Multishell Nanoparticles Research Articles

Bone‐Targeting and Multishelled Oral Eldecalcitol Nanoparticles Improve Osteoporosis by Reconstruction of Osteogenic‐Osteoclastic Homeostasis

AbstractCurrent treatment of postmenopausal osteoporosis (PMOP) focuses on systemic administration of medication, neglecting to proactively modulate the local microenvironment of skeletal system for superior therapeutic performance. Eldecalcitol (ED‐71), a novel drug for treating osteoporosis, still requires research to overcome high‐frequency delivery and low‐utilization. Here, a bone‐targeting and multishelled nanoparticles are developed for step‐wise release of ED‐71. The nanoparticles are achieved by using the chitosan/alginate outer layer as protective barrier against gastric acid, pectin middle layer as adhesive agent that improved intestinal penetration, and ethylene diamine tetraacetic acid‐grafted mesoporous silica nanomaterials core as bone‐targeting nanocarriers. After oral administration, the ED‐71‐loaded nanoparticles (ME‐ED‐71@PCA) promotes osteogenic differentiation of bone marrow mesenchymal stem cells by reducing intracellular oxidative stress, and inhibits the osteoclast differentiation. ME‐ED‐71@PCA improves bone mass in ovariectomized‐mice by promoting osteogenesis and inhibiting osteoclastogenesis, and the efficacy is more pronounced than ED‐71 alone. ME‐ED‐71@PCA exhibits satisfactory therapeutic performance due to its step‐wise drug release and bone‐targeting compared to ED‐71 administration, providing a new approach to re‐establish bone metabolic homeostasis in PMOP.

(Invited) Manipulating Light Emission from Rare Earth Doped Nanoparticles for Applications in Theranostics

Luminescent nanomaterials that can be excited, as well as emit, in the near-infrared (NIR) have been investigated for use in a plethora of applications including nanomedicine, nanoelectronics, biosensing, bioimaging, photovoltaics, photocatalysis, etc. The use of NIR light for excitation mitigates some of the drawbacks associated with high-energy (UV or blue) excitation, for example, little to no background autofluorescence from the specimen under investigation as well as no incurred photodamage. Moreover, one of the biggest limitations is of course, that of penetration. As such, NIR light can penetrate tissues much better than high-energy light especially when these wavelengths lie within the three biological windows (BW-I: 700-950, BW-II: 1000-1350, BW-III: 1550-1870 nm) where tissues are optically transparent. At the forefront of NIR excited nanomaterials are rare earth doped nanoparticles, which due to their 4f electronic energy states can undergo conventional (Stokes) luminescence and emit in the three NIR biological windows. However, unlike other classes of nanoparticles, they can also undergo a multiphoton process (known as upconversion) where the NIR excitation light is converted to higher energies resulting in anti-Stokes luminescence spanning the UV-visible-NIR regions. Perhaps the biggest impact of such materials would be in the field of disease diagnostics and therapeutics, now commonly referred to as theranostics. Due to the versatility of their optical properties, it now becomes possible to generate high-energy light (UV or blue) in situ to trigger other light activated therapeutic modalities (i.e. drug release) while using the NIR emission for diagnostics (i.e. bioimaging, nanothermometry). Here, we present the synthesis of various NIR excited (and emitting) rare earth doped core/shell (and multishell) nanoparticles and demonstrate how their luminescence properties can be exploited for potential use in diverse biomedical applications.

Plasmonic Multi-Layered Built-in Hotspots Nanogaps for Effectively Activating Analytes.

Multi-layered plasmonic nanostructures are able to highly promote the near-field confinement and effectively activate analytes, which are of predominate significance but are extremely challenging. Herein, the semi-open Au core@carved AuAg multi-shell superstructure nanoparticles(multi-Au@Ag-Au NPs, multi = mono, bi, tri, tetra, and penta) are reported with a high designability on electromagnetic field and capability of effectively capturing analytes. By controlling synthetic parameters such as the number of galvanic exchange and Ag growth, multi-Au@Ag-Au NPs are successfully obtained, with tunable layer numbers and asymmetric nanoholes. Due to collective plasmon oscillations of multi-layered built-in nanogaps, the electromagnetic field strength of a single penta-Au@Ag-Au entity reach 48841. More importantly, the penta-Au@Ag-Au NPs show a remarkable light-harvesting capability, which is adaptive to different Raman lasers, supporting high-diversity detection. Additionally, the structural specificity allows analytes to be sufficiently captured into interior hotspots, and further achieve highly sensitive detection with limit of detection down to 3.22 × 10-12 M. This study not only provides an effective pathway for integrating abundant hotspots and activating target molecules in single plasmonic superstructure, but stimulates advancements in SERS substrates for various applications.

Functionalized calcium phosphate nanoparticles to direct osteoprotegerin to bone lesion sites in a medaka (Oryzias latipes) osteoporosis model.

Calcium phosphate (CaP) is the inorganic part of hard tissues, such as bone, teeth and tendons, and has a high biocompatibility and good biodegradability. Therefore, CaP nanoparticles functionalized with DNA encoding bone anabolic factors are promising carrier-systems for future therapeutic development. Here, we analysed CaP nanoparticles in a genetically modified medaka fish model, where osteoporosis-like lesions can be induced by transgenic expression of receptor activator of nuclear factor kappa-B ligand (Rankl). Rankl-transgenic medaka were used to visualize and understand effects of microinjected functionalized CaP nanoparticles during modulation of osteoclast activity in vivo. For this, we synthetized multi-shell CaP nanoparticles by rapid precipitation of calcium lactate and ammonium hydrogen phosphate followed by the addition of plasmid DNA encoding the osteoclastogenesis inhibitory factor osteoprotegerin-b (Opgb). An additional layer of poly(ethyleneimine) was added to enhance cellular uptake. Integrity of the synthesized nanoparticles was confirmed by dynamic light scattering, scanning electron microscopy and energy dispersive X-ray spectroscopy. Fluorescently labelled CaP nanoparticles were microinjected into the heart, trunk muscle or caudal fins of Rankl-transgenic medaka embryos that expressed fluorescent reporters in various bone cell types. Confocal time-lapse imaging revealed a uniform distribution of CaP nanoparticles in injected tissues and showed that nanoparticles were efficiently taken up by macrophages that subsequently differentiated into bone-resorbing osteoclasts. After Rankl induction, fish injected with Opg-functionalized nanoparticles showed delayed or absent degradation of mineralized matrix, i.e. a lower incidence of osteoporosis-like phenotypes. This is proof of principle that CaP nanoparticles can be used as carriers to efficiently deliver modulatory compounds to osteoclasts and block their activity.

Multi-shell structured upconversion nanocarriers that combine IDO inhibitor-induced immunotherapy with NIR-triggered photodynamic therapy for deep tumors.

Combination therapies for cancer have attracted substantial research interest as an emerging treatment strategy that can reduce the chance of cancer resistance to chemotherapy and deal effectively with cancer cell heterogeneity. In this study, we designed novel nanocarriers that combine immunotherapy, which attacks tumors by stimulating the immune system, with photodynamic therapy (PDT), a non-invasive phototherapy that can selectively destroy only cancer cells. Multi-shell structured upconversion nanoparticles (MSUCNs) with good photoluminescence (PL) strength were synthesized for a combination therapy of near-infrared (NIR) light-induced PDT and immunotherapy using a specific immune checkpoint inhibitor. By optimizing the doping content of ytterbium ions (Yb3+) and forming a multi-shell structure, MSUCNs able to emit light at multiple wavelengths with the PL efficiency improved by 260-380 times compared to core particles were synthesized. Then, the surfaces of the MSUCNs were modified with folic acid (FA) as a tumor-targeting ligand, Ce6 as a photosensitizer (PS), and 1-methyl-tryptophan (1MT) as an indoleamine 2,3-dioxygenase (IDO) inhibitor. The FA-, Ce6-, and 1MT-conjugated MSUCNs (F-MSUCN3-Ce6/1MT) exhibited targeted cellular uptake by active targeting against HeLa cells, which are FA receptor-positive cancer cells. Upon irradiation with NIR at 808 nm, the F-MSUCN3-Ce6/1MT nanocarriers produced reactive oxygen species, which caused apoptosis of the cancer cells, and activated CD8+ T cells, which enhanced the immune response by binding with immune checkpoint inhibitory proteins and blocking the IDO pathway. Therefore, these F-MSUCN3-Ce6/1MT nanocarriers could be potential candidate materials for synergistic anticancer therapy that combines IDO inhibitor-based immunotherapy with enhanced NIR-triggered PDT.

Melting of FePt nanoparticles studied using DFT.

Thermodynamical stability of different variants of FePt nanoparticles has been studied using DFT molecular dynamics. The melting temperature and general stability at elevated temperatures have been estimated from both energy difference and atomic root-mean-square displacement functions. The investigated systems include multi-shell nanoparticles of iron and platinum with icosahedral symmetry and a magic number of atoms (55): iron-terminated Fe43Pt12 and platinum-terminated Fe12Pt43. Additionally, the cuboctahedral Fe24Pt31 particle, cleaved-out of the bulk structure, has been studied using the same procedure. Molecular dynamics simulations have been performed for a range of temperatures reaching above the melting points. The calculations confirmed high structural instability of the Fe-terminated nanoparticles and a strong stabilizing effect of the Pt-termination in the shell-type icosahedral particles. The advantage of the presented study is the self-consistency of the nanoparticle band structure in each time step, including magnetic interactions among local magnetic moments.

(Invited) Rare Earth Doped Nanoparticles

Luminescent nanomaterials that can be excited, as well as emit, in the near-infrared (NIR) have been investigated for use in a plethora of applications including nanomedicine, nanoelectronics, biosensing, bioimaging, photovoltaics, photocatalysis, etc. The use of NIR light for excitation mitigates some of the drawbacks associated with high-energy (UV or blue) excitation, for example, little to no background autofluorescence from the specimen under investigation as well as no incurred photodamage. Moreover, one of the biggest limitations is of course, that of penetration. As such, NIR light can penetrate tissues much better than high-energy light especially when these wavelengths lie within the three biological windows (BW-I: 700-950, BW-II: 1000-1350, BW-III: 1550-1870 nm) where tissues are optically transparent. At the forefront of NIR excited nanomaterials are rare earth doped nanoparticles, which due to their 4f electronic energy states can undergo conventional (Stokes) luminescence and emit in the three NIR biological windows. However, unlike other classes of nanoparticles, they can also undergo a multiphoton process (known as upconversion) where the NIR excitation light is converted to higher energies resulting in anti-Stokes luminescence spanning the UV-visible-NIR regions. Perhaps the biggest impact of such materials would be in the field of disease diagnostics and therapeutics, now commonly referred to as theranostics. Due to the versatility of their optical properties, it now becomes possible to generate high-energy light (UV or blue) in situ to trigger other light activated therapeutic modalities (i.e. drug release) while using the NIR emission for diagnostics (i.e. bioimaging, nanothermometry). Here, we present the synthesis of various NIR excited (and emitting) rare earth doped core/shell (and multishell) nanoparticles and demonstrate how their luminescence properties can be exploited for potential use in diverse biomedical applications.

Decoupled Rare-Earth Nanoparticles for On-Demand Upconversion Photodynamic Therapy and High-Contrast Near Infrared Imaging in NIR IIb.

Rare-earth doped multi-shell nanoparticles slated for theranostic applications produce a variety of emission bands upon near-infrared (NIR) excitation. Their downshifting emission is useful for high-contrast NIR imaging, while the upconversion light can induce photodynamic therapy (PDT). Unfortunately, integration of imaging and therapy is challenging. These modalities are better to be controlled independently so that, with the help of imaging, selective delivery of a theranostic agent at the site of interest could be ensured prior to on-demand PDT initiation. We introduce here multi-shell rare-earth doped nanoparticles (RENPs) arranged in a manner to produce only downshifting emission for NIR imaging when excited at one NIR wavelength and upconversion emission for therapeutic action by using a different excitation wavelength. In this work, multi-shell RENPs with a surface-bound sensitizer have been synthesized for decoupled 1550 nm downshifting emission upon 800 nm excitation and 550 nm upconversion emission caused by 980 nm irradiation. The independently controlled emission bands allow for high-contrast NIR imaging in NIR-IIb of optical transparency that gives high-contrast images due to significantly reduced light scattering. This can be conducted prior to PDT using 980 nm to produce upconverted light at 550 nm that excites the RENP surface-bound photosensitizer, Rose Bengal (RB), to effect photodynamic therapy with high specificity and safer theranostics.

(Invited) Multi-Architectured Lanthanide Doped Nanoparticles for Theranostics

Light triggered theranostic (therapy and diagnostic) nanoplatforms have gained a considerable attention in recent years. In theranostics, light as an external trigger stands out due to its non-invasiveness, high local precision and temporal resolution. Many such nanoplatforms employ high-energy (visible or UV) light to initiate the individual therapeutic and diagnostic modalities. However, light at these wavelengths suffers from inherent drawbacks such as having little to no penetration in living tissue, inducing autofluorescence from inherent fluorophores or chromophores in tissues and causing photodamage. The use of near-infrared (NIR) light for excitation mitigates such drawbacks associated with high-energy excitation, for example, little to no background autofluorescence from the specimen under investigation as well as no incurred photodamage. Moreover, one of the biggest limitations is that of penetration and NIR light can penetrate tissues much better than high-energy light especially when these wavelengths lie within the three biological windows where tissues are optically transparent. At the forefront of NIR excited nanomaterials are lanthanide doped nanoparticles, which can undergo conventional (Stokes) luminescence and emit in the NIR biological windows. However, unlike other classes of nanoparticles, they can also undergo a multiphoton excitation process where the NIR excitation light is converted to higher energies resulting in anti-Stokes luminescence spanning the UV-visible-NIR regions (known as upconversion). Thus, it now becomes possible to generate upconverted high-energy light (UV or visible) in situ to trigger other light activated therapeutic modalities (i.e. drug release) while using the NIR emission for diagnostics (i.e. bioimaging, nanothermometry). Here, we demonstrate how the luminescence properties (upconversion and NIR) of various lanthanide doped core/shell (and multishell) nanoparticles can be exploited for potential use in theranostics.

Routes for Metallization of Perovskite Solar Cells.

The application of metallic nanoparticles leads to an increase in the efficiency of solar cells due to the plasmonic effect. We explore various scenarios of the related mechanism in the case of metallized perovskite solar cells, which operate as hybrid chemical cells without p-n junctions, in contrast to conventional cells such as Si, CIGS or thin-layer semiconductor cells. The role of metallic nano-components in perovskite cells is different than in the case of p-n junction solar cells and, in addition, the large forbidden gap and a large effective masses of carriers in the perovskite require different parameters for the metallic nanoparticles than those used in p-n junction cells in order to obtain the increase in efficiency. We discuss the possibility of activating the very poor optical plasmonic photovoltaic effect in perovskite cells via a change in the chemical composition of the perovskite and through special tailoring of metallic admixtures. Here we show that it is possible to increase the absorption of photons (optical plasmonic effect) and simultaneously to decrease the binding energy of excitons (related to the inner electrical plasmonic effect, which is dominant in perovskite cells) in appropriately designed perovskite structures with multishell elongated metallic nanoparticles to achieve an increase in efficiency by means of metallization, which is not accessible in conventional p-n junction cells. We discuss different methods for the metallization of perovskite cells against the background of a review of various attempts to surpass the Shockley–Queisser limit for solar cell efficiency, especially in the case of the perovskite cell family.

Preclinical Testing of Dendritic Core-Multishell Nanoparticles in Inflammatory Skin Equivalents.

Human skin equivalents emerged as novel tools in preclinical dermatological research. It is being claimed that they may bridge the translational gap between preclinical and clinical research, yet only a few studies have investigated their suitability for preclinical drug testing so far. Therefore, we investigated if inflammatory skin equivalents, which emulate hallmarks of atopic dermatitis (AD), are suitable to assess the anti-inflammatory effects of dexamethasone (DXM) in a cream formulation or loaded onto dendritic core-multishell nanoparticles. Topical DXM application resulted in significantly decreased expression of the proinflammatory cytokine TSLP, increased expression of the skin barrier protein involucrin, and facilitated glucocorticoid receptor translocation in a dose-dependent manner. Further, DXM treatment inhibited gene expression of extracellular matrix components, potentially indicative of the known skin atrophy-inducing side effects of glucocorticoids. Overall, we were able to successfully assess the anti-inflammatory effects of DXM and the superiority of the nanoparticle formulation. Nevertheless the identification of robust readout parameters proved challenging and requires careful study design.

Reproducible Single-Droplet multiplexed detection through Excitation-Encoded Tri-mode upconversion solid sensors

The article reports a reproducible and resuable sensor for upconversion fluorescence multiplexed detection constructed by excitation-encoded core-multishell upconversion nanoparticles with a thin superhydrophobic SiO 2 layer, which outperforms the sensors with co-doped upconversion nanoparticles and multi-channel upconversion nanoparticle mixtures. Such solid-multi-mode sensor can achieve visual colorimetric and reproducible multiplexed simultaneous detection of multi-analytes. Upconversion multiplexed optical sensors are promising in clinical diagnostics, molecular mapping and environmental monitoring. However, traditional co-doped emitter sensors and mixture sensors show poor sensitivity and reproducibility due to the strong cross-relaxation quenching and instability. Herein, upconversion multi-shell nanoparticles are, for the first time, applied as excitation-controlled nanosensors for reproducible and channel-independent multiplexed detection. The multi-shell structure favors the excitation-encoded reproducible blue/green/red fluorescence signals from different upconversion shells in a single upconversion nanosensor, avoiding using instable upconversion nanoparticle mixtures for multiplexed detection. A reproducible and self-cleaning solid tri-mode sensor is constructed by the upconversion multi-shell nanoparticles coated with a thin superhydrophobic SiO 2 layer. The solid sensor shows superior single-droplet (≈10 µL) multiplexed detection capability with a low detection limit for dye molecules (∼0.1 μg/mL), high stability and excellent recyclability (more than 100 cycles). This work provides an intriguing strategy to achieve channel-independent, reproducible UC multiplexed sensors for simultaneous detection of multi-analytes.

Multishell Nanoparticles with "Linkage Mechanism" for Thermal Responsive Photodynamic and Gas Synergistic Therapy.

The strategies of combining photodynamic therapy (PDT) with other therapeutics are considered to be the most suitable methods in improving the antitumor therapeutic efficiency. Herein, a "Linkage Mechanism" strategy based on thermal controllable multishell nanoparticles (CuS@SiO2 -l-Arg (l-arginine)@PCM (phase-change material)-Ce6 (chiorin e6)) is proposed for combing PDT and NO-based gas therapy. Upon 1060nm laser irradiation, the PCMs will melt under the photothermal effect induced by CuS and the loaded Ce6 and l-Arg can accurately release from the nanoparticles. Under further 660nm laser irradiation, the released Ce6 will produce plenty of singlet oxygen (1 O2 ) for PDT, while the generated 1 O2 can oxidize l-Arg to release NO for the synergy of PDT and gas therapy. The "Linkage Mechanism" can achieve precise release of the payloads under the control of photothermal effect at tumor site, and the chain reaction of PDT and gas therapy overcomes the problem of premature release of gas during transportation. Benefiting from the guidance of fluorescence imaging and second near infrared photoacoustic imaging by Ce6 and CuS, both in vitro and in vivo experiments present effective antitumor efficiencies. The nanoparticles provide new ideas for controllable release of drugs and the synergistic effect of multiple treatments, possessing great application prospects.

Dual magnetic field and temperature optical probes of controlled crystalline phases in lanthanide-doped multi-shell nanoparticles.

The engineering of core@multi-shell nanoparticles containing heterogeneous crystalline phases in different layers constitutes an important strategy for obtaining optical probes. The possibility of obtaining an opto-magnetic core@multi-shell nanoparticle capable of emitting in the visible and near-infrared ranges by upconversion and downshifting processes is highly desirable, especially when its optical responses are dependent on temperature and magnetic field variations. This work proposes the synthesis of hierarchically structured core@multi-shell nanoparticles of heterogeneous crystalline phases: a cubic core containing DyIII ions responsible for magnetic properties and optically active hexagonal shells, where ErIII, YbIII, and NdIII ions were distributed. This system shows at least three excitation energies located at different biological windows, and its emission intensities are sensitive to temperature and external magnetic field variations. The selected crystalline phases of the core@multi-shell nanoparticles obtained in this work is fundamental to the development of multifunctional materials with potential applications as temperature and magnetic field optical probes.

Unraveling Complexity: A Strategy for the Characterization of Anisotropic Core Multishell Nanoparticles

AbstractIn this work, a widely applicable routine to characterize the core, surface, stability, and optical properties of CdSe/CdS/ZnS core–shell–shell nanorods after multiple growth steps is established. First, size, shape, and shell thickness of the nanorods are characterized by transmission electron microscopy (TEM), analytical ultracentrifugation (AUC), and small angle X‐ray/neutron scattering (SAXS/SANS). In the next step, Fourier‐transform infrared (FT‐IR) spectroscopy, thermogravimetric analysis (TGA), and SANS measurements are applied to determine the surface species of nanorods. Then, the colloidal stability of the nanorods is investigated by UV–vis spectroscopy and dynamic light scattering (DLS) after different washing cycles. Finally, photoluminescence quantum yield (PLQY) of the nanorods during washing and sample storage is determined. With this highly complementary routine for particle characterization, the core, surface, stability, and optical properties of nanorods after multiple growth steps are resolved. The results demonstrate the importance of the developed toolbox to characterize such highly complex, anisotropic nanorods for a technical environment. This is of major importance for the handling of colloidal quantum materials and their quality control in industrial applications.

Green and Facile Fabrication of α-Zirconium Phosphate-Based Core–Multishell Nanoparticles for Enhancing Fire Retardant Performance of Poly(vinyl alcohol)

At present, most flame retardants, especially halogenated compounds, are banned because of concern for environmental and health issues. In prospect of developing more ecofriendly and effective flam...

Hybridization of plasmon modes in multishell bimetallic nanoparticles: a numerical study

We study the near-infrared properties of spherical multishell nanoparticles comprising a loss-less dielectric core enclosed by a concentric layering of metallic–dielectric–metallic nanoshells. The coupling between the metallic shells induces plasmon resonance redshifts and peak splitting in the absorption spectra of the layered particle relative those of the metallic constituents. We use full-wave electromagnetic analysis to investigate changes in the absorption spectra as a function of key parameters including the material properties of the inner and outer metallic shells and the aspect ratio of their inner and outer radii. We systematically vary the aspect ratios and quantify the degree of plasmonic coupling between the metallic nanoshells. Our analysis reveals conditions under which the spectral resonance peaks blueshift and/or redshift. We consider bimetallic particles with gold and silver nanoshells and determine the dependency of plasmon resonance peak shifting and splitting as a function of the order of these material layers, i.e., as inner or outer shells.

Activatable Photodynamic Therapy with Therapeutic Effect Prediction Based on a Self-correction Upconversion Nanoprobe.

Though emerging as a promising therapeutic approach for cancers, the crucial challenge for photodynamic therapy (PDT) is activatable phototoxicity for selective cancer cell destruction with low "off-target" damage and simultaneous therapeutic effect prediction. Here, we design an upconversion nanoprobe for intracellular cathepsin B (CaB)-responsive PDT with in situ self-corrected therapeutic effect prediction. The upconversion nanoprobe is composed of multishelled upconversion nanoparticles (UCNPs) NaYF4:Gd@NaYF4:Er,Yb@NaYF4:Nd,Yb, which covalently modified with an antenna molecule 800CW for UCNPs luminance enhancement under NIR irradiation, photosensitizer Rose Bengal (RB) for PDT, Cy3 for therapeutic effect prediction, and CaB substrate peptide labeled with a QSY7 quencher. The energy of UCNPs emission at 540 nm is transferred to Cy3/RB and eventually quenched by QSY7 via two continuous luminance resonance energy transfer processes from interior UCNPs to its surface-extended QSY7. The intracellular CaB specifically cleaves peptide to release QSY7, which correspondingly activates RB with reactive oxygen species (ROS) generation for PDT and recovers Cy3 luminance for CaB imaging. UCNPs emission at 540 nm remains unchanged during the peptide cleavage process, which is served as an internal standard for Cy3 luminance correction, and the fluorescence intensity ratio of Cy3 over UCNPs (FI583/FI540) is measured for self-corrected therapeutic effect prediction. The proposed self-corrected upconversion nanoprobe implies significant potential in precise tumor therapy.

Multi-shelled upconversion nanostructures with enhanced photoluminescence intensity via successive epitaxial layer-by-layer formation (SELF) strategy for high-level anticounterfeiting

Multi-shelled upconversion nanoparticles with significantly enhanced emission intensity are synthesized via successive epitaxial layer-by-layer formation (SELF) strategy and used in dual-modal anticounterfeiting and latent fingerprint detection.

Resonant Coupling and Gain Singularities in Metal/Dielectric Multishells: Quasi-Static Versus T-Matrix Calculations

We investigate the resonant gain response in doped multishell hybrid nanoparticles made of concentric and alternated doped dielectric and metal shells. In particular, we compare the enhanced extinction properties calculated in a quasi-static approximation with accurate light scattering calculations in the T-matrix formalism. We show that, even for small hybrid particles, a difference in the calculated optoplasmonic mode yields a dramatic change in the resonant coupling with the doped molecular system. Thus, although a simple dipole approach gives a fast qualitative view of the multishell gain-assisted response, a complete light scattering framework is crucial for a quantitative investigation of these hybrid nanosystems.