title: Self-assembled, photoluminescent peptide hydrogel as a versatile platform for enzyme-based optical biosensors.
abstract: A self-assembled peptide hydrogel consisting of Fmoc-diphenylalanine has been employed as a biosensing platform through the encapsulation of enzyme bioreceptors (e.g., glucose oxidase or horseradish peroxidase) and fluorescent reporters (e.g., CdTe and CdSe quantum dots). Enzymes and quantum dots (QDs) were physically immobilized within the hydrogel matrix in situ in a single step by simply mixing aqueous solution containing QDs and enzymes with monomeric peptide (Fmoc-diphenylalanine) solution. By using atomic force microscopy and scanning transmission electron microscopy, we observed that the self-assembled peptide hydrogel had a three-dimensional network of nanofibers (with a diameter of approximately 70-90 nm) that physically hybridized with QDs and encapsulated enzyme bioreceptors with a minimal leakage. We successfully applied the peptide hydrogel to the detection of analytes such as glucose and toxic phenolic compounds by using a photoluminescence quenching of the hybridized QDs. The Michaelis-Menten constant (K(M)) of the photoluminescent peptide hydrogel was found to be 3.12 mM (GOx for glucose) and 0.82 mM (HRP for hydroquinone), respectively, which were much lower than those of conventional gel materials. These results suggest that the peptide hydrogel is an alternative optical biosensing platform with practical advantages such as simple fabrication via self-assembly, efficient diffusion of target analytes, and high encapsulation efficiencies for fluorescent reporters and bioreceptors.
authors.affiliation: Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 335 Science Road, Daejeon 305-701, Republic of Korea.
authors.forename: Jae Hong
authors.initials: JH
authors.lastname: Kim
authors.forename: Seong Yoon
authors.initials: SY
authors.lastname: Lim
authors.forename: Dong Heon
authors.initials: DH
authors.lastname: Nam
authors.forename: Jungki
authors.initials: J
authors.lastname: Ryu
authors.forename: Sook Hee
authors.initials: SH
authors.lastname: Ku
authors.forename: Chan Beum
authors.initials: CB
authors.lastname: Park
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005947:Glucose / Q000032:analysis*; D005949:Glucose Oxidase / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry; D008163:Luminescent Measurements / Q000295:instrumentation*; D055096:Optical Devices; D010455:Peptides / Q000737:chemistry*; D010636:Phenols / Q000032:analysis*
chemical_list: D020100:Hydrogels; D010455:Peptides; D010636:Phenols; D005949:Glucose Oxidase; D006735:Horseradish Peroxidase; D005947:Glucose