Nanogel drug delivery system loaded with Azadirachta indica A. Juss. (Neem) for potential treatment of wound infection: development and characterization

Abstract Background Herein, we report the development of a novel nanogels (NG) system loaded with Azadirachta indica (A. indica) Adrien-Henri de Jussieu (A. Juss.), commonly known as neem, for possible topical treatment of wound infections. Methods To develop A. indica extract-loaded NG, first, extract-loaded nanoparticles (NPs) were produced using poly-ε-caprolactone (PCL) as the nanocarrier polymer. Secondly, the NPs were entwined in chitosan (CS) hydrogel loaded with the extract of A. indica to prepare the loaded NG system. Blank NG was produced without the extract. The developed NG was characterized, and its antibacterial effect was evaluated. Results Phytochemical screening of ethanolic extract of A. indica leaves indicated the presence of saponins, flavonoids, glycosides, tannins, alkaloids, steroids, terpenoids, and anthraquinones. The characterization data revealed that the developed NG formulations are nanosized in the ranges of 140–440 nm and 190–610 nm for blank NG and A. indica extract-loaded NG, respectively, and have mostly spherical structures. The developed NG formulation displayed pH-dependent swelling and erosion that are in direct proportion to the change in pH. Fourier transform infrared spectroscopy (FTIR) showed various characteristic bands of A. indica and formulation excipients, confirming the encapsulation of the extract. The minimum inhibitory concentration (MIC) of the loaded NG was found to be 0.250 ± 0.05 mg/ml, 0.625 ± 0.15 mg/mL, and 0.250 ± 0.07 mg/mL for Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Salmonella typhi (S. typhi) strains of bacteria, respectively. The NG formulation exhibited significant bacterial inhibition zones which were recorded as 8 ± 2.0 mm (p < 0.05), 16 ± 3.0 mm (p < 0.05), and 6 ± 1.0 mm (p < 0.05) for S. typhi, E. coli, and S. aureus, respectively, as compared with that produced by the crude extract. Conclusions An A. indica extract-loaded NG was successfully developed, and it demonstrated good formulation features, stability under refrigerated and room temperature conditions, as well as useful antibacterial activity that could be used for potential wound infection treatment. Graphical abstract