Bactericidal Application And Cr³⁺Detection

M13 bacteriophage is a flexible filamentous virus with p? protein as the major capsid protein,p?,p?,p? and p? proteins on both tips.The filamentous structure and major capsid proteins facilitate its application as templates to synthesize various nanomaterials,such as fuel cells,tissue regeneration materials,nano-metal catalysts,and drug delivery carriers.In this paper,the in-situ growth of AgNPs achieved by using M13 bacteriophage as a biological reducing agent under alkaline conditions,and their application as bactericidal reagent and for the detection of Cr3+ were also thoroughly discusssed.The increasing drug-resistance of bacteria made the treatment of bacterial infections increasingly difficult.AgNPs have broad-spectrum bactericidal properties by interacting with cell walls,membrane proteins,DNA and enzymes.In this paper,M13 bacteriophage-AgNPs composites were prepared and their bactericidal property was further investigated.M13 bacteriophage-AgNPs composites were found to achieve strong bactericidal activity against both Gram-positive and negative bacteria in short time.As the concentration of the composites increased(1.4-86.4 ?g mL-1),the viability of the bacteria decreased evidently.Scanning electron microscopic(SEM)images,propidium iodide(PI)staining and reactive oxygen species(ROS)detection showed that AgNPs destroyed both cell walls and cell membranes,stimulated ROS generation and finally killed the bacteria.The SPR effect of silver nanoparticles was further used in this paper for the sensing of Cr3+.The addition of Cr3+led to the aggregation of silver nanoparticles,with the redshift of the SPR band of silver nanoparticles.A color change from light yellow to colorless can be observed by naked eye.Transmission electron microscopic(TEM)images and dynamic light scattering(DLS)results confirmed that Cr3+-induced aggregation.The ratio of the absorption at 600nm and 405 nm was used for the quantification of Cr3+.Under the optimal conditions,the linear range of this method was 0.02-0.50 ?mol L-1,along with a R2 of 0.998,a limit of detection of 14 nmol L-1(3?/k,n=11)and a RSD of 1.1%(0.20 ?mol L-1,n=7).The proposed method was specific to Cr3+,which can be applied in the analysis of Cr3+ in real water samples.