Real Time Monitoring of a UV Light-Assisted Biofunctionalization Protocol Using a Nanophotonic Biosensor

Abstract

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.

Experimental study of an evanescent-field biosensor based on 1D photonic bandgap structures

“…Half-antiBSA-antibodies (haBSA) have been used as bioreceptors in this work, which reduces even more the distance between the sensor surface and the recognition sites, and provides a proper orientation of these recognition sites. This biofunctionalization process, as well as the protocol for obtaining the half-antibodies, was previously described in [9–10], where the light-assisted immobilization of the half-antibodies was monitored in real time and in-flow using the PBG sensing structures. However, the sensing performance obtained for those experiments was relatively low, mainly determined by the low irradiation efficiency obtained when illuminating the photonic chip with UV light through the fluidic elements used to perform the experiments.…”

“…The biofunctionalization of the photonic sensors using the light-assisted immobilization process developed by our group [9–10 13], started with a cleaning of the SOI photonic chip using piranha solution (H 2 SO 4 /H 2 O 2 = 1:3) for 20 min and a subsequent activation of its surface with O 2 plasma for 10 min. Then, the SOI chip was silanized by immersing it in 1% TEVS in Milli-Q water (pH adjusted to 8) for 1 h and finally curing it at 110 °C for an additional 1 h. The reduction process used to obtain the half-antibodies consisted on the incubation (90 min at 37 °C) of the BSA antibodies in acetate buffer (0.15 M sodium acetate, 0.01 M EDTA, 0.1 M sodium chloride, pH 4.5) at 4 mg/mL concentration in the presence of 25 mM tris(2-carboxyethyl)phosphine (TCEP).…”

“…For the characterization of the photonic sensors, the SOI chip was assembled with a polydimethylsiloxane (PDMS) microfluidic flow cell and then placed in an opto-fluidic experimental setup allowing for the simultaneous interrogation of all photonic sensing structures within the chip [10–11]. In order to characterize the photonic chip, it was excited via their access grating couplers using light from a continuous-sweep tunable laser (Keysight 81980A) and the output light corresponding to each photonic structure within the chip was measured using an infrared camera (Xenics Xeva-1.7-320).…”

“…Taking this requirement into account, the PBG structures have been biofunctionalized using a light-assisted biofunctionalization protocol allowing for the covalent immobilization of half-antibodies, so that the thickness of the biorecognition layer can be significantly reduced. This biofunctionalization process was already demonstrated in [9–10], where the light-assisted immobilization of the half-antibodies was monitored in real time and in-flow using PBG sensing structures; however, a low sensing response towards antigen detection was obtained when using that in-flow biofunctionalization implementation. Therefore, in this work we have used an off-flow spotting process for the immobilization of the half-antibodies, which yields a higher surface coverage and thus significantly higher sensing responses, as demonstrated in the reported bovine serum albumin (BSA) detection experiments.…”

The Effects of Luminescent CdSe Quantum Dot-Functionalized Antimicrobial Peptides Nanoparticles on Antibacterial Activity and Molecular Mechanism

“…Research on nano-modification based on AP has shown that they can be combined with nanoparticles (NPs) to form nanomaterials with novel properties, due to their advantages in molecular recognition and antibacterial activity. 15 , 17 , 18 Currently, quantum dots (QDs) not only have very important applications in solar cells and phototransistor components, but also in biological applications including biosensors, 19 , 20 bioimaging 21 and biomedical research. 22 Cadmium selenide (CdSe) QDs with a size of 1–20 nm are currently used for in vivo imaging and diagnostic treatment.…”