RESUMEN
Engineering nanotraps to immobilize fragile enzymes provides new insights into designing stable and sustainable biocatalysts. However, the trade-off between activity and stability remains a long-standing challenge due to the inevitable diffusion barrier set up by nanocarriers. Herein, we report a synergetic interfacial activation strategy by virtue of hydrogen-bonded supramolecular encapsulation. The pore wall of the nanotrap, in which the enzyme is encapsulated, is modified with methyl struts in an atomically precise position. This well-designed supramolecular pore results in a synergism of hydrogen-bonded and hydrophobic interactions with the hosted enzyme, and it can modulate the catalytic center of the enzyme into a favorable configuration with high substrate accessibility and binding capability, which shows up to a 4.4-fold reaction rate and 4.9-fold conversion enhancements compared to free enzymes. This work sheds new light on the interfacial activation of enzymes using supramolecular engineering and also showcases the feasibility of interfacial assembly to access hierarchical biocatalysts featuring high activity and stability simultaneously.
Asunto(s)
Hidrógeno , Catálisis , Hidrógeno/químicaRESUMEN
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.
Asunto(s)
Técnicas Biosensibles , Estructuras Metalorgánicas , Alginatos , Glucosa , Glucosa Oxidasa/química , Hidrogeles , Estructuras Metalorgánicas/química , Peroxidasas , Teléfono InteligenteRESUMEN
Multienzyme biocatalytic cascade systems (MBCS) have attracted widespread research in the field of biosensing due to selective substrate transformations and signal amplification function. However, the poor stability of enzymes significantly restricts their effectiveness in practical applications. The spatial organization of MBCS within porous organic frameworks (POFs), such as metal-organic frameworks, covalent organic frameworks, and hydrogen-bonded organic frameworks, is regarded as a promising strategy to overcome these challenges. This advanced biotechnology sets up a POFs microenvironment for enzymes immobilization, and thus make it possible to shield the enzyme from the external stimulus by POFs-guided structural confinement. Simultaneously, the tailorable porous structure of POFs shell allows for the selective transport of substrates into interior enzymes, thereby accelerating the sensing process. Herein, we present the concept of this POFs-confined MBCS, wherein enzymes were completely encapsulated into, rather than adsorption onto, the POFs. We highlight the new strategies for MBCS spatial organization through rational POFs support, and describe how this new bio-nanosystem that integrates framework and enzymes functions can be designed as a versatile biosensing platform. In addition, the challenges and outlooks are also discussed.