title: Interaction of silver nanoparticles (SNPs) with bacterial extracellular proteins (ECPs) and its adsorption isotherms and kinetics.
abstract: Indiscriminate and increased use of silver nanoparticles (SNPs) in consumer products leads to the release of it into the environment. The fate and transport of SNPs in environment remains unknown. We have studied the interaction of SNPs with extracellular protein (ECP) produced by two environmental bacterial species and the adsorption behavior in aqueous solutions. The effect of pH and salt concentrations on the adsorption was also investigated. The adsorption process was found to be dependent on surface charge (zeta potential). The capping of SNPs by ECP was confirmed by Fourier transform infrared spectroscopy and X-ray diffraction. The adsorption of ECP on SNPs was analyzed by Langmuir and Freundlich models, suggesting that the equilibrium adsorption data fitted well with Freundlich model. The equilibrium adsorption data were modeled using the pseudo-first-order and pseudo-second-order kinetic equations. The results indicated that pseudo-second-order kinetic equation would better describe the adsorption kinetics. The capping was stable at environmental pH and salt concentration. The destabilization of nanoparticles was observed at alkaline pH. The study suggests that the stabilization of nanoparticles in the environment might lead to the accumulation and transport of nanomaterials in the environment, and ultimately destabilizes the functioning of the ecosystem.
authors.affiliation: Centre for Nano-Biotechnology, School of Bio-Sciences and Technology, VIT University, Katpadi Road, Vellore 632014, Tamilnadu, India.
authors.forename: S Sudheer
authors.initials: SS
authors.lastname: Khan
authors.forename: P
authors.initials: P
authors.lastname: Srivatsan
authors.forename: N
authors.initials: N
authors.lastname: Vaishnavi
authors.forename: Amitava
authors.initials: A
authors.lastname: Mukherjee
authors.forename: N
authors.initials: N
authors.lastname: Chandrasekaran
mesh_terms: D000327:Adsorption; D001426:Bacterial Proteins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D053768:Metal Nanoparticles; D012834:Silver; D012965:Sodium Chloride / Q000032:analysis; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D012834:Silver; D012965:Sodium Chloride