Papain functionalized Prussian blue nanozyme colloids of triple enzymatic function.

Prussian blue nanozymes were surface engineered with papain enzyme to develop processable nanoparticle dispersions with antioxidant and hydrolytic activities for biocatalytic applications. Enzyme coating improved the colloidal stability of the nanozymes and the obtained papain-Prussian blue hybrid showed remarkable peroxidase (vmax = 8.82 × 10-9 M s-1, KM = 12.3 mM), superoxide dismutase (IC50 = 14.6 ppm) and protease-like (41.2 U L-1) activities.

Coamplified Nanozyme Cocktails for Cascade Reaction-Driven Antioxidant Treatments.

Antioxidant nanozymes are powerful tools to combat oxidative stress, which can be further improved by applying nanozyme mixtures of multiple enzymatic function. Here, cocktails of Prussian blue (PB) nanocubes and copper(II) exchanged ZSM-5 zeolites (CuZ) with enhanced reactive oxygen species (ROS) scavenging activity were developed. Surface functionalization of the particles was performed using polymers to obtain stable colloids, i.e., resistant to aggregation, under a wide range of experimental conditions. The nanozyme cocktails possessed advanced antioxidant properties with multiple enzyme-like functions, catalyzing the decomposition of ROS in cascade reactions. The activity of the mixture far exceeded that of the individual particles, particularly in the peroxidase assay, where an improvement of more than an order of magnitude was observed, pointing to coamplification of the enzymatic activity. In addition, it was revealed that the copper(II) site in the CuZ plays an important role in the decomposition of both superoxide radicals and hydrogen peroxide, as it directly catalyzes the former reaction and acts as cocatalyst in the latter process by boosting the peroxidase activity of the PB nanozyme. The results give important insights into the design of synergistic particle mixtures for the broad-spectrum scavenging of ROS to develop efficient tools for antioxidant treatments in both medical therapies and industrial manufacturing processes.

Engineering inorganic nanozyme architectures for decomposition of reactive oxygen species.

Enzyme-mimicking nanomaterials (nanozymes) with antioxidant activity are at the forefront of research efforts towards biomedical and industrial applications. The selection of enzymatically active substances and their incorporation into novel inorganic nanozyme structures is critically important for this field of research. To this end, the fabrication of composites can be desirable as these can either exhibit multiple enzyme-like activities in a single material or show increased activity compared to the nanozyme components. Conversely, by modifying the structure of a nanomaterial, enzyme-like activities can be induced in formerly inert particles. We identify herein the three main routes of composite nanozyme synthesis, namely, surface functionalization of a particle with another compound, heteroaggregation of individual nanozymes, and modification of the bulk nanozyme structure to achieve optimal antioxidant activity. We discuss in particular the different inorganic support materials used in the synthesis of nanozyme architectures and the advantages brought forth by the use of composites.

Aptamer Clicked Poly(ferrocenylsilanes) at Au Nanoparticles as Platforms with Multiple Function[†].

Aptamers are widely used in biosensing due to their specific sensitivity toward many targets. Thus, gold nanoparticle (AuNP) aptasensors are subject to intense research due to the complementary properties of aptamers as sensing elements and AuNPs as transducers. We present herein a novel method for the functional coupling of thrombin-specific aptamers to AuNPs via an anionic, redox-active poly(ferrocenylsilane) (PFS) polyelectroyte. The polymer acts as a co-reductant and stabilizer for the AuNPs, provides grafting sites for the aptamer, and can be used as a redox sensing element, making the aptamer-PFS-AuNP composite (aptamer-AuNP) a promising model system for future multifunctional sensors. The aptamer-AuNPs exhibit excellent colloidal stability in high ionic strength environments owing to the combined electrosteric stabilizing effects of the aptamer and the PFS. The synthesis of each assembly element is described, and the colloidal stability and redox responsiveness are studied. As an example to illustrate applications, we present results for thrombin sensitivity and specificity using the specific aptamer.