Enzymes-Encapsulated Defective Metal–Organic Framework Hydrogel Coupling with a Smartphone for a Portable Glucose Biosensor

Abstract

Enzymes featuring high catalytic efficiency and selectivity have been widely used as the sensing element in analytical chemistry. However, the structural fragility and poor machinability of an enzyme significantly limit its practicability in biosensors. Herein, we develop a robust and sensitive hybrid biosensor by means of co-encapsulating enzymes into a defective metal−organic framework (MOF), followed by a double-crosslinked alginate gelatinization. The defective MOF encapsulation can enhance the stability of enzymes, yet well preserve their biocatalytic function, while the alginate gelatinization allows the MOF biohybrid high stretchability and mechanical strength, which facilitates the integration of a bead-, fiber-, and sheet-like portable biosensor. In this work, the enzymes consisting of glucose oxidase and peroxidase are co-encapsulated into this MOF hydrogel, and it can efficiently convert glucose into a blue-violet product through the biocatalytic cascade of encapsulated enzymes, enabling the colorimetric biosensing of glucose on a miniaturized MOF hydrogel when coupling with a smartphone. Interestingly, this MOF biohybrid hydrogel outputs a stronger sensing signal than the free biohybrid powders, attributed to the catalytic product-accumulated effect of the highly hydrophilic microenvironment of the hydrogel. As a result, this portable biosensor can sensitively and selectively sense glucose with a linear range from 0.05 to 4 mM. Importantly, both the hydrophilic hydrogel and MOF "armor" endow enzymes with high durability, and its sensing activity was well-maintained even after placing the biosensor at room temperature for 30 d. We believe that this MOF biohybrid hydrogel has huge potential for the engineering of next-generation portable biosensors.

Pore Size Tunable Trypsin@ZIF-90 and Hydrogel Integrated Lateral Flow Point-of-Care Platform for ATP Detection

“…Ce-MOF has been reported to be induced by ALP to produce a macroporous structure, which can promote both the accessibility of interior active sites and the mass transfer to realize sensitive detection of phosphorylated biomarkers . In addition, a portable colorimetric biosensor was developed by integrating morphology-adjustable defective enzyme@MOF with a hydrogel and smartphone for glucose detection . Inspired by the ZIF-enabled efficient enzyme mineralization, we proposed an enzyme@ZIF synthesis strategy to regulate the porosity characteristic of the ZIF frame and catalytic activity of the mineralized enzyme as well as to construct a point-of-care test (POCT) platform for biomolecules.…”

“…27 In addition, a portable colorimetric biosensor was developed by integrating morphology-adjustable defective enzyme@MOF with a hydrogel and smartphone for glucose detection. 28 Inspired by the ZIF-enabled efficient enzyme mineralization, we proposed an enzyme@ZIF synthesis strategy to regulate the porosity characteristic of the ZIF frame and catalytic activity of the mineralized enzyme as well as to construct a point-of-care test (POCT) platform for biomolecules.…”

Optical biosensing systems for a biological living body

“…The second category relies on chromogenic reactions catalyzed by internal enzymes 19–23 . This kind of colorimetric biosensing system requires only the intrinsic catalytic reaction of enzymes and corresponding substrates, simplifying and reducing the cost of the chromogenic process.…”

MOF-On-MOF Dual Enzyme-Mimic Nanozyme with Enhanced Cascade Catalysis for Colorimetric/Chemiluminescent Dual-Mode Aptasensing

“…3−6 This is because multienzyme cascade catalysis not only converts a single substrate into more signal molecules to achieve signal amplification and improve detection sensitivity but also effectively improves the utilization of intermediates by reducing the diffusion of intermediates between enzymes, thus further improving the catalytic efficiency. 7 Despite the widespread use of enzymes, their preparation and purification are tedious, and the natural enzymes are expensive, easily inactivated, and poorly recovered and reused, which greatly limit their practical applications. To solve these problems, nanozymes with enzyme-like catalytic properties are ideal alternatives to natural enzymes because of their unique advantages such as low cost, high stability, recyclability and reusability, and adjustable catalytic activity.…”

“…Many catalytic processes in living organisms often require the synergistic action of multiple enzymes, and biocascade catalysis can efficiently and selectively mediate various biological processes in vivo. , By simulating nature, the study of multi-enzyme cascade systems has attracted increasing attention in recent years and are widely used in the fields of catalysis, biosynthesis, therapy, and sensing. − This is because multi-enzyme cascade catalysis not only converts a single substrate into more signal molecules to achieve signal amplification and improve detection sensitivity but also effectively improves the utilization of intermediates by reducing the diffusion of intermediates between enzymes, thus further improving the catalytic efficiency . Despite the widespread use of enzymes, their preparation and purification are tedious, and the natural enzymes are expensive, easily inactivated, and poorly recovered and reused, which greatly limit their practical applications.…”