1
|
Algar WR, Jeen T, Massey M, Peveler WJ, Asselin J. Small Surface, Big Effects, and Big Challenges: Toward Understanding Enzymatic Activity at the Inorganic Nanoparticle-Substrate Interface. Langmuir 2019; 35:7067-7091. [PMID: 30415548 DOI: 10.1021/acs.langmuir.8b02733] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Enzymes are important biomarkers for molecular diagnostics and targets for the action of drugs. In turn, inorganic nanoparticles (NPs) are of interest as materials for biological assays, biosensors, cellular and in vivo imaging probes, and vectors for drug delivery and theranostics. So how does an enzyme interact with a NP, and what are the outcomes of multivalent conjugation of its substrate to a NP? This invited feature article addresses the current state of the art in answering this question. Using gold nanoparticles (Au NPs) and semiconductor quantum dots (QDs) as illustrative materials, we discuss aspects of enzyme structure-function and the properties of NP interfaces and surface chemistry that determine enzyme-NP interactions. These aspects render the substrate-on-NP configurations far more complex and heterogeneous than the conventional turnover of discrete substrate molecules in bulk solution. Special attention is also given to the limitations of a standard kinetic analysis of the enzymatic turnover of these configurations, the need for a well-defined model of turnover, and whether a "hopping" model can account for behaviors such as the apparent acceleration of enzyme activity. A detailed and predictive understanding of how enzymes turn over multivalent NP-substrate conjugates will require a convergence of many concepts and tools from biochemistry, materials, and interface science. In turn, this understanding will help to enable rational, optimized, and value-added designs of NP bioconjugates for biomedical and clinical applications.
Collapse
Affiliation(s)
- W Russ Algar
- Department of Chemistry , University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T 1Z1 , Canada
| | - Tiffany Jeen
- Department of Chemistry , University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T 1Z1 , Canada
| | - Melissa Massey
- Department of Chemistry , University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T 1Z1 , Canada
| | - William J Peveler
- Department of Chemistry , University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T 1Z1 , Canada
- Division of Biomedical Engineering, School of Engineering , University of Glasgow , Glasgow G12 8LT , United Kingdom
| | - Jérémie Asselin
- Department of Chemistry , University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T 1Z1 , Canada
| |
Collapse
|
2
|
Kim H, Jeen T, Tran MV, Algar WR. Polyacrylamide gel electrophoresis of semiconductor quantum dots and their bioconjugates: materials characterization and physical insights from spectrofluorimetric detection. Analyst 2019; 143:1104-1116. [PMID: 29387848 DOI: 10.1039/c7an01581j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Colloidal semiconductor quantum dot (QD) nanocrystals have ideal fluorescence properties for bioanalysis and bioimaging, but these materials must be functionalized with an inorganic shell, organic ligand or polymer coating, and conjugated with biomolecules to be useful in such applications. Several different analytical techniques are used to characterize QDs and their multiple layers of functionalization. Here, we revisit poly(acrylamide) gel electrophoresis (PAGE), which has been scarcely used for the characterization of QDs and their bioconjugates in deference to the routine use of agarose gel electrophoresis. We implemented PAGE in a novel "stubby" capillary format with spectrofluorimetric detection, the combination of which enabled more rapid and more detailed characterization of QDs than was possible with both poly(acrylamide) and agarose slab gels. Correlations between the peak photoluminescence (PL) emission wavelength and electropherogram peaks, especially when combined with Ferguson analysis, provided new and significant insight into the key factors that determine the electrophoretic mobility of QDs, and helped to resolve heterogeneity and sub-populations in ensembles of QDs. The method was useful for characterization of the inorganic core/shell nanocrystals, their organic ligand and polymer coatings, and their final bioconjugates, the latter of which were in the form of peptide and protein conjugates. With further development and optimization, we anticipate that capillary PAGE with spectrofluorimetric detection will become a valuable addition to the toolbox of characterization techniques suitable for QDs, their bioconjugates, and other nanoparticle materials as well.
Collapse
Affiliation(s)
- Hyungki Kim
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.
| | | | | | | |
Collapse
|
3
|
Peveler WJ, Jia H, Jeen T, Rees K, Macdonald TJ, Xia Z, Chio WIK, Moorthy S, Parkin IP, Carmalt CJ, Algar WR, Lee TC. Cucurbituril-mediated quantum dot aggregates formed by aqueous self-assembly for sensing applications. Chem Commun (Camb) 2019; 55:5495-5498. [DOI: 10.1039/c9cc00410f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Supramolecular ‘gluing’ of quantum dots is demonstrated with cucurbituril and we present the opportunity to create molecular host–guest sensing schemes.
Collapse
Affiliation(s)
- William J. Peveler
- Division of Biomedical Engineering
- School of Engineering
- University of Glasgow
- Glasgow
- UK
| | - Hui Jia
- Institute for Materials Discovery
- University College London (UCL)
- UK
| | - Tiffany Jeen
- Department of Chemistry
- 2036 Main Mall
- University of British Columbia
- Vancouver
- Canada
| | - Kelly Rees
- Department of Chemistry
- 2036 Main Mall
- University of British Columbia
- Vancouver
- Canada
| | | | - Zhicheng Xia
- Department of Chemistry
- 2036 Main Mall
- University of British Columbia
- Vancouver
- Canada
| | - Weng-I Katherine Chio
- Institute for Materials Discovery
- University College London (UCL)
- UK
- Department of Chemistry
- University College London (UCL)
| | - Suresh Moorthy
- Institute for Materials Discovery
- University College London (UCL)
- UK
| | - Ivan P. Parkin
- Department of Chemistry
- University College London (UCL)
- London
- UK
| | | | - W. Russ Algar
- Department of Chemistry
- 2036 Main Mall
- University of British Columbia
- Vancouver
- Canada
| | - Tung-Chun Lee
- Institute for Materials Discovery
- University College London (UCL)
- UK
- Department of Chemistry
- University College London (UCL)
| |
Collapse
|
4
|
Affiliation(s)
- Tiffany Jeen
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - W. Russ Algar
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| |
Collapse
|
5
|
Clarke RM, Jeen T, Rigo S, Thompson JR, Kaake LG, Thomas F, Storr T. Exploiting exciton coupling of ligand radical intervalence charge transfer transitions to tune NIR absorption. Chem Sci 2017; 9:1610-1620. [PMID: 29675206 PMCID: PMC5887452 DOI: 10.1039/c7sc04537a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 12/18/2017] [Indexed: 12/03/2022] Open
Abstract
We detail the rational design of a series of bimetallic bis-ligand radical Ni salen complexes in which the relative orientation of the ligand radical chromophores provides a mechanism to tune the energy of intense intervalence charge transfer (IVCT) bands in the near infrared (NIR) region.
We detail the rational design of a series of bimetallic bis-ligand radical Ni salen complexes in which the relative orientation of the ligand radical chromophores provides a mechanism to tune the energy of intense intervalence charge transfer (IVCT) bands in the near infrared (NIR) region. Through a suite of experimental (electrochemistry, electron paramagnetic resonance spectroscopy, UV-vis-NIR spectroscopy) and theoretical (density functional theory) techniques, we demonstrate that bimetallic Ni salen complexes form bis-ligand radicals upon two-electron oxidation, whose NIR absorption energies depend on the geometry imposed in the bis-ligand radical complex. Relative to the oxidized monomer [1˙]+ (E = 4500 cm–1, ε = 27 700 M–1 cm–1), oxidation of the cofacially constrained analogue 2 to [2˙˙]2+ results in a blue-shifted NIR band (E = 4830 cm–1, ε = 42 900 M–1 cm–1), while oxidation of 5 to [5˙˙]2+, with parallel arrangement of chromophores, results in a red-shifted NIR band (E = 4150 cm–1, ε = 46 600 M–1 cm–1); the NIR bands exhibit double the intensity in comparison to the monomer. Oxidation of the intermediate orientations results in band splitting for [3˙˙]2+ (E = 4890 and 4200 cm–1; ε = 26 500 and 21 100 M–1 cm–1), and a red-shift for [4˙˙]2+ using ortho- and meta-phenylene linkers, respectively. This study demonstrates for the first time, the applicability of exciton coupling to ligand radical systems absorbing in the NIR region and shows that by simple geometry changes, it is possible to tune the energy of intense low energy absorption by nearly 400 nm.
Collapse
Affiliation(s)
- Ryan M Clarke
- Department of Chemistry , Simon Fraser University , V5A1S6 , Burnaby , BC , Canada .
| | - Tiffany Jeen
- Department of Chemistry , Simon Fraser University , V5A1S6 , Burnaby , BC , Canada .
| | - Serena Rigo
- Department of Chemistry , Simon Fraser University , V5A1S6 , Burnaby , BC , Canada .
| | - John R Thompson
- Department of Chemistry , Simon Fraser University , V5A1S6 , Burnaby , BC , Canada .
| | - Loren G Kaake
- Department of Chemistry , Simon Fraser University , V5A1S6 , Burnaby , BC , Canada .
| | - Fabrice Thomas
- Départment de Chimie Moléculaire - Chimie Inorganique Redox (CIRE) - UMR CNRS 5250 , Université Grenoble-Alpes , B.P. 53 , 38041 Grenoble Cedex 9 , France
| | - Tim Storr
- Department of Chemistry , Simon Fraser University , V5A1S6 , Burnaby , BC , Canada .
| |
Collapse
|
6
|
Petryayeva E, Jeen T, Algar WR. Optimization and Changes in the Mode of Proteolytic Turnover of Quantum Dot-Peptide Substrate Conjugates through Moderation of Interfacial Adsorption. ACS Appl Mater Interfaces 2017; 9:30359-30372. [PMID: 28846381 DOI: 10.1021/acsami.7b07519] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Enzymes have many important roles in biology and industry, and proteases are one of the most important classes of enzymes. Semiconductor quantum dots (QDs) are attractive materials for developing protease activity probes because of their advantageous physical and optical properties; however, interactions between a protease and a QD conjugated with its substrate can affect the turnover of that substrate. Here, we study the turnover of multivalent QD-peptide substrate conjugates as a function of multiple parameters: (i) the ligand coating on the QD, including dihydrolipoic acid (DHLA), glutathione (GSH), DHLA-poly(ethylene glycol) (DHLA-PEG), and DHLA-zwitterionic sulfobetaine (DHLA-SB); (ii) the identity of the protease, including trypsin, thrombin, and plasmin; and (iii) the number of substrate and nonsubstrate biomacromolecules conjugated per QD. We show that limiting protease adsorption on QDs is critical for optimizing the turnover of conjugated peptide substrates. Protease adsorption is inhibitory, and very strong adsorption leads to an apparent "scooting" mode of activity with limited turnover. In contrast, with weaker adsorption, enhancements in the turnover rate likely result from a "hopping" mode of activity. The putative hopping mode is thought to feature processive turnover of all substrates in multivalent conjugates with a rate-limiting step of diffusion between individual conjugates, and the magnitude of such enhancements increases with decreases in adsorption. Although it was possible to passivate DHLA- and GSH-coated QDs with high densities of conjugated biomacromolecules, the most effective strategy for reducing adsorption was the substitution of these ligands. Whereas passivation incrementally increased turnover, DHLA-PEG and DHLA-SB ligands converted the mode of turnover with plasmin from scooting to hopping and the DHLA-SB enhanced the turnover rates with thrombin and trypsin by approximately an order of magnitude relative to GSH ligands. The new insights from the broad scope of this study provide an important framework for designing optimized QD conjugates as probes and sensors for enzyme activity.
Collapse
Affiliation(s)
- Eleonora Petryayeva
- Department of Chemistry, University of British Columbia , 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Tiffany Jeen
- Department of Chemistry, University of British Columbia , 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - W Russ Algar
- Department of Chemistry, University of British Columbia , 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| |
Collapse
|