Antibacterial coatings of biomedical surfaces by polydextran aldehyde

Subscriber access provided by NEW MEXICO STATE UNIV

Article

Antibacterial coatings of biomedical surfaces by polydextran aldehyde/polyethylenimine nanofibers Qin Meng, Yingjun Li, and Chong Shen ACS Appl. Bio Mater., Just Accepted Manuscript • DOI: 10.1021/acsabm.8b00708 • Publication Date (Web): 27 Dec 2018 Downloaded from http://pubs.acs.org on January 5, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Bio Materials

Antibacterial coatings of biomedical surfaces by polydextran aldehyde/polyethylenimine nanofibers Qin Meng, Yingjun Li, Chong Shen*

1 College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, PR China

*Correspondence to: Dr. Chong Shen, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou, Zhejiang 310027, P.R. China. [email protected]

ACS Paragon Plus Environment

ACS Applied Bio Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract Hospital-acquired infections are predominately associated with bacteria colonization on surfaces of medical devices and implants. To reduce such infection, we report a simple method for antibacterial coating of various surfaces (eg. glasses and fabrics) at hospital site. As found, adhesive hydrogels made of polydextran aldehyde (PDA) and polyethylenimine (PEI) killed the three types of bacteria (E. coli, S. aureus and P. aeruginosa) with minimal inhibitory concentrations (MIC) at 9.8, 3.5 and 4.5 mg/mL. Then the antibacterial surfaces of glasses and fabrics were obtained via coating them by electrospinning of PDA/PEI nanofibers for 30 min. After coating, the surfaces could completely suppress the growth of E. coli, S. aureus and P. aeruginosa for up to 108 h of incubation, but still maintained their cytocompatiblity to fibroblasts. This surface coating is high effective and long-acting, showing potential applicability in suppressing bacterial infections. Keywords: antibacterial coating; bacteria; polyethylenimine; nanofiber; adhesive hydrogel

1. Introduction Hospital-acquired infections are considered as a major challenge in healthcare units worldwide 1. The prevalence rate of such infections generally ranges from 4-10% in developed countries but is typically higher (>15%) in the developing world 1. The infections are predominately associated with colonization of bacteria, especially Gram-negative bacterial pathogens that are more resistant to antibiotics, on surfaces of medical devices and implants 1-2. In this regard, antibacterial coatings of surfaces have been developed to prevent the bacterial colonization and further limit the infection spreading 3.


Page 2 of 26

Page 3 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


One of the major strategies for designing antibacterial coatings is so-called “antibacterial agent release”, where the biomedical surfaces are doped in an exogenous antibiotic for subsequent release

1, 4.

The antibacterial agents include antibiotics 5, antimicrobial peptides

6-7,

metal elements 8, and cationic compounds 9. However, the antibiotic activity of surfaces is eventually exhausted due to the release of active compounds over time (usually within 2 weeks) 10.

To overcome this limitation, the antibacterial agents are further covalently linked to material

surfaces by long polymeric chains

11-12,

which circumvents the reservoir exhaustion and thus

improves the antibacterial stability to at least 4 weeks 11. The adhered bacteria can be killed by contacting these agents, so that they perform antibacterial activities via mechanism of “contact-killing” 1. But unfortunately, the chemical modification of surfaces is inconvenient, high-cost and limited by material chemistry. Therefore, simple antibacterial coatings that can be easily carried out at hospital site are still urgently needed for modifying different surfaces of medical devices (eg. glasses, fabrics and metals). Bioadhesive hydrogels made of polydextran aldehyde (PDA) and polyethylenimine (PEI) have been reported to potently suppress the wound infection in murine models via the innate antibacterial properties of PEI 2. Hence, PDA/PEI hydrogels is expected to be a good surface coating due to their adhesive and antibacterial properties. To do that, this study develops a simple and efficient method for coating glass and fabric surfaces via electrospinning of PDA/PEI nanofibers (Figure 1A). Such surface coatings can kill both Gram-negative and Gram-positive bacteria, and the cytocompatiblity of the coated surfaces is not impaired as well.



2. Materials and methods 2.1 Synthesis of the polydextran aldehyde (PDA) Dextran (5 g, MW at 70 kDa, from Sigma-Aldrich) was firstly dissolved in 90 ml distilled water, and sodium periodate (3.35 g or 6.7 g, from Sigma-Aldrich) was then dissolved in 10 ml distilled water. The sodium periodate solution was added in portions to the dextran solution over 20 min with further stirring for 2 h in the dark. After that, the reaction mixture was extensively dialyzed (MWCO 3500 Da) against deionized water over 3 days with frequent water changes. The mixture was then lyophilized to obtain the products as a white solid. Aldehyde levels in the products were measured by reaction with hydroxylamine hydrochloride according to the previously reported method 13.

2.2. Fabrication of the PDA/PEI hydrogels Two branched polyethylenimine (PEI, from Aladdin Chem. Co Ltd, Shanghai, China) with different MW at 10 kDa and 70 kDa was dissolved in 10 mL deionized water, respectively. The resulting 10 wt% PEI solution was adjusted to pH 7.6 with HCl. Correspondingly, the PDA with different aldehyde levels (ie, 25% and 75% functionalized) was respectively dissolved in 10 mL milli-Q water at 10 wt%. As shown in Table 1, the PDA/PEI hydrogels formed by mixing the PEI and PDA solution at equal volumes. After allowing to form for 10 min at room temperature, the hydrogels were immersed into deionized water for at least 1 day before experiments.

2.3. Gelation time determination Pipette method was employed to determine the gelation time of the hydrogels as described


Page 4 of 26

Page 5 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


by Giano et al 2. Briefly, 500 µL of 10 wt% PDA solution and equal volume of 10 wt% PEI solution were added to an Eppendorf tube. The mixture solution was repeatedly pipetted up and down until it was impossible to pipette anymore. The time at which the solution could not be pipetted was defined as the gelation time. The average time was calculated from five independent measurements for each gel.

2.4. Bacteria culture E. coli (ATCC No. 25922) and S. aureus (ATCC No. 25923) were kindly provided by Dr. Xuwei Long in Nanjing University of Science and Technology. E. coli, S. aureus and P. aeruginosa (ATCC No. 39324) were all cultured in tryptic soy broth (TSB) at 37 °C and 200 rpm in a shaker-incubator (BSD-YX-3400, Boxun Co Ltd, Shanghai, China) for 12-18 h before use.

2.5 Antibacterial properties of the PDA/PEI hydrogels The PDA/PEI hydrogels used for antibacterial assessment were prepared by adding an equal volume (100 μl) of PEI solution to 100 μl PDA solution into a well in 24 well-plate. After well mixing the solution, the hydrogels were incubated at 37 °C for 30 min, and after which all the hydrogels were washed with phosphate buffer saline (PBS) for 3 times to remove any uncrosslinked polymers. For all the bacteria strains examined, the optical density at 625 nm (OD625) of bacteria suspension was adjusted to 1 AU via being detected in a microplate reader, M3, Molecular Device) by the adding TSB, corresponding to a 108 Colony-Forming Units per milliliter (CFU/ml) of stock bacteria solution. Then the stock was further diluted to 104 CFU/ml by TSB, and 1 ml was introduced to the surfaces of each hydrogel or tissue culture plate (TCP) as a



control for 24 h of incubation at 37 °C in an incubator (Thermo Forma 3111, Thermo Scientific) and then OD625 of the solution was measured by a microplate reader (M3, Molecular Device). The bacteria viability on TCPS was set as 100%, while the viability after hydrogel treatment was calculated by the equation as follows2:

bacteria viability % 

OD625  hydrogel   OD625 TSB  100% OD625 TCPS   OD625 TSB 

where OD625 (TSB) was the optical density of TSB without bacteria culture.

2.6 PDA/PEI nanofibers coatings on glass slides and cotton fibers As shown in Figure 1A, electrospinning was performed with a bifurcated steel capillary tube with 1 mm inside diameter tip connected to two syringes filled with 5 mL of the PEI-70 and PDA-25 solutions at 4 wt%, respectively. To facilitate the electrospinning, 2 wt% polyethylene oxide (PEO, 900 000 g/mol, from Sigma-Aldrich) was added into the PEI and PDA solutions before electrospinning process. The syringe pump (RSP 01-A; Ristron Co Ltd, Jiaxing, China) delivered solutions at flow rates of 0.15 ml/h with an applied voltage of 12 kV between the electrodes at distance of 10 cm using a high voltage power supplier (Tianjin Dongwen High Voltage Power Supply Co. Ltd. Tianjing, China). The electrospinning was carried out at room temperature in closed box with relative humidity at 40-50%. Morphology of the PDA/PEI nanofibers on glass and cotton surfaces was observed under fluorescence microscope (OLYMPUS Ix70) after stained by propidium iodide, or under scanning electron microscope (SEM, HITACHI TM-1000, Japan) after gold-palladium coating.


Page 6 of 26

Page 7 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2.7 Antibacterial properties of the PDA/PEI nanofiber coated surfaces Freshly grown bacteria at ~104 CFU/mL were individually added to the surfaces of glass slides and cotton fibers for 8 h of incubation with TSB at 37 °C under constant shaking. After removing the culture medium, the glass slides and cotton fibers were washed twice with 0.9% NaCl solution. The bacteria contaminated surfaces were then immersed into SYTO 9 (Invitrogen, ThermoFisher Scientific Co Ltd) and propidium iodide (PI, Invitrogen) in 0.9% NaCl solution at final concentrations of 3 μM and 20 μM, respectively. After 15 min of incubation in the dark, the surfaces were washed twice with 0.9% NaCl solution and imaged via a fluorescence microscope (OLYMPUS Ix70) at excitation of 488 nm for SYTO 9 and 530 nm for PI, respectively.

2.8 Detection on cytocompatibility of PDA/PEI nanofiber coated surfaces Human dermal fibroblasts were isolated simultaneously from normal human foreskin as previously described 14. Normal human foreskin was obtained from patients undergoing surgery, with written informed consent obtained from each patient. The study was performed in accordance with guidelines and regulations of Zhejiang University (Zhejiang, China) and approved by the Ethical and Research Committee of Zhejiang University. Human dermal fibroblasts were grown in DMEM with 10% FBS (Gibco, Invitrogen Co. Ltd, Canada) in CO2 incubator (Thermo Forma 3111, Thermo Scientific) until passage 3 to 5. The Calcein AM (Sigma-Aldrich Chemical Company)/PI staining was used for direct observation of living/dead fibroblasts. After 1 h of incubation with Calcein/PI solution (4 µM for each fluorescent probe in PBS), the materials was washed 3 times by PBS and viewed under a



Page 8 of 26

fluorescence microscope (OLYMPUS Ix70).

2.9 Statistical analysis All data were analyzed by means ± SD from three independent experiments. Comparisons between multiple groups were performed with the ANOVA test by SPSS. P-values less than 0.05 were considered statistically significant.

3. Results and discussion 3.1 Preparation and characterization of the PDA/PEI hydrogels PDA was synthesized by dextran oxidization with sodium periodate, and characterized by Fourier transform infrared (FT-IR) spectroscopy and 1H nuclear magnetic resonance (NMR). As shown in Figure S1, the new peak at 1734 cm-1 demonstrated the C=O stretching of the aldehyde group, indicating the existence of aldehyde groups in PDA-25 and PDA-75. Moreover, the PDA-75 presented higher peak at 1734 cm-1 than PDA-25, suggesting the higher oxidative degree in PDA-75. Correspondingly, the 1H NMR spectra of PDA-25 and PDA-75 showed the new peaks at 9.63 ppm (Figure S2), consisting with previously reported spectra on aldehyde groups

15.

For

further quantitative assay on the oxidative degree of dextran, PDA was measured by reaction with hydroxylamine hydrochloride. As found, PDA-25 and PDA-75 respectively performed the oxidative degree of 24.76% and 75.51%, which was comparable to other studies at range of 30-70%

16-18.

Hence, the two PDAs were named as PDA-25 and PDA-75 according to their

oxidative degree. By mixing the two PDAs with two PEIs (MW at 10 kDa and 70 kDa, named as PEI-10 and


Page 9 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


PEI-70) respectively, the PDA/PEI hydrogels formed within 60 seconds (Figure 1 B and C), consistent with the previously reported PDA/PEI hydrogels 2. The four hydrogels were named as PDA-25+PEI-10, PDA-25+PEI-70, PDA-75+PEI-10 and PDA-75+PEI-70. As shown in Figure 1C, increase on either oxidative degree of PDA or MW of PEI accelerated the hydrogel gelation. Among the four hydrogels, the formation of PDA-75+PEI-70 was fastest (within 3 seconds). Besides, the decrease of pH significantly extended the gelation as shown in Figure 1D, and the hydrogels could not form at pH 5, while the acid environments dramatically dissolved the PDA/PEI nanofibers (Figure S6-C). In this regard, the coatings were very adhesive under physiological environments, possibly due to the strong tendency of PEI to adsorb to solid surfaces

23.

Such stable coatings may facilitate their

modification on medical devices. Figure 3 illustrated the morphology of nanofibers on glasses (A-B) and cotton fibers (C-D). After stained by propidium iodide solution, the nanofibers displayed red fluorescence under microscopy observation (Figure 3A). The nanofibers on glass surfaces were about 100 nm in diameter and random coils/beads could be seen on the fibers (Figure 3B), while the surfaces of cotton fibers were twined round by the nanofibers (Figure 3D).

3.4 Antibacterial properties of the PDA/PEI nanofibers coated surfaces Live/dead bacterial viability assay was performed to further detect the antibacterial activity of the PDA/PEI nanofibers coated surfaces. As shown in Figure 4, a large number of live bacteria (stained green by Syto 9) were found on the uncoated glass surfaces. However, the nanofiber coated surfaces killed most of P. aeruginosa and S. aureus, as well as about half of E. coli (Figure



Page 12 of 26

4A-C). The uncoated cotton fibers were similarly adhered by a lot of live bacteria (Figure 5D-F), while the number of bacteria on the coated cotton fibers was much less and few of the bacteria were alive (Figure 5A-C). By quantitatively determination of the bacterial viability, the modified glass and cotton surfaces killed over 70% of E. coli, 80% of S. aureus and 90% of P. aeruginosa (Figure 6A), showing slightly weaker antibacterial ability than that of the corresponding PDA/PEI hydrogel (Figure 2 and Figure S-5). It was possibly because the surfaces were not completely covered by the nanofibers (Figure 3). Nevertheless, the modified surfaces both maintained their antibacterial effects up to 108 h of incubation (Figure 6B-D). The inhibited bacteria growth by the coatings might greatly reduce the biofilm formation that was mainly induced by the increased cell numbers 24, and thus well suppress the infections of medical devices.

3.5 Compatibility of the nanofiber coated surfaces to fibroblasts Unlike other cationic compounds that led to cytotoxicity

25-26,

the PDA/PEI coated surfaces

showed good compatibility to fibroblasts (Figure 7). The fibroblasts on the coated glass surfaces were alive (stained green by Calcein-AM, as shown in Figure 7B) and the cell viability has no significant difference to that on the uncoated surfaces (Figure 7A). Similarly, the fibroblasts on the coated cotton fibers were also alive (Figure 7C) and some of them well adhered and spread along the cotton fibers (Figure 7D). Moreover, the fibroblasts on the coated surfaces grew as fast as those on the uncoated surfaces (Figure S7). As the PEI itself has been reported to display high cytotoxicity to osteoblasts and fibroblasts in vitro 27, its binding with PDA seemed to largely attenuate the toxicity via the immobilization


Page 13 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


within the hydrogels. However, the PDA/PEI hydrogels as bulks, though did not kill the cells on the surfaces (Figure S8), could not support the spreading and proliferation of the fibroblasts. In this regard, we assumed that the incompletely covered surfaces by the nanofibers provided the adhesive area to fibroblasts and the existence of nanofibers at appropriated density did not hamper the adhesion and spreading of fibroblasts.

4. Conclusion The PDA/PEI hydrogels showed potent antibacterial properties to Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli and P. aeruginosa) with MIC at 3.5, 9.8 and 4.5 mg/mL. By coating the glass and fabric surfaces via the PDA/PEI nanofibers for 30 min of electrospinning, these surfaces gained good anti-bacterial abilities against E. coli, S. aureus and P. aeruginosa for up to 108 h of incubation as well. At the same time, the coated surfaces sustained their cytocompatiblity to fibroblasts. Hence, this method for surface coating is high effective and long-acting, showing potential values in suppressing hospital-acquired infections.

5. Conflicts of interest There are no conflicts of interest to declare. Supporting Information:

Characterization on hydrogels, anti-bacterial functions of the PDA/PEI hydrogels and the cytocompatiblity of PDA/PEI nanofibers

6. Acknowledgement We gratefully acknowledge the financial support of this study by NSFC (National Natural



Science Foundation of China, No 21776242).

7. Reference 1.

Cloutier, M.; Mantovani, D.; Rosei, F., Antibacterial Coatings: Challenges, Perspectives, and

Opportunities. Trends Biotechnol. 2015, 33 (11), 637-652. 2.

Giano, M. C.; Ibrahim, Z.; Medina, S. H.; Sarhane, K. A.; Christensen, J. M.; Yamada, Y.;

Brandacher, G.; Schneider, J. P., Injectable Bioadhesive Hydrogels with Innate Antibacterial Properties. Nat. Commun. 2014, 5, 4095. 3.

Hasan, J.; Crawford, R. J.; Ivanova, E. P., Antibacterial Surfaces: The Quest for a New Generation

of Biomaterials. Trends Biotechnol. 2013, 31 (5), 295-304. 4.

Campoccia, D.; Montanaro, L.; Arciola, C. R., A Review of the Clinical Implications of

Anti-Infective Biomaterials and Infection-Resistant Surfaces. Biomaterials 2013, 34 (33), 8018-8029. 5.

Campoccia, D.; Montanaro, L.; Arciola, C. R., A Review of the Biomaterials Technologies for

Infection-Resistant Surfaces. Biomaterials 2013, 34 (34), 8533-8554. 6.

Lazar, V.; Martins, A.; Spohn, R.; Daruka, L.; Grezal, G.; Fekete, G.; Szamel, M.; Jangir, P. K.;

Kintses, B.; Csorgo, B.; Nyerges, A.; Gyorkei, A.; Kincses, A.; Der, A.; Walter, F. R.; Deli, M. A.; Urban, E.; Hegedus, Z.; Olajos, G.; Mehi, O.; Balint, B.; Nagy, I.; Martinek, T. A.; Papp, B.; Pal, C., Antibiotic-Resistant Bacteria Show Widespread Collateral Sensitivity to Antimicrobial Peptides. Nat. Microbiol. 2018, 3 (6), 718-731. 7.

Brogden, K. A., Antimicrobial Peptides: Pore Formers or Metabolic Inhibitors in Bacteria? Nat.

Rev. Microbiol. 2005, 3 (3), 238-250. 8.

Jo, Y. K.; Seo, J. H.; Choi, B. H.; Kim, B. J.; Shin, H. H.; Hwang, B. H.; Cha, H. J.,

Surface-Independent Antibacterial Coating Using Silver Nanoparticle-Generating Engineered Mussel Glue. ACS App. Mater.Inter. 2014, 6 (22), 20242-20253. 9.

Yang, Y. C.; Cai, Z. G.; Huang, Z. H.; Tang, X. Y.; Zhang, X., Antimicrobial Cationic Polymers: From

Structural Design to Functional Control. Polymer J. 2018, 50 (1), 33-44. 10. Phuengkham, H.; Nasongkla, N., Development of Antibacterial Coating on Silicone Surface Via Chlorhexidine-Loaded Nanospheres. J Mater. Sci. Mater. Med. 2015, 26 (2), 78. 11. Godoy-Gallardo, M.; Wang, Z. J.; Shen, Y.; Manero, J. M.; Gil, F. J.; Rodriguez, D.; Haapasale, M., Antibacterial Coatings on Titanium Surfaces: A Comparison Study between in Vitro Single-Species and Multispecies Biofilm. ACS App. Mater.Inter. 2015, 7 (10), 5992-6001. 12. Ding, X.; Yang, C.; Lim, T. P.; Hsu, L. Y.; Engler, A. C.; Hedrick, J. L.; Yang, Y. Y., Antibacterial and Antifouling Catheter Coatings Using Surface Grafted Peg-B-Cationic Polycarbonate Diblock Copolymers. Biomaterials 2012, 33 (28), 6593-6603. 13. Zhao, H.; Heindel, N. D., Determination of Degree of Substitution of Formyl Groups in Polyaldehyde Dextran by the Hydroxylamine Hydrochloride Method. Pharm Res 1991, 8 (3), 400-402. 14. Tenchini, M. L.; Ranzati, C.; Malcovati, M., Culture Techniques for Human Keratinocytes. Burns 1992, 18 Suppl 1, S11-16. 15. Boehnke, N.; Cam, C.; Bat, E.; Segura, T.; Maynard, H. D., Imine Hydrogels with Tunable Degradability for Tissue Engineering. Biomacromolecules 2015, 16 (7), 2101-2108. 16. Sivakumaran, D.; Maitland, D.; Hoare, T., Injectable Microgel-Hydrogel Composites for Prolonged Small-Molecule Drug Delivery. Biomacromolecules 2011, 12 (11), 4112-4120.


Page 14 of 26

Page 15 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


17. Yamada, Y.; Schneider, J. P., Fragmentation of Injectable Bioadhesive Hydrogels Affords Chemotherapeutic Macromolecules. Biomacromolecules 2016, 17 (8), 2634-2641. 18. Hudson, S. P.; Langer, R.; Fink, G. R.; Kohane, D. S., Injectable in Situ Cross-Linking Hydrogels for Local Antifungal Therapy. Biomaterials 2010, 31 (6), 1444-1452. 19. Li, L.; Wang, C. P.; Huang, Q.; Xiao, J. R.; Zhang, Q.; Cheng, Y. Y., A Degradable Hydrogel Formed by Dendrimer-Encapsulated Platinum Nanoparticles and Oxidized Dextran for Repeated Photothermal Cancer Therapy. J Mater. Chem. B 2018, 6 (16), 2474-2480. 20. Pasquarella, C.; Pitzurra, O.; Savino, A., The Index of Microbial Air Contamination. J Hospit.Infect. 2000, 46 (4), 241-256. 21. Helander, I. M.; Alakomi, H. L.; LatvaKala, K.; Koski, P., Polyethyleneimine Is an Effective Permeabilizer of Gram-Negative Bacteria. Microbiology-Uk 1997, 143, 3193-3199. 22. Wiegand, C.; Bauer, M.; Hipler, U. C.; Fischer, D., Poly(Ethyleneimines) in Dermal Applications: Biocompatibility and Antimicrobial Effects. Intern. J Pharm. 2013, 456 (1), 165-174. 23. Gong, X. J.; Ngai, T., Interactions between Solid Surfaces with Preadsorbed Poly(Ethylenimine) (Pei) Layers: Effect of Unadsorbed Free Pei Chains. Langmuir 2013, 29 (20), 5974-5981. 24. Flemming, H. C.; Wingender, J.; Szewzyk, U.; Steinberg, P.; Rice, S. A.; Kjelleberg, S., Biofilms: An Emergent Form of Bacterial Life. Nat. Rev. Microbiol. 2016, 14 (9), 563-575. 25. Wei, X. W.; Shao, B.; He, Z. Y.; Ye, T. H.; Luo, M.; Sang, Y. X.; Liang, X.; Wang, W.; Luo, S. T.; Yang, S. Y.; Zhang, S.; Gong, C. Y.; Gou, M. L.; Deng, H. X.; Zhao, Y. L.; Yang, H. S.; Deng, S. Y.; Zhao, C. J.; Yang, L.; Qian, Z. Y.; Li, J.; Sun, X.; Han, J. H.; Jiang, C. Y.; Wu, M.; Zhang, Z. R., Cationic Nanocarriers Induce Cell Necrosis through Impairment of Na+/K+-Atpase and Cause Subsequent Inflammatory Response. Cell Res. 2015, 25 (2), 237-253. 26. Maenpaa, H.; Toimela, T.; Mannerstrom, M.; Saransaari, P.; Tahti, H., Toxicity of Selected Cationic Drugs in Retinoblastomal Cultures and in Cocultures of Retinoblastomal and Retinal Pigment Epithelial Cell Lines. Neurochem. Res. 2004, 29 (1), 305-311. 27. Brunot, C.; Ponsonnet, L.; Lagneau, C.; Farge, P.; Picart, C.; Grosgogeat, B., Cytotoxicity of Polyethyleneimine (Pei), Precursor Base Layer of Polyelectrolyte Multilayer Films. Biomaterials 2007, 28 (4), 632-640.



Page 16 of 26

Table Table 1 Molecule weight of PDA/PEI and functionalized ratio of PDA. Polymer

MW

Functionalized ratio

PDA-25 PDA-75 PEI-10 PEI-70

70 kDa 70 kDa 10 kDa 70 kDa

25% 75% ---


Page 17 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table 2 Determination of the MIC90 (minimal inhibitory concentrations, 90% bacteria dead) for P. aeruginosa, S. aureus and E. coli after incubation with PDA-25+PEI-70 hydrogels for 24 h.

MIC90 (mg/mL, dry base)

P. aeruginosa

S. aureus

E. coli

4.5

3.5

9.8



Figure legends Figure 1 (A) Design of PDA/PEI nanofibers for antibacterial coatings. (B) Formation of PDA/PEI hydrogel. (C, D) Gelation time of PDA/PEI hydrogels. *p

Antibacterial coatings of biomedical surfaces by polydextran aldehyde

Recommend Documents