Microwave-assisted synthesis and characterization of hydrophilically functionalized polygalacturonic acid

Microwave-assisted synthesis of a new class of polymeric surfactants based on polygalacturonic acid (PGA) is presented. PGA is water-insoluble and not surface-active under normal conditions. Single-step hydrophilic modification of PGA with taurine (2-aminoethane sulfonic acid) renders it surface-active. The modification can be carried out either using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDCl) as a coupling agent or using microwave irradiation without a catalyst. Microwave irradiation significantly shortens reaction times and eliminates the need for a coupling agent. In all cases, functionalization was confirmed using 1H NMR, FTIR spectroscopy and elemental analysis. PGA-SO3 exhibits surface-active properties comparable to commercial surfactants, Triton X-100 and sodium lauryl sulfate. Detailed cytotoxicity evaluation performed using human dermal fibroblast (HDF) and human leukemic (HL-60) cell lines indicate that PGA-SO3 is not toxic even at 20 fold higher concentrations. These polymeric surfactants synthesized from PGA with no demonstrable cytotoxicity have the potential for serving as ‘greener’ alternatives to common petrochemical-based surfactants.