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Ding S, Cargill AA, Das SR, Medintz IL, Claussen JC. Biosensing with Förster Resonance Energy Transfer Coupling between Fluorophores and Nanocarbon Allotropes. SENSORS 2015; 15:14766-87. [PMID: 26110411 PMCID: PMC4507682 DOI: 10.3390/s150614766] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 06/01/2015] [Accepted: 06/05/2015] [Indexed: 01/10/2023]
Abstract
Nanocarbon allotropes (NCAs), including zero-dimensional carbon dots (CDs), one-dimensional carbon nanotubes (CNTs) and two-dimensional graphene, exhibit exceptional material properties, such as unique electrical/thermal conductivity, biocompatibility and high quenching efficiency, that make them well suited for both electrical/electrochemical and optical sensors/biosensors alike. In particular, these material properties have been exploited to significantly enhance the transduction of biorecognition events in fluorescence-based biosensing involving Förster resonant energy transfer (FRET). This review analyzes current advances in sensors and biosensors that utilize graphene, CNTs or CDs as the platform in optical sensors and biosensors. Widely utilized synthesis/fabrication techniques, intrinsic material properties and current research examples of such nanocarbon, FRET-based sensors/biosensors are illustrated. The future outlook and challenges for the research field are also detailed.
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Ding S, Cargill AA, Medintz IL, Claussen JC. Increasing the activity of immobilized enzymes with nanoparticle conjugation. Curr Opin Biotechnol 2015; 34:242-50. [PMID: 25957941 DOI: 10.1016/j.copbio.2015.04.005] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 04/03/2015] [Accepted: 04/07/2015] [Indexed: 12/16/2022]
Abstract
The efficiency and selectivity of enzymatic catalysis is useful to a plethora of industrial and manufacturing processes. Many of these processes require the immobilization of enzymes onto surfaces, which has traditionally reduced enzyme activity. However, recent research has shown that the integration of nanoparticles into enzyme carrier schemes has maintained or even enhanced immobilized enzyme performance. The nanoparticle size and surface chemistry as well as the orientation and density of immobilized enzymes all contribute to the enhanced performance of enzyme-nanoparticle conjugates. These improvements are noted in specific nanoparticles including those comprising carbon (e.g., graphene and carbon nanotubes), metal/metal oxides and polymeric nanomaterials, as well as semiconductor nanocrystals or quantum dots.
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Field LD, Delehanty JB, Chen Y, Medintz IL. Peptides for specifically targeting nanoparticles to cellular organelles: quo vadis? Acc Chem Res 2015; 48:1380-90. [PMID: 25853734 DOI: 10.1021/ar500449v] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The interfacing of nanomaterials and especially nanoparticles within all aspects of biological research continues to grow at a nearly unabated pace with projected applications focusing on powerful new tools for cellular labeling, imaging, and sensing, theranostic materials, and drug delivery. At the most fundamental level, many of these nanoparticles are meant to target not only very specific cell-types, regardless of whether they are in a culture, tissue, an animal model, or ultimately a patient, but also in many cases a specific subcellular organelle. During this process, these materials will undergo a complex journey that must first find the target cell of interest, then be taken up by those cells across the extracellular membrane, and ultimately localize to a desired subcellular organelle, which may include the nucleus, plasma membrane, endolysosomal system, mitochondria, cytosol, or endoplasmic reticulum. To accomplish these complex tasks in the correct sequence, researchers are increasingly interested in selecting for and exploiting targeting peptides that can impart the requisite capabilities to a given nanoparticle construct. There are also a number of related criteria that need careful consideration for this undertaking centering on the nature and properties of the peptide vector itself, the peptide-nanoparticle conjugate characteristics, and the target cell. Here, we highlight some important issues and key research areas related to this burgeoning field. We begin by providing a brief overview of some criteria for optimal attachment of peptides to nanoparticles, the predominant methods by which nanoparticles enter cells, and some of the peptide sequences that have been utilized to facilitate nanoparticle delivery to cells focusing on those that engender the initial targeting and uptake. Because almost all materials delivered to cells by peptides utilize the endosomal system of vesicular transport and in many cases remain sequestered within the vesicles, we critically evaluate the issue of endosomal escape in the context of some recently reported successes in this regard. Following from this, peptides that have been reported to deliver nanoparticles to specific subcellular compartments are examined with a focus on what they delivered and the putative mechanisms by which they were able to accomplish this. The last section focuses on two areas that are critical to realizing this overall approach in the long term. The first is how to select for peptidyl sequences capable of improved or more specific cellular or subcellular targeting based upon principles commonly associated with drug discovery. The second looks at what has been done to create modular peptides that incorporate multiple desirable functionalities within a single, contiguous sequence. This provides a viable alternative to either the almost insurmountable challenge of finding one sequence capable of all functions or, alternatively, attaching different peptides with different functionalities to the same nanoparticle in different ratios when trying to orchestrate their net effects. Finally, we conclude with a brief perspective on the future evolution and broader impact of this growing area of bionanoscience.
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129
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Samanta A, Walper SA, Susumu K, Dwyer CL, Medintz IL. An enzymatically-sensitized sequential and concentric energy transfer relay self-assembled around semiconductor quantum dots. NANOSCALE 2015; 7:7603-7614. [PMID: 25804284 DOI: 10.1039/c5nr00828j] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The ability to control light energy within de novo nanoscale structures and devices will greatly benefit their continuing development and ultimate application. Ideally, this control should extend from generating the light itself to its spatial propagation within the device along with providing defined emission wavelength(s), all in a stand-alone modality. Here we design and characterize macromolecular nanoassemblies consisting of semiconductor quantum dots (QDs), several differentially dye-labeled peptides and the enzyme luciferase which cumulatively demonstrate many of these capabilities by engaging in multiple-sequential energy transfer steps. To create these structures, recombinantly-expressed luciferase and the dye-labeled peptides were appended with a terminal polyhistidine sequence allowing for controlled ratiometric self-assembly around the QDs via metal-affinity coordination. The QDs serve to provide multiple roles in these structures including as central assembly platforms or nanoscaffolds along with acting as a potent energy harvesting and transfer relay. The devices are activated by addition of coelenterazine H substrate which is oxidized by luciferase producing light energy which sensitizes the central 625 nm emitting QD acceptor by bioluminescence resonance energy transfer (BRET). The sensitized QD, in turn, acts as a relay and transfers the energy to a first peptide-labeled Alexa Fluor 647 acceptor dye displayed on its surface. This dye then transfers energy to a second red-shifted peptide-labeled dye acceptor on the QD surface through a second concentric Förster resonance energy transfer (FRET) process. Alexa Fluor 700 and Cy5.5 are both tested in the role of this terminal FRET acceptor. Photophysical analysis of spectral profiles from the resulting sequential BRET-FRET-FRET processes allow us to estimate the efficiency of each of the transfer steps. Importantly, the efficiency of each step within this energy transfer cascade can be controlled to some extent by the number of enzymes/peptides displayed on the QD. Further optimization of the energy transfer process(es) along with potential applications of such devices are finally discussed.
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130
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Walper SA, Turner KB, Medintz IL. Enzymatic bioconjugation of nanoparticles: developing specificity and control. Curr Opin Biotechnol 2015; 34:232-41. [PMID: 25955793 DOI: 10.1016/j.copbio.2015.04.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 03/30/2015] [Accepted: 04/01/2015] [Indexed: 12/31/2022]
Abstract
Nanoparticles are finding increasing roles in biotechnology for applications as contrast agents, probes, sensors, therapeutics and increasingly new value-added hybrid materials such as molecular logic devices. In most cases these materials must be conjugated to different types of biologicals such as proteins or DNA to accomplish this. However, most traditional methods of bioconjugation result in heterogeneous attachment and loss of activity. Bioorthogonal chemistries and in particular enzymatic labeling chemistries offer new strategies for catalyzing specific biomolecular attachment. We highlight current enzymatic labeling methods available for bioconjugating nanoparticles, some materials they have been used with, and how the resulting bioconjugates were applied. A discussion of the benefits and remaining issues associated with this type of bioconjugation chemistry and a brief perspective on how this field will develop is also provided.
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131
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Breger JC, Walper SA, Oh E, Susumu K, Stewart MH, Deschamps JR, Medintz IL. Quantum dot display enhances activity of a phosphotriesterase trimer. Chem Commun (Camb) 2015; 51:6403-6. [DOI: 10.1039/c5cc00418g] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Phosphotrisomerase trimer assembled on a quantum dot. This construct displays enhanced catalytic over freely diffusing enzyme and has potential to be spun into a fiber.
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132
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Cunningham PD, Khachatrian A, Buckhout-White S, Deschamps JR, Goldman ER, Medintz IL, Melinger JS. Resonance Energy Transfer in DNA Duplexes Labeled with Localized Dyes. J Phys Chem B 2014; 118:14555-65. [DOI: 10.1021/jp5065006] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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133
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Andrásfalvy BK, Galiñanes GL, Huber D, Barbic M, Macklin JJ, Susumu K, Delehanty JB, Huston AL, Makara JK, Medintz IL. Quantum dot-based multiphoton fluorescent pipettes for targeted neuronal electrophysiology. Nat Methods 2014; 11:1237-1241. [PMID: 25326662 PMCID: PMC4245189 DOI: 10.1038/nmeth.3146] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 08/22/2014] [Indexed: 11/09/2022]
Abstract
Targeting visually identified neurons for electrophysiological recording is a fundamental neuroscience technique; however, its potential is hampered by poor visualization of pipette tips in deep brain tissue. We describe quantum dot-coated glass pipettes that provide strong two-photon contrast at deeper penetration depths than those achievable with current methods. We demonstrated the pipettes' utility in targeted patch-clamp recording experiments and single-cell electroporation of identified rat and mouse neurons in vitro and in vivo.
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134
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Claussen JC, Daniele MA, Geder J, Pruessner M, Mäkinen AJ, Melde BJ, Twigg M, Verbarg JM, Medintz IL. Platinum-paper micromotors: an urchin-like nanohybrid catalyst for green monopropellant bubble-thrusters. ACS APPLIED MATERIALS & INTERFACES 2014; 6:17837-17847. [PMID: 25215632 DOI: 10.1021/am504525e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Platinum nanourchins supported on microfibrilated cellulose films (MFC) were fabricated and evaluated as hydrogen peroxide catalysts for small-scale, autonomous underwater vehicle (AUV) propulsion systems. The catalytic substrate was synthesized through the reduction of chloroplatinic acid to create a thick film of Pt coral-like microstructures coated with Pt urchin-like nanowires that are arrayed in three dimensions on a two-dimensional MFC film. This organic/inorganic nanohybrid displays high catalytic ability (reduced activation energy of 50-63% over conventional materials and 13-19% for similar Pt nanoparticle-based structures) during hydrogen peroxide (H2O2) decomposition as well as sufficient propulsive thrust (>0.5 N) from reagent grade H2O2 (30% w/w) fuel within a small underwater reaction vessel. The results demonstrate that these layered nanohybrid sheets are robust and catalytically effective for green, H2O2-based micro-AUV propulsion where the storage and handling of highly explosive, toxic fuels are prohibitive due to size-requirements, cost limitations, and close person-to-machine contact.
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135
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Algar WR, Stewart MH, Scott AM, Moon WJ, Medintz IL. Quantum dots as platforms for charge transfer-based biosensing: challenges and opportunities. J Mater Chem B 2014; 2:7816-7827. [DOI: 10.1039/c4tb00985a] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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136
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Buckhout-White S, Claussen JC, Melinger JS, Dunningham Z, Ancona MG, Goldman ER, Medintz IL. A triangular three-dye DNA switch capable of reconfigurable molecular logic. RSC Adv 2014. [DOI: 10.1039/c4ra10580j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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137
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Nazarenus M, Zhang Q, Soliman MG, del Pino P, Pelaz B, Carregal-Romero S, Rejman J, Rothen-Rutishauser B, Clift MJD, Zellner R, Nienhaus GU, Delehanty JB, Medintz IL, Parak WJ. In vitro interaction of colloidal nanoparticles with mammalian cells: What have we learned thus far? BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:1477-90. [PMID: 25247131 PMCID: PMC4168913 DOI: 10.3762/bjnano.5.161] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 08/12/2014] [Indexed: 05/20/2023]
Abstract
The interfacing of colloidal nanoparticles with mammalian cells is now well into its second decade. In this review our goal is to highlight the more generally accepted concepts that we have gleaned from nearly twenty years of research. While details of these complex interactions strongly depend, amongst others, upon the specific properties of the nanoparticles used, the cell type, and their environmental conditions, a number of fundamental principles exist, which are outlined in this review.
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Breger J, Delehanty JB, Medintz IL. Continuing progress toward controlled intracellular delivery of semiconductor quantum dots. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2014; 7:131-51. [PMID: 25154379 PMCID: PMC4345423 DOI: 10.1002/wnan.1281] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 04/21/2014] [Accepted: 05/28/2014] [Indexed: 01/22/2023]
Abstract
The biological applications of luminescent semiconductor quantum dots (QDs) continue to grow at a nearly unabated pace. This growth is driven, in part, by their unique photophysical and physicochemical properties which have allowed them to be used in many different roles in cellular biology including: as superior fluorophores for a wide variety of cellular labeling applications; as active platforms for assembly of nanoscale sensors; and, more recently, as a powerful tool to understand the mechanisms of nanoparticle mediated drug delivery. Given that controlled cellular delivery is at the intersection of all these applications, the latest progress in delivering QDs to cells is examined here. A brief discussion of relevant considerations including the importance of materials preparation and bioconjugation along with the continuing issue of endosomal sequestration is initially provided for context. Methods for the cellular delivery of QDs are then highlighted including those based on passive exposure, facilitated strategies that utilize peptides or polymers and fully active modalities such as electroporation and other mechanically based methods. Following on this, the exciting advent of QD cellular delivery using multiple or combined mechanisms is then previewed. Several recent methods reporting endosomal escape of QD materials in cells are also examined in detail with a focus on the mechanisms by which access to the cytosol is achieved. The ongoing debate over QD cytotoxicity is also discussed along with a perspective on how this field will continue to evolve in the future.
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139
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Breger JC, Sapsford KE, Ganek J, Susumu K, Stewart MH, Medintz IL. Detecting kallikrein proteolytic activity with peptide-quantum dot nanosensors. ACS APPLIED MATERIALS & INTERFACES 2014; 6:11529-11535. [PMID: 25003700 DOI: 10.1021/am502135h] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Contamination and adulterants in both naturally derived and synthetic drugs pose a serious threat to the worldwide medical community. Developing rapid and sensitive sensors/devices to detect these hazards is thus a continuing need. We describe a hydrophilic semiconductor quantum dot (QD)-peptide Förster resonance energy transfer (FRET) nanosensor for monitoring the activity of kallikrein, a key proteolytic enzyme functioning at the initiation of the blood clotting cascade. Kallikrein is also activated by the presence of an oversulfated contaminant recently found in preparations of the drug heparin. Quantitatively monitoring the activity of this enzyme within a nanosensor format has proven challenging because of inherent steric and kinetic considerations. Our sensor is designed around a central QD donor platform which displays controlled ratios of a modular peptidyl substrate. This peptide, in turn, sequentially expresses a terminal oligohistidine motif that mediates the rapid self-assembly of peptides to the QD surface, a linker-spacer sequence to extend the peptide away from the QD surface, a kallikrein recognized-cleavage site, and terminates in an acceptor dye-labeling site. Hydrophilic QDs prepared with compact, zwitterionic surface coatings were first evaluated for their ability to self-assemble the dye-labeled peptide substrates. An optimized two-step protocol was then utilized where high concentrations of peptide were initially digested with purified human kallikrein and samples collected at distinct time points were subsequently diluted into QD-containing solutions for assaying. This sensor provided a quantitative FRET-based readout for monitoring kallikrein activity and comparison to a calibration curve allowed estimation of the relevant Michaelis-Menten kinetic descriptors. The results further suggest that almost any protease should be amenable to a QD-based FRET assay format with appropriate design considerations.
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140
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Spillmann CM, Naciri J, Algar WR, Medintz IL, Delehanty JB. Multifunctional liquid crystal nanoparticles for intracellular fluorescent imaging and drug delivery. ACS NANO 2014; 8:6986-6997. [PMID: 24979226 DOI: 10.1021/nn501816z] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A continuing goal of nanoparticle (NP)-mediated drug delivery (NMDD) is the simultaneous improvement of drug efficacy coupled with tracking of the intracellular fate of the nanoparticle delivery vehicle and its drug cargo. Here, we present a robust multifunctional liquid crystal NP (LCNP)-based delivery system that affords facile intracellular fate tracking coupled with the efficient delivery and modulation of the anticancer therapeutic doxorubicin (Dox), employed here as a model drug cargo. The LCNPs consist of (1) a liquid crystal cross-linking agent, (2) a homologue of the organic chromophore perylene, and (3) a polymerizable surfactant containing a carboxylate headgroup. The NP core provides an environment to both incorporate fluorescent dye for spectrally tuned particle tracking and encapsulation of amphiphilic and/or hydrophobic agents for intracellular delivery. The carboxylate head groups enable conjugation to biologicals to facilitate the cellular uptake of the particles. Upon functionalization of the NPs with transferrin, we show the ability to differentially label the recycling endocytic pathway in HEK 293T/17 cells in a time-resolved manner with minimal cytotoxicity and with superior dye photostability compared to traditional organic fluorophores. Further, when passively loaded with Dox, the NPs mediate the rapid uptake and subsequent sustained release of Dox from within endocytic vesicles. We demonstrate the ability of the LCNPs to simultaneously serve as both an efficient delivery vehicle for Dox as well as a modulator of the drug's cytotoxicity. Specifically, the delivery of Dox as a LCNP conjugate results in a ∼40-fold improvement in its IC50 compared to free Dox in solution. Cumulatively, our results demonstrate the utility of the LCNPs as an effective nanomaterial for simultaneous cellular imaging, tracking, and delivery of drug cargos.
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141
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Scott AM, Algar WR, Stewart MH, Trammell SA, Blanco-Canosa JB, Dawson PE, Deschamps JR, Goswami R, Oh E, Huston AL, Medintz IL. Probing the Quenching of Quantum Dot Photoluminescence by Peptide-Labeled Ruthenium(II) Complexes. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2014; 118:9239-9250. [PMID: 24817922 PMCID: PMC4010286 DOI: 10.1021/jp501039w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/31/2014] [Indexed: 05/21/2023]
Abstract
Charge transfer processes with semiconductor quantum dots (QDs) have generated much interest for potential utility in energy conversion. Such configurations are generally nonbiological; however, recent studies have shown that a redox-active ruthenium(II)-phenanthroline complex (Ru2+-phen) is particularly efficient at quenching the photoluminescence (PL) of QDs, and this mechanism demonstrates good potential for application as a generalized biosensing detection modality since it is aqueous compatible. Multiple possibilities for charge transfer and/or energy transfer mechanisms exist within this type of assembly, and there is currently a limited understanding of the underlying photophysical processes in such biocomposite systems where nanomaterials are directly interfaced with biomolecules such as proteins. Here, we utilize redox reactions, steady-state absorption, PL spectroscopy, time-resolved PL spectroscopy, and femtosecond transient absorption spectroscopy (FSTA) to investigate PL quenching in biological assemblies of CdSe/ZnS QDs formed with peptide-linked Ru2+-phen. The results reveal that QD quenching requires the Ru2+ oxidation state and is not consistent with Förster resonance energy transfer, strongly supporting a charge transfer mechanism. Further, two colors of CdSe/ZnS core/shell QDs with similar macroscopic optical properties were found to have very different rates of charge transfer quenching, by Ru2+-phen with the key difference between them appearing to be the thickness of their ZnS outer shell. The effect of shell thickness was found to be larger than the effect of increasing distance between the QD and Ru2+-phen when using peptides of increasing persistence length. FSTA and time-resolved upconversion PL results further show that exciton quenching is a rather slow process consistent with other QD conjugate materials that undergo hole transfer. An improved understanding of the QD-Ru2+-phen system can allow for the design of more sophisticated charge-transfer-based biosensors using QD platforms.
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142
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Claussen JC, Hildebrandt N, Susumu K, Ancona MG, Medintz IL. Complex logic functions implemented with quantum dot bionanophotonic circuits. ACS APPLIED MATERIALS & INTERFACES 2014; 6:3771-8. [PMID: 24354314 DOI: 10.1021/am404659f] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We combine quantum dots (QDs) with long-lifetime terbium complexes (Tb), a near-IR Alexa Fluor dye (A647), and self-assembling peptides to demonstrate combinatorial and sequential bionanophotonic logic devices that function by time-gated Förster resonance energy transfer (FRET). Upon excitation, the Tb-QD-A647 FRET-complex produces time-dependent photoluminescent signatures from multi-FRET pathways enabled by the capacitor-like behavior of the Tb. The unique photoluminescent signatures are manipulated by ratiometrically varying dye/Tb inputs and collection time. Fluorescent output is converted into Boolean logic states to create complex arithmetic circuits including the half-adder/half-subtractor, 2:1 multiplexer/1:2 demultiplexer, and a 3-digit, 16-combination keypad lock.
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143
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Blanco-Canosa JB, Wu M, Susumu K, Petryayeva E, Jennings TL, Dawson PE, Algar WR, Medintz IL. Recent progress in the bioconjugation of quantum dots. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2013.08.030] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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144
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Algar WR, Kim H, Medintz IL, Hildebrandt N. Emerging non-traditional Förster resonance energy transfer configurations with semiconductor quantum dots: Investigations and applications. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2013.07.015] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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145
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Spillmann CM, Buckhout-White S, Oh E, Goldman ER, Ancona MG, Medintz IL. Extending FRET cascades on linear DNA photonic wires. Chem Commun (Camb) 2014; 50:7246-9. [DOI: 10.1039/c4cc01072h] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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146
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Wu M, Petryayeva E, Medintz IL, Algar WR. Quantitative measurement of proteolytic rates with quantum dot-peptide substrate conjugates and Förster resonance energy transfer. Methods Mol Biol 2014; 1199:215-239. [PMID: 25103812 DOI: 10.1007/978-1-4939-1280-3_17] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
An important challenge in biology is the development of probes for visualizing and quantitatively tracking enzyme activity. Proteases are an important class of enzyme with value as both diagnostic and therapeutic targets. In this chapter, we describe the preparation of quantum dot (QD)-peptide substrate conjugates as probes for measuring proteolytic activity. QDs have several highly advantageous optical properties that make these materials especially well suited for applications in bioanalysis and bioimaging. Further, peptide substrates for proteases can be controllably self-assembled to QDs and this capability, in combination with Förster resonance energy transfer (FRET), enables the design of quantitative in vitro assays capable of directly reporting on proteolytic activity. We present a detailed method for the preparation, calibration, and application of such QD probes, along with methods of analysis to generate progress curves for the proteolytic digestion of substrate. Representative data are illustrated for two different proteases and two different QD-fluorescent dye FRET pairs. The general methodology is likely to be applicable with other hydrolytic enzymes in addition to proteases. Overall, the method is straightforward to implement with commercially available materials and does not require specialized expertise.
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147
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Claussen JC, Algar WR, Hildebrandt N, Susumu K, Ancona MG, Medintz IL. Biophotonic logic devices based on quantum dots and temporally-staggered Förster energy transfer relays. NANOSCALE 2013; 5:12156-12170. [PMID: 24056977 DOI: 10.1039/c3nr03655c] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Integrating photonic inputs/outputs into unimolecular logic devices can provide significantly increased functional complexity and the ability to expand the repertoire of available operations. Here, we build upon a system previously utilized for biosensing to assemble and prototype several increasingly sophisticated biophotonic logic devices that function based upon multistep Förster resonance energy transfer (FRET) relays. The core system combines a central semiconductor quantum dot (QD) nanoplatform with a long-lifetime Tb complex FRET donor and a near-IR organic fluorophore acceptor; the latter acts as two unique inputs for the QD-based device. The Tb complex allows for a form of temporal memory by providing unique access to a time-delayed modality as an alternate output which significantly increases the inherent computing options. Altering the device by controlling the configuration parameters with biologically based self-assembly provides input control while monitoring changes in emission output of all participants, in both a spectral and temporal-dependent manner, gives rise to two input, single output Boolean Logic operations including OR, AND, INHIBIT, XOR, NOR, NAND, along with the possibility of gate transitions. Incorporation of an enzymatic cleavage step provides for a set-reset function that can be implemented repeatedly with the same building blocks and is demonstrated with single input, single output YES and NOT gates. Potential applications for these devices are discussed in the context of their constituent parts and the richness of available signal.
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148
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Stewart MH, Huston AL, Scott AM, Oh E, Algar WR, Deschamps JR, Susumu K, Jain V, Prasuhn DE, Blanco-Canosa J, Dawson PE, Medintz IL. Competition between Förster resonance energy transfer and electron transfer in stoichiometrically assembled semiconductor quantum dot-fullerene conjugates. ACS NANO 2013; 7:9489-505. [PMID: 24128175 DOI: 10.1021/nn403872x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Understanding how semiconductor quantum dots (QDs) engage in photoinduced energy transfer with carbon allotropes is necessary for enhanced performance in solar cells and other optoelectronic devices along with the potential to create new types of (bio)sensors. Here, we systematically investigate energy transfer interactions between C60 fullerenes and four different QDs, composed of CdSe/ZnS (type I) and CdSe/CdS/ZnS (quasi type II), with emission maxima ranging from 530 to 630 nm. C60-pyrrolidine tris-acid was first coupled to the N-terminus of a hexahistidine-terminated peptide via carbodiimide chemistry to yield a C60-labeled peptide (pepC60). This peptide provided the critical means to achieve ratiometric self-assembly of the QD-(pepC60) nanoheterostructures by exploiting metal affinity coordination to the QD surface. Controlled QD-(pepC60)N bioconjugates were prepared by discretely increasing the ratio (N) of pepC60 assembled per QD in mixtures of dimethyl sulfoxide and buffer; this mixed organic/aqueous approach helped alleviate issues of C60 solubility. An extensive set of control experiments were initially performed to verify the specific and ratiometric nature of QD-(pepC60)N assembly. Photoinitiated energy transfer in these hybrid organic-inorganic systems was then interrogated using steady-state and time-resolved fluorescence along with ultrafast transient absorption spectroscopy. Coordination of pepC60 to the QD results in QD PL quenching that directly tracks with the number of peptides displayed around the QD. A detailed photophysical analysis suggests a competition between electron transfer and Förster resonance energy transfer from the QD to the C60 that is dependent upon a complex interplay of pepC60 ratio per QD, the presence of underlying spectral overlap, and contributions from QD size. These results highlight several important factors that must be considered when designing QD-donor/C60-acceptor systems for potential optoelectronic and biosensing applications.
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Algar WR, Medintz IL. Concentric energy transfer with quantum dots for multiplexed biosensing. NANO REVIEWS 2013; 4:22428. [PMID: 24020009 PMCID: PMC3763064 DOI: 10.3402/nano.v4i0.22428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Spillmann CM, Ancona MG, Buckhout-White S, Algar WR, Stewart MH, Susumu K, Huston AL, Goldman ER, Medintz IL. Achieving effective terminal exciton delivery in quantum dot antenna-sensitized multistep DNA photonic wires. ACS NANO 2013; 7:7101-7118. [PMID: 23844838 DOI: 10.1021/nn402468t] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Assembling DNA-based photonic wires around semiconductor quantum dots (QDs) creates optically active hybrid architectures that exploit the unique properties of both components. DNA hybridization allows positioning of multiple, carefully arranged fluorophores that can engage in sequential energy transfer steps while the QDs provide a superior energy harvesting antenna capacity that drives a Förster resonance energy transfer (FRET) cascade through the structures. Although the first generation of these composites demonstrated four-sequential energy transfer steps across a distance >150 Å, the exciton transfer efficiency reaching the final, terminal dye was estimated to be only ~0.7% with no concomitant sensitized emission observed. Had the terminal Cy7 dye utilized in that construct provided a sensitized emission, we estimate that this would have equated to an overall end-to-end ET efficiency of ≤ 0.1%. In this report, we demonstrate that overall energy flow through a second generation hybrid architecture can be significantly improved by reengineering four key aspects of the composite structure: (1) making the initial DNA modification chemistry smaller and more facile to implement, (2) optimizing donor-acceptor dye pairings, (3) varying donor-acceptor dye spacing as a function of the Förster distance R0, and (4) increasing the number of DNA wires displayed around each central QD donor. These cumulative changes lead to a 2 orders of magnitude improvement in the exciton transfer efficiency to the final terminal dye in comparison to the first-generation construct. The overall end-to-end efficiency through the optimized, five-fluorophore/four-step cascaded energy transfer system now approaches 10%. The results are analyzed using Förster theory with various sources of randomness accounted for by averaging over ensembles of modeled constructs. Fits to the spectra suggest near-ideal behavior when the photonic wires have two sequential acceptor dyes (Cy3 and Cy3.5) and exciton transfer efficiencies approaching 100% are seen when the dye spacings are 0.5 × R0. However, as additional dyes are included in each wire, strong nonidealities appear that are suspected to arise predominantly from the poor photophysical performance of the last two acceptor dyes (Cy5 and Cy5.5). The results are discussed in the context of improving exciton transfer efficiency along photonic wires and the contributions these architectures can make to understanding multistep FRET processes.
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