Advanced Lab-on-Fiber Optrodes Assisted by Oriented Antibody Immobilization Strategy

Abstract

Lab-on-fiber (LoF) optrodes offer several advantages over conventional techniques for point-of-care platforms aimed at real-time and label-free detection of clinically relevant biomarkers. Moreover, the easy integration of LoF platforms in medical needles, catheters, and nano endoscopes offer unique potentials for in vivo biopsies and tumor microenvironment assessment. The main barrier to translating the vision close to reality is the need to further lower the final limit of detection of developed optrodes. For immune-biosensing purposes, the assay sensitivity significantly relies on the capability to correctly immobilize the capture antibody in terms of uniform coverage and correct orientation of the bioreceptor, especially when very low detection limits are requested as in the case of cancer diagnostics. Here, we investigated the possibility to improve the immobilization strategies through the use of hinge carbohydrates by involving homemade antibodies that demonstrated a significantly improved recognition of the antigen with ultra-low detection limits. In order to create an effective pipeline for the improvement of biofunctionalization protocols to be used in connection with LoF platforms, we first optimized the protocol using a microfluidic surface plasmon resonance (mSPR) device and then transferred the optimized strategy onto LoF platforms selected for the final validation. Here, we selected two different LoF platforms: a biolayer interferometry (BLI)-based device (commercially available) and a homemade advanced LoF biosensor based on optical fiber meta-tips (OFMTs). As a clinically relevant scenario, here we focused our attention on a promising serological biomarker, Cripto-1, for its ability to promote tumorigenesis in breast and liver cancer. Currently, Cripto-1 detection relies on laborious and time-consuming immunoassays. The reported results demonstrated that the proposed approach based on oriented antibody immobilization was able to significantly improve Cripto-1 detection with a 10-fold enhancement versus the random approach. More interestingly, by using the oriented antibody immobilization strategy, the OFMTs-based platform was able to reveal Cripto-1 at a concentration of 0.05 nM, exhibiting detection capabilities much higher (by a factor of 250) than those provided by the commercial LoF platform based on BLI and similar to the ones shown by the commercial and well-established bench-top mSPR Biacore 8K system. Therefore, our work opened new avenues into the development of high-sensitivity LoF biosensors for the detection of clinically relevant biomarkers in the sub-ng/mL range.

The role of optical fiber sensors in the new generation of healthcare devices: a review

“…166 Recently, Ucci et al designed a lab-on-fiber optrode assisted by an oriented antibody immobilization strategy. 167 Lab-on-fiber technologies integrate functional materials onto optical fiber substrates at the micro and nanoscale to provide a multifunctional all-in-fiber device for many applications, ranging from optical processing, safety, and environmental monitoring. 168 The authors investigated the immobilization strategies to improve them through the use of hinge carbohydrates by involving homemade antibodies.…”

High sensitivity lab-on-fiber biosensing platform assisted by oriented antibody immobilization strategy

“…The sensorgrams also show that at concentrations between 0.5 and 5 nM the oriented antibody captures between 10 and 15 times more analyte. with the ΔRU measured in table [13].…”

“…The results obtained using the OFMT functionalized with the oriented 1B4 revealed the huge potentiality of this novel LoF biosensing platform to detect Cripto-1 at very low concentrations, equalling those attained with the mSPR benchtop system (0.05 nM). As reported in [13], the experiments were also carried out with commercial biolayer interferometry (BLI)-based device exhibiting detection capabilities much lower (by a factor of 250) than those provided by the OFMT biosensor (data not shown).…”

“…Figure1. Sensorgrams related to the binding of Cripto-1 at different concentrations (0.05 -0.5 -2.5 -5 -12.5 nM) to oriented 1B4 (a) and to the same antibody randomly immobilized (b) with the ΔRU measured in table[13].…”