title: Diatom-based label-free optical biosensor for biomolecules.
abstract: Diatoms are unicellular algae, which fabricates ornate biosilica shells called frustules that possess a surface rich in reactive silanol (Si-OH) groups. The intrinsic patterned porous structure of diatom frustules at nanoscale can be exploited in the effective detection of biomolecules. In this study, the frustules of a specific diatom Amphora sp. has been functionalized to detect bovine serum albumin (BSA). The functionalization of the diatom frustule substrate is achieved by using 3-aminopropyltriethoxysilane (APES). The field emission scanning electron microscopy (FESEM) results showed an ornately patterned surface of the frustule valve ordered at nanoscale. The Fourier transform infrared (FTIR) spectra confirmed the N-H bending and stretching of the amine group after amine functionalization. The emission peaks in the photoluminescence (PL) spectra of the amine-functionalized diatom biosilica selectively enhanced the intensity by a factor of ten when compared to that of a bare diatom biosilica. The result showed a significant quenching of PL intensity of BSA at around 445 nm due to the interaction of amine-functionalized diatom-BSA protein complex. The detection limit was found to be 3 × 10(-5) M of BSA protein. Hence, the study proves that the functionalized frustule of Amphora sp. is an effective quantitative analytical tool for optical label-free biosensing applications.
authors.affiliation: Department of Nanoscience and Technology, Bharathiar University, Coimbatore, 641 046, Tamilnadu, India.
authors.forename: S
authors.initials: S
authors.lastname: Viji
authors.forename: M
authors.initials: M
authors.lastname: Anbazhagi
authors.forename: N
authors.initials: N
authors.lastname: Ponpandian
authors.forename: D
authors.initials: D
authors.lastname: Mangalaraj
authors.forename: S
authors.initials: S
authors.lastname: Jeyanthi
authors.forename: P
authors.initials: P
authors.lastname: Santhanam
authors.forename: A Shenbaga
authors.initials: AS
authors.lastname: Devi
authors.forename: C
authors.initials: C
authors.lastname: Viswanathan
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D002417:Cattle; D017377:Diatoms / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry; D016062:Porosity; D011437:Propylamines; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000302:isolation & purification*; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D011437:Propylamines; D012821:Silanes; C082343:silanol; D012710:Serum Albumin, Bovine; D012822:Silicon Dioxide; C477625:amino-propyl-triethoxysilane