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Adams MC, Milam VT. Uncovering Molecular Quencher Effects on FRET Phenomena in Microsphere-Immobilized Probe Systems. Anal Chem 2023; 95:13796-13803. [PMID: 37651319 PMCID: PMC10515108 DOI: 10.1021/acs.analchem.3c01064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 08/10/2023] [Indexed: 09/02/2023]
Abstract
Double-stranded (ds) oligonucleotide probes composed of quencher-dye sequence pairs outperform analogous single-stranded (ss) probes due to their superior target sequence specificity without any prerequisite target labeling. Optimizing sequence combinations for dsprobe design requires promoting a fast, accurate response to a specific target sequence while minimizing spontaneous dsprobe dissociation events. Here, flow cytometry is used to rapidly interrogate the stability and selective responsiveness of 20 candidate LNA and DNA dsprobes to a 24 base-long segment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA and ∼243 degenerate RNA sequences serving as model variants. Importantly, in contrast to quantifying binding events of dye-labeled targets via flow cytometry, the current work employs the Förster resonance energy transfer (FRET)-based detection of unlabeled RNA targets. One DNA dsprobe with a 15-base-long hybridization partner containing a central abasic site emerged as very stable yet responsive only to the SARS-CoV-2 RNA segment. Separate displacement experiments, however, indicated that ∼12% of these quencher-capped hybridization partners remain bound, even in the presence of an excess SARS-CoV-2 RNA target. To examine their quenching range, additional titration studies varied the ratios and spatial placement of nonquencher and quencher-capped hybridization partners in the dsprobes. These titration studies indicate that these residual, bound quencher-capped partners, even at low percentages, act as nodes, enabling both static quenching effects within each residual dsprobe as well as longer-range quenching effects on neighboring FAM moieties. Overall, these studies provide insight into practical implications for rapid dsprobe screening and target detection by combining flow cytometry with FRET-based detection.
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Affiliation(s)
- Mary Catherine Adams
- School
of Materials Science and Engineering, Parker H. Petit Institute for Bioengineering, Bioscience Georgia Institute of Technology, 771 Ferst Drive NW, Atlanta, Georgia 30332-0245 United States
| | - Valeria T. Milam
- School
of Materials Science and Engineering, Parker H. Petit Institute for Bioengineering, Bioscience Georgia Institute of Technology, 771 Ferst Drive NW, Atlanta, Georgia 30332-0245 United States
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Eze NA, Milam VT. Quantitative Analysis of In Situ Locked Nucleic Acid and DNA Competitive Displacement Events on Microspheres. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6871-6881. [PMID: 35617467 DOI: 10.1021/acs.langmuir.2c00220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Synthetic analogues of natural oligonucleotides known as locked nucleic acids (LNAs) offer superior nuclease resistance and cytocompatibility for numerous scenarios ranging from in vitro detection to intracellular imaging of nucleic acids. While recognized as stronger hybridization partners than equivalent DNA residues, quantitative analysis of LNA hybridization activity is lacking, especially with respect to competitive displacement of the original hybridization partner by another oligonucleotide. In the current study, we perform in situ measurements of toehold-mediated competitive displacement of soluble, fluorescently labeled primary targets from probe strands immobilized on microspheres using high throughput flow cytometry. Both LNA-DNA hybrid sequences and pure DNA sequences are employed as the immobilized strands, as soluble, fluorescently labeled 9-base-long primary targets, and as unlabeled 15-base-long secondary or competitive targets. In addition to comparing chemically substituted and unsubstituted sequences, we explore the effects of mismatched primary targets and the location of the toehold segment within the primary duplexes on the resulting displacement profiles. The primary duplex or double-stranded probe (dsprobe) systems implemented here exhibited varying responses to unlabeled secondary targets ranging from surprisingly modest primary target displacement activity despite the presence of a six base-long nucleotide toehold segment at the dsprobe free end to distinctive displacement profiles sensitive to LNA substitutions and the placement of the toehold segment closer to the microsphere surface.
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Abstract
Hybridization between nucleic acid strands immobilized on a solid support with partners in solution is widely practiced in bioanalytical technologies and materials science. An important fundamental aspect of understanding these reactions is the role played by immobilization in the dynamics of duplex formation and disassembly. This report reviews and analyzes literature kinetic data to identify commonly observed trends and to correlate them with probable molecular mechanisms. The analysis reveals that while under certain conditions impacts from immobilization are minimal so that surface and solution hybridization kinetics are comparable, it is more typical to observe pronounced offsets between the two scenarios. In the forward (hybridization) direction, rates at the surface commonly decrease by one to two decades relative to solution, while in the reverse direction rates of strand separation at the surface can exceed those in solution by tens of decades. By recasting the deviations in terms of activation barriers, a consensus of how immobilization impacts nucleation, zipping, and strand separation can be conceived within the classical mechanism in which duplex formation is rate limited by preassembly of a nucleus a few base pairs in length, while dehybridization requires the cumulative breakup of base pairs along the length of a duplex. Evidence is considered for how excess interactions encountered on solid supports impact these processes.
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Affiliation(s)
- Eshan Treasurer
- Department of Chemical and Biomolecular Engineering, New York University Tandon School of Engineering, Brooklyn, New York 11201, United States
| | - Rastislav Levicky
- Department of Chemical and Biomolecular Engineering, New York University Tandon School of Engineering, Brooklyn, New York 11201, United States
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Ochoa S, Milam VT. Modified Nucleic Acids: Expanding the Capabilities of Functional Oligonucleotides. Molecules 2020; 25:E4659. [PMID: 33066073 PMCID: PMC7587394 DOI: 10.3390/molecules25204659] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/07/2020] [Accepted: 10/08/2020] [Indexed: 12/20/2022] Open
Abstract
In the last three decades, oligonucleotides have been extensively investigated as probes, molecular ligands and even catalysts within therapeutic and diagnostic applications. The narrow chemical repertoire of natural nucleic acids, however, imposes restrictions on the functional scope of oligonucleotides. Initial efforts to overcome this deficiency in chemical diversity included conservative modifications to the sugar-phosphate backbone or the pendant base groups and resulted in enhanced in vivo performance. More importantly, later work involving other modifications led to the realization of new functional characteristics beyond initial intended therapeutic and diagnostic prospects. These results have inspired the exploration of increasingly exotic chemistries highly divergent from the canonical nucleic acid chemical structure that possess unnatural physiochemical properties. In this review, the authors highlight recent developments in modified oligonucleotides and the thrust towards designing novel nucleic acid-based ligands and catalysts with specifically engineered functions inaccessible to natural oligonucleotides.
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Affiliation(s)
- Steven Ochoa
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Valeria T. Milam
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA;
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Lanfranco R, Jana PK, Tunesi L, Cicuta P, Mognetti BM, Di Michele L, Bruylants G. Kinetics of Nanoparticle-Membrane Adhesion Mediated by Multivalent Interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2002-2012. [PMID: 30636419 DOI: 10.1021/acs.langmuir.8b02707] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Multivalent adhesive interactions mediated by a large number of ligands and receptors underpin many biological processes, including cell adhesion and the uptake of particles, viruses, parasites, and nanomedical vectors. In materials science, multivalent interactions between colloidal particles have enabled unprecedented control over the phase behavior of self-assembled materials. Theoretical and experimental studies have pinpointed the relationship between equilibrium states and microscopic system parameters such as the ligand-receptor binding strength and their density. In regimes of strong interactions, however, kinetic factors are expected to slow down equilibration and lead to the emergence of long-lived out-of-equilibrium states that may significantly influence the outcome of self-assembly experiments and the adhesion of particles to biological membranes. Here we experimentally investigate the kinetics of adhesion of nanoparticles to biomimetic lipid membranes. Multivalent interactions are reproduced by strongly interacting DNA constructs, playing the role of both ligands and receptors. The rate of nanoparticle adhesion is investigated as a function of the surface density of membrane-anchored receptors and the bulk concentration of nanoparticles and is observed to decrease substantially in regimes where the number of available receptors is limited compared to the overall number of ligands. We attribute such peculiar behavior to the rapid sequestration of available receptors after initial nanoparticle adsorption. The experimental trends and the proposed interpretation are supported by numerical simulations.
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Affiliation(s)
- Roberta Lanfranco
- Biological and Soft Systems, Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , United Kingdom
- Université Libre de Bruxelles (ULB) , Engineering of Molecular NanoSystems , 50 av. F.D. Roosevelt , 1050 Brussels , Belgium
| | - Pritam Kumar Jana
- Université Libre de Bruxelles (ULB) , Interdisciplinary Center for Nonlinear Phenomena and Complex Systems, Campus Plaine , CP 231, Blvd. du Triomphe , B-1050 Brussels , Belgium
| | - Lucia Tunesi
- Biological and Soft Systems, Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , United Kingdom
| | - Pietro Cicuta
- Biological and Soft Systems, Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , United Kingdom
| | - Bortolo Matteo Mognetti
- Université Libre de Bruxelles (ULB) , Interdisciplinary Center for Nonlinear Phenomena and Complex Systems, Campus Plaine , CP 231, Blvd. du Triomphe , B-1050 Brussels , Belgium
| | - Lorenzo Di Michele
- Biological and Soft Systems, Cavendish Laboratory , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , United Kingdom
| | - Gilles Bruylants
- Université Libre de Bruxelles (ULB) , Engineering of Molecular NanoSystems , 50 av. F.D. Roosevelt , 1050 Brussels , Belgium
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