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Yang B, Gordiyenko K, Schäfer A, Dadfar SMM, Yang W, Riehemann K, Kumar R, Niemeyer CM, Hirtz M. Fluorescence Imaging Study of Film Coating Structure and Composition Effects on DNA Hybridization. ADVANCED NANOBIOMED RESEARCH 2023. [DOI: 10.1002/anbr.202200133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Bingquan Yang
- Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMFi) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Klavdiya Gordiyenko
- Institute of Biological Interfaces (IBG-1) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Andreas Schäfer
- nanoAnalytics GmbH Heisenbergstraße 11 48149 Münster Germany
| | - Seyed Mohammad Mahdi Dadfar
- Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMFi) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Wenwu Yang
- Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMFi) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Kristina Riehemann
- Physical Institute and Center for Nanotechnology (CeNTech) University of Münster Wilhelm-Klemm-Straße 10 48149 Münster Germany
| | - Ravi Kumar
- Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMFi) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Christof M. Niemeyer
- Institute of Biological Interfaces (IBG-1) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Michael Hirtz
- Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMFi) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
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2
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Movilli J, Choudhury SS, Schönhoff M, Huskens J. Enhancement of Probe Density in DNA Sensing by Tuning the Exponential Growth Regime of Polyelectrolyte Multilayers. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2020; 32:9155-9166. [PMID: 33191977 PMCID: PMC7659331 DOI: 10.1021/acs.chemmater.0c02454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Surface-based biosensing devices benefit from a dedicated design of the probe layer present at the transducing interface. The layer architecture, its physicochemical properties, and the embedding of the receptor sites affect the probability of binding the analyte. Here, the enhancement of the probe density at the sensing interface by tuning the exponential growth regime of polyelectrolyte multilayers (PEMs) is presented. PEMs were made of poly-l-lysine (PLL), with appended clickable dibenzocyclooctyne (DBCO) groups and oligo(ethylene glycol) chains, and poly(styrene sulfonate) (PSS). The DNA probe loading and target hybridization efficiencies of the PEMs were evaluated as a function of the PLL layer number and the growth regime by a quartz crystal microbalance (QCM). An amplification factor of 25 in the target DNA detection was found for a 33-layer exponentially grown PEM compared to a monolayer. A Voigt-based model showed that DNA probe binding to the DBCO groups is more efficient in the open, exponentially grown films, while the hybridization efficiencies appeared to be high for all layer architectures. These results show the potential of such engineered gel-like structures to increase the detection of bio-relevant analytes in biosensing systems.
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Affiliation(s)
- Jacopo Movilli
- Molecular
NanoFabrication group, MESA+ Institute for Nanotechnology, Faculty
of Science and Technology, University of
Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Salmeen Shakil Choudhury
- Molecular
NanoFabrication group, MESA+ Institute for Nanotechnology, Faculty
of Science and Technology, University of
Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Monika Schönhoff
- Institute
of Physical Chemistry, and Center for Soft Nanoscience, University of Münster, Corrensstr. 28/30, 48149 Münster, Germany
| | - Jurriaan Huskens
- Molecular
NanoFabrication group, MESA+ Institute for Nanotechnology, Faculty
of Science and Technology, University of
Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
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3
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Papadakis G, Palladino P, Chronaki D, Tsortos A, Gizeli E. Sample-to-answer acoustic detection of DNA in complex samples. Chem Commun (Camb) 2017; 53:8058-8061. [DOI: 10.1039/c6cc10175e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The present study demonstrates the sensitive and label-free acoustic detection of dsDNA amplicons produced from whole Salmonella Thyphimurium cells without employing any DNA extraction and/or purification step, in the presence of the lysed bacterial cells and in a hybridization-free assay.
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Affiliation(s)
- George Papadakis
- Institute of Molecular Biology and Biotechnology-FORTH
- Heraklion
- Greece
| | | | - Dimitra Chronaki
- Institute of Molecular Biology and Biotechnology-FORTH
- Heraklion
- Greece
- Dept. of Biology
- Univ. of Crete
| | - Achilleas Tsortos
- Institute of Molecular Biology and Biotechnology-FORTH
- Heraklion
- Greece
| | - Electra Gizeli
- Institute of Molecular Biology and Biotechnology-FORTH
- Heraklion
- Greece
- Dept. of Biology
- Univ. of Crete
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4
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Su Q, Wesner D, Schönherr H, Nöll G. Molecular beacon modified sensor chips for oligonucleotide detection with optical readout. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:14360-14367. [PMID: 25363421 DOI: 10.1021/la504105x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Three different surface bound molecular beacons (MBs) were investigated using surface plasmon fluorescence spectroscopy (SPFS) as an optical readout technique. While MB1 and MB2, both consisting of 36 bases, differed only in the length of the linker for surface attachment, the significantly longer MB3, consisting of 56 bases, comprised an entirely different sequence. For sensor chip preparation, the MBs were chemisorbed on gold via thiol anchors together with different thiol spacers. The influence of important parameters, such as the length of the MBs, the length of the linker between the MBs and the gold surface, the length and nature of the thiol spacers, and the ratio between the MBs and the thiol spacers was studied. After hybridization with the target, the fluorophore of the longer MB3 was oriented close to the surface, and the shorter MBs were standing more or less upright, leading to a larger increase in fluorescence intensity. Fluorescence microscopy revealed a homogeneous distribution of the MBs on the surface. The sensor chips could be used for simple and fast detection of target molecules with a limit of detection in the larger picomolar range. The response time was between 5 and 20 min. Furthermore, it was possible to distinguish between fully complementary and singly mismatched targets. While rinsing with buffer solution after hybridization with target did not result in any signal decrease, complete dehybridization could be carried out by intense rinsing with pure water. The MB modified sensor chips could be prepared in a repeatable manner and reused many times without significant decrease in performance.
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Affiliation(s)
- Qiang Su
- Nöll Junior Research Group, Organic Chemistry, Department of Chemistry and Biology, Faculty IV, Siegen University , Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany
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Structural Behavior of Au-Calf Thymus DNA Interface Estimated Through an Electrochemical Impedance Spectroscopy and Surface Plasmon Resonance Study. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.02.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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6
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Lai SL, Yang KL. Detecting DNA targets through the formation of DNA/CTAB complex and its interactions with liquid crystals. Analyst 2011; 136:3329-34. [PMID: 21738932 DOI: 10.1039/c1an15173h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper, we report the formation of a DNA/cetyl trimethylammonium bromide (CTAB) complex on a solid surface and its interaction with a thin layer of liquid crystals (LC) supported on the surface. Our results show that when the surface is decorated with DNA only, the LC gives a bright image, but when the surface is decorated with the DNA/CTAB complex, the LC becomes dark when the surface density of CTAB is above 5.25 ± 0.13 × 10(13)/cm(2). To exploit this phenomenon for detecting DNA targets, we used a surface decorated with electroneutral PNA probes for capturing DNA targets, and then treated the surface with 0.1 mM of CTAB. In the presence of DNA targets, a PNA/DNA/CTAB complex is formed and that leads to a dark image on the thin layer of the LC supported on the surface. Moreover, DNA targets with a complementary, 1-base mismatch and non-complementary sequence can be differentiated by using this method. This study provides a new principle for the label-free detection of DNA targets without any fluorescent labels.
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Affiliation(s)
- Siok Lian Lai
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576
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7
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Hafner AM, Corthésy B, Textor M, Merkle HP. Tuning the immune response of dendritic cells to surface-assembled poly(I:C) on microspheres through synergistic interactions between phagocytic and TLR3 signaling. Biomaterials 2011; 32:2651-61. [PMID: 21216459 DOI: 10.1016/j.biomaterials.2010.12.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 12/14/2010] [Indexed: 12/14/2022]
Abstract
The artificial dsRNA polyriboinosinic acid-polyribocytidylic acid, poly(I:C), is a potent adjuvant candidate for vaccination, as it strongly drives cell-mediated immunity. However, because of its effects on non-immune bystander cells, poly(I:C) administration may bear danger for the development of autoimmune diseases. Thus poly(I:C) should be applied in the lowest dose possible. We investigated microspheres carrying surface-assembled poly(I:C) as a two-in-one adjuvant formulation to stimulate maturation of monocyte-derived dendritic cells (MoDCs). Negatively charged polystyrene microspheres were equipped with a poly(ethylene glycol) corona through electrostatically driven surface assembly of a library of polycationic poly(l-lysine)-graft-poly(ethylene glycol) copolymers, PLL-g-PEG. Stable surface assembly of poly(I:C) was achieved by incubation of polymer-coated microspheres in an aqueous poly(I:C) solution. Surface-assembled poly(I:C) exhibited a strongly enhanced efficacy to stimulate maturation of MoDCs by up to two orders of magnitude, as compared to free poly(I:C). Multiple phagocytosis events were the key factor to enhance the efficacy. The cytokine secretion pattern of MoDCs after exposure to surface-assembled poly(I:C) differed from that of free poly(I:C), while their ability to stimulate T cell proliferation was similar. Overall, phagocytic signaling plays an important role in defining the resulting immune response to such two-in-one adjuvant formulations.
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Affiliation(s)
- Annina M Hafner
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich 8093, Switzerland
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8
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Schreiner SM, Shudy DF, Hatch AL, Opdahl A, Whitman LJ, Petrovykh DY. Controlled and efficient hybridization achieved with DNA probes immobilized solely through preferential DNA-substrate interactions. Anal Chem 2010; 82:2803-10. [PMID: 20196546 DOI: 10.1021/ac902765g] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Quantitative and reproducible data can be obtained from surface-based DNA sensors if variations in the conformation and surface density of immobilized single-stranded DNA capture probes are minimized. Both the conformation and surface density can be independently and deterministically controlled by taking advantage of the preferential adsorption of adenine nucleotides (dA) on gold, as previously demonstrated using a model system in Opdahl, A.; Petrovykh, D. Y.; Kimura-Suda, H.; Tarlov, M. J.; Whitman, L. J. Proc. Natl. Acad. Sci. U.S.A. 2007, 104, 9-14. Here, we describe the immobilization and subsequent hybridization properties of a 15-nucleotide DNA probe sequence that has additional m adenine nucleotides, (dA)(m), at the 5' end. Quantitative analysis of immobilization and hybridization for these probes indicates that the (dA)(m) block preferentially adsorbs on gold, forcing the probe portion of the strand to adopt an upright conformation suited for efficient hybridization. In addition, a wide range of probe-to-probe lateral spacing can be achieved by coimmobilizing the probe DNA with a lateral spacer, a strand of k adenine nucleotides, (dA)(k). Altering either the length or relative concentration of the (dA)(k) spacers added during probe immobilization controls the average surface density of probes; the density of probes, in turn, systematically modulates their hybridization with solution targets.
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Affiliation(s)
- Sarah M Schreiner
- Department of Chemistry, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA
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9
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Du M, Yang T, Zhang Y, Jiao K. Sensitively Electrochemical Sensing for Sequence-Specific Detection of Phosphinothricin Acetyltransferase Gene: Layer-by-Layer Films of Poly-L-Lysine and Au-Carbon Nanotube Hybrid. ELECTROANAL 2009. [DOI: 10.1002/elan.200900187] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Saini G, Gates R, Asplund MC, Blair S, Attavar S, Linford MR. Directing polyallylamine adsorption on microlens array patterned silicon for microarray fabrication. LAB ON A CHIP 2009; 9:1789-1796. [PMID: 19495464 DOI: 10.1039/b900748m] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The selective adsorption of reagents is often essential for bioarray and lab-on-a-chip type devices. As the starting point for a bioarray, alkyl monolayer terminated silicon shards were photopatterned in a few nanoseconds with thousands of wells (spots) using an optical element, a microlens array. Polyallylamine (PAAm), a primary amine containing polymer, adsorbed with little selectivity to the spots, i.e., silicon oxide, over the hydrophobic background. However, at appropriate concentrations, addition of a cationic surfactant to the PAAm deposition solution, cetyltrimethylammonium chloride, prevented the nonspecific adsorption of PAAm onto the hydrophobic monolayer, while directing it effectively to the active spots on the device. A nonionic surfactant was less effective in preventing the nonspecific adsorption of PAAm onto the hydrophobic monolayer. The localized reactions/interactions of adsorbed PAAm with four species that are useful for bioconjugate chemistry: glutaric anhydride, phenylenediisothiocyanate, biotin NHS ester, and an oligonucleotide (DNA) were shown in the spots of an array. The reactivity of PAAm was further demonstrated with an isocyanate. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) played an important role in confirming selective surface reactivity and adsorption. X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry, and wetting confirmed PAAm reactivity on planar substrates.
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Affiliation(s)
- Gaurav Saini
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
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11
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Das J, Huh CH, Kwon K, Park S, Jon S, Kim K, Yang H. Comparison of the nonspecific binding of DNA-conjugated gold nanoparticles between polymeric and monomeric self-assembled monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:235-241. [PMID: 19032023 DOI: 10.1021/la802531d] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The nonspecific binding of DNA-conjugated gold nanoparticles (AuNPs) to solid surfaces is more difficult to control than that of DNA molecules due to the more attractive interactions from the large number of DNA molecules per AuNP. This paper reports that the polymeric self-assembled monolayers (SAMs) formed on indium-tin oxide (ITO) electrodes significantly inhibit the nonspecific binding of DNA-conjugated AuNPs. The random copolymers used to prepare the polymeric SAMs consist of three functional parts: an ITO-reactive silane group, a DNA-blocking poly(ethylene glycol) (PEG) group, and an amine-reactive N-acryloxysuccinimide group. In order to compare the polymeric SAMs with various monomeric SAMs, the relative nonspecific binding of the DNA-conjugated AuNPs to the ITO electrodes modified with (3-aminopropyl)triethoxysilane (APTES), 3-aminopropylphosphonic acid, 3-phosphonopropionic acid, or 11-phosphonoundecanoic acid is examined by measuring the electrocatalytic anodic current of hydrazine caused by the nonspecifically absorbed AuNPs and by counting the AuNPs adsorbed onto modified ITO electrodes. Carboxylic-acid-terminated and amine-terminated monomeric SAMs cause high levels of nonspecific binding of DNA-conjugated AuNPs. The monomeric SAM modified with the carboxylic-acid-terminated poly(amidoamine) dendrimer shows low levels of nonspecific binding (2.0% nonspecific binding relative to APTES) due to the high surface density of the negative charge. The simply prepared polymeric SAM produces the lowest level of nonspecific binding (0.8% nonspecific binding relative to APTES), resulting from the combined effect of (i) DNA-blocking PEG and carboxylic acid groups and (ii) dense polymeric SAMs. Therefore, thin and dense polymeric SAMs may be effective in electrochemical detection and easy DNA immobilization along with low levels of nonspecific binding.
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Affiliation(s)
- Jagotamoy Das
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea
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12
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Lee L, Johnston APR, Caruso F. Manipulating the salt and thermal stability of DNA multilayer films via oligonucleotide length. Biomacromolecules 2008; 9:3070-8. [PMID: 18826323 DOI: 10.1021/bm800593t] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
DNA films are promising materials for diverse applications, including sensing, diagnostics, and drug/gene delivery. However, the ability to tune the stability of DNA films remains a crucial aspect for such applications. Herein, we examine the role of oligonucleotide length on the formation, and salt and thermal stability, of DNA multilayer films using oligonucleotides of homopolymeric diblocks (polyAG and polyTC), with each block (A, G, T, or C) ranging from 5 to 30 bases (10-, 20-, 30-, 40-, and 60-mer). Using a combination of quartz crystal microgravimetry, dual polarization interferometry, and flow cytometry, we demonstrate that at least 10 bases per hybridizing block in the DNA diblocks (that is, 20-mer) are required for successful hybridization and, hence, DNA multilayer film formation. Films assembled using longer oligonucleotide blocks were more stable in low salt conditions, with the DNA multilayer films assembled from the 60-mer oligonucleotides remaining intact in solutions of about 25 mM NaCl. A systematic increase in film melting temperature ( T m) was observed for the DNA multilayer films (assembled on colloids) with increasing oligonucleotide length, ranging from 38.5 degrees C for the 20-mer films to 53 degrees C for the 60-mer films. Further, an alternating trend in T m of the DNA multilayer films was observed with layer number (AG or TC); DNA multilayer films terminated with an AG layer exhibited a higher T m (44-49 degrees C) than films with an outermost TC layer (ca. 38 degrees C), suggesting a rearrangement of the film structure upon hybridization of the outermost layer. This work shows that the stability of DNA multilayer films can be tuned by varying the length of the oligonucleotide building blocks, thus providing a versatile means to tailor the salt and thermal stability of DNA films, which is necessary for the application of such films.
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Affiliation(s)
- Lillian Lee
- Centre for Nanoscience and Nanotechnology, Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria 3010, Australia
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13
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Chen L, Rengifo HR, Grigoras C, Li X, Li Z, Ju J, Koberstein JT. Spin-On End-Functional Diblock Copolymers for Quantitative DNA Immobilization. Biomacromolecules 2008; 9:2345-52. [DOI: 10.1021/bm800258g] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lu Chen
- Columbia University Department of Chemical Engineering 500 West 120th Street, New York, New York 10027, and Columbia Genome Center, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Hernán R. Rengifo
- Columbia University Department of Chemical Engineering 500 West 120th Street, New York, New York 10027, and Columbia Genome Center, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Cristian Grigoras
- Columbia University Department of Chemical Engineering 500 West 120th Street, New York, New York 10027, and Columbia Genome Center, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Xiaoxu Li
- Columbia University Department of Chemical Engineering 500 West 120th Street, New York, New York 10027, and Columbia Genome Center, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Zengmin Li
- Columbia University Department of Chemical Engineering 500 West 120th Street, New York, New York 10027, and Columbia Genome Center, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Jingyue Ju
- Columbia University Department of Chemical Engineering 500 West 120th Street, New York, New York 10027, and Columbia Genome Center, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Jeffrey T. Koberstein
- Columbia University Department of Chemical Engineering 500 West 120th Street, New York, New York 10027, and Columbia Genome Center, Columbia University College of Physicians and Surgeons, New York, New York 10032
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Rengifo HR, Chen L, Grigoras C, Ju J, Koberstein JT. "Click-functional" block copolymers provide precise surface functionality via spin coating. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:7450-7456. [PMID: 18558782 DOI: 10.1021/la800038j] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
There are few existing methods for the quantitative functionalization of surfaces, especially for polymeric substrates. We demonstrate that alkyne end-functional diblock copolymers can be used to provide precise areal densities of reactive functionality on both hard (e.g., glass and silicon oxide) and soft (i.e., polymeric) substrates. Alkyne functionality is extremely versatile because the resultant functional surfaces are reactive toward azide functional molecules by Sharpless click chemistry. Spin-coated films of alpha-alkyne-omega-Br-poly( tert-butylacrylate- b-methylmethacrylate) (poly( tBA-MMA)) spontaneously self-assemble on the aforementioned substrates to present a surface monolayer of PtBA with a thickness in the range of 1 to 9 nm. The PMMA block physisorbs to provide multivalent anchoring onto hard substrates and is fixed onto polymer surfaces by interpenetration with the substrate polymer. The areal density of alkyne functional groups is precisely controlled by adjusting the thickness of the block copolymer monolayer, which is accomplished by changing either the spin coating conditions (i.e., rotational speed and solution concentration) or the copolymer molecular weight. The reactivity of surface-bound alkynes, in 1,3-dipolar cycloaddition reactions or by so-called "click chemistry", is demonstrated by covalent surface immobilization of fluorescently labeled azides. The modificed surfaces are characterized by atomic force microscopy (AFM), contact angle, ellipsometry, fluorescent imaging and angle-dependent X-ray photoelectron spectroscopy (ADXPS) measurements. Microarrays of covalently bound fluorescent molecules are created to demonstrate the approach and their performance is evaluated by determining their fluorescence signal-to-noise ratios.
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Affiliation(s)
- Hernán R Rengifo
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, MC4721, New York, New York 10027, USA
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15
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A DNA electrochemical sensor with poly-l-lysine/single-walled carbon nanotubes films and its application for the highly sensitive EIS detection of PAT gene fragment and PCR amplification of NOS gene. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2007.11.015] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Nagasaki Y, Kobayashi H, Katsuyama Y, Jomura T, Sakura T. Enhanced immunoresponse of antibody/mixed-PEG co-immobilized surface construction of high-performance immunomagnetic ELISA system. J Colloid Interface Sci 2007; 309:524-30. [PMID: 17368469 DOI: 10.1016/j.jcis.2006.12.079] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 12/15/2006] [Accepted: 12/15/2006] [Indexed: 10/23/2022]
Abstract
Poly(ethylene glycol) possessing pentaethylenehexamine at one end (N6-PEG) was prepared via a reductive amination reaction of aldehyde-ended PEG with pentaethylenehexamine. Using N6-PEG, an antibody/PEG co-immobilized surface was constructed on magnetic particles via an active ester reaction method. After immobilization of the antibody on the active ester surface, N6-PEG was reacted on the magnetic beads. A sandwich enzyme-linked immunosorbent assay (ELISA) system was newly constructed using PEG/antibody co-immobilized magnetic beads combined with an alkaline phosphatase (ALP)-assisted fluorescent detection system using alpha-fetoprotein (AFP) as a model antigen. The co-immobilization of both antibody and PEG on the magnetic bead surfaces reduced the nonspecific adsorption of proteins from cell lysates. Especially, when the magnetic particle surface was modified by N6-PEG mixtures with different molecular weights of 6000 and 2500 (6 kDa:2.5 kDa=9:1 w/w), the nonspecific adsorption of proteins was strongly suppressed. It is rather surprising for us that the sensitivity of the antibody on the surface was enhanced significantly when the PEG tethered chain was constructed in between the surface antibodies. Consequently, the mixed N6-PEG treatment showed a much higher S/N ratio than for the corresponding beads treated with bovine serum albumin (BSA), a conventional blocking reagent. Actually, when alpha-fetoprotein was analyzed by the magnetic bead-assisted ELISA thus constructed, the S/N ratio was about 20-fold higher for the mixed coating with PEG (6 kDa):PEG (2.5 kDa)=9:1, compared to the conventional BSA.
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Affiliation(s)
- Yukio Nagasaki
- Tsukuba Research Center for Interdisciplinary Materials Science, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8573, Japan.
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17
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Li Y, Wang Z, Ou LML, Yu HZ. DNA Detection on Plastic: Surface Activation Protocol To Convert Polycarbonate Substrates to Biochip Platforms. Anal Chem 2006; 79:426-33. [PMID: 17222004 DOI: 10.1021/ac061134j] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A mild and efficient surface activation protocol to convert polycarbonate (PC) substrates, e.g., plastic bases of compact disks, to biochip platforms for DNA probe immobilization and target detection is described. The preparation procedure (activation, patterning, and coupling) is simple and effective; the on-chip hybridization is sensitive and selective. Particularly, UV/ozone treatment of PC sheets produces a hydrophilic surface with a high density of reactive carboxylic acid groups [(4.8 +/- 0.2) x 10-10 mol/cm2] in less than 10 min at ambient conditions, and no significant aging or physical damage to the substrate is observed. Covalent immobilization of DNA probes via both passive (reagent-less photopatterning and coupling in bulk solution phase) and flow-through (creation of microarrays with microfluidic channel plates) procedures has been demonstrated. Subsequent hybridization shows uniform and strong fluorescent signals for complementary target DNA and allows clear discrimination between fully complementary targets and strands with a single base-pair mismatch. The surface chemistry described herein will facilitate the development of disposable plastic biochips (not limited to DNA microarrays) and the fabrication of biomedical devices that are readable with conventional optical drives.
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Affiliation(s)
- Yunchao Li
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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