title: Immobilization of enzymes to silver island films for enhanced enzymatic activity.
abstract: OBJECTIVE
  The performance of the enzyme-based biosensors depends on the enzymatic activity and the use of an appropriate technique for immobilization of enzymes. The incorporation of silver island films (SIFs) into the enzyme-based biosensors is expected to enhance the enzymatic activity and to increase the detectability of analytes of interest.
  
  
  METHODS
  Two enzymes, β-galactosidase (β-Gal) and alkaline phosphatase (AP) were immobilized onto SIFs using the interactions of avidin-modified enzymes with (i) a monolayer of biotinylated bovine serum albumin (b-BSA) and/or (ii) a monolayer of biotinylated poly(ethylene-glycol)-amine (BEA molecular weight: 550-10,000Da). To confirm the effect of SIFs on enzymatic activity, two control surfaces (no silver) were also employed.
  
  
  RESULTS
  No enhancement in enzymatic activity for β-Gal on all SIFs was observed, which was attributed to the inhibition of β-Gal activity due to direct interactions of β-Gal with SIFs. The AP activity on SIFs with BEA was significantly larger than that observed on SIFs with b-BSA, where a 300% increase in AP activity was observed as compared to control surfaces. These observations suggest that SIFs can significantly enhance AP activity, which could help improve the detection limits of ELISAs and immunoassays that employ AP.
authors.affiliation: Morgan State University, Department of Chemistry, 1700 East Cold Spring Lane, Baltimore, MD 21251, USA.
authors.forename: Biebele
authors.initials: B
authors.lastname: Abel
authors.forename: Kadir
authors.initials: K
authors.lastname: Aslan
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry*; D000818:Animals; D015374:Biosensing Techniques; D001710:Biotin / Q000737:chemistry; D002417:Cattle; D003124:Colorimetry; D057075:Enzyme Assays; D004800:Enzymes, Immobilized; D011092:Polyethylene Glycols / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D019809:Streptavidin / Q000737:chemistry; D001616:beta-Galactosidase / Q000737:chemistry
chemical_list: D004800:Enzymes, Immobilized; D012710:Serum Albumin, Bovine; D012834:Silver; D011092:Polyethylene Glycols; D001710:Biotin; D019809:Streptavidin; D000469:Alkaline Phosphatase; D001616:beta-Galactosidase
keywords: Alkaline phosphatase; Biotin-Poly (Ethylene-glycol) Amine; Enzymatic activity; Enzymes; Protein assays; Silver island films; β-galactosidase