Formulation and Characterization of Silver Nanoparticles gel Loaded with Notonia grandiflora Extract

Abstract

The present study was aimed at the green synthesis, characterization, and evaluation of silver nanoparticles
loaded gel using the ethanolic leaf extract of Notonia grandiflora. The leaves were extracted using petroleum
ether and ethanol, and the ethanolic extract showed a higher percentage yield (8.50% w/w) compared to the
petroleum ether extract (1.23% w/w). Preliminary phytochemical screening revealed the presence of
glycosides, flavonoids, phenolic compounds, saponins, diterpenes, and carbohydrates. The total flavonoid
and phenolic contents of the ethanolic extract were found to be 0.91 mg/100 mg and 0.62 mg/100 mg of dried
extract, respectively. Silver nanoparticles were synthesized using different concentrations of silver nitrate and
extract ratios. Among the prepared formulations, F3 exhibited the highest percentage yield (79.12 ± 0.18%)
and entrapment efficiency (0.902 ± 0.019 mg/100 mg quercetin equivalent). The optimized formulation
showed an average particle size of 215.45 nm and a zeta potential of −37.45 mV, indicating good stability.
The nanoparticles were incorporated into Carbopol 940 gel and evaluated for physicochemical properties.
The prepared gels exhibited acceptable appearance, homogeneity, spreadability, viscosity, extrudability, and
skin-compatible pH. In vitro drug release studies demonstrated sustained release characteristics, with
formulation F2 showing controlled drug release following zero-order kinetics (R² = 0.9868). Antimicrobial
activity studies against Staphylococcus aureus and Pseudomonas aeruginosa revealed that the nanoparticle-
loaded gel exhibited significantly higher zones of inhibition compared to the crude extract. The findings
suggest that Notonia grandiflora-mediated silver nanoparticle gel possesses promising physicochemical and
antimicrobial properties and may serve as a potential topical antimicrobial formulation.