*3.2. Storage Stability Determination*

By preserving NPs in double-distilled water (DDW) at 4.0 ◦C for twenty days, the storage stability of the particles was established. The CSGA-1.0 size changed slightly from 403.7 ± 0.7 to 413.1 ± 0.8 nm (Table 1), which might be related to NP clumping since size differences in aggregated systems are common for various causes [28]. The zeta potential values obtained in this investigation ranged from +15.4 to +25.4 mV, indicating their stability.

The CSGA-1.0 formulation will be chosen for future research in vivo and in vitro because of its smaller size, higher loading capacity, and better storage stability.

#### *3.3. Ionic Group Interaction Study Using Fourier Transform Infrared Spectroscopy (FTIR)*

Firm peaks indicate asymmetrical NH2 stretching vibration in CSGA-conjugated NPs at 3455.94 cm−1, whereas O-H stretching vibration is indicated by peaks at 3297.16 cm−<sup>1</sup> (Figure 2a,b). In earlier research [29] with CSCRG NPs, it was found that a high peak at 3444.75 cm−<sup>1</sup> in raw chitosan polymer suggested an asymmetrical NH2 stretching vibration [30]. Peaks in gum acacia powder indicated O-H stretching vibration at 3455.94 cm<sup>−</sup>1, C-H stretching vibration at 2929.66 cm−1, and o-amino- or o-hydroxyaryl ketones at 1635.25 cm−<sup>1</sup> [31]. The peak at 1071.13 cm−1, on the other hand, indicated CH3 rocking vibration. Due to H-bonding between the COOH group of gum acacia and the NH2 of chitosan, the peak at 3400–3500 cm−<sup>1</sup> seems to be wide. The fungicide loading within the nanocomposite is shown as a peak at 1635.17 cm−<sup>1</sup> in mancozeb-loaded CSGA NPs. This is also supported by a previous study in which a researcher validated the encapsulation of acetamiprid in a nanoform by seeing a peak at 1633 cm−1, which corresponds to the stretching vibration of C=N/C-N [27].

#### *3.4. Transmission Electron Microscopy (TEM)*

TEM results (Figure 2c,d) confirmed the formation of discrete, small, round conjugated nanoparticles with fungicide seen inside the NPs as a dark gray spot for loaded NPs [32]. TEM micrographs verified crystalline nanocomposite formation and better understood the biopolymeric nanoparticle's shape and size. The TEM pictures in this study show that the formed NPs were well dispersed, designating a monodispersed nature of synthesized nanoparticles and following previous research [27].

**Figure 2.** Fourier transform infrared spectra and TEM micrographs of conjugated nanoparticles; FTIR spectra of (**a**) gum acacia, (**b**) mancozeb-loaded NPs, (**c**) TEM micrograph (at 200 kV, ×5000 magnification, 0.5 μm scale bar) of blank NPs, (**d**) TEM of mancozeb-loaded NPs (at 200 kV, X7000 magnification, 0.5 μm scale).
