title: Dual-excitation upconverting nanoparticle and quantum dot aptasensor for multiplexed food pathogen detection.
abstract: In this report, a dual-excitation sensing method was developed using aptamer-functionalized quantum dots and upconverting nanoparticles, exhibiting Stokes and anti-Stokes type excitation profiles, respectively. Conjugation of the aptamer-functionalized luminescent nanoparticles with the magnetic beads, comprising short DNA sequences that were partially complementary to the aptamer sequences, enabled facile separation of the analyte-free conjugates for fluorescent measurement. UV-Visible spectroscopy, Circular Dichroism spectroscopy, Dynamic Light Scattering and Polyacrylamide Gel Electrophoresis techniques were used to characterize the aptamer probes developed. The target-specific luminescent conjugates were applied for multiplex detection of model food pathogens, Salmonella typhimurium, and Staphylococcus aureus, in which the fluorescent emission spectra were obtained under UV excitation at 325nm for quantum dots and NIR excitation at 980nm for upconverting nanoparticles, respectively. The dual-excitation strategy was aimed to minimize cross-talk between the luminescent signals for multiplexed detection, and yielded limit of detection values of 16 and 28cfumL(-1) for Staphylococcus aureus, and Salmonella typhimurium, respectively. By employing a greater number of quantum dots and upconverting nanoparticles with non-overlapping fluorescent emissions, the proposed methodology might be exploited further to detect several analytes, simultaneously.
authors.affiliation: Sabanci University, Faculty of Engineering and Natural Sciences, 34956 Istanbul, Turkey.
authors.forename: Hasan
authors.initials: H
authors.lastname: Kurt
authors.affiliation: Sabanci University, Nanotechnology Research and Application Centre, 34956 Istanbul, Turkey. Electronic address: meralyuce@sabanciuniv.edu.
authors.forename: Meral
authors.initials: M
authors.lastname: Yüce
authors.affiliation: Sabanci University, Faculty of Engineering and Natural Sciences, 34956 Istanbul, Turkey.
authors.forename: Babar
authors.initials: B
authors.lastname: Hussain
authors.affiliation: Sabanci University, Faculty of Engineering and Natural Sciences, 34956 Istanbul, Turkey; Sabanci University, Nanotechnology Research and Application Centre, 34956 Istanbul, Turkey.
authors.forename: Hikmet
authors.initials: H
authors.lastname: Budak
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D005516:Food Microbiology; D006801:Humans; D049408:Luminescent Agents / Q000737:chemistry; D008163:Luminescent Measurements / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D045663:Quantum Dots / Q000737:chemistry*; D012480:Salmonella Infections / Q000382:microbiology; D012486:Salmonella typhimurium / Q000302:isolation & purification*; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000302:isolation & purification*
chemical_list: D052157:Aptamers, Nucleotide; D049408:Luminescent Agents
keywords: Aptamers; Aptasensor; Biosensors; Food pathogens; Quantum Dots; Upconverting nanoparticles