**5. Magnetic nanoparticles**

The insurgence of antimicrobial resistance is the greatest promoter of the fabrication of cutting-edge drug delivery systems. Iron oxide nanoparticles have always merited an outstanding place in drug delivery, thanks to their recognized biomedical importance, precise targeting, and biocompatibility [50].

Bearing this in mind, groups of investigators have recently published promising studies endorsing the development of superparamagnetic, fluorescent, noncytotoxic nano systems with antifungal activity against some fungal strains, namely *H. capsulatum*. In a summarized manner, iron oxide nanoparticles (IONPs) were synthesized using macromolecular stabilizing starch, noteworthy for their biocompatibility and agglomeration prevention. Upon encapsulation with starch, a shift in magnetic behavior takes place, converting the once weakly ferromagnetic IONPs into superparamagnetic (SPIONs) [50, 51]. The SPIONs were successfully incorporated in a fluorescently modified carrier system, enabling not only an easy identification of the system in a living body but also the application of this system in photodynamic therapy. An alarming discovery of this research is that H*. capsulatum* was found to be highly susceptible to the designed nano system in PTD studies, whereas it was resistant to the antifungal griseofulvin [51].

Specific drug targeting to the choroid has lately aroused special interest, on behalf of the rising blindness figures in the aged population and the choroid's unique architecture as one of the most vascularized tissues in the human body.

Magnetic iron oxide nanoparticles stabilized with carboxylic acid, have been covalently functionalized with a recombinant VEGF (vascular endothelial growth factor) permitting the preferential release of the drug into the choroid layer [52]. Albeit the study's core focus was angiogenesis and so they evaluated a monoclonal antibody (bevacizumab), the information conveyed is transposable to histoplasmosis infection. As a matter of fact, and as previously stated, ocular histoplasmosis instigates neovascularization of choroidal vessels, as can be noticed in **Figure 6**.

All in all, magnetic iron oxide nanoparticles can be a powerful strategy for cellspecific eye targeting. Their potential against *Candida* sp. has already been proven and amphotericin B has also been encapsulated in this nano system with enhanced fungicidal activity and reduced side effects [53]. In addition, these systems are biodegradable, intrinsically safe, exhibit increased half-life and their release localization can be controlled [52].
