degradation of an organic overlayer model of a dental composite analyzed by liquid chromatography...
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Degradation of an Organic Overlayer Model of a Dental Composite Degradation of an Organic Overlayer Model of a Dental Composite Analyzed by Liquid Chromatography Mass SpectrometryAnalyzed by Liquid Chromatography Mass Spectrometry
Peter Koin,2 Ayben Kilislioglu,4 Manshui Zhou,1 James L. Drummond,3 and Luke Hanley1,*University of Illinois at Chicago, Departments of 1Chemistry, 2Bioengineering, and 3Restorative Dentistry, m/c 111, Chicago, IL 60607-7061 USA
4Istanbul University, Department of Chemistry, Avcilar 34320, Istanbul, Turkey
Motivation
Goals
Degradation Study Purpose•Dental Composites consist of a polymerizable resin matrix, reinforcing glass filler particles, and a silane coupler.•One of the most used resin monomer of dental composites is Bisphenol A glycerolate dimethacrylate (BisGMA)•Composites undergo property changes due to oral environment•Environment can weaken materials and reduce restoration longevity•Can release compounds into tissues and accumulate•Study materials that can leach out of composite
New System of Analysis•Degradation studies of commercial composites too complex [1]•Monolayer system to understand degradation and erosion [2]
Monolayer System•Dental composites made of resin matrix, glass particle filler, and a silane coupling agent
•Resin matrix: Bisphenol A glycerolate dimethacrylate (BisGMA)•Glass filler: Nanoporous silicon chip•Silane coupling agent: MPS- 3- (trimethoxysilyl) propyl methacrylate
•Glass particles used to reduce overall polymer shrinkage•Silane coupler covalently links resin to glass filler: improves mechanical properties and increases hydrolytic stability due to hydrophobic nature
Dental Composite Model
Experimental Methods
Conclusions
Funded by National Institute of Dental and Craniofacial Research, DE-07979
[1] MS Zhou, JL. Drummond, L Hanley. Dental Materials. 21 (2005) : 145-155. [2] MS. Zhou, CP. Wu, PD. Edirisinghe, JL. Drummond, L. Hanley. Journal of Biomedical Materials Research A. 76 (2006).
Results
•Study degradation of Dental Composite Model after aging in water for 2 weeks•Qualitative analysis to find degradation peaks using MS Fragmenter software and MS-MS analysis
Silicon Wafer(N-Type 100)
24 (wt)% HF/EtOH
20 mA/cm2, 5 min
Nanoporous silicon 31.6% H2O2
50°C, 1hr
Porous SiO2 Surface (Stored in 1N HNO3 Solution)
Porous SiO22 (wt) % MPS/Toluene
60°C, 96hrs
Wash
Toluene
Baking
80°C, 12hrs
MPS-Silanized Substrate
MPS-Silanized Substrate2.0 mg/ml BisGMA/EtOH
Initiator Solution
Cure, UV light
20 min
Polymerized methacryloyl BisGMA Overlayer
Instrumentation•LCMS
–Finnigan Mat LcQ•HPLC
–SpectraSYSTEMS SCM 1000 vacuum membrane degasser–P4000 gradient elution pump–AS 3000 autosampler–UV 2000 dual-wave length detector
Data Analysis SoftwareACD Labs (Toronto, Ont., Canada)
•ACD MS Manager to analyze and process data•ACD MS Fragmenter- Program generates fragments and structures by using standard fragmentation rules
HPLC Conditions•Mobile Phase: Gradient of MeOH/H20•Flow Rate: 0.3 ml/min•Temperature: Room Temperature, 25°C•UV Wavelength: 250 nm•Column: Reverse Phase Water Symmetry C18 3.5 μm, 3.0 mm diameter, 150 mm length•Injection volume: 10 μL
Standards Analysis to find retention timeStandards
•Resin Material: BisGMA•Silane Coupler: MPS- not run because of adverse effect of MPS with columns•Photoinitiator solution: triethanolamine, vinyl pyrrolidinone, and eosin Y•Glass Filler: nanoporous silicon chip, prepared similar to DIOS chips–Possible Degradation Products: bisphenol A, methacrylic acid
Aged Monolayer Samples3 nanoporous silicon chips per sample2 weeks aged in de-ionized waterAlso aged blank nanoporous silicon chip with no BisGMA or methacryloyl layer to determine nanoporous silicon background
4035302520151050Retention Time (min)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Re
lative
In
ten
sity
462
530
620634
645
363
536
610 684
11
.53
5
15
.97
3
18
.56
8
20
.44
3
21
.77
9
23
.74
6
29
.48
4
31
.31
7
33
.19
9
• TIC of Extract from Methacryoyl BisGMA monolayer on nanoporous silicon aged for 2 weeks in DI water.
88080072064056048040032024016080m/z
8
16
24
32
40
48
56
64
72
80
88
96
Re
lativ
e In
ten
sity
(%
)
495513
530
CH3CH3
O
O
O
CH3
O
CH2
O
OH
CH3
OH
CH2
O
NH4+
CH3CH3
O
O
O
CH3
O
CH2
O
OH
CH3
OH
CH2
O
CH3CH3
O
O
O
CH3
O
CH2
O
OH
CH3
CH2
O
•Electrospray ion trap mass spectra of BISGMA from TIC at 16.0 min with a main peak of m/z 530.
600550500450400350300250200150m/z
8
16
24
32
40
48
56
64
72
80
88
96
Re
lativ
e In
ten
sity
(%
)
191 277 323 409427
495
513
530
CH3CH3
O
O
O
CH3
O
CH2
O
OH
CH3
OH
CH2
O
C+
CH3 CH3
O
CH2+
OH
192
C+
CH3CH3
O
O
CH3
OH
CH2
O
277
CH3CH3
O
O
O
CH3
CH3
CH2
O
OH
OH
428
CH3CH3
O
O
O
CH3
O
CH2
O
OH
CH3
CH2
O
494
M+NH4
• MSMS of BisGMA, m/z 530. Spectra shows the M+NH4 peak at m/z 530, M+H peak at m/z 513, M-H20+H at m/z 495, and main degradation products at m/z 191, 277, and 427
Retention Time (min)
m/z Name# of runs
StructureMethod of ID peak
Structure(# of runs)
16.014 +/- 0.546 530 BisGMA 26MS of Standard-
Obvious
20.623 +/- 0.517 634 (BisGMA)” 25 Unknown Structure MS/MS (14)
19.088 +/- 0.477 620 (BisGMA)’ 15 Unknown Structure MS/MS (4)
21.819 +/- 0.526 644 (BisGMA)”’ 12 Unknown Structure MS/MS (8)
11.343 +/- 0.547 462BisGMA-MA
15MS Fragmenter
Software, MSMS (4)
24.115 +/- 0.304 363BisGMA-
2MA5
MS Fragmenter Software
88080072064056048040032024016080m/z
8
16
24
32
40
48
56
64
72
80
88
96
Re
lative
In
ten
sity (
%)
87 161444
488
532
576
620
708
752
796840
Unknown Structure
• Electrospray ion trap mass spectra of (BisGMA)’ Polymer at 18.6 min, which is a BisGMA polymer derivative with a m/z difference of 44 between peaks.
88080072064056048040032024016080m/z
8
16
24
32
40
48
56
64
72
80
88
96
Re
lative
In
ten
sity (
%)
458
502
546
590
634
678
722
766
810
Unknown Structure
•Electrospray ion trap mass spectra of (BisGMA)” Polymer at 20.4 min.
88080072064056048040032024016080m/z
8
16
24
32
40
48
56
64
72
80
88
96
Re
lative
In
ten
sity (
%)
424
468
512
556
600644
669688
732
776
Unknown Structure
•Electrospray ion trap mass spectra of (BisGMA)”’ Polymer at 21.8 min, which is a BisGMA polymer derivative with a m/z difference of 44 between peaks.
88080072064056048040032024016080m/z
8
16
24
32
40
48
56
64
72
80
88
96
Re
lative
In
ten
sity (
%)
150 427445
462
C H 3CH 3
O
O
O HO OH
C H 3
OH
CH 2
O
CH3CH3
O
O
OHO OH
CH3
OH
CH2
O
+H
+H-H2O
Electrospray ion trap mass spectra from TIC at RT= 11.5 min with a main peak at m/z 462 that corresponds to a BisGMA degradation product
88080072064056048040032024016080m/z
8
16
24
32
40
48
56
64
72
80
88
96
Re
lativ
e In
ten
sity
(%
)
363
747
CH3CH3
O
O
CH3CH3
OH
OH
Electrospray ion trap mass spectra of BisGMA degradation product with a m/z 363, at a retention time of 23.8 min.
302826242220181614121086420Retention Time (min)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Re
lative
In
ten
sity
• TIC of Pure BisGMA run through HPLC, no aging.
OH
OH
OH
SiO
O
O
O
O
Si
O
O
O
O
OH
O
OH
O
O
O
OH
OO
OHO
Si
O
O
OH
O
OH
O
O
O
O
O
HO
O O
OH
O
MPS
+
+
SiO2 Surface Methacryloyl overlayer
Bis-GMA
Bis-GMA-methacryloyl overlayer
hv
Eosin Y / TEA / VP
•Unreacted BisGMA strongly adsorbs to surface of nanoporous silicon and slowly leaches out•Aging also causes hydrolysis of ester bonds and causes degradation products of BisGMA to appear•Oligomer peaks with unknown structures also appear after aging
Si
OH
OHOH
O
O
CH3
O
O
CH3
O
OH
CH3
CH3
O O
OH
CH3
CH2
O
CH3CH3
O
O
OHO OH
CH3
OH
CH2
O
CH3CH3
O
O
CH3CH3
OH
OH
BisGMA-methacryloyl monolayer
BisGMA-MAm/z 462
BisGMA-2MAm/z 363
A
B
•Reaction of BisGMA-methacryloyl monolayer in the presence of water. Hydrolysis of ester bonds causes degradation products of BisGMA to appear. Hydrolysis reactions can also occur at black arrows, but do not show up in sample data.
CH3CH3
O
O
O
CH3
O
CH2
O
OH
CH3
OH
CH2
O
530
CH3CH3
O
O
OHO OH
CH3
OH
CH2
O
462
CH3CH3
O
O
CH3CH3
OH
OH363