Influence of Surface Silanization on the Physicochemical Stability of Silver Nanocoatings: A Large Length Scale Assessment

We synthesized sub-100 nm biogenic protein capped silver nanoparticles (bio-AgNPs) from a yeast extract (Rhodotorula glutinis) and assessed the chemical stability of their coatings formed on various silane-modified substrates up to the millimeter length scale. Large-field (LF) X-ray imaging was used for scanning AgNPs-coated substrates (5 X 5 mm) after they were immersed in physiological PBS for hours. Striking differences were found in the amount and the structural organization of bio-AgNPs in the coatings depending on the type of surface silanization. The relative amount of bio-AgNPs in the coatings increases due to the assembly of enlarged (8-30 mu Mm(2) in area) and chemically stable agglomerates of bio-AgNPs formed on a multilayered aminosilane film (average 230 nm thickness), which was generated with the use of 3-aminopropyltrimethoxysilane (APTMS). In contrast, substantially less bio-AgNPs was found on the hydrophobic silane film generated with the use of trimethoxyphenylsilane (TMPS) and on the films generated with 3-trihydroxysilylpropylmethyl-phosphonate (THSMP) and 3-mercaptopropyltrimethoxysilane (MPTMS). As silver nanocoatings formed on APTMS films have a remarkable stability against nanoparticle lixiviation/detachment, this architecture has a great potential in several biotechnological applications that require resistant coatings of nanoparticle for acting in physiological medium/buffers and biological fluids that contain high ionic strength, especially for catalysis and sensors and as antimicrobial surfaces.