Plasmon Resonance Energy Transfer Research Articles

Random lasers with controlled emission modes by colloidal semiconductor quantum dots coupled to plasmonic nanorod arrays

Random lasers based on scattering for light amplification have gained extensive attention due to their simple structures. Colloidal semiconductor quantum dots (CSQDs) are excellent candidates as active media for random lasing. However, achieving CSQDs-based random lasers is challenging because the non-radiative Auger recombination produces a remarkable carrier loss. Here, we report random lasers with low thresholds based on the CSQDs coupled to the plasmonic nanorod arrays. The random lasers result from the enhancing excitation and emission rates of the CSQDs through plasmon resonance energy transfer induced by the spectral overlap between the resonant cavity modes of the plasmonic nanorod arrays and the excitons of the CSQDs, which reduces the carrier loss and establishes the optical gain in the CSQDs. Moreover, the incoherent and coherent emission modes can be controlled by varying the filling configurations (i.e., full-filling and partial-filling) of the plasmonic nanorods embedded in anodic aluminum oxide templates. Consequently, the incoherent random laser with a threshold of 19.3 μJ/mm2 and coherent random lasers with a threshold of 13.5 μJ/mm2 are performed, respectively. The proposed system provides a feasible method for low-threshold CSQDs-based random lasers with controlled emission modes, showing a promising avenue for potential applications.

Plasmons Enhancing Sub-Bandgap Photoconductivity in TiO2 Nanoparticles Film.

The coupling between sub-bandgap defect states and surface plasmon resonances in Au nanoparticles and its effects on the photoconductivity performance of TiO2 are investigated in both the ultraviolet (UV) and visible spectrum. Incorporating a 2 nm gold nanoparticle layer in the photodetector device architecture creates additional trapping pathways, resulting in a faster current decay under UV illumination and a significant enhancement in the visible photocurrent of TiO2, with an 8-fold enhancement of the defects-related photocurrent. We show that hot electron injection (HEI) and plasmonic resonance energy transfer (PRET) jointly contribute to the observed photoconductivity enhancement. In addition to shedding light on the below-band-edge photoconductivity of TiO2, our work provides insight into new methods to probe and examine the surface defects of metal oxide semiconductors using plasmonic resonances.

Squeezed Protons and Infrared Plasmonic Resonance Energy Transfer.

Unusual nuclear quantum effects may emerge near noble metal nanostructures such as squeezed vibrational states in molecular junctions and plasmonic resonance energy transfer in the infrared domain. Herein, nuclear quantum effects near heavy metals are studied by nuclear-electronic orbital density functional theory (NEO-DFT) with an effective core potential. For a quantum proton sandwiched between a pair of gold tips modeled by two Au6 clusters, NEO-DFT calculations suggest that the quantum proton density can be squeezed as the tip distance decreases. For an HF molecule placed near a one-dimensional Au nanowire composed of up to 34 Au atoms, real-time NEO time-dependent density functional theory (RT-NEO-TDDFT) shows that the infrared plasmonic motion within the Au nanowire may resonantly transfer electronic energy to the HF proton vibrational stretch mode. Overall, these calculations illustrate the advantages of the NEO approach for probing nuclear quantum effects, such as squeezed proton vibrational states and infrared plasmonic resonance energy transfer.

Temperature-sensitive metal-enhanced fluorescence and plasmon resonance energy transfer.

Experimental decoupling of the effects of plasmon resonance energy transfer (PRET) and metal-enhanced fluorescence (MEF) within the same nanometal-fluorophore pair is fascinating but challenging. In this study, we presented a possible solution for this by coating plasmonic Au nanoparticles (AuNPs) with temperature-sensitive poly(N-isopropylacrylamide) (pNIPAM) shells and R6G hybrids, termed the Au@p-R nanoplatform, which could reversibly adjust the separation between dyes and the AuNP surface, enabling an ON/OFF switch between MEF and PRET. In our optimization process, we discovered that 20 kDa of pNIPAM causes an MEF effect owing to an appropriate shrinking distance of 6.86 ± 0.85 nm. This dual-model nanoplatform exhibits great potential for tracking temperature-dependent transitions.

Boosting photocatalytic hydrogen production of CdS/BiVO4 nanoplates by transferring in-plane plasmon resonant energy of gold nanoparticles

The in-plane plasmon resonant energy transfer (PRET) effect from gold significantly boosts the hydrogen evolution of the Z-scheme CdS/BiVO4 photocatalyst.

Influence of gold nanostructures on excited state intramolecular proton transfer in multidomain HTTH dye

Organic multidomain dyes exhibiting excited state intramolecular proton transfer (ESIPT) are known due to large Stokes shifts and dependence of their luminescence spectral characteristics on the properties of the environment. In this work, influence of gold nanostructures on the spectral characteristics of a “polycarbonate matrix – gold nanostructures – HTTH” system was studied using thiazole dye HTTH as an example. A hypothesis about the possibility of plasmon resonance energy transfer (PRET) between the HTTH molecules in different states, namely the ground state (enol form) and the state after proton transfer (keto form), mediated by gold nanostructures was experimentally tested. Presence of gold nanostructures in the vicinity of HTTH molecules was found to lead to the changes in the ratio of the luminescence peak intensities for the enol and keto form of these molecules. This phenomenon opens up the possibility of additional regulation of the spectral characteristics and may evidence the PRET effect in the systems containing ESIPT-exhibiting dyes and plasmonic nanostructures. The obtained results improve our understanding of the physical processes in the systems similar to the studied one and imply new practical applications of them such as fabrication of organic light-emitting diodes, sensors, super-resolution microscopy tools and ultraviolet-to-visible radiation convertors.

Photocatalytic Water Splitting Driven by Surface Plasmon Resonance

AbstractSurface plasmon resonance (SPR) in metals results in unique optical properties and photoelectric functions, which are helpful for light harvesting in photocatalysis. Additionally, the plasmon‐associated charge transfer process gives a complementary platform to understand the charge dynamics at a fundamental level. This Review focused on the recent developments of water splitting by plasmonic metals/semiconductor photocatalysts. Firstly, the basic characteristics of SPR and the plasmon‐enhanced photocatalysis mechanisms including plasmon resonance energy transfer and interfacial charge transfer are introduced, highlighting the recent understanding of the plasmonic electron‐hole separation, distribution, and the reaction sites for water splitting. Then, advances in the strategies to improve the quantum efficiency of plasmon‐induced water splitting are summarized by considering modulation in metals, interface contacts, and bulk properties of semiconductors. Finally, we discuss future prospects in the development of high‐efficiency plasmonic metal/semiconductor photocatalysts for water splitting.

Plasmon Resonance Energy Transfer Nanoruler for Pinpointing Molecular Distance and Interaction on the Living Cell Membrane.

Developing novel strategies to measure nanoscale distance and molecular interaction on a living cell membrane is of great significance but challenging. Here we develop a model of a linker-free plasmon resonance energy transfer, termed "PRET nanoruler", which is composed of a single-sized nanogold-antibody conjugates donor (G26@antiCD71) and a fluorophore-labeled XQ-2d aptamer receptor (XQ-2d-Cy3), that produces a separation distance (r) dependent energy transfer (ηPRET). Both the theoretical finite element simulation and experiments evidence the observable PRET between single G26NPs and XQ-2d-Cy3. Regardless of the size of ηPRET, we could confirm r is less than 5 nm, the separation of two binding sites is in the range of 13.0-18.0 nm. There is a competitive binding of Tf and XQ-2d-Cy3 on CD71 receptors. PRET nanoruler realizes the estimation of the nanoscale separation distance, and determines the molecular interaction and competitive binding. It is an alternative tool for observing nanoscale single molecular events in the future.

Metasurfaces-Driven Hyperspectral Imaging via Multiplexed Plasmonic Resonance Energy Transfer.

Obtaining single-molecular-level fingerprints of biomolecules and electron-transfer dynamic imaging in living cells are critically demanded in postgenomic life sciences and medicine. However, the possible solution called plasmonic resonance energy transfer (PRET) spectroscopy remains challenging due to the fixed scattering spectrum of a plasmonic nanoparticle and limited multiplexing. Here, multiplexed metasurfaces-driven PRET hyperspectral imaging, to probe biological light-matter interactions, is reported. Pixelated metasurfaces with engineered scattering spectra are first designed over the entire visible range by the precision nanoengineering of gap plasmon and grating effects of metasurface clusters. Pixelated metasurfaces are created and their full dark-field coloration is optically characterized with visible color palettes and high-resolution color printings of the art pieces. Furthermore, three different biomolecules (i.e., chlorophyll a, chlorophyll b, and cytochrome c) are applied on metasurfaces for color palettes to obtain selective molecular fingerprint imaging due to the unique biological light-matter interactions with application-specific biomedical metasurfaces. This metasurface-driven PRET hyperspectral imaging will open up a new path for multiplexed real-time molecular sensing and imaging methods.

Single-Particle Plasmonic Sensing of Nitric Oxide in Living Cells.

Plasmon resonance energy transfer (PRET), which occurs between plasmonic nanoparticles (NPs) and organic dyes, shows significant potential in sensing chemistry due to its high sensitivity at the single-particle level. In this work, a PRET-based sensing strategy was presented for the ultrasensitive sensing of nitric oxide (NO) in living cells. Supramolecular cyclodextrin (CD) molecules that exhibited different binding abilities to various molecules due to its unique rigid structure and annular cavity was applied and modified on gold NPs (GNPs) to construct the PRET nanosensors. NO-reactive molecules, rhodamine B-derived molecules (RdMs), were further inserted into the cavity of CD molecules through hydrophobic interactions to form host-guest structures. In the presence of NO, RdMs reacted with the target and generated rhodamine (RdB). Due to the spectral overlap between GNPs@CD and RdB molecules, PRET occurred and further led to a decrease in the scattering intensity of GNPs@CD, which was sensitive to the concentration of NO. The proposed sensing platform not only provides quantitative detection of NO in solution but also realized the single-particle imaging analysis of exogenous and endogenous NO in living cells. The single-particle plasmonic probes exhibit great potential in the in vivo sensing of biomolecules and metabolic processes.

AgCu/TiO2 hot-electron device for solar water splitting: the mechanisms of LSPR and time-domain characterization

More and more metal/semiconductor nanostructures have been served as a hot-electron device with the localized surface plasmonic resonance (LSPR) effect to boost hydrogen evolution from solar water splitting. In this work, bimetallic AgCu with optimal ratio are deposited onto TiO2 nanopore/nanotube arrays to construct AgCu/TiO2 photoanode for photoelectrochemical water splitting, a novel simulation characterization to visualize the LSPR process is proposed. The near electric field enhancement and plasmon resonance energy transfer mechanisms of single Ag and Cu are inferred by time-domain characterization, illustrating the contradictory photocurrent under AM 1.5 illumination with its LSPR effect based on the particle size. The variation of local electric field over time within the interfaces of AgCu bimetals and bimetal/TiO2 models reveals the migration of hot electrons from Ag into Cu and the synergetic effect of different LSPR mechanisms. The resulting higher photoelectrochemical activities of AgCu/TiO2 also verifies the positive roles of the coexistence of AgCu on electron generation and energy transfer to interband excitation of TiO2.

Significantly boosted photoelectrochemical water splitting performance by plasmonic enhanced Hematite@MOF composite photoelectrodes

Hematite as a catalyst for photoelectrochemical water splitting offers huge potential, due to its high chemical stability, great abundance, and low cost. However, the low water oxidation kinetics and poor charge transportation have hindered progress towards the manufacture of practical water splitting devices. To tackle these problems, a visible light responsive metal-organic framework (MOF) polyhedral zeolitic imidazolate (ZIF-67), and optimised plasmonic Ag nanorods were incorporated into hematite nanostructures to form a three-component heterojunction photoelectrode. The designed photoanode showed dramatically improved light harvesting in the visible range and enhanced charge transport. A mechanistic investigation allowed the deconvolution of the enhanced performance pathways. First, the Hematite@ZIF-67 core-shell p-n junction enables facile charge carrier transfer between ZIF-67 and hematite. In addition, ZIF-67 also provides active sites for water oxidation and boosts surface oxygen evolution reaction (OER) kinetics. Guided by finite-difference time-domain (FDTD) modelling, Ag nanorods with optimised aspect ratio were incorporated between ZIF-67 and hematite. The Ag nanorods facilitate broadband light absorption and surface charge injection, induced by near-field excitation enhancement and plasmonic resonance energy transfer (PRET) pathways. The design and addition of ZIF-67 and Ag nanorods result in superior performance for a hematite-based photoanode for photoelectrochemical (PEC) water oxidation.

Toward Smart Sensing by MXene.

The Internet of Things era has promoted enormous research on sensors, communications, data fusion, and actuators. Among them, sensors are a prerequisite for acquiring the environmental information for delivering to an artificial data center to make decisions. The MXene-based sensors have aroused tremendous interest because of their extraordinary performances. In this review, the electrical, electronic, and optical properties of MXenes are first introduced. Next, the MXene-based sensors are discussed according to the sensing mechanisms such as electronic, electrochemical, and optical methods. Initially, biosensors are introduced based on chemiresistors and field-effect transistors. Besides, the wearable pressure sensor is demonstrated with piezoresistive devices. Third, the electrochemical methods include amperometry and electrochemiluminescence as examples. In addition, the optical approaches refer to surface plasmonic resonance and fluorescence resonance energy transfer. Moreover, the prospects are delivered of multimodal data fusion toward complicated human-like senses. Eventually, future opportunities for MXene research are conveyed in the new material discovery, structure design, and proof-of-concept devices.

Single-particle detection of cholesterol based on the host-guest recognition induced plasmon resonance energy transfer

Plasmon resonance energy transfer (PRET) occurs between the plasmonic nanoparticles (NPs) and organic dyes forming donor-acceptor pairs, which has great potential in quantitative analytical chemistry because of its excellent sensitivity under dark-field microscopy (DFM). Herein, we introduce supramolecular β-cyclodextrin (β-CD) to design a host-guest recognition plasmonic nano-structure modified gold nanoparticles (GNPs), while GNPs and rhodamine molecule (RB) act as the donor and acceptor, respectively. In the presence of the target cholesterol, due to the stronger binding of cholesterol with β-CD, RB molecules are released, inducing the inhibition of PRET, as well as the increase of the scattering intensity of GNPs. The proposed strategy achieves a linear range from 0.02 µmol/L to 2.0 µmol/L for cholesterol detection, and reaches a limit of detection (LOD) of 6.7 nmol/L. This host-guest recognition strategy can easily integrate receptor-donor pair into one nanoparticle, which simplifies the construction of the PRET platform, and further provides an effective approach for PRET-based analytical applications. Afterwards, the proposed PRET strategy was successfully applied for the detection of cholesterol in serum samples with high sensitivity and specificity. The proposed method provides an effective clinically potential means for the detection of cholesterol and other disease-related biomarkers.

Quantum Electrodynamic Behavior of Chlorophyll in a Plasmonic Nanocavity.

Plasmonic nanocavities have been used as a novel platform for studying strong light-matter coupling, opening access to quantum chemistry, material science, and enhanced sensing. However, the biomolecular study of cavity quantum electrodynamics (QED) is lacking. Here, we report the quantum electrodynamic behavior of chlorophyll-a in a plasmonic nanocavity. We construct an extreme plasmonic nanocavity using Au nanocages with various linker molecules and Au mirrors to obtain a strong coupling regime. Plasmon resonance energy transfer (PRET)-based hyperspectral imaging is applied to study the electrodynamic behaviors of chlorophyll-a in the nanocavity. Furthermore, we observe the energy level splitting of chlorophyll-a, similar to the cavity QED effects due to the light-matter interactions in the cavity. Our study will provide insight for further studies in quantum biological electron or energy transfer, electrodynamics, the electron transport chain of mitochondria, and energy harvesting, sensing, and conversion in both biological and biophysical systems.

Inner-Membrane-Bound Gold Nanoparticles as Efficient Electron Transfer Mediators for Enhanced Mitochondrial Electron Transport Chain Activity.

Electron transfer through the mitochondrial electron transport chain (ETC) can be critically blocked by the dysfunction of protein complexes. Redox-active molecules have been used to mediate the electron transfer in place of the dysfunctional complexes; however, they are limited to replacing complex I and are known to be toxic. Here we report artificial mitochondrial electron transfer pathways that enhance ETC activity by exploiting inner-membrane-bound gold nanoparticles (GNPs) as efficient electron transfer mediators. The hybridization of mitochondria with GNPs, driven by electrostatic interaction, is successfully visualized in real time at the level of a single mitochondrion. By observing quantized quenching dips via plasmon resonance energy transfer, we reveal that the hybridized GNPs are bound to the inner membrane of mitochondria irrespective of the presence of the outer membrane. The ETC activity of mitochondria with GNPs such as membrane potential, oxygen consumption, and ATP production is remarkably increased in vitro.

Exploring plasmons weakly coupling to perovskite excitons with tunable emission by energy transfer

Localized surface plasmon resonance (LSPR) has caused extensive concern and achieved widespread applications in optoelectronics. However, the weak coupling of plasmons and excitons in a nanometal/semiconductor system remains to be investigated via energy transfer. Herein, bandgap tunable perovskite films were synthesized to adjust the emission peaks, for further coupling with stable localized surface plasmons from gold nanoparticles. The degree of mismatch, using steady-state and transient photoluminescence (PL), was investigated systematically in two different cases of gold nanoparticles that were in direct contacting and insulated. The results demonstrated the process of tuning emission coupled to LSPR via wavelength-dependent photoluminescence intensity in the samples with an insulating spacer. In the direct contact case, the decreased radiative decay rate involves rapid plasmon resonance energy transfer to the perovskite semiconductor and non-radiative energy transfer to metal nanoparticles in the near-field range.

Magnetofluoro-Immunosensing Platform Based on Binary Nanoparticle-Decorated Graphene for Detection of Cancer Cell-Derived Exosomes.

Multi-functionalized carbon nanomaterials have attracted interest owing to their excellent synergic properties, such as plasmon resonance energy transfer and surface-enhanced Raman scattering. Particularly, nanoparticle (NP)-decorated graphene (GRP) has been applied in various fields. In this study, silver NP (AgNP)- and magnetic iron oxide NP (IONP)-decorated GRP were prepared and utilized as biosensing platforms. In this case, AgNPs and GRP exhibit plasmonic properties, whereas IONPs exhibit magnetic properties; therefore, this hybrid nanomaterial could function as a magnetoplasmonic substrate for the magnetofluoro-immunosensing (MFI) system. Conversely, exosomes were recently considered high-potential biomarkers for the diagnosis of diseases. However, exosome diagnostic use requires complex isolation and purification methods. Nevertheless, we successfully detected a prostate-cancer-cell-derived exosome (PC-exosome) from non-purified exosomes in a culture media sample using Ag/IO-GRP and dye-tetraspanin antibodies (Ab). First, the anti-prostate-specific antigen was immobilized on the Ag/IO-GRP and it could isolate the PC-exosome from the sample via an external magnetic force. Dye-tetraspanin Ab was added to the sample to induce the sandwich structure. Based on the number of exosomes, the fluorescence intensity from the dye varied and the system exhibited highly sensitive and selective performance. Consequently, these hybrid materials exhibited excellent potential for biosensing platforms.

Ultrasensitive and real-time optical detection of cellular oxidative stress using graphene-covered tunable plasmonic interfaces

Reactive oxygen species (ROS) regulate various physiological and pathological conditions in cells by interacting with signaling molecules and inducing oxidative stress. Therefore, sensitive monitoring of ROS levels in living cells is important to track cellular state and study the complex role of ROS in the development of various pathologies. Herein, we present an optically tunable plasmonic interface covered with graphene to monitor cellular ROS levels with superior sensitivity and cellular comfortability. As a sensing principle, we employed plasmon resonance energy transfer (PRET)-based spectral quenching dips modulated by redox-active cytochrome c for real-time monitoring. By transferring graphene layers to plasmonic nanoparticles immobilized on a glass substrate, the scattering profiles of the nanoprobes were adjusted in terms of the position, width, and intensity of the peaks to determine the optimal conditions for measuring the PRET signal. Using the optimized graphene-covered plasmonic nanoprobe, we obtained calibration curves over a wide concentration range from femtomoles to millimoles for hydrogen peroxide based on the change in the PRET signal. Before monitoring cellular ROS, we confirmed that a high density of cells adhered well to the graphene-covered plasmonic interface by observing immunofluorescence images of the cytoskeleton of the immobilized cells. Finally, we monitored the real-time ROS generated by the cells under oxidative stress conditions by directly measuring the spectral changes of the probes around the cells. We believe that the proposed graphene-covered tunable plasmonic interface has versatile applicability for investigating cellular stress and disease progression by monitoring ROS levels under various cellular conditions.

Selective ultrasensitive FBG-SBL chemosensor for detection of copper ions in water resources based on plasmon resonance energy transfer

In this study, the gold (Au) coated fiber Bragg grating (FBG) probe decorated with Schiff base ligands (SBL) with variable denticity is proposed as a susceptible sensor for monitoring the copper ions (Cu2+) concentration in an aqueous solution. The sensing principle can be attributed to the interaction of the SBL coated on Au/FBG, which serves as anionic chelates with Cu2+, altering the environment refractive index and changing the surface plasmon resonance (SPR) condition. The sensitivity and limit of detection (LOD) through a Bragg wavelength shift are measured to be 23.1 pm/µM and 0.07 µM respectively, with a dynamic range of up to 4 µM (µM, 2.5 ppm), which is within the acceptable limit specified by the World Health Organization (WHO) for safe drinking water (1.3 ppm). The probe shows an assertive coordination behaviour towards Cu2+ for selective detection compared to other heavy metals. Excellent reusability (6 trial times) and specificity and portability make FBG-SBL chemosensor suitable for online monitoring of water resources.