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Mohan P, Noonan PS, Nakatsuka MA, Goodwin AP. On-demand droplet fusion: a strategy for stimulus-responsive biosensing in solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12321-7. [PMID: 25263344 PMCID: PMC4204924 DOI: 10.1021/la502483u] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A novel strategy is reported for biochemically controlled fusion of oil-in-water (O/W) droplets as an in-solution sensor for biological targets. Inspired by the SNARE complex in cells, the emulsions were stabilized by a combination of phospholipids, phospholipid-poly(ethylene glycol) conjugates, and cholesterol-anchored oligonucleotides. Prior to oligonucleotide binding, the droplets were stable in aqueous media, but hybridization of the oligonucleotides in a zipperlike fashion was shown to initiate droplet fusion. Using image analysis of content mixing of dye-loaded droplets, fusion specificity was studied and optimized as a function of interfacial chemistry. Changing the orientation of the anchored oligonucleotides, using long-chain phospholipids (C18 and C22), and binding a complementary oligonucleotide slowed or even halted fusion completely. Based on these studies, a sensor for the biomarker thrombin was designed using competitive binding of aptamer strands, with droplet fusion increasing as a function of thrombin addition in accordance with a simple binding model, with sensitivity down to 100 nM and with results in as little as 15 min. Future efforts will focus on utilizing this mechanism of content mixing to facilitate highly sensitive detection via modalities such as magnetoresistance or chemiluminescence.
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Wang X, Yu B, Ren W, Mo X, Zhou C, He H, Jia H, Wang L, Jacob ST, Lee RJ, Ghoshal K, Lee LJ. Enhanced hepatic delivery of siRNA and microRNA using oleic acid based lipid nanoparticle formulations. J Control Release 2013; 172:690-8. [PMID: 24121065 PMCID: PMC4307782 DOI: 10.1016/j.jconrel.2013.09.027] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 08/26/2013] [Accepted: 09/25/2013] [Indexed: 01/15/2023]
Abstract
Many cationic lipids have been developed for lipid-based nanoparticles (LNPs) for delivery of siRNA and microRNA (miRNA). However, less attention has been paid to "helper lipids". Here, we investigated several "helper lipids" and examined their effects on the physicochemical properties such as particle size and zeta potential, as well as cellular uptake and transfection efficiency. We found that inclusion of oleic acid (OA), an unsaturated fatty acid, into the LNP formulation significantly enhanced the delivery efficacy for siRNA and miRNA. For proof-of-concept, miR-122, a liver-specific microRNA associated with many liver diseases, was used as a model agent to demonstrate the hepatic delivery efficacy both in tumor cells and in animals. Compared to Lipofectamine 2000, a commercial transfection agent, LNPs containing OA delivered microRNA-122 in a more efficient manner with a 1.8-fold increase in mature miR-122 expression and a 20% decrease in Bcl-w, a target of microRNA-122. In comparison with Invivofectamine, a commercial transfection agent specifically designed for hepatic delivery, LNPs containing OA showed comparable liver accumulation and in vivo delivery efficiency. These findings demonstrated the importance of "helper lipid" components of the LNP formulation on the cellular uptake and transfection activity of siRNA and miRNA. LNPs containing OA is a promising nanocarrier system for the delivery of RNA-based therapeutics in liver diseases.
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Affiliation(s)
- Xinmei Wang
- NSF Nanoscale Science and Engineering Center (NSEC), The Ohio State University, Columbus, OH, U.S.A
| | - Bo Yu
- NSF Nanoscale Science and Engineering Center (NSEC), The Ohio State University, Columbus, OH, U.S.A
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH, U.S.A
| | - Wei Ren
- Department of Physiology, The Ohio State University, Columbus, OH, U.S.A
| | - Xiaokui Mo
- Center for Biostatistics, The Ohio State University, Columbus, OH, U.S.A
| | - Chenguang Zhou
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH, U.S.A
| | - Hongyan He
- NSF Nanoscale Science and Engineering Center (NSEC), The Ohio State University, Columbus, OH, U.S.A
| | - HuLiang Jia
- Liver Cancer Institute and Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lu Wang
- Liver Cancer Institute and Zhongshan Hospital, Fudan University, Shanghai, China
| | - Samson T. Jacob
- Molecular, Cellular, and Developmental Biology Program, The Ohio State University, Columbus, OH, U.S.A
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, U.S.A
| | - Robert J. Lee
- NSF Nanoscale Science and Engineering Center (NSEC), The Ohio State University, Columbus, OH, U.S.A
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH, U.S.A
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, U.S.A
| | - Kalpana Ghoshal
- Molecular, Cellular, and Developmental Biology Program, The Ohio State University, Columbus, OH, U.S.A
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, U.S.A
- Department of Pathology, The Ohio State University, Columbus, OH, U.S.A
| | - L. James Lee
- NSF Nanoscale Science and Engineering Center (NSEC), The Ohio State University, Columbus, OH, U.S.A
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH, U.S.A
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH, U.S.A
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Szule JA, Coorssen JR. Revisiting the role of SNAREs in exocytosis and membrane fusion. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1641:121-35. [PMID: 12914953 DOI: 10.1016/s0167-4889(03)00095-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
For over a decade SNARE hypotheses have been proposed to explain the mechanism of membrane fusion, yet the field still lacks sufficient evidence to conclusively identify the minimal components of native fusion. Consequently, debate concerning the postulated role(s) of SNAREs in membrane fusion continues. The focus of this review is to revisit original literature with a current perspective. Our analysis begins with the earliest studies of clostridial toxins, leading to various cellular and molecular approaches that have been used to test for the roles of SNAREs in exocytosis. We place much emphasis on distinguishing between specific effects on membrane fusion and effects on other critical steps in exocytosis. Although many systems can be used to study exocytosis, few permit selective access to specific steps in the pathway, such as membrane fusion. Thus, while SNARE proteins are essential to the physiology of exocytosis, assay limitations often prevent definitive conclusions concerning the molecular mechanism of membrane fusion. In all, the SNAREs are more likely to function upstream as modulators or priming factors of fusion.
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Affiliation(s)
- Joseph A Szule
- Cellular and Molecular Neurobiology Research Group, Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
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Agirre A, Barco A, Carrasco L, Nieva JL. Viroporin-mediated membrane permeabilization. Pore formation by nonstructural poliovirus 2B protein. J Biol Chem 2002; 277:40434-41. [PMID: 12183456 DOI: 10.1074/jbc.m205393200] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enterovirus nonstructural 2B protein is involved in cell membrane permeabilization during late viral infection. Here we analyze the pore forming activity of poliovirus 2B and several of its variants. Solubilization of 2B protein was achieved by generating a fusion protein comprised of poliovirus 2B attached to a maltose-binding protein (MBP) as an N-terminal solubilization partner. MBP-2B was assayed using large unilamellar vesicles as target membranes. This fusion protein was able to assemble into discrete structures that disrupted the permeability barrier of vesicles composed of anionic phospholipids. The transbilayer aqueous connections generated by MBP-2B were stable over time, allowing the passage of solutes of molecular mass under 1,000 Da. Oligomerization was investigated using fluorescence resonance energy transfer. Our data indicate that MBP-2B aggregation occurs at the membrane surface. Moreover, MBP-2B binding to membranes promoted the formation of SDS-resistant tetramers. We conclude that MBP-2B forms oligomers capable of generating a tetrameric aqueous pore in lipid bilayers. These findings are the first evidence of viroporin activity shown by a protein from a naked animal virus.
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Affiliation(s)
- Aitziber Agirre
- Unidad de Biofisica Centro Superior de Investigaciones Cientificas, Departamento de Bioquímica, Universidad del Pais Vasco, Apartado 644, 48080 Bilbao, Spain
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Coorssen JR, Blank PS, Albertorio F, Bezrukov L, Kolosova I, Backlund PS, Zimmerberg J. Quantitative femto- to attomole immunodetection of regulated secretory vesicle proteins critical to exocytosis. Anal Biochem 2002; 307:54-62. [PMID: 12137779 DOI: 10.1016/s0003-2697(02)00015-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Although immunoblotting (Western blotting) is widely used for the detection of specific proteins, it is often thought to be an inadequate technique for accurate and precise measurements of protein concentration. However, an accurate and precise technique is essential for quantitative testing of hypotheses, and thus for the analysis and understanding of proposed molecular mechanisms. The analysis of Ca(2+)-triggered exocytosis, the ubiquitous eukaryotic process by which vesicles fuse to the plasma membrane and release their contents, requires such an unambiguous identification and a quantitative assessment of the membrane surface density of specific molecules. Newly refined immunoblotting and analysis approaches permit a quantitative analysis of the SNARE protein complement (VAMP, SNAP-25, and syntaxin) of functional secretory vesicles. The method illustrates the feasibility of the routine quantification of femtomole to attomole amounts of known proteins by immunoblotting. The results indicate that sea urchin egg secretory vesicles and synaptic vesicles have markedly similar SNARE densities.
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Affiliation(s)
- Jens R Coorssen
- Laboratory of Cellular and Molecular Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA.
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