Experiment with dual 5-FU and Cisplatin loading in PAMAM dendrimer G3.5-PNIPAM G3.5-PNIPAM was synthesized based on the reaction between PAMAM dendrimer G3.0 –PNIAM which was further mo[r]
Trang 1MINISTRY OF EDUCATION AND
TECHNOLOGY
GRADUATE UNIVERSITY OF SCIENCE AND
TECHNOLOGY
NGUYEN NGOC HOA
IMPROVING THE EFFECTIVE DELIVERY OF
CISPLATIN ANTI CANCER DRUG OF DENDRIMER NANOCARRIER
Field of Study: Polymer and Composite
Code: 9 44 01 25
SUMMARY OF MATERIAL SCIENCE DOCTORAL THESIS
HO CHI MINH, 2020
Trang 2The thesis was completed at
Institute of Applied Materials Science - Graduate University of Science and Technology Vietnam Academy of Science and Technology
Supervisor 1: Prof., Dr Nguyen Cuu Khoa
Supervisor 2: Assoc., Prof., Dr Tran Ngoc Quyen
At hour date month , 2021
The thesis can be found at:
- The National Library of Vietnam
- The Library of Graduate University of Science and Technology
Trang 3INTRODUCTION
1 The necessity of the thesis
Denndrimers were first introduced during the period 1970–1990 by two different groups : Buhleier et
al and Tomalia et al Dendrimers are nano-sized, radially symmetric molecules with well-defined, homogeneous, and monodisperse structure consisting of tree-like arms or branches Dendrimers are nearly mono-disperse macromolecules that contain symmetric branching units built around a small molecule or a linear polymer core Dendrimers are hyperbranched macromolecules with a carefully tailored architecture, the end-groups (i.e., the groups reaching the outer periphery), which can be functionalized, thus modifying their physicochemical or biological properties Dendrimers are designed to drugs delivery to enhance the pharmacokinetics and biological distribution of the drug and to enhance its target ability
Due to their exquisite structure, drug molecules are instantly capped with dendrimer molecules by means of physical adsorption, electrostatic interaction, covalent binding with the peripheral functional groups,
or encapsulating inside the dendrimeric crevices The dendrimeric crevices are usually hydrophobic, which can encapsulate the drug molecule by means of hydrophobic Further, the high density of peripheral groups of multifunctional nature (amine, NH2 or carboxylate COO-) allows to establish electrostatic interaction with drug and then bring them to the target site
Cisplatin is one of the most effective anticancer agents widely used in the treatment of solid tumors It has been extensively used for the cure of different types of neoplasms including head and neck, lung, ovarian, leukemia, breast, brain, kidney and testicular cancers In general, cisplatin and other platinum-based compounds are considered as cytotoxic drugs which kill cancer cells by damaging DNA, inhibiting DNA synthesis and mitosis, and inducing apoptotic cell death However, because of drug resistance and numerous undesirable side effects such as severe kidney problems, allergic reactions, decrease immunity to infections, gastrointestinal disorders, hemorrhage, and hearing loss especially in younger patients, other platinum-containing anti-cancer drugs such as carboplatin, oxaliplatin and others, have also been used Furthermore, combination therapies of cisplatin with other drugs have been highly considered to overcome drug-resistance and reduce toxicity
In the last decade, an alternative strategy following the revolution of nanotechnology has been a shift
in focus from platinum complex design to Cisplatin carriers in order to enhance anticancer activity and reduce its side-effects Among numerous Cisplatin delivery methods, Cisplatin conjugated carriers have been proven
as a promising option Cisplatin can be attached appropriately to the nano-devices containing ester or amide linkages or carboxylate connectivity These interactions can later be hydrolyzed inside the cell allowing drugs
to accumulate in the tumor site Generally, the conjugate between Cisplatin and carriers revealed an improved efficacy of the platinum drug in cancer treatment compared to physical encapsulation
In this thesis, we modify the surface functional groups of PAMAM dendrimers to enhance the drug delivery capacity of these carriers
2 Research purpose
Preparation and characterization of nanocarrier systems for drug delivery system based on the modification of dendrimer (PAMAM) with biocompatible surfaces such as PNIPAM and PAA to improve the capping cisplatin
3 Research content
Trang 4- Synthesizing the derivative PAMAM dendrimer (PAMAM dendrimer - isopropylacrylamide), PAMAM dendrimer - Poly acrylic acid)
Poly(N Evaluating their chemical structure and grafting degree
- Evaluating the capping cisplatin ability of PAMAM dendrimer and their derivative such as PAMAM dendrimer - Poly(N-isopropylacrylamide), PAMAM dendrimer - Poly acrylic acid
- Analyzing the structure of the complex carrier – drug and evaluating the release of cisplatin from carrier
- Identifying the cytotoxicity of PAMAM dendrimer and their derivative
CHAPTER 1 OVERVIEW 1.1 Introduction to dendrimer and biocompatibility of dendrimer
1.1.1 Introduction
The term “dendrimer” was first mentioned by Donald A Tomalia in 1985s The word “dendrimer” is Greek in origin, “Dendron”, by means of tree branch Up to now, various studies have been published about structure of dendrimer molecule, dendrimer synthesis and application of dendrimer in difference fields In general, dendrimers are nano-polymer with spherical morphology and branched structure and have more advantages than that of linear polymer Structure of dendrimers include three part as illustrating in figure 1.1
Figure 1.1 A typical structure of dendrimer
- A dendrimer is comprised of three different parts: (i) central core consisting of atom or the molecule with at least two similar functional groups, (ii) branches, arising from the central atom/molecules core composed by repeat units and the brigde between the terminal functional groups and their core, (iii) numerous terminal functional groups (anion, cation, neutral, hydrophobic or hydrophilic groups) located at the edge of the moleculer which are also called peripheral functional groups
Dendrimer, specialized on PAMAM dendrimer with open open structure, various internal cavities and
Trang 5Dendrimer has been considered as smart carrier because they can help drug to enter to cytoplasm, escape biological barriers, take a longer blood circulation time that enable to create the clinical effect and allow drugs to reach their target sites The primary source of cytotoxicity of PAMAM dendrimers is due to their surface groups Surface groups with amine (-NH2) of PAMAM and PPI dendrimer induce the risk of cell hemolysis depending on the concentration while the charge neutrality terminated dendrimers or anionic terminated surface are found to lower toxicity or non-toxic To increase the biocompability, the possible for target therapy, as well as diminishing their toxic, mainting their exquisite drug delivery feature, the surface of PAMAM dendrimer should be modified with biocompabile and targeting molecules
1.2 Cisplatin anticancer drugs
1.2.1 Properties of Cisplatin
Figure 1.2 Cisplatin drug molecule
Cisplatin (CAS no 15663-27-1, MF-Cl2H6N2Pt; NCF-119875), cisplatinum, also called diamminedichloroplatinum (II), is a metallic (platinum) coordination compound with a square planar geometry Cisplatin was first synthesized by M Peyrone in 1844 and its chemical structure was first elucidated
cis-by Alfred Werner in 1893 However, the compound did not gain scientific investigations until the 1960s when the initial observations of Rosenberg et al (1965) at Michigan State University pointed out that certain electrolysis products of platinum mesh electrodes were capable of inhibiting cell division in Escherichia coli created much interest in the possible use of these products in cancer chemotherapy Cisplatin has been especially interesting since it has shown anticancer activity in a variety of tumors including cancers of the ovaries, testes, and solid tumors of the head and neck It was discovered to have cytotoxic properties in the 1960s, and by the end of the 1970s it had earned a place as the key ingredient in the systemic treatment of germ cell cancers Among many chemotherapy drugs that are widely used for cancer, cisplatin is one of the most compelling ones It was the first FDA-approved platinum compound for cancer treatment in 1978 This has led to interest in platinum (II)—and other metal—containing compounds as potential anticancer drugs
CHAPTER 2 Materials and Methods 2.1 Materials
Chemical agents were purchased from Acros, Sigma Aldrich, Merck with high purity, suitable for synthetic organic chemistry and for analytical specifications
Equipment: desiccator, sonication, magnetic Stirrer and hot plate, vacuum oven, vacuum rotary evaporator Eyala, water bath memmert, freeze dryer at German Vietnamese Technology Center, Ho Chi Minh City University of Food Industry Morphology and size of dried particles was taken by TEM at 140kV (JEOL JEM 140, Japan) Fourier-transform infrared spectroscopy (FTIR) was analysed by Equinox 55 Bruker HPLC was done by Agilent 1260 (USA) 1H-NMR spectrum was obtained from Bruker Avance 500 Amount of Pt was determined using ICP-MS-7700x/Agilent (VILAS) The cytotoxic assay was investigated following the help of Molecular Lab, Genetics Department, University of Science, HCM
2.2 Methods
2.2.1 Synthesis of PAMAM dendrimer of generation G4.5 from the ethylenediamine (EDA) core
Trang 6The synthetic route of PAMAM dendrimer of generation G4.5 was employed 11 steps (figure 2.1), starting from the reaction between ethylenediamine (EDA) and methyl acrylate (MA) to form G-0.5 to which the next generation G0, G0.5, G1.0, G1.5, G2.0, G2.5, G3.0, G3.5, G4.0 và G4.5 were expanded The chemical structure and the molecular mass of the obtained products were identified by 1H-NMR
Figure 2.1 Synthetic route of PAMAM dendrimer 2.2.2 Synthesis of PAMAM dendrimer G3.0, G4.0 conjugated Cisplatin
Cisplatin was dissolved in water and stirred at room temperature under N2 inviroment The solution of PAMAM dendrimer G3.0, G4.0 in water was adjusted pH to 7-8 using HCl PAMAM dendrimer solution was drop-wised into prepared cisplatin solution and stirred for 24h following 1 h with sonication at room temperature under N2 gas The unbound cisplatin was removed via dialysis The obtained product was then freeze dried to get powder
2.2.3 Synthesis PAMAM dendrimer G2.5, G3,5, G 4.5 conjugated cisplatin
PAMAM dendrimer G2.5, G3.5, G4.5 were hydrolyzed by NaOH to form carboxylated groups COO-
on the surface and were then used to perform the complex compound with cisplatin as section 2.2.2
2.2.4 Synthesis PAMAM dendrimer G2.5, G3,5, G 4.5 conjugated aqueous cisplatin
Hydrolyzed cisplatin was prepared using AgNO3 to withdraw the choloride ion on cisplatin leading to the formation of monoaqua [cis-(NH2)2PtCl(H2O)] and diaqua [cis-(NH2)2Pt(H2O)2] The reaction was taken place at room temperature, under N2 and continuous stirring The hydrolyzed PAMAM dendrimer G2.5, G3.5, G4.5 by NaOH was drop-wised into aqueous cisplatin, stirring for 24h following the sonication in 1 hours under N2 at room temperature The obtained product was then freeze dried to get powder
2.2.5 Modification of PAMAM dendrimer G 3.0 with Poly(N-isopropylacrylamide) (PNIPAM) Carboxylated (-COOH) terminated PNIPAM was activated by pnitrophenyl chloroformate (NPC) and N-Hydroxysuccinimide (NHS) following the reaction with NH2 groups on the surface of PAMAM
Trang 7The remained amino groups (-NH2) on PAMAM dendrimer G3.0- PNIPAM were reacted with methyl acrylate in 96h under N2 condition to form PAMAM dendrimer G 3.5-PNIPAM The chemical structure and grafting degree were estimated by 1H-NMR
2.2.7 Synthesis of the complex PAMAM dendrimer G3.5-PNIPAM and Cisplatin
The complexation reaction between PAMAM dendrimer G3.5-PNIPAM and cisplatin was similar to the description in section 2.2.4
2.2.8 Modification of PAMAM dendrimer G3.0, G4.0 with poly (acrylic acid) (PAA)
PAA was activated using 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) before reacting with NH2-terminal surface function groups of PAMAM dendrimer G3.0, G4.0 The obtained products were purified by dialysis membrane and then free-dried to get powder The chemical structure and grafting degree were estimated by 1H-NMR
2.2.9 Synthesis the complex PAMAM dendrimer G3.0-PAA, PAMAM dendrimer G4.0-PAA and cisplatin
The complexation reaction between PAMAM dendrimer G3.0-PAA, PAMAM dendrimer G4.0-PAA and cisplatin was similar to the description in section 2.2.4
2.2.10 Evaluation the encapsulation and release of 5FU from the complex PAMAM dendrimer G3.5-PNIPAM-Cisplatin
5-FU was dissolved into deionized water (DI) and then drop-wised into PAMAM dendrimer PNIPAM-Cisplatin solution Sonication was applied for 1 h and then the reaction was under regular stirred for 24h at room temperature The obtained products were purified by dialysis membrane and then free-dried to get powder The encapsulation efficacy and the amount of 5-FU release from carrier were analysized by HPLC 2.2.11 Determine amount of cisplatin in products using ICP-MS
G3.5-ICP was performed with G3.5-ICP-MS-7700x/Agilent Amount of Pt was calculated based on Pt 195 and Lutetium 175 as internal standard
2.2.12 Evaluation of in vitro drug release
In vitro release study was investigated with 2 type buffer (pH 7,4 and pH 5,5) as the function of time 2.2.13 Kinetic and pharmacokinetic drug release
The first screening the selection of release kinetic model for cisplatin was come from the common models such as zero-order, first-order, Higuchi, Kormeyer-Peppas and Hixson-Crowell The right model for kinetic release was based on the AIC criteria (Akaike information criterion) and R2
ajust (Adjusted R2), calculating by R program
From the in vitro release and their kinetic model, the pharmacokinetic parameters for cisplatin from nanocarriers were identified
Trang 8The chemical shift of specific proton signals on dendrimer PAMAM were recored in various previous reports The resultant 1H –NMR spectrum showcased the typical protron siginals of dendrimer structure such as: -CH2CH2N< (a) at δH = 2.60 ppm; -CH2CH2CO- (b) at δH = 2.80-2.90 ppm; -CH2CH2CONH- (c) at δH
= 2.30 - 2.40 ppm; -CH2CH2NH2 (d) at δH = 2.70 -2.80 ppm; -CONHCH2CH2N- (e) at δH = 3.20 - 3.40 ppm; -CH2CH2COOCH3- (g) at δH = 2.40 - 2.50 ppm and -COOCH3 (h) at δH = 3.70 ppm
The 1H-NMR spectrum of various dendrimer PAMAM generation was presented below:
1H-NMR PAMAM G-0.5: at δH = 2.47 - 2.50 ppm (a), δH = 2.77-2.80 ppm (b), δH = 2.54 ppm (g) and δH = 3,68 ppm (h)
1H -NMR PAMAM G0.0: at δH = 2.56 - 2.57 ppm (a), δH = 2.77 - 2.82 ppm (b), δH = 2.37 - 2.40 ppm (c), δH = 2.71 -2.75 ppm (d) and δH = 3.25 - 3.27 ppm (e)
1H -NMR PAMAM G0.5: at δH = 2.54 -2.57 ppm (a), δH = 2.76 - 2.82 ppm (b), δH = 2.37 - 2.40 ppm (c), δH = 3.24 - 3.26 ppm (e), δH = 2.45 - 2.48 ppm (g) and δH = 3.66 ppm (h)
1H -NMR PAMAM G1.0: at δH = 2.59 - 2.60 ppm (a), δH = 2.80 -2.82 ppm (b), δH = 2.38 - 2.40 ppm (c), δH = 2.73 - 2.76 ppm (d) and δH = 3.26 - 3.28 ppm (e)
1H -NMR PAMAM G1.5: at δH = 2.58 - 2.59 ppm (a), δH = 2.78 - 2.86 ppm (b), δH = 2.39 - 2.42 ppm (c), δH = 3.27 - 3.29 ppm (e), δH = 2.47 -2.50 ppm (g) and δH = 3.69 ppm (h)
1H -NMR PAMAM G2.0: at δH = 2.57 - 2.59 ppm (a), δH = 2.77 -2.81 ppm (b), δH = 2.36 -2.38 ppm (c), δH = 2.68 -2.74 ppm (d) and δH = 3.24 - 3.27 ppm (e)
1H -NMR PAMAM G2.5: at δH = 2.57 - 2.64 ppm (a), δH = 2.84 - 2.86 ppm (b), δH = 2.40 -2.42 ppm (c), δH = 3.27 -3.30 ppm (e), δH = 2.48 - 2.46 ppm (g) and δH = 3.68 - 3.69 ppm (h)
1H -NMR PAMAM G3.0: at δH = 2.61 - 2.62 ppm (a), δH = 2.80 -2.83 ppm (b), δH = 2.38 - 2.40 ppm (c), δH = 2.74 - 2.76 ppm (d) and δH = 3.26 -3.29 ppm (e)
1H -NMR PAMAM G3.5: at δH = 2.57 -2.64 ppm (a), δH = 2.84-2.85 ppm (b), δH = 2.38 -2.43 ppm (c), δH = 3.27 -3.37 ppm (e), δH = 2.48 -2.51 ppm (g) and δH = 3.69 ppm (h)
1H -NMR PAMAM G4.0: at δH = 2.59 -2.62 ppm (a), δH = 2.80 -2.83 ppm (b), δH = 2.39 – 2.40 ppm (c), δH = 2.74 – 2.76 ppm (d) and δH = 3.26 -3.28 ppm (e)
1H -NMR PAMAM G4.5: at δH = 2.57 - 2.65 ppm (a), δH = 2.84 – 2.85 ppm (b), δH = 2.39 – 2.42 ppm (c), δH = 3.27 - 3.31 ppm (e), δH = 2.47 - 2.50 ppm (g) and δH = 3.69 ppm (h)
Trang 9Figure 3.1 1H-NMR spectrum of various PAMAM Dendrimer generation Thoughout the integral ratios of 2 peaks of protons at (a) and (e) on the 1H-NMR of dendrimer molecules (χNMR) and the intergal ratio of the number of the protons at (a) and (e) in the theorical dendrimer structure (χL.T), the molecular weight of dendrimers can be established following the below equation:
∑H(-CH
2 -) (a)
.MLT
In which:
SH(-CH (e)2-), SH(-CH (a)2-) : the peak areas of protons
at (a) and (e) in 1H-NMR
∑H(-CH (e)2-), ∑ H(-CH (a)2-): the sums of protons at the (e) and (a) position s in the molecular formula of PAMAM dendrimer
MLT : the theoretical molecular weight of PAMAM dendrimer
The results were calculated according to:
Table 3.1 Calculated molecular mass of Dendrimer following 1H-NMR
H(-CH (e)2-) H(-CH (a)2-) χLT M(LT) χNMR M(NMR) Different
(%)
Trang 103.2 FT-IR spectrum of the complex PAMAM dendrimer and cisplatin
3.2.1 FTIR PAMAM dendrimer G2.5, G3.5, G4.5 and complex G2.5-CisPt, G3.5-CisPt, CisPt
G4.5-Both FT-IR spectrum of PAMAM G2.5, G3.5 contain strong absorption peak (νC=O) and moderate absorption peak (νC-O) at 1731 cm-1, 1045 cm-1 (G2.5); 1736 cm-1, 1646 cm-1 (G3.5), respectively, corresponding to the vibiration of ester functional group A broad band with strong viberation corresponds to the stretching –OH groups at 3294 cm-1 (G2.5); 3302 cm-1 (G3.5); 3426 cm-1 (G4.5), which hinder the viberation of amide bonding FT-IR also presents the assymetric stretching –CH2, CH3, –CH3 at 2952 cm-1,
2832 cm-1 (G2.5); 2952 cm-1, 2830 cm-1 (G3.5) and out-of-plane stretching CH3 at 1360 cm-1 (G2.5), 1359
cm-1 (G3.5), 1399 cm-1 (G4.5) The vibrational modes of the obtained FT-IR of various PAMAM dendrimer generation were similar to PAMAM dendrimer G2.5, 3.5, 4.5
The FT-IR spectrum of all complex PAMAM G2.5-Cisplatin, G3.5-Cisplatin, G4.5-Cisplatin also have similar signal as compared to PAMAM G2.5, 3.5, 4.5 However, the absorption of these peaks are quite difference Due to the formation of complex, the ester functional groups at the surface of PAMAM are converted to COO- leading to the intensity of viberation of ester groups (νC=O, νC-O) are reduced Also, due to the overlap of asymmetrical/symetrical stretching of COO- on viberation of amide band I, amide band II and vibration of aliphatic CH3, the intensity of these peaks are increased, confirming the presentation of the viberation of N-H bonding in cisplatin Together, the change in the intensity of these peaks provide the evidence for the formation of coordinative bond between Pt2+ and carboxylate -COO- groups on the surface of PAMAM dendrimer
Trang 113.2.2 FT-IR spectrum of complex PAMAM Dendrimer G3.0-Cisplatin, G4.0-Cisplatin
Figure 3.2 FT-IR spectrum of PAMAM dendrimer G2.5, G3.5, G4.5 and complex G2.5-Cisplatin, Cisplatin, G4.5-Cisplatin
G3.5-FT-IR of PAMAM dendrimer G3.0 and G3.0-Cisplatin; G4.0 and G4.0-Cisplatin showcased the spectra shifting for –NH viberation at 1643 cm-1 to 1639 cm-1 (G3.0, G3.0-Cisplatin); 1643 cm-1 to 1642 cm-1(G4.0, G4.0-Cisplatin) This sugguests the formation of the coordinative bond between cation Pt2+ and NH2groups on the surface of PAMAM dendrimer G3.0 Furthermore, the reduction of intensity and the shifting of symmetric/ asymmetric vibration of aliphatic -CH2 at 2944 cm-1 and 2839 cm-1 in FT-IR spectrum of PAMAM dendrimer G3.0 to 2975 cm-1 and 2884 cm-1 in the complex G3.0-Cisplatin along with the aborption peaks at
3437 cm-1 (G3.0-Cisplatin) and 3427 cm-1 (G4.0-Cisplatin) corresponding to the N-H viberation on the cisplatin spectrum
3.3 FT-IR spectrum of the complex G3.0-PAA and Cisplatin
Trang 12Figure 3.3 FT-IR spectrum of PAMAM dendrimer G3.0, G4.0 and the complexc G3.0-Cisplatin, G4.0-Cisplatin
FT-IR spectrum exhibits the slight shifting of asymmetric –COO viberation and amide peak -NH in G3.0-PAA at 1644 cm-1 and 1571 cm-1 to 1642 cm-1 and 1565 cm-1 in case of G3.0-PAA-Cisplatin These peaks with weak intensity assigning to the stretching and bending of -CH2 and CH-CO in G3.0-PAA are at
1454 cm-1 and 1409 cm-1, which are shifting to 1453 cm-1 và 1406 cm-1 in term of G3.0-PAA-Cisplatin The sharp peak at 3435 cm-1 regarding to the stretching N-H group in cisplatin This behavior proposes the interaction of cation Pt2+ and -COO- on the surface of G3.0-PAA
Trang 133.4 FT-IR spectrum of complex G4.0-PAA-Cisplatin
Figure 3.5 FT-IR spectrum of G4.0-PAA and complex G4.0-PAA-Cisplatin FT-IR spectrum exhibits the slight shifting of asymmetric –COO viberation and the overlap of amide peak -NH in G3.0-PAA at 1572 cm-1 cm-1 to 1564 cm-1 and 1635 cm-1 in respected to G4.0-PAA-Cisplatin The weak intensity peaks contributing the stretching and viberation of -CH2 and CH-CO for G4.0-PAA at 1454
cm-1 and 1407 cm-1 are shifted to 1447 cm-1 và 1400 cm-1, respectively, in case of G4.0-PAA-Cisplatin A viberation at 3619 cm-1 is assigned to the stretching –OH of –COOH on 0-PAA This phenomina proposes the interaction of cation Pt2+ and -COO- on the surface of G4.0-PAA
3.5 1H-NMR result of PAMAM G3.0 and G 3.5 modififed with PNIPAM
As shown in the 1H-NMR spectrum of G3-PNIPAM (mole ratio 1:8), beside the typical proton peak for PAMAM G3.0, some the proton signals are originated from PNIPAM-COOH such as –CH3 (f) at 1,10-1,26 ppm, -(CH3)2CHNH- (l) at 3,99 ppm In addition, the proton of –CH2CH2CONH (c) shifts from 2.0 to 2.68 ppm, confirming the formation of linkage between NH2 of PAMAM G3.0 and–COOH of PNIPAM-COOH This results show the successful of synthesis nanocarrier based thermal responsive dendrimer
Figure 3.4 FTIR spectrum of G3.0-PAA and complex G3.0-PAA-Cisplatin
Trang 14Figure 3.6 1H-NMR spectrum of nanocarrier based on G3.0-PNIPAM (mol ratio 1:8)
From 1H-NMR spectrum of G3-PNIPAM, the grafting degree as well as the number PNIPAM-COOH conjugated on PAMAM G3.0 following the below formula:
Table 3.2 The numer PNIPAM groups conjugating on G3.0 and their estimated molecular weight
weight based
on1H-NMR
transition temperature
For G3.5-PNIPAM, beside the typical proton signals of
PNIPAM-COOH, other proton signals originating from
PAMAM dendrimer generation 3.5 such as –COOCH3 (h)
(3,73-3,78 ppm); –CONHCH2CH2N- (e) (3,26-3,36 ppm); –CH2CH2N
(a) (2,57-2,63 ppm) are also exhibited on the 1H-NMR spectrum
of G3.5-PNIPAM This results provide the evidence for the
linakage between –COOCH3 and amine groups on the surface of
Trang 15A long with the typical proton signals for PAMAM dendrimer G3.0 such as peak –CH2CH2N (a) (2.63ppm), peak –CONHCH2CH2N- (e) (3.30 ppm), the characterized peak for acid polyacrylic, including
>CHCOOH (b) (2.07 ppm) >CHCH2CH< (c) (1.61 ppm) exposes in the 1H-NMR spectrum of PAA modified PAMAM G3.0 (G3.0-PAA) This revels the formation of the linkage -CO-NH between -NH2 groups on the surface of PAMAM dendrimer G3.0 and –COOH on PAA chains This observation can help to confirm the success of the G3.0-PAA synthesis process Regarding 1H-NMR spectrum of G3.0-PAA, the number PAA groups attacked PAMAM dendrimer G3.0 is 6,01 (yield: 50,1%) When mol rate PAMAM dendrimer G3.0: PAA was 1:6, the number PAA groups conjugated on the PAMAM dendrimer G3.0 is 5 (yield: 83,3%)
3.7 1H-NMR spectrum of PAA modified PAMAM G4.0
In the same maner to G3.0-PAA, the 1H-NMR spectrum reveals the successful synthesis of carrier based on G4.0-PAA From the 1H-NMR spectrum of G4.0-PAA, the number of PAA attached on PAMAM dendrimer G4.0 is 15.16 (yield: 94.7%) With mole ratios PAMAM dendrimer G4.0: PAA is 1:8, the number PAA conjugating on the surface of PAMAM dendrimer G4.0 is 7.28 (yield: 91.0%) Further increase the mol
of PAA in the ratio upto 1:24; however, the reaction was unscessfull (the solidification in reaction bath)
3.8 Amount of Pt from complexes
3.8.1 Amount of Pt from complex full
generation PAMAM dendrimer -cisplatin
Figure 3.9 1H-NMR spectrum of PAA modified
PAMAM dendrimer G3.0 (mol ratio 1:12)
Figure 3.10 1H-NMR spectrum of PAA modified PAMAM dendrimer G 4.0 (mole ratio 1:16) Figure 3.8 1H-NMR spectrum of G3.5-PNIPAM