In-vitro evaluation of the effect of polymer structure on uptake of novel polymer-insulin polyelectrolyte complexes by human epithelial cells

Biocompatible disulphide cross-linked sodium alginate derivative nanoparticles for oral colon-targeted drug delivery

The application of layer-by-layer (LbL) approach on nanoparticle surface coating improves the colon-specific drug delivery of insoluble drugs. Here, we aimed to formulate a self-assembled cysteamine-based disulphide cross-linked sodium alginate with LbL self-assembly to improve the delivery of paclitaxel (PCX) to colonic cancer cells. Cysteamine was conjugated to the backbone of oxidized SA to form a core of self-assembled disulphide cross-linked nanospheres. P3DL was selected for PCX loading and fabricated LbL with poly(allylamine hydrochloride) (PAH) and poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSCMA) resulting from characterization and drug release studies. P3DL-fabricated PCX-loaded nanospheres (P3DL/PAH/PSSCMA) exhibited an encapsulation efficiency of 77.1% with cumulative drug release of 45.1%. Dynamic light scattering analysis was reported at 173.6 ± 2.5 nm with polydispersity index of 0.394 ± 0.105 (zeta potential= -58.5 mV). P3DL/PAH/PSSCMA demonstrated a pH-dependent swelling transition; from pH 1 to 7 (102.2% increase). The size increased by 33.0% in reduction response study after incubating with 10 mM glutathione (day 7). HT-29 cells showed high viabilities (86.7%) after treatment with the fabricated nanospheres at 0.8 µg/mL. Cellular internalization was successful with more than 70.0% nanospheres detected in HT-29 cells. Therefore, this fabricated nanospheres may be considered as potential nanocarriers for colon cancer-targeted chemotherapeutic drug delivery.

Synthesis and characterisation of mucoadhesive thiolated polyallylamine

The thiolation of polyallylamine (PAAm) for use in mucoadhesive drug delivery has been achieved. PAAm was reacted with different ratios of Traut's reagent, yielding products with thiol contents ranging from 134-487μmol/g. Full mucoadhesive characterisation of the thiolated PAAm samples was conducted using swelling studies, mucoadhesive testing on porcine intestinal tissue and rheology. Both swelling and cohesive properties of the thiolated PAAm products were vastly improved in comparison to an unmodified PAAm control. The swelling abilities of the thiolated samples were high and the degree of thiolation of the products affected the initial rate of swelling. High levels of mucoadhesion were demonstrated by the thiolated PAAm samples, with adhesion times of greater than 24h measured for all three samples and, thus, thiol content did not appear to influence mucoadhesion. Rheological studies of the thiolated PAAm samples showed an increase in G' and G″ values upon the addition of a mucin solution which was not observed in the unmodified control, again highlighting the mucoadhesive interactions between these thiolated polymers and mucin. The synthesis of thiolated PAAm by reaction with Traut's reagent and resulting mucoadhesive properties demonstrates its potential for use a mucoadhesive drug delivery device.