Quaternary ammonium chitin nanoparticles for antibacterial nanomedicine

Abstract

This research was purposed to synthesize quaternary ammonium chitin as an antibacterial agent for biomedical applications such as wound dressing, nanomedicine or drug carrier. (Carboxymethyl)trimethyl ammonium chloride (CMA) was selected to modified onto chitin (CT) via acylation resulted in carboxymethyl trimethyl ammonium chitin (CTCMA). CTCMA possessed positive charges to interact with negatively charged bacterial cell membrane, leading to cell death. In order to study the effect of material size and shape to antibacterial activity with an expectation that an increasing in surface area should enlarge positively charged exposure in a consequence of enhancing antibacterial activity, thus, CTCMA nanoparticles and hydrogels were fabricated in this research via ultra-sonication technique and self-assembly. From FTIR spectra, CTCMA exhibited the characteristic peak of ester linkage at 1735 cm-1 shifted from carboxylic ester of CMA at 1726 cm-1 and from 13C-NMR spectra, CTCMA exhibited the chemical shift of CH2- at 66.85 ppm and +NCH3 at 63.85 ppm, indicating the successful acylation. The degree of acylation or degree of substitution was determined as 1.67. Dynamic light scattering technique showed that particle size and surface charged of CTCMA were about 284.8±65.42 nm and 0.61±0.06, respectively. CTCMA was prepared into colloidal nanoparticles dispersed in distilled water and nanoparticles dried on glass slide. Besides, hydrogel was prepared via solvent exchange method. Antibacterial activity of samples was tested against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by %reduction under ASTM E2149-10. It was found that CTCMA after fabrication into nanoparticles and hydrogels did not exhibited antibacterial activities. This might due to the hydrolysis of ester linkage during fabrication. Besides, the antibacterial activity of CTCMA nanoparticles dried on glass slide was also evaluated under AATCC100. It was found that CTCMA showed antibacterial activity against S. aureus around 14.62%. Degradation of CTCMA and CT hydrogels were investigated against lysozyme. CTCMA showed faster degradability than unmodified chitin. Explained from X-ray diffractogram of CTCMA, it represented crystallinity index about 68.79% which less than CT that represented about 82.94%. Thus, quaternary ammonium chitin could be applied for antibacterial biomedical applications. But, it has to be fabricated into ready to use applications instantly after synthesis for preserving its antibacterial activity.