# Polymeric Nanoparticles--Tools in a Drug Delivery System in Selected Cancer Therapies
## 3 Nanoparticles in Cancer Therapy--Passive and Active Mechanisms
### Passive Mechanism
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Methods of Formulation** & **Description** & **Advantages** & **Disadvantages** & **Example** & **Cancer** & **Ref.** \\ \hline \multirow{4}{*}{Nanoprecipitation} & Use of two mixing solutions, which results in the displacement of solvent and precipitation of nanoparticles & Single step Formulation of nanospheres and nanocapsules (\(\sim\)200 nm) & Only hydrophobic drugs can be encapsulated Solvent residues & BLC-PTX-loaded D,L-PLGA & Human lung cancer & [7; 24; 25; 26; 27] \\ \hline \multirow{4}{*}{S Solvent evaporation} & PNPs are obtained by evaporation of the solvent from the polymer followed by diffusion through the continuous phase. Single or double emulsion can be carried out & Requires homogenizer and heating nanospheres & Residual solvent may remain For lipid-dissolved drugs & NPs & lines & \\ \hline \multirow{4}{*}{Salting out} & Water with salt is rapidly added to a polymer solution with a drug and a water-soluble solvent, leading to the diffusion of the solvent and the nonaparticles of nanoparticles & For heat-sensitive drugs No heating required Encapsules & Only for lipophilic drugs & Meloxicam-loaded D,L-PLGA & Human colorectal cancer & [7; 19; 26; 28] \\  & Uses a dialysis tube inside which a polymer dissolved in a solvent. & For heat-sensitive drugs No heating required Encapsules & Tabitizer removal required & NPs & lines & \\ \hline \multirow{4}{*}{Dialysis} & Uses a dialysis tube inside which a polymer dissolved in a solvent. & Simplicity Easy & Time-consuming poly does not require (N-vinyl-caprolactone) & DTX-loaded D & \multirow{4}{*}{TNNC [3; 11; 20]} \\  & Suspension of nanoparticles results in displacement of the solvent & Singularity Easy manipulation of nanoparticle size & Does not require advanced equipment & & \\ \hline \multirow{4}{*}{Supercritical fluid technology} & In this method, supercritical liquid is used and is based on two phenomena: the rapid expansion of the supercritical solution and the rapid expansion of the supercritical solution into the solvent & High purity of nanoparticles & & \\ \hline \hline \multirow{4}{*}{BLC–basiclein; PTX—paclitaxel; D,L-PLGA—poly(D,L-lactide-co-glycolide); NPs—nanoparticles; PNPs—polymer nanoparticles; DTX—dooctavelæ; FA—folic acid; TNBC—triple-negative breast cancer; CXB—elecoxib.} & \\ \cline{1-1} \cline{2-5}  & BLC–basiclein; PTX—paclitaxel; D,L-PLGA—poly(D,L-lactide-co-glycolide); NPs—nanoparticles; PNPs—polymer nanoparticles; DTX—dooctavelæ; FA—folic acid; TNBC—triple-negative breast cancer; CXB—elecoxib. & \\ \hline \end{tabular}
\end{table} 
Table 2: Top-down techniques for formulation of polymeric nanoparticles. into the tumor is limited [21; 23; 33]. In addition, it is acknowledged that the targeted action of PNPs through the EPR effect does not allow for the reduction in toxicity and triggering of side effects (Figure 4) [26; 34; 35]. One example of nanoformulation based on a passive mechanism is the Genexol PM\({}^{\text{\textregistered}}\) product, comprising Monomethoxy-poly (ethylene glycol)-_block_-poly(d,l-lactide) loaded with paclitaxel at a dose of 30 mg. Currently, its use is approved in South Korea for the treatment of metastatic breast cancer, while in the USA it is under phase II clinical trials as a potential pancreatic cancer drug [22].