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Fernandes DA, Fernandes DD, Malik A, Gomes GNW, Appak-Baskoy S, Berndl E, Gradinaru CC, Kolios MC. Multifunctional nanoparticles as theranostic agents for therapy and imaging of breast cancer. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2021; 218:112110. [PMID: 33865007 DOI: 10.1016/j.jphotobiol.2020.112110] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 11/13/2020] [Accepted: 12/18/2020] [Indexed: 11/26/2022]
Abstract
Over the last decade, there has been significant developments in nanotechnology, in particular for combined imaging and therapeutic applications (theranostics). The core or shell of nanoemulsions (NEs) can be loaded with various therapeutic agents, including drugs with low solubility for effective treatment, or various imaging agents for specific imaging modalities (e.g., MRI, fluorescence). In this work, perfluorohexane (PFH) NEs were synthesized for theranostic applications and were coupled to silica coated gold nanoparticles (scAuNPs) to increase the generation of PFH bubbles upon laser induced vaporization (i.e., optical droplet vaporization). The localized heat generated from the absorption properties of these nanoparticles (used to provide photoacoustic signals) can also be used to treat cancer without significantly damaging nearby healthy tissues. The theranostic potential of these PFH-NEs for contrast imaging of tumors and as a drug-delivery vehicle for therapeutic purposes were demonstrated for both in vitro and in vivo systems using a combination of photoacoustic, ultrasound and fluorescence imaging modalities. The ability of PFH-NEs to couple with scAuNPs, attach to the membranes of cancer cells and internalize within cancer cells, are encouraging for targeted chemotherapeutic applications for directly inducing cancer cell death via vaporization in clinical settings.
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Affiliation(s)
- Donald A Fernandes
- Department of Chemistry & Biology, Ryerson University, Toronto, ON M5B 2K3, Canada; Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between Ryerson University and St. Michael's Hospital, Toronto, ON M5B 1T8, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, M5B 1T8, Canada.
| | - Dennis D Fernandes
- Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Aimen Malik
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Gregory-Neal W Gomes
- Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Sila Appak-Baskoy
- Department of Chemistry & Biology, Ryerson University, Toronto, ON M5B 2K3, Canada; Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between Ryerson University and St. Michael's Hospital, Toronto, ON M5B 1T8, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, M5B 1T8, Canada
| | - Elizabeth Berndl
- Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between Ryerson University and St. Michael's Hospital, Toronto, ON M5B 1T8, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, M5B 1T8, Canada; Department of Physics, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Claudiu C Gradinaru
- Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada.
| | - Michael C Kolios
- Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between Ryerson University and St. Michael's Hospital, Toronto, ON M5B 1T8, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, M5B 1T8, Canada; Department of Physics, Ryerson University, Toronto, ON M5B 2K3, Canada.
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Ligand modulation of the conformational dynamics of the A 2A adenosine receptor revealed by single-molecule fluorescence. Sci Rep 2021; 11:5910. [PMID: 33723285 PMCID: PMC7960716 DOI: 10.1038/s41598-021-84069-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/11/2021] [Indexed: 02/07/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest class of transmembrane proteins, making them an important target for therapeutics. Activation of these receptors is modulated by orthosteric ligands, which stabilize one or several states within a complex conformational ensemble. The intra- and inter-state dynamics, however, is not well documented. Here, we used single-molecule fluorescence to measure ligand-modulated conformational dynamics of the adenosine A2A receptor (A2AR) on nanosecond to millisecond timescales. Experiments were performed on detergent-purified A2R in either the ligand-free (apo) state, or when bound to an inverse, partial or full agonist ligand. Single-molecule Förster resonance energy transfer (smFRET) was performed on detergent-solubilized A2AR to resolve active and inactive states via the separation between transmembrane (TM) helices 4 and 6. The ligand-dependent changes of the smFRET distributions are consistent with conformational selection and with inter-state exchange lifetimes ≥ 3 ms. Local conformational dynamics around residue 2296.31 on TM6 was measured using fluorescence correlation spectroscopy (FCS), which captures dynamic quenching due to photoinduced electron transfer (PET) between a covalently-attached dye and proximal aromatic residues. Global analysis of PET-FCS data revealed fast (150-350 ns), intermediate (50-60 μs) and slow (200-300 μs) conformational dynamics in A2AR, with lifetimes and amplitudes modulated by ligands and a G-protein mimetic (mini-Gs). Most notably, the agonist binding and the coupling to mini-Gs accelerates and increases the relative contribution of the sub-microsecond phase. Molecular dynamics simulations identified three tyrosine residues (Y112, Y2887.53, and Y2907.55) as being responsible for the dynamic quenching observed by PET-FCS and revealed associated helical motions around residue 2296.31 on TM6. This study provides a quantitative description of conformational dynamics in A2AR and supports the idea that ligands bias not only GPCR conformations but also the dynamics within and between distinct conformational states of the receptor.
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Fernandes DD, Bamrah J, Kailasam S, Gomes GNW, Li Y, Wieden HJ, Gradinaru CC. Characterization of Fluorescein Arsenical Hairpin (FlAsH) as a Probe for Single-Molecule Fluorescence Spectroscopy. Sci Rep 2017; 7:13063. [PMID: 29026195 PMCID: PMC5638890 DOI: 10.1038/s41598-017-13427-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 09/21/2017] [Indexed: 01/27/2023] Open
Abstract
In recent years, new labelling strategies have been developed that involve the genetic insertion of small amino-acid sequences for specific attachment of small organic fluorophores. Here, we focus on the tetracysteine FCM motif (FLNCCPGCCMEP), which binds to fluorescein arsenical hairpin (FlAsH), and the ybbR motif (TVLDSLEFIASKLA) which binds fluorophores conjugated to Coenzyme A (CoA) via a phosphoryl transfer reaction. We designed a peptide containing both motifs for orthogonal labelling with FlAsH and Alexa647 (AF647). Molecular dynamics simulations showed that both motifs remain solvent-accessible for labelling reactions. Fluorescence spectra, correlation spectroscopy and anisotropy decay were used to characterize labelling and to obtain photophysical parameters of free and peptide-bound FlAsH. The data demonstrates that FlAsH is a viable probe for single-molecule studies. Single-molecule imaging confirmed dual labeling of the peptide with FlAsH and AF647. Multiparameter single-molecule Förster Resonance Energy Transfer (smFRET) measurements were performed on freely diffusing peptides in solution. The smFRET histogram showed different peaks corresponding to different backbone and dye orientations, in agreement with the molecular dynamics simulations. The tandem of fluorophores and the labelling strategy described here are a promising alternative to bulky fusion fluorescent proteins for smFRET and single-molecule tracking studies of membrane proteins.
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Affiliation(s)
- Dennis D Fernandes
- Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7, Canada.
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, L5L 1C6, Canada.
| | - Jasbir Bamrah
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, L5L 1C6, Canada
| | - Senthilkumar Kailasam
- Alberta RNA Research & Training Institute, Department of Chemistry & Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Gregory-Neal W Gomes
- Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7, Canada
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, L5L 1C6, Canada
| | - Yuchong Li
- Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7, Canada
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, L5L 1C6, Canada
| | - Hans-Joachim Wieden
- Alberta RNA Research & Training Institute, Department of Chemistry & Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Claudiu C Gradinaru
- Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7, Canada.
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, L5L 1C6, Canada.
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Zhang Z, Yomo D, Gradinaru C. Choosing the right fluorophore for single-molecule fluorescence studies in a lipid environment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1242-1253. [PMID: 28392350 DOI: 10.1016/j.bbamem.2017.04.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/14/2017] [Accepted: 04/05/2017] [Indexed: 10/19/2022]
Abstract
Nonspecific interactions between lipids and fluorophores can alter the outcomes of single-molecule spectroscopy of membrane proteins in live cells, liposomes or lipid nanodiscs and of cytosolic proteins encapsulated in liposomes or tethered to supported lipid bilayers. To gain insight into these effects, we examined interactions between 9 dyes that are commonly used as labels for single-molecule fluorescence (SMF) and 6 standard lipids including cationic, zwitterionic and anionic types. The diffusion coefficients of dyes in the absence and presence of set amounts of lipid vesicles were measured by fluorescence correlation spectroscopy (FCS). The partition coefficients and the free energies of partitioning for different fluorophore-lipid pairs were obtained by global fitting of the titration FCS curves. Lipids with different charges, head groups and degrees of chain saturation were investigated, and interactions with dyes are discussed in terms of hydrophobic, electrostatic and steric contributions. Fluorescence imaging of individual fluorophores adsorbed on supported lipid bilayers provides visualization and additional quantification of the strength of dye-lipid interaction in the context of single-molecule measurements. By dissecting fluorophore-lipid interactions, our study provides new insights into setting up single-molecule fluorescence spectroscopy experiments with minimal interference from interactions between fluorescent labels and lipids in the environment.
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Affiliation(s)
- Zhenfu Zhang
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Dan Yomo
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Claudiu Gradinaru
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada.
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Fernandes DA, Fernandes DD, Li Y, Wang Y, Zhang Z, Rousseau D, Gradinaru CC, Kolios MC. Synthesis of Stable Multifunctional Perfluorocarbon Nanoemulsions for Cancer Therapy and Imaging. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10870-10880. [PMID: 27564412 DOI: 10.1021/acs.langmuir.6b01867] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Nanotechnology provides a promising platform for drug-delivery in medicine. Nanostructured materials can be designed with desired superparamagnetic or fluorescent properties in conjunction with biochemically functionalized moieties (i.e., antibodies, peptides, and small molecules) to actively bind to target sites. These multifunctional properties make them suitable agents for multimodal imaging, diagnosis, and therapy. Perfluorohexane nanoemulsions (PFH-NEs) are novel drug-delivery vehicles and contrast agents for ultrasound and photoacoustic imaging of cancer in vivo, offering higher spatial resolution and deeper penetration of tissue when compared to conventional optical techniques. Compared to other theranostic agents, our PFH-NEs are one of the smallest of their kind (<100 nm), exhibit minimal aggregation, long-term stability at physiological conditions, and provide a noninvasive cancer imaging and therapy alternative for patients. Here, we show, using high-resolution imaging and correlative techniques, that our PFH-NEs, when in tandem with silica-coated gold nanoparticles (scAuNPs), can be used as a drug-loaded therapeutic via endocytosis and as a multimodal imaging agent for photoacoustic, ultrasound, and fluorescence imaging of tumor growth.
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Affiliation(s)
| | - Dennis D Fernandes
- Department of Physics, University of Toronto , 60 St George Streeet, Toronto, Ontario M5S 1A7, Canada
- Department of Chemical and Physical Sciences, University of Toronto Mississauga , 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada
| | - Yuchong Li
- Department of Physics, University of Toronto , 60 St George Streeet, Toronto, Ontario M5S 1A7, Canada
- Department of Chemical and Physical Sciences, University of Toronto Mississauga , 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada
| | | | - Zhenfu Zhang
- Department of Physics, University of Toronto , 60 St George Streeet, Toronto, Ontario M5S 1A7, Canada
- Department of Chemical and Physical Sciences, University of Toronto Mississauga , 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada
| | | | - Claudiu C Gradinaru
- Department of Physics, University of Toronto , 60 St George Streeet, Toronto, Ontario M5S 1A7, Canada
- Department of Chemical and Physical Sciences, University of Toronto Mississauga , 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada
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Banks DS, Tressler C, Peters RD, Höfling F, Fradin C. Characterizing anomalous diffusion in crowded polymer solutions and gels over five decades in time with variable-lengthscale fluorescence correlation spectroscopy. SOFT MATTER 2016; 12:4190-4203. [PMID: 27050290 DOI: 10.1039/c5sm01213a] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The diffusion of macromolecules in cells and in complex fluids is often found to deviate from simple Fickian diffusion. One explanation offered for this behavior is that molecular crowding renders diffusion anomalous, where the mean-squared displacement of the particles scales as 〈r(2)〉∝t(α) with α < 1. Unfortunately, methods such as fluorescence correlation spectroscopy (FCS) or fluorescence recovery after photobleaching (FRAP) probe diffusion only over a narrow range of lengthscales and cannot directly test the dependence of the mean-squared displacement (MSD) on time. Here we show that variable-lengthscale FCS (VLS-FCS), where the volume of observation is varied over several orders of magnitude, combined with a numerical inversion procedure of the correlation data, allows retrieving the MSD for up to five decades in time, bridging the gap between diffusion experiments performed at different lengthscales. In addition, we show that VLS-FCS provides a way to assess whether the propagator associated with the diffusion is Gaussian or non-Gaussian. We used VLS-FCS to investigate two systems where anomalous diffusion had been previously reported. In the case of dense cross-linked agarose gels, the measured MSD confirmed that the diffusion of small beads was anomalous at short lengthscales, with a cross-over to simple diffusion around ≈1 μm, consistent with a caged diffusion process. On the other hand, for solutions crowded with marginally entangled dextran molecules, we uncovered an apparent discrepancy between the MSD, found to be linear, and the propagators at short lengthscales, found to be non-Gaussian. These contradicting features call to mind the "anomalous, yet Brownian" diffusion observed in several biological systems, and the recently proposed "diffusing diffusivity" model.
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Affiliation(s)
- Daniel S Banks
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W, Hamilton, ON L8S 4M1, Canada.
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Liu B, Chia D, Csizmok V, Farber P, Forman-Kay JD, Gradinaru CC. The effect of intrachain electrostatic repulsion on conformational disorder and dynamics of the Sic1 protein. J Phys Chem B 2014; 118:4088-97. [PMID: 24673507 DOI: 10.1021/jp500776v] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The yeast cyclin-dependent kinase inhibitor Sic1 is a disordered protein that, upon multisite phosphorylation, forms a dynamic complex with the Cdc4 subunit of an SCF ubiquitin ligase. To understand the multisite phosphorylation dependence of the Sic1:Cdc4 interaction, which ultimately leads to a sharp cell cycle transition, the conformational properties of the disordered Sic1 N-terminal targeting region were studied using single-molecule fluorescence spectroscopy. Multiple conformational populations with different sensitivities to charge screening were identified by performing experiments in nondenaturing salts and ionic denaturants. Both the end-to-end distance and the hydrodynamic radius decrease monotonically with increasing the salt concentration, and a rollover of the chain dimensions in high denaturant conditions is observed. The data were fit to the polyelectrolyte binding-screening model, yielding parameters such as the excluded volume of the uncharged chain and the binding constant to denaturant. An overall scaling factor of ∼1.2 was needed for fitting the data, which implies that Sic1 cannot be approximated by a random Gaussian chain. Fluorescence correlation spectroscopy reveals Sic1 structure fluctuations occurring on both fast (10-100 ns) and slow (∼10 ms) time scales, with the fast phase absent in low salt solutions. The results of this study provide direct evidence that long-range intrachain electrostatic repulsions are a significant factor for the conformational landscape of Sic1, and support the role of electrostatics in determining the overall shape and hydrodynamic properties of intrinsically disordered proteins.
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Affiliation(s)
- Baoxu Liu
- Department of Chemical and Physical Sciences, University of Toronto Mississauga , Mississauga, Ontario L5L 1C6, Canada
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Chattoraj S, Mandal AK, Bhattacharyya K. Effect of ethanol-water mixture on the structure and dynamics of lysozyme: A fluorescence correlation spectroscopy study. J Chem Phys 2014; 140:115105. [DOI: 10.1063/1.4868642] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Crowding in Polymer–Nanoparticle Mixtures. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 307:27-71. [DOI: 10.1016/b978-0-12-800046-5.00003-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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Basak S, Chattopadhyay K. Studies of protein folding and dynamics using single molecule fluorescence spectroscopy. Phys Chem Chem Phys 2014; 16:11139-49. [DOI: 10.1039/c3cp55219e] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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