Conjugated Oligoelectrolytes: Materials for Acceleration of Whole Cell

Subscriber access provided by University of South Dakota

Communication

Conjugated Oligoelectrolytes: Materials for Acceleration of Whole Cell Biocatalysis Bing Wang, Stephanie L. Fronk, Zachary Rengert, Jakkarin Limwongyut, and Guillermo C. Bazan Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.8b02848 • Publication Date (Web): 22 Aug 2018 Downloaded from http://pubs.acs.org on August 26, 2018

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 6 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

Chemistry of Materials

Conjugated Oligoelectrolytes: Materials for Acceleration of Whole Cell Biocatalysis Bing Wang§,†,‡, Stephanie L. Fronk,§,†,‡ Zachary Rengert†,‡, Jakkarin Limwongyut†,‡, and Guillermo C. Bazan†,‡,δ,* †

‡

δ

Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, Materials Department, University of California, Santa Barbara, California, 93106, United States.

ABSTRACT: Whole cell biocatalysis offers a way to generate products with high efficiency and low cost under mild reaction conditions. Biocatalytic conversions, however, can be limited by substrate and product diffusion across the cell membrane. Here, conjugated oligoelectrolytes (COEs) are shown to increase biocatalytic conversion rates, presumably by increasing membrane permeability. COEs with different backbone length and pendant groups, abbreviated as DSSN+, DSBN+, COE1-5C and COE1-4pyr, accelerated yeast biocatalysis using the model transformation of fumaric acid to L-malic acid. With good biocompatibility and membrane association, DSSN+ accelerated conversion rates 9-fold, relative to untreated controls, which is higher than with previously used, but more toxic, hexadecyltrimethylammonium bromide (5fold). DSBN+, with a shorter backbone conjugation length, grants a 14-fold increase, while the longer backbone of COE15C provides no improvement relative to the controls. The change of pendant cationic groups from tetraalkylammonium to pyridinium shows less impact than through modulation of backbone dimensions. These results demonstrate that COEs exhibit excellent potential for accelerating whole cell catalysis and reveal structure-function relationships for future optimization.

Biocatalysis refers to the application of enzymes or whole cells in chemical synthesis.1 Such bioconversion processes provide advantages that include mild reaction conditions, the capability for multistep reactions, high stereo-, regio-, and chemoselectivity, and relatively inexpensive purification protocols.2-4 Whole cell biocatalysis specifically is advantageous since the natural environment for enzymes and the ability of cells to regenerate cofactors are maintained.5-7 Membranes act as barriers that are beneficial to the cell since they prevent toxic compounds from entering and are critical to maintaining structural integrity.8, 9 However, membranes can present a potential hurdle in whole cell catalysis if substrates and/or products have difficulty crossing this barrier.10, 11 Methods to increase membrane permeability for improving biocatalysis have been developed, including treatment of cells with surfactants12-14 or solvents,15-17 and genetic engineering.18-21 Organic solvents and surfactants may not be ideal permeabilization methods, since they may be toxic to microbes and add complexity to product purification.22, 23 Genetic modification of microbes relevant for biocatalysis provides a powerful tool for optimization and can benefit from a synergistic approach through independent methods for membrane permeabilization.24 Thus, research in biocatalysis is a multidisciplinary area of research in which novel biocompatible systems that increase membrane permeability have the potential to play an important role. Conjugated oligoelectrolytes (COEs) are a class of materials characterized by a π-conjugated framework with

ionic pendant groups. Certain COEs intercalate into the membranes of microorganisms and subsequently alter their properties.25, 26 COEs can thereby increase the exoelectrogenic ability to E. coli and yeast microbial fuel cells25, 27-31 and have also been shown to increase the membrane permeability in Gram negative bacteria E. coli.32 If a similar increase in permeability can be achieved in yeast cells, which are characterized by a single doublelayer membrane, there is an opportunity to use such modified yeast for accelerated catalysis of relevant chemical reactions. Hence, we introduce four COE structures (structures and abbreviations are shown in Figure 1a; absorption and fluorescence spectra are provided in Figure S1) to yeast cells with the goal of increasing whole cell catalysis. These COEs were prepared as described in the literature.25, 28, 33 This idea is illustrated in cartoon format in Figure 1b. The conversion of fumaric acid to L-malic acid catalysed by Baker’s yeast (S. cerevisiae) cells, which is limited by transportation across the membrane, was chosen as a model reaction system.34-36 Fumarase, an enzyme located the in cytosol of yeast provides the catalytic function. Thus, the interaction of DSSN+ with yeast cells and its influence on the conversion of fumaric acid to L-malic acid was studied and compared with commonly used surfactant hexadecyltrimethylammonium bromide (CTAB). Furthermore, the effect of different COE chemical structures on the biocatalysis efficiency was examined in order to elucidate structure-function relationships relevant for future optimization.

ACS Paragon Plus Environment

Chemistry of 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

intensity from the rest of the cell decreased, which are consistent with the lipid membrane location of DSSN+. Cell association, low toxicity and localization in the lipid membrane provide the foundation for further examination of membrane permeabilization.

Figure 1. Illustration of COE structures and mechanism for accelerating biocatalysis. a) Molecular structures of COEs used in the study; b) Cartoon illustration of COE (green rectangle with pendant groups) intercalation into yeast lipid bilayer (orange and blue micelle structures) to accelerate the biocatalytic transformation of fumaric acid (black) to L-malic acid (Magenta). The diagram is not to scale and is only meant to be used to guide discussion.

Overall association with DSSN+ was determined via UV-Vis absorption as previously reported. 37, 38 Yeast cells were stained with DSSN+ in phosphate buffer for 2 h and then centrifuged down to the bottom. The absorbance at 420 nm of the supernatant was compared to a fresh solution of DSSN+, obtaining the amount of unabsorbed DSSN+ Cell association for DSSN+ was greater than 50% for all concentrations used in our study. Confocal laser scanning microscopy (CLSM) images of yeast cells were collected immediately after treatment with 25 μM DSSN+ and 5 μM propidium iodide (PI), a stain used to assess cell membrane damage. The successful staining of DSSN+ (green) is consistent with the association results obtained by absorption spectroscopy measurements and with accumulation in the cell membrane (Figure 2a).39 Most cells are not stained with PI, which indicates a high level of viability (Figure 2b and S2). That no PI is observed inside the cells after DSSN+ treatment indicates that there are no holes in the membrane. The biocompatibility of DSSN+ was also demonstrated by minimum inhibitory concentration (MIC) experiments, which provide a value > 128 μM (Table S1). This MIC value is higher than what is obtained with CTAB (16 μM). , The yeast cells also showed death rate of 13.2% and 66.7%, respectively, by flow cytometry analysis, after treating with 100 μM DSSN+ or CTAB for 2 h (Figure S3). To examine the possibility that COEs interact with the cell wall other than lipid membrane, fluorescence recovery after photobleaching (FRAP) was carried out. If located in lipid membrane, diffusion and fluorescence recovery of DSSN+ is anticipated due to the fluidity of membrane. From Figure 2d-f, one can observe that the fluorescence intensity from the bleached area recovered and that the

Figure 2. Good biocompatibility and membrane association of DSSN+ on Yeast Cells. a-c) CLSM images of yeast cells after staining with 25 μM DSSN+ and 5 μM PI: DSSN+ channel (a), PI channel (b) and bright field channel(c); the false color of DSSN+ and PI emission is green and red, respectively. d-f) Fluorescence intensity changes with time after photobleaching in bleached area (black curve and white arrow), unbleached area of the same cell (red curve and arrow) and unbleached whole cell (purple curve and arrow). CLSM images of DSSN+ stained yeast cells were taken right after bleaching (e) and 5 min later (f). The scale bars in CLSM images are 10 μm.

The L-malic acid production from fumaric acid by yeast cells was used to investigate catalytic activity. In these experiments, fresh wet yeast cells were treated with DSSN+ at six different concentrations. After washing, a 50 mM solution of fumaric acid was added to re-suspended cells, and the reaction was allowed to proceed at 30°C. Reactions were run in triplicate and the results at five time points were monitored by HPLC. Similar procedures were carried using untreated cells and cells stained CTAB for comparison. Figure 3a shows that L-malic acid production with non-treated yeast cells occurs in a manner consistent with literature precedent and that there is an increase in production with DSSN+.34, 35 After 21 hours, the concentration of L-malic acid in the reaction treated with 100 μM DSSN+ is 3.6 times larger than the control. CTAB also increases L-malic acid production, as established previously.36, 40, 41 The product concentration after 21 hours with [CTAB] = 100 μM is less than that of DSSN+ treated cells, at 2.1 times higher than the control (Figure 3b). Reaction rates were calculated by the increase of [Lmalic acid] per hour between 2.5 and 5 hours of reaction time. By dividing the reaction rate of treated cells by that of non-treated cells, a relative reaction rate (RRR) was calculated and used to evaluate the acceleration performance The RRR for DSSN+ treated cells increases linearly with [DSSN+] to 9-fold at 100 μM, while CTAB at the same concentration shows a 5-fold increase (Figure 3c).


Page 2 of 6

Page 3 of 6 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

Chemistry of Materials These data demonstrate that DSSN+ has the right selfassembling properties and can modify the organism appropriately to accelerate catalysis, presumably by increasing membrane permeabilization, as proposed in Figure 1b.

Similar trends as for DSSN+ in the production of Lmalic acid are observed with COE1-4pyr (Figure 4a). The RRR of COE1-4pyr treated cells increases with concentration and reached a plateau at 9-fold increase (Figure 4d). After 21 hours incubation, cells treated with 50 μM of DSBN+ or above produce ~4.5 times more L-malic acid than non-treated cells, and the RRR was circa 14 times larger than the control (Figure 4b and 4d). These results suggest that DSBN+ further increases membrane permeabilization in comparison with DSSN+. For COE1-5C, increasing staining concentration from 25 μM to 100 μM does not result in significantly improved biocatalytic yield or rate (Figure 4c and 4d). Cell association of COE1-5C was checked by UV-Vis absorption and was determined to be on the order of 40%. The presence of COE1-5C in the cell membrane was confirmed through CLSM images. Similar to DSSN+, most cells within the images are not stained with PI (Figure 4e-g and S4). The absence of biocatalytic enhancement is therefore not due to a failure of COE1-5C to insert into the yeast membrane or, as determined by MIC and CLSM, to cells being non-viable.

Figure 3. DSSN+ increases yeast cell biocatalysis activity and reusability. a-b) L-malic acid concentration vs. time as a function of DSSN+ (a) or CTAB (b) concentration. c) Relative reaction rate (RRR) of L-malic acid production as a function of DSSN+ or CTAB concentration. d) L-malic acid concentration vs. time for cells incubated with 100 μM DSSN+, and cells incubated with 100 μM CTAB after the first (solid line) and second (dash line) addition of 50 mM fumaric acid. All the error bars indicate the standard deviation.

DSSN+ treated cells were expected to be more capable of reuse than their CTAB treated counterparts on the basis of their lower MIC values and CLSM results. Cells treated with 100 μM DSSN+ or 100 μM CTAB were thus used to investigate to what extent catalytic activity could be maintained after the first cycle of testing. Cells were washed and collected after an initial 21 h run. No fluorescence of DSSN+ was detected in the supernatant, which demonstrates stable binding with the cell membrane. A second batch of 50 mM fumaric acid in buffer was subsequently added to re-suspended cells, and the reaction was allowed to proceed for another 21 hours under standard conditions. As shown in Figure 3d, cells initially treated with CTAB show a 50 % activity decrease in the second cycle, while DSSN+ treated cells maintain nearly identical catalytic activity. DSSN+ therefore exhibits the ability to increase the performance of cell biocatalysis with minimal impact on the viability of the cells. COEs other than DSSN+ were examined to understand the impact of molecular structure. Switching the cationic group from tetraalkylammonium in DSSN+ to pyridinium affords COE1-4pyr,33 while molecules named DSBN+ and COE1-5C were studied for probing backbone length variations (Figure 1a). MIC values were > 128 μM for COE14pyr and COE1-5C. DSBN+ was found to be more toxic than the other three COEs, with an MIC value of 50 μM.

Figure 4. Biocatalysis acceleration efficiency changes with COE structures. a-c) L-malic acid concentration vs. time as a function of COE1-4pyr (a), DSBN+ (b) or COE1-5C (c) concentration. d) Relative reaction rate (RRR) of L-malic acid production as a function of COE concentrations with nontreated cells as control. e-g) CLSM images of yeast cells after staining with 25 μM COE1-5C and 5 μM PI: COE1-5C channel (e), PI channel (f) and bright field channel (g). The false color of COE1-5C and PI emission is green and red, respectively. The scale bars in CLSM images are 10 μm.

The length of backbone shows a clear impact on the biocatalysis acceleration, while the change of pendant cationic group from tetraalkylammonium to pyridinium shows a negligible improvement (Figure 4d). As previ-



ously shown with molecular dynamics simulations, with an increase of total length of the backbone from three rings to five rings, the ability of COEs to thinner membrane decreases.42 Thus the shorter backbone length of DSBN+ results in increased membrane disruption and presumably greater permeabilization compared to DSSN+, while COE1-5C is shows no acceleration. DSSN+, DSBN+, COE1-4pyr, and COE1-5C were investigated for their ability to accelerate whole cell biocatalysis in a model biocatalytic transformation, specifically the conversion of fumaric acid to L-malic acid by yeast. Use of DSSN+, DSBN+, and COE1-4pyr led to increases in product yield and RRR compared to untreated yeast. This acceleration is attributed to an increase in membrane permeability. The comparison of DSSN+ and the conventional surfactant CTAB is particularly noteworthy, as it shows that COEs are capable of achieving larger acceleration rates, while maintaining a higher level of viability in the cells, particularly in reused cells. Comparison of DSSN+ and COE1-4pyr shows that the nature of the charged group does not impact greatly the overall reaction rate enhancement. In contrast the length of the conjugated framework yields significant differences in performance. Highest RRR values were observed with the shortest COE DSBN+, albeit at the expense of anticipated higher toxicity toward the cells. In contrast the longest molecule used in our studies, namely COE1-5C, does not provide an effect despite its efficient association with the cells. Such findings are consistent with previous simulation studies that show greater perturbation of the membrane through pinching of its structure as the length of the COE is decreased. Moreover, these findings thus indicate a strict correlation between molecular structure and the overall response by the microorganism targeted for use in biocatalysis. How and/or why COEs are capable of increasing permeability while at the same time providing a less toxic alternative remains poorly understood. We anticipate future opportunities in further understanding of the overall mechanisms of acceleration, as well as in practical applications that require a simple to use method of increasing whole cell biocatalysis.

ASSOCIATED CONTENT Supporting Information. The details of experimental procedures and supporting data are available. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author *G.C. Bazan. Email: [email protected]

Author Contributions B. W. and S.L. F. carried out the experiments, analyzed the data and wrote the manuscript. J. L. and Z. R. contributed to the confocal imaging experiments. Both B. W. and G.C. B. contributed to the final version of the manuscript. G.C. B. supervised the project. All authors have given approval to the

final version of the manuscript. ‡B.W. and S.L. F. contributed equally.

Funding Sources This work was supported by the Institute of Collaborative Biotechnologies through grant W911NF-09-0001 from the U.S. Army Research Office.

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT We acknowledge the use of the NRI-MCDB Microscopy Facility and the Spectra Laser Scanning Confocal supported by the Office of the Director, National Institutes of Health (S10OD010610-01A1).

ABBREVIATIONS COEs, conjugated oligoelectrolytes; CTAB, hexadecyltrimethylammonium bromide; CLSM, Confocal laser scanning microscopy; PI, propidium iodide; MIC, minimum inhibitory concentration; FRAP, fluorescence recovery after photobleaching.

REFERENCES (1) Bommarius, A. S.; Riebel-Bommarius, B. R., Biocatalysis: Fundamentals and Applications. Wiley-VCH: Weinheim, Germany, 2004. (2) de Carvalho, C. C. C. R., Whole cell biocatalysts: essential workers from Nature to the industry. Microb. Biotechnol. 2017, 10, 250-263. (3) Clomburg, J. M.; Crumbley, A. M.; Gonzalez, R., Industrial biomanufacturing: The future of chemical production. Science 2017, 355, eaag0804. (4) Schoemaker, H. E.; Mink, D.; Wubbolts, M. G., Dispelling the myths - Biocatalysis in industrial synthesis. Science 2003, 299, 16941697. (5) de Carvalho, C. C. C. R., Enzymatic and whole cell catalysis: Finding new strategies for old processes. Biotechnol. Adv. 2011, 29, 75-83. (6) Lin, B. X.; Tao, Y., Whole-cell biocatalysts by design. Microb. Cell. Fact. 2017, 16, 106. (7) France, S. P.; Hepworth, L. J.; Turner, N. J.; Flitsch, S. L., Constructing biocatalytic cascades: in vitro and in vivo approaches to de novo multi-enzyme pathways. ACS Catal. 2017, 7, 710-724. (8) Vanderrest, M. E.; Kamminga, A. H.; Nakano, A.; Anraku, Y.; Poolman, B.; Konings, W. N., the plasma-membrane of saccharomyces-cerevisiae - structure, function, and biogenesis. Microbiol Rev. 1995, 59, 304-322. (9) Nikaido, H., Molecular basis of bacterial outer membrane permeability revisited. Microbiol. Mol. Biol. Rev. 2003, 67, 593- 656. (10) Chen, R. R. Z., Permeability issues in whole-cell bioprocesses and cellular membrane engineering. Appl. Microbiol. Biotechnol. 2007, 74, 730-738. (11) Balasundaram, B.; Harrison, S.; Bracewell, D. G., Advances in product release strategies and impact on bioprocess design. Trends Biotechnol. 2009, 27, 477-485. (12) Gowda, L. R.; Bachhawat, N.; Bhat, S. G., Permeabilization of Bakers-yeast by cetyltrimethylammonium bromide for intracellular enzyme catalysis. Enzyme Microb. Technol. 1991, 13, 154-157. (13) Miozzari, G. F.; Niederberger, P.; Hutter, R., permeabilization of microorganisms by Triton X-100. Anal. Biochem. 1978, 90, 220-233. (14) Laouar, L.; Lowe, K. C.; Mulligan, B. J., Yeast responses to nonionic surfactants. Enzyme Microb. Technol. 1996, 18, 433-438.


Page 4 of 6

Page 5 of 6 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

Chemistry of Materials (15) Adamala, K. P.; Martin-Alarcon, D. A.; Guthrie-Honea, K. R.; Boyden, E. S., Engineering genetic circuit interactions within and between synthetic minimal cells. Nat. Chem. 2017, 9, 431-439. (16) Patel, T. N.; Park, A. H. A.; Bantat, S., genetic manipulation of outer membrane permeability: generating porous heterogeneous catalyst analogs in Escherichia coli. ACS Synth. Biol. 2014, 3, 848854. (17) Zhang, M.; Liang, Y. P.; Zhang, X. H.; Xu, Y.; Dai, H. P.; Xiao, W., Deletion of yeast CWP genes enhances cell permeability to genotoxic agents. Toxicol. Sci. 2008, 103, 68-76. (18) Liu, Y.; Hama, H.; Fujita, Y.; Kondo, A.; Inoue, Y.; Kimura, A.; Fukuda, H., Production of S-lactoylglutathione by high activity whole cell biocatalysts prepared by permeabilization of recombinant Saccharomyces cerevisiae with alcohols. Biotechnol. Bioeng. 1999, 64, 54-60. (19) Flores, M. V.; Voget, C. E.; Ertola, R. J. J., Permeabilization of yeast-cells (Kluyveromyces) with organic-solvents. Enzyme Microb. Technol. 1994, 16, 340-346. (20) Fenton, D. M., solvent treatment for beta-d-galactosidase release from yeast-cells. Enzyme Microb. Technol. 1982, 4, 229-232. (21) Laane, C.; Boeren, S.; Vos, K.; Veeger, C., rules for optimization of biocatalysis in organic solvents. Biotechnol. Bioeng. 2009, 102, 2-8. (22) Yang, K. M.; Lee, N. R.; Woo, J. M.; Choi, W.; Zimmermann, M.; Blank, L. M.; Park, J. B., Ethanol reduces mitochondrial membrane integrity and thereby impacts carbon metabolism of Saccharomyces cerevisiae. FEMS Yeast Res. 2012, 12, 675-684. (23) Fontanille, P.; Larroche, C., Optimization of isonovalal production from alpha-pinene oxide using permeabilized cells of Pseudomonas rhodesiae CIP 107491. Appl. Microbiol. Biotechnol. 2003, 60, 534-540. (24) Bornscheuer, U. T.; Huisman, G. W.; Kazlauskas, R. J.; Lutz, S.; Moore, J. C.; Robins, K., Engineering the third wave of biocatalysis. Nature 2012, 485, 185-194. (25) Garner, L. E.; Park, J.; Dyar, S. M.; Chworos, A.; Sumner, J. J.; Bazan, G. C., modification of the optoelectronic properties of membranes via insertion of amphiphilic phenylenevinylene oligoelectrolytes. J. Am. Chem. Soc. 2010, 132, 10042-10052. (26) Yan, H. J.; Catania, C.; Bazan, G. C., Membrane-Intercalating Conjugated Oligoelectrolytes: Impact on Bioelectrochemical Systems. Adv. Mater. 2015, 27, 2958-2973. (27) Du, J.; Thomas, A. W.; Chen, X. F.; Garner, L. E.; Vandenberg, C. A.; Bazan, G. C., Increased ion conductance across mammalian membranes modified with conjugated oligoelectrolytes. Chem. Commun. 2013, 49, 9624-9626. (28) Hou, H. J.; Chen, X. F.; Thomas, A. W.; Catania, C.; Kirchhofer, N. D.; Garner, L. E.; Han, A.; Bazan, G. C., conjugated oligoelectrolytes increase power generation in E. coli microbial fuel cells. Adv. Mater. 2013, 25, 1593-1597. (29) Wang, V. B.; Du, J.; Chen, X. F.; Thomas, A. W.; Kirchhofer, N. D.; Garner, L. E.; Maw, M. T.; Poh, W. H.; Hinks, J.; Wuertz, S.; Kjelleberg, S.; Zhang, Q. C.; Loo, J. S. C.; Bazan, G. C., Improving charge collection in Escherichia coli-carbon electrode devices with

conjugated oligoelectrolytes. Phys. Chem. Chem. Phys. 2013, 15, 5867-5872. (30) Wang, V. B.; Kirchhofer, N. D.; Chen, X. F.; Tan, M. Y. L.; Sivakumar, K.; Cao, B.; Zhang, Q. C.; Kjelleberg, S.; Bazan, G. C.; Loo, S. C. J.; Marsili, E., Comparison of flavins and a conjugated oligoelectrolyte in stimulating extracellular electron transport from Shewanella oneidensis MR-1. Electrochem. Commun. 2014, 41, 5558. (31) Zhao, C. E.; Chen, J.; Ding, Y. Z.; Wang, V. B.; Bao, B. Q.; Kjelleberg, S.; Cao, B.; Loo, S. C. J.; Wang, L. H.; Huang, W.; Zhang, Q. C., chemically functionalized conjugated oligoelectrolyte nanoparticles for enhancement of current generation in microbial fuel cells. ACS Appl. Mater. Inter. 2015, 7, 14501-14505. (32) Catania, C.; Ajo-Franklin, C. M.; Bazan, G. C., Membrane permeabilization by conjugated oligoelectrolytes accelerates wholecell catalysis. RSC Adv. 2016, 6, 100300-100306. (33) Thomas, A. W.; Catania, C.; Garner, L. E.; Bazan, G. C., Pendant ionic groups of conjugated oligoelectrolytes govern their ability to intercalate into microbial membranes. Chem. Commun. 2015, 51, 9294-9297.(34) Csuk, R.; Glanzer, B. I., Bakers-Yeast Mediated Transformations in Organic-Chemistry. Chem. Rev. 1991, 91, 49-97. (35) Lee, J. W.; Kim, H. U.; Choi, S.; Yi, J.; Lee, S. Y., Microbial production of building block chemicals and polymers. Curr. Opin. Biotechnol. 2011, 22, 758-767. (36) Panduric, N.; Salic, A.; Zelic, B., Fully integrated biotransformation of fumaric acid by permeabilized Baker's yeast cells with in situ separation of L-malic acid using ultrafiltration, acidification and electrodialysis. Biochem. Eng. J. 2017, 125, 221-229. (37) Catania, C.; Thomas, A. W.; Bazan, G. C., Tuning cell surface charge in E. coli with conjugated oligoelectrolytes. Chem. Sci. 2016, 7, 2023-2029. (38) Yan, H. J.; Rengert, Z. D.; Thomas, A. W.; Rehermann, C.; Hinks, J.; Bazan, G. C., Influence of molecular structure on the antimicrobial function of phenylenevinylene conjugated oligoelectrolytes. Chem. Sci. 2016, 7, 5714-5722.(39) Gwozdzinska, P.; Pawlowska, R.; Milczarek, J.; Garner, L. E.; Thomas, A. W.; Bazan, G. C.; Chworos, A., Phenylenevinylene conjugated oligoelectrolytes as fluorescent dyes for mammalian cell imaging. Chem. Commun. 2014, 50, 14859-14861. (40) Presecki, A. V.; Zelic, B.; Vasic-Racki, D., Comparison of the L-malic acid production by isolated fumarase and fumarase in permeabilized Baker's yeast cells. Enzyme Microb. Technol. 2007, 41, 605-612. (41) Stojkovic, G.; Znidarsic-Plazl, P., Continuous synthesis of Lmalic acid using whole-cell microreactor. Process Biochem. 2012, 47, 1102-1107. (42) Hinks, J.; Wang, Y. F.; Poh, W. H.; Donose, B. C.; Thomas, A. W.; Wuertz, S.; Loo, S. C. J.; Bazan, G. C.; Kjelleberg, S.; Mu, Y. G.; Seviour, T., Modeling cell membrane perturbation by molecules designed for transmembrane electron transfer. Langmuir 2014, 30, 2429-2440.




Page 6 of 6

Conjugated Oligoelectrolytes: Materials for Acceleration of Whole Cell

Recommend Documents