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[EN] The authors describe a method for the detection of DNA by using immobilized molecular beacons (MBs) on the surface of silicon, with a view on possible application in biosensing. MB hybridization and protein recognition were interrogated on silicon-oninsulator (SOI) surfaces by using fluorescently tagged probes. In order to better understand the conformational changes that occur to MBs upon hybridization, the process was studied by using dual polarization interferometry (DPI). A model system was developed that matches thickness, mass, and density parameters. The results experimentally demonstrate that hybridization promotes the displacement of a protein away from the surface. This finding may be further exploited in techniques such as photonic sensors, thereby paving the way to the design of more sensitive biosensors based on the use of MBs. ; This research was funded by the European Union Horizon 2020 program (ICT-644242 SAPHELY project), the MINECO projects CTQ/2013/45875-R, and CTQ/2016/75749-R, FEDER, and GVA PROMETEO II 2014/40. ; Gonzalez-Lucas, D.; Bañuls Polo, M.; García-Rupérez, J.; Maquieira Catala, Á. (2017). Covalent attachment of biotinylated molecular beacons via thiol-ene coupling. A study on conformational changes upon hybridization and streptavidin binding. Microchimica Acta. 184(9):3231-3238. https://doi.org/10.1007/s00604-017-2310-4 ; S ; 3231 ; 3238 ; 184 ; 9 ; Huertas CS, Fariña D, Lechuga LM (2016) Direct and label-free quantification of micro-RNA-181a at Attomolar level in complex media using a Nanophotonic biosensor. ACS Sensors 1(6):748–756 ; Bañuls M-J, González-Pedro V, Barrios CA, Puchades R, Maquieira Á (2010) Selective chemical modification of silicon nitride/silicon oxide nanostructures to develop label-free biosensors. Biosens Bioelectron 25(6):1460–1466 ; Zhang G-J, Chua JH, Chee R-E, Agarwal A, Wong SM (2009) Label-free direct detection of MiRNAs with silicon nanowire biosensors. Biosens Bioelectron 24(8):2504–2508 ; Sassolas A, Leca-Bouvier BD, Blum LJ (2008) DNA biosensors ...

[EN] A label-free biosensor based on silicon-on-insulator (SOI) photonic bandgap (PBG) structures is performed for specific protein detection. First, the SOI sensing surface is functionalized using triethoxyvinylsilane (TEVS) organosilane. Then, a UV light photocatalyzed immobilization of polyclonal half anti-bovine serum albumin (haBSA) antibodies is performed. Finally, a direct detection of target BSA antigen is carried out. Both the immobilization and the detection steps are monitored by making a continuous tracking of the PBG edge shift. In order to confirm the recognition of the antigen by the immobilized antibody, a fluorophore-labelled secondary antibody was flowed at the end of the experiment in order to perform a confirmation fluorescence test after the photonic detection. ; This work was supported by Horizon 2020 Framework Program of the European Union under the project H2020-PHC-634013 (PHOCNOSIS). ; Sabek, J.; Torrijos-Morán, L.; Díaz-Betancor, Z.; Bañuls Polo, M.; Maquieira Catala, Á.; García-Rupérez, J. (2018). Live Tracking Biofunctionalization and Label-Free Protein Detection Performed by a Nanophotonic Biosensor. Proceedings. 4(1):1-6. https://doi.org/10.3390/ecsa-5-05718 ; S ; 1 ; 6 ; 4 ; 1

[EN] A proper antibody immobilization on a biosensor is a crucial step in order to obtain a high sensitivity to be able to detect low target analyte concentrations. In this paper, we present an experimental study of the immobilization process of antibodies as bioreceptors on a photonic ring resonator sensor. A protein A intermediate layer was created on the sensor surface in order to obtain an oriented immobilization of the antibodies, which enhances the interaction with the target antigens to be detected. The anti-bovine serum albumin (antiBSA)-bovine serum albumin (BSA) pair was used as a model for our study. An opto-fluidic setup was developed in order to flow the different reagents and, simultaneously, to monitor in real-time the spectral response of the photonic sensing structure. The antiBSA immobilization and the BSA detection, their repeatability, and specificity were studied in different conditions of the sensor surface. Finally, an experimental limit of detection for BSA recognition of only 1 ng/mL was obtained ; Funding from Spanish government through grants TEC2015-63838-C3-1-R (MINECO/FEDER, UE), TEC2013-49987-EXP BIOGATE, and CTQ/2016/75749-R, and from the European Commission through project H2020-644242-SAPHELY is acknowledged. Raffaele Caroselli also acknowledges the Generalitat Valenciana for funding his grant through the doctoral scholarship GRISOLIAP/2014/109. ; Caroselli, R.; Garcia Castello, J.; Escorihuela Fuentes, J.; Bañuls Polo, M.; Maquieira Catala, Á.; García-Rupérez, J. (2018). Experimental Study of the Oriented Immobilization of Antibodies on Photonic Sensing Structures by Using Protein A as an Intermediate Layer. Sensors. 18(4):1-15. https://doi.org/10.3390/s18041012 ; S ; 1 ; 15 ; 18 ; 4

1 6 4 ; S ; [EN] A label-free biosensor based on silicon-on-insulator (SOI) photonic bandgap (PBG) structures is performed for specific protein detection. First, the SOI sensing surface is functionalized using triethoxyvinylsilane (TEVS) organosilane. Then, a UV light photocatalyzed immobilization of polyclonal half anti-bovine serum albumin (haBSA) antibodies is performed. Finally, a direct detection of target BSA antigen is carried out. Both the immobilization and the detection steps are monitored by making a continuous tracking of the PBG edge shift. In order to confirm the recognition of the antigen by the immobilized antibody, a fluorophore-labelled secondary antibody was flowed at the end of the experiment in order to perform a confirmation fluorescence test after the photonic detection. This work was supported by Horizon 2020 Framework Program of the European Union under the project H2020-PHC-634013 (PHOCNOSIS). Sabek, J.; Torrijos-Morán, L.; Díaz-Betancor, Z.; Bañuls Polo, M.; Maquieira Catala, Á.; García-Rupérez, J. (2018). Live Tracking Biofunctionalization and Label-Free Protein Detection Performed by a Nanophotonic Biosensor. Proceedings. 4(1):1-6. https://doi.org/10.3390/ecsa-5-05718

[EN] A protocol for the covalent biofunctionalization of silicon-based biosensors using a UV light-induced thiol-ene coupling (TEC) reaction has been developed. This biofunctionalization approach has been used to immobilize half antibodies (hIgG), which have been obtained by means of a tris(2-carboxyethyl)phosphine (TCEP) reduction at the hinge region, to the surface of a vinyl-activated silicon-on-insulator (SOI) nanophotonic sensing chip. The response of the sensing structures within the nanophotonic chip was monitored in real time during the biofunctionalization process, which has allowed us to confirm that the bioconjugation of the thiol-terminated bioreceptors onto the vinyl-activated sensing surface is only initiated upon UV light photocatalysis. ; This work was supported by the Horizon 2020 Programme of the European Union under the project H2020-PHC-634013 (PHOCNOSIS). ; Sabek, J.; Torrijos-Morán, L.; Griol Barres, A.; Díaz-Betancor, Z.; Bañuls Polo, M.; Maquieira Catala, Á.; García-Rupérez, J. (2018). Real Time Monitoring of a UV Light-Assisted Biofunctionalization Protocol Using a Nanophotonic Biosensor. Biosensors. 9(1):1-9. https://doi.org/10.3390/bios9010006 ; S ; 1 ; 9 ; 9 ; 1 ; Chin, C. D., Linder, V., & Sia, S. K. (2007). Lab-on-a-chip devices for global health: Past studies and future opportunities. Lab Chip, 7(1), 41-57. doi:10.1039/b611455e ; Wu, J., Dong, M., Santos, S., Rigatto, C., Liu, Y., & Lin, F. (2017). Lab-on-a-Chip Platforms for Detection of Cardiovascular Disease and Cancer Biomarkers. Sensors, 17(12), 2934. doi:10.3390/s17122934 ; Estevez, M. C., Alvarez, M., & Lechuga, L. M. (2011). Integrated optical devices for lab-on-a-chip biosensing applications. Laser & Photonics Reviews, 6(4), 463-487. doi:10.1002/lpor.201100025 ; Vestergaard, M., Kerman, K., & Tamiya, E. (2007). An Overview of Label-free Electrochemical Protein Sensors. Sensors, 7(12), 3442-3458. doi:10.3390/s7123442 ; Johnson, B. N., & Mutharasan, R. (2012). Biosensing using dynamic-mode cantilever ...