# Targeted Delivery Strategies for Hydrophilic Phytochemicals
## 2 Delivery Systems for Hydrophilic Phytochemicals
### Polymeric Nanoparticles  
Polymeric nanoparticles (Figure 2) are defined as colloidal systems composed of polymers. They are divided into nanocapsules and nanospheres. Nanospheres consist of a solid core and polymeric matrix within which active molecules are encapsulated. In the case of nanocapsules, the active compound is entrapped in an inner liquid or solid core secured by polymeric membrane, which is composed of non-ionic surfactants, phospholipids and macromolecules. Active ingredients could be encapsulated or adsorbed on the polymers surface [52; 53; 54; 55; 56]. Polymeric nanoparticles hold scientific interest, because, similarly to liposomes or niosomes, they could deliver hydrophilic substances. Nanocapsules could have inner water or oil core, within which active ingredients could be solubilized this gives higher drug encapsulation compared to nanospheres. In nanospheres, the active molecule is entrapped in matrix of polymer (Figure 2) [54; 57; 58]. Table 1 provides short comparison of the selected carriers. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Group** & **Structure** & **Size** &
\begin{tabular}{c} **Preparation/Isolation** \\ **Methods** \\ \end{tabular} & **Advantages** & **Limitations** & **References** \\ \hline \multirow{11}{*}{Liposomes} & & & - film hydration & & & \\  & & - reverse phase evaporation & - biocompatible & & \\  & & - solvent injection & - biodegradable & - high cost of production & \\  & & - heating method & - high bioavailability & - low solubility & \\  & Phospholipid bilayer & - SUV (20-200 nm) & - microfulfide channel & - low toxicity & - possible instability & \\  & (SUV, LUV, GUV) or & - LUV (200 nm-1 μm) & - supercritical fluidic & - low immunogenicity & (e.g., during storage) & \\  & several lipid bilayers & - GUV (>1 μm) & - freeze-drawing & - both hydrophilic and & - possible degradation via \\  & (MLV, MVV), & - MLV (100 nm-1 μm) & - freeze-drying & hydrophobic compounds & hydrolysis or oxidation \\  & hydrophilic core & - MLV (> 500 nm) & - detergent removal & delivery & - possible encapsulated & \\  & & - MVV (>1 μm) & - membrane extrusion & - controlled release of the of & drug leakage & \\  & & - sonication & active compounds & - special storage conditions & \\  & & & - micro-emulsification & - targeting delivery & are required & \\  & & & - dual asymmetric & - extension of drug half-life & \\  & & & - centrifuge & & \\ \hline \multirow{11}{*}{Nosomes} & & & - thin film hydration & & & \\  & & - reverse phase evaporation & - lower cost of production & & \\  & & - either injection (solvent) & - biocompatible & & \\  & & - emulsion method & - biodegradable & & \\  & & - lipid injection & - low toxicity & - low physical stability & \\  & & - bubble method & - low immunogenicity & - possible degradation via & \\  & & - microfidisation method & - both hydrophilic and & - hydrolysis & hydrolysis & \\  & & bilayer in & - SUV (100-100 nm) & - supercritical reverse phase & hydrophobic compounds & - possible aggregation & \\  & conjunction with & - MLV (>10 μm) & evaporation & - directive & - possible encapsulated & \\  & cholesterol & - MLV (>10 μm) & - micelle solution & - improved chemical stability & - drug leakage & \\  & & & and enzyme & - structurally flexible & - possible aggregation & \\  & & & - trans membrane pH & -controlled release of active & - limited shelf-life & \\  & & & gradient drug & compounds & \\  & & & uptake process & - targeting delivery & \\  & & & - formation from & - special storage conditions & \\  & & & pronisosomes & are not required & \\  & & & - sonication & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Brief characteristics of the selected carriers for hydrophilic phytochemicals.