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.

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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.