Evaluation of the mucoadhesive properties of chitosan nanoparticles prepared using different chitosan to tripolyphosphate (CS:TPP) ratios.

Mucoadhesive molecules such as chitosan, can allow targeting of a particular tissue to prolong residence time and subsequently improve bioavailability. The purpose of this study was to investigate chitosan-tripolyphosphate (CS:TPP) nanoparticles and to evaluate the interaction between nanoparticles of different CS:TPP ratios with mucin using viscosity, particle size analysis and ζ-potential. For all CS:TPP ratios examined, a minimum value of viscosity was reached for a 3:1 CS:TPP ratio, however chitosan nanoparticles at this ratio were not stable (<+30 mV), whereas a CS:TPP ratio of 4:1 displayed the strongest interaction. This suggests a minimum CS:TPP ratio of 4:1 is required to produce stable nanoparticles able to form strong interactions, which is consistent with a greater mucin binding efficiencies at CS:TPP ratios of 4:1 and higher, which were quantified using a colorimetric assay. Further analysis of similar systems could lead potentially to tuneable chitosan nanoparticles for specific applications.

Designing chitosan-tripolyphosphate microparticles with desired size for specific pharmaceutical or forensic applications.

Chitosan (CS) is a natural cationic polymer obtained by the partial N-deacetylation of chitin. Chitosan microparticles can be prepared by cross-linking with tripolyphosphate (TPP) via the ionic interaction between positively charged amino groups (CS) and negatively charged counter ions (TPP). This can be controlled by the charge density of CS and TPP, which depend on the pH and ionic strength of the solution. The purpose of this study is to investigate the combined effects of three independent variables (pH, ionic strength and CS:TPP ratio) on three important physico-chemical properties (viscosity, zeta potential and particle size) during the preparation of microparticles. CS:TPP microparticles were prepared using experimental design and equations were generated and used to predict relative viscosity, zeta potential and particle size under different conditions. This gives us the ability to design tuneable CS-TPP microparticles with desired size for specific pharmaceutical or forensic applications e.g. latent fingerprint visualisation.