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Rotz MW, Holbrook RJ, MacRenaris KW, Meade TJ. A Markedly Improved Synthetic Approach for the Preparation of Multifunctional Au-DNA Nanoparticle Conjugates Modified with Optical and MR Imaging Probes. Bioconjug Chem 2018; 29:3544-3549. [PMID: 30193061 DOI: 10.1021/acs.bioconjchem.8b00504] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe a new, and vastly superior approach for labeling spherical nucleic acid conjugates (SNAs) with diagnostic probes. SNAs have been shown to provide the unique ability to traverse the cell membrane and deliver surface conjugated DNA into cells while preserving the DNA from nuclease degradation. Our previous work on preparing diagnostically labeled SNAs was labor intensive, relatively low yielding, and costly. Here, we describe a straightforward and facile preparation for labeling SNAs with optical and MR imaging probes with significantly improved physical properties. The synthesis of Gd(III) labeled DNA Au nanoparticle conjugates is achieved by sequential conjugation of 3'-thiol-modified oligonucleotides and cofunctionalization of the particle surface with the subsequent addition of 1,2 diothiolate modified chelates of Gd(III) (abbreviated: DNA-GdIII@AuNP). This new generation of SNA conjugates has a 2-fold increase of DNA labeling and a 1.4-fold increase in Gd(III) loading compared to published constructs. Furthermore, the relaxivity ( r1) is observed to increase 4.5-fold compared to the molecular dithiolane-Gd(III) complex, and 1.4-fold increase relative to previous particle constructs where the Gd(III) complexes were conjugated to the oligonucleotides rather than directly to the Au particle. Importantly, this simplified approach (2 steps) exploits the advantages of previous Gd(III) labeled SNA platforms; however, this new approach is scalable and eliminates modification of DNA for attaching the contrast agent, and the particles exhibit improved cell labeling.
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Lilley LM, Du K, Krzyaniak MD, Parigi G, Luchinat C, Harris TD, Meade TJ. Effect of Magnetic Coupling on Water Proton Relaxivity in a Series of Transition Metal Gd III Complexes. Inorg Chem 2018; 57:5810-5819. [PMID: 29714477 DOI: 10.1021/acs.inorgchem.8b00120] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A fundamental challenge in the design of bioresponsive (or bioactivated) GdIII-based magnetic resonance (MR) imaging probes is the considerable background signal present in the "preactivated" state that arises from outer-sphere relaxation processes. When sufficient concentrations of a bioresponsive agent are present (i.e., a detectable signal in the image), the inner- and outer-sphere contributions to r1 may be misinterpreted to conclude that the agent has been activated, when it has not. Of the several parameters that determine the observed MR signal of an agent, only the electron relaxation time ( T1e) impacts both the inner- and outer-sphere relaxation. Therefore, strategies to minimize this background signal must be developed to create a near zero-background (or truly "off" state) of the agent. Here, we demonstrate that intramolecular magnetic exchange coupling when GdIII is coupled to a paramagnetic transition metal provides a means to overcome the contribution of second- and outer-sphere contributions to the observed relaxivity. We have prepared a series of complexes with the general formula LMLn(μ-O2CCH3)(O2CCH3)2 (M = Co, Cu, Zn). Solid-state magnetic susceptibility measurements reveal significant magnetic coupling between GdIII and the transition metal ion. Nuclear magnetic relaxation dispersion (NMRD) analysis confirms that the observed differences in relaxivity are associated with the modulation of T1e at GdIII. These results clearly demonstrate that magnetic exchange coupling between GdIII and a transition metal ion can provide a significant decrease in T1e (and therefore the relaxivity of GdIII). This design strategy is being exploited to prepare new generations of preclinical bioresponsive MR imaging probes with near zero-background.
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Preslar AT, Lilley LM, Sato K, Zhang S, Chia ZK, Stupp SI, Meade TJ. Calcium-Induced Morphological Transitions in Peptide Amphiphiles Detected by 19F-Magnetic Resonance Imaging. ACS APPLIED MATERIALS & INTERFACES 2017; 9:39890-39894. [PMID: 28915004 PMCID: PMC5735829 DOI: 10.1021/acsami.7b07828] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Misregulation of extracellular Ca2+ can indicate bone-related pathologies. New, noninvasive tools are required to image Ca2+ fluxes and fluorine magnetic resonance imaging (19F-MRI) is uniquely suited to this challenge. Here, we present three, highly fluorinated peptide amphiphiles that self-assemble into nanoribbons in buffered saline and demonstrate these nanostructures can be programmed to change 19F-NMR signal intensity as a function of Ca2+ concentration. We determined these nanostructures show significant reduction in 19F-NMR signal as nanoribbon width increases in response to Ca2+, corresponding to 19F-MR image intensity reduction. Thus, these peptide amphiphiles can be used to quantitatively image biologically relevant Ca2+ concentrations.
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Verma KD, Massing JO, Kamper SG, Carney CE, MacRenaris KW, Basilion JP, Meade TJ. Synthesis and evaluation of MR probes for targeted-reporter imaging. Chem Sci 2017; 8:5764-5768. [PMID: 28989616 PMCID: PMC5621504 DOI: 10.1039/c7sc02217d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 06/10/2017] [Indexed: 12/30/2022] Open
Abstract
Visualizing disease heterogeneity remains a challenging task since most imaging agents are targeted to a single receptor. We describe the development of an MR platform able to report on multiple molecular events. Enzyme activation and enhanced cellular uptake of this modular probe make it suitable for subsequent targeted-reporter imaging applications.
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Hung AH, Lilley LM, Hu F, Harrison VSR, Meade TJ. Magnetic barcode imaging for contrast agents. Magn Reson Med 2017; 77:970-978. [PMID: 27062518 PMCID: PMC5055837 DOI: 10.1002/mrm.26175] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/27/2016] [Accepted: 01/28/2016] [Indexed: 11/11/2022]
Abstract
PURPOSE To demonstrate a new MR imaging approach that unambiguously identifies and quantitates contrast agents based on intrinsic agent properties such as r1 , r2 , r2*, and magnetic susceptibility. The approach is referred to as magnetic barcode imaging (MBI). METHODS Targeted and bioresponsive contrast agents were imaged in agarose phantoms to generate T1 , T2 , T2*, and quantitative susceptibility maps. The parameter maps were processed by a machine learning algorithm that is trained to recognize the contrast agents based on these parameters. The output is a quantitative map of contrast agent concentration, identity, and functional state. RESULTS MBI allowed the quantitative interpretation of intensities, removed confounding backgrounds, enabled contrast agent multiplexing, and unambiguously detected the activation and binding states of bioresponsive and targeted contrast agents. CONCLUSION MBI has the potential to overcome significant limitations in the interpretation, quantitation, and multiplexing of contrast enhancement by MR imaging probes. Magn Reson Med 77:970-978, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Rammohan N, Holbrook RJ, Rotz MW, MacRenaris KW, Preslar AT, Carney CE, Reichova V, Meade TJ. Gd(III)-Gold Nanoconjugates Provide Remarkable Cell Labeling for High Field Magnetic Resonance Imaging. Bioconjug Chem 2017; 28:153-160. [PMID: 27537821 PMCID: PMC5243168 DOI: 10.1021/acs.bioconjchem.6b00389] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In vivo cell tracking is vital for understanding migrating cell populations, particularly cancer and immune cells. Magnetic resonance (MR) imaging for long-term tracking of transplanted cells in live organisms requires cells to effectively internalize Gd(III) contrast agents (CAs). Clinical Gd(III)-based CAs require high dosing concentrations and extended incubation times for cellular internalization. To combat this, we have devised a series of Gd(III)-gold nanoconjugates (Gd@AuNPs) with varied chelate structure and nanoparticle-chelate linker length, with the goal of labeling and imaging breast cancer cells. These new Gd@AuNPs demonstrate significantly enhanced labeling compared to previous Gd(III)-gold-DNA nanoconstructs. Variations in Gd(III) loading, surface packing, and cell uptake were observed among four different Gd@AuNP formulations suggesting that linker length and surface charge play an important role in cell labeling. The best performing Gd@AuNPs afforded 23.6 ± 3.6 fmol of Gd(III) per cell at an incubation concentration of 27.5 μM-this efficiency of Gd(III) payload delivery (Gd(III)/cell normalized to dose) exceeds that of previous Gd(III)-Au conjugates and most other Gd(III)-nanoparticle formulations. Further, Gd@AuNPs were well-tolerated in vivo in terms of biodistribution and clearance, and supports future cell tracking applications in whole-animal models.
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Rammohan N, MacRenaris KW, Moore LK, Parigi G, Mastarone DJ, Manus LM, Lilley LM, Preslar AT, Waters EA, Filicko A, Luchinat C, Ho D, Meade TJ. Nanodiamond-Gadolinium(III) Aggregates for Tracking Cancer Growth In Vivo at High Field. NANO LETTERS 2016; 16:7551-7564. [PMID: 27960515 PMCID: PMC5482002 DOI: 10.1021/acs.nanolett.6b03378] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The ability to track labeled cancer cells in vivo would allow researchers to study their distribution, growth, and metastatic potential within the intact organism. Magnetic resonance (MR) imaging is invaluable for tracking cancer cells in vivo as it benefits from high spatial resolution and the absence of ionizing radiation. However, many MR contrast agents (CAs) required to label cells either do not significantly accumulate in cells or are not biologically compatible for translational studies. We have developed carbon-based nanodiamond-gadolinium(III) aggregates (NDG) for MR imaging that demonstrated remarkable properties for cell tracking in vivo. First, NDG had high relaxivity independent of field strength, a finding unprecedented for gadolinium(III) [Gd(III)]-nanoparticle conjugates. Second, NDG demonstrated a 300-fold increase in the cellular delivery of Gd(III) compared to that of clinical Gd(III) chelates without sacrificing biocompatibility. Further, we were able to monitor the tumor growth of NDG-labeled flank tumors by T1- and T2-weighted MR imaging for 26 days in vivo, longer than was reported for other MR CAs or nuclear agents. Finally, by utilizing quantitative maps of relaxation times, we were able to describe tumor morphology and heterogeneity (corroborated by histological analysis), which would not be possible with competing molecular imaging modalities.
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Vistain LF, Rotz MW, Rathore R, Preslar AT, Meade TJ. Targeted delivery of gold nanoparticle contrast agents for reporting gene detection by magnetic resonance imaging. Chem Commun (Camb) 2016; 52:160-3. [PMID: 26505558 DOI: 10.1039/c5cc06565h] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Detection of protein expression by MRI requires a high payload of Gd(III) per protein binding event. Presented here is a targeted AuDNA nanoparticle capable of delivering several hundred Gd(III) chelates to the HaloTag reporter protein. Incubating this particle with HaloTag-expressing cells produced a 9.4 contrast-to-noise ratio compared to non-expressing cells.
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Culver KSB, Shin YJ, Rotz MW, Meade TJ, Hersam MC, Odom TW. Shape-Dependent Relaxivity of Nanoparticle-Based T1 Magnetic Resonance Imaging Contrast Agents. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2016; 120:22103-22109. [PMID: 28008338 PMCID: PMC5172589 DOI: 10.1021/acs.jpcc.6b08362] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Gold nanostars functionalized with Gd(III) have shown significant promise as contrast agents for magnetic resonance imaging (MRI) because of their anisotropic, branched shape. However, the size and shape polydispersity of as-synthesized gold nanostars have precluded efforts to develop a rigorous relationship between the gold nanostar structure (e.g., number of branches) and relaxivity of surface-bound Gd(III). This paper describes the use of a centrifugal separation method that can produce structurally refined populations of gold nanostars and is compatible with Gd(III) functionalization. Combined transmission electron microscopy and relaxivity analyses revealed that the increased number of nanostar branches was correlated with enhanced relaxivity. By identifying the underlying relaxivity mechanisms for Gd(III)-functionalized gold nanostars, we can inform the design of high-performance MRI contrast agents.
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Preslar AT, Tantakitti F, Park K, Zhang S, Stupp SI, Meade TJ. (19)F Magnetic Resonance Imaging Signals from Peptide Amphiphile Nanostructures Are Strongly Affected by Their Shape. ACS NANO 2016; 10:7376-84. [PMID: 27425636 PMCID: PMC5036169 DOI: 10.1021/acsnano.6b00267] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Magnetic resonance imaging (MRI) is a noninvasive imaging modality that provides excellent spatial and temporal resolution. The most commonly used MR probes face significant challenges originating from the endogenous (1)H background signal of water. In contrast, fluorine MRI ((19)F MRI) allows quantitative probe imaging with zero background signal. Probes with high fluorine content are required for high sensitivity, suggesting nanoscale supramolecular assemblies containing (19)F probes offer a potentially useful strategy for optimum imaging as a result of improved payload. We report here on supramolecular nanostructures formed by fluorinated peptide amphiphiles containing either glutamic acid or lysine residues in their sequence. We identified molecules that form aggregates in water which transition from cylindrical to ribbon-like shape as pH increased from 4.5 to 8.0. Interestingly, we found that ribbon-like nanostructures had reduced magnetic resonance signal, whereas their cylindrical counterparts exhibited strong signals. We attribute this drastic difference to the greater mobility of fluorinated tails in the hydrophobic compartment of cylindrical nanostructures compared to lower mobility in ribbon-like assemblies. This discovery identifies a strategy to design supramolecular, self-assembling contrast agents for (19)F MRI that can spatially map physiologically relevant changes in pH using changes in morphology.
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Holbrook RJ, Rammohan N, Rotz MW, MacRenaris KW, Preslar AT, Meade TJ. Gd(III)-Dithiolane Gold Nanoparticles for T1-Weighted Magnetic Resonance Imaging of the Pancreas. NANO LETTERS 2016; 16:3202-9. [PMID: 27050622 PMCID: PMC5045863 DOI: 10.1021/acs.nanolett.6b00599] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Pancreatic adenocarcinoma has a 5 year survival of approximately 3% and median survival of 6 months and is among the most dismal of prognoses in all of medicine. This poor prognosis is largely due to delayed diagnosis where patients remain asymptomatic until advanced disease is present. Therefore, techniques to allow early detection of pancreatic adenocarcinoma are desperately needed. Imaging of pancreatic tissue is notoriously difficult, and the development of new imaging techniques would impact our understanding of organ physiology and pathology with applications in disease diagnosis, staging, and longitudinal response to therapy in vivo. Magnetic resonance imaging (MRI) provides numerous advantages for these types of investigations; however, it is unable to delineate the pancreas due to low inherent contrast within this tissue type. To overcome this limitation, we have prepared a new Gd(III) contrast agent that accumulates in the pancreas and provides significant contrast enhancement by MR imaging. We describe the synthesis and characterization of a new dithiolane-Gd(III) complex and a straightforward and scalable approach for conjugation to a gold nanoparticle. We present data that show the nanoconjugates exhibit very high per particle values of r1 relaxivity at both low and high magnetic field strengths due to the high Gd(III) payload. We provide evidence of pancreatic tissue labeling that includes MR images, post-mortem biodistribution analysis, and pancreatic tissue evaluation of particle localization. Significant contrast enhancement was observed allowing clear identification of the pancreas with contrast-to-noise ratios exceeding 35:1.
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MacRenaris KW, Ma Z, Krueger RL, Carney CE, Meade TJ. Cell-Permeable Esterase-Activated Ca(II)-Sensitive MRI Contrast Agent. Bioconjug Chem 2016; 27:465-73. [PMID: 26689452 DOI: 10.1021/acs.bioconjchem.5b00561] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Calcium [Ca(II)] is a fundamental transducer of electrical activity in the central nervous system (CNS). Influx of Ca(II) into the cytosol is responsible for action potential initiation and propagation, and initiates interneuronal communication via release of neurotransmitters and activation of gene expression. Despite the importance of Ca(II) in physiology, it remains a challenge to visualize Ca(II) flux in the central nervous system (CNS) in vivo. To address these challenges, we have developed a new generation, Ca(II)-activated MRI contrast agent that utilizes ethyl esters to increase cell labeling and prevent extracellular divalent Ca(II) binding. Following labeling, the ethyl esters can be cleaved, thus allowing the agent to bind Ca(II), increasing relaxivity and resulting in enhanced positive MR image contrast. The ability of this probe to discriminate between extra- and intracellular Ca(II) may allow for spatiotemporal in vivo imaging of Ca(II) flux during seizures or ischemia where large Ca(II) fluxes (1-10 μM) can result in cell death.
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Preslar AT, Parigi G, McClendon MT, Sefick SS, Moyer TJ, Haney CR, Waters EA, MacRenaris KW, Luchinat C, Stupp SI, Meade TJ. Correction to Gd(III)-Labeled Peptide Nanofibers for Reporting on Biomaterial Localization in Vivo. ACS NANO 2015; 9:11502. [PMID: 26517476 PMCID: PMC4660387 DOI: 10.1021/acsnano.5b06496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Indexed: 06/05/2023]
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Nicholls FJ, Rotz MW, Ghuman H, MacRenaris KW, Meade TJ, Modo M. DNA-gadolinium-gold nanoparticles for in vivo T1 MR imaging of transplanted human neural stem cells. Biomaterials 2015; 77:291-306. [PMID: 26615367 DOI: 10.1016/j.biomaterials.2015.11.021] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 10/21/2015] [Accepted: 11/10/2015] [Indexed: 01/18/2023]
Abstract
The unambiguous imaging of transplanted cells remains a major challenge to understand their biological function and therapeutic efficacy. In vivo imaging of implanted cells is reliant on tagging these to differentiate them from host tissue, such as the brain. We here characterize a gold nanoparticle conjugate that is functionalized with modified deoxythymidine oligonucleotides bearing Gd(III) chelates and a red fluorescent Cy3 moiety to visualize in vivo transplanted human neural stem cells. This DNA-Gd@Au nanoparticle (DNA-Gd@AuNP) exhibits an improved T1 relaxivity and excellent cell uptake. No significant effects of cell uptake have been found on essential cell functions. Although T1 relaxivity is attenuated within cells, it is sufficiently preserved to afford the in vivo detection of transplanted cells using an optimized voxel size. In vivo MR images were corroborated by a post-mortem histological verification of DNA-Gd@AuNPs in transplanted cells. With 70% of cells being correctly identified using the DNA-Gd-AuNPs indicates an overall reliable detection. Less than 1% of cells were false positive for DNA-Gd@AuNPs, but a significant number of 30% false negatives reveals a dramatic underestimation of transplanted cells using this approach. DNA-Gd@AuNPs therefore offer new opportunities to visualize transplanted cells unequivocally using T1 contrast and use cellular MRI as a tool to derive biologically relevant information that allows us to understand how the survival and location of implanted cells determines therapeutic efficacy.
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Heffern MC, Reichova V, Coomes JL, Harney AS, Bajema EA, Meade TJ. Tuning cobalt(III) Schiff base complexes as activated protein inhibitors. Inorg Chem 2015; 54:9066-74. [PMID: 26331337 PMCID: PMC4638226 DOI: 10.1021/acs.inorgchem.5b01415] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cobalt(III) Schiff base complexes ([Co(acacen)(L)2](+), where L = NH3) inhibit histidine-containing proteins through dissociative exchange of the labile axial ligands (L). This work investigates axial ligand exchange dynamics of [Co(acacen)(L)2](+) complexes toward the development of protein inhibitors that are activated by external triggers such as light irradiation. We sought to investigate ligand exchange dynamics to design a Co(III) complex that is substitutionally inert under normal physiological conditions for selective activation. Fluorescent imidazoles (C3Im) were prepared as axial ligands in [Co(acacen)(L)2](+) to produce complexes (CoC3Im) that could report on ligand exchange and, thus, complex stability. These fluorescent imidazole reporters guided the design of a new dinuclear Co(III) Schiff base complex containing bridging diimidazole ligands, which exhibits enhanced stability to ligand exchange with competing imidazoles and to hydrolysis within a biologically relevant pH range. These studies inform the design of biocompatible Co(III) Schiff base complexes that can be selectively activated for protein inhibition with spatial and temporal specificity.
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41
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Vistain LF, Yamamoto N, Rathore R, Cha P, Meade TJ. Targeted Inhibition of Snail Activity in Breast Cancer Cells by Using a Co(III) -Ebox Conjugate. Chembiochem 2015; 16:2065-72. [PMID: 26305708 DOI: 10.1002/cbic.201500289] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Indexed: 12/29/2022]
Abstract
The transition from a non-invasive to an invasive phenotype is an essential step in tumor metastasis. The Snail family of transcription factors (TFs) is known to play a significant role in this transition. These TFs are zinc fingers that bind to the CAGGTG Ebox consensus sequence. Co(III) -Ebox is a cobalt(III) complex attached to an Ebox oligonucleotide that confers specificity towards Snail TFs. Co(III) -Ebox has been shown to inhibit Snail-mediated embryonic neural crest development in Xenopus laevis, but its efficacy in inhibiting Snail-induced cancer cell invasiveness has not been explored. Here, we describe the efficacy of Co(III) -Ebox in inhibiting the invasive aspects of heregulin-β1(HRG)-treated breast cancer cells. Co(III) -Ebox was found to inhibit the capacity of Snail to repress target genes after HRG induction. Snail inhibition by Co(III) -Ebox reduced the invasive propensity of cells in 2D and 3D, thereby demonstrating promise in inhibiting metastasis.
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Carney CE, MacRenaris KW, Meade TJ. Water-soluble lipophilic MR contrast agents for cell membrane labeling. J Biol Inorg Chem 2015. [PMID: 26215869 DOI: 10.1007/s00775-015-1280-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Long-term cell tracking using MR imaging necessitates the development of contrast agents that both label and are retained by cells. One promising strategy for long-term cell labeling is the development of lipophilic Gd(III)-based contrast agents that anchor into the cell membrane. We have previously reported the efficacy of monomeric and multimeric lipophilic agents and showed that the monomeric agents have improved labeling and contrast enhancement of cell populations. Here, we report on the synthesis, characterization, and in vitro testing of a series of monomeric lipophilic contrast agents with varied alkyl chain compositions. We show that these agents disperse in water, localize to the cell membrane, and label HeLa and MCF7 cells effectively. Additionally, these agents have up to tenfold improved retention in cells compared to clinically available ProHance(®).
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Banerjee SR, Ngen EJ, Rotz MW, Kakkad S, Lisok A, Pracitto R, Pullambhatla M, Chen Z, Shah T, Artemov D, Meade TJ, Bhujwalla ZM, Pomper MG. Synthesis and Evaluation of GdIII-Based Magnetic Resonance Contrast Agents for Molecular Imaging of Prostate-Specific Membrane Antigen. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201503417] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Banerjee SR, Ngen EJ, Rotz MW, Kakkad S, Lisok A, Pracitto R, Pullambhatla M, Chen Z, Shah T, Artemov D, Meade TJ, Bhujwalla ZM, Pomper MG. Synthesis and Evaluation of Gd(III) -Based Magnetic Resonance Contrast Agents for Molecular Imaging of Prostate-Specific Membrane Antigen. Angew Chem Int Ed Engl 2015. [PMID: 26212031 DOI: 10.1002/anie.201503417] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Magnetic resonance (MR) imaging is advantageous because it concurrently provides anatomic, functional, and molecular information. MR molecular imaging can combine the high spatial resolution of this established clinical modality with molecular profiling in vivo. However, as a result of the intrinsically low sensitivity of MR imaging, high local concentrations of biological targets are required to generate discernable MR contrast. We hypothesize that the prostate-specific membrane antigen (PSMA), an attractive target for imaging and therapy of prostate cancer, could serve as a suitable biomarker for MR-based molecular imaging. We have synthesized three new high-affinity, low-molecular-weight Gd(III) -based PSMA-targeted contrast agents containing one to three Gd(III) chelates per molecule. We evaluated the relaxometric properties of these agents in solution, in prostate cancer cells, and in an in vivo experimental model to demonstrate the feasibility of PSMA-based MR molecular imaging.
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Harrison VSR, Carney CE, MacRenaris KW, Waters EA, Meade TJ. Multimeric Near IR-MR Contrast Agent for Multimodal In Vivo Imaging. J Am Chem Soc 2015; 137:9108-16. [PMID: 26083313 PMCID: PMC4512902 DOI: 10.1021/jacs.5b04509] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Multiple imaging modalities are often required for in vivo imaging applications that require both high probe sensitivity and excellent spatial and temporal resolution. In particular, MR and optical imaging are an attractive combination that can be used to determine both molecular and anatomical information. Herein, we describe the synthesis and in vivo testing of two multimeric NIR-MR contrast agents that contain three Gd(III) chelates and an IR-783 dye moiety. One agent contains a PEG linker and the other a short alkyl linker. These agents label cells with extraordinary efficacy and can be detected in vivo using both imaging modalities. Biodistribution of the PEGylated agent shows observable fluorescence in xenograft MCF7 tumors and renal clearance by MR imaging.
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Harrison VSR, Carney CE, Macrenaris KW, Meade TJ. A multimeric MR-optical contrast agent for multimodal imaging. Chem Commun (Camb) 2015; 50:11469-71. [PMID: 25137290 DOI: 10.1039/c4cc05651e] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We describe the design, synthesis and in vitro evaluation of a multimodal and multimeric contrast agent. The agent consists of three macrocyclic Gd(III) chelates conjugated to a fluorophore and possesses high relaxivity, water solubility, and is nontoxic. The modular synthesis is amenable for the incorporation of a variety of fluorophores to generate molecular constructs for a number of applications.
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Carney CE, Lenov IL, Baker CJ, MacRenaris KW, Eckermann AL, Sligar SG, Meade TJ. Nanodiscs as a Modular Platform for Multimodal MR-Optical Imaging. Bioconjug Chem 2015; 26:899-905. [PMID: 25830565 DOI: 10.1021/acs.bioconjchem.5b00107] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Nanodiscs are monodisperse, self-assembled discoidal particles that consist of a lipid bilayer encircled by membrane scaffold proteins (MSP). Nanodiscs have been used to solubilize membrane proteins for structural and functional studies and deliver therapeutic phospholipids. Herein, we report on tetramethylrhodamine (TMR) tagged nanodiscs that solubilize lipophilic MR contrast agents for generation of multimodal nanoparticles for cellular imaging. We incorporate both multimeric and monomeric Gd(III)-based contrast agents into nanodiscs and show that particles containing the monomeric agent (ND2) label cells with high efficiency and generate significant image contrast at 7 T compared to nanodiscs containing the multimeric agent (ND1) and Prohance, a clinically approved contrast agent.
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Rotz MW, Culver KSB, Parigi G, MacRenaris KW, Luchinat C, Odom TW, Meade TJ. High relaxivity Gd(III)-DNA gold nanostars: investigation of shape effects on proton relaxation. ACS NANO 2015; 9:3385-96. [PMID: 25723190 PMCID: PMC4489565 DOI: 10.1021/nn5070953] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Gadolinium(III) nanoconjugate contrast agents (CAs) have distinct advantages over their small-molecule counterparts in magnetic resonance imaging. In addition to increased Gd(III) payload, a significant improvement in proton relaxation efficiency, or relaxivity (r1), is often observed. In this work, we describe the synthesis and characterization of a nanoconjugate CA created by covalent attachment of Gd(III) to thiolated DNA (Gd(III)-DNA), followed by surface conjugation onto gold nanostars (DNA-Gd@stars). These conjugates exhibit remarkable r1 with values up to 98 mM(-1) s(-1). Additionally, DNA-Gd@stars show efficient Gd(III) delivery and biocompatibility in vitro and generate significant contrast enhancement when imaged at 7 T. Using nuclear magnetic relaxation dispersion analysis, we attribute the high performance of the DNA-Gd@stars to an increased contribution of second-sphere relaxivity compared to that of spherical CA equivalents (DNA-Gd@spheres). Importantly, the surface of the gold nanostar contains Gd(III)-DNA in regions of positive, negative, and neutral curvature. We hypothesize that the proton relaxation enhancement observed results from the presence of a unique hydrophilic environment produced by Gd(III)-DNA in these regions, which allows second-sphere water molecules to remain adjacent to Gd(III) ions for up to 10 times longer than diffusion. These results establish that particle shape and second-sphere relaxivity are important considerations in the design of Gd(III) nanoconjugate CAs.
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Holbrook RJ, Weinberg DJ, Peterson MD, Weiss EA, Meade TJ. Light-activated protein inhibition through photoinduced electron transfer of a ruthenium(II)-cobalt(III) bimetallic complex. J Am Chem Soc 2015; 137:3379-85. [PMID: 25671465 DOI: 10.1021/jacs.5b00342] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We describe a mechanism of light activation that initiates protein inhibitory action of a biologically inert Co(III) Schiff base (Co(III)-sb) complex. Photoinduced electron transfer (PET) occurs from a Ru(II) bipyridal complex to a covalently attached Co(III) complex and is gated by conformational changes that occur in tens of nanoseconds. Reduction of the Co(III)-sb by PET initiates displacement of the inert axial imidazole ligands, promoting coordination to active site histidines of α-thrombin. Upon exposure to 455 nm light, the rate of ligand exchange with 4-methylimidazole, a histidine mimic, increases by approximately 5-fold, as observed by NMR spectroscopy. Similarly, the rate of α-thrombin inhibition increases over 5-fold upon irradiation. These results convey a strategy for light activation of inorganic therapeutic agents through PET utilizing redox-active metal centers.
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Khan MM, Michel SL, Heffern MC, Meade TJ, Hom K. Understanding the Transcriptional and Translational Regulatory Roles of Non-Classical Neural Zinc Finger Proteins Involved in the Development of the Nervous System. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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