26
nanoparticles surrounded by reactive oxygen species (ROS) were responsible for
inflammation (Li et al. 2010). Because of these undesirable effects, the surface of
nanomaterials of this kind is coated and their toxicity is controlled. Connor et al.
showed that spherical gold nanoparticles coated with various coatings showed no
toxicity response (Connor et al. 2005). Their stability was also enhanced via coating
with a suitable material (Kirchner et al. 2005). Scientists have claimed that CdSe
quantum dots have substantial cytotoxicity because of their surface oxidation and
Cd
2+
ions releasing. Cd
2+
ions are carcinogenic to human cells. If the quantum dots
are encapsulated with the ZnS, the decrease of the cell viability tended to diminish
about 66%. But, encapsulation of quantum dots with 98% bovine serum albumin
reduces this rate almost to zero (Derfus et al. 2004). In another study, ZnS and CdSe
quantum dots were coated with mercaptoundecanoic acid and sheep serum albumin
and their cytotoxicity in vitro was investigated. Scientist exposed human hepatocytes, primate kidney, and cervical cancer cells to these quantum dots and determined a decrease in the cell viability (Shiohara et al. 2004).
Hydrophilicity and hydrophobicity are clear to have a great impact on the interaction of nanomaterial’s behavior. Hydrophilicity and hydrophobicity are measures
of spreading water on materials. If water spreads across material easily and in turn
contact angle is less than 90°, the material is said to be hydrophilic and loving water.
If the water molecules show resistance to spreading, then water almost forms a
droplet dwelling on the surface of material and thereby the contact angle is bigger
than 90°; the material does not love water and is called hydrophobic material. An
interesting phenomenon of nature using nanostructures is the lotus effect (Karthick
and Maheshwari 2008). As can be experienced, leaves of the lotus plant are always
clean. This is due to hydrophobic property of leaves which protects them against
moisture. Each drop of water can remove hydrophilic dust from the leaves. It is
crystal clear that when hydrophobic material is in water, these non-polar molecules
tend to clump up together in order to achieve minimal contact with water molecules.
Thus, nanoparticles should exhibit hydrophilic behavior in order to be well dispersed in water or serum media, while hydrophobicity is required in material–cell
interaction. The dispersion of particles can be provided by using hydrophilic functional groups attachment (Fratoddi 2018).
It is well known that solubility is tightly dependent on the interaction between
solvent and solute. A strong attraction between them means higher solubility while
a weak attraction means lesser solubility. In general rule, like dissolves like. It
means that polar solutes tend to dissolve in polar solvent while non-polar one dissolves in non-polar solvent. Another factor influencing solubility is common ion,
which decreases the solubility. However, temperature and pressure have a strong
impact on solubility; this is out of scope of this chapter. The importance of solubility
becomes apparent when considering blood. Because blood mainly consists of water,
medicines used should be polar in order to play their roles. Furthermore, their circulation period in bloodstream is longer since their recognition as intruder by immune
system is weakened. This is why hydrophobic materials are modified by hydroxylation, amination, or other way. Thus, materials can be used in drug delivery in a
more efficient way (Rašović 2017).
S. Tekmen and S. Öksüz
nanoparticles surrounded by reactive oxygen species (ROS) were responsible for
inflammation (Li et al. 2010). Because of these undesirable effects, the surface of
nanomaterials of this kind is coated and their toxicity is controlled. Connor et al.
showed that spherical gold nanoparticles coated with various coatings showed no
toxicity response (Connor et al. 2005). Their stability was also enhanced via coating
with a suitable material (Kirchner et al. 2005). Scientists have claimed that CdSe
quantum dots have substantial cytotoxicity because of their surface oxidation and
Cd
2+
ions releasing. Cd
2+
ions are carcinogenic to human cells. If the quantum dots
are encapsulated with the ZnS, the decrease of the cell viability tended to diminish
about 66%. But, encapsulation of quantum dots with 98% bovine serum albumin
reduces this rate almost to zero (Derfus et al. 2004). In another study, ZnS and CdSe
quantum dots were coated with mercaptoundecanoic acid and sheep serum albumin
and their cytotoxicity in vitro was investigated. Scientist exposed human hepatocytes, primate kidney, and cervical cancer cells to these quantum dots and determined a decrease in the cell viability (Shiohara et al. 2004).
Hydrophilicity and hydrophobicity are clear to have a great impact on the interaction of nanomaterial’s behavior. Hydrophilicity and hydrophobicity are measures
of spreading water on materials. If water spreads across material easily and in turn
contact angle is less than 90°, the material is said to be hydrophilic and loving water.
If the water molecules show resistance to spreading, then water almost forms a
droplet dwelling on the surface of material and thereby the contact angle is bigger
than 90°; the material does not love water and is called hydrophobic material. An
interesting phenomenon of nature using nanostructures is the lotus effect (Karthick
and Maheshwari 2008). As can be experienced, leaves of the lotus plant are always
clean. This is due to hydrophobic property of leaves which protects them against
moisture. Each drop of water can remove hydrophilic dust from the leaves. It is
crystal clear that when hydrophobic material is in water, these non-polar molecules
tend to clump up together in order to achieve minimal contact with water molecules.
Thus, nanoparticles should exhibit hydrophilic behavior in order to be well dispersed in water or serum media, while hydrophobicity is required in material–cell
interaction. The dispersion of particles can be provided by using hydrophilic functional groups attachment (Fratoddi 2018).
It is well known that solubility is tightly dependent on the interaction between
solvent and solute. A strong attraction between them means higher solubility while
a weak attraction means lesser solubility. In general rule, like dissolves like. It
means that polar solutes tend to dissolve in polar solvent while non-polar one dissolves in non-polar solvent. Another factor influencing solubility is common ion,
which decreases the solubility. However, temperature and pressure have a strong
impact on solubility; this is out of scope of this chapter. The importance of solubility
becomes apparent when considering blood. Because blood mainly consists of water,
medicines used should be polar in order to play their roles. Furthermore, their circulation period in bloodstream is longer since their recognition as intruder by immune
system is weakened. This is why hydrophobic materials are modified by hydroxylation, amination, or other way. Thus, materials can be used in drug delivery in a
more efficient way (Rašović 2017).
S. Tekmen and S. Öksüz