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Amphiphilic conetwork gel membranes based on biocompatible polymers and their applications
CSIR-CSMCRI
CSIR-SRF (GATE) Assessment Presentation
Arvind Kumar Singh Chandel Enrolment no: 10BB14J16016
Under the guidance of
Reverse Osmosis (Membrane) Division CSIR- Central Salt & Marine Chemicals Research Institute
Bhavnagar, Gujarat-364002
Dr. Suresh K. JewrajkaCo-supervisior
Dr. Soumya Haldar
Objective The main objective of this work is the synthesis of biocompatible biodegradable amphiphilic conetwork gel membranes for biomedical applications.The objectives of the thesis work may subdivided as follows: Synthesis and functionalization biocompatible/biodegradable
(co)polymers. Chemical reaction of copolymers and cross-linker to obtain gel
membranes. Combining premade polysaccharide with functional hydrophobic
polycaprolactone-based copolymers to obtained amphiphilic gel membrane with desirable characters for drug delivery and tissue engineering applications. Synthesis and functionalization ofhydrophilic and hydrophobic polymers/copolymers
Cross-linking Amphiphilic gel membranes
Biomedical applications
IntroductionGel materials Chemically or physically cross-linked soft insoluble materials those swell in solvents.
Gel
Hydrogel Amphiphilic conetwork gel
Formed by combination of purely hydrophilic polymersEg. Starch gel, agarose gel, PEG gel
Formed by combination of hydrophilic and hydrophobicpolymers and forms co-continuous morphologye.g. PEG/PCL gel PMMA/PDMA gel
Adv. Drug Delivery Rev.2002, 54, 135–147..Curr.Med.Chem. 2013;20(1):79-94.
HC
H2C p
Cl
HC CH2
Cl
AIBN
(B)
Polycaprolactone diolCl
ClO
OOOO
OH
O
HOn n
Et3N/ 24 hroom temperature
OOO
OO
OO
OO
Cl
OO
O
Cl
On n
(C)
ClCH2-Ph-PCL-Ph-CH2ClO O
OO OH
OOOH
O
CH2
CH3C COOCH3
HO
CH2
C CH3CO
OCH2
CH2
NMe2
O OO
O OHOO
OH
OHHO
Agr
iBuBr/Et3N
O OO
O OHOO
OH
O
COCH3C CH3
Br
HO
OOO
OHOO O
HO
O
H2CC CH3H3COOC
OH
H2CCH3C C
O
OCH2
CH2
NMe2
MMA+DMA/CuBr+bpy
(2) DMA/CuBr+bpy(1) MMA/CuBr+bpy
Agr-I
(A)
Agr-g-PMMA-b-PDMA Agr-g-PMMA-co-PDMA
Amphiphilic gel (APG) of graft copolymer of agarose (Agr) and polycaprolactone (PCL) or polychloromethyl styrene (PCMSt)
Synthesis of precursors
Scheme 1. Synthesis of precursors
O OO
O OHOO
OH
O
CH2
CH3C COOCH3
CH2
CH3C
HOO O
OO OH
OOH
O
CH2
CH3C COOCH3
CH2
CH3C CO
OCH2
CH2
Me2N
HOO O
OO OH
OOH
O
CH2
CH3C COOCH3
CH2
CH3C
HO
m m m
H2CC CH3C
O
OCH2CH2
Me2N
n
CH2
C CH3CO
OCH2CH2
Me2N
n
CH2
C CH3CO
OCH2CH2
Me2N
n
CO
OCH2
CH2
Me2N
CO
OCH2
CH2
Me2N
HC
HC
H2C
HC
H2C
HC
H2C
HC C
H2HC
H2C
HC
H2C
HC
H2C
HC
H2C
HC C
H2
H2C
Anotherpolymerchain
Styrenic backbone
Agr-g-PMMA-b-PDMA
70 OC
HC
H2C p
Cl
O OO
O OH OOOH
OCOCH3C CH3
CH2
CH3C COOCH3
CH2
CH3C
HOO O
OO OH O
OH
OCOCH3C CH3
CH2
CH3C COOCH3
CH2
CH3C CO
OCH2
CH2
Me2N
HOO O
OO OH O
OH
OCOCH3C CH3
CH2
CH3C COOCH3
CH2
CH3C
HOm m m
H2CC CH3C
O
OCH2
H2CMe2N
n
H2CC CH3C
O
OCH2CH2NMe2
n
CH2
C CH3CO
OCH2
H2CNMe2
n
CO
O
CH2
H2CNMe2
CO
OCH2
CH2
Me2N
OOOO
OO
OOO
Cl
OO
O
Cl
On n
OOOO
OO
OO
O OO
OOOOO
OO
OO
OO O
OOO
n n
nn
PCL backbone
PCLbackbone
70 OC
Agr-g-PMMA-b-PDMA
Amphiphilic gel of graft copolymer of Agr and PCL or PCMSt
Amphiphilic gel of Agr-g-PMMA-b-PDMA and PCL-Cl
Synthesis of Amphiphilic gel
Amphiphilic gel of Agr-g-PMMA-b-PDMA and PCMSt
Scheme 2.
Injectibility of APG particles
Agr-NMe2
+Cl-PCL-b-PEG-b-PCL-Cl
YY
Gel particles of size ~160 m was obtained by mechanical milling of liquid nitrogen frozen APG films and filtering the particles through 160 mesh sieves. The particles remain dispersed in water for about 10 min and are injectable through hypodermic syringe of needle size 20-G.
Mechanical milling
APGMembrane
Scheme 1. Injectibility of APG particles
Characterizations of precursors
Copolymer Agr/PMMA/PDMAz
(wt %)
PDI
APCN gel
PDMA14.5-b-PMMA11-b-PDMA14.5-1
0/31/69 1.3 xAPCNtriblock-1a
PDMA14.5-b-PMMA11-b-PDMA14.5-1
0/31/69 1.81 yAPCNtriblock-1b
Agr115-g-PMMA47-b-PDMA56.2-1
60/20/20
1.73 xAPCNgraft-1
Agr115-g-PMMA40.4-co-PDMA58.8-2
32/68 1.62 xAPCNgraft-2
Agr115-g-PMMA31.2-b-PDMA54.5-3
59/15/26
1.68 xAPCNgraft-3a
Agr115-g-PMMA31.2-b-PDMA54.5-3
59/15/26
1.7 yAPCNgraft-3b
Table 1. x-PCMSt and y-ClCH2Ph-PCL-PhCH2Cl; APCN gels synthesized by reacting copolymers and PCMSt (copolymer:PCMSt=95:5, w/w) or ClCH2Ph-PCL-PhCH2Cl (copolymer:ClCH2Ph-PCL-PhCH2Cl=68:32, w/w); z-gravimetric analysis; subscript indicates Mnx10-3
of total grafting chains of PMMA or PDMA determined from 1H NMR while the Mn of Agr was obtained from GPC and viscosity measurements.
Fig.1: GPC traces of (a) Agr-I and (b) Agr-g-PMMA-b-PDMA-3. GPC was carried out by using DMF as eluent at flow rate 0.8 mL/min
MV
-100.00
0.00
100.00
200.00
300.00
400.00
500.00
600.00
700.00
800.00
900.00
1000.00
1100.00
Minutes0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 30.00
Fig 3: GPC trace of
Fig 2: GPC trace of PMMA and PDMA-b-PMMA
APCN APG Composition(wt %)
E (%) Swelling (%)
Water(Sw)
Toluene(St)
Agr PDMA PMMA PCMSt/PCL
APCNtriblock-1a 0 65 29 6/0 7.1 (±1) 61 (±3) 58 (±3)
APCNtriblock-1b 0 45 20 0/35 9.7 (±2) 19 (±3) 185 (±6)
APCNgraft-1 56 19 19 6/0 6.4 (±1) 49 (±2) 34 (±4)
APCNgraft-2 30 37 27 6/0 7.3 (±2) 42 (±1) 46 (±3)
APCNgraft-3a 56 25 13 6/0 7.2 (±2) 128 (±2) 35 (±3)
APCNgraft-3b 38 17 10 0/35 8.5 (±1) 102 (±3) 112 (±4)
Characterizations of APG membranes
Composition, extractable (E) and equilibrium swelling of APG membranes
Table 2: Composition, extractable (E) and equilibrium swelling of APG membranes
FD
ECA
B
G
H
I K
J L
Fig. 4: Digital pictures of (A) dry, (B) water wet, (C) dry RB adsorbed, (D) water wet RB adsorbed, (E) dry riboflavin adsorbed and (F) water wet riboflavin adsorbed APCNgraft-3a showing transparency.
Nanophase separated co-continuous structure
200 nm
D
200 nm
C
A
200 nm 200 nm
B
Fig.5:Phase mode AFM images of representative APCN gels. Images A-D are for APCNtriblock-1a, APCNtriblock-1b, APCNgraft-3a, and
APCNgraft-3b respectively. The thin film was deposited on mica surface for AFM analysis.
20 30 40 50 60 70 80 90 100 110 120 130
c'
c
b
a'
aHea
t flo
w (e
ndo)
Temparature (oC)
GraftPCL TriblockPCL tria graft1 graft3a
Fig. 6. DSC thermograms: (a) APCNtriblock-1a, (a') APCNtriblock-1b (b) APCNgraft-1, (c) APCNgraft-3a and (c') APCNgraft-3b. Tgs of PMMA (Tg= ca. 100 oC) and PDMA (Tg= ca. 35 oC).38 On the other hand, APCNgraft-3b and APCNtriblock-1b show single Tg at ca. 68 oC due to mixed PDMA/PMMA part. This indicates relatively high degree of phase miscibility in PCL containing APCNs.
Thermal phase analysis of APG membranes
DSC thermograms: (a) APCNtriblock-1a, (a') APCNtriblock-1b (b) APCNgraft-1, (c) APCNgraft-3a and (c') APCNgraft-3b.
Tgs of PMMA (Tg= ca. 100 oC) and PDMA (Tg= ca. 35 oC).38 On the other hand, APCNgraft-3b and APCNtriblock-1b show single Tg at ca. 68 oC due to mixed PDMA/PMMA part. This indicates relatively high degree of phase miscibility in the PCL containing APCNs.
Tensile stress-strain property of APCN membranes
0 10 20 30 40 50 60 70 80 900
1
2
3
4
5
6
7
c'
ca
a'
co15 co41 triblock PCLgraftco Grfattri
b
Tens
ile st
ress (M
Pa)
Strain (%)
Fig. 7. Stress-strain profiles of (a) APCNtriblock-1a, (a') APCNtriblock-1b (b)
APCNgraft1, (c) APCNgraft-3a and (c') APCNgraft-3b. Stress-strain measurements (up to failure) were performed with the water swelled films.
The tensile stress-strain behavior of APCNs was significantly influenced by their degree of water swelling
The tensile stress (at break) follows the order for the APCNs, APCNtriblock-1b> APCNgraft-1>APCNtriblock-1a> APCNgraft3b~APCNgraft3a.
This order of tensile stress is due to enhanced swelling of the network in opposite order.
Degradation of APCN gel membranes
0 10 20 3070
75
80
85
90
95
100
Rem
aini
ng w
eigh
t (%
)
Hydrolytic time (day)
APCNgraft-3a at pH=5 APCNgraft-3b at pH=7.4 APCNgraft-3b at pH=5 APCNgraft-3b at pH=7.5
Characterizations of species formed by degradation of APGs
Fig. 8. Degradation profiles of representative APCNgraft-
3a and APCNgraft-3b at pHs 5 and 7.4.
APCNgraft-3a and APCNgraft-3b
undergo ca. 24% and 21% (w/w) degradations respectively at pH 5 for up to 30 days at 37 oC. The degradation was ca. 12% (w/w) for both the APCNs at pH 7.4
At acidic pH enhanced rate of degradation of Agr backbone of APCN due to hydrolytic cleavage of ester-linkages of reacted DMA moieties
The degraded species were soluble in water and formed foam in the degraded medium owing to their surface active nature
forms micelles with broad particle size distributions having hydrodynamic diameter ~135 nm and 142 nm respectively as confirmed by DLS analyses
pH 7.4 pH 5Fig. 9. foam formation APG membrane degraded species at pH 7.4 and pH 5
Drug Release from the APG membranes
0 20 40 60 80 100 120 140 160 1800
20
40
60
80
Cum
ulat
ive
rele
ase
(%)
Time (h)
pH=5pH=7.4
0 100 200 300 4000
10
20
30
40
50
60
Cum
ulat
ive
rele
ase
(%)
Time (h)
pH 5 pH 7.4 5-fluorouracil
APCNgraft 3a
5-fluorouracilAPCNgraft-3a
0 50 100 150 200 250 300 350 400
20
40
60
Time (h)
Cum
ulat
ive
rele
ase
(%)
A
pH 5 pH 7.4
0 50 100 150 200 250 300 350 4001.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
B
Dru
g re
leas
e (m
g)
Time (h)
pH 5 pH 7.4
Fig. 10. Release of prednisolone acetate at the outside the dialysis tubes from (A) APCNgraft-3a and (B) APCNgraft-3b at pH 5 and 7.4.
Prednisolone acetate APCNgraft-3a
Prednisolone acetate APCNgraft-3b
Fig. 11. Release of 5 Fluorouracil at the outside the dialysis tubes from (A) APCNgraft-3a and (B) APCNgraft-3b at pH 5 and 7.4..
(A) (B)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4 A
Con
trol
Deg
rade
d sp
ecies o
f APC
Ngr
aft-3a
APC
Ntrib
lock
-1b
APC
Ntrib
lock
-1a
APC
Ngr
aft-3
b
APC
Ngr
aft-3a
Sample
Cell v
iabi
lity
B E H K N Q
0
1
2
3
4
5
6
7 B
Sample
Hem
olys
is (%
)
Deg
rade
d sp
ecies o
f APC
Ngr
aft-3
a
APC
Ngr
aft-3
b
APC
Ngr
aft-3
a
APC
Ntr
iblo
ck-1
b
APC
Ntr
iblo
ck-1
a
B E
Cytocompatibility and blood compatibility assay
Fig. 12. Viability of HeLa cells after 24 h of incubation with APCN gels and species formed by degradation of representative APCNgraft-3a at 37 0C
Fig. 13. Hemocompatibility of APCN gels and degraded species of APCNgraft-3a after incubation with blood cells for 1 h at 37 0C
The cytocompatibility of APCN gels and species formed by degradation of representative APCN gels was determined by MTT assay using the HeLa cell line
The MTT assay indicates a high degree of cell viability after treating HeLa cells with various APCN gels. And degraded species of APCN with the polystyrene tissue culture plate (standard) indicates the cytocompatibility.
Hemocompatibility is also an essential criterion of materials for the Biomedical use
Hemolysis of RBCs in presence of various APCN and its degraded species in the presence of triton-X and 0.9% NaCl solution as positive and negative control .
Low hemolysis (5-6%) recorded. Its indicates high degree of hemocompatibility of APCN and its degraded species.
Synthesis of APGs from agarose amine and halide terminated polycaprolactone
O OO
O OHOO
OH
OHHO
Agr
O OO
O OHOO
OH
OHO
(A)
O
NNCH3NN
HCH3
HN
O
NCH3
CH3
H3C N NH2
CH3N N
NN
O
THF/16hroom temperature
DMPUNMP/120h
80 oC
CDIDMPA
Agr-NMe2
O
OH2C
H2C OHOH
OHO
OO
nO
OHO
O
n
O
O m
ClO
Cl
OO OO
OnO
OO
n
O
O mO O
Cl Cl
m
(B)
Et3N/24hroom temperature
1400C 6h
ClCH2Ph-PCL-b-PEG-b-PCL-PhCH2Cl
Sn(II)(Oct)2
O OO
O OHOO
OH
OHO
HN
O
N
CH3
CH3
OO OO
OnO
OO
n
O
O mO O
Cl Cl
(C)
70 OC
OO
N
OO
OnO
OO
n
O
O mO O
O OO
O OHOO
OH
OHO
O
N
CH3
CH3
N
OOO
OHO
OO
HO
OOH
O
N
CH3
H3C
(D)
Synthesis of precursors
Synthesis of Amphiphilic gel
Scheme 4. Synthesis of APGs from agarose amine and halide terminated polycaprolactone
O OOO
OnO
O OO
OmOO
OOO
OHOO
OHO
OOH
ONCH3
H3C
O OO
O OHO
OOH
OHO
O NCH3
CH3
D
Synthesis of APGs from agarose amine and halide terminated polycaprolactone
O OO
O OHOO
OH
OHHO
Agr
O OO
O OHOO
OH
OHO
(A)
O
NNCH3NN
HCH3
HN
O
NCH3
CH3
H3C N NH2
CH3N N
NN
O
THF/16hroom temperature
DMPUNMP/120h
80 oC
CDIDMPA
Agr-NMe2
O
OH2C
H2C OHOH
OHO
OO
nO
OHO
O
n
O
O m
ClO
Cl
OO OO
OnO
OO
n
O
O mO O
Cl Cl
m
(B)
Et3N/24hroom temperature
1400C 6h
ClCH2Ph-PCL-b-PEG-b-PCL-PhCH2Cl
Sn(II)(Oct)2
O OO
O OHOO
OH
OHO
HN
O
N
CH3
CH3
OO OO
OnO
OO
n
O
O mO O
Cl Cl
(C)
70 OC
OO
N
OO
OnO
OO
n
O
O mO O
O OO
O OHOO
OH
OHO
O
N
CH3
CH3
N
OOO
OHO
OO
HO
OOH
O
N
CH3
H3C
(D)
Synthesis of precursors
Synthesis of Amphiphilic gel
Scheme 4. Synthesis of APGs from agarose amine and halide terminated polycaprolactone
O OOO
OnO
O OO
OmOO
OOO
OHOO
OHO
OOH
ONCH3
H3C
O OO
O OHO
OOH
OHO
O NCH3
CH3
D
Characterization of precursors
ab
Fig. 14. GPC traces of (a) starting OH-PEG-OH (Mn=4000 g/mol) and (b) synthesized PCL-b-PEG-b-PCL. GPC was performed using THF as eluent (1 mL/min flow rate). The Mn(GPC) of PCL-b-PEG-b-PCL is 8100 and PDI is 1.28.
1800 1600 1400 1200 1000 800 600
Agr
Wavenumber (cm-1)
1715 cm-1Agr-NMe2
Fig. 15. IR spectra of Agr and Agr-NMe2. The spectrum of Agr-NMe2 showing extra band at 1715 cm-1 due to presence of carbonyl (-C=O) stretching vibration of –O-CO-NH- group.
8 7 6 5 4 3 2 1 0
(ppm)
db e
DMSO-d6
ca
b
Fig. 16. 1H NMR (200 MHz) spectrum of Agr-NMe2 taken in DMSO-d6. The degree of amine substitution in Agr-NMe2 was calculated to be 0.31x.x-The degree of amine substitution in Agr-NMe2 was obtained by calculating molar ratio of -NMe2 to Agr from 1H NMR of Agr-NMe2 as follows: Degree of amine substitution = Ic/2Ia, where Ic is an integral area of the methylene proton (-CH2-CH2-NMe2, 2H, ô=1.87 ppm) of attached amine and Ia is an integral area of the O−CH−O proton (1H, ô=5.2 ppm from glucose units of Agr).
APG Agr/PCL or Agr/PCL-PEG-PCLa
(%, w/w)
Actual amount in APGc
(%, w/w)
Reaction mixture
Actual compositionb
Agr PCL PEG
Agr-PEG-PCL(1:1)
1:1 1:0.55 65 23 12
Agr-PEG-PCL(5:2)
1:0.4 1:0.21 83 11 6
Agr-PCL(1:1) 1:1 1:0.35 74 26 0
Agr-PCL(5:2) 1:0.4 1:0.15 86 14 0
Characterization of amphiphilic gel
Table 3. A-functional polymers and copolymers; b-calculated from two step (acetone and DMF) extraction process and c-from two step extraction and composition of PCL-b-PEG-b-PCL copolymer
DMF Sol fraction and equilibrium swelling of different APG membranes
Conetwork Sol fraction (%)
Swelling (%)
Water Toluene
Agr-PEG-PCL(1:1) 28 (±2) 178 (±6) 22 (±1)
Agr-PEG-PCL(5:2) 18 (±2) 192 (±7) 15 (±2)
Agr-PCL(1:1) 40 (±3) 154 (±5) 36 (±1)
Agr-PCL(5:2) 23 (±3) 163 (±4) 28 (±2)
Agr-PEG (1:1) 10 (±2) 240 (±4) -
Table 4. DMF Sol fraction and equilibrium swelling of different APG membranes
A D
B E
G H
FCJ
I
Fig. 17. Digital pictures of APGs films showing comparative transparency. Pictures: A (dry), B (water swelled) and C (toluene swelled) Agr-PEG-PCL(1:1) films. Pictures D (dry), E (water swelled) and F (toluene swelled) Agr-PCL(1:1) films. Pictures G and H are for RB adsorbed Agr-PEG-PCL(1:1) and Agr-PCL(1:1)
Nanophase separated co-continuous structure
Fig. 18. Images I and J are for phase mode AFM images (5x5 µ) of Agr-PEG-PCL(1:1) and Agr-PCL(1:1) respectively. The thin film was deposited on mica surface for AFM analysis
Phase separation behavior by DSC analysis of APGs
-50 0 50 100 150
(e)
(d)
(c)
(b)
(a)
A
Hea
t flo
w (e
ndo)
40 0
C
82 0
C
74 0
C
Temperature (oC)
Agr-PCL(1:1) Agr-PEG-PCL(1:1) Agr Agr+PCL(1:1) PCL
-70 -68 -66 -64 -62 -60
d
b
a
-690C
B
Fig. 19. Curves a-e are DSC thermograms of Agr-PCL(1:1), Agr-PEG-PCL(1:1), neat Agr, neat PCL and mechanical mixture of Agr+PCL (1:1, w/w) respectively, (B) extended scale DSC thermograms
-50 0 50 100 1500.08
0.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
Agr-PEG-PCL(1:1)
Agr-PEG-PCL(1:1)
B
55 oC
43 oC
Tan
delta
(MPa
)
Temperature (oC)
-50 0 50 100 1500
200400600800
100012001400160018002000220024002600
A-70 oC
-62 oC
65 oC
Agr-PEG-PCL(1:1)
Agr-PCL(1:1)
Stor
age
mod
ulus
(MPa
)
Temperature (o C)
Fig. 20. Storage modulus and tan delta vs. temperature plots of representative Agr- Agr-PCL(1:1) and PEG-PCL(1:1) showing glass transition regions and temperature dependent mechanical property
Thermal phase analysis of APGs
0 20 40 60 80 1000.0
0.2
0.4
0.6
0.8
1.0(a) Agr-PCL (5:2)(b) Agr-PCL (1:1)(c) Agr-PEG-PCL (5:2)(d) Agr-PEG-PCL (1:1)
(a)
(b)
(c)
(d)
Stre
ss (M
Pa)
Strain (%)
Tensile Stress-Strain Property of APG membranes
Fig. 21. Tensile stress-strain properties of APGs in their equilibrium water swelled state.
Higher amount of PCL in the APGs also enhances the stress-strain property of Agr-PEG-PCL(1:1) and Agr-PCL(1:1) by lowering the water swelling compared to corresponding Agr-PEG-PCL(5:2) and Agr-PCL-(5:2) respectively
Phase separation probably helps to transfer of applied stress from water swelled Agr and PEG to semi-crystalline PCL
0 10 20 30 40 50 600
5
10
15
20
25
30 Agr-PCL(1:1), pH=7.4 Agr-PEG-PCL(1:1), pH=7.4 Agr-PCL (1:1), Lipase, pH=7.4 Agr-PEG-PCL (1:1), Lipase, pH=7.4 Agr-PCL (1:1), pH=5 Agr-PEG-PCL (1:1), pH=5
Deg
rada
tion
(%, w
/w)
Time (Day)
Degradation of APGs
Fig. 22. Degradation of Agr-PCL(1:1) and Agr-PEG-PCL(1;1) in presence of 0.007 (M) aqueous NaOH of pH 9, lipase (0.1%, w/v), 7.4 PBS and PBS of pH 5 for up to 60 days at 37 oC.
Catalyzed degradation of representative Agr-PEG-PCL(1:1) and Agr-PCL-(1:1). The rate of degradation enhances in PEG containing APG in both the catalysed process.
The enhanced rate of degradation of PEG containing APGs is attributed to the enhanced water swelling of the APGs which facilitate the diffusion of OH- or lipase to the proper chemical site and thereby catalysed the degradation compared to only PCL containing APGs.
The rate of degradation enhances in presence of lipase than that of NaOH due to more hydrolytic instability of ester bond of PCL in presence of lipase.
a
a'
b
b' c'
c d
d'
0 10 20 30 40 500
5
10
15
20
25
30
35
40 A
Load
ing
capa
sity
(%)
Time (h)
Agr-PEG-PCL(1:1) Agr-PCL(1:1) Agr-PEG-PCL(5:2) Agr-PCL(5:2)
Hydrophilic drug loading APG membrane
5-Fluorouracil
Fig. 23. Digital pictures of unloaded (pictures a, b, c and d) and 5-fluorouracil loaded (a', b', c 'and d') Agr-PCL(5:2), Agr-PEG-PCL(5:2), Agr-PCL(1:1) and Agr-PEG-PCL(1:1) respectively showing relative transparency
Fig. 24. 5-fluorouracil loading capacity of APGs with drug concentration
a b
0 10 20 30 40 500
5
10
15
20
25
30
Load
ing
Cap
asity
( %
, w/w
)
Time (h)
Agr-PEG-PCL(1:1) Agr-PCL(1:1)
Fig. 26. Gemcitabine loading capacity of APGs with drug concentration
Fig. 25. Digital pictures (a and b) of gemcitabine hydrochloride loaded Agr-PCL(1:1) and Agr-PEG-PCL(1:1) respectively
Hydrophobic drug (Prednisolone acetate ) loading capacity
0 10 20 30 40 5005
10152025303540 A
Load
ing
capa
sity
(%)
Time (h)
Agr-PEG-PCL (1:1) Agr-PCL (1:1) Agr-PEG-PCL (5:2) Agr-PCL (5:2)
Prednisolone acetate
Fig. 27. 5-fluorouracil loading capacity of APGs with drug concentration
b
a
The loading of hydrophobic prednisolone acetate is governed by the amount of hydrophobic component and extent of water swelling of APGs.
The prednosolone acetate loading capaity of Agr-PCL(5:2) and Agr-PCL(1:1) is higher than that of corresponding PEG containing APGs due to high degree of solubilization of the drug by PCL rich phase
This is because the amount of PCL in Agr-PCL(5:2) and Agr-PCL(1:1) is higher than that of corresponding PEG containing APGs.
Fig. 28. digital pictures of prednisolone acetate loaded (a) Agr-PCL(1:1) and (B) Agr-PEG-PCL(1:1).
Stability of drugs ( Prednisolone acetate and 5-Fluorouracil) in the APG membrane matrices
The 5-Flu and prednisolone acetate remained stable inside the APGs as confirmed by
UV-Visible and IR analyses.
The drugs loaded films were stored in air at room temperature for six months and
then the released experiments were conducted for UV-visible analysis.
The absorbance maximum of released 5-Fluo (λmax= 266 nm) and prednisolone acetate
(λmax= 247 nm) remained same as that of pure drugs.
The IR spectra of loaded drugs taken after six months of loading, also exhibited
similar spectra
Fig. 29.
0 50 100 150 200 250 300 3500
5
10
15
20
25
30
35B
Cum
mul
ativ
e re
leas
e (%
)
Time (h)
Agr-PCL(5:2), pH 7.4 Agr-PEG-PCL(5:2), pH 7.4
0 50 100 150 200 250 300 3500
10
20
30
4050
60
70 C
Cum
mul
ativ
e re
leas
e (%
, w/w
)
Time (h)
Agr-PCL(1:1) Film, pH 7.4 Agr-PCL(1:1) Powder, PH 7.4 Agr-PCL(1:1), pH 5 Agr-PCL(1:1), Lipase, pH 7.4 Agr-PEG-PCL(1:1) Film, pH 7.4 Agr-PEG-PCL(1:1) Powder, pH 7.4 Agr-PEG-PCL(1:1), pH 5 Agr-PEG-PCL(1:1), Lipase pH 7.4
Controlled release of hydrophilic drugs (5-Fu)
Fig. 30. The cumulative release of 5-fluorouracil with time from Agr-PCL(1:1) and Agr PCL(5:2) and Agr-PEG-PCL(1:1), Agr-PEG-PCL(5:2) in 7.4 pH, 5pH and presence of Lipase enzyme Agr-PEG-PCL(1:1 ) releases 5-Fu is very slow in comparison to Agr-PCL(1:1)
due to the solubilizing effect of PEG PEG enhanced the phase mixing and internal solubilizing of hydrophilic
drug which also restrict the its release in the medium Release of 5-Fu in liase is higher due to degradation of ester linkage of PEG-
PCL
Interaction of PEG with 5-fluorouracil
Fig. 31. UV-Visible spectra of 5-fluorouracil in water and in water containing PEG
respectively. Concentration of 5-fluorouracil
200 250 300 3500.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
max
5-fluorouracil+water
5-fluorouracil+water+PEG solution
Abso
rban
ce
Wavelength (nm)0 2 4 6 8 10
0
20
40
60
80
100
Cum
mul
ativ
e R
elea
se (%
)
Time (h)
Drug in water Drug in PEG solution
100 150 200 250 300-0.7-0.6-0.5-0.4-0.3-0.2-0.10.00.10.20.30.40.50.60.7
Cp= 3.20 J/(g*K)
Cp= 4.247 J/(g*K)
Agr-PEG-PCL(1:1)/5-Flu
Agr-PCL(1:1)/5-Flu
Heat
flow
(mW
/mg)
Temperature (o C)
5-fluorouracil solubilizing effect of PEG
Fig. 32. 5-FU release from water and PEG solution
Fig. 33. DSC of APG with 5-FUFig. 34. Relative transparency of APG membrane in presence of 5-FU
Controlled release of hydrophilic drugs gemcitabine
0 50 100 150 200 250 300
3
6
9
12
15
B
Cum
mul
ativ
e re
leas
e (%
)
Time (h)
Agr-PEG-PCL (5:2) Agr-PCL (5:2)
a b
Fig. 35. Cumulative release of gemcitabine hydrochloride with time (B) from representative Agr-PEG-PCL(1:1) and Agr-PCL(1:1).
Fig. 36. Digital pictures (a and b) of gemcitabine hydrochloride loaded Agr-PCL(1:1) and Agr-PEG-PCL(1:1)respectively
Release rate of gemcitabine is relatively higher from Agr-PEG-PCL(5:2) than Agr-PCL(5:2) due to hydrophilic nature of gemcitabine and Agr-PEG-PCL(5:2) have higher degree of swelling than Agr-PCL(5:2)
0 50 100 150 200 250 300 3500
10
20
30
40
50
60
70C
Cum
mul
ativ
e re
leas
e (%
)
Time (h)
Agr-PCL(1:1), pH 7.4 Agr-PCL(1:1), pH 5 Agr-PCL(1:1), Lipase, pH7.4 Agr-PEG-PCL(1:1), pH 7.4 Agr-PEG-PCL(1:1), pH 5 Agr-PEG-PCL(1:1), Lipase, pH 7.4
0 50 100 150 200 250 3000
5
10
15
20
25
30
35B
Cum
mul
ativ
e re
leas
e (%
)
Time (h)
Agr-PCL(5:2), pH 7.4 Agr-PEG-PCL(5:2), pH 7.4
Controlled release of hydrophobic drug (prednisolone acetate)
Fig. 37. Cumulative release of prednisolone acetate with time from different APGs in PBS of pH 7.4 and in PBS of pH 7.4, 5 and lipase (pH=7.4) respectively
The release rate of prednisolone acetate is less in Agr-PCL(1:1) andAgr-PCL(5:2) than Agr-PEG-PCL(1:1), Agr-PEG-PCL(5:2) due to high degree of solubilization of the drug by PCL rich phase
This is because the amount (14% and 26%) of PCL in Agr-PCL(5:2) and Agr-
PCL(1:1) is higher than that of (11% and 23%) Agr-PEG-PCL(5:2) and Agr-PEG-PCL(1:1)
Drug release kinetics
After the initial burst release from all three types of drugs, the regression coefficient values (R2) obtained from the zero order kinetic model were greater than those from the first order kinetic model
The diffusion exponent (n) values obtained from the Korsmeyer−Peppas Model are between 0.63-0.64 which indicates that non-Fickian diffusion mechanism; i.e., combination of diffusion and erosion of the matrix predominate. The R2 values obtained with Hixson−Crowell Modelare greater than that of Higuchi model.
Korsemeyer, R. W.; Gurny, R.; Doelker, E.; Buri, P.; Peppas, N. A. Int. J. Pharm. 1983, 15, 25−35.Hixson, A. W.; Crowell, J. W. Ind. Eng. Chem. 1931, 23, 923−931.Higuchi, T. J. Pharm. Sci. 1961, 50, 874−875.
Cytocompatibility and blood compatibility assay
Fig. 38. Viability of HeLa cells after 24 h of incubation with APCN gels and species formed by degradation of representative APCNgraft-3a at 37 0C
Fig. 39. Hemocompatibility of APCN gels and degraded species of APCNgraft-3a after incubation with blood cells for 1 h at 37 0C
The cytocompatibility of APCN gels and species formed by degradation of representative APCN gels was determined by MTT assay using the HeLa cell line
The MTT assay indicates a high degree of cell viability after treating HeLa cells with various APCN gels. And degraded species of APCN with the polystyrene tissue culture plate (standard) indicates the cytocompatibility.
Hemocompatibility is also an essential criterion of materials for the Biomedical use
Hemolysis of RBCs in presence of various APCN and its degraded species in the presence of triton-X and 0.9% NaCl solution as positive and negative control .
Low hemolysis (5-6%) recorded. Its indicates high degree of hemocompatibility of APCN and its degraded species.
0
20
40
60
80
100
120
140
160
ACe
llviability (%
)
Agr-PE
G-PCL
(1:1)
Agr-P
EG-PCL(5:2)
Agr-P
CL(1:1)
Agr-PC
L(5:2)
Con
trol
APG
B E
0
1
2
3
4
5
6
7 B
Agr
-PEG
-PC
L(1:
1)
Agr
-PEG
-PC
L(5:
2)
Agr
-PC
L(1:
1)
Agr-
PCL(
5:2)
Hem
olys
is (%
)
APG
Future work plan
1. Synthesis of purely Agr and PCL-based porous APG membranes for tissue culture application.
2. Dextran-based antimicrobial and biocompatible polymers and gel
Publications
Effect of Polyethylene glycol on Properties and Drug Encapsulation-Release Performance of Biodegradable/Cytocompatible Agarose-Polyethylene glycol-Polycaprolactone Amphiphilic Gels Arvind k. Singh Chandel, Chinta Uday Kumar and bSuresh K. Jewrajka*
Communicated for publication
Thank You….
