701
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Abstract
Life is a mechanical process. Cells, tissues, and bodies must act within their environments to grow, divide, move, communicate, and defend themselves. The stiffness and viscosity of cells and biologic materials will vary depending upon a wide variety of variables including for example environmental conditions, activation of signaling pathways, stage of development, gene expression. By pushing and pulling cells or materials such as mucus or extracellular matrix, one can learn about their mechanical properties. By varying the conditions, signaling pathways or genetic background, one can also assess how the response of the cell or material is modulated by that pathway. Magnetic particles are available commercially in many useful sizes, magnetic contents, and surface chemistries. The variety of surface chemistries allow forces to be applied to a specimen through specific linkages such as receptors or particular proteins, allowing the biologist to ask fundamental questions about the role of those linkages in the transduction of force or motion. In this chapter, we discuss the use of a magnetic system designed to apply a wide range of forces and force patterns fully integrated into a high numerical aperture inverted fluorescence microscope. Fine, thin and flat magnetic poles allow the use of high magnification microscope objectives, and flexible software to control the direction and pattern of applied forces supports a variety of experimental situations. The system can be coupled with simple video acquisition for medium-bandwidth, two-dimensional particle tracking. Alternatively, the system can be coupled with a laser tracking and position feedback system for higher resolution, high bandwidth, three-dimensional tracking.
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702
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Thierry B, Al-Ejeh F, Brown MP, Majewski P, Griesser HJ. Immunotargeting of Functional Nanoparticles for MRI detection of Apoptotic Tumor Cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2009; 21:541-5. [PMID: 21161977 DOI: 10.1002/adma.200800998] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Affiliation(s)
- Benjamin Thierry
- Ian Wark Research Institute, University of South Australia SA 5095 (Australia)
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703
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704
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Lai SK, Wang YY, Cone R, Wirtz D, Hanes J. Altering mucus rheology to "solidify" human mucus at the nanoscale. PLoS One 2009; 4:e4294. [PMID: 19173002 PMCID: PMC2627937 DOI: 10.1371/journal.pone.0004294] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 12/11/2008] [Indexed: 11/25/2022] Open
Abstract
The ability of mucus to function as a protective barrier at mucosal surfaces rests on its viscous and elastic properties, which are not well understood at length scales relevant to pathogens and ultrafine environmental particles. Here we report that fresh, undiluted human cervicovaginal mucus (CVM) transitions from an impermeable elastic barrier to non-adhesive objects sized 1 microm and larger to a highly permeable viscoelastic liquid to non-adhesive objects smaller than 500 nm in diameter. Addition of a nonionic detergent, present in vaginal gels, lubricants and condoms, caused CVM to behave as an impermeable elastic barrier to 200 and 500 nm particles, suggesting that the dissociation of hydrophobically-bundled mucin fibers created a finer elastic mucin mesh. Surprisingly, the macroscopic viscoelasticity, which is critical to proper mucus function, was unchanged. These findings provide important insight into the nanoscale structural and barrier properties of mucus, and how the penetration of foreign particles across mucus might be inhibited.
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Affiliation(s)
- Samuel K. Lai
- Department of Chemical & Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Ying-Ying Wang
- Department of Biomedical Engineering, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Richard Cone
- Department of Biophysics, The Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Denis Wirtz
- Department of Chemical & Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Justin Hanes
- Department of Chemical & Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Biomedical Engineering, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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705
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Suk JS, Lai SK, Wang YY, Ensign LM, Zeitlin PL, Boyle MP, Hanes J. The penetration of fresh undiluted sputum expectorated by cystic fibrosis patients by non-adhesive polymer nanoparticles. Biomaterials 2009; 30:2591-7. [PMID: 19176245 DOI: 10.1016/j.biomaterials.2008.12.076] [Citation(s) in RCA: 242] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 12/31/2008] [Indexed: 02/04/2023]
Abstract
Highly viscoelastic and adhesive sputum has precluded efficient nanoparticle-based drug and gene delivery to the lungs of patients with cystic fibrosis (CF). We sought to determine whether nanoparticles coated with non-mucoadhesive polymers could penetrate CF sputum, and to use these "muco-inert particles" (MIPs) as non-destructive nanoprobes to characterize the sputum microstructure. Particles as large as 200 nm in diameter that were densely coated with low MW polyethylene glycol (PEG) moved through undiluted CF sputum with average speeds up to 90-fold faster than similarly-sized uncoated particles. On the other hand, the transport of both coated and uncoated 500 nm particles was strongly hindered. The local viscosity of sputum, encountered by the fastest 10% of 200 nm MIPs, was only 5-fold higher than that of water, whereas the bulk viscosity was 10,000-fold higher at low shear rates. Using measured transport rates of various sized MIPs combined with an obstruction-scaling model, we determined that the average 3D mesh spacing of CF sputum is approximately 140+/-50 nm (range: 60-300 nm). Taken together, these results demonstrate that nanoparticles up to 200 nm in diameter that do not adhere to CF sputum can move rapidly through this critical barrier by accessing pores that are filled with a low viscosity fluid. The results also offer hope that desperately needed sputum-penetrating drug- and gene-carrier nanoparticles can be developed for CF.
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Affiliation(s)
- Jung Soo Suk
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA
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706
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Wang YY, Lai SK, Suk JS, Pace A, Cone R, Hanes J. Addressing the PEG mucoadhesivity paradox to engineer nanoparticles that "slip" through the human mucus barrier. Angew Chem Int Ed Engl 2008; 47:9726-9. [PMID: 18979480 DOI: 10.1002/anie.200803526] [Citation(s) in RCA: 427] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ying-Ying Wang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
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707
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Occhipinti P, Griffiths PC. Quantifying diffusion in mucosal systems by pulsed-gradient spin-echo NMR. Adv Drug Deliv Rev 2008; 60:1570-82. [PMID: 18940211 DOI: 10.1016/j.addr.2008.08.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 08/28/2008] [Indexed: 01/22/2023]
Abstract
Mucus, a thick and slimy secretion produced by submucosal cells, covers many epithelial surfaces in mammalian organs and prevents foreign particles that enter the body from accessing cells. However, the mucus layer also represents a potential barrier to the efficient delivery of nano-sized drug delivery systems (polyplexes, lipoplexes, particles) to the underlying mucosal epithelium. Many studies have considered the ability of nano-sized particles and polymers to diffuse within the mucosal network using a range of different techniques, including multiple-particle tracking (MPT), diffusion chamber studies and fluorescence recovery after photobleaching (FRAP). This review highlights the current understanding of the interaction of the diffusion of nano-sized structures within mucosal networks. Moreover, this article presents an introduction to pulsed-gradient spin-echo NMR (PGSE-NMR), a potential new tool to investigate the mobility of molecular species through mucosal networks and related biological gels.
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Affiliation(s)
- Paola Occhipinti
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
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708
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Wang YY, Lai S, Suk J, Pace A, Cone R, Hanes J. Addressing the PEG Mucoadhesivity Paradox to Engineer Nanoparticles that “Slip” through the Human Mucus Barrier. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200803526] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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709
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Real-time multiple particle tracking of gene nanocarriers in complex biological environments. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2008. [PMID: 18470640 DOI: 10.1007/978-1-60327-248-3_6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Complex biological fluids, such as the vast and molecularly crowded cell cytoplasm and the highly viscoelastic mucus that protects many entry ways to the body, pose significant barriers to efficient gene delivery. Understanding the dynamics of gene carriers in such environments allows insight that leads to rational improvements in gene vector design. Fluorescence techniques that provide only ensemble-averaged transport characteristics do not provide detailed information related to the nature of various barriers to efficient gene vector transport to target cell nuclei. Multiple particle tracking (MPT) allows the tracking of the real-time motion of up to hundreds of individual particles simultaneously with high temporal and spatial resolution. We have adapted MPT to study gene carrier transport in live cells and in fresh, undiluted human mucus. By analyzing the displacements of gene vectors as a function of time scale, this technique provides, on a per particle basis, highly quantitative measurements of the transport rates and transport mechanisms, as well as biophysical information of the complex biological environments. Combining MPT with confocal microscopy (confocal particle tracking) allows dynamic and quantitative co-localization determination of gene carriers with various cellular structures, such as endosomes, lysosomes, the endoplasmic reticulum, and Golgi. We have applied MPT to enhance understanding of critical extracellular and intracellular bottlenecks to gene transfer.
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710
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Thierry B, Zimmer L, McNiven S, Finnie K, Barbé C, Griesser HJ. Electrostatic self-assembly of PEG copolymers onto porous silica nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:8143-8150. [PMID: 18590299 DOI: 10.1021/la8007206] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A critical requirement toward the clinical use of nanocarriers in drug delivery applications is the development of optimal biointerfacial engineering procedures designed to resist biologically nonspecific adsorption events. Minimization of opsonization increases blood residence time and improves the ability to target solid tumors. We report the electrostatic self-assembly of polyethyleneimine-polyethylene glycol (PEI-PEG) copolymers onto porous silica nanoparticles. PEI-PEG copolymers were synthesized and their adsorption by self-assembly onto silica surfaces were investigated to achieve a better understanding of structure-activity relationships. Quartz-crystal microbalance (QCM) study confirmed the rapid and stable adsorption of the copolymers onto silica-coated QCM sensors driven by strong electrostatic interactions. XPS and FT-IR spectroscopy were used to analyze the coated surfaces, which indicated the presence of dense PEG layers on the silica nanoparticles. Dynamic light scattering was used to optimize the coating procedure. Monodisperse dispersions of the PEGylated nanoparticles were obtained in high yields and the thin PEG layers provided excellent colloidal stability. In vitro protein adsorption tests using 5% serum demonstrated the ability of the self-assembled copolymer layers to resist biologically nonspecific fouling and to prevent aggregation of the nanoparticles in physiological environments. These results demonstrate that the electrostatic self-assembly of PEG copolymers onto silica nanoparticles used as drug nanocarriers is a robust and efficient procedure, providing excellent control of their biointerfacial properties.
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Affiliation(s)
- Benjamin Thierry
- Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, Adelaide, South Australia 5095, Australia.
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711
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Chaudhry Q, Scotter M, Blackburn J, Ross B, Boxall A, Castle L, Aitken R, Watkins R. Applications and implications of nanotechnologies for the food sector. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2008; 25:241-58. [DOI: 10.1080/02652030701744538] [Citation(s) in RCA: 503] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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712
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Geonnotti AR, Furlow MJ, Wu T, DeSoto MG, Henderson MH, Kiser PF, Katz DF. Measuring macrodiffusion coefficients in microbicide hydrogels via postphotoactivation scanning. Biomacromolecules 2008; 9:748-51. [PMID: 18193840 DOI: 10.1021/bm701018w] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anthony R Geonnotti
- Department of Biomedical Engineering, Duke University, Box 90281, Durham, North Carolina 27708, USA.
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713
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PEGylation of nanoparticles improves their cytoplasmic transport. Int J Nanomedicine 2007; 2:735-41. [PMID: 18203439 PMCID: PMC2676827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The efficacy of nucleus-targeted drug- or gene-carrying nanoparticles may be limited by slow transport through the molecularly crowded cytoplasm following endosome escape. Cytoskeletal elements and cellular organelles may pose steric and/or adhesive obstacles to the efficient intracellular transport of nanoparticles. To potentially reduce adhesive interactions of colloids with intracellular components, the surface of model nanoparticles was coated with polyethylene glycol (PEG). Subsequently, multiple-particle tracking (MPT) was used to quantify the cytoplasmic transport rates of particles microinjected into the cytoplasm of live cells. PEGylation increased average nanoparticle diffusivities by 100% compared to unPEGylated particles (time scale of 10 s) in live cells. Faster particle transport correlated with a marked decrease in the number of particles that underwent hindered transport, from 79.2% (unmodified) to 48.8% (PEGylated). This result adds to an impressive list of positive benefits associated with PEGylation of drug and gene delivery vectors.
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714
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The Metastatic Stage-dependent Mucosal Expression of Sialic Acid is a Potential Marker for Targeting Colon Cancer with Cationic Polymers. Pharm Res 2007; 25:379-86. [DOI: 10.1007/s11095-007-9330-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Accepted: 04/30/2007] [Indexed: 11/25/2022]
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715
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Lai SK, Hida K, Chen C, Hanes J. Characterization of the intracellular dynamics of a non-degradative pathway accessed by polymer nanoparticles. J Control Release 2007; 125:107-11. [PMID: 18053606 DOI: 10.1016/j.jconrel.2007.10.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 10/05/2007] [Accepted: 10/12/2007] [Indexed: 10/25/2022]
Abstract
Recently, 24 nm polymer nanoparticles were found to access a privileged non-degradative intracellular pathway that leads to perinuclear accumulation. Here, we report the intracellular dynamics of vesicles containing polymer nanoparticles within this non-degradative pathway, characterized by clathrin- and caveolae-independent endocytosis, as compared to endosomes originating from classical clathrin-mediated endocytosis. Similar to transport of acidic endosomes and lysosomes, the dynamic movements of non-degradative vesicles exhibit substantial heterogeneity, including caged diffusion and pearls-on-a-string trajectories, a reflection of microtubule-dependent active transport that leads to rapid accumulation near the cell nucleus. However, the ensemble-averaged intracellular transport rate of vesicles in the non-degradative pathway is 4-fold slower than that of the acidic vesicles of late endosomes and lysosomes, highlighted by a 3-fold smaller fraction of actively transported vesicles. The distinct intracellular dynamics further confirms that small nanoparticles are capable of entering cells via a distinct privileged pathway that does not lead to lysosomal processing. This non-degradative pathway may prove beneficial for the delivery of therapeutics and nucleic acids to the nucleus or nearby organelles.
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Affiliation(s)
- Samuel K Lai
- Department of Chemical & Biomolecular Engineering, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
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716
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Loftsson T, Vogensen SB, Brewster ME, Konrádsdóttir F. Effects of Cyclodextrins on Drug Delivery Through Biological Membranes. J Pharm Sci 2007; 96:2532-46. [PMID: 17630644 DOI: 10.1002/jps.20992] [Citation(s) in RCA: 217] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cyclodextrins have proven themselves to be useful functional excipients. Cyclodextrin derivatives can be hydrophilic or relatively lipophilic based on their substitution and these properties can give insight into their ability to act as permeability enhancers. Lipophilic cyclodextrins such as the methylated derivatives are thought to increase drug flux by altering barrier properties of the membrane through component extraction or fluidization. The hydrophilic cyclodextrin family also modulate drug flux through membranes but via different mechanisms. The current effort seeks to provide various explanations for these observations based on interactions of hydrophilic cyclodextrins with the unstirred water layer that separates the bulk media from biological membranes such as the gastric mucosa, cornea and reproductive tract. Theories on the serial nature of resistances to drug flux are used to explain why hydrophilic cyclodextrins can enhance drug uptake in some situation (i.e., for lipophilic material) but not in others. In addition, the nature of secondary equilibria and competition between cyclodextrins and rheologically important biopolymers such as mucin are assessed to give a complete picture of the effect of these starch derivatives. This information can be useful not only in understanding the actions of cyclodextrin but also in expanding their application and uses.
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Affiliation(s)
- Thorsteinn Loftsson
- Faculty of Pharmacy, University of Iceland, Hofsvallagata 53, IS-107 Reykjavik, Iceland.
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