Isolation, characterization and evaluation of pineapple crown waste nanofiber gel entrapping ampicillin in topical bacterial infections

Cellulose nanofibers were isolated from pineapple crown waste by combined alkali and acid treatment method and then characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, and high-resolution transmission electron microscopy studies. Furthermore, pineapple nanofibers were incorporated in Carbopol 934P containing ampicillin as model drug to prepare topical gel for treating skin bacterial infections. The preferred gel formulation was evaluated for particle size (150 ± 0.6 nm), polydispersity index (0.303 ± 0.02), and drug content (99.87 ± 0.34%). The gel formulation was also evaluated by in vitro drug release, ex vivo drug permeation, and antibacterial and histopathological study. The in vitro drug release from gel formulation and the aqueous solution of drug was observed to be 34% and 99% (in 12 h), whereas the drug with the flux rate of 4.7879 ± 0.010 and 4.13963.98 μg/cm²/h permeated through skin from the gel formulation and the aqueous solution of drug, respectively, as determined by ex vivo diffusion study. The antibacterial activity against E. coli exhibited controlled release of the drug as determined by zone of inhibition for gel formulation (9.3 mm) when compared to the ampicillin drug (14.4 mm) solution. Histopathological analysis displayed no signs of toxicity when observed after application of gel formulation on goat ear skin. Furthermore, the cytotoxicity study of pineapple nanofibers based on MTT assay did not show any toxicity on healthy Vero cells in the concentration range of 10–80 μg/mL. Hence, it can be concluded that pineapple nanofiber possesses the potential for topical drug delivery applications with good permeation.