Amelioration of Blood Compatibility and Endothelialization of Polycaprolactone Substrates by Surface-Initiated Atom Transfer Radical Polymerization - Advances in Biomaterials Science and Biomedical Applications - page 187

with the presence of the alkyl bromide species [41] (Fig. 3d'). The alkyl bromide-immobi‐
lized PCL surface became more hydrophobic, as static water contact angle increased noticea‐
bly to 85 ± 3 o (Table 1).

Sample GY g (μg/cm 2 )

( mean± SD h )

[Br]/[C] i [N]/[C] i Surface composition j

(molar ratio)

WCAk
(degree)

Pristine PCL a - - - [C-H]:[C-O]:[O=C-O]

= 5:1.1:1.0 (5:1:1)

93±2

PCL-NH 2 b - - 0.043 [C-H]:[C-N]:[C-O]:[O=C-O]

= 4.7:0.7:1.1:1.0

66±3

PCL-Br c - 3.17×10 -2 - [C-H]:[C-N]:[C-O/C-Br]:[O=C-O] =

5.0:0.9:1.7:1.0

85±3

PCL- g -P(GMA)1 d 6.31±1.32 9.29×10 -3 - [C-H]:[C-O]:[O=C-O]

= 3.8:2.8:1.0 (3:3:1)

62±4

PCL- g -P(GMA)2 e 14.76±2.63 4.72×10 -3 - [C-H]:[C-O]:[O=C-O]

= 3.1:3.0:1.0 (3:3:1)

61±5

PCL- g -P(GMA)1- c -
gelatin f

2.63± 0.52 - 0.169 [C-H]:[C-N]:[C-O]:[O=CNH]: [O=C-

O] = 3.5:1.5:1.7:1.0:0.7

37±3

PCL- g -P(GMA)2- c -
gelatin pala

3.79±0.73 - 0.203 [C-H]:[C-N]:[C-O]:[O=CNH]: [O=C-

O] = 3.1:1.5:1.4:1.0:0.3

35±4

a Pristine PCL refers to the cleaned PCL film after rigorous wasing with alcohol/water solution and deionized water, b
PCL-NH 2 was obtained after 1 h of aminolysis in a 10% (w/w) 1,6-hexanediamine/isopropanol solution at 40 o C, c PCL-
Br was obtained after the PCL-NH 2 surface reacted with 2-bromoisobutyryl bromide (BIBB) in dried hexane containing
1:1 (molar ratio) BIBB and triehtylamine (TEA), d,e Reaction conditions: [GMA]:[CuBr]:[CuBr 2 ]:[bpy]=100:1:0.2:2 in meth‐
anol-water solution (1:1, v:v) at room temperature for 1 and 3 h to produce the PCL- g -P(GMA)1 and PCL- g -P(GMA)2
surfaces, respectively, f Reaction conditions: the PCL- g -P(GMA)1 and PCL- g -P(GMA)2 surfaces incubated in PBS (pH 7.4)
solution containing the gelatin at a concentration of 3 mg/mL at room temperature for 24 h, g GY denotes the graft‐
ing yield, and is defined as GY = (W a - W b )/A, where W a and W b corresponds to the weight of the dry films before and
after grafting of polymer brushes, respectively, and A is the film area (about 3.2 cm2
), h SD denotes standard deviation, i Determined from the corresponding sensitivity factor-corrected element core-level
spectral area ratios, j Determined from the curve-fitted C 1s core-level spectra. Theoretical values are shown in paren‐
theses. k WCA denotes static water contact angles.

Table 1. Grafting yield, surface composition, and water contact angles of the pristine PCL and surface-functionalized
PCL surfaces

3.2. Surface-initiated ATRP of GMA and immobilization of gelatin

P(GMA) is an effective surface linker to immobilize biomolecules, such as proteins, antibod‐
ies or enzymes, for tissue engineering applications [42]. Fig. 4 shows the respective wide
scan, C 1s and Br 3d core-level spectra of the PCL- g -P(GMA) surface from 1 and 3 h of ATRP
reaction. The C 1s core-level spectra of the PCL- g -P(GMA) surface can be curve-fitted into
three peak components with BEs at 284.6, 286.2 and 288. 7 eV, attributable to C-H, C-O and
O=C-O, respectively (Figs. 4b and 4d). For the PCL- g -P(GMA)1 surface from 1 h of ATRP,