Artificial Bifunctional Photozyme of Glucose Oxidase–Peroxidase for Solar-Powered Glucose–Peroxide Detection in a Biofluid with Resorcinol–Formaldehyde Polymers

Abstract

Photozymes or artificial photosynthesis based on alternative natural enzymes is vital for the sustainable development of next-generation healthcare, energy, and materials science. Herein, we report resorcinol–formaldehyde (RF) resins as a solar-driven metal-free bifunctional glucose oxidase–peroxidase stand-alone photozyme for the colorimetric dual detection of hydrogen peroxide and glucose. The π-bond conjugated benzenoid–ortho/para quinoid RF polymers are efficient for glucose oxidation and hydrogen peroxide reduction with concurrent 3,3′,5,5′-tetramethylbenzidine oxidation under natural sunlight. The photoinduced colorimetric process could detect H2O2 up to 3.5 μM at 652 nm with the linear range of 0.1–2 mM. A limit of detection of 9.2 μM was exhibited by the system while measuring glucose with a linearity from 0.2 to 8.5 mM. The formation of hydroxyl radicals ( • OH) from glucose oxidation reactions was evidenced by spin trapping electron paramagnetic resonance studies conducted herein. The results indicated that RF resins possessed strong intrinsic glucose oxidase and peroxidase (POx)-like activity under natural sunlight with promising storage and operation. This simple photozyme will definitely have potential uses in biomimetic solar-driven catalysis, bioenergy, and biomedicine.

Electrochemical Column Cell for Continuous Oxidative Inactivation of Pathogens and Reductive Removal of Toxic Heavy Metals

“…CF (6 cm × 3 cm) was submerged in 250 mL of 0.1 M OB solution and sonicated for 1 h to produce oxalate intercalated CF. The synthesis of the resorcinol formaldehyde (RF) polymer has been detailed in our previous study . RF microgranules (average size ∼ 1 μm) were added to a fresh OB solution (1 mg mL –1 ), followed by the oxalate-treated CF being placed inside it and connected with a variable DC adapter (3–12 V supply with 1.5 V increments) at the negative connection.…”

“…The voltage between electrodes was optimally kept at 9 V for favorable GO synthesis on CF (PEGO-CF). The setup was kept under sunlight for photoactivated generation of ROS by RF for production of GO and intercalation of the in situ-generated GO with the CF surface. PEC functionalization is performed in an aqueous system of dispersed RF polymers under direct sunlight illumination without the use of a strong acid/base or an oxidant.…”

“…We report for the first time, photoelectrochemical (PEC) production of GO on CF surface in a buffer of oxalic acid (OB) at pH 7 under stirring. For PEC generation, we introduce resorcinol formaldehyde polymers as semiconductor material to enrich the generation of nascent hydroxyl and dioxygen radicals ( ● OH and ● O 2 – ) under light illumination for effective oxidation of the CF material during electro-oxidation . Generation of ROS from chemically modified polymers has already been demonstrated by our group. , Electrogenerated hydroxyl radicals ( ● OH) are short-lived, and the exfoliated graphene synthesized from graphite has a low carbon-to-oxygen ratio. , To produce a better C/O ratio in GO by electrochemical exfoliation of graphite (a constituent of CF), it is crucial to “prolong” the lifetime of the electrogenerated strong oxidants (e.g., ● OH) to ensure that they react with graphene effectively.…”

“…For this, a RF–oxalate buffer system was ideal for the sweep and long-lived production of ● OH concurrently via the PEC technique. The oxalate ion is used as the intercalant, , whereas RF assisted in producing long-lived ● OH radical under solar light . The method bypasses the harsh modified Hummer’s method, even bypassing the strong acid environment (HNO 3 or H 2 SO 4 ) generally required in electrochemical methods …”

Chromophoric Dendrimer-Based Materials: An Overview of Holistic-Integrated Molecular Systems for Fluorescence Resonance Energy Transfer (FRET) Phenomenon

“…Considering these backgrounds, the molecular design and the potentially adequate performance of photoactive environments emerge as promissory candidates that could play a key role in light-energy processing [20][21][22]. Specifically, molecular environments susceptible to photo-induced energy transfer could have a high potential of application to mimic nature's behavior, e.g., the photosynthesis process [23,24]. Thus, the rigorous observation of the highly complex systems that make up nature has inspired numerous researchers to seek alternatives for the design of mimicking artificial systems [25,26].…”