Engineering, 2012, 5, 103-105
doi:10.4236/eng.2012.410B026 Published Online October 2012 (http://www.SciRP.org/journal/eng)
The Modification of Poly amidoamine (PAMAM-G0.5) by
Cytosine
Omid Louie*, A bdolhossien Massoudi, Hooshang Vahedi, Hajar Asadi, Sami Sajja difa r
Ch emistry Department, Payame Noor Uni vers ity, Mashhad, Iran
Received 2012
ABSTRACT
The half generation Poly(amidoamine) (PAMAM) dendrimers was synthesized and characterized and modification by heterocyclic
DNA base (Cytosine) . The conjugated Cytosine modified detected by FT-IR, 1H NMR, 13C NM R and Mass spectroscopy analysis.
Keywords: Component; Polyamidoamine; PAMAM; Cytosine
1. Introduction
Dendrimers are molecules with three-dimensional structure of
certain branches around a central core which were synthesized
by processing stage or repeated synthesis. Also dendrimers
have been identified alike the arborols, starburst, ascade and
Cauliflower polymers. Dendrimers are Unique molecular
structure of polymer materials like balls that contain a Initiator
core, rep eat units and Surface ter minal gro up. Those are spher-
ical configuration in high Generation. For the first time we have
inventived new models for determination molecular weight
dendrimers AB2-type [9,12]. Dendrimer polyamidoamine
(PAMAM) as one of commercial ones [10,13] due to the con-
trollable mass, the water solubility, and the possibility of sur-
face functionality, has been widely used in the biomedical and
genetics [10]. The large numbers of surface functional groups
on dendrimer’s outer shell can be modified or conjugated with a
variety of interesting guest molecules [11,14]. PAMAM was
modified by different molecules ,in this study PAMAM was
modified to cytosine. The modification PAMAM molecule
properties is changed proportion to PAMAM molecule, in
hence modification PAMAM can be conjugated with targeting
molecules, dyes and drugs for different usage in science [5-8].
2. Exp erimenta l Pro cess
2.1. Synthesis PAMAM Dendrimers Half Generation
(G0.5) , EDA Core (PA-
MAM(G0.5)-EDA(Core),Z0=2)
The Synthesis PAMAM dendrimers half generation (G0.5),
EDA Core (PAMAM(G0.5)-EDA(Core),Z0=2) A solution of
freshly distilled 1,2-diaminoethane (5 g, 5.5 ml, 0.083 mol) in
methanol (20 ml) was added dropwise to a stirred solution of
methylacrylate (35 g, 37 ml, 0.407 mol) in methanol (20 ml),
under nitrogen, over a period of 2 h. The final mixture was
stirred for 30 min at 0°C and then allowed to warm to room
temperature and stirred for a further 24 h. The solvent was re-
moved under reduced pressure at 40°Cusing a rotary evapo-
rator and the resulting yellow oil viscose under vacuum (10-1
mm Hg, 50°C) overnight to give PAMAM(G0.5)-EDA(Core
(a) , the final product (3.64 g, 91.5%). The synthesis (a) in
Figure 1 is shown. 1738 cm -1 is ester C=O stretchi ng absorp-
tion.13C-NMR ester groups carbon has appeared in 173.4 ppm.
1 H-NMR ester methyl group protons was appeared in 2.51
ppm. Full spectral data and characterizations (a) is given in
Table 1.
2.2. Conjugated of Cytosine with G0.5 PAMAM
Dendrimer
Cytosine (4.5 mmol) was dissolved in H2O at PAMAM(G0.5)-
EDA(Core)(a) (4.95 mmol) was di ssolved in MeOH, Then was
added drop wise to the cytosine solution, at a molar ratio of
cytosine/(a) ,4:1. After complete addition the mixture was
stirred for 48h at room temperature and the resultant light yel-
low solid vacuum dried (10-1 mm Hg, 50°C) overnight to give
the cytosine with PAMAM-EDA(Core) (b) (71.9%). It was
detectab le by FT-IR, 1H NMR, 13C NMR, and Mass spectr os-
copy analysis. The synthesis (b) in Figure 2 is shown.
3. Results and Discussion
FT-IR spectra (a) ,(b) and cytosine was shown in Figure 3 i, ii,
iii respectively. ester groups absorption in 1735.8 cm-1 which
not presented in the cytosine spectra (Figure 4 iii) whereas
disappeared thoroughly in (b) (Figure 4 ii). at CH2 groups
anti-symmetrical stretching was obtained (a) at 2954 cm-1. of
–NH and stretching vibrations was shown at 3285 cm-1 (Fig-
ure 4i). –NH stretching vibrations amide was shown at 1648
H
2
NNH
2
CO
2
Me
NNCO
2
Me
CO
2
Me
MeO
2
C
CO
2
Me
MeOH
Figure 1. Synthesis PAMAM (G 0.5) .
*Corresponding author.

Engineering, 2012, 5, 103-105
doi:10.4236/eng.2012.410B026 Published Online October 2012 (http://www.SciRP.org/journal/eng)
Table 1. Spectral mode assignment for a , b and Cytosin.
Spectral data PAMAM G0.5 Cytosine PAMAM G0.5(Cyt.)4
FT-IR (cm-1)
C=O s tr etc hing vibration ester groups 1 735 C=O Stretching vibration amide 1 725 C=O Stretching vibration amide 1566
C-O stretching ester groups 1 203 C=N str etc hing vibration 1666 N-H bending vibration amide 1234.4
C-N stretching vibrati on amine groups 1041 C-N stretching vibrati on 1234 C-N stretching vibration 1651
13CNMR (ppm)
C=O 173.1 C=O 166.9 C=O (core) 176.9
C-C=O C-NH2 C-NH-C=O 164.7
CH3 32.6
51.9 C-NH-C=O 171 158.1
1HNMR (ppm) CH2-C=O 2.46 CH (ring) 5.62 CH2-C=O 2.28
CH3(end group s) 3.64 NH-C=O (new bond) 7.3
Mass (m / z) 4 04 111 483-564-644-720
+H2O,
MeOH C
4
O
N
N
H
NH
O
Cytosine DendrimerG0.5
Figure 2. Synthesis PAMAM-EDA(Core)-Cytosin (b).
(i)
(ii)
(iii)
Fi g ure 4. FT-IR spectral (a), (b) and Cytosine in this figure; i, ii, iii
respectively.
cm-1 and 1558 cm-1 for amide I & II respectively. Also N–H
bending vibrations amide was shown at 1648 and 1558 cm-1.
Spectral data and characterizations (a), (b) and cytosine are
given in Table 1.
4. Conclusions
In summary, conjugating cytosine with half generation of
PAMAM dendrimer was successfully synthesized and charac-
terized. PAMAMG0.5-Cytosine Systematic mass spectral
analysis has shown that nearly theoretical masses are obtained
for product (b)( or the mass spectra of this compound displayed
molecular ion peaks at the appropriate m/z values or mass
spectra on the other hand, give precise molecular weight infor-
mation to compare with mathematically predicted molecular
masses.), mass spectrometry of that gave a mass of 720 m/z
(theoretical mass: 724m/z). Overall the spectral data clearly
indicate the desired cytosine with PAMAM-EDA(Core) (b) is
formed.
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