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Article ; Online: A Simplified Direct Lipid Mixing Lipoplex Preparation: Comparison of Liposomal-, Dimethylsulfoxide-, and Ethanol-Based Methods.

Meisel, Joseph W / Gokel, George W

2016 Volume 6, Page(s) 27662

Abstract: Established transfection methodology often uses commercial reagents, which must be formed into liposomes in a sequence of about half a dozen steps. The simplified method reported here is a direct lipid mixing approach that requires fewer steps, less ... ...

Abstract	Established transfection methodology often uses commercial reagents, which must be formed into liposomes in a sequence of about half a dozen steps. The simplified method reported here is a direct lipid mixing approach that requires fewer steps, less manipulation, and is less time-consuming. Results are comparable to those obtained with more commonly used methods, as judged by a variety of analytical techniques and by comparisons of transfection results. The method reported here may be applied to non-liposome-forming compounds, thereby greatly expanding the range of structures that can be tested for transfection ability.
MeSH term(s)	DNA/administration & dosage ; DNA/chemistry ; DNA/genetics ; Dimethyl Sulfoxide/chemistry ; Ethanol/chemistry ; Gene Transfer Techniques ; Lipids/chemistry ; Lipids/genetics ; Lipids/pharmacology ; Liposomes/chemistry ; Liposomes/pharmacology ; Transfection/methods
Chemical Substances	Lipids ; Liposomes ; Ethanol (3K9958V90M) ; DNA (9007-49-2) ; Dimethyl Sulfoxide (YOW8V9698H)
Language	English
Publishing date	2016-06-21
Publishing country	England
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/srep27662
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Article ; Online: Assessment of a host-guest interaction in a bilayer membrane model.

Kumari, Harshita / Negin, Saeedeh / Eisenhart, Andrew / Patel, Mohit B / Beck, Thomas L / Heinrich, Frank / Spikes, Helena J / Gokel, George W

RSC advances

2022 Volume 12, Issue 49, Page(s) 32046–32055

Abstract: Supramolecular interactions are well recognized and many of them have been extensively studied in chemistry. The formation of supramolecular complexes that rely on weak force interactions are less well studied in bilayer membranes. Herein, a supported ... ...

Abstract	Supramolecular interactions are well recognized and many of them have been extensively studied in chemistry. The formation of supramolecular complexes that rely on weak force interactions are less well studied in bilayer membranes. Herein, a supported bilayer membrane is used to probe the penetration of a complex between tetracycline and a macrocyclic polyether. In a number of bacterial systems, the presence of the macrocycle has been found to significantly enhance the potency of the antimicrobial
Language	English
Publishing date	2022-11-10
Publishing country	England
Document type	Journal Article
ISSN	2046-2069
ISSN (online)	2046-2069
DOI	10.1039/d2ra03851j
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Article: Antimicrobial and Adjuvant Potencies of Di-

Patel, Mohit B / Spikes, Helena / Bailey, Robert S / Connell, Thomas / Gill, Hannah / Gokel, Michael R / Harris, Rebecca / Meisel, Joseph W / Negin, Saeedeh / Yin, Shanheng Andrew / Gokel, George W

Antibiotics (Basel, Switzerland)

2023 Volume 12, Issue 10

Abstract: Lariat ethers are macrocyclic polyethers-crown ethers-to which sidearms are appended. 4,13-Diaza-18-crown-6 having twin alkyl chains at the nitrogens show biological activity. They exhibit antibiotic activity, but when co-administered at with an FDA- ... ...

Abstract	Lariat ethers are macrocyclic polyethers-crown ethers-to which sidearms are appended. 4,13-Diaza-18-crown-6 having twin alkyl chains at the nitrogens show biological activity. They exhibit antibiotic activity, but when co-administered at with an FDA-approved antibiotic, the latter's potency is often strongly enhanced. Potency enhancements and resistance reversals have been documented in vitro for a range of Gram-negative and Gram-positive bacteria with a variety of antimicrobials. Strains of
Language	English
Publishing date	2023-10-05
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2681345-2
ISSN	2079-6382
ISSN	2079-6382
DOI	10.3390/antibiotics12101513
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Article ; Online: Synthetic ion channels: from pores to biological applications.

Gokel, George W / Negin, Saeedeh

Accounts of chemical research

2013 Volume 46, Issue 12, Page(s) 2824–2833

Abstract: In this Account, we describe the development of several diverse families of synthetic, membrane-active amphiphiles that form pores and facilitate transport within membrane bilayers. For the most part, the compounds are amphiphiles that insert into the ... ...

Abstract	In this Account, we describe the development of several diverse families of synthetic, membrane-active amphiphiles that form pores and facilitate transport within membrane bilayers. For the most part, the compounds are amphiphiles that insert into the bilayer and form pores either on their own or by self-assembly. The first family of synthetic ion channels prepared in our lab, the hydraphiles, used crown ethers as head groups and as a polar central element. In a range of biophysical studies, we showed that the hydraphiles formed unimolecular pores that spanned the bilayer. They mediated the transport of Na(+) and K(+) but were blocked by Ag(+). The hydraphiles are nonrectifying and disrupt ion homeostasis. As a result, these synthetic ion channels are toxic to various bacteria and yeast, a feature that has been used therapeutically in direct injection chemotherapy. We also developed a family of amphiphilic heptapeptide ion transporters that selected Cl(-) >10-fold over K(+) and showed voltage dependent gating. The formed pores were approximately dimeric, and variations in the N- and C-terminal anchor chains and the acids affected transport rates. Surprisingly, the longer N-terminal anchor chains led to less transport but greater Cl(-) selectivity. A proline residue, which is present in the ClC protein channel's conductance pore, proved to be critical for Cl(-) transport selectivity. Pyrogallol[4]arenes are macrocycles formed by acid-catalyzed condensation of four 1,2,3- trihydroxybenzenes with four aldehydes. The combination of 12 hydroxyl groups on one face of the macrocycle and four pendant alkyl chains conferred considerable amphiphilicity to these compounds. The pyrogallol[4]arenes inserted into bilayer membranes and conducted ions. Based on our experimental evidence, the ions passed through a self-assembled pore comprising four or five amphiphiles rather than passing through the central opening of a single macrocycle. Pyrogallol[4]arenes constructed with branched chains are also amphiphilic and active in membranes. The pyrogallol[4]arene with 3-pentyl sidechains formed a unique nanotube assembly and functioned as an ion channel in bilayer membranes. Finally, we showed that dianilides of either isophthalic or dipicolinic acids, compounds which have been extensively studied as anion binders, can self-assemble to form pores within bilayers. We called these dianilides tris-arenes and have shown that they readily bind to phosphate anions. These structures also mediated the transport of DNA plasmids through vital bilayer membranes in the bacterium Escherichia coli and in the yeast Saccharomyces cerevisiae . This transformation or transfection process occurred readily and without any apparent toxicity or mutagenicity.
MeSH term(s)	Anion Transport Proteins/chemistry ; Biological Transport ; Biphenyl Compounds/chemistry ; Calixarenes/chemistry ; DNA/chemistry ; Ethanolamines/chemistry ; Ion Channels/chemistry ; Porosity
Chemical Substances	Anion Transport Proteins ; Biphenyl Compounds ; Ethanolamines ; Ion Channels ; aplosspan ; Calixarenes (130036-26-9) ; DNA (9007-49-2)
Language	English
Publishing date	2013-12-17
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S. ; Review
ZDB-ID	1483291-4
ISSN	1520-4898 ; 0001-4842
ISSN (online)	1520-4898
ISSN	0001-4842
DOI	10.1021/ar400026x
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Article ; Online: Synthetic ionophores as non-resistant antibiotic adjuvants.

Patel, Mohit B / Garrad, Evan / Meisel, Joseph W / Negin, Saeedeh / Gokel, Michael R / Gokel, George W

RSC advances

2019 Volume 9, Issue 4, Page(s) 2217–2230

Abstract: Antimicrobial resistance is a world-wide health care crisis. New antimicrobials must both exhibit potency and thwart the ability of bacteria to develop resistance to them. We report the use of synthetic ionophores as a new approach to developing non- ... ...

Abstract	Antimicrobial resistance is a world-wide health care crisis. New antimicrobials must both exhibit potency and thwart the ability of bacteria to develop resistance to them. We report the use of synthetic ionophores as a new approach to developing non-resistant antimicrobials and adjuvants. Most studies involving amphiphilic antimicrobials have focused on either developing synthetic amphiphiles that show ion transport, or developing non-cytotoxic analogs of such peptidic amphiphiles as colistin. We have rationally designed, prepared, and evaluated crown ether-based synthetic ionophores ('hydraphiles') that show selective ion transport through bilayer membranes and are toxic to bacteria. We report here that hydraphiles exhibit a broad range of antimicrobial properties and that they function as adjuvants in concert with FDA-approved antibiotics against multi-drug resistant (MDR) bacteria. Studies described herein demonstrate that benzyl C
Language	English
Publishing date	2019-01-17
Publishing country	England
Document type	Journal Article
ISSN	2046-2069
ISSN (online)	2046-2069
DOI	10.1039/c8ra07641c
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Article ; Online: Synthetic membrane active amphiphiles.

Gokel, George W / Negin, Saeedeh

Advanced drug delivery reviews

2012 Volume 64, Issue 9, Page(s) 784–796

Abstract: During the past several decades, various synthetic organic compounds that form pores in bilayer membranes have been prepared and studied. These membrane active amphiphiles have also proved to be useful in affecting the transport of molecules into or ... ...

Abstract	During the past several decades, various synthetic organic compounds that form pores in bilayer membranes have been prepared and studied. These membrane active amphiphiles have also proved to be useful in affecting the transport of molecules into or through the bilayer. This article discusses the evolution of these compounds and exemplifies recent applications such as enhancement of antimicrobial activity.
MeSH term(s)	Anti-Infective Agents/chemistry ; Biological Transport ; Drug Delivery Systems/methods ; Humans ; Lipid Bilayers/chemistry ; Membranes, Artificial ; Surface-Active Agents/chemistry
Chemical Substances	Anti-Infective Agents ; Lipid Bilayers ; Membranes, Artificial ; Surface-Active Agents
Language	English
Publishing date	2012-06-15
Publishing country	Netherlands
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S. ; Review
ZDB-ID	639113-8
ISSN	1872-8294 ; 0169-409X
ISSN (online)	1872-8294
ISSN	0169-409X
DOI	10.1016/j.addr.2012.01.011
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Article: The aromatic sidechains of amino acids as neutral donor groups for alkali metal cations.

Gokel, George W

Chemical communications (Cambridge, England)

2003 , Issue 23, Page(s) 2847–2852

Abstract: An aromatic residue that can serve as a pi-donor occurs in all known protein sequences about one out of every 11 amino acids. Benzene, phenol, and indole, the sidechains of phenylalanine, tyrosine, and tryptophan, are particularly important in protein ... ...

Abstract	An aromatic residue that can serve as a pi-donor occurs in all known protein sequences about one out of every 11 amino acids. Benzene, phenol, and indole, the sidechains of phenylalanine, tyrosine, and tryptophan, are particularly important in protein structure. Solid state structures confirm the interactions of these neutral arenes, along with double and triple bonds, with sodium and potassium cations.
MeSH term(s)	Amino Acids, Aromatic/chemistry ; Amino Acids, Essential/chemistry ; Cations/chemistry ; Computer Simulation ; Metals, Alkali/chemistry
Chemical Substances	Amino Acids, Aromatic ; Amino Acids, Essential ; Cations ; Metals, Alkali
Language	English
Publishing date	2003-09-01
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, U.S. Gov't, P.H.S. ; Review
ZDB-ID	1472881-3
ISSN	1364-548X ; 1359-7345 ; 0009-241X
ISSN (online)	1364-548X
ISSN	1359-7345 ; 0009-241X
DOI	10.1039/b305483g
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Article: Reversal of Tetracycline Resistance in Escherichia coli by Noncytotoxic bis(Tryptophan)s

Meisel, Joseph W / Garrad Evan / Gokel George W / Patel Mohit B / Stanton Ryan A

Journal of the American Chemical Society. 2016 Aug. 24, v. 138, no. 33

2016

Abstract: Nine bis(tryptophan) derivatives (BTs) and two control compounds were synthesized and tested for antimicrobial activity against two Escherichia coli strains and a Staphylococcus aureus strain. The effects of linker type, shape, and conformational ... ...

Abstract	Nine bis(tryptophan) derivatives (BTs) and two control compounds were synthesized and tested for antimicrobial activity against two Escherichia coli strains and a Staphylococcus aureus strain. The effects of linker type, shape, and conformational rigidity were manifested in dramatic differences in altering tetracycline potency when coadministered with that antibiotic. A reversal of resistance was observed for an E.Â coli strain having a TetA efflux pump. Survival of mammalian cells was assayed with good result.
Keywords	antibacterial properties ; Escherichia coli ; mammals ; Staphylococcus aureus ; tetracycline ; transporters
Language	English
Dates of publication	2016-0824
Size	p. 10571-10577.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	3155-0
ISSN	1520-5126 ; 0002-7863
ISSN (online)	1520-5126
ISSN	0002-7863
DOI	10.1021%2Fjacs.6b05578
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Article: Coordination and transport of alkali metal cations through phospholipid bilayer membranes by hydraphile channels.

Gokel, George W / Daschbach, Megan Michele

Coordination chemistry reviews

2009 Volume 252, Issue 8-9, Page(s) 886–902

Abstract: Hydraphiles are synthetic ionophores that were designed to mimic some properties of protein channels that conduct such cations as sodium. They use macrocyclic (crown) polyethers as amphiphilic headgroups and as entry and exit portals. Their overall ... ...

Abstract	Hydraphiles are synthetic ionophores that were designed to mimic some properties of protein channels that conduct such cations as sodium. They use macrocyclic (crown) polyethers as amphiphilic headgroups and as entry and exit portals. Their overall length is controlled by covalent links between the two headgroups (distal macrocycles) and the "central relay" unit, typically also an azacrown. The hydraphiles insert in the bilayer membranes of synthetic phospholipid vesicles or vital cells and mediate the transport of cations. The hydraphiles were intended to be models but they are functional channels. Because they are symmetric, they are non-rectifying but they show open-close behavior characteristic of natural channels. Because they are non-rectifying, when they insert into a microbial membrane, they lead to a rapid change in osmotic balance that proves fatal to bacteria.
Language	English
Publishing date	2009-01-08
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	217255-0
ISSN	0010-8545
ISSN	0010-8545
DOI	10.1016/j.ccr.2007.07.026
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Article: Fluorescent, synthetic amphiphilic heptapeptide anion transporters: evidence for self-assembly and membrane localization in liposomes.

You, Lei / Gokel, George W

Chemistry (Weinheim an der Bergstrasse, Germany)

2008 Volume 14, Issue 19, Page(s) 5861–5870

Abstract: Synthetic anion transporters (SATs) of the general type (n-C18H37)2N-COCH2OCH2CO-(Gly)3-Pro-(Gly)3-O-n-C7H15, 1, are amphiphilic peptides that form anion-conducting pores in bilayer membranes. To better understand membrane insertion, assembly and ... ...

Abstract	Synthetic anion transporters (SATs) of the general type (n-C18H37)2N-COCH2OCH2CO-(Gly)3-Pro-(Gly)3-O-n-C7H15, 1, are amphiphilic peptides that form anion-conducting pores in bilayer membranes. To better understand membrane insertion, assembly and aggregation dynamics, and membrane penetration, four novel fluorescent structures were prepared for use in both aqueous buffer and phospholipid bilayers. The fluorescent residues pyrene, indole, dansyl, and NBD were incorporated into 1 to give 2, 3, 4, and 5, respectively. Assembly of peptide amphiphiles in buffer was confirmed by monitoring changes in the pyrene monomer/excimer peaks observed for 2. Solvent-dependent fluorescence changes that were observed for indole (3) and dansyl (4) side-chained SATs in bilayers showed that these residues experienced an environment between epsilon=9 (CH2Cl2) and epsilon=24 (EtOH) in polarity. Fluorescence resonance energy transfer (FRET) between 2 and 3 demonstrated aggregation of SAT monomers within the bilayer. This self-assembly led to pore formation, which was detected as Cl(-) release from the liposomes. The results of acrylamide quenching of fluorescent SATs supported membrane insertion. Studies with NBD-labeled SAT 5 showed that peptide partition into the bilayer is relatively slow. Dithionite quenching of NBD-SATs suggests that the amphiphilic peptides are primarily in the bilayer's outer leaflet. Images obtained by using a fluorescence microscope revealed membrane localization of a fluorescent SAT. Taken together, this study helps define the insertion, membrane localization, and aggregation behavior of this family of synthetic anion transporters in liposomal bilayers.
MeSH term(s)	Anions ; Buffers ; Fluorescence Resonance Energy Transfer/methods ; Fluorescent Dyes/chemical synthesis ; Lipid Bilayers/chemistry ; Liposomes/chemistry ; Membrane Transport Proteins/chemistry ; Peptides/chemistry ; Phospholipids/chemistry ; Time Factors ; Water/chemistry
Chemical Substances	Anions ; Buffers ; Fluorescent Dyes ; Lipid Bilayers ; Liposomes ; Membrane Transport Proteins ; Peptides ; Phospholipids ; Water (059QF0KO0R)
Language	English
Publishing date	2008-05-15
Publishing country	Germany
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	1478547-X
ISSN	1521-3765 ; 0947-6539
ISSN (online)	1521-3765
ISSN	0947-6539
DOI	10.1002/chem.200800147
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