*2.1.1 Synthesis of Nanopowders*

*Materials at the Nanoscale*

control bacterial diseases in agriculture.

with humans in different physiological mechanisms [17].

Ag-doped Na2Ti3O7 nanocrystals in *Drosophila*.

method, as descriptions in Refs. [21, 22].

embedded glass systems aiming at several applications.

**2. Nanocrystals in powder or embedded in glass systems**

Depending on how these nanocrystals are, for example, powdered or embedded in glass systems, the applicability is diverse. Thus, in applications in agronomy, dental, or biology, these doped nanocrystals must be in powder to be dispersed or not in solutions. In applications such as spintronics, the doped nanocrystals must be embedded in

ZnO, ZnS, or MgO nanoparticles have previously been used to control plant diseases caused by *Liberibacter crescens* [6]. *Xanthomonas alfalfae subsp. citrumelonis* and *Pseudomonas syringae* [7], *Xanthomonas perforans* [8], *Xanthomonas campestris pv. Campestris* [9], *Pantoea ananatis* [10, 11]*, Xanthomonas axonopodis pv. Citri* [12], *Xanthomonas oryzae pv. Oryzae* [13], and *Xanthomonas citri subsp. Citri* [14]. ZnO nanocrystals (NCs) may be doped with various elements, such as noble metals or transition metals, to increase their bactericidal effect. Doping is a process that consists of adding new elements to the nanoparticle's structure and changing their chemical characteristics [2]. Therefore, in this chapter book, we will show the results of ZnO NCs doped with silver (Ag), gold (Au), and magnesium (Mg) ions to

The fruit fly *Drosophila melanogaster* is a well-established model organism in various areas of science, including nanotoxicology [15]. The fruit fly also has 77% of the conserved genes related to human diseases [16] and considerable similarities

Several mutant lines for a broad range of human diseases are available in this model, besides its low cost and easy maintenance in the laboratory, in addition to a short life cycle, when compared to other model organisms such as fishes and mammals. Taken together, these characteristics make *Drosophila* a valuable model for studies that evaluate long-term and developmental effects in nanotoxicology [15]. Here we present results regarding the biocompatibility analysis of the pure and

The doped nanocrystals can be embedded in glassy systems, allowing for various applicability in devices. Zn1-xAxTe (A = Cr; Cu) nanocrystals (NCs) have been one investigated diluted magnetic semiconductor (DMS) system, due mainly to their strengthening *sp*-*d* exchange interactions with increasing A-doping concentration [18]. Cr and Cu-doped NCs simultaneously exhibit semiconductor and magnetic properties that may allow more diverse technological applications than undoped semiconductors [19, 20]. In this context, we present a very effective method for the growth of Cr2+ and Cu2+ ions-doped ZnTe NCs in a glass system (65P2O5 · 14ZnO · 1Al2O3 · 10BaO · 10PbO (mol %), named PZABP) using the fusion nucleation

Bi2Te3 semiconductors at the nanoscale are highly performing materials for thermoelectric and promising applications as topological insulators [23]. These nanosemiconductors' physical and chemical properties can enhance and perform new features based on quantum behavior and the electronic structure's doping [24–26]. The synthesis of Bi2Te3 NCs in diamagnetic host glasses allows the samples' high chemical stability. During fusion, Cr ions can incorporate into these systems allowing possible applications in the manufacture of magneto-optical devices [25–27]. Therefore, the long-range magnetic properties generated by the domain of the Cr ion doping spins, in addition to the insulating topological states of the Bi2Te3 semiconductor NCs, have aroused great interest in the scientific community for the development of spintronic nanodevices [24, 27, 28]. Thus, we will show some results of Cr doped Bi2Te3 NCs. Therefore, in this chapter, we show doped nanocrystals' results in powdered or

**142**

The pure and doped ZnO NCs were synthesized by coprecipitation by reference [29]. Pure and doped sodium titanate (Na2Ti3O7) were synthesized by reference [30].
