Nanocomposite gels are novel materials mainly used in the medical field for the control drug release and distribution. In this study, the effect of the concentration of galactomannan/zinc oxide nanocomposite in a polymeric Carbopol matrix to obtain a functional nanocomposite gel was studied. The swelling, thermogravimetric, rheological, and antibacterial properties against Escherichia coli and Staphylococcus aureus were evaluated. The results indicate that there is a direct effect between the amount of the employed nanocomposite and the properties studied in the gels. In this regard, we present a formulation that demonstrates that the prepared nanocomposite gel has ideal properties to be used in the medical field as an antibacterial agent.

In this work, the preparation of an antibacterial galactomannan/Zn(OH) 2-ZnO composite material by a green process is proposed and demonstrated. The galactomannan polysaccharide was extracted from the arid-native mesquite (Prosopis spp.) seeds through a hydrothermal technique, and it was used as an organic polymeric matrix for the in situ chemical precipitation of the Zn(OH) 2-ZnO inorganic particles from simple reactions between Zn 2+ and NaOH. The preparation was performed under standard conditions in aqueous solutions. The composite material, which was obtained by centrifugation of the previous preparation, was characterized by X-ray diffraction, transmission and scanning electron microscopy, infrared spectroscopy and thermal analysis. By means of these techniques, it was deduced that the composite material is highly crystalline (about 94%), composed of about 92% inorganic and 8% organic portion, and has a predominant size of 760 nm and a mean size of 800 nm. The antibacterial activity of the composite material was also studied, which resulted better against Escherichia coli (Gram-negative bacterium) than against Staphylococcus aureus (Gram-positive bacterium), which was calculated in a difference of about 30%. This work presents the high potential of galactomannans to form functional composite materials with inorganic particles.