Performance of PBS-based Copolymer Containing Different Ether Bond and Its Enzymatic Degradation by Molecular Simulation†

doi:10.7503/cjcu20140722

Abstract

Abstract:

Poly(butylene succinate-co-thiodiglycol succinate)[P(BS-co-TDGS)] and poly(butylene succinate-co-diglycol succinate)[P(BS-co-DEGS)] were synthesized by incorporating thioether group and ether oxygen group to the main chain of poly(butylene succinate)(PBS). Their thermal properties and crystallinity were compared by thermography analysis(TG) and X-ray diffraction(XRD). The degradation and their differences were studied in aqueous media with Candida antarctica lipase N435(CALB) as a catalyst. The possible state of aggregation of copolymers and the combination between N435 lipase and substrate were also studied by molecular simulation. The results verify that the crystallinity and thermal stability of P(BS-co-TDGS) decrease. In addition, molecular docking simulation results show that the binding energy of N435 enzyme and diethylene glyol succinic-diethylene glyol(DEGS-DEG) was larger. That is, the docking of substrate P(BS-co-DEGS) containing ester bond such as thiodiglycol succinate with the active site of N435 lipase was more stable.

Key words: Biodegradable material, Copolymerization, Thioether group, Enzymatic degradation, Molecular simulation, Candida antarctica lipase N435, Poly(butylene succinate)

CLC Number:

O631

TrendMD:

ZHANG Min, JING Jingjing, LI Chengtao, WANG Hui, MA Xiaoyan. Performance of PBS-based Copolymer Containing Different Ether Bond and Its Enzymatic Degradation by Molecular Simulation^†[J]. Chem. J. Chinese Universities, 2014, 35(12): 2706.

Figures/Tables 12

Fig.1 Structures of P(BS-co-TDGS) and P(BS-co-DEGS)

Table 1 Composition and relative molecular weight of copolymers

Polymer	n(BS):n(TDGS)	$f A a$	$M n b$	PDI^b	Polymer	n(BS):n(DEGS)	$f A a$	$M n b$	PDI^b
PBS	100:0	0	71200	2.05	PBS-DEGS5	95:5	4.64	64800	1.71
PBS-TDGS5	95:5	5.70	69300	1.98	PBS-DEGS10	90:10	11.55	68700	1.82
PBS-TDGS10	90:10	10.50	65200	1.93	PBS-DEGS15	85:15	14.32	70400	1.67
PBS-TDGS15	85:15	15.45	69200	1.78	PBS-DEGS20	80:20	19.34	73200	1.85
PBS-TDGS20	80:20	21.32	64300	2.09

Table 1 Composition and relative molecular weight of copolymers

Polymer	n(BS):n(TDGS)	$f A a$	$M n b$	PDI^b	Polymer	n(BS):n(DEGS)	$f A a$	$M n b$	PDI^b
PBS	100:0	0	71200	2.05	PBS-DEGS5	95:5	4.64	64800	1.71
PBS-TDGS5	95:5	5.70	69300	1.98	PBS-DEGS10	90:10	11.55	68700	1.82
PBS-TDGS10	90:10	10.50	65200	1.93	PBS-DEGS15	85:15	14.32	70400	1.67
PBS-TDGS15	85:15	15.45	69200	1.78	PBS-DEGS20	80:20	19.34	73200	1.85
PBS-TDGS20	80:20	21.32	64300	2.09

Fig.2 1H NMR spectra of P(BS-co-TDGS)(a) and P(BS-co-DEGS)(b) Peaks a—m and k', l' are corresponding to positions in Fig.1.

Fig.3 XRD patterns of P(BS-co-TDGS)(A) and P(BS-co-DEGS)(B)

Fig.4 Molecular structures of copolymers(carbon atoms of two chains in blue and green) (A) PBS; (B) PBS-TDGS10; (C) PBS-TDGS20; (D) PBS-DEGS10; (E) PBS-DEGS20.

Fig.5 TGA(A) and DTG(B) curves of copolymers a. PBS; b. PBS-DEGS5; c. PBS-DEGS10; d. PBS-DEGS15; e. PBS-DEGS20;b'. PBS-TDGS5; c'. PBS-TDGS10; d'. PBS-TDGS15; e'. PBS-TDGS20.

Table 2 Thermal properties of the synthesized copolymers

Sample	T_d,5%/℃	T_max/℃	T_m/℃	ΔH_m/(J·g^-1)	X_c(%)		T_c/℃
Sample	T_d,5%/℃	T_max/℃	T_m/℃	ΔH_m/(J·g^-1)	DSC	WXRD	T_c/℃
PBS	310.41	310.41	112.00	70.20	62.68	59.34	77.90
PBS-TDGS5	304.62	380.32	110.77	79.86	58.30	54.29	73.90
PBS-TDGS10	309.08	378.89	105.96	67.23	51.03	48.25	66.98
PBS-TDGS15	307.85	376.98	100.48	45.45	40.58	43.34	62.17
PBS-TDGS20	303.17	369.80	98.57	37.70	33.66	38.14	58.88
PBS-DEGS5	316.11	381.28	111.05	58.09	51.87	54.39	75.35
PBS-DEGS10	305.97	378.41	104.33	47.61	42.51	43.54	67.85
PBS-DEGS15	320.16	380.32	103.33	50.32	44.90	46.72	64.53
PBS-DEGS20	319.64	376.88	96.69	40.54	36.60	45.12	56.34

Fig.6 Enzymatic degradation(A) and kinetics curves(B, C) of copolymers (A) a. PBS; b. PBS-TDGS5; c. PBS-TDGS10; d. PBS-TDGS15; e. PBS-TDGS20; f. PBS-DEGS5; g. PBS-DEGS10; h PBS-DEGS15; i. PBS-DEGS20. (B) a. PBS, k=0.345; b. PBS-TDGS5, k=0.370; c. PBS-TDGS10, k=0.446; d. PBS-TDGS15, k=0.940; e. PBS-TDGS20, k=1.373. (C) a. PBS, k=0.345; b. PBS-DEGS5, k=0.454; c. PBS-DEGS10, k=0.581; d. PBS-DEGS15, k=1.394; e. PBS-DEGS20, k=1.395.

Fig.7 SEM images of P(BS-co-TDGS)(A—D) and P(BS-co-DEGS)(E—H) samples after enzymatic degradation for 0, 1, 3 and 5 d, respectively

Table 3 Docking results of TDGS-TDG and DEGS-DEG with the Auto Dock program

Ligand	$E b a$ / (kJ·mol^-1)	$E inter - mol b$ / (kJ·mol^-1)	$E vdw c$ / (kJ·mol^-1)	$E elec d$ / (kJ·mol^-1)	$E total e$ / (kJ·mol^-1)	$E torsional f$ / (kJ·mol^-1)
TDGS-TDG	-13.77	-34.98	-33.97	-1.51	-9.50	21.21
DEGS-DEG	-18.66	-39.83	-39.08	-1.26	-13.85	21.21

Table 3 Docking results of TDGS-TDG and DEGS-DEG with the Auto Dock program

Ligand	$E b a$ / (kJ·mol^-1)	$E inter - mol b$ / (kJ·mol^-1)	$E vdw c$ / (kJ·mol^-1)	$E elec d$ / (kJ·mol^-1)	$E total e$ / (kJ·mol^-1)	$E torsional f$ / (kJ·mol^-1)
TDGS-TDG	-13.77	-34.98	-33.97	-1.51	-9.50	21.21
DEGS-DEG	-18.66	-39.83	-39.08	-1.26	-13.85	21.21

Fig.8 Substrate-enzyme interactions by docking studies of N435-TDGS-TDG(A) and N435-DEGS-DEG(B)

Fig.9 Surface of the top-ranking docked conformation of compounds TDGS(carbon atoms in light blue) and DEGS(light brown) combined with active site of N435 lipase

References 22

[1]	Gigli M., Negroni A., Zanaroli G., Lotti N., Fava F., Munari A., React. Funct. Polym., 2013, 73(5), 764—771
[2]	Jiang T., He F., Zhuo R. X., Polym. Degrad. Stab., 2013, 98(1), 325—330
[3]	Hwang S. Y., Yoo E. S., Im S. S., Polym. J., 2012, 44(12), 1179—1190
[4]	Liu Y. J., Mao L., Chem. J. Chinese Universities, 2013, 34(12), 2903—2910
	(刘跃军, 毛龙. 高等学校化学学报, 2013, 34(12), 2903—2910)
[5]	Zhu Q. Y., He Y. S., Zeng J. B., Huang Q., Wang Y. Z., Mater. Chem. Phys., 2011, 130(3), 943—949
[6]	Zhang S. P., Wang D., Dang Y., Shi S. Q., Gong Y. K., Chem. J. Chinese Universities, 2012, 33(2), 416—420
	(张世平, 王丹,党媛, 史肃青, 宫永宽. 高等学校化学学报, 2012, 33(2), 416—420)
[7]	Frohberga P., Pietzschb M., Ulricha J., Chem. Eng. Res. Des., 2010, 88(9), 1148—1152
[8]	Díaz-Celorio E., Franco L., Rodríguez-Galán A., Eur. Polym. J., 2012, 48(1), 60—73
[9]	Ding M. L., Zhang M., Yang J.M., Qiu J. H., Biodegradation,2012, 23(1), 127—132
[10]	Hwang S. Y., Jin X. Y., Yoo E. S., Im S. S., Polymer,2011, 52(13), 2784—2791
[11]	Zhou X. M., Mater. Sci. Eng, C, 2012, 32(8), 2459—2463
[12]	Soulis S., Triantou D., Weidner S., Falkenhagen J., Simitzis J., Polym. Degrad. Stab., 2012, 97(11), 2091—2103
[13]	Gigli M., Lotti N., Gazzano M., Finelli L., Munari A., React. Funct. Polym., 2012, 72(5), 303—310
[14]	Zhang M., Ding M. L., Zhang T., Yang J. M., Chem. J. Chinese Universities, 2010, 31(3), 612—615
	(张敏, 丁明亮, 张婷, 杨金明. 高等学校化学学报, 2010, 31(3), 612—615)
[15]	Luic M., Sytefanic Z., Ceilinger I., Hodoscek M., Janezic D., Lenac T., Asler L. I., Syepac D., Tomic S., J. Phys. Chem. B, 2008, 112(16), 4876—4883
[16]	Krieger E., Koraimann G., Vriend G., Proteins,2002, 47(3), 393—402
[17]	Krieger E., Darden T., Nabuurs S., Finkelstein A., Proteins,2004, 57(4), 678—683
[18]	Morris G. M., Goodsell D. S., Halliday R. S., Huey R., Hart W. E., Belew R. K., Olson A. J., Autodock, Version 4.0.1, The Scripps Research Institute, La Jolla, CA, USA, 2007
[19]	DeLano W. L., The PyMOL Molecular Graphics System, Revision 0.99, DeLano Scientific, San Carlos, CA, USA, 2002
[20]	Gigli M., Lotti N., Gazzano M., Finelli L. Munari A., Applied Polymer, 2012, 126(2), 686—696
[21]	Lotti N., Siracusa V., Finelli L., Marchese P., Munari A., Eur. Polym. J., 2006, 42(12), 3374—3382
[22]	Díaz A., Franco L., Estrany F., del Valle L. J., Puiggalí J., Polym. Degrad. Stab., 2014, 99, 80—91