Abstracts

Chemiluminescence (CL) is widely used for hydrogen peroxide detection, mainly exploiting the highly sensitive peroxidase-luminol-H₂O₂ system. Hydrogen peroxide plays an important role in several physiological and pathological processes and is produced by oxidases, thus providing a straightforward way to quantify these enzymes and their substrates [1]. Recently, biomolecular self-assembled materials obtained by guanosine and its derivatives and displaying peroxidase enzyme-like catalytic activity have received great interest for hydrogen peroxide biosensing [2]. These soft materials are highly biocompatible and can incorporate foreign substances while preserving a benign environment for biosensing events. In this work, a binary guanosine hydrogel prepared using a mixture of guanosine and guanosine 5′-monophosphate in the presence of K⁺ ions are loaded with a CL reagent (luminol) and a catalytic cofactor (hemin), to produce a functional material showing peroxidase-like activity to the CL reaction of luminol with H₂O₂. The hydrogel is then functionalized with a specific oxidase enzyme to enable marker biosensing: the hydrogen peroxide produced by analyte oxidation reacts, in the presence of the self-assembled guanosine/hemin gel mixture, with luminol to produce photon emission. The biosensor takes advantage of both the features of CL detection, offering high detectability and amenability to miniaturization, and of the 3D porous structure of hydrogel, as providing increased stability and catalytic activity even in alkaline and oxidizing conditions of incorporated enzymes. In this work, we show the development of four guanosine hydrogel – based biosensors for the detection of glucose, xanthine, uric acid and lactate by simple incorporation of corresponding oxidases: glucose oxidase (GOx) [3], xanthine oxidase (XOD), urate oxidase (UO) and lactate oxidase (LOx). Exploiting 3D printing technology, smartphone-based portable devices for CL biosensors were developed, verifying the applicability to quantify biomarkers of clinical interest at the point-of-care (POC). The photon emission from the CL reaction was detected using a portable device that employs a smartphone's CMOS (complementary metal oxide semiconductor) camera for CL emission detection. References[1] Patel, V. et al. 2020. Solid state sensors for hydrogen peroxide detection. Biosensors. 11, 9.[2] Bhattacharyya, T. et al. 2017 Supramolecular hydrogel inspired from DNA structures mimics peroxidase activity. ACS Biomater. Sci. Eng. 3, 2358–2365. [3] Calabria, D. et al. 2023 Smartphone-Based Chemiluminescence Glucose Biosensor Employing a Peroxidase-Mimicking, Guanosine-Based Self-Assembled Hydrogel. Biosensors, 13(6), 650.