251
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Huang X, Hauptmann N, Appelhans D, Formanek P, Frank S, Kaskel S, Temme A, Voit B. Synthesis of hetero-polymer functionalized nanocarriers by combining surface-initiated ATRP and RAFT polymerization. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:3579-3583. [PMID: 22911545 DOI: 10.1002/smll.201201397] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/11/2012] [Indexed: 06/01/2023]
Abstract
Smart nanocarriers are created based on a bi-functional hetero-initiator for RAFT and ATRP technique, bi-functionalizing mesoporous silica nanoparticles with two polymer types. The pH-dependent behavior of PDEAEMA as the gatekeeper polymer is verified by electrokinetic measurements and a controlled release behavior is demonstrated using doxorubicin as the drug.
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Affiliation(s)
- Xin Huang
- Leibniz Institute of Polymer Research Dresden, Dresden, Germany
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252
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Xue M, Cao D, Stoddart JF, Zink JI. Size-selective pH-operated megagates on mesoporous silica materials. NANOSCALE 2012; 4:7569-7574. [PMID: 23108219 PMCID: PMC3884833 DOI: 10.1039/c2nr32170j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
pH-responsive megagates have been fabricated around mesoporous silica material SBA-15 in order to mechanize the mesopores. These megagates remain closed in neutral conditions, but open at pH 5. The capping components of the megagates were designed to be capable of controlling pores up to 6.5 nm in diameter. Selectivity of payloads with different sizes can be achieved through the use of different capping components. The operation of the megagates was demonstrated by time-resolved fluorescence spectroscopy which is capable of monitoring the release of both the payload and the cap. This study opens up new possibilities in the field of controllable release.
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Affiliation(s)
- Min Xue
- Department of Chemistry and Biochemistry, and California Nano Systems Institute, University of California, Los Angeles, CA 90095, USA
| | - Dennis Cao
- Center for the Chemistry of Integrated Systems, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA. ; Fax: +1 847-491-1009
- NanoCentury KAIST Institute and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - J. Fraser Stoddart
- Center for the Chemistry of Integrated Systems, Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA. ; Fax: +1 847-491-1009
- NanoCentury KAIST Institute and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Jeffrey I. Zink
- Department of Chemistry and Biochemistry, and California Nano Systems Institute, University of California, Los Angeles, CA 90095, USA
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253
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Candel I, Aznar E, Mondragón L, de la Torre C, Martínez-Máñez R, Sancenón F, Marcos MD, Amorós P, Guillem C, Pérez-Payá E, Costero A, Gil S, Parra M. Amidase-responsive controlled release of antitumoral drug into intracellular media using gluconamide-capped mesoporous silica nanoparticles. NANOSCALE 2012; 4:7237-7245. [PMID: 23072883 DOI: 10.1039/c2nr32062b] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
MCM-41 silica nanoparticles were used as inorganic scaffolding to prepare a nanoscopic-capped hybrid material S1, which was able to release an entrapped cargo in the presence of certain enzymes, whereas in the absence of enzymes, a zero release system was obtained. S1 was prepared by loading nanoparticles with Safranine O dye and was then capped with a gluconamide derivative. In the absence of enzymes, the release of the dye from the aqueous suspensions of S1 was inhibited as a result of the steric hindrance imposed by the bulky gluconamide derivative, the polymerized gluconamide layer and the formation of a dense hydrogen-bonded network around the pore outlets. Upon the addition of amidase and pronase enzymes, delivery of Safranine O dye was observed due to the enzymatic hydrolysis of the amide bond in the anchored gluconamide derivative. S1 nanoparticles were not toxic for cells, as demonstrated by cell viability assays using HeLa and MCF-7 cell lines, and were associated with lysosomes, as shown by confocal microscopy. Finally, the S1–CPT material loaded with the cytotoxic drug camptothecin and capped with the gluconamide derivative was prepared. The HeLa cells treated with S1–CPT underwent cell death as a result of material internalization, and of the subsequent cellular enzyme-mediated hydrolysis and aperture of the molecular gate, which induced the release of the camptothecin cargo.
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Affiliation(s)
- Inmaculada Candel
- Centro de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Unidad Mixta Universitat Politècnica de València-Universitat de València, Spain
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254
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Wang C, Dyar SM, Cao D, Fahrenbach AC, Horwitz N, Colvin MT, Carmieli R, Stern CL, Dey SK, Wasielewski MR, Stoddart JF. Tetrathiafulvalene Hetero Radical Cation Dimerization in a Redox-Active [2]Catenane. J Am Chem Soc 2012; 134:19136-45. [DOI: 10.1021/ja307577t] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Cheng Wang
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
| | - Scott M. Dyar
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- Argonne-Northwestern Solar Energy
Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Dennis Cao
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- NanoCentury KAIST Institute and
Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 37-1 Guseong Dong,
Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Albert C. Fahrenbach
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- NanoCentury KAIST Institute and
Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 37-1 Guseong Dong,
Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Noah Horwitz
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- Argonne-Northwestern Solar Energy
Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michael T. Colvin
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- Argonne-Northwestern Solar Energy
Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Raanan Carmieli
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- Argonne-Northwestern Solar Energy
Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Charlotte L. Stern
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
| | - Sanjeev K. Dey
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
| | - Michael R. Wasielewski
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- Argonne-Northwestern Solar Energy
Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - J. Fraser Stoddart
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- NanoCentury KAIST Institute and
Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 37-1 Guseong Dong,
Yuseong Gu, Daejeon 305-701, Republic of Korea
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255
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Drisko GL, Sanchez C. Hybridization in Materials Science - Evolution, Current State, and Future Aspirations. Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201201216] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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256
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Climent E, Martínez-Máñez R, Maquieira A, Sancenón F, Marcos MD, Brun EM, Soto J, Amorós P. Antibody-capped mesoporous nanoscopic materials: design of a probe for the selective chromo-fluorogenic detection of finasteride. ChemistryOpen 2012; 1:251-9. [PMID: 24551515 PMCID: PMC3922482 DOI: 10.1002/open.201100008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Indexed: 12/25/2022] Open
Abstract
The synthesis of capped mesoporous silica nanoparticles (MSN) conjugated with an antibody (AB) as a gatekeeper has been carried out in order to obtain a delivery system able to release an entrapped cargo (dye) in the presence of a target molecule (antigen) to which the conjugated antibody binds selectively. In particular, MSN loaded with rhodamine B and functionalized on the external surface with a suitable derivative of N-(t-butyl)-3-oxo-(5α,17β)-4-aza-androst-1-ene-17-carboxamide (finasteride) have been prepared (S1). The addition of polyclonal antibodies against finasteride induced capping of the pores due to the interaction with the anchored hapten-like finasteride derivative to give a MSN–hapten–AB nanoparticle S1-AB. It was found that the addition of capped material S1-AB to water solutions containing finasteride resulted in displacement of the antibody, pore uncapping and entrapped-dye release. The response of the gated material is highly selective, and only finasteride, among other steroids, was able to induce a significant uncapping process. Compared with finasteride, the finasteride metabolite was able to release 17 % of the dye, whereas the exogen steroids testosterone, metenolone and 16-β-hydroxystanozolol only induced very little release of rhodamine B (lower than 10 %) from aqueous suspensions containing sensing solid S1-AB. A detection limit as low as 20 ppb was found for the fluorimetric detection of finasteride. In order to evaluate a possible application of the material for label-free detection of finasteride, the capped material was isolated and stored to give final sensing solid S1-AB-i. It was found to display a similar behavior towards finasteride as to that shown by freshly prepared S1-AB; even after a period of two months, no significant loss of selectivity or sensitivity was noted. Moreover, to study the application for the detection of finasteride in biological samples, this “aged” material, S1-AB-i, was tested using commercially available blank urine as matrix. Samples containing 70 and 90 % blank urine were spiked with a defined amount of finasteride, and the concentration was determined using capped S1-AB-i. Recovery ranges from 94 % to 118 % were reached.
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Affiliation(s)
- Estela Climent
- Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain) ; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Campus Rio Ebro 50018 Zaragoza (Spain)
| | - Ramón Martínez-Máñez
- Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain) ; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Campus Rio Ebro 50018 Zaragoza (Spain)
| | - Angel Maquieira
- Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain)
| | - Félix Sancenón
- Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain) ; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Campus Rio Ebro 50018 Zaragoza (Spain)
| | - M Dolores Marcos
- Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain) ; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Campus Rio Ebro 50018 Zaragoza (Spain)
| | - Eva M Brun
- Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain)
| | - Juan Soto
- Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain)
| | - Pedro Amorós
- Institut de Ciència dels Materials (ICMUV), Universidad de Valencia P.O. Box 2085, 46071 Valencia (Spain)
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257
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Agostini A, Mondragón L, Pascual L, Aznar E, Coll C, Martínez-Máñez R, Sancenón F, Soto J, Marcos MD, Amorós P, Costero AM, Parra M, Gil S. Design of enzyme-mediated controlled release systems based on silica mesoporous supports capped with ester-glycol groups. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:14766-14776. [PMID: 22998170 DOI: 10.1021/la303161e] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
An ethylene glycol-capped hybrid material for the controlled release of molecules in the presence of esterase enzyme has been prepared. The final organic-inorganic hybrid solid S1 was synthesized by a two-step procedure. In the first step, the pores of an inorganic MCM-41 support (in the form of nanoparticles) were loaded with [Ru(bipy)(3)]Cl(2) complex, and then, in the second step, the pore outlets were functionalized with ester glycol moieties that acted as molecular caps. In the absence of an enzyme, release of the complex from aqueous suspensions of S1 at pH 8.0 is inhibited due to the steric hindrance imposed by the bulky ester glycol moieties. Upon addition of esterase enzyme, delivery of the ruthenium complex was observed due to enzymatic hydrolysis of the ester bond in the anchored ester glycol derivative, inducing the release of oligo(ethylene glycol) fragments. Hydrolysis of the ester bond results in size reduction of the appended group, therefore allowing delivery of the entrapped cargo. The S1 nanoparticles were not toxic for cells, as demonstrated by cell viability assays with HeLa and MCF-7 cell lines, and were found to be associated with lysosomes, as shown by confocal microscopy. However, when S1 nanoparticles were filled with the cytotoxic drug camptothecin (S1-CPT), S1-CPT-treated cells undergo cell death as a result of S1-CPT cell internalization and subsequent cellular enzyme-mediated hydrolysis and aperture of the molecular gate that induced the release of the camptothecin cargo. These findings point to a possible therapeutic application of these nanoparticles.
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Affiliation(s)
- Alessandro Agostini
- Centro de Reconocimiento Molecular y Desarrollo Tecnológico, Unidad Mixta Universidad Politécnica de Valencia-Universidad de Valencia, Valencia, Spain
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258
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Barin G, Forgan RS, Stoddart JF. Mechanostereochemistry and the mechanical bond. Proc Math Phys Eng Sci 2012; 468:2849-2880. [PMID: 22977353 PMCID: PMC3438546 DOI: 10.1098/rspa.2012.0117] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Accepted: 04/12/2012] [Indexed: 11/12/2022] Open
Abstract
The chemistry of mechanically interlocked molecules (MIMs), in which two or more covalently linked components are held together by mechanical bonds, has led to the coining of the term mechanostereochemistry to describe a new field of chemistry that embraces many aspects of MIMs, including their syntheses, properties, topologies where relevant and functions where operative. During the rapid development and emergence of the field, the synthesis of MIMs has witnessed the forsaking of the early and grossly inefficient statistical approaches for template-directed protocols, aided and abetted by molecular recognition processes and the tenets of self-assembly. The resounding success of these synthetic protocols, based on templation, has facilitated the design and construction of artificial molecular switches and machines, resulting more and more in the creation of integrated functional systems. This review highlights (i) the range of template-directed synthetic methods being used currently in the preparation of MIMs; (ii) the syntheses of topologically complex knots and links in the form of stable molecular compounds; and (iii) the incorporation of bistable MIMs into many different device settings associated with surfaces, nanoparticles and solid-state materials in response to the needs of particular applications that are perceived to be fair game for mechanostereochemistry.
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Affiliation(s)
- Gokhan Barin
- Department of Chemistry, Center for the Chemistry of Integrated Systems, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3133, USA
- NanoCentury KAIST Institute and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1, Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Ross S. Forgan
- Department of Chemistry, Center for the Chemistry of Integrated Systems, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3133, USA
- School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - J. Fraser Stoddart
- Department of Chemistry, Center for the Chemistry of Integrated Systems, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3133, USA
- NanoCentury KAIST Institute and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1, Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
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259
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Colilla M, González B, Vallet-Regí M. Mesoporous silica nanoparticles for the design of smart delivery nanodevices. Biomater Sci 2012; 1:114-134. [PMID: 32481793 DOI: 10.1039/c2bm00085g] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mesoporous silica nanoparticles (MSNPs) are receiving growing attention by the scientific community for their groundbreaking potential in nanomedicine. It is possible to load huge amounts of cargo into the mesopore voids and capping the pore entrances with different nanogates. Different internal or external stimuli can provoke the nanocap removal and trigger the departure of the cargo, which permits the design of stimuli-responsive drug delivery nanodevices. It is also feasible to combine the multifunctionality of MSNPs with the wide range of applications of magnetic nanoparticles (mNPs), giving rise to advanced smart nanosystems whose features and functionality can be tailored attending to specific clinical needs. This review describes the possible combinations of MSNPs, stimuli-responsive nanocaps and mNPs and the current scientific challenges aimed at accelerating the progression from bench to bedside.
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Affiliation(s)
- Montserrat Colilla
- Departamento de Química Inorgánica y Bioinorgánica, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza Ramón y Cajal s/n, 28040 Madrid, Spain.
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260
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Fahrenbach AC, Bruns CJ, Cao D, Stoddart JF. Ground-state thermodynamics of bistable redox-active donor-acceptor mechanically interlocked molecules. Acc Chem Res 2012; 45:1581-92. [PMID: 22741809 DOI: 10.1021/ar3000629] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Fashioned through billions of years of evolution, biological molecular machines, such as ATP synthase, myosin, and kinesin, use the intricate relative motions of their components to drive some of life's most essential processes. Having control over the motions in molecules is imperative for life to function, and many chemists have designed, synthesized, and investigated artificial molecular systems that also express controllable motions within molecules. Using bistable mechanically interlocked molecules (MIMs), based on donor-acceptor recognition motifs, we have sought to imitate the sophisticated nanoscale machines present in living systems. In this Account, we analyze the thermodynamic characteristics of a series of redox-switchable [2]rotaxanes and [2]catenanes. Control and understanding of the relative intramolecular movements of components in MIMs have been vital in the development of a variety of applications of these compounds ranging from molecular electronic devices to drug delivery systems. These bistable donor-acceptor MIMs undergo redox-activated switching between two isomeric states. Under ambient conditions, the dominant translational isomer, the ground-state coconformation (GSCC), is in equilibrium with the less favored translational isomer, the metastable-state coconformation (MSCC). By manipulating the redox state of the recognition site associated with the GSCC, we can stimulate the relative movements of the components in these bistable MIMs. The thermodynamic parameters of model host-guest complexes provide a good starting point to rationalize the ratio of GSCC to MSCC at equilibrium. The bistable [2]rotaxanes show a strong correlation between the relative free energies of model complexes and the ground-state distribution constants (K(GS)). This relationship does not always hold for bistable [2]catenanes, most likely because of the additional steric and electronic constraints present when the two rings are mechanically interlocked with each other. Measuring the ground-state distribution constants of bistable MIMs presents its own set of challenges. While it is possible, in principle, to determine these constants using NMR and UV-vis spectroscopies, these methods lack the sensitivity to permit the determination of ratios of translational isomers greater than 10:1 with sufficient accuracy and precision. A simple application of the Nernst equation, in combination with variable scan-rate cyclic voltammetry, however, allows the direct measurement of ground-state distribution constants across a wide range (K(GS) = 10-10(4)) of values.
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Affiliation(s)
- Albert C. Fahrenbach
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States, and NanoCentury KAIST Institute, Graduate School of Energy, Environment, Water, and Sustainability (World Class University), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Carson J. Bruns
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States, and NanoCentury KAIST Institute, Graduate School of Energy, Environment, Water, and Sustainability (World Class University), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Dennis Cao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States, and NanoCentury KAIST Institute, Graduate School of Energy, Environment, Water, and Sustainability (World Class University), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - J. Fraser Stoddart
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States, and NanoCentury KAIST Institute, Graduate School of Energy, Environment, Water, and Sustainability (World Class University), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
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261
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Stoica G, Castelló Serrano I, Figuerola A, Ugarte I, Pacios R, Palomares E. Layered double hydroxides as carriers for quantum dots@silica nanospheres. NANOSCALE 2012; 4:5409-5419. [PMID: 22825338 DOI: 10.1039/c2nr31550e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Quantum dot-hydrotalcite layered nanoplatforms were successfully prepared following a one-pot synthesis. The process is very fast and a priori delamination of hydrotalcite is not a prerequisite for the intercalation of quantum dots. The novel materials were extensively characterized by X-ray diffraction, thermogravimetry, infrared spectroscopy, transmission electron microscopy, true color fluorescence microscopy, photoluminescence, and nitrogen adsorption. The quantum dot-hydrotalcite nanomaterials display extremely high stability in mimicking physiological media such as saline serum (pH 5.5) and PBS (pH 7.2). Yet, quantum dot release from the solid structure is noted. In order to prevent the leaking of quantum dots we have developed a novel strategy which consists of using tailor made double layered hydrotalcites as protecting shells for quantum dots embedded into silica nanospheres without changing either the materials or the optical properties.
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Affiliation(s)
- Georgiana Stoica
- Institute of Chemical Research of Catalonia-ICIQ, Avinguda del Paisos Catalans 16, 43007 Tarragona, Spain
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262
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Wan MM, Yang JY, Qiu Y, Zhou Y, Guan CX, Hou Q, Lin WG, Zhu JH. Sustained release of heparin on enlarged-pore and functionalized MCM-41. ACS APPLIED MATERIALS & INTERFACES 2012; 4:4113-22. [PMID: 22850329 DOI: 10.1021/am300878z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Mesoporous silica MCM-41 and SBA-15 were chosen to study the adsorption and release of bulky biomolecule heparin, in order to develop new heparin controlled delivery system and expand the application of mesoporous materials in life science. To explore how the structure of support such as pore size and surface state affects the accommodation and release of heparin, we used decane as swelling agent to enlarge pores of MCM-41, introduced amino groups for improving the biocompatibility of support, and controllably retained templates in the as-synthesized sample. The influence of modification on the structure of samples was investigated by XRD and N(2) adsorption-desorption, whereas their performance of adsorbing and releasing heparin was assessed with that of toluidine blue method. Both enlarged pore and organic modification significantly promoted the adsorption and prolonged the release of heparin in MCM-41, and the release was characterized with a three-stage release model. The mechanism of heparin release from mesoporous material was studied by fitting the release profiles to the theoretical equation. As expected, some mesoporous composites could release heparin in the long term with tuned dosage.
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Affiliation(s)
- Mi Mi Wan
- Key Laboratory of Mesoscopic Chemistry of MOE, College of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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263
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Lohmann F, Ackermann D, Famulok M. Reversible light switch for macrocycle mobility in a DNA rotaxane. J Am Chem Soc 2012; 134:11884-7. [PMID: 22780815 PMCID: PMC3404550 DOI: 10.1021/ja3042096] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Indexed: 01/21/2023]
Abstract
A recent trend in DNA nanotechnology consists of the assembly of architectures with dynamic properties that can be regulated by employing external stimuli. Reversible processes are important for implementing molecular motion into DNA architectures as they allow for the regeneration of the original state. Here we describe two different approaches for the reversible switching of a double-stranded DNA rotaxane architecture from a stationary pseudorotaxane mode into a state with movable components. Both states only marginally differ in their respective topologies but their mechanical properties are fundamentally different. In the two approaches, the switching operation is based on strand-displacement reactions. One of them employs toehold-extended oligodeoxynucleotides whereas in the other one the switching is achieved by light-irradiation. In both cases, multiple back and forth switching between the stationary and the mobile states was achieved in nearly quantitative fashion. The ability to reversibly operate mechanical motion in an interlocked DNA nanostructure opens exciting new avenues in DNA nanotechnology.
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Affiliation(s)
| | | | - Michael Famulok
- LIMES Institute,
Chemical Biology & Medicinal Chemistry
Unit, c/o Kekulé Institute of Organic Chemistry
and Biochemistry, Gerhard-Domagk-Strasse 1, 53121 Bonn,
Germany
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264
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Mu Q, Hondow NS, Krzemiński L, Brown AP, Jeuken LJC, Routledge MN. Mechanism of cellular uptake of genotoxic silica nanoparticles. Part Fibre Toxicol 2012; 9:29. [PMID: 22823932 PMCID: PMC3479067 DOI: 10.1186/1743-8977-9-29] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 07/12/2012] [Indexed: 12/30/2022] Open
Abstract
Mechanisms for cellular uptake of nanoparticles have important implications for nanoparticulate drug delivery and toxicity. We have explored the mechanism of uptake of amorphous silica nanoparticles of 14 nm diameter, which agglomerate in culture medium to hydrodynamic diameters around 500 nm. In HT29, HaCat and A549 cells, cytotoxicity was observed at nanoparticle concentrations ≥ 1 μg/ml, but DNA damage was evident at 0.1 μg/ml and above. Transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy confirmed entry of the silica particles into A549 cells exposed to 10 μg/ml of nanoparticles. The particles were observed in the cytoplasm but not within membrane bound vesicles or in the nucleus. TEM of cells exposed to nanoparticles at 4°C for 30 minutes showed particles enter cells when activity is low, suggesting a passive mode of entry. Plasma lipid membrane models identified physical interactions between the membrane and the silica NPs. Quartz crystal microbalance experiments on tethered bilayer lipid membrane systems show that the nanoparticles strongly bind to lipid membranes, forming an adherent monolayer on the membrane. Leakage assays on large unilamellar vesicles (400 nm diameter) indicate that binding of the silica NPs transiently disrupts the vesicles which rapidly self-seal. We suggest that an adhesive interaction between silica nanoparticles and lipid membranes could cause passive cellular uptake of the particles.
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Affiliation(s)
- Qingshan Mu
- Centre for Molecular NanoScience (CMNS), University of Leeds, Leeds LS2 9JT, UK
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265
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Sreejith S, Ma X, Zhao Y. Graphene Oxide Wrapping on Squaraine-Loaded Mesoporous Silica Nanoparticles for Bioimaging. J Am Chem Soc 2012; 134:17346-9. [DOI: 10.1021/ja305352d] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Sivaramapanicker Sreejith
- Division of Chemistry and Biological
Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link,
637371 Singapore
| | - Xing Ma
- School
of Materials Science
and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Yanli Zhao
- Division of Chemistry and Biological
Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link,
637371 Singapore
- School
of Materials Science
and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
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266
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Megiatto JD, Schuster DI, de Miguel G, Wolfrum S, Guldi DM. Topological and Conformational Effects on Electron Transfer Dynamics in Porphyrin-[60]Fullerene Interlocked Systems. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2012; 24:2472-2485. [PMID: 22984324 PMCID: PMC3439220 DOI: 10.1021/cm3004408] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The effect of molecular topology, and conformation on the dynamics of photoinduced electron transfer (ET) processes has been studied in interlocked electron donor-acceptor systems, specifically rotaxanes with zinc(II)-tetraphenylporphyrin (ZnP) electron donor and [60]fullerene (C(60)) as the electron acceptor. Formation or cleavage of coordinative bonds was used to induce major topological and conformational changes in the interlocked architecture. In the first approach, the tweezers-like structure created by the two ZnP stopper groups on the thread was used as a recognition site for complexation of 1,4-diazabicyclo[2.2.2]octane (DABCO), which creates a bridge between the two ZnP moieties on the rotaxane, generating a catenane structure. The photoinduced processes in the DABCO-complexed (ZnP)(2)-[2]catenate-C(60) system were compared with those of the (ZnP)(2)-rotaxane-C(60) precursor and the previously reported ZnP-[2]catenate-C(60). Steady-state emission and transient absorption studies showed that a similar multistep ET pathway emerged for rotaxanes and catenanes upon photoexcitation at various wavelengths, ultimately resulting in a long-lived ZnP(•+)/C(60) (•-) charge separated radical pair state. However, the decay kinetics of the latter states clearly reflect the topological differences between the rotaxane, the catenate, and DABCO-complexed-catenate architectures. The lifetime of the long-distance ZnP(•+)-[Cu(I)phen(2)](+)-C(60) (•-) charge separated state is more than four times longer in 3 (1.03 µs) than in 1 (0.24 µs) and approaches that in catenate 2 (1.1 µs). The results clearly showed that adoption of a catenane from a rotaxane topology inhibits the charge recombination process. In a second approach, the Cu(I) ion used as template to assemble the (ZnP)(2)-[Cu(I)phen(2)](+)-C(60) rotaxane was removed, and structural analysis suggested a major topographical change occurred, such that charge separation between the chromophores was no longer observed upon photoexcitation in nonpolar as well as polar solvents. Only ZnP and C(60) triplet excited states were observed upon laser excitation. These results highlighted the critical importance of the central Cu(I) ion for long range ET processes in these large interlocked electron donor-acceptor systems.
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Affiliation(s)
| | - David I. Schuster
- Department of Chemistry, New York University, New York, NY 10003, USA
| | - Gustavo de Miguel
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Silke Wolfrum
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Dirk M. Guldi
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
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267
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Sun YL, Yang BJ, Zhang SXA, Yang YW. Cucurbit[7]uril Pseudorotaxane-Based Photoresponsive Supramolecular Nanovalve. Chemistry 2012; 18:9212-6. [DOI: 10.1002/chem.201201083] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Indexed: 11/11/2022]
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268
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Lau YA, Henderson BL, Lu J, Ferris DP, Tamanoi F, Zink JI. Continuous spectroscopic measurements of photo-stimulated release of molecules by nanomachines in a single living cell. NANOSCALE 2012; 4:3482-3489. [PMID: 22552632 PMCID: PMC3388114 DOI: 10.1039/c2nr30524k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The first continuous, real-time spectroscopic monitoring of a photo-driven cargo delivery event from a mesoporous silica-based nanocarrier inside a single living cell is reported. By chemically attaching azobenzene molecules inside the 3 nm pore channels of mesoporous silica nanoparticles (∼70 nm diameter), the escape of the cargo molecule [propidium iodide (PI)] from the pore is prevented in the dark but is facilitated by the light-driven isomerization motion. Real-time spectroscopic measurements of a single cell uncover intermediate processes that occur during this intracellular delivery event, from nanomachine activation to the release of PI into the cytosol and to PI's eventual intercalation with nuclear DNA. Changes in PI's fluorescence intensity and the hypsochromic shift of the band maxima are used to identify the local environment of the fluorophore that is being observed in the cell. The ability to precisely initiate a chemical event inside an individual cell and continuously monitor the subsequent biological responses will enhance our understanding of intracellular process upon drug, protein and nucleic acid delivery.
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Affiliation(s)
- Yuen A Lau
- Department of Chemistry & Biochemistry, University of California Los Angeles, Los Angeles, CA 90095-1569, USA
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269
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Fang IJ, Slowing II, Wu KCW, Lin VSY, Trewyn BG. Ligand Conformation Dictates Membrane and Endosomal Trafficking of Arginine-Glycine-Aspartate (RGD)-Functionalized Mesoporous Silica Nanoparticles. Chemistry 2012; 18:7787-92. [DOI: 10.1002/chem.201200023] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Indexed: 01/07/2023]
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270
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Zhou Y, Li K, Yang JY, Guan CX, Wang Y, Liu CJ, Zhu JH. Small-caliber vascular prosthesis prototype based on controlled release of heparin from mesochannels and its enhanced biocompatibility. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:1373-1383. [PMID: 22378541 DOI: 10.1002/smll.201101270] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Revised: 08/21/2011] [Indexed: 05/31/2023]
Abstract
A novel small-caliber vascular prosthesis prototype is proposed on the basis of a new heparin release system, that is, the controlled delivery of heparin from mesochannels. Fabrication of mesochannels on artificial biomaterials is successfully achieved through epitaxial growth of mesoporous silica nanoparticles on expanded polytetrafluoroethylene grafts, and thus heparin can be immobilized through a space limitation effect, thereby avoiding the loss of bioactivity and enabling long-lasting release. The adsorption and release of heparin are controlled by adjusting the adsorbate-adsorbent interaction through tailoring the mesostructure. Owing to the continuous and sustained release of heparin, the performances of artificial vessels are greatly improved, thus paving a new way to prepare functional blood-contacting biomaterials with high biocompatibility.
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Affiliation(s)
- Yu Zhou
- Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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271
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Zhang D, Tong A, Zhou L, Fang F, Guo G. Osteogenic differentiation of human placenta-derived mesenchymal stem cells (PMSCs) on electrospun nanofiber meshes. Cytotechnology 2012; 64:701-10. [PMID: 22526490 DOI: 10.1007/s10616-012-9450-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 03/19/2012] [Indexed: 02/05/2023] Open
Abstract
Numerous challenges remain in the successful clinical translation of cell-based therapeutic studies for skeletal tissue repair, including appropriate cell sources and viable cell delivery systems. Poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) amphiphilic block copolymers have been extensively explored in microspheres preparation. Due to the introduction of hydrophilic PEG segments into PCL backbones, these copolymers have shown much more potentials in carrying protein, lipophilic drugs or genes than commonly used poly (ε-caprolactone) (PCL) and poly (lactic acid). The aim of this study is to investigate the attachment and osteogenic differentiation of human placenta derived mesenchymal stem cells (PMSCs) on PEG-PCL triblock copolymers nanofiber scaffolds. Here we demonstrated that PMSCs proliferate robustly and can be effectively differentiated into osteogenic-like cells on nanofiber scaffolds. This study provides evidence for the use of nanofiber scaffolds as an ideal supporting material for in vitro PMSCs culture and an in vivo cell delivery vehicle for bone repair.
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Affiliation(s)
- Dongmei Zhang
- State Key Laboratory of Biotherapy and Cancer Center West China Hospital, West China Medical School, Sichuan University, Chengdu, 610041, People's Republic of China
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272
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Wang C, Li Z, Cao D, Zhao YL, Gaines JW, Bozdemir OA, Ambrogio MW, Frasconi M, Botros YY, Zink JI, Stoddart JF. Stimulated Release of Size-Selected Cargos in Succession from Mesoporous Silica Nanoparticles. Angew Chem Int Ed Engl 2012; 51:5460-5. [DOI: 10.1002/anie.201107960] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 03/07/2012] [Indexed: 11/08/2022]
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273
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Wang C, Li Z, Cao D, Zhao YL, Gaines JW, Bozdemir OA, Ambrogio MW, Frasconi M, Botros YY, Zink JI, Stoddart JF. Stimulated Release of Size-Selected Cargos in Succession from Mesoporous Silica Nanoparticles. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201107960] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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274
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Figueira F, Cavaleiro JA, Tomé JP. Silica nanoparticles functionalized with porphyrins and analogs for biomedical studies. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424611003653] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This review focus on the preparation of silica nanoparticles functionalized with porphyrins and related compounds. It is aimed to highlight their features as photosensitizers in the area of photodynamic therapy. In this field, photosensitizers have been covalently and non-covalently linked to silica nanoparticles, in order to study their photophysical and biological properties. Another fascinating scenario for photosensitizer-silica nanoparticles hybrids involves the possibility of including metal cores for conditioning the uptake in the target cells, allowing most of the times the combination of therapies and in certain conditions to facilitate the removal and reutilization of the photosensitizer in environmental applications.
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Affiliation(s)
- Flávio Figueira
- Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | | | - João P.C. Tomé
- Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
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275
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Sinha MK, Reany O, Yefet M, Botoshansky M, Keinan E. Bistable Cucurbituril Rotaxanes Without Stoppers. Chemistry 2012; 18:5589-605. [DOI: 10.1002/chem.201103434] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Indexed: 11/06/2022]
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276
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Biyikal M, Hecht M, Martínez-Máñez R, Rurack K, Sancenón F. Supramolecular Hybrid Nanomaterials As Prospective Sensing Platforms. Supramol Chem 2012. [DOI: 10.1002/9780470661345.smc199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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277
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Barin G, Coskun A, Fouda MMG, Stoddart JF. Mechanically Interlocked Molecules Assembled by π-π Recognition. Chempluschem 2012. [DOI: 10.1002/cplu.201100075] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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278
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Cheang TY, Tang B, Xu AW, Chang GQ, Hu ZJ, He WL, Xing ZH, Xu JB, Wang M, Wang SM. Promising plasmid DNA vector based on APTES-modified silica nanoparticles. Int J Nanomedicine 2012; 7:1061-7. [PMID: 22403488 PMCID: PMC3292418 DOI: 10.2147/ijn.s28267] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Nanoparticles have an enormous potential for development in biomedical applications, such as gene or drug delivery. We developed and characterized aminopropyltriethoxysilane-functionalized silicon dioxide nanoparticles (APTES-SiNPs) for gene therapy. Lipofectamine® 2000, a commonly used agent, served as a contrast. We showed that APTES-SiNPs had a gene transfection efficiency almost equal to that of Lipofectamine 2000, but with lower cytotoxicity. Thus, these novel APTES-SiNPs can achieve highly efficient transfection of plasmid DNA, and to some extent reduce cytotoxicity, which might overcome the critical drawbacks in vivo of conventional carriers, such as viral vectors, organic polymers, and liposomes, and seem to be a promising nonviral gene therapy vector.
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Affiliation(s)
- Tuck-yun Cheang
- Department of Vascular Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
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279
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Targeted intracellular delivery of antituberculosis drugs to Mycobacterium tuberculosis-infected macrophages via functionalized mesoporous silica nanoparticles. Antimicrob Agents Chemother 2012; 56:2535-45. [PMID: 22354311 DOI: 10.1128/aac.06049-11] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Delivery of antituberculosis drugs by nanoparticles offers potential advantages over free drug, including the potential to target specifically the tissues and cells that are infected by Mycobacterium tuberculosis, thereby simultaneously increasing therapeutic efficacy and decreasing systemic toxicity, and the capacity for prolonged release of drug, thereby allowing less-frequent dosing. We have employed mesoporous silica nanoparticle (MSNP) drug delivery systems either equipped with a polyethyleneimine (PEI) coating to release rifampin or equipped with cyclodextrin-based pH-operated valves that open only at acidic pH to release isoniazid (INH) into M. tuberculosis-infected macrophages. The MSNP are internalized efficiently by human macrophages, traffic to acidified endosomes, and release high concentrations of antituberculosis drugs intracellularly. PEI-coated MSNP show much greater loading of rifampin than uncoated MSNP and much greater efficacy against M. tuberculosis-infected macrophages. MSNP were devoid of cytotoxicity at the particle doses employed for drug delivery. Similarly, we have demonstrated that the isoniazid delivered by MSNP equipped with pH-operated nanovalves kill M. tuberculosis within macrophages significantly more effectively than an equivalent amount of free drug. These data demonstrate that MSNP provide a versatile platform that can be functionalized to optimize the loading and intracellular release of specific drugs for the treatment of tuberculosis.
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280
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Aznar E, Sancenón F, Marcos MD, Martínez-Máñez R, Stroeve P, Cano J, Amorós P. Delivery modulation in silica mesoporous supports via alkyl chain pore outlet decoration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:2986-2996. [PMID: 22181346 DOI: 10.1021/la204438j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This article focuses on the study of the release rate in a family of modified silica mesoporous supports. A collection of solids containing ethyl, butyl, hexyl, octyl, decyl, octadecyl, docosyl, and triacontyl groups anchored on the pore outlets of mesoporous MCM-41 has been prepared and characterized. Controlled release from pore voids has been studied through the delivery of the dye complex tris(2,2'-bipyridyl)ruthenium(II). Delivery rates were found to be dependent on the alkyl chain length anchored on the pore outlets of the mesoporous scaffolding. Moreover, release rates follow a Higuchi diffusion model, and Higuchi constants for the different hybrid solids have been calculated. A decrease of the Higuchi constants was observed as the alkyl chain used to tune the release profile is longer, confirming the effect that the different alkyl chains anchored into the pore mouths exerted on the delivery of the cargo. Furthermore, to better understand the relation between pore outlets decoration and release rate, studies using molecular dynamics simulations employing force-field methods have been carried out. A good agreement between the calculations and the experimental observations was observed.
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Affiliation(s)
- Elena Aznar
- Centro de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Unidad Mixta Universitat Politècnica de València-Universitat de València, Spain
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281
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Lee H, Kim S, Choi BH, Park MT, Lee J, Jeong SY, Choi EK, Lim BU, Kim C, Park HJ. Hyperthermia improves therapeutic efficacy of doxorubicin carried by mesoporous silica nanocontainers in human lung cancer cells. Int J Hyperthermia 2012; 27:698-707. [PMID: 21992562 DOI: 10.3109/02656736.2011.608217] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
PURPOSE We investigated the use of hyperthermia to improve the anti-cancer efficacy of doxorubicin (DOX)-loaded mesoporous silica nanocontainer Si-SS-CD-PEG. The hypothesis was that heat stimulates glutathione-mediated degradation of cyclodextrin gatekeeper, thereby causing the release of DOX from the carrier and DOX-induced cell death. MATERIALS AND METHODS The release of DOX from DOX-loaded Si-SS-CD-PEG suspended in PBS containing glutathione (GSH) was studied by assessing the changes in DOX fluorescence intensity. The effect of heating at 42°C on the release of DOX from the intracellular carriers was determined with confocal microscopy. The extents of clonogenic and apoptotic cell death caused by DOX-loaded Si-SS-CD-PEG were determined. RESULTS The release of DOX from DOX-loaded Si-SS-CD-PEG in PBS occurred only when GSH presented in the suspension, and heating at 42°C slightly increased the release of DOX from the carriers. Heating significantly elevated the GSH content in A549 cells and increased the release of DOX from the internalised carriers. Heating the cancer cells treated with the carriers at 42°C markedly increased the clonogenic death and apoptosis. The GSH content in A549 cells was greater than that in L-132 cells, and A549 cells were far more sensitive than L-132 cells to DOX-loaded Si-SS-CD-PEG at both 37°C and 42°C. CONCLUSIONS Hyperthermia increased the GSH-mediated release of DOX from DOX-loaded Si-SS-CD-PEG. Furthermore, hyperthermia markedly elevated the GSH content in cancer cells, thereby increasing the release of DOX from the internalised carriers and potentiating the DOX-induced clonogenic and apoptotic cell death.
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Affiliation(s)
- Hyemi Lee
- Department of Microbiology, Center for Advanced Medical Education by BK21 Project, College of Medicine, Inha University, Incheon, Korea
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282
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Gary-Bobo M, Hocine O, Brevet D, Maynadier M, Raehm L, Richeter S, Charasson V, Loock B, Morère A, Maillard P, Garcia M, Durand JO. Cancer therapy improvement with mesoporous silica nanoparticles combining targeting, drug delivery and PDT. Int J Pharm 2012; 423:509-15. [DOI: 10.1016/j.ijpharm.2011.11.045] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 11/28/2011] [Accepted: 11/29/2011] [Indexed: 01/19/2023]
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283
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Fahrenbach AC, Barnes JC, Lanfranchi DA, Li H, Coskun A, Gassensmith JJ, Liu Z, Benítez D, Trabolsi A, Goddard WA, Elhabiri M, Stoddart JF. Solution-Phase Mechanistic Study and Solid-State Structure of a Tris(bipyridinium radical cation) Inclusion Complex. J Am Chem Soc 2012; 134:3061-72. [PMID: 22148229 DOI: 10.1021/ja2089603] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Albert C. Fahrenbach
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- NanoCentury KAIST
Institute
and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong,
Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Jonathan C. Barnes
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- NanoCentury KAIST
Institute
and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong,
Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Don Antoine Lanfranchi
- Laboratoire de Chimie Bioorganique
et Médicinale, UMR 7509 CNRS-UdS, ECPM, Université de Strasbourg, 25 rue Becquerel, 67200 Strasbourg, France
| | - Hao Li
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
| | - Ali Coskun
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- NanoCentury KAIST
Institute
and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong,
Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Jeremiah J. Gassensmith
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
| | - Zhichang Liu
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
| | - Diego Benítez
- Materials and Process Simulation
Center, California Institute of Technology, Pasadena, California 91125, United States
| | - Ali Trabolsi
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- Center for Science and Engineering, New York University Abu Dhabi, Abu Dhabi, United Arab
Emirates
| | - William A. Goddard
- Materials and Process Simulation
Center, California Institute of Technology, Pasadena, California 91125, United States
- NanoCentury KAIST
Institute
and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong,
Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - Mourad Elhabiri
- Laboratoire de Chimie Bioorganique
et Médicinale, UMR 7509 CNRS-UdS, ECPM, Université de Strasbourg, 25 rue Becquerel, 67200 Strasbourg, France
| | - J. Fraser Stoddart
- Department
of Chemistry, Northwestern University,
2145 Sheridan Road, Evanston,
Illinois 60208, United States
- NanoCentury KAIST
Institute
and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong,
Yuseong Gu, Daejeon 305-701, Republic of Korea
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284
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Hyaluronic acid-functionalized mesoporous silica nanoparticles for efficient photodynamic therapy of cancer cells. Photodiagnosis Photodyn Ther 2012; 9:256-60. [PMID: 22959805 DOI: 10.1016/j.pdpdt.2011.12.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 12/13/2011] [Accepted: 12/27/2011] [Indexed: 01/25/2023]
Abstract
Mesoporous silica nanoparticles (MSN) for photodynamic therapy (PDT) were coated with poly-(L-lysine) and hyaluronic acid (HA) by using the layer-by-layer method. HA is able to target cancer cells over-expressing the corresponding CD44 receptor. MSN functionalized with HA (MSN-HA) were more efficient than MSN without the targeting moiety when PDT was performed at low fluence (14 Jcm(-2)) and low dosage of MSN (20 μgmL(-1)) on HCT 116 colorectal cancer cells, known to over-express the CD44 receptor. Incubation of HCT-116 cancer cells with an excess of HA impaired the PDT effect with MSN-HA thus demonstrating that an active endocytosis mechanism was involved in the uptake of MSN-HA by these cells.
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285
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Sánchez-Muñoz S, Gómez-Ruiz S, Pérez-Quintanilla D, Morante-Zarcero S, Sierra I, Prashar S, Paschke R, Kaluđerović GN. Preliminary study of the anticancer applications of mesoporous materials functionalized with the natural product betulinic acid. ChemMedChem 2012; 7:670-9. [PMID: 22278996 DOI: 10.1002/cmdc.201100588] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Indexed: 12/30/2022]
Abstract
Dehydrated MCM-41 (S1) was functionalized under nitrogen with 3-chloropropyltriethoxysilane (CPTS) and 3-aminopropyltriethoxysilane (APTS) by grafting in toluene at 80 °C over 48 h to give the corresponding materials S2 and S3, respectively. Subsequently, S2 and S3 were suspended in methanol and reacted in a nitrogen atmosphere with betulinic acid (BA) for 48 h at 65 °C (in the presence of the triethylamine of S2) to give the BA-functionalized materials S4 and S5. All materials studied were characterized by powder X-ray diffraction, X-ray fluorescence, nitrogen gas sorption, multinuclear MAS NMR spectroscopy, thermogravimetry, UV spectroscopy, IR, SEM, and TEM. To study the release of BA, S4 and S5 were suspended in solutions simulating various body pH conditions (pH 7.4, 5.5, and 3.0). Results of the quantification of BA release by HPLC for S4 show a pH-dependent and very slow BA release following a logarithmic tendency, while S5 behaves differently, also pH-dependent but, in this case, fast release of BA which requires only days for total release of the therapeutic compound. In addition, the cytotoxic activity of all synthesized materials against various cancer cell lines was studied. The results show the absence of an antiproliferative effect on the surfaces without BA S1-S3, while an antiproliferative effect was observed with S4 and S5 and was attributed to the release of BA in the medium.
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Affiliation(s)
- Sergio Sánchez-Muñoz
- Departamento de Química Inorgánica y Analítica, E.S.C.E.T. Universidad Rey Juan Carlos, 28933 Móstoles, Madrid, Spain
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286
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Wang C, Cao D, Fahrenbach AC, Fang L, Olson MA, Friedman DC, Basu S, Dey SK, Botros YY, Stoddart JF. Solvent-dependent ground-state distributions in a donor-acceptor redox-active bistable [2]catenane. J PHYS ORG CHEM 2012. [DOI: 10.1002/poc.1960] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Cheng Wang
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Dennis Cao
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
- NanoCentury KAIST Institute and Graduate School of EEWS (WCU); Korea Advanced Institute of Science and Technology (KAIST)373-1; Guseong Dong Yuseong Gu Daejeon 305-701 Korea
| | - Albert C. Fahrenbach
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
- NanoCentury KAIST Institute and Graduate School of EEWS (WCU); Korea Advanced Institute of Science and Technology (KAIST)373-1; Guseong Dong Yuseong Gu Daejeon 305-701 Korea
| | - Lei Fang
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Mark A. Olson
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Douglas C. Friedman
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Subhadeep Basu
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Sanjeev K. Dey
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
| | - Youssry Y. Botros
- Department of Materials Science and Engineering; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
- Intel Labs; Building RNB-6-61, 2200 Mission College Blvd. Santa Clara CA 95054 USA
- National Center for Nano Technology Research; King Abdulaziz City for Science and Technology (KACST); Riyadh 11442 Saudi Arabia
| | - J. Fraser Stoddart
- Department of Chemistry; Northwestern University; 2145 Sheridan Road Evanston IL 60208 USA
- NanoCentury KAIST Institute and Graduate School of EEWS (WCU); Korea Advanced Institute of Science and Technology (KAIST)373-1; Guseong Dong Yuseong Gu Daejeon 305-701 Korea
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287
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Li Z, Barnes JC, Bosoy A, Stoddart JF, Zink JI. Mesoporous silica nanoparticles in biomedical applications. Chem Soc Rev 2012; 41:2590-605. [PMID: 22216418 DOI: 10.1039/c1cs15246g] [Citation(s) in RCA: 1225] [Impact Index Per Article: 102.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This tutorial review provides an outlook on nanomaterials that are currently being used for theranostic purposes, with a special focus on mesoporous silica nanoparticle (MSNP) based materials. MSNPs with large surface area and pore volume can serve as efficient carriers for various therapeutic agents. The functionalization of MSNPs with molecular, supramolecular or polymer moieties, provides the material with great versatility while performing drug delivery tasks, which makes the delivery process highly controllable. This emerging area at the interface of chemistry and the life sciences offers a broad palette of opportunities for researchers with interests ranging from sol-gel science, the fabrication of nanomaterials, supramolecular chemistry, controllable drug delivery and targeted theranostics in biology and medicine.
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Affiliation(s)
- Zongxi Li
- California NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, 607 Charles E. Young Drive East, Los Angeles, California 90095, USA
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288
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Avellini T, Li H, Coskun A, Barin G, Trabolsi A, Basuray AN, Dey SK, Credi A, Silvi S, Stoddart JF, Venturi M. Photoinduced Memory Effect in a Redox Controllable Bistable Mechanical Molecular Switch. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201107618] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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289
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Avellini T, Li H, Coskun A, Barin G, Trabolsi A, Basuray AN, Dey SK, Credi A, Silvi S, Stoddart JF, Venturi M. Photoinduced Memory Effect in a Redox Controllable Bistable Mechanical Molecular Switch. Angew Chem Int Ed Engl 2012; 51:1611-5. [PMID: 22213358 DOI: 10.1002/anie.201107618] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Indexed: 11/09/2022]
Affiliation(s)
- Tommaso Avellini
- Dipartimento di Chimica G. Ciamician, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
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290
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Pramanik M, Nandi M, Uyama H, Bhaumik A. Organic–inorganic hybrid tinphosphonate material with mesoscopic void spaces: an excellent catalyst for the radical polymerization of styrene. Catal Sci Technol 2012. [DOI: 10.1039/c2cy00352j] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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291
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Lewis JEM, Gavey EL, Cameron SA, Crowley JD. Stimuli-responsive Pd2L4metallosupramolecular cages: towards targeted cisplatin drug delivery. Chem Sci 2012. [DOI: 10.1039/c2sc00899h] [Citation(s) in RCA: 323] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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292
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Doane TL, Burda C. The unique role of nanoparticles in nanomedicine: imaging, drug delivery and therapy. Chem Soc Rev 2012; 41:2885-911. [DOI: 10.1039/c2cs15260f] [Citation(s) in RCA: 857] [Impact Index Per Article: 71.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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293
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Bringas E, Köysüren Ö, Quach DV, Mahmoudi M, Aznar E, Roehling JD, Marcos MD, Martínez-Máñez R, Stroeve P. Triggered release in lipid bilayer-capped mesoporous silica nanoparticles containing SPION using an alternating magnetic field. Chem Commun (Camb) 2012; 48:5647-9. [DOI: 10.1039/c2cc31563g] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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294
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Lee J, Kim H, Kim S, Lee H, Kim J, Kim N, Park HJ, Choi EK, Lee JS, Kim C. A multifunctional mesoporous nanocontainer with an iron oxide core and a cyclodextrin gatekeeper for an efficient theranostic platform. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32137h] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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295
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Ding J, Kong X, Yao J, Wang J, Cheng X, Tang B, He Z. Core–shell mesoporous silica nanoparticles improve HeLa cell growth and proliferation inhibition by (−)-epigallocatechin-3-gallate by prolonging the half-life. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32271d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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296
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297
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Coskun A, Spruell JM, Barin G, Dichtel WR, Flood AH, Botros YY, Stoddart JF. High hopes: can molecular electronics realise its potential? Chem Soc Rev 2012; 41:4827-59. [PMID: 22648395 DOI: 10.1039/c2cs35053j] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Ali Coskun
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
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298
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Fernandes A, Hensenne P, Mathy B, Guo W, Nysten B, Jonas AM, Riant O. Increased Catalytic Activity of Surface-Immobilized Palladium Complexes in the Fluorogenic Deprotection of an Alloc-Derivatized Coumarin. Chemistry 2011; 18:788-92. [DOI: 10.1002/chem.201102245] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Indexed: 11/11/2022]
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299
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Malti WE, Mongin O, Blanchard-Desce M, Raehm L, Durand JO. Functionalisation of mesoporous silica nanoparticles with 3-isocynatopropyltrichlorosilane. CR CHIM 2011. [DOI: 10.1016/j.crci.2011.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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300
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Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry. Proc Natl Acad Sci U S A 2011; 108:20416-21. [PMID: 22135467 DOI: 10.1073/pnas.1109795108] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In donor-acceptor mechanically interlocked molecules that exhibit bistability, the relative populations of the translational isomers--present, for example, in a bistable [2]rotaxane, as well as in a couple of bistable [2]catenanes of the donor-acceptor vintage--can be elucidated by slow scan rate cyclic voltammetry. The practice of transitioning from a fast scan rate regime to a slow one permits the measurement of an intermediate redox couple that is a function of the equilibrium that exists between the two translational isomers in the case of all three mechanically interlocked molecules investigated. These intermediate redox potentials can be used to calculate the ground-state distribution constants, K. Whereas, (i) in the case of the bistable [2]rotaxane, composed of a dumbbell component containing π-electron-rich tetrathiafulvalene and dioxynaphthalene recognition sites for the ring component (namely, a tetracationic cyclophane, containing two π-electron-deficient bipyridinium units), a value for K of 10 ± 2 is calculated, (ii) in the case of the two bistable [2]catenanes--one containing a crown ether with tetrathiafulvalene and dioxynaphthalene recognition sites for the tetracationic cyclophane, and the other, tetrathiafulvalene and butadiyne recognition sites--the values for K are orders (one and three, respectively) of magnitude greater. This observation, which has also been probed by theoretical calculations, supports the hypothesis that the extra stability of one translational isomer over the other is because of the influence of the enforced side-on donor-acceptor interactions brought about by both π-electron-rich recognition sites being part of a macrocyclic polyether.
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