101
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Ionic transport across tailored nanoporous anodic alumina membranes. J Colloid Interface Sci 2012; 376:40-6. [DOI: 10.1016/j.jcis.2012.02.066] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 02/22/2012] [Accepted: 02/27/2012] [Indexed: 11/23/2022]
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102
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ACHAR HVBALACHANDRA, BHATTACHARYA ENAKSHI. NANOPOROUS SILICON MEMBRANE FOR BIOMOLECULAR SEPARATION. INTERNATIONAL JOURNAL OF NANOSCIENCE 2012. [DOI: 10.1142/s0219581x11008915] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Separation of biomolecules based on their size and charge is an important procedure employed in biomolecular analysis. Nanosieve comprising of a semi-permeable membrane with nanometer-sized pores is used for this purpose. Described here is the fabrication of ultra thin nanoporous silicon membrane, which can be used as nanosieve, making use of standard microelectronics fabrication techniques. Lithography and bulk silicon etching is used to initially create a 10 μm thick sacrificial membrane in the center of a 200 μm thick silicon substrate. A three-layer stack of SiO2 , amorphous silicon ( a-Si ) and SiO2 is then deposited using chemical vapor deposition technique. The sample is subjected to rapid thermal annealing during which pores are formed in the a-Si layer. Finally, the 15 nm thick nanoporous silicon membrane is released using reactive ion etching of the sacrificial membrane. The formation of the pores is confirmed by transmission and scanning electron microscope images. At present the pore formation is random; our future work will focus on controlled nucleation of silicon nanocrystals so as to get pores at desired locations.
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Affiliation(s)
- H. V. BALACHANDRA ACHAR
- Microelectronics and MEMS Laboratory, Electrical Engineering Department, Indian Institute of Technology Madras, Chennai 600 036, India
| | - ENAKSHI BHATTACHARYA
- Microelectronics and MEMS Laboratory, Electrical Engineering Department, Indian Institute of Technology Madras, Chennai 600 036, India
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103
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Abstract
Synthetic nanoporous membranes have been used in numerous biosensing applications, such as glucose detection, nucleic acid detection, bacteria detection, and cell-based sensing. The increased surface affinity area and enhanced output sensing signals make the nanoporous membranes increasingly attractive as biosensing platforms. Surface modification techniques can be used to improve surface properties for realizable bioanalyte immobilization, conjugation, and detection. Combined with realizable detection techniques such as electrochemical and optical detection methods, nanoporous membrane–based biosensors have advantages, including rapid response, high sensitivity, and low cost. In this paper, an overview of nanoporous membranes for biosensing application is given. Types of nanoporous membranes including polymer membranes, inorganic membranes, membranes with nanopores fabricated using nanolithography, and nanotube-based membranes are introduced. The fabrication techniques of nanoporous membranes are also discussed. The key requirements of nanoporous membranes for biosensing applications include surface functionality for bioanalyte immobilization, biocompatibility, mechanical and chemical stability, and anti-biofouling capability. The recent advances and development of nanoporous membrane–based biosensors are discussed, especially for the sensing mechanism and surface functionalization strategies. Finally, the challenges and future development of nanoporous membrane for biosensing applications are discussed.
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Affiliation(s)
- YANG MO
- Department of Health Technology and Informatics, Biomedical Engineering Programme, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - TAN FEI
- Department of Health Technology and Informatics, Biomedical Engineering Programme, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
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104
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Naveed H, Jimenez-Morales D, Tian J, Pasupuleti V, Kenney LJ, Liang J. Engineered oligomerization state of OmpF protein through computational design decouples oligomer dissociation from unfolding. J Mol Biol 2012; 419:89-101. [PMID: 22391420 DOI: 10.1016/j.jmb.2012.02.043] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 02/24/2012] [Accepted: 02/25/2012] [Indexed: 12/14/2022]
Abstract
Biogenesis of β-barrel membrane proteins is a complex, multistep, and as yet incompletely characterized process. The bacterial porin family is perhaps the best-studied protein family among β-barrel membrane proteins that allows diffusion of small solutes across the bacterial outer membrane. In this study, we have identified residues that contribute significantly to the protein-protein interaction (PPI) interface between the chains of outer membrane protein F (OmpF), a trimeric porin, using an empirical energy function in conjunction with an evolutionary analysis. By replacing these residues through site-directed mutagenesis either with energetically favorable residues or substitutions that do not occur in natural bacterial outer membrane proteins, we succeeded in engineering OmpF mutants with dimeric and monomeric oligomerization states instead of a trimeric oligomerization state. Moreover, our results suggest that the oligomerization of OmpF proceeds through a series of interactions involving two distinct regions of the extensive PPI interface: two monomers interact to form a dimer through the PPI interface near G19. This dimer then interacts with another monomer through the PPI interface near G135 to form a trimer. We have found that perturbing the PPI interface near G19 results in the formation of the monomeric OmpF only. Thermal denaturation of the designed dimeric OmpF mutant suggests that oligomer dissociation can be separated from the process of protein unfolding. Furthermore, the conserved site near G57 and G59 is important for the PPI interface and might provide the essential scaffold for PPIs.
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Affiliation(s)
- Hammad Naveed
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
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105
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Jain HV, Moldovan NI, Byrne HM. Modeling stem/progenitor cell-induced neovascularization and oxygenation around solid implants. Tissue Eng Part C Methods 2012; 18:487-95. [PMID: 22224628 DOI: 10.1089/ten.tec.2011.0452] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tissue engineering constructs and other solid implants with biomedical applications, such as drug delivery devices or bioartificial organs, need oxygen (O(2)) to function properly. To understand better the vascular integration of such devices, we recently developed a novel model sensor containing O(2)-sensitive crystals, consisting of a polymeric capsule limited by a nanoporous filter. The sensor was implanted in mice with hydrogel alone (control) or hydrogel embedded with mouse CD117/c-kit+ bone marrow progenitor cells in order to stimulate peri-implant neovascularization. The sensor provided local partial O(2) pressure (pO(2)) using noninvasive electron paramagnetic resonance signal measurements. A consistently higher level of peri-implant oxygenation was observed in the cell-treatment case than in the control over a 10-week period. To provide a mechanistic explanation of these experimental observations, we present in this article a mathematical model, formulated as a system of coupled partial differential equations, that simulates peri-implant vascularization. In the control case, vascularization is considered to be the result of a foreign body reaction, while in the cell-treatment case, adipogenesis in response to paracrine stimuli produced by the stem cells is assumed to induce neovascularization. The model is validated by fitting numerical predictions of local pO(2) to measurements from the implanted sensor. The model is then used to investigate further the potential for using stem cell treatment to enhance the vascular integration of biomedical implants. We thus demonstrate how mathematical modeling combined with experimentation can be used to infer how vasculature develops around biomedical implants in control and stem cell-treated cases.
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Affiliation(s)
- Harsh Vardhan Jain
- Mathematical Biosciences Institute, The Ohio State University, Columbus, OH 43210, USA.
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106
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Naveed H, Xu Y, Jackups R, Liang J. Predicting three-dimensional structures of transmembrane domains of β-barrel membrane proteins. J Am Chem Soc 2012; 134:1775-81. [PMID: 22148174 DOI: 10.1021/ja209895m] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
β-Barrel membrane proteins are found in the outer membrane of gram-negative bacteria, mitochondria, and chloroplasts. They are important for pore formation, membrane anchoring, and enzyme activity. These proteins are also often responsible for bacterial virulence. Due to difficulties in experimental structure determination, they are sparsely represented in the protein structure databank. We have developed a computational method for predicting structures of the transmembrane (TM) domains of β-barrel membrane proteins. Based on physical principles, our method can predict structures of the TM domain of β-barrel membrane proteins of novel topology, including those from eukaryotic mitochondria. Our method is based on a model of physical interactions, a discrete conformational state space, an empirical potential function, as well as a model to account for interstrand loop entropy. We are able to construct three-dimensional atomic structure of the TM domains from sequences for a set of 23 nonhomologous proteins (resolution 1.8-3.0 Å). The median rmsd of TM domains containing 75-222 residues between predicted and measured structures is 3.9 Å for main chain atoms. In addition, stability determinants and protein-protein interaction sites can be predicted. Such predictions on eukaryotic mitochondria outer membrane protein Tom40 and VDAC are confirmed by independent mutagenesis and chemical cross-linking studies. These results suggest that our model captures key components of the organization principles of β-barrel membrane protein assembly.
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Affiliation(s)
- Hammad Naveed
- Department of Bioengineering, University of Illinois at Chicago, 835 South Wolcott Avenue, Chicago, Illinois 60607, USA
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107
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108
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Raz SR, Marchesini GR, Bremer MGEG, Colpo P, Garcia CP, Guidetti G, Norde W, Rossi F. Nanopatterned submicron pores as a shield for nonspecific binding in surface plasmon resonance-based sensing. Analyst 2012; 137:5251-9. [DOI: 10.1039/c2an35521c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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109
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Borgmann S, Schulte A, Neugebauer S, Schuhmann W. Amperometric Biosensors. ADVANCES IN ELECTROCHEMICAL SCIENCES AND ENGINEERING 2011. [DOI: 10.1002/9783527644117.ch1] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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110
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Jimenez-Morales D, Liang J. Pattern of amino acid substitutions in transmembrane domains of β-barrel membrane proteins for detecting remote homologs in bacteria and mitochondria. PLoS One 2011; 6:e26400. [PMID: 22069449 PMCID: PMC3206045 DOI: 10.1371/journal.pone.0026400] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 09/26/2011] [Indexed: 12/11/2022] Open
Abstract
-barrel membrane proteins play an important role in controlling the exchange and transport of ions and organic molecules across bacterial and mitochondrial outer membranes. They are also major regulators of apoptosis and are important determinants of bacterial virulence. In contrast to -helical membrane proteins, their evolutionary pattern of residue substitutions has not been quantified, and there are no scoring matrices appropriate for their detection through sequence alignment. Using a Bayesian Monte Carlo estimator, we have calculated the instantaneous substitution rates of transmembrane domains of bacterial -barrel membrane proteins. The scoring matrices constructed from the estimated rates, called bbTM for -barrel Transmembrane Matrices, improve significantly the sensitivity in detecting homologs of -barrel membrane proteins, while avoiding erroneous selection of both soluble proteins and other membrane proteins of similar composition. The estimated evolutionary patterns are general and can detect -barrel membrane proteins very remote from those used for substitution rate estimation. Furthermore, despite the separation of 2–3 billion years since the proto-mitochondrion entered the proto-eukaryotic cell, mitochondria outer membrane proteins in eukaryotes can also be detected accurately using these scoring matrices derived from bacteria. This is consistent with the suggestion that there is no eukaryote-specific signals for translocation. With these matrices, remote homologs of -barrel membrane proteins with known structures can be reliably detected at genome scale, allowing construction of high quality structural models of their transmembrane domains, at the rate of 131 structures per template protein. The scoring matrices will be useful for identification, classification, and functional inference of membrane proteins from genome and metagenome sequencing projects. The estimated substitution pattern will also help to identify key elements important for the structural and functional integrity of -barrel membrane proteins, and will aid in the design of mutagenesis studies.
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Affiliation(s)
- David Jimenez-Morales
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Jie Liang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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111
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Michelmore A, Mierczynska A, Poh Z, Goreham RV, Losic D, Short RD, Vasilev K. Versatile gradients of chemistry, bound ligands and nanoparticles on alumina nanopore arrays. NANOTECHNOLOGY 2011; 22:415601. [PMID: 21914941 DOI: 10.1088/0957-4484/22/41/415601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nanoporous alumina (PA) arrays produced by self-ordering growth, using electrochemical anodization, have been extensively explored for potential applications based upon the unique thermal, mechanical and structural properties, and high surface-to-volume ratio of these materials. However, the potential applications and functionality of these materials may be further extended by molecular-level engineering of the surface of the pore rims. In this paper we present a method for the generation of chemical gradients on the surface of PA arrays based upon plasma co-polymerization of two monomers. We further extend these chemical gradients, which are also gradients of surface charge, to those of bound ligands and number density gradients of nanoparticles. The latter represent a highly exotic new class of materials, comprising aligned PA, capped by gold nanoparticles around the rim of the pores. Gradients of chemistry, ligands and nanoparticles generated by our method retain the porous structure of the substrate, which is important in applications that take advantage of the inherent properties of these materials. This method can be readily extended to other porous materials.
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Affiliation(s)
- Andrew Michelmore
- Mawson Institute, University of South Australia, Mawson Lakes, SA 5095, Adelaide, Australia
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112
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Vázquez MI, Peláez L, Benavente J, López-Romero JM, Rico R, Hierrezuelo J, Guillén E, López-Ramírez MR. Functionalized lipid nanoparticles-cellophane hybrid films for molecular delivery: preparation, physicochemical characterization, and stability. J Pharm Sci 2011; 100:4815-22. [PMID: 21713774 DOI: 10.1002/jps.22688] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 06/05/2011] [Accepted: 06/09/2011] [Indexed: 11/09/2022]
Abstract
Lipid nanoparticles functionalized with the sunscreen 2,4-dihydroxybenzophenone (FLNPs) have been prepared by the ultrasound method and embedded in highly hydrophilic cellophane supports (regenerated cellulose, RC), creating biocompatible hybrid films (RC-FLNPs samples). The morphology of the FLNPs was studied with transmission microscopy, whereas the surface and interior chemical composition was analyzed by micro-Raman spectroscopy. RC-FLNPs hybrid films were prepared from the immersion of two cellophane supports with different thicknesses and water uptake properties (RC-3 and RC-6) in an aqueous dispersion of FLNPs. The structure of this hybrid material was visualized with bright-field microscopy, which clearly showed the inclusion of the FLNPs in the cellophane matrix. The stability of the RC-FLNPs films with respect to both aqueous environments and time was demonstrated by NaCl diffusion measurements. The reduction in the diffusion coefficient through the nanoparticle-modified films compared with the original supports confirms the presence of nanoparticles for concentration gradients of up to 0.4 M (osmotic pressure around 10 bar), indicating the stability of the hybrid hydrophilic material, even in aqueous environments and under matter flow conditions for a period of 21 days.
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Affiliation(s)
- M Isabel Vázquez
- Dept. de Física Aplicada, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
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113
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Gold-coated magnetic nanoparticles as “dispersible electrodes” – Understanding their electrochemical performance. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2010.12.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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114
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Nanoparticles and microparticles for skin drug delivery. Adv Drug Deliv Rev 2011; 63:470-91. [PMID: 21315122 DOI: 10.1016/j.addr.2011.01.012] [Citation(s) in RCA: 459] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 01/27/2011] [Accepted: 01/31/2011] [Indexed: 01/29/2023]
Abstract
Skin is a widely used route of delivery for local and systemic drugs and is potentially a route for their delivery as nanoparticles. The skin provides a natural physical barrier against particle penetration, but there are opportunities to deliver therapeutic nanoparticles, especially in diseased skin and to the openings of hair follicles. Whilst nanoparticle drug delivery has been touted as an enabling technology, its potential in treating local skin and systemic diseases has yet to be realised. Most drug delivery particle technologies are based on lipid carriers, i.e. solid lipid nanoparticles and nanoemulsions of around 300 nm in diameter, which are now considered microparticles. Metal nanoparticles are now recognized for seemingly small drug-like characteristics, i.e. antimicrobial activity and skin cancer prevention. We present our unpublished clinical data on nanoparticle penetration and previously published reports that support the hypothesis that nanoparticles >10nm in diameter are unlikely to penetrate through the stratum corneum into viable human skin but will accumulate in the hair follicle openings, especially after massage. However, significant uptake does occur after damage and in certain diseased skin. Current chemistry limits both atom by atom construction of complex particulates and delineating their molecular interactions within biological systems. In this review we discuss the skin as a nanoparticle barrier, recent work in the field of nanoparticle drug delivery to the skin, and future directions currently being explored.
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115
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Saito A, Sawada K, Fujimura S. Present status and future perspectives on the development of bioartificial kidneys for the treatment of acute and chronic renal failure patients. Hemodial Int 2011; 15:183-92. [PMID: 21395969 DOI: 10.1111/j.1542-4758.2011.00530.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A bioartificial renal tubule device (BTD) consisting of a hollow-fiber module and human proximal tubular epithelial cells has been completed technically by Humes and colleagues and a few other groups. Humes and colleagues developed BTD, treated acute kidney injury patients with multiorgan failure by continuous hemofiltration (CHF) in conjunction with BTD, and reported a significantly higher survival rate than that by CHF with BTD without cells in the Food and Drug Administration phase IIa trial. However, BTD has never been approved by the US Government, as the CHF+BTD treatment did not show a significant difference from the control group in the phase IIb trial. Human proximal tubular epithelial cells were confirmed to be overgrown on artificial membrane, which resulted in the inhibition of active transports and the metabolism of essential substances. Function of the BTD could be maintained in a U0126-contained medium, even if the BTD had to have been waited by a new acute kidney injury patient for several weeks. For wearable kidneys, heparin-covalently bound membrane or methacryloyloxyethyl phosphorylcholine (MPC) polymer-coated membranes are candidates for antithrombogenic hemofilters, while endothelial progenitor cells from a cord blood, CD133(+) cells-attached hemofilter in which the permeability of the cells was enhanced by the enlarged diameter of fenestrae by treating with cytochalasin B are another candidate. The MPC blend membrane containing 1% of the MPC polymer in polysulfone was developed as a BTD module. MPC was 7 times larger at the sponge layer than at the skin layer of the membrane, resulting in hemocompatibility at the sponge layer and cytocompatibility at the skin layer.
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Affiliation(s)
- Akira Saito
- Department of Medicine, Division of Nephrology and Metabolism, Tokai University School of Medicine, Isehara, Japan.
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116
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Biotechnical and other applications of nanoporous membranes. Trends Biotechnol 2011; 29:259-66. [PMID: 21388697 DOI: 10.1016/j.tibtech.2011.02.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 01/19/2011] [Accepted: 02/01/2011] [Indexed: 11/21/2022]
Abstract
Recent advances mean that arrays of nearly uniform cylindrical, conical and pyramidal shaped pores can be produced in several types of substrates. Surface modification of nanopore surfaces can give unique mass transport characteristics that have recently been explored for biomolecule separation, detection and purification. Recent interest has focused on the use of nanoporous membranes for mass transfer diodes that act analogous to solid-state devices based on electron conduction. Asymmetric pores such as conical pores can show superior performance characteristics compared to traditional cylindrical pores in ion rectification. However, many phenomena for membranes with asymmetric pores still remain to be exploited in biomolecular separation, biosensing, microfluidics, logic gates, and energy harvesting and storage.
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117
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Bhattacharya J, Kisner A, Offenhäusser A, Wolfrum B. Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2011; 2:104-109. [PMID: 21977420 PMCID: PMC3148057 DOI: 10.3762/bjnano.2.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 02/04/2011] [Indexed: 05/31/2023]
Abstract
Solid state nanoporous membranes show great potential as support structures for biointerfaces. In this paper, we present a technique for fabricating nanoporous alumina membranes under constant-flow conditions in a microfluidic environment. This approach allows the direct integration of the fabrication process into a microfluidic setup for performing biological experiments without the need to transfer the brittle nanoporous material. We demonstrate this technique by using the same microfluidic system for membrane fabrication and subsequent liposome fusion onto the nanoporous support structure. The resulting bilayer formation is monitored by impedance spectroscopy across the nanoporous alumina membrane in real-time. Our approach offers a simple and efficient methodology to investigate the activity of transmembrane proteins or ion diffusion across membrane bilayers.
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Affiliation(s)
- Jaydeep Bhattacharya
- Peter Grünberg Institute, PGI-8/ICS-8, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425 Jülich, Germany and Jülich - Aachen Research Alliance (JARA - FIT), Germany
| | - Alexandre Kisner
- Peter Grünberg Institute, PGI-8/ICS-8, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425 Jülich, Germany and Jülich - Aachen Research Alliance (JARA - FIT), Germany
| | - Andreas Offenhäusser
- Peter Grünberg Institute, PGI-8/ICS-8, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425 Jülich, Germany and Jülich - Aachen Research Alliance (JARA - FIT), Germany
| | - Bernhard Wolfrum
- Peter Grünberg Institute, PGI-8/ICS-8, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425 Jülich, Germany and Jülich - Aachen Research Alliance (JARA - FIT), Germany
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118
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Prasad PV, Pal PC, Rao DN, Shrivastav TG, Ge RS. Bird’s Eye View on the Recent Advances in Drug Delivery Systems. ACTA ACUST UNITED AC 2011. [DOI: 10.4236/jbnb.2011.225065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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119
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Yang Q, Adrus N, Tomicki F, Ulbricht M. Composites of functional polymeric hydrogels and porous membranes. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm02234a] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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120
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Choi CK, Fowlkes JD, Retterer ST, Siuti P, Iyer S, Doktycz MJ. Surface charge- and space-dependent transport of proteins in crowded environments of nanotailored posts. ACS NANO 2010; 4:3345-55. [PMID: 20515056 PMCID: PMC2892340 DOI: 10.1021/nn901831q] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The reaction and diffusion of molecules across barriers and through crowded environments is integral to biological system function and to separation technologies. Ordered, microfabricated post arrays are a promising route to creating synthetic barriers with controlled chemical and physical characteristics. They can be used to create crowded environments, to mimic aspects of cellular membranes, and to serve as engineered replacements of polymer-based separation media. Here, the translational diffusion of fluorescein isothiocyante and various forms of green fluorescent protein (GFP), including "supercharged" variants, are examined in a silicon-based post array environment. The technique of fluorescence recovery after photobleaching (FRAP) is combined with analytical approximations and numerical simulations to assess the relative effects of reaction and diffusion on molecular transport, respectively. FRAP experiments were conducted for 64 different cases where the molecular species, the density of the posts, and the chemical surface charge of the posts were varied. In all cases, the dense packing of the posts hindered the diffusive transport of the fluorescent species. The supercharged GFPs strongly interacted with oppositely charged surfaces. With similar molecular and surface charges, transport is primarily limited by hindered diffusion. For conventional, enhanced GFP in a positively charged surface environment, transport was limited by the coupled action of hindered diffusion and surface interaction with the posts. Quantification of the size-, space-, time-, and charge-dependent translational diffusion in the post array environments can provide insight into natural processes and guide the design and development of selective membrane systems.
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Affiliation(s)
- Chang Kyoung Choi
- Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI 49931-1295
| | - Jason D. Fowlkes
- Center for Nanoscale Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - Scott T. Retterer
- Center for Nanoscale Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - Piro Siuti
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Graduate Program in Genome Science and Technology, University of Tennessee, Knoxville, TN 37996
| | - Sukanya Iyer
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Graduate Program in Genome Science and Technology, University of Tennessee, Knoxville, TN 37996
| | - Mitchel J. Doktycz
- Center for Nanoscale Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Graduate Program in Genome Science and Technology, University of Tennessee, Knoxville, TN 37996
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121
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Bernards DA, Desai TA. Nanoscale porosity in polymer films: fabrication and therapeutic applications. SOFT MATTER 2010; 6:1621-1631. [PMID: 22140398 PMCID: PMC3226808 DOI: 10.1039/b922303g] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This review focuses on current developments in the field of nanostructured bulk polymers and their application in bioengineering and therapeutic sciences. In contrast to well-established nanoscale materials, such as nanoparticles and nanofibers, bulk nanostructured polymers combine nanoscale structure in a macroscopic construct, which enables unique application of these materials. Contemporary fabrication and processing techniques capable of producing nanoporous polymer films are reviewed. Focus is placed on techniques capable of sub-100 nm features since this range approaches the size scale of biological components, such as proteins and viruses. The attributes of these techniques are compared, with an emphasis on the characteristic advantages and limitations of each method. Finally, application of these materials to biofiltration, immunoisolation, and drug delivery are reviewed.
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Affiliation(s)
- Daniel A. Bernards
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
| | - Tejal A. Desai
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
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