Synthesis and Characterization of Sodium-Alginate-Stabilized Copper Hydroxide as an Antibacterial Agent in Topical Gel Formulation

Chen, Sze Ni (2025) Synthesis and Characterization of Sodium-Alginate-Stabilized Copper Hydroxide as an Antibacterial Agent in Topical Gel Formulation. Final Year Project (Bachelor), Tunku Abdul Rahman of Management and Technology.

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Abstract

This thesis discusses the synthesis, characterization and application of a sodium-alginate-stabilized copper hydroxide (SACuH) as an antibacterial topical gel. The first step was to synthesize SACuH using the chemical co-precipitation method in which 1% sodium alginate was employed as a surfactant to control the co-precipitation of Cu(OH)2 from copper sulfate (CuSO4) and sodium hydroxide (NaOH). The SACuH powder was then incorporated into a base gel that contained aqua, glycerin, copolymer, triethanolamine and phenoxyethanol. The gel formulations were prepared in different concentrations, which was in the range of 1-20 mg/mL by adjusting the amount of SACuH powder, ultrapure water and the commercial base gel used. The SACuH powder was verified and characterized using a combination of powder X-ray diffraction (PXRD), field-emission scanning electron microscopy (FE-SEM), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), UV–Vis spectroscopy, zeta potential analysis, and thermogravimetric analysis (TGA). Additionally, the rheological properties of the gel formulations were confirmed to be shear thinning which was deemed suitable for topical applications where spreadability should be well-controlled. The synthesized SACuH gel formulations were tested for their antibacterial properties employing both the standard agar diffusion method and time-kill kinetic study. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were selected due to their known roles in worsening eczema. In agar diffusion, the inhibition of E. coli increased across the concentration range of 5 to 15 mg/mL gel formulations. Conversely, activity against S. aureus was present but weaker which was attributed to the cell-wall structural differences found in Gram-positive (S. aureus). Moreover, in the time-kill kinetic study, the 10 mg/mL gel formulation was performed best in killing E. coli among the other concentrations, as it was achieving a log reduction of more than 3.7 correspond can kill more than 99.9 % of bacteria within 1 hour which was better than the minimum threshold set by the Environmental Protection Agency (EPA) for a product to be marketed as an antibacterial product.