Mesoporous silica encapsulating upconversion luminescence rare-earth fluoride nanorods for secondary excitation

Mesoporous Silica-Coated Upconverting Nanorods for Singlet Oxygen Generation: Synthesis and Performance

Photodynamic therapy (PDT) has been reported as a possible pathway for the treatment of tumors. The exploration for promising PDT systems thus attracts continuous research efforts. This work focused on an ordered core–shell structure encapsulated by mesoporous SiO₂ with the upconverting emission property following a surfactant-assisted sol–gel technique. The mesoporous silica shell possessed a high surface area-to-volume ratio and uniform distribution in pore size, favoring photosensitizer (rose bengal) loading. Simultaneously, upconverting nanocrystals were synthesized and used as the core. After modification via hydrophobic silica, the hydrophobic upconverting nanocrystals became hydrophilic ones. Under near-infrared (NIR) light irradiation, the nanomaterials exhibited strong green upconverting luminescence so that rose bengal could be excited to produce singlet oxygen. The photodynamic therapy (PDT) feature was evaluated using a ¹O₂ fluorescent indicator. It was found that this core–shell structure generates ¹O₂ efficiently. The novelty of this core–shell structure was the combination of upconverting nanocrystals with a mesoporous SiO₂ shell so that photosensitizer rose bengal could be effectively adsorbed in the SiO₂ shell and then excited by the upconverting core.

Clinical therapies and nano drug delivery systems for urinary bladder cancer

Bladder cancer is the 10^th most commonly occurring malignancy worldwide with a 75% of 5-year survival rate, while it ranks 13^th among the deaths occurring due to cancer. The majority of bladder cancer cases are diagnosed at an early stage and 70% are of non-invasive grade. However, 70% of these cases develop chemoresistance and progress to the muscle invasive stage. Conventional chemotherapy treatments are unsuccessful in curbing chemoresistance, bladder cancer progression while having an adverse side effect, which is mainly due to off-target drug distribution. Therefore, new drug delivery strategies, new therapeutics and therapies or their combination are being explored to develop better treatments. In this regard, nanotechnology has shown promise in the targeted delivery of therapeutics to bladder cancer cells. This review discusses the recent discovery of new therapeutics (chemotherapeutics, immunotherapeutic, and gene therapies), recent developments in the delivery of therapeutics using nano drug delivery systems, and the combination treatments with FDA-approved therapies, i.e., hyperthermia and photodynamic therapy. We also discussed the potential of other novel drug delivery systems that are minimally explored in bladder cancer. Lastly, we discussed the clinical status of therapeutics and therapies for bladder cancer. Overall, this review can provide a summary of available treatments for bladder cancer, and also provide opportunities for further development of drug delivery systems for better management of bladder cancer.

Effect of Cationic Brush-Type Copolymers on the Colloidal Stability of GdPO4 Particles with Different Morphologies in Biological Aqueous Media

In this study, we present the synthesis of cationic brush-type polyelectrolytes and their use in the stabilization of GdPO4 particles in aqueous media. Polymers of various compositions were synthesized via the RAFT polymerization route. SEC equipped with triple detection (RI, DP, RALS, and LALS) was used to determine the molecular parameters (Mn, Mw, Mw/Mn). The exact composition of synthesized polymers was determined using NMR spectroscopy. Cationic brush-type polymers were used to improve the stability of aqueous GdPO4 particle dispersions. First, the IEPs of GdPO4 particles with different morphologies (nanorods, hexagonal nanoprisms, and submicrospheres) were determined by measuring the zeta potential of bare particle dispersions at various pH values. Afterward, cationic brush-type polyelectrolytes with different compositions were used for the surface modification of GdPO4 particles (negatively charged in alkaline media under a pH value of ∼10.6). The concentration and composition effects of used polymers on the change in particle surface potential and stability (DLS measurements) in dispersions were investigated and presented in this work. The most remarkable result of this study is redispersible GdPO4 nanoparticle colloids with increased biocompatibility and stability as well as new insights into possible cationic brush-type polyelectrolyte applicability in both scientific and commercial fields.

Optically active neodymium hydroxide surface-functionalized mesoporous silica micro-cocoons for biomedical applications

Neodymium hydroxide (Nd(OH)₃)-surface modified mesoporous silica micro-cocoon microstructures were prepared using a facile single-step sol-gel chemical process. XRD revealed the semi-crystalline nature of the as-prepared materials. TEM and SEM micrographs exhibited highly monodisperse, non-aggregated, typical ordered mesoporous, and irregular sized cocoon-shaped micro-structures with a narrow size distribution. Optical properties, that were examined in the aqueous media, revealed a high colloidal stability and the formation of a semi-transparent colloidal solution. The colloidal solution of Nd(OH)₃-surface functionalized micro-structures revealed well characteristics absorption bands of Nd³⁺ ions in the visible region. thus validating the successful coating of SiO₂@Nd(OH)₃ layer over the surface silica forming core-shell structures. Zeta potential, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) bromide, and neutral red uptake assays were applied in a dose-dependent manner to investigate the biocompatibility and toxic potential of the designed cocoon-shaped microstructures. Both the assays and the high zeta potential value demonstrated good cell viability even at high concentrations and hydrophilic conditions, indicating excellent biocompatibility and non-toxicity. These highly hydrophilic, optically active, mesoporous, biocompatible, and non-toxic cocoon-shaped microstructures could be potentially suitable candidates for optical bio-probes and drug delivery applications.

β-NaYF4:Yb,Er,Gd nanorods@1T/2H-MoS2 for 980 nm NIR-triggered photocatalytic bactericidal properties

Fabrication of β-NaYF₄:Yb,Er,Gd@1T/2H-MoS₂ nanocomposites for NIR-driven photocatalytic sterilization of Escherichia coli.

Facile Incorporation of "Aggregation-Induced Emission"-Active Conjugated Polymer into Mesoporous Silica Hollow Nanospheres: Synthesis, Characterization, Photophysical Studies, and Application in Bioimaging

Typical aggregation-induced emission (AIE) luminogens tetraphenylethylene (TPE) and triphenylamine have been used to construct an AIE-active conjugated polymer, namely, poly(N,N-diphenyl-4-(4-(1,2,2-triphenylvinyl)styryl)aniline) (PTPA), which consist of D-π-A architecture by Wittig polymerization. We fabricated mesoporous silica hollow nanospheres (MSHNs) which were encapsulated with the AIE-active polymer for applications in cellular imaging. It exhibits a positive solvatochromism effect by increasing solvent polarity, supported by theoretical calculation using density functional theory. The structure of the monomers and polymer was confirmed by Fourier transform infrared, nuclear magnetic resonance, and high-resolution mass spectrometry techniques. Considering the advantage of high brightness in the fluorescence of PTPA, it was encapsulated into MSHNs by a noncovalent approach, and the surface was functionalized with an anti-EpCAM (antiepithelial cell adhesion molecule) aptamer through conjugation with γ-glycidoxypropyltrimethoxysilane for targeting cancer cells specifically. The aptamer-functionalized Apt-MSHNs exhibited excellent biocompatibility with the liver cancer-Huh-7 cells used for this study and was efficiently internalized by these cells. Because EpCAM are overexpressed in multiple carcinomas, including liver cancer, these aptamer-conjugated AIE MSHNs are therefore good candidates for targeted cellular imaging applications.

Aqueous dispersible green luminescent yttrium oxide:terbium microspheres with nanosilica shell coating

Tb-doped Y₂O₃ microspheres (MSs) were prepared via a homogeneous thermal degradation process at a low temperature and then coated with a nanosilica shell (Y₂O₃:Tb@SiO₂) using a sol-gel process. The core MSs were highly crystalline and spherical with a porous surface, single cubic phase, and particle size of 100-250 nm. Transmission electron microscopy (TEM) images clearly showed the spherical shape of the as-prepared core MSs, which were fully covered with a thick and mesoporous nanosilica shell. Fourier transform infrared (FTIR) spectra displayed the well-resolved infrared absorption peaks of silica (SiO, SiOSi, etc.), confirming the presence of the silica surface coating. The core MSs retained their spherical shape even after heat treatment and subsequent silica surface coating. It was observed that the core/shell MSs are easily dispersible in aqueous media and form a semi-transparent colloidal solution. Ultraviolet/visible and zeta potential studies were tested to prove the changes in the surface chemistry of the as-designed core/shell MSs and compare with their core counterpart. The growth of the amorphous silica shell not only increased the particle size but also enhanced remarkably the solubility and colloidal stability of the MSs in aqueous media. The strongest emission lines originating from the characteristic intra-shell 4f-4f electronic transitions of Tb ions were quenched after silica layer deposition, but the MSs still showed strong green (⁵D₄ → ⁷F₅ at 530-560 nm as most dominant) emission efficiency, which indicates great potential in fluorescent bio-probes. The emission intensity is discussed in relation to the quenching mechanism induced by surface silanol (Si-OH) groups, particle size, and surface charge.

Synthesis and characterization of macroporous europium-doped Ca12Al14O33 (C12A7:Eu3+) and its application in metal ion detection

Macroporous europium-doped Ca₁₂Al₁₄O₃₃ (C12A7:Eu³⁺) was prepared via a sol–gel method followed by heat-treatment, and the resultant macroporous C12A7:Eu³⁺ shows potential for practical application in metal ion detection and has a good response to Pb²⁺ ions.

Resonance Energy Transfer in Upconversion Nanoplatforms for Selective Biodetection

Resonance energy transfer (RET) describes the process that energy is transferred from an excited donor to an acceptor molecule, leading to a reduction in the fluorescence emission intensity of the donor and an increase in that of the acceptor. By this technique, measurements with the good sensitivity can be made about distance within 1 to 10 nm under physiological conditions. For this reason, the RET technique has been widely used in polymer science, biochemistry, and structural biology. Recently, a number of RET systems incorporated with nanoparticles, such as quantum dots, gold nanoparticles, and upconversion nanoparticles, have been developed. These nanocrystals retain their optical superiority and can act as either a donor or a quencher, thereby enhancing the performance of RET systems and providing more opportunities in excitation wavelength selection. Notably, lanthanide-doped upconversion nanophosphors (UCNPs) have attracted considerable attention due to their inherent advantages of large anti-Stoke shifts, long luminescence lifetimes, and absence of autofluorescence under low energy near-infrared (NIR) light excitation. These nanoparticles are promising for the biodetection of various types of analytes. Undoubtedly, the developments of those applications usually rely on resonance energy transfer, which could be regarded as a flexible technology to mediate energy transfer from upconversion phosphor to acceptor for the design of luminescent functional nanoplatforms. Currently, researchers have developed many RET-based upconversion nanosystems (RET-UCNP) that respond to specific changes in the biological environments. Specifically, small organic molecules, biological molecules, metal-organic complexes, or inorganic nanoparticles were carefully selected and bound to the surface of upconversion nanoparticles for the preparation of RET-UCNP nanosystems. Benefiting from the advantage and versatility offered by this technology, the research of RET-based upconversion nanomaterials should have significant implications for advanced biomedical applications. It should be noted that energy transfer in a UCNP based nanosystem is most often related to resonance energy transfer but that reabsorption (and maybe other energy transfer processes) may also play an important role and that more studies regarding the fundamental aspects for energy transfer with UCNPs is necessary. In this Account, we present an overview of recent advances in RET-based upconversion nanocomposites for biodetection with a particular focus on our own work. We have designed a series of upconversion nanoplatforms with remarkably high versatility for different applications. The experience gained from our strategic design and experimental investigations will allow for the construction of next-generation luminescent nanoplatform with marked improvements in their performance. The key aspects of this Account include fundamental principles, design and preparation strategies, biodetection in vitro and in vivo, future opportunities, and challenges of RET-UCNP nanosystems.

Hexagonal β-Na(Y,Yb)F4 based core/shell nanorods: epitaxial growth, enhanced and tailored up-conversion emission

Rare earth ions-doped hexagonal β-Na(Y,Yb)F₄ nanorods can be coated perfectly with either optically active or inert shells to improve and/or tailor the upconversion emission through a one-step epitaxial growth method from α-phased nanoparticles.

High efficiency upconversion nanophosphors for high-contrast bioimaging

Upconversion nanoparticles (UCNPs) are of interest because they allow suppression of tissue autofluorescence and are therefore visible deep inside biological tissue. Compared to upconversion dyes, UCNPs have a lower pump intensity threshold, better photostability, and less toxicity. Recently, YVO₄: Er⁺³, Yb⁺³ nanoparticles were shown to exhibit strong up-conversion luminescence with a relatively low 10 kW cm^-2 excitation intensity even in water, which makes them excellent bio-imaging candidates. Herein, we investigate their use as internal probes in insects by injecting YVO₄ : Er⁺³, Yb⁺³ nanoparticles into fire ants as a biological model, and obtain 2D optical images with 980 nm illumination. High-contrast images with high signal-to-noise ratio are observed by detecting the up-conversion fluorescence as the excitation laser is scanned.

Ru(bpy)2(phen-5-NH2)2+ doped ultrabright and photostable fluorescent silica nanoparticles

Ru(bpy)₂(phen-5-NH₂)²⁺ doped silica nanoparticles with high fluorescence brightness and controllable size are synthesized via reverse microemulsion method by introducing ethanol to reaction system.

Near-infrared light-controlled drug release and cancer therapy with polymer-caged upconversion nanoparticles

The core–shell nanocarrier, based on spiropyran-containing copolymer coated upconversion nanocomposites, was successfully prepared via a facile self-assembly process for NIR-triggered drug release and cancer therapy.

Lab on upconversion nanoparticles: optical properties and applications engineering via designed nanostructure

This review aims to summarize recent progress in optical properties and applications engineering of upconversion nanoparticles via the designed nanostructure.

Hydrothermal synthesis and magnetic behaviour of beta-Li3VF6 and Na3VF6

Fluorides Li₃VF₆ and Na₃VF₆ were synthesized without using harmful and corrosive HF acid.

Mesoporous silica-coated plasmonic nanostructures for surface-enhanced Raman scattering detection and photothermal therapy

The design and fabrication of core-shell and yolk-shell nanostructures with surface plasmon resonance (SPR)-active center protected by permeable mesoporous channels can raise the new vitality into the catalysis and biological applications. Hybrid plasmonic-mesoporous silica nanocarriers consisting of Ag and Au-Ag alloy nanoparticles are fabricated through spatially confined galvanic replacement approach. The plasmonic absorption peaks can be finely controlled to the near-infrared (NIR) region (500-790 nm) that is beneficial for tissue transmittance. The mesoporous silica shell facilitates also protection of Au-Ag cores and affords the channels between the exterior and interior capsule environments, thereby endowing the multiple applications. In the present work, it is successfully demonstrated that mesoporous silica-coated Au-Ag alloy core-shell and yolk-shell nanocarriers can serve as good substrates for surface-enhanced Raman scattering (SERS) detection. The SERS signal intensities of nanocarriers are highly dependent on the SPR peaks and the contents of gold. Simultaneously, the synthesized Au-Ag@mSiO2 nanocarriers with SPR peak at ≈790 nm can be applied in NIR-sensitive SERS detection and photothermal therapy.

Current advances in precious metal core-shell catalyst design

Precious metal nanoparticles are commonly used as the main active components of various catalysts. Given their high cost, limited quantity, and easy loss of catalytic activity under severe conditions, precious metals should be used in catalysts at low volumes and be protected from damaging environments. Accordingly, reducing the amount of precious metals without compromising their catalytic performance is difficult, particularly under challenging conditions. As multifunctional materials, core-shell nanoparticles are highly important owing to their wide range of applications in chemistry, physics, biology, and environmental areas. Compared with their single-component counterparts and other composites, core-shell nanoparticles offer a new active interface and a potential synergistic effect between the core and shell, making these materials highly attractive in catalytic application. On one hand, when a precious metal is used as the shell material, the catalytic activity can be greatly improved because of the increased surface area and the closed interfacial interaction between the core and the shell. On the other hand, when a precious metal is applied as the core material, the catalytic stability can be remarkably improved because of the protection conferred by the shell material. Therefore, a reasonable design of the core-shell catalyst for target applications must be developed. We summarize the latest advances in the fabrications, properties, and applications of core-shell nanoparticles in this paper. The current research trends of these core-shell catalysts are also highlighted.

Nonionic fluorosurfactant as an ideal candidate for one-step modification of gold nanorods

In this work, a novel protocol was developed for size tuning and cetyltrimethylammonium bromide (CTAB) removal of gold nanorods using commercially available nonionic fluorosurfactants (FSN), an excellent candidate for PEG and other modification reagents. The tunable gold nanorods can easily be obtained by stopping the ligand replacement reaction at different time intervals. The FSN-coated gold nanorods are stable in the presence of high salt concentrations and over a wide range of pH values. Additionally, the cellular uptake experiments demonstrate that the FSN-coated gold nanorods have superior features in comparison to the widely used PEG-coated gold nanorods, such as high uptake amount, tunable uptake and excellent stability. Our findings suggest that FSN ligands are an ideal candidate for modifying gold nanorods with tunable aspect ratios, excellent biocompatibility, nontoxicity, and high stability, enabling conjugation to biomolecules for specific targeting, uptake, and delivery.

Advances in noninvasive functional imaging of bone

The demand for functional imaging in clinical medicine is comprehensive. Although the gold standard for the functional imaging of human bones in clinical settings is still radionuclide-based imaging modalities, nonionizing noninvasive imaging technology in small animals has greatly advanced in recent decades, especially the diffuse optical imaging to which Britton Chance made tremendous contributions. The evolution of imaging probes, instruments, and computation has facilitated exploration in the complicated biomedical research field by allowing longitudinal observation of molecular events in live cells and animals. These research-imaging tools are being used for clinical applications in various specialties, such as oncology, neuroscience, and dermatology. The Bone, a deeply located mineralized tissue, presents a challenge for noninvasive functional imaging in humans. Using nanoparticles (NP) with multiple favorable properties as bioimaging probes has provided orthopedics an opportunity to benefit from these noninvasive bone-imaging techniques. This review highlights the historical evolution of radionuclide-based imaging, computed tomography, positron emission tomography, and magnetic resonance imaging, diffuse optics-enabled in vivo technologies, vibrational spectroscopic imaging, and a greater potential for using NPs for biomedical imaging.

A simple and efficient synthetic route for preparation of NaYF4 upconversion nanoparticles by thermo-decomposition of rare-earth oleates

A two-step synthetic route for fabrication of hexagonal-phase NaYF₄ and NaYF₄-based nano-phosphors based on thermal decomposition of their corresponding oleate precursors is provided and systematically investigated.

Regulation of multifunctional mesoporous core–shell nanoparticles with luminescence and magnetic properties for biomedical applications

A new kind of Gd³⁺-based/mesoporous silica-coated multifunctional nanomedical platform is developed for potential use as optical-MR dual-modal imaging agent.

Orthorhombic KSc2F7:Yb/Er nanorods: controlled synthesis and strong red upconversion emission

For the first time, we have synthesized orthorhombic phase KSc2F7:20%Yb/2%Er (KSc2F7:Yb/Er) nanorods and further studied the crystal structure and morphology evolution, as well as their upconversion (UC) properties under varying F(-) contents and reaction temperatures. Different from β-NaYF4:20%Yb/2%Er (NaYF4:Yb/Er) nanorods that usually give strong green UC luminescence, strong red UC emission was observed in KSc2F7:Yb/Er nanorods under 980 nm laser excitation. Their UC mechanisms are further analyzed and compared. This study provides a novel type of rare earth nanorods with strong red UC emissions which have great potential in high resolution 3-dimensional bioimaging, color displays, solid-state lasers, and photocatalysis.

Recent advances in lanthanide-doped upconversion nanomaterials: synthesis, nanostructures and surface modification

Owing to their unique photo-physical properties, rare-earth ions-doped upconversion nanoparticles (UCNPs) have attracted extensive attention in recent years. UCNPs have many special merits, such as a long luminescence lifetime, narrow emission band widths, high quantum yields and low toxicity, which allows their potential applications in bio-medical field, biological luminescent labels and drug delivery carriers. Compared with traditional fluorescence labels exited by UV (ultraviolet), such as organic dyes and quantum dots, UCNPs can transfer near-infrared (NIR) light into visible light, which is commonly called upconversion luminescence (UCL). This paper reviews the recent advances of several typical synthesis methods of UCNPs in detail as well as the fabrication and optimization of the particle morphology, and the latest advances of UCNPs for multimode imaging, surface passivation and functionalization are also described.

Electrospun upconversion composite fibers as dual drugs delivery system with individual release properties

Novel multifunctional poly(ε-caprolactone)-gelatin encapsulating upconversion core/shell silica nanoparticles (NPs) composite fibers as dual drugs delivery system (DDDS), with indomethacin (IMC) and doxorubicin (DOX) releasing in individual release properties, have been designed and fabricated via electrospinning process. Uniform and monodisperse upconversion (UC) luminescent NaYF4:Yb(3+), Er(3+) nanocrystals (UCNCs) were encapsulated with mesoporous silica shells, resulting in the formation of core/shell structured NaYF4:Yb(3+), Er(3+)@mSiO2 (UCNCs@mSiO2) NPs, which can be performed as DOX delivery carriers. These UCNCs@mSiO2 NPs loading DOX then were dispersed into the mixture of poly(ε-caprolactone) (PCL) and gelatin-based electrospinning solution containing IMC, followed by the preparation of dual drug-loaded composite fibers (DDDS) via electrospinning method. The drugs release profiles of the DDDS were measured, and the results indicated that the IMC and DOX released from the electrospun composite fibers showed distinct properties. The IMC in the composite fibers presented a fast release manner, while DOX showed a sustained release behavior. Moreover, the UC luminescent intensity ratios of (2)H(11/2)/(4)S(3/2)-(4)I(15/2) to (4)F(9/2)-(4)I(15/2) from Er(3+) vary with the amounts of DOX in the system, and thus drug release can be tracked and monitored by the luminescence resonance energy transfer (LRET) mechanism.

Multiwalled carbon nanotubes and NaYF4:Yb3+/Er3+ nanoparticle-doped bilayer hydrogel for concurrent NIR-triggered drug release and up-conversion luminescence tagging

Bilayer thermosensitive P(NIPAm-co-AAm) hydrogel discs were prepared by a facile UV light initiation process from N-isopropylacrylamide (NIPAm) and acrylamide (AAm) monomers' cross-linking copolymerization. Poly(ethylene glycol) (PEG) as a pore-forming agent was added in order to form a porous structure and improve the water content in the hydrogel. Functional materials of NaYF4:Yb(3+)/Er(3+) nanoparticles and multiwalled carbon nanotubes (MWCNTs) were incorporated into different layers of the P(NIPAm-co-AAm) hydrogel for the purpose of up-conversion luminescence labeling and the NIR light antenna effect, respectively. Significantly improved drug release from composite hydrogels was achieved in response to 980 nm NIR light irradiation by using lysozyme as a macromolecular drug. The multifunctional hydrogel reported here provides a platform for simultaneous NIR luminescence labeling and NIR-driven drug release.

An optical probe possessing upconversion luminescence and Hg(2+)-sensing properties

A Hg(2+)-selective chromophoric upconversion nanosystem is achieved by covalently grafting Rhodamine B hydrazide (RB-hydrazide) onto upconversion luminescent nanorod core-shell structures. The prepared β-NaYF4 nanorods are coated with silica and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX), Fourier-transform infrared spectroscopy (FTIR), and photoluminescence spectra. Under 980 nm excitation, the upconversion luminescence is sensitive towards Hg(2+) because RB-hydrazide-Hg can efficiently absorb green upconversion emission. The prepared nanocomposites exhibit high sensitivity and selectivity towards Hg(2+) over other metal ions. These results indicate that this nanosystem could be developed as a promising fluorescence probe for detecting Hg(2+) ions.

Facile synthesis of water-soluble luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres

Luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres were synthesized through W/O microemulsion process at ambient temperature. The negatively charged silica favors a coating of the positively charged Tb3+ composite. Thus, silicon layer was adsorbed on the surface of Tb(OH)3 groups to form Tb-O-Si through electrostatic interaction. X-ray diffraction, field emission transmission electron microscopy (FE-TEM), energy-dispersive X-ray spectrometry, and Fourier transform infrared, UV/Visible, and photoluminescence spectroscopies were applied to examine the phase purity, crystallinity, surface morphology, and optical properties of the core-shell nanospheres. The FE-TEM results have revealed typically ordered mesoporous characteristics of the material with monodisperse spherical morphology in a narrow size distribution. The luminescent mesoporous core-shell nanospheres exposed remarkable splitting with broadening in the emission transition 5D4 → 7F5 (543 nm). In addition, the luminescent mesoporous core-shell nanospheres emit strong green fluorescence (from Tb3+) in the middle of the visible region under 325 nm (3.8) excitation. The luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres can therefore be exploited as fluorescent probes in biomarkers or biolabeling, optical sensing, and drug delivery system. Further, these nanospheres could have potential use as scattering layers in dye-sensitized solar cells.

Facile incorporation of aggregation-induced emission materials into mesoporous silica nanoparticles for intracellular imaging and cancer therapy

Aggregation-induced emission (AIE) materials were facilely incorporated into mesoporous silica nanoparticles (MSNs) via one-pot surfactant templated method. Cell imaging and cancer therapy applications of such fluorescent MSNs were further explored. We demonstrated that AIE-MSN nanocomposites showed strong fluorescence and uniform morphology, making them promising for both cell imaging and cancer therapy.

Extension of the Stöber method to construct mesoporous SiO2 and TiO2 shells for uniform multifunctional core-shell structures

Core–shell nanoparticles (CSNs) have attracted considerable attention because of their promising applications in a wide range of fields. Recently, substantial efforts have been focused on the development of facile and versatile methods for preparing CSNs with mesoporous SiO(2) or TiO(2) shells because of their fascinating properties, such as high surface area, large pore channels and high pore volume. This Research News reviews the recent progress in facile, versatile and reproducible approaches which are simply extended from the well-known Stöber method to construct mesoporous SiO(2) and TiO(2) shells for uniform multifunctional core–shell nanostructures. Several strategies, including the surfactant-templating process, the long-chain organosilane-assisted approach, the phase transfer assisted surfactant-templating process, and the kinetics-controlled coating approach, are discussed. In addition, new trends in this field for the creation of multifunctional CSNs and novel nanostructures are highlighted.