Synthesis of Quaternary Dendronized Cellulose Derivatives and Their Potential Biological Applications

Abstract

In this dissertation, novel dendronized cellulose derivatives with biodegradable backbones were created by using sodium carboxymethyl cellulose (CMC) as the starting material. CMC was first transformed into its corresponding tetrabutyl ammonium salt, which reacted with 2-chloro-N-methylpyridinium iodide (CMPI) to produce an activated ester of [2-(N-methyl pyridium) carboxymethyl cellulose] iodide (MPCMCI). The reaction of MPCMCPI and di-tert-butyl 4-[2-(ter-butoxycarbonyl)ethyl]-4-aminoheptanedicarboxylate (BA) produced a new derivative with BA dendron elaborated on cellulose backbone (CMCBA). The degree of substitution (DS) of CMCBA was adjusted by controlling the relative concentration of CMPI and by choosing CMC with different DS or different molecular weights. Thermogrametric analysis (TGA) was used to estimate the DS of CMCBA. CMCBA was first hydrolyzed into its acid and further transformed into its corresponding tetrabutyl ammonium salt, activated ester (MPCMCBAI) with CMPI, and was further elaborated with BA to form the 2nd generation dendronized cellulose derivative (CMCBABA). CMCBABA was transformed into its corresponding activated (MPCMCBABAI) using the same procedure used in forming MPCMCBAI. The reactions of MPCMCI, MPCMCBAI, or MPCMCBABAI with N,N-dimethyl-1,3-propanediamine (DMPDA) produced the water soluble N,N-dimethylaminopropylcarbamoylmethyl cellulose (CMCDMPDA), CMCBADMPDA, and CMCBABADMPDA respectively. Both CMCBADMPDA and CMCBABADMPDA showed lower intrinsic viscosities than CMCDMPDA due to their dendritic structure. The hydrophobicity of the microenviroments of CMCBADMPDA and CMCBABADMPDA was investigated by studying the fluorescence of pyrene in their aqueous solutions. CMCBADMPDA was used to react with 3-chloro-2-hydroxypropyl trimethyl chloride (Quat188) or alkyl bromides to synthesize the dendronized cellulose with hydrophilic quaternary nitrogen periphery groups (CMCBADMPDA-Quat188) and the dendronized cellulose derivatives with hydrophobic alkyl chains with different carbon chain lengths on quaternary nitrogen (CMCBADMPDA-R). CMCBADMPDA-R with a carbon chain length of ten (CMCBADMPDA-C10) with high DS of C10 was further modified with Quat188 or propylene oxide to produce its water soluble form CMCBADMPDA-C10-Quat188 or CMCBADMPDA-C10-PO. The antimicrobial activity of these N-decyl,N,N-dimethyl quaternary dendronized cellulose derivatives was found using their minimum inhibitory concentration (MIC) against E-coli and S-aureus to be 32 ìg/mL and 16 ìg/mL respectively. The structure-antimicrobial property relations of quaternary ammonium cellulose derivatives were discussed by evaluating their MIC values and their molecular structures.