title: Improving the luminescence properties of aequorin by conjugating to CdSe/ZnS quantum dot nanoparticles: Red shift and slowing decay rate.
abstract: Changing the properties of photoprotein aequorin such as the wavelength emission and decay half-life by using bioluminescence resonance energy transfer (BRET) phenomenon is the main aim in this paper. BRET system was set up with CdSe/ZnS quantum dot nanoparticles as an acceptor molecule and photoprotein as an energy donor molecule. Quantum dots are semiconductor nanoparticles with very interesting optical properties, including broad excitation spectra, narrow and the symmetric band width emission spectra, tunable by their sizes, compositions, negligible photo-bleaching and good chemical and photo-stability. In this QD-BRET system, aequorin is conjugated to the carboxyl groups on quantum dot surface by EDC/NHS chemistry as cross linker. Bioluminescence energy generates by aequorin upon adding Ca(2+) and transfers to the quantum dots in a radiationless manner and emits at a longer wavelength. The determined bioluminescent parameters for this method included aequorin activity, emission spectra and decay half-life time. In fact, this spectrum tuning strategy resulted in a change in bioluminescent properties of photoprotein, therefore, the maximum emission wavelength shifted from 455 to 540nm and the decay time increased from 3.76 to 12.11s. Nowadays, photoproteins with different characteristics are capable of being employed as a reporter in multi-analyte detections and in vivo imaging.
authors.affiliation: Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: Nezam
authors.initials: N
authors.lastname: Jalilian
authors.affiliation: Analytical Chemistry Research Laboratory, Mobin Shimi Azma Company, Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Shanehsaz
authors.affiliation: Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran. Electronic address: sajedi_r@modares.ac.ir.
authors.forename: Reza H
authors.initials: RH
authors.lastname: Sajedi
authors.affiliation: Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: Morteza
authors.initials: M
authors.lastname: Gharaat
authors.affiliation: Nanobiotechnology Research Centre, Avicenna Research Institute, ACECR, Tehran, Iran.
authors.forename: Ramin
authors.initials: R
authors.lastname: Ghahremanzadeh
mesh_terms: D000331:Aequorin / Q000737:chemistry*; D019187:Cadmium Compounds / Q000737:chemistry*; D004735:Energy Transfer; D049449:Luminescence; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D012666:Semiconductors; D013440:Sulfides / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; D000331:Aequorin; C058667:cadmium selenide; C031238:zinc sulfide
keywords: Aequorin; BRET; Decay rate; Quantum dot; Red shift