Synthesis of oligoguanidine - Based on polycondensation and compare their Antimicrobial Activities with Chloramine B
Abstract
Oligoguanidine with chain extension were synthesized by condensation and cross-linking polymerizations in an attempt to increase molecular weight and charge density of the anti microbial oligoguanidine. The reactions are procedure at 170 oC for 5h with ratio molar of HMDA: GHC = 1: 1.1, refined by vacuum filter at 60 oC. The Oligoguanidine OHMG.HCl synthesized has molecular weight equal 521 g/mol, chain structure and good water solubility. The comparison results of the antimicrobial activities of oligoguanidine with chloramine B indicated that MIC index of OHMG.HCl is 5ppm during MIC index of chloramine B is 50 ppm; MBC of OHMG.HCl is 12 minutes and MBC of chloramine B is 11 minutes; The SEM, TEM imagines exhibited clear biocide, low residue microorganism of OHMG.HCl. The LC-MS spectrum indicates the presence of haloacetic acid following the bactericidal action of chloramphen B, while OHGM.HCl is not available. This result confirms the environmental friendliness of oligoguanidine.
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Introduction
Antimicrobial polymer is a range of agents with bacteria or fungi inhibition ability, which has been used widely in plastic, textile, water purification, and so on. Most of antimicrobial polymers bear cationic groups along polymer chains, thus facilitating the adsorption of the polymer onto bacteria surfaces and further inhibiting the growth of bacteria via various mechanisms. As one of the cationic antimicrobial polymers, the guanidine-based polymer has attracted substantial interests due to its wide spectrum antimicrobial activity, excellent biocide efficiency and nontoxicity. Oligoguanidine is usually synthesized by polycondensation between guanidinium and diamine, The chain cross-linking would occur if prolonging reaction time and increasing reaction temperature. At low molecular weight constrains the guanidine polymer as antimicrobial agent would be used [6],[12] Guanidine polymer inhibits bacterial growth by attacking them through electrostatic attraction between cationic guanidio-groups and anionic groups on the cell surface of bacteria. After attaching to bacteria cells, guanidine polymer induces bacterial membrane collapsed and intracellular components leaked. Therefore positive charge density, molecular weight and molecular structure of guanidine polymer would influence adsorption on bacterial surface and inhibition efficiency [4], [7], [10]. At present, antibacterial substances such as atomic chlorine, chloramine B are used in practice. However these antibacterial substances are often used in large quantities, especially when reducing, especially after in water disinfected, there are a residue and by-product of chlorine compounds that are directly harmful to the health of humans and organisms [1]. In this article, a method synthesizing oligohexamethyleneguanidine hydrochloride (OHMG.HCl) synthesis, and evaluating its disinfection efficacy over chloramine B are presented in detail.
Conclusion
Oligoguanidine OHMG.HCl was synthesized by a two-step polymerization consisting of condensation and cross-linking to obtain the antimicrobial oligomer with a higher molecular weightand cationic form with the higer positive charge density than pre-polymer. The Oligoguanidine synthesized has a chain structure, good water solubility and suitable for use as a disinfectant in wastewater treatment. Antimicrobial ability of OHMG.HCl was adjusted by varying alkyl monomer ratios at the same content of guanidio groups when they are absorbed into the cell walls of the bacteria
Results of the bactericidal efficiency comparison with Chloramine B showed that the synthetic OHMG.HCl has a fast killing time, low consumption environmental friendliness and not cause a toxic effect on health.