Combinatorial-designed Hyaluronic Acid Nanoparticles for Tumour Targeted Drug and Small Interfering Ribonucleic Acid Delivery - Hyaluronic Acid for Biomedical and Pharmaceutical Applications - page 91

treatment of the estimation of solid surface free energy by selective
wetting measurements are described in detail in our review article [6].

The dispersive component of the surface energy c can be calculated
from the retention time obtained from iGC measurements of a series
of n-alkane probes injected at infinite dilution (concentration within
the Henry´s portion of the adsorption isotherm) [8]. Two approaches
are used for the evaluation of these dependencies, the first one
according to Schultz and co-workers [9] Equation 4.1 and the second
one according to Dorris and Gray [10] Equation 4.2 :

D D

1 2 / 1 2 /

` j ` j

RT In V = a 2 N + C

(4.1)

c c

N A

Where:

T: Absolute temperature;
a : Cross sectional area of the probe molecule;
ln: Natural logarithm;
R : Universal gas constant;
N A : Avogadro´s number;
D

c : Dispersive component of surface free energy of the liquid probe;

c : Dispersive component of the surface free energy of the solid;
V N : Retention volume; and
C : A constant.

S

D

RT In V / V

^ h

N C H N C H

=

^ ^ h

(4.2) c

n + 1 2 n + 4 n 2 n + 2

4 A N a

2 2

c CH CH

2 2

Where:

a CH 2 : Surface area of a CH 2 unit (~0.6 nm 2 );
n : Number of carbon atoms in alkane probes; and
γ CH 2 : Free energy (approximately 35.6 mJ/m 2 ).