Bioinspired Nanozymes with pH‐Independent and Metal Ions‐Controllable Activity: Field‐Programmable Logic Conversion of Sole Logic Gate System

Abstract

gate functions, alternative logic systems based on other logic elements and input molecules generally need to be constructed to generate other logic functions, making logic conversion quite tedious and expensive. [11][12][13] However, in nature, different environmental factors usually make organisms to be programmed into different forms. Therefore, it is interesting and significant to develop the simple logic conversion strategy for the next generation of unconventional processors by learning from nature.Recently, inorganic nanomaterials with enzyme-like characteristics have attracted growing attentions as enzyme mimics (i.e., nanozymes). [14][15][16][17] Decades of researches have shown that unique properties and activities of nanozymes can bring about the diversity of application, [18,19] such as electrochemical sensor, [20,21] fluorescence assay, [22,23] colorimetric assay, [24] surfaceenhanced raman scattering, [25] and therapeutic medicine. [26,27] Therefore, it is expected that the peculiar characters of nanozymes will bring about novel applications, such as logic conversion.In nature, transition metal ions are associated closely with living organisms, which can positively or negatively influence the activities of enzymes. [28,29] On the other hand, some enzymes can maintain high activity in wide pH range by stabilizing their surface charge, space structure, and electron transfer rate in order to adapt well to different environments. [30] Inspired by these above phenomena, taking advantage of the biotemplates, nanostructure, and Co 3 O 4 , we synthesized Co 3 O 4 nanoparticles (NPs) with unique catalase-like activity: the influence of pH on activity is negligible in wide range of pH; the influence of the same metal ions on activity is variable under the different pH; the influence of the different metal ions on activity is versatile at the same pH. Given the peculiar characters of as-synthesized Co 3 O 4 nanozymes, we present the pHprogrammable logic conversion based on sole logic system. The metal ion-triggered logic gates based on nanozymes are constructed and the transformation of logic functions can be facilely realized by change pH of the same logic systems. This contribution would not only broaden the species and application area of nanozymes, but also open novel avenues for logic conversion on the untraditional processors and the pH-switchable sensing of multiple metal ions.In nature, different environmental factors make organisms to be programmed into different forms. However, it is difficult and significant to realize the fieldprogrammable logic conversion of sole logic system for molecular logic gates. Here, the concept of pH-programmable "logic conversion" on the single logic gate based on the peculiar enzyme-mimicking activity is presented. Inspired by natural enzymes with high pH-stability and metal ions-stimulated activity, pH-independent and metal ions-controllable catalase mimics (Co3 O 4 nanozymes) are designed by protein-directed method. Although pH cannot directly change the activity of n...

Nanozymes for Environmental Pollutant Monitoring and Remediation

“…These nanocomposites can serve to enhance the catalytic activity or are dual-purpose nanozymes for the adsorption and detection of the metal ion of interest. Studies exploiting the oxidase [ 110 , 111 ] or catalase-like [ 112 , 113 ] activity of nanozymes for metal ion detection are limited. Whilst most peroxidase-like nanozymes exhibit high metal ion selectivity, the demonstrated examples of catalase-like nanozymes were cross-selective [ 112 , 113 ] with the ability to detect multiple metal ions under various conditions.…”

“…Han et al [ 112 ] have exploited the pH-sensitive catalase-like activity of Co 3 O 4 MNPs to discriminate metal ions. The nanoparticles were insensitive to pH in the range of 6 to 11 but highly influenced by the nature of the metal ion (Ca 2+ , Fe 3+ , Hg 2+ and Mn 2+ ).…”

Synthesis, Catalytic Properties and Application in Biosensorics of Nanozymes and Electronanocatalysts: A Review

“…The obtained MoO 3 NZs revealed excellent PO-like activity and were used, together with GOx, for colorimetric detection of glucose in human serum. In another work, Han and co-authors [44] used bovine serum albumin (BSA) as a biotemplate for Co 3 O 4 NZs synthesis. The obtained NZs had a spherical morphology with an average diameter of 60 nm and exhibited catalase-like activities.…”

Recent advances in the construction of nanozyme-based logic gates

“…Inspired from nature in which organisms can be programmed into different forms in different environment, Han et al realized the transformation of logic functions using definitive logic unit and inputs (Fig. 7) (Han et al 2018). The metal ions could alter the catalase-like activity of Co 3 O 4 nanoparticles in type-and pH-dependent manners.…”