## 4 Nanotechnology and Cancer
### Targeting Strategies  
Nanoparticles hold the transformative potential to innovate the diagnosis and treatment of various diseases, including enabling the accurate targeted delivery of drugs to cell types [39]. Progress in the engineering of nanoparticles and a deeper comprehension of the significance of characteristics like size, shape, and surface properties for biological interactions are paving the way for new prospects in the development of therapeutic nanoparticles [39]. NPs can be tailored to target cancer cells in several ways. Passive targeting exploits the Enhanced Permeability and Retention (EPR) effect, which is due to the irregular vasculature and inadequate lymphatic drainage in tumors, facilitating the accumulation of nanoparticles in tumor tissues [40; 41]. Active targeting involves modifying the surface of NPs with molecules that can bind specifically to receptors overexpressed on cancer cells. The first obstacles faced are largely determined by the preferred method of administration. The extent to which each of these administration methods can be successfully used is significantly impacted by the characteristics of the nanoparticle [42]. Managing the particle size, surface characteristics, and release profiles of bioactive compounds is the major objective when building nanoformulations to ensure the site-targeted accumulation and activity of pharmaceuticals at the theraputically ideal rate and dose regimen. Nanoformulations, which are typically 10-200 nm in diameter, are made by either encapsulating pharmaceuticals inside the nanocarriers or complex medications with the nanocarriers by covalent bonding to enhance the characteristics of the bioactive chemicals. To increase the bioavailability, solubility, extended blood circulation, and targeted delivery of medications while reducing their negative effects, these NFs have been used in drug delivery studies. Nanoformulations may interact with biological systems when ingested, injected, skin-penetrated, or inhaled into the body. Loading drugs is a crucial approach in drug delivery. An effective nanodelivery system should possess substantial drug-loading capabilities, enabling a reduction in the required amount of matrix materials for delivery. Two primary methods are employed for drug loading. The first is the incorporation method, where the drug is integrated during the nanoparticle formulation process. The second is the adsorption/absorption method, where the drug is absorbed after nanoparticle creation by immersing the nanocarrier in a concentrated drug solution. The effectiveness of drug loading and entrapment is contingent upon the solubility of the drug in the excipient matrix material, which is influenced by various factors, such as molecular weight, matrix composition, interactions between the drug and matrix, and the existence of end functional groups in either the drug or matrix [43]. Loading macromolecules, pharmaceuticals, or proteins into nanoparticles at or near their isoelectric point maximizes loading efficiency, as indicated by studies [42]. Ionic contact between the drug and matrix materials enhances drug loading for small molecules. When developing a nanoparticle delivery system, careful consideration of both drug release and polymer biodegradation is essential. Various factors collectively influence the rate at which the drug exits the body, including the drug's solubility, desorption of surface-bound or adsorbed drugs, drug diffusion through the nanoparticle matrix, and degradation or erosion of the nanoparticle matrix. The delivery mechanism is controlled by considering the solubility, diffusion, and biodegradation of the particle-matrix. In the context of nanotechnology, matrix diffusion or erosion is the mechanism through which drug release occurs when the medication is evenly dispersed. If the drug's diffusion is more rapid than the matrix's erosion, then a diffusion process is mostly in charge of the release mechanism.