Download Synthesis and Characterization of Amphiphilic Antibacterial Cop

Synthesis and Characterization of Amphiphilic Antibacterial
Copolymers
Yongxiao Bai1,*, Yaobin Liu2, Yanfeng Li2, Qi Zhang3
1
Institute of Material Science and Engineering, Key Laboratory for Magnetism and Magnetic
Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, China
2
Department of chemistry and chemical engineering, Lanzhou University, Lanzhou 730000, China
3
School of life science, Lanzhou University, Lanzhou 730000, China
*Corresponding author’s e-mail: [email protected] and Fax: +86 9318913554
Figure S1. Stucture of as-synthesized three kinds of chain transfer agents (CDB,
PEDB and CPDN).
Figure S2. Schematic illustration of the structure of PS-b-PDMA.
Figure S3. FTIR spectrum of PS15-b-PDMA26 (a), PS30-b-PDMA59(b) and
PS21-b-PDMA56 (c). IR (KBr): 2915-2750 cm-1 (N(CH3)3), which confirms
successfully quaternized.
Figure S4. GPC curves of PS-CTA and PS-b-PDMAEMA. Actual line (－) indicates
PS-CTA,
Mn,GPC=13440g/mol,
PDI=1.13;
PS-b-PDMAEMA, Mn,GPC=32448 g/mol, PDI=1.30.
dashed
line
(---)indicates
Figure S5. Cytotoxicity assays of diblock copolymers. The above photograph is
cytotoxicity assay of PS21-b-PDMA56 and the below photograph is cytotoxicity assay
of PS30-b-PDMA21 (1# test-tube contains 2.5 ml 2% of blood, 2.0 ml saline, 0.5 ml 10
mg/ml polymer, 0 ml water; 2# test-tube contains 2.5 ml 2% of blood, 2.1 ml saline,
0.4 ml 10 mg/ml polymer, 0 ml water; 3# test-tube contains 2.5 ml 2% of blood, 2.2
ml saline, 0.3 ml 10 mg/ml polymer, 0 ml water; 4# test-tube contains 2.5 ml 2% of
blood, 2.3 ml saline, 0.2 ml 10 mg/ml polymer, 0 ml water; 5# test-tube contains 2.5
ml 2% of blood, 2.4 ml saline, 0.1 ml 10 mg/ml polymer, 0 ml water; 6 # test-tub
(negative control with unhemolysis) contains 2.5 ml 2% of blood, 2.5 ml saline, 0 ml
10 mg/ml polymer, 0 ml water;7 # test-tube (positive control with hemolysis ) contains
2.5 ml 2% of blood, 0 ml saline, 0 ml 10 mg/ml polymer, 2.5 ml water).
Figure S6. TEM images of PS21-b-PDMA76 (a) and PS11-b-PDMA56(b).
Figure S7. Diagrams of relative lower molecular weight and MIC of S.aureu (a) and
E.coli (b).
Figure S8. Diagrams of relative higher molecular weight and MIC of E.coli (a),
S.aureu (b), M.albican (c).
Figure S9. Schematic presentation of the structural difference of Gram-negative
bacteria (such as E. coli) and Gram-positive bacteria (such as S. aureus).
Gram-negative bacteria have an outer membrane different from Gram-positive
bacteria.
It is well known that the bacterial cell surface is usually negatively charged as
evidenced by its susceptibility to electrophoresis. Adsorption of polycations onto the
negatively charged colloidal surface is expected to take place to a greater extent than
that of monomeric cations. The higher antimicrobial activity of the polymers may be
accounted for by the contribution of the polymers to each elementary process in the
antimicrobial action. For example, the sequence of elementary events in the lethal
action of the cationic biocides may be considered as follows [1: (1) formation of
microcapsules [2; (2) adsorption onto the bacterial cell surface; (3) diffusion through
the cell wall; (4) binding to the cytoplasmic membrane; (5) disruption of the
cytoplasmic membrane; (6) release of the cytoplasmic constituents; (7) death of the
cell.
The hydrophilic block of the copolymer is easy to perform the process of (2) and
(3), while the hydrophobic block of the copolymer is facile to act the process of (3), (4)
and (5). And the amphiphilic structures are well-known to increase the permeability of
cell membrane and thus aid the killing process.
Figure S10.
Schematic illustration of the antibacterial process of diblock copolymers
to membrane of microbe: () formation of microcapsules () adsorption onto the
bacterial cell surface; () diffusion through the cell wall; () binding to the
cytoplasmic membrane; () disruption of the cytoplasmic membrane; () release of
the cytoplasmic constituents; () death of the cell.
The compare of the antibacterial activity between copolymer and homopolymer were
listed in Table S1.
Table S1. Diameter value of PS-b-PDMAEMA and PDMAEMA against E. coli,
S.aureus and M.albican.
Diameters(mm) PDMAEMA PS30-bE. coli
S.aureus
M.albican
PS15-b-
PS154-b-
(Mn=28,000)
PDMAEMA 21
PDMAEMA 163
PDMAEMA 72
1.5
3.5
1.5
2.0
4.0
0.5
1.0
3.5
1.0
1.5
3.0
1.5
According to the early knowledges, we think the PDMAEMA homopolymer or the copolymer
with high content PDMAEMA block will have the higher antibacterial activity than the lower
PDMAEMA content PS-b-PDMAEMA copolymer. But our experiment exhibit the interesting
results that is the copolymer which has the higher content PDMAEMA block is not the one has the
higher antibacterial activity. The probable reason is that during the process of kill microorganism,
there will be an effective hydrophilic and hydrophobic balance between PS and PDMAEMA block
after introduce PS hydrophobic component into the macromolecular chain. And also there must
have an optimal amphiphilic structure balance in such copolymer considering the antibacterial
activity which is accounted for by the contribution of the polymers to each elementary
process in the antimicrobial procession. The amphiphilic structure of the copolymer
will effectively adsorb onto the bacterial cell surface. Then the PS hydrophobic chains
diffuse through the cell wall and tightly binding to the cytoplasmic membrane. At last,
the copolymers disrupt the cytoplasmic membrane and release the cytoplasmic
constituents that result in the death of the cell.
S1. Ikeda, T.; Yamaguchi, H.; Tazuke, S. Antimicrob Agents Chemother 1984, 26, 139-144.
S2. Zhang, L. F., Eisenberg, A. J Am Chem Soc 1996, 118, 3168-3181.