PEGylation as a tool to improve the stability of garlic sulfides as nano‑protectants from stored‑product beetles infestation

This study aimed to develop PEGylation based nanoparticles using garlic essential oil (GEO) and polyethylene glycol (PEG)
by melt-dispersion method. Physico-chemical characteristics of GEO loaded PEG nanoparticles (GPNs) was analysed by
Differential Scanning Calorimetry (DSC), Dynamic Light Scattering (DLS), and Gas Chromatography (GC) techniques.
Optimized GPN was subjected to stability and physico-chemical characteristics analysis up to six-month storage. Then,
insecticidal potentiality of GPN was investigated and microstructural impacts on the beetle surface was observed under
Scanning Electron Microscopy (SEM). Among the developed GPNs, DLS characteristics revealed GPN4 as optimal with
195.90 nm of particle size, 0.25 PDI, and 86.48% of encapsulation efficiency. Significantly, there was no physico-chemical
changes on GPN4 during six-month storage compared to control. In GC analysis, diallyl sulfide, diallyl disulfide, and dial-
lyl trisulfide were detected as major constituents of GEO and GPN4. The GPN4 showed potential contact toxicities against
Sitophilus oryzae, Rhyzopertha dominica, and Tribolium castaneum adults with 165.73, 169.95, and 192.82 ppm of LC 50
values at 72 h exposure. SEM observations exhibited adhesion of powder-form nanoparticles and abrasions on the cuticular
surface of beetles. In conclusion, the study results suggested that GPN4 was a stable and potential contact toxicant, which
could be useful as nano-protectant against stored-product beetles.