# Formulation of Boron Encapsulated Smart Nanocapsules for Targeted Drug Delivery to the Brain
## 3 Results
### Preliminary Cell Studies
#### 3.3.3 Permeation Studies  
Permeation and uptake assays are carried out as part of one assay. First, for permeation, CaCo2 cells are plated onto transwell plates. Once plated, they are allowed to grow to about 80% confluence. The trans-epithelial electrical resistance (TEER) is measured. Readings of between 500 and 600 ohms are obtained; cells are treated with nanoparticle samples. Once these cells are treated with a sample, at different time points cells were lysed and  
Figure 19: Toxicity of different concentrations of DLC functionalised carbamenes on CaCo2 and U-87 MG cells after 24 h. Assays were repeated five times, with each assay containing triplicate readings for the same concentrations. Toxicity studies were performed at different concentrations for compound 2 (TPP), compound 4 (NB), and compound 6 (PS). Figure 18: Uptake of boron for 3-carboranylpropyl) (3,7-diamino-5-phenylphenazin-5-ium) bromide (6) into CaCo2 and U87 MG cells after 1, 6 and 24 h.  
measured via an ICP-MS for boron concentrations, Figure 20 shows that permeation of the nanoparticles occurred through the cellular monolayer and into the receiver compartment. Figure 21 shows the permeation studies of the PPY-CHIT NC entrapped with the boron derivatives previously mentioned. The results below indicate that an increased amount of boron was taken up into the cells as time passed. This is apparent for all NC preparations except for the Nile blue derivative; the reasoning behind this is that some of the boron may have permeated into the cells, therefore, reducing the amount of boron free within the receiver compartment. Figure 21: Boron concentration of compounds that have permeated through the cellular monolayer for nanocapsules (NC) formulated with chitosan and polypyrrole. Boron concentration for permeated boron was undertaken on compound 2 (TPP), compound 4 (NB), and compound 6 (PS). Figure 20: Boron concentrations of the compound that has permeated through a cellular monolayer from nanoparticles (NP) formulated through ionotropic gelation. Boron concentrations for permeated boron were undertaken for compound 2 (TPP), compound 4 (NB), and compound 6 (PS). to its capabilities in tumour targeting. In addition, it represents favourable physiochemical characteristics such as being biodegradable, biocompatible, hypoallergenic, FDA-approved, and safe to use. The copolymerisation of chitosan with polypyrrole was also introduced in this study; polypyrrole has been shown to have favourable characteristics in terms of safety, stability, high conductivity, and pH-responsive activity releasing the drug at more tumour specific regions [42]. PPy becomes conductive at lower pH values due to the protonation of the amine group, which makes it ideal for targeting cancer regions, as they are known to be lower in pH compared to normal healthy cell environments. This triggers the release of the encapsulated drug, while chitosan acts as a carrier. This formulation, in turn, would have the potential to transform cancer treatments due to overall improvement in treatment efficacy [43]. The size of the PPy-CHIT nanocapsules (NC), with and without pharmacophore, ranged from 440 to 500 nm (Figure 11), with an average encapsulation efficiency of 85%. The decrease, with the NC loaded with pharmacophore vs. non-drug-loaded, may be explained due to the pyrrole forming potential bonds with the boron moieties. This is particularly advantageous, as the smaller sizes are preferred in order to permeate the blood-brain barrier (BBB). The surface charge profiles (Figure 12) for the NC ranged from 37.9 to 39.2 mV for pharmacophore encapsulated NC. The surface charge was slightly lower for non-pharmacophore-loaded NC, giving a value of 37.2 mV, which is expected, as was previously explained. There are a number of alterations that may be required for the nanodelivery systems to be more effective.