Biodegradable Nanoprobe for NIR-II Fluorescence Image-Guided Surgery and Enhanced Breast Cancer Radiotherapy Efficacy

Positive resection margin frequently exists in breast-conserving treatment (BCT) of early-stage breast cancer, and insufficient therapeutic efficacy is common during radiotherapy (RT) in advanced breast cancer patients. Moreover, a multimodal nanotherapy platform is urgently required for precision cancer medicine. Therefore, a biodegradable cyclic RGD pentapeptide/hollow virus-like gadolinium (Gd)-based indocyanine green (R&HV-Gd@ICG) nanoprobe is developed to improve fluorescence image-guided surgery and breast cancer RT efficacy. R&HV-Gd exhibits remarkably improved aqueous stability, tumor retention, and target specificity of ICG, and achieves outstanding magnetic resonance/second near-infrared (NIR-II) window multimodal imaging in vivo. The nanoprobe-based NIR-II fluorescence image guidance facilitates complete tumor resection, improves the overall mouse survival rate, and effectively discriminates between benign and malignant breast tissues in spontaneous breast cancer transgenic mice (area under the curve = 0.978; 95% confidence interval: 0.952, 1.0). Moreover, introducing the nanoprobe to tumors generated more reactive oxygen species under X-ray irradiation, improved RT sensitivity, and reduced mouse tumor progression. Notably, the nanoprobe is biodegradable in vivo and exhibits accelerated bodily clearance, which is expected to reduce the potential long-term inorganic nanoparticle toxicity. Overall, the nanoprobe provides a basis for developing precision breast cancer treatment strategies.

Revisiting the factors influencing the magnetic resonance contrast of Gd2O3 nanoparticles

Gadolinium oxide nanoparticles (GONs) have the potential to be one of the best candidates for the contrast agents of magnetic resonance imaging. Even though the influence of parameters on the relaxation has been substantially demonstrated, the variation of the r ₁ of GONs with a similar structure and surface chemistry implied our limited understanding. We herein synthesized GONs with adjustable size, shape, and crystallinity, modified them with a series of molecules with different acidities, and recorded their r ₁ values and imaging contrast. Our results showed that the isoelectric point could be regarded as an indicator of the relaxation covering the influence of both surface modification and size, which highlighted the impact of protons dissociated from the contrast agents. We further showed that the nanoparticles with lower crystallinity possess higher relaxivity, and this phenomenon manifested significantly under a low field. Our work clarified that the longitudinal relaxivity of Gd₂O₃ nanoparticles is sensitively dependent on the numbers of H⁺ generated from the surface and in the environment, which may shed light on developing high-performance nanoparticulate T ₁ contrast agents.

MRI relaxivity enhancement of gadolinium oxide nanoshells with a controllable shell thickness

The relaxation enhancement mechanism and MRI application of the designed core–shelled silica–Gd₂O₃ nanoparticle contrast agents were studied.

Encapsulation of Gadolinium Oxide Nanoparticle (Gd2O3) Contrasting Agents in PAMAM Dendrimer Templates for Enhanced Magnetic Resonance Imaging in Vivo

There has been growing interest in the research of nanomaterials for biomedical applications in recent decades. Herein, a simple approach to synthesize the G4.5-Gd₂O₃-poly(ethylene glycol) (G4.5-Gd₂O₃-PEG) nanoparticles (NPs) that demonstrate potential as dual (T₁ and T₂) contrasting agents in magnetic resonance imaging (MRI) has been reported in this study. Compared to the clinically popular Gd-DTPA contrasting agents, G4.5-Gd₂O₃-PEG NPs exhibited a longer longitudinal relaxation time (T₁) and better biocompatibility when incubated with macrophage cell line RAW264.7 in vitro. Furthermore, the longitudinal relaxivity (r₁) of G4.5-Gd₂O₃-PEG NPs was 53.9 s^-1 mM^-1 at 7T, which is equivalent to 4.8 times greater than to the Gd-DTPA contrasting agents. An in vivo T₁-weighted MRI results revealed that G4.5-Gd₂O₃-PEG NPs significantly enhanced signals in the intestines, kidney, liver, bladder, and spleen. In addition, the T₂-weighted MRI results revealed darker contrast in the kidney, which proves that G4.5-Gd₂O₃-PEG NPs can be exploited as T₁ and T₂ contrasting agents. In summary, these findings suggest that the G4.5-Gd₂O₃-PEG NPs synthesized by an alternative approach can be used as dual MRI contrasting agents.

Europium-Doped Gd2O3 Nanotubes Increase Bone Mineral Density in Vivo and Promote Mineralization in Vitro

Europium-doped Gd₂O₃ nanotubes (Gd₂O₃:Eu³⁺ NTs) have been extensively applied in the field of bioscience for their photostability and magnetic properties. Nevertheless, the distribution and interaction between Gd₂O₃:Eu³⁺ NTs and metabolism of bone are not yet sufficiently understood. In this study, a systematic study of the toxicity and distribution of Gd₂O₃:Eu³⁺ NTs in mice after oral administration was carried out. The results showed that a small number of the Gd₂O₃:Eu³⁺ NTs could pass through biological barriers into the lung, liver, and spleen, but a high concentration was observed in bone. Furthermore, the effects of Gd₂O₃:Eu³⁺ NTs on bone metabolism were systematically studied in vitro and in vivo when accumulating in bone. After being administered to mice, the Gd₂O₃:Eu³⁺ NTs extremely enhanced the bone mineral density and bone biomechanics. In vitro the Gd₂O₃:Eu³⁺ NTs increased the alkaline phosphatase (ALP) activity and mineralization and promoted the expression of osteogenesis genes in preosteoblasts MC3T3-E1 through activation of the BMP signaling pathway. This study will be significant for appropriate application of Gd₂O₃:Eu³⁺ NTs in the biomedical field and expounding the molecular mechanism of bone metabolism.

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials, thereby enabling the fabrication of bioconjugates and heterogeneous catalysts. Accurate size control of LSPC-synthesized materials ranging from quantum dots to submicrometer spheres and recent upscaling advancement toward the multiple-gram scale are helpful for extending the applicability of LSPC-synthesized nanomaterials to various fields. By discussing key reports on both the fundamentals and the applications related to laser ablation, fragmentation, and melting in liquids, this Article presents a timely and critical review of this emerging topic.

Germanium Sub-Microspheres Synthesized by Picosecond Pulsed Laser Melting in Liquids: Educt Size Effects

Pulsed laser melting in liquid (PLML) has emerged as a facile approach to synthesize submicron spheres (SMSs) for various applications. Typically lasers with long pulse durations in the nanosecond regime are used. However, recent findings show that during melting the energy absorbed by the particle will be dissipated promptly after laser-matter interaction following the temperature decrease within tens of nanoseconds and hence limiting the efficiency of longer pulse widths. Here, the feasibility to utilize a picosecond laser to synthesize Ge SMSs (200~1000 nm in diameter) is demonstrated by irradiating polydisperse Ge powders in water and isopropanol. Through analyzing the educt size dependent SMSs formation mechanism, we find that Ge powders (200~1000 nm) are directly transformed into SMSs during PLML via reshaping, while comparatively larger powders (1000~2000 nm) are split into daughter SMSs via liquid droplet bisection. Furthermore, the contribution of powders larger than 2000 nm and smaller than 200 nm to form SMSs is discussed. This work shows that compared to nanosecond lasers, picosecond lasers are also suitable to produce SMSs if the pulse duration is longer than the material electron-phonon coupling period to allow thermal relaxation.

Structure and dysprosium dopant engineering of gadolinium oxide nanoparticles for enhanced dual-modal magnetic resonance and fluorescence imaging

We report a novel multi-functional nanoarchitecture of Gd₂O₃:Dy³⁺ shell on silica core that enables unique multi-color living cell imaging and remarkable in vivo magnetic resonance imaging.

Fabrication of an acetone sensor based on facile ternary MnO2/Gd2O3/SnO2 nanosheets for environmental safety

The facile hydrothermally synthesized (at low temperature, in alkaline medium of pH 10.5) nanosheets (NSs) of MnO₂/Gd₂O₃/SnO₂ are well crystalline-doped ternary metal oxides.

Ethyl Acetate Abatement on Copper Catalysts Supported on Ceria Doped with Rare Earth Oxides

Different lanthanide (Ln)-doped cerium oxides (Ce_0.5Ln_0.5O_1.75, where Ln: Gd, La, Pr, Nd, Sm) were loaded with Cu (20 wt. %) and used as catalysts for the oxidation of ethyl acetate (EtOAc), a common volatile organic compound (VOC). For comparison, both Cu-free (Ce-Ln) and supported Cu (Cu/Ce-Ln) samples were characterized by N₂ adsorption at −196 °C, scanning/transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction in H₂. The following activity sequence, in terms of EtOAc conversion, was found for bare supports: CeO₂ ≈ Ce_0.5Pr_0.5O_1.75 > Ce_0.5Sm_0.5O_1.75 > Ce_0.5Gd_0.5O_1.75 > Ce_0.5Nd_0.5O_1.75 > Ce_0.5La_0.5O_1.75. Cu addition improved the catalytic performance, without affecting the activity order. The best catalytic performance was obtained for Cu/CeO₂ and Cu/Ce_0.5Pr_0.5O_1.75 samples, both achieving complete EtOAc conversion below ca. 290 °C. A strong correlation was revealed between the catalytic performance and the redox properties of the samples, in terms of reducibility and lattice oxygen availability. Νo particular correlation between the VOC oxidation performance and textural characteristics was found. The obtained results can be explained in terms of a Mars-van Krevelen type redox mechanism involving the participation of weakly bound (easily reduced) lattice oxygen and its consequent replenishment by gas phase oxygen.

Geometrically confined ultrasmall gadolinium oxide nanoparticles boost the T(1) contrast ability

High-performance magnetic resonance imaging (MRI) contrast agents and novel contrast enhancement strategies are urgently needed for sensitive and accurate diagnosis. Here we report a strategy to construct a new T1 contrast agent based on the Solomon-Bloembergen-Morgan (SBM) theory. We loaded the ultrasmall gadolinium oxide nanoparticles into worm-like interior channels of mesoporous silica nanospheres (Gd2O3@MSN nanocomposites). This unique structure endows the nanocomposites with geometrical confinement, high molecular tumbling time, and a large coordinated number of water molecules, which results in a significant enhancement of the T1 contrast with longitudinal proton relaxivity (r1) as high as 45.08 mM(-1) s(-1). Such a high r1 value of Gd2O3@MSN, compared to those of ultrasmall Gd2O3 nanoparticles and gadolinium-based clinical contrast agents, is mainly attributed to the strong geometrical confinement effect. This strategy provides new guidance for developing various high-performance T1 contrast agents for sensitive imaging and disease diagnosis.

Smart polymeric particle encapsulated gadolinium oxide and europium: theranostic probes for magnetic resonance/optical imaging and antitumor drug delivery

Paramagnetic, luminescent, and temperature/pH-responsive polymeric particles with MR/optical imaging and antitumor drug delivery capability are prepared by emulsifier-free emulsion polymerization.

PAMAM dendrimer based targeted nano-carrier for bio-imaging and therapeutic agents

In the last several decades, researchers have focused on developing suitable drug carriers to deliver pharmaceutical agents to treat cancer diseases.

In vivo biodistribution and toxicity of Gd2O3:Eu3+ nanotubes in mice after intraperitoneal injection

To better understand the potential impact of Gd₂O₃:Eu³⁺ nanotubes on human health, we investigated their biodistribution, subacute toxicity, and hepatic injury in mice under different dosages (4.0, 40.0, and 400.0 mg kg⁻¹).

Molecular architecture control in synthesis of spherical Ln-containing nanoparticles

The type of surfactant and the nature of the dispersed and continuous phases forming a miniemulsion, control the size and chemical composition of Ln-based nanoparticles.

Sub-10 nm monoclinic Gd2O3:Eu3+ nanoparticles as dual-modal nanoprobes for magnetic resonance and fluorescence imaging

Monoclinic Gd2O3:Eu(3+) nanoparticles (NPs) possess favorable magnetic and optical properties for biomedical application. However, how to obtain small enough NPs still remains a challenge. Here we combined the standard solid-state reaction with the laser ablation in liquids (LAL) technique to fabricate sub-10 nm monoclinic Gd2O3:Eu(3+) NPs and explained their formation mechanism. The obtained Gd2O3:Eu(3+) NPs exhibit bright red fluorescence emission and can be successfully used as fluorescence probe for cells imaging. In vitro and in vivo magnetic resonance imaging (MRI) studies show that the product can also serve as MRI good contrast agent. Then, we systematically investigated the nanotoxicity including cell viability, apoptosis in vitro, as well as the immunotoxicity and pharmacokinetics assays in vivo. This investigation provides a platform for the fabrication of ultrafine monoclinic Gd2O3:Eu(3+) NPs and evaluation of their efficiency and safety in preclinical application.

A general top-down approach to synthesize rare earth doped-Gd2O3 nanocrystals as dualmodal contrast agents

A general strategy, combining laser ablation in liquid with a standard solid state reaction technique, is developed to prepare dualmodal contrast agents for fluorescence and magnetic resonance imaging applications.