## 4 The Use of Nanotechnology for the Improvement of Endophytic Biocontrol Agents  
Nanotechnology, which involves study of molecules or compounds at nanoscale, is a novel field of study with development and applications in various fields such as energy, medicine and agriculture [31]. Nanotechnology has shown its potential as a novel tool for the treatment of diseases [32], thus improving human health. Consequently, it has been suggested that these same techniques could serve the same purpose and have a positive effect on plant health [33]. Recently, nanomaterials have been applied in combination with microorganisms to aid and create new properties for dealing with diseases. Nanomaterials can be synthesized through physical, chemical, and green routes. Green synthesis involves the use of biological materials such as plants, bacteria and fungi to synthesize nanomaterials [32]. An exponential increase in accounts of nanoparticles in phytopathology has been noted over the last few decades [34]. In a study by [PERSON] et al. (2022) [35], copper oxide nanoparticles (CuO-NP) were biosynthesized from marine endophytic actinomycetes because of its antibacterial and antifungal properties. The NPs used were able to inhibit biofilm production from _Escherichia coli_ and _Proteus mirabilis_[35]. One notable finding of this study was that the biogenic nanoparticles exhibited a broad spectrum of antibacterial activity against human pathogenic bacteria. _P. mirabilis_ and _E. coli_, which are bacteria that mostly affect humans, but this study shows the ability of biogenic NPs to possess antifungal and antibacterial traits which could possibly be applied in the agricultural industry for the improvement of biocontrol agents in an effort to enhance phytopathogen tolerance [36]. Another nanoparticle that has displayed antifungal activity against pathogenic microorganisms is silver (Ag). A study by [PERSON] et al. (2021) [33], showed that Ag NPs synthesized from actinobacterium, _Rothia endoplytica_, had antifungal activity against _Candida albicans_. The study further explained the antibacterial mechanisms of the nanoparticles, which were attributed to its ability to reduce cell viability, promote cellular leakage of sugar and proteins and increase lipid peroxidation in _C. albicans_ (Figure 3). With the premise of using nanoparticles synthesized from endophytic microorganisms against human pathogens, more studies need to explore the potential this technique can have on the health and growth of plants, specifically commodity crops. Hence, [PERSON] et al., 2021 [33] depicted the potential of the application of _Rothia endoplytica's_ Ag-NP as a biocontrol agent for inhibiting various phytopathogens growth within plants. It has also been reported that biogenic zinc nanoparticles were observed to be effective against some phytopathogenic fungi [37]. A study by [PERSON] et al., 2022 [38] showed that Zn nanoparticles worked through multiple mechanisms to increase the plant's antioxidant and defense system against fusarium species. These mechanisms included the increase in phenolic compound production which have been cited in literature to have good antioxidant capabilities as well as the activation of the host defense mechanisms which were attributed to an increase in soluble proteins [38]. Another study also explored the anti-fungal activity of biogenic zinc oxide nanoparticles synthesized from three endophytic streptomyces species; _Streptomyces capillaries_ Ca-1, _Streptomyces zoomycetes_ Oc-5, and _Streptomyces pseudogriseolus_ Acv-11 against four phytopathogens (_Alternaria. alternate, Fusarium oxysporum, Pythium ultimum_, and _Aspergillus niger_) [39]. The study highlighted the ability of the nanoparticles to inhibit the phytopathogens in a concentration dependent manner. It also reported that the antioxidant activity of the nanoparticles was equivalent to or higher than known antioxidant compounds such as ascorbic acid [39].