Synthesis, characteristics, and antibacterial effects of biomaterials in nanoscale

Abstract

In this thesis, lignin/tannin nanoparticles (LNP/TNP) from different sources and processes were synthesized by nanoprecipitation method using lignin/acetone (and tannin/acetone) as solvents, and distilled water was used as anti-solvent. The MIC assays followed the produced LNP/TNP dispersion to determine the antibacterial effect against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. Coli). The objective of this thesis was to study the size distribution, zeta potential, and morphology of LNP/TNP and to analyze their correlations with functional groups and molecular weight (Mw) of lignins/tannins by using the Principal Component Analysis (PCA) approach. The results of LNPs revealed that high phenolic hydroxyl (OH) amount and total OH quantity contributed to higher surface charges of LNPs. Furthermore, lignins that possessed low Mw would have more aliphatic OH content and resulted in larger LNPs. The size of LNPs and their surface charges were indirectly correlated. They had a relationship through low Mw of lignin that riched in aliphatic OH content. LNP dispersions that had the best antibacterial performance towards S. aureus also obstructed the growth of E. Coli