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Asai N, Schmidt K, Aktuğ G, Fossati S, Sladek J, Lynn NS, Dostalek J. Tethered Catalytic Hairpin Assembly with Plasmon-Enhanced Fluorescence Readout for Single Molecule Detection. SMALL METHODS 2025:e2500037. [PMID: 40207774 DOI: 10.1002/smtd.202500037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2025] [Revised: 03/23/2025] [Indexed: 04/11/2025]
Abstract
Here a novel digital bioassay readout concept is reported that does not rely on enzymatic amplification nor compartmenting of an analyzed liquid sample. Rather, it is based on counting individual affinity-captured target biomolecules via the use of a tethered catalytic hairpin assembly (tCHA) deployed on a solid sensor surface with spatial confinement utilized by a flexible polymer linker (FPL). Wide-field plasmon-enhanced fluorescence (PEF) imaging is employed for optical real-time probing of the reaction kinetics, where affinity-captured target molecules are manifested as spatially distinct bright fluorescent spots. The effect of the length of the FPLs is investigated, and the analytical performance of the dual amplification tCHA-PEF concept is tested by using a model short single-stranded DNA analyte. When applied in a sandwich immunoassay, the detection of target proteins at sub-femtomolar concentrations is demonstrated. The reported experiments are supported by diffusion-limited mass transfer models and document the potential of tCHA-PEF as a new class of generic enzyme-free bioanalytical tools enabling the ultrasensitive analysis of trace amounts of protein and nucleic acid analytes, making it attractive for future molecular diagnostics and research applications.
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Affiliation(s)
- Naoto Asai
- LiST - Laboratory for Life Sciences and Technology, Danube Private University, Viktor Kaplan-Straße 2, Wiener Neustadt, 2700, Austria
| | - Katharina Schmidt
- LiST - Laboratory for Life Sciences and Technology, Danube Private University, Viktor Kaplan-Straße 2, Wiener Neustadt, 2700, Austria
| | - Gizem Aktuğ
- FZU-Institute of Physics, Czech Academy of Sciences, Na Slovance 2, Prague, 182 21, Czech Republic
- Faculty of Mathematics and Physics, Charles University, Prague, 121 16, Czech Republic
| | - Stefan Fossati
- FZU-Institute of Physics, Czech Academy of Sciences, Na Slovance 2, Prague, 182 21, Czech Republic
| | - Juraj Sladek
- FZU-Institute of Physics, Czech Academy of Sciences, Na Slovance 2, Prague, 182 21, Czech Republic
| | - N Scott Lynn
- FZU-Institute of Physics, Czech Academy of Sciences, Na Slovance 2, Prague, 182 21, Czech Republic
| | - Jakub Dostalek
- LiST - Laboratory for Life Sciences and Technology, Danube Private University, Viktor Kaplan-Straße 2, Wiener Neustadt, 2700, Austria
- FZU-Institute of Physics, Czech Academy of Sciences, Na Slovance 2, Prague, 182 21, Czech Republic
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Cheng P, Ferrell N, Hus SM, Moehring NK, Coupin MJ, Warner J, Li AP, Fissell WH, Kidambi PR. Protein-Enabled Size-Selective Defect-Sealing of Atomically Thin 2D Membranes for Dialysis and Nanoscale Separations. NANO LETTERS 2025; 25:193-203. [PMID: 39714067 PMCID: PMC11719630 DOI: 10.1021/acs.nanolett.4c04706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2024] [Revised: 11/25/2024] [Accepted: 11/26/2024] [Indexed: 12/24/2024]
Abstract
Atomically thin 2D materials present the potential for advancing membrane separations via a combination of high selectivity (from molecular sieving) and high permeance (due to atomic thinness). However, the creation of a high density of precise nanopores (narrow-size-distribution) over large areas in 2D materials remains challenging, and nonselective leakage from nanopore heterogeneity adversely impacts performance. Here, we demonstrate protein-enabled size-selective defect sealing (PDS) for atomically thin graphene membranes over centimeter scale areas by leveraging the size and reactivity of permeating proteins to preferentially seal larger nanopores (≥4 nm) while preserving a significant amount of smaller nanopores (via steric hindrance). Our defect-sealed nanoporous atomically thin membranes (NATMs) show stability up to ∼35 days during size-selective diffusive separations with a model dialysis biomolecule fluorescein isothiocyanate (FITC)-Ficoll 70 in phosphate buffer saline (PBS) solution as well as outperform state-of-the-art commercially available dialysis membranes (molecular-weight-cutoff ∼3.5-5 kDa and ∼8-10 kDa) with significantly higher permeance for smaller solutes KCl (∼0.66 nm) ∼5.1-6 × 10-5 ms-1 and vitamin B12 (B12, ∼1.5 nm) ∼2.8-4 × 10-6 ms-1 compared to small protein lysozyme (Lz, ∼4 nm) ∼4-6.4 × 10-8 m s-1, thereby allowing unprecedented selectivity for B12/Lz ∼70 and KCl/Lz ∼1280. Our work introduces proteins as nanoscale tools for size-selective defect sealing in atomically thin membranes to overcome persistent issues and advance separations for dialysis, protein desalting, small molecule separations/purification, and other bioprocesses.
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Affiliation(s)
- Peifu Cheng
- Department
of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Nicholas Ferrell
- Division
of Nephrology, Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio 43210, United States
| | - Saban M. Hus
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Nicole K. Moehring
- Interdisciplinary
Materials Science Program, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Matthew J. Coupin
- Walker
Department of Mechanical Engineering, University
of Texas at Austin, Austin, Texas 78712-1591, United States
| | - Jamie Warner
- Walker
Department of Mechanical Engineering, University
of Texas at Austin, Austin, Texas 78712-1591, United States
| | - An-Ping Li
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - William H. Fissell
- Department
of Medicine and Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
- Vanderbilt
Institute of Nanoscale Sciences and Engineering, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Piran R. Kidambi
- Department
of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37212, United States
- Interdisciplinary
Materials Science Program, Vanderbilt University, Nashville, Tennessee 37212, United States
- Vanderbilt
Institute of Nanoscale Sciences and Engineering, Vanderbilt University, Nashville, Tennessee 37212, United States
- Walker
Department of Mechanical Engineering, University
of Texas at Austin, Austin, Texas 78712-1591, United States
- Department
of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37212, United States
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Adamczyk O, Szota M, Rakowski K, Prochownik M, Doveiko D, Chen Y, Jachimska B. Bovine Serum Albumin as a Platform for Designing Biologically Active Nanocarriers-Experimental and Computational Studies. Int J Mol Sci 2023; 25:37. [PMID: 38203208 PMCID: PMC10778598 DOI: 10.3390/ijms25010037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
Due to the specificity of their structure, protein systems are adapted to carry various ligands. The structure of many proteins potentially allows for two types of immobilization of a therapeutic agent, either on the outer surface of the protein or within the protein structure. The existence of two active sites in BSA's structure, the so-called Sudlow I and II, was confirmed. The conducted research involved determining the effectiveness of BSA as a potential carrier of 5-fluorouracil (5FU). 5-fluorouracil is a broad-spectrum anticancer drug targeting solid tumors. The research was carried out to estimate the physicochemical properties of the system using complementary measurement techniques. The optimization of the complex formation conditions made it possible to obtain significant correlations between the form of the drug and the effective localization of the active substance in the structure of the protein molecule. The presence of two amino groups in the 5FU structure contributes to the deprotonation of the molecule at high pH values (pH > 8) and the transition to the anionic form (AN1 and AN3). To investigate the binding affinity of the tautomeric form with BSA, UV-vis absorption, fluorescence quenching, zeta potential, QCM-D, and CD spectroscopic studies were performed. The experimental research was supported by molecular dynamics (MD) simulations and molecular docking. The simulations confirm the potential location of 5FU tautomers inside the BSA structure and on its surface.
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Affiliation(s)
- Olga Adamczyk
- Department of Physics, Cracow University of Technology, 30-084 Krakow, Poland (M.P.)
| | - Magdalena Szota
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, 31-355 Krakow, Poland (K.R.)
| | - Kamil Rakowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, 31-355 Krakow, Poland (K.R.)
| | - Magdalena Prochownik
- Department of Physics, Cracow University of Technology, 30-084 Krakow, Poland (M.P.)
| | - Daniel Doveiko
- Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK; (D.D.); (Y.C.)
| | - Yu Chen
- Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK; (D.D.); (Y.C.)
| | - Barbara Jachimska
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, 31-355 Krakow, Poland (K.R.)
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