202
J. A. Elegbede and A. Lateef
of artificial or synthetic or non-natural enzymes which is still emerging (Table 2).
Nanozymes have attracted enormous research interests on account of their exceptional properties when related with natural and classic artificial enzymes (Wei and
Wang 2013; Chen et al. 2014). Generally, natural enzymes have need of stringent
physiological circumstances and conditions in carrying out catalytic functions. These
stringent conditions include their restricted stability in severe environmental circumstances, the expensive cost of production, isolation, in addition to purification. But
unlike natural enzymes, nanozymes present undaunted biocatalytic potentials even
under the extreme conditions of temperatures, pH and forbearance to the digestion
by proteases (Singh 2019). Additionally, nanozymes have other advantages, such as
robustness, ease and lower cost of mass production. Moreover, nanozymes are proficient in displaying some unique properties with regard to their responses toward
external stimuli, shape, size and composition-dependent catalytic activities, large
surface area, in addition to displaying multiple functionalities (Wu et al. 2019).
Till now, nanomaterials have been investigated to mimic a series of natural
enzymes, like oxidase, peroxidase, catalase, superoxide dismutase (SOD), nuclease,
esterase, phosphatase, ferroxidase and protease (He et al. 2011; Singh et al. 2011;
Li et al. 2014; Vernekar et al. 2014; Janoš et al. 2015; Wang et al. 2016). The
inbuilt catalytic abilities of nanozymes have guaranteed their exploitation as artificial enzymes to either reinstate or improve abnormal enzymatic activities in patients
(Bhushan and Gopinath 2015). These nanozymes are being expansively analyzed to
ascertain a wide range of use in disease diagnosis and therapy, biosensing, immunoassays, theranostics, cell/tissue growth and proliferation, protection from oxidative
stress and pollutants removal (Xie et al. 2012; Lin et al. 2014; Zhou et al. 2017).
According to Singh (2019), the nanozymes that have been revealed so far can be
broadly divided into two categories; antioxidants (superoxidase dismutase and catalase mimetic nanomaterials) and pro-oxidants (peroxidase and oxidase mimetic nanomaterials), considering their functions either as free radicals scavenger or free radicals
generator during the catalytic reaction, respectively (Fig. 2).
Moreover, some nanomaterials are referred to as multifunctional nanozymes
because they combine the enzyme-mimicking abilities with the added characteristics like electrical, optical and magnetic properties. Hence, the multifunctional
nanozymes designed would not just incorporate multiple processes such as catalysis and separation more competently and cost-effectively but also present highperformance opportunities in practical applications for instance ultrasensitive sensing
and in situ monitoring. Some of these nanomaterials that have been expansively examined for various relevancies in biosensor development, diagnosis and therapeutics,
and environmental remediation, include iron oxide nanozymes having magnetic properties and metal nanozymes displaying SPR (Wu et al. 2018). Magnetic iron oxide
nanomaterials which are also denoted as magnetic nanoparticles (MNPs) are exceptional on account of their interactions with both the magnetic fields and field gradients. These facilitate easy magnetic separation, enrichment, and recycling, tracking
and visualization of the local environment of cells labeled with MNPs via magnetic
resonance imaging (MRI) (Lee et al. 2015). MNPs are regarded as being catalytically
inert; therefore, they are being broadly applied as a support which binds enzymes
J. A. Elegbede and A. Lateef
of artificial or synthetic or non-natural enzymes which is still emerging (Table 2).
Nanozymes have attracted enormous research interests on account of their exceptional properties when related with natural and classic artificial enzymes (Wei and
Wang 2013; Chen et al. 2014). Generally, natural enzymes have need of stringent
physiological circumstances and conditions in carrying out catalytic functions. These
stringent conditions include their restricted stability in severe environmental circumstances, the expensive cost of production, isolation, in addition to purification. But
unlike natural enzymes, nanozymes present undaunted biocatalytic potentials even
under the extreme conditions of temperatures, pH and forbearance to the digestion
by proteases (Singh 2019). Additionally, nanozymes have other advantages, such as
robustness, ease and lower cost of mass production. Moreover, nanozymes are proficient in displaying some unique properties with regard to their responses toward
external stimuli, shape, size and composition-dependent catalytic activities, large
surface area, in addition to displaying multiple functionalities (Wu et al. 2019).
Till now, nanomaterials have been investigated to mimic a series of natural
enzymes, like oxidase, peroxidase, catalase, superoxide dismutase (SOD), nuclease,
esterase, phosphatase, ferroxidase and protease (He et al. 2011; Singh et al. 2011;
Li et al. 2014; Vernekar et al. 2014; Janoš et al. 2015; Wang et al. 2016). The
inbuilt catalytic abilities of nanozymes have guaranteed their exploitation as artificial enzymes to either reinstate or improve abnormal enzymatic activities in patients
(Bhushan and Gopinath 2015). These nanozymes are being expansively analyzed to
ascertain a wide range of use in disease diagnosis and therapy, biosensing, immunoassays, theranostics, cell/tissue growth and proliferation, protection from oxidative
stress and pollutants removal (Xie et al. 2012; Lin et al. 2014; Zhou et al. 2017).
According to Singh (2019), the nanozymes that have been revealed so far can be
broadly divided into two categories; antioxidants (superoxidase dismutase and catalase mimetic nanomaterials) and pro-oxidants (peroxidase and oxidase mimetic nanomaterials), considering their functions either as free radicals scavenger or free radicals
generator during the catalytic reaction, respectively (Fig. 2).
Moreover, some nanomaterials are referred to as multifunctional nanozymes
because they combine the enzyme-mimicking abilities with the added characteristics like electrical, optical and magnetic properties. Hence, the multifunctional
nanozymes designed would not just incorporate multiple processes such as catalysis and separation more competently and cost-effectively but also present highperformance opportunities in practical applications for instance ultrasensitive sensing
and in situ monitoring. Some of these nanomaterials that have been expansively examined for various relevancies in biosensor development, diagnosis and therapeutics,
and environmental remediation, include iron oxide nanozymes having magnetic properties and metal nanozymes displaying SPR (Wu et al. 2018). Magnetic iron oxide
nanomaterials which are also denoted as magnetic nanoparticles (MNPs) are exceptional on account of their interactions with both the magnetic fields and field gradients. These facilitate easy magnetic separation, enrichment, and recycling, tracking
and visualization of the local environment of cells labeled with MNPs via magnetic
resonance imaging (MRI) (Lee et al. 2015). MNPs are regarded as being catalytically
inert; therefore, they are being broadly applied as a support which binds enzymes