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Immobilizing enzymes into microcarriers is a strategy to improve their long-term stability and reusability, hindered by (UV) light irradiation. However, in such approaches, enzyme-substrate interaction is mediated by diffusion, often at slow kinetics. In contrast, enzyme-linked self-propelled motors can accelerate this interaction, frequently mediated by the convection mechanism. This work reports on a new photosensitive polymeric Janus micromotor (JM) for UV-light protection of enzymatic activity and efficient degradation of substrates accelerated by the JMs. The JMs were assembled with UV-photosensitive modified chitosan, co-encapsulating fluorescent-labeled proteins and enzymes as models and magnetite and platinum nanoparticles for magnetic and catalytic motion. The JMs absorbed UV light, protecting the enzymatic activity and accelerating the enzyme-substrate degradation by magnetic/catalytic motion. Immobilizing proteins in photosensitive JMs is a promising strategy to improve the enzyme's stability and hasten the kinetics of substrate degradation, thereby enhancing the enzymatic process's efficiency.

Versatile sensing matrixes are essential for the development of enzyme-immobilized optical biosensors. A novel three-dimensional titanium dioxide nanotubes/alginate hydrogel scaffold is proposed for the detection of sweat biomarkers, lactate, and glucose in artificial sweat. Hydrothermally synthesized titanium dioxide nanotubes were introduced to the alginate polymeric matrix, followed by cross-linking nanocomposite with dicationic calcium ions to fabricate the scaffold platform. Rapid colorimetric detection (blue color optical signal) was carried out for both lactate and glucose biomarkers in artificial sweat at 4 and 6 min, respectively. The superhydrophilicity and the capillarity of the synthesized titanium dioxide nanotubes, when incorporated into the alginate matrix, facilitate the rapid transfer of the artificial sweat components throughout the sensor scaffold, decreasing the detection times. Moreover, the scaffold was integrated on a cellulose paper to demonstrate the adaptability of the material to other matrixes, obtaining fast and homogeneous colorimetric detection of lactate and glucose in the paper substrate when image analysis was performed. The properties of this new composite provide new avenues in the development of paper-based sensor devices. The biocompatibility, the efficient immobilization of biological enzymes/colorimetric assays, and the quick optical signal readout behavior of the titanium dioxide nanotubes/alginate hydrogel scaffolds provide a prospective opportunity for integration into wearable devices.

Magnetic field-induced synthesis and biocatalysis of magnetic materials have inspired great interest due to the flexible controllability of morphologies and unique magnetoelectrical properties. However, the interaction of the magnetic field and the reaction kinetics during the synthesis of magnetic nanochains has not been revealed. The collective motions in fluids and the multifunctional enhancements for bioreaction of 3D magnetic-controlled nanochains have not been systematically researched. Here, an integrated 3D magnetic control method was reported for the synthesis, collective motion, and multifunctional bioreaction enhancement of peasecod-like nanochains. The interactions of magnetic field and reaction kinetics were rationally controlled to synthesize magnetic nanochains of different morphologies. Collective motions of nanochains under alternating magnetic fields were studied to provide insights into the disturbance on confined fluids. Three mechanisms of reaction enhancement of nanostir, magnetic agent, and nanocatalyst were achieved simultaneously via 3D magnetic-controlled nanochains using a glucose oxidase-horseradish peroxidase multi-enzyme system. The peasecod-like nanochain also exhibited excellent reaction enhancement in cell-free protein synthesis reaction, which is desired for effective high-throughput screening. The integrated 3D magnetic control method through the whole process from fabrication to applications of magnetic nanomaterials could be extended to multifunctional biocatalysis and multi-task biomedicine.

Enzyme immobilization plays an essential role in solving the problems of the inherently fragile nature of enzymes. Although prominent stability and reuse of enzymes can be achieved by enzyme immobilization, their bioactivity and catalytic efficiency will be adversely affected. Herein, PdCu hydrogel nanozymes with a hierarchically porous structure were used to immobilize horseradish peroxidase (HRP) to obtain PdCu@HRP. In addition to the improvement of stability and reusability, PdCu@HRP displayed synergistically enhanced activities than native HRP and PdCu hydrogels. Not only the specific interactions between PdCu hydrogel nanozymes and enzymes but also the enrichment of substrates around enzymes by electrostatic adsorption of hydrogels was proposed to expound the enhanced catalytic activity. Accordingly, by taking advantage of the excellent catalytic performance of the PdCu@HRP and the glucose oxidase encapsulated in zeolitic imidazolate framework-8, colorimetric biosensing of the carcinoembryonic antigen via catalytic cascade reactions for achieving signal amplification was performed. The obtained biosensor enhanced the detection sensitivity by approximately 6.1-fold as compared to the conventional HRP-based enzyme-linked immunosorbent assay, demonstrating the promising potential in clinical diagnosis.

Polymersome nanoreactors encapsulating the enzymes or particulate catalysts attract interest because of their potential use as modular reactors to synthesize complex compounds via a cascade of chemical reactions in a single batch. To achieve these goals, a key requirement is the tunable permeability of the polymersome membrane, which allows the size-selective transportation of reagents and products while protecting the encapsulated catalysts during the chemical reaction. We report here a stimuli-responsive route for controlling the permeability of the polymersomes of the binary blend of poly(ethylene glycol)- b -polystyrene (PEG- b -PS) and poly(ethylene glycol)- b -poly(acrylbenzylborate) (PEG- b -PABB). The presence of H 2 O 2 (1 mM) in the medium (0.1 M PBS, pH 7.4) triggers the oxidation of benzyl borate pendants of PABB to form poly(acrylic acid) (PAA). This transformation results in the perforation of the compartmentalizing membrane of polymersomes by the dissolution of PEG- b -PAA domains embedded in the inert PEG- b -PS matrix. By controlling the composition of the stimuli-responsive block copolymer, the polymersomes of the binary blend exhibit size-selective permeability without losing the structural integrity. Release of fluorescent guests with different sizes (fluorescein, PEG2k- Cm , PEG5k-Rho) can be controlled by tuning the composition (PEG- b -PS/PEG- b -PABB = 100/0-80/20) of blended polymersomes. Selective permeability of the membrane provides protection of the encapsulated enzymes from external proteases present in the medium, resulting in the one-pot synthesis of small molecules via cascades of chemical reactions. The nanoparticular catalysts are also encapsulated within the permeable polymersomes, serving as modular reactors for the conversion of organic compounds via a cascade of reactions.