Engineering the ZIF-8 Pore for Electrochemical Sensor Applications─A Mini Review

Abstract

Zinc imidazole framework-8, abbreviated as ZIF-8, is a member of the metal organic framework (MOF) family. The chemical architecture of ZIF-8 consists of zinc metal duly coordinated with an organic ligand/fragment, resulting in a cagelike three-dimensional network with unique porosity. Because of such a unique architecture and physicochemical property, ZIF-8 has recently been explored in various applications such as gas storage, catalysis, electrochemical sensing, drug delivery, etc. Electrochemical sensors are currently a hot topic in scientific advances, where small, portable, Internet of Things (IoT)-enabled devices powered by electrochemical output show a newer path toward chemo and biosensor applications. The unique electrochemical property of ZIF-8 is hence explored widely for possible electrochemical sensor applications. The application and synthesis of the bare ZIF-8 have been widely reported for more than a decade. However, new scientific advancements depict tailoring the bare ZIF-8 structure to achieve smart hybrid ZIF-8 materials that show more advanced properties compared to bare ZIF-8. The framework is formed by joining inorganic (metal-containing) units with organic linkers by reticular synthesis, which results in the formation of a cross-linked crystalline network with permanent porosity. This unique porosity of ZIF-8 has recently been utilized for the encapsulation of suitable guest species to enhance the native physicochemical activity of ZIF-8. These engineered ZIF-8 materials show excellent results, especially for electrochemical sensing application. This review is intended to describe the research, including the one done by our group, where the ZIF-8 pore size is used for encapsulating nanoparticles, enzymes, and organic compounds to avail suitable sensor applications.

Effects of Ligand Substituents on the Character of Zn-Coordination in Zeolitic Imidazolate Frameworks

“…Zeolitic imidazolate frameworks (ZIFs) are a popular family of metal–organic frameworks (MOFs) and ZIF-8, a polymorph of zinc­(II)­2-methylimidazolate, , is their most prominent member. Although transition-metal imidazolates have been known for decades, these materials have entered the spotlight after the discovery of their high porosity , and exceptional thermal and chemical stability. , Thanks to their straightforward synthesis , and characterization as well as their intriguing properties − even under pressure − and in response to external stimuli, ZIFs have become relevant for a number of technological areas ranging from gas storage to photocatalysis, and from biomedicine to optoelectronics. − …”

Stable and Reusable Fe3O4/ZIF‐8 Composite for Encapsulation of FDH Enzyme under Mild Conditions Applicable to CO2 Reduction

“…Some reports indicating that these differences are considered not significant can be found [32] . However, the presence of proteins during the crystallization of MOF can lead to the formation of defects in the crystal that give rise to greater interconnections between the cavities and even, the pore size can be increased to accommodate the host but at the expense of some kind of structural modification [33,34] . Therefore, the synthesis of ZIF‐8 in presence of FDH could induce structural distortions and defects in the crystal which translate into an increase in the surface area and pore volume of the MOF.…”

Unveiling the synthesis patterns of nanomaterials: a text mining and meta-analysis approach with ZIF-8 as a case study

“…35,36 Accordingly, ZIF-8 has garnered significant interest in the literature for applications including gas storage and separation, adsorptive refrigeration, 37 biomolecule encapsulation, 38 catalysis, 39 and sensing. 40 Further, ZIF-8 can be synthesized from a number of strategies – for example using protic or aprotic solvents, 41 a range of temperatures, 42 reagent concentrations, 43 modulators and crystal growth modifiers, 44 and acid/base conditions. 45 In sum, over 7500 papers have been published regarding ZIF-8 to date.…”