title: Protein-mediated synthesis, pH-induced reversible agglomeration, toxicity and cellular interaction of silver nanoparticles.
abstract: Casein, a milk protein, is used to produce biotolerable and highly stable silver nanoparticles with a fair control over their size without using any additional reducing agent. These silver nanoparticles undergo reversible agglomeration to form protein-silver nanoparticle composite agglomerates as pH approaches to the isoelectric point of casein protein (pI=4.6). These agglomerates can then easily be re-dispersed in alkaline aqueous media with no obvious change in their optical properties. The nanoparticles can withstand high salt concentration (~0.5M), and can also be freeze-dried, stored as dry powder and then dispersed in aqueous media whenever required. More interestingly, by controlling the concentration of casein protein and pH, it was also possible to control the self-assembly of silver nanoparticles to produce fairly uniform spherical agglomerates. The nanoparticles and their agglomerates were thoroughly characterized using UV-visible and FTIR spectroscopy, TEM, SEM and DLS, etc. Cytotoxicity of the hybrid materials was examined using a Resazurin based cytotoxicity assay. After determining the LD(50) using NIH/3T3 fibroblast cells, the cellular interaction of these hybrid nanoparticles was studied to examine the behavior of casein-coated nanoparticles for their potential bio-applications.
authors.affiliation: National Institute for Biotechnology and Genetic Engineering (NIBGE), Jhang road, Faisalabad, Pakistan.
authors.forename: Sumaira
authors.initials: S
authors.lastname: Ashraf
authors.forename: Azhar Zahoor
authors.initials: AZ
authors.lastname: Abbasi
authors.forename: Christian
authors.initials: C
authors.lastname: Pfeiffer
authors.forename: Syed Zajif
authors.initials: SZ
authors.lastname: Hussain
authors.forename: Zafar Mahmood
authors.initials: ZM
authors.lastname: Khalid
authors.forename: Pilar Rivera
authors.initials: PR
authors.lastname: Gil
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Parak
authors.forename: Irshad
authors.initials: I
authors.lastname: Hussain
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000009:adverse effects / Q000737:chemistry*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D041681:NIH 3T3 Cells; D011506:Proteins / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D011506:Proteins; D012834:Silver