Degradation Of Nanoparticles Research Articles

Greener Synthesis of Zinc Oxide Nanoparticles: Characterization and Multifaceted Applications.

Nanoparticles (NPs) have unique properties compared to their bulk counterparts, and they have potentials for various applications in many fields of life science. Green-synthesized NPs have garnered considerable interest due to their inherent features such as rapidity, eco-friendliness and cost-effectiveness. Zinc oxide nanoparticles (ZnO NPs) were synthesized using an aqueous extract of Kalanchoe blossfeldiana as a reducing agent. The resulting nanoparticles were characterized via X-ray diffraction (XRD), dynamic light scattering (DLS), UV-Vis spectroscopy, photoluminescence (PL), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The antimicrobial potential of the synthesized ZnO NPs against bacterial and fungal strains was examined by the disk diffusion method, and they showed a promising antibacterial and antifungal potential. The catalytic activity of the synthesized ZnO NPs in reducing methylene blue (MB) and eosin was studied via UV-Vis spectroscopy. The decolorization percentages of the MB and Eosin Y dyes were 84% and 94%, respectively, which indicate an efficient degradation of the ZnO NPs. In addition, the cytotoxic activity of the ZnO NPs on the HeLa cell line was evaluated via in vitro assay. The MTT assay results demonstrate a potent cytotoxic effect of the ZnO NPs against the HeLa cancer cell line.

Colitis-targeted hybrid nanoparticles-in-microparticles system for the treatment of ulcerative colitis

Nanoparticle (NP)-based drug delivery systems accumulate in the disrupted epithelium of inflamed colon tissue in ulcerative colitis. However, premature early drug release and uptake or degradation of NPs during their passage through the harsh gastric or intestinal environment compromise their therapeutic outcomes. This study aimed to develop an advanced colitis-targeted hybrid nanoparticles-in-microparticles (NPsinMPs) drug delivery system to overcome the aforementioned challenges. First, sustained drug releasing poly(lactic-co-glycolic acid) NPs were generated and further encapsulated in pH-sensitive Eudragit FS30D MPs to ensure complete drug protection in a gastric-like pH and for selective delivery of NPs to the colon. SEM and confocal microscopy for the NPsinMPs revealed successful NP encapsulation. NPsinMPs prevented drug release in an acidic gastric-like and intestinal-like pH and presented a sustained release thereafter at an ileal and colonic pH, indicating the degradation of the outer pH-sensitive MPs and release of NPs. Furthermore, in vivo imaging of gastrointestinal tract of a colitis mouse orally administered with fluorescent NPsinMPs revealed higher fluorescence intensities selectively in the colon, demonstrating the release of loaded NPs and their concomitant accumulation at the site of colon inflammation. NPsinMPs markedly mitigated experimental colitis in mice indicated by improved histopathological analysis, decreased myeloperoxidase activity, neutrophils and macrophage infiltration, and expression of proinflammatory cytokines in colonic tissues compared with NP-treated mice. The present results show the successful formulation of an NPsinMP-based drug delivery system and provide a platform to improve NP-based colon-targeted drug delivery through improved protection of encapsulated NPs and their payload in the early small intestine.

Evaluation on redox-triggered degradation of thioether-bridged hybrid mesoporous organosilica nanoparticles

Incorporation of degradable groups such as thioether bonds can make nanoparticles susceptible to be degraded by biological redox stimulus. Few studies have paid attention to effects of different surface properties of carriers on degradation behaviors between traditional mesoporous silica carriers and hybrid organosilica carriers, caused by inserted thioether groups. In this work, colloidal mesoporous silica (CMS) and hybrid colloidal mesoporous silica (HCMS) with different contents of doped thioether bonds are constructed to compare their physicochemical properties and degradability. With the increased amounts of doped thioether bonds, specific surface areas and Zeta potentials of HCMS nanoparticles decrease. Additionally, dynamic contact angle and the oil-water distribution coefficient are combined to characterize the hydrophobicity of CMS and HCMS nanoparticles. Therefore, after incorporating thioether bonds into the structure of carriers, the degradation behavior of HCMS nanoparticles in the medium were the result of weighing the advantages of degradable thioether bonds and disadvantages of decreased specific surface area and enhanced hydrophobicity of carriers. Experimental results displayed that, in the high concentration of reductive environment, HCMS carriers with doping proper proportion of thioether groups showed the fast degradation rate due to the cleaved thioether bonds as the dominant factor. The present work breaks the common views that all thioether bonds-bridged organosilica could become excellent biodegradable carriers, providing an objective perspective to evaluate the degradability of hybrid organosilica carriers.

Molten salt synthesis of CoFe2O4 and its energy storage properties

In this article, we report simple and scalable one-pot molten salt synthesis of CoFe2O4 as electrode material for Lithium ion batteries. X-ray diffraction studies along with Rietveld analysis showed a pure phase of CoFe2O4 with space group Fd-3m and crystallite size of 54 nm. As an anode material CoFe2O4 showed high initial discharge/charge capacity of 1556/1093 mA h g−1 and a reversible capacity of 926 mA h g−1 after 30 cycles with columbic efficiency of 99%. A relatively high reversible capacity of 594 mA h g−1 was observed at high current density of 1C (916 mA g−1) which shows the better reversibility of CoFe2O4 at high current density. As the current was reduced to 0.1C reversible capacity of 899 mA h g−1 was retained suggesting high rate performance of CoFe2O4. The long-term stability test, carried out using galvanostatic charge/discharge (GC) at a current density of 0.5C, showed a reversible capacity of 369 mA h g−1 at the end of 200th cycle. The structural and morphological evaluation of the sample after cycling, using ex-situ X-ray diffraction and ex-situ transmission electron microscopy, confirmed structural degradation and formation of metal nanoparticles, Li2O and amorphous nature of electrode material. The one-pot molten salt synthesis approach is quite simple and can be extended for large-scale production of electrode materials.

Alkalinity triggered the degradation of polydopamine nanoparticles

Polydopamine (PDA) has been found to be as functional materials in a wide range of applications. However, the degradation behavior and mechanism of PDA are still in debate. For well understanding the degradation, PDA nanoparticles (PDA NPs) were prepared by oxidation and self-polymerization of dopamine and employed to study the degradation properties. We systematically studied the degradation of PDA NPs by adjusting the pH value, temperature and alkali strength of the system. PDA NPs were more prone to degrade under alkaline conditions above pH 11.0, and the stronger the alkalinity (pH 13.0) induced the faster the degradation rate. The analysis results for the entire degradation process showed that the size of the PDA NPs firstly decreased and then the morphology of PDA NPs changed from spheres to nanosheets with degradation time. After 120 h of degradation, PDA was completely degraded into monomers and oligomers with three or four repeat units that can be soluble in water. Moreover, PDA showed good biocompatibility. This study would give a strong evidence to confirm the degradation of PDA and help for designing the new PDA materials in biomedical and environmental fields.

Mucoadhesive Nanoparticles for Drug Delivery to the Anterior Eye.

While the use of topical drops for the delivery of drugs to the anterior of the eye is well accepted, it is far from efficient with as little as 5% of the drug instilled on the eye actually reaching the target tissue. The ability to prolong the residence time on the eye is desirable. Based on the acceptability of 2-hydroxyethyl methacrylate based polymers in contact lens applications, the current work focuses on the development of a poly(2-hydroxyethyl methacrylate (HEMA)) nanoparticle system. The particles were modified to allow for degradation and to permit mucoadhesion. Size and morphological analysis of the final polymer products showed that nano-sized, spherical particles were produced. FTIR spectra demonstrated that the nanoparticles comprised poly(HEMA) and that 3-(acrylamido)phenylboronic acid (3AAPBA), as a mucoadhesive, was successfully incorporated. Degradation of nanoparticles containing N,N′-bis(acryloyl)cystamine (BAC) after incubation with DL-dithiothreitol (DTT) was confirmed by a decrease in turbidity and through transmission electron microscopy (TEM). Nanoparticle mucoadhesion was shown through an in-vitro zeta potential analysis.

Preparation of PDLLA and PLGA nanoparticles stabilized with PVA and a PVA-SDS mixture: Studies on particle size, degradation and drug release

The use of poly(vinyl alcohol) (PVA) and a PVA-sodium dodecyl sulfate mixture (PVA-SDS) for the colloidal stabilization of poly(dl-lactide) (PDLLA) and poly(dl-lactide-co-glycolide) (PLGA) nanoparticles (NPs) loaded with paclitaxel (PTX) was investigated. During the preparation of PDLLA and PLGA NPs via a single emulsion method, electrosteric-like stabilization imparted by the PVA-SDS led to the formation of smaller average particle diameter (Dp) than using only PVA which provided steric stabilization. It was found that, with the polymer composition of the NPs, the release profile can be tuned also, depending on whether PVA-SDS or PVA alone was used as stabilizer. The mechanism of the NP degradation and PTX release was studied as a function of time. The results obtained during 28 days were discussed in detail based on the evolutions of Dp, polymer molecular weight and its polydispersity index including the role of the electrosteric-like and steric stabilizers on the phenomenology involved.

In Vivo Single-Molecule Detection of Nanoparticles for Multiphoton Fluorescence Correlation Spectroscopy to Quantify Cerebral Blood Flow.

We present the application of multiphoton in vivo fluorescence correlation spectroscopy (FCS) of fluorescent nanoparticles for the measurement of cerebral blood flow with excellent spatial and temporal resolution. Through the detection of single nanoparticles within the complex vessel architecture of a live mouse, this new approach enables the quantification of nanoparticle dynamics occurring within the vasculature along with simultaneous measurements of blood flow properties in the brain. In addition to providing high resolution blood flow measurements, this approach enables real-time quantification of nanoparticle concentration, degradation, and transport. This method is capable of quantifying flow rates at each pixel with submicron resolution to enable monitoring of dynamic changes in flow rates in response to changes in the animal's physiological condition. Scanning the excitation beam using FCS provides pixel by pixel mapping of flow rates with subvessel resolution across capillaries 300 μm deep in the brains of mice.

Updating radical ring-opening polymerisation of cyclic ketene acetals from synthesis to degradation

Radical ring-opening polymerisation (RROP) of cyclic ketene acetals (CKAs) has gained momentum as it yields polyesters as biodegradable polymers from a radical polymerisation. In order to advance the polymerisation, some of its major limitations were addressed in the research presented, focussing on the four mainly used CKAs in modern research on RROP. Monomer synthesis has been updated towards a cobalt/TMSCl-based system that was performed reliably on several monomers at room temperature. Calculations using the density functional theory(DFT) revealed that the ring-opening step is energetically hampered in comparison to a ring-retaining reaction, which explained the challenges faced to promote the ring-opening reaction. Higher molecular weights up to four times the values reached by thermally initiated polymerisation were obtained by exploiting UV light and ultrasound as alternative methods to facilitate the polymerisation. The reaction procedure also influenced thermal properties of the polymers, which in turn affected the enzymatic degradation of nanoparticles based on those polymers. Altogether, the present study offers a holistic update to enhance the RROP of CKAs.

Photo-responsive degradable hollow mesoporous organosilica nanoplatforms for drug delivery

BackgroundStimulus-responsive degradable mesoporous organosilica nanoparticles (MONs) have shown great promise as drug carriers via enhancing the efficiency of drug delivery and accelerating the degradation of nanocarriers. However, it remains a great challenge to develop novel light-enabled spatial and temporal degradable MONs with both superior responsiveness for efficient anti-cancer drug delivery and safe exocytosis.ResultsWe report a novel photo-responsive degradable hollow mesoporous organosilica nanoplatform (HMONs@GOQD). The platform is based on organosilica nanoparticles (HMONs) containing singlet oxygen (1O2)-responsive bridged organoalkoxysilanes and wrapped graphene oxide quantum dots (GOQDs). The unique hollow mesoporous structure of the HMONs guarantees an excellent drug loading and release profile. During light irradiation, 1O2 produced by the GOQDs leads to the degradation of the organosilica nanoparticles, resulting in enhanced local drug release.ConclusionsWe carried out in vitro and in vivo experiments using DOX as a model drug; DOX-HMONs@GOQDs exhibited high biocompatibility, accelerated degradation, and superior therapeutic efficacy during light irradiation, indicating a promising platform for clinical cancer therapy.

Environmental-friendly degradation of clay-hybridized Cu nanoparticles by carboxylic acids

Green degradation method of Cu nanoparticles was investigated by stepwise oxidation with air and carboxylic acid. The Cu nanoparticles were synthesized directly on kaolinite, one of the layered clay minerals. By the air exposure, the Cu nanoparticles formed Cu2O shell, which was oxidized to Cu2+ by the carboxylic acid. Degradation rate was calculated by using the absorption band of Cu2+. As a result, the Cu nanoparticles were found to be degraded almost completely regardless of valence of the carboxylic acids, while the proton in the carboxy group was significant in the oxidation of Cu2O to Cu2+.

Combustion characteristic and aging behavior of bimetal thermite powders

Nanothermites have been employed as fuel additives in energetic formulations due to their higher energy density over CHNO energetics. Nevertheless, sintering and degradation of nanoparticles significantly limit the practical use of nanothermites. In this work, combustion characteristic and aging behavior of aluminum/iron oxide (Al/Fe2O3) nanothermite mixtures were investigated in the presence of micron-scale nickel aimed to produce bimetal thermite powders. The results showed that the alumina content in the combustion residue increased from 88.3% for Al/Fe2O3 nanothermite to 96.5% for the nanothermite mixture containing 20 wt% nickel. Finer particle sizes of combustion residue were obtained for the nanothermite mixtures containing nickel, indicative of the reduced agglomeration. Both results suggested a more complete combustion in the bimetal thermite powders. Aging behavior of the nanothermite mixture was also assessed by measuring the heat of combustion of the mixture before and after aging process. The reduction in heat of combustion of nanothermite mixtures containing nickel was less severe as compared to a significant decrease for the nanothermite mixture without nickel, indicating better aging resistance of the bimetal thermite powders.

Dye degradation, antimicrobial and larvicidal activity of silver nanoparticles biosynthesized from Cleistanthus collinus.

The present study aimed in green synthesis and characterization of silver nanoparticles (AgNPs) using the leaves of Cleistanthus collinus. The NPs showed various absorption peaks between 3402 cm−1 and 1063 cm−1. FTIR spectrum revealed the presence of OH group, alkene, aromatic hydrocarbon, aliphatic fluro compound and aliphatic chloro compounds. Scanning electron microscopic analysis revealed the particle size ranged from 30 to 50 nm. The biosynthesized NPs have potent activity against Shigella dysentriae, Staphylococcus aureus and Bacillus subtilis and the zone of inhibition was 21 ± 1, 20 ± 2, 16 ± 2 mm, respectively. Toxicity of the synthesized NPs was tested on green gram (Vigna radiata) seed at various concentrations (20–100%) and germination was induced by NPs treated seeds. Shoot length and root length was higher in NPs treated plant than control plant (p < 0.01). Elevated level of catalase (CAT) and superoxide dismutase (SOD) and about 13% CAT and 7% SOD activity registered than control. Superoxide dismutase activity of root and shoot varied based on the dosage of AgNPs (p < 0.01). Also, the NPs (1%) showed significant larvicidal activity on Aedes aegypti and 100% mortality was achieved after 24 h treatment. The green synthesized NPs reduced methylene blue and 4-nitrophenol significantly (p < 0.01). The colouration of methylene blue and 4-nitrophenol were considerably reduced after 60 min showed the potential of dye degrading ability.

Influence of Nickel concentration on the photocatalytic dye degradation (methylene blue and reactive red 120) and antibacterial activity of ZnO nanoparticles

This study assessed the synergistic effect of Ni concentration and ultrasonic assisted process on the photocatalytic dye degradation efficiency towards methylene blue (MB) and reactive red 120 (RR120) and antibacterial activity against various bacteria of ZnO nanoparticles. XRD confirms the absence of any other impurity peaks in Nickel (Ni) doped ZnO nanoparticles, disclose that Ni doping influences the lattice structure of Zn. The obvious red-shift with the increase of Ni concentration results in decreased band gap and transmittance. SEM micrograph confirms the formation of hexagonal rod and sheet like nanostructures in the Ni doped ZnO nanoparticles by the ultrasonic assisted co-precipitation method. The Ni doped ZnO nanoparticles control the recombination of charge carriers and increase the photocatalytic degradation of MB and RR120. The antibacterial result revealed that 5% Ni substituted sample is effective as an antibacterial agent to prevent the bacterial contamination. 5% Ni doped ZnO nanoparticles synthesized by ultrasonic assisted coprecipitation method is an excellent candidate for removal of methylene blue and bacteria.

Enhanced photocatalytic degradation and hydrogen evolution of ZnS nanoparticles by (Co, Er) co-doping

In this study, pristine, Co-doped, Er-doped, and (Co, Er) co-doped ZnS nanoparticles (NPs) were prepared through a simple co-precipitation technique. X-ray diffraction results indicated that Co and Er ions effectively replaced the Zn ions in tetrahedral sites. The adjustable optical bandgap for ZnS was accomplished via doping and co-doping. All the fabricated NPs portrayed identical blue emission with different fluorescence efficiencies. The (Co, Er) co-doped NPs exhibited enhanced photocatalytic dye (Malachite Green) degradation compared to those of the remaining NPs under artificial solar spectrum. In addition, these samples were measured for hydrogen production by water splitting through artificial solar light illumination. Among them, (Co, Er) co-doped NPs displayed the highest hydrogen production capability (9824 µmol h−1g−1) in 5 h.

Complex Relationship Between Iron Oxide Nanoparticle Degradation and Signal Intensity in Magnetic Particle Imaging.

Magnetic particle imaging (MPI), using superparamagnetic nanoparticles as an imaging tracer, is touted as a quantitative biomedical imaging technology, but MPI signal properties have never been characterized for magnetic nanoparticles undergoing biodegradation. We show that MPI signal properties can increase or decrease as iron oxide nanoparticles degrade, depending on the nanoparticle formulation and nanocrystal size, and degradation rate and mechanism. Further, we show that long-term in vitro MPI experiments only roughly approximate long-term in vivo MPI signal properties. Further, we demonstrate for the first time, an environmentally sensitive MPI contrast mechanism opening the door to smart contrast paradigms in MPI.

Degradable Poly(Methyl Methacrylate)-co-Methacrylic Acid Nanoparticles for Controlled Delivery of Growth Factors for Bone Regeneration.

Bone tissue engineering strategies have been developed to address the limitations of the current gold standard treatment options for bone-related disorders. These systems consist of an engineered scaffold that mimics the extracellular matrix and provides an architecture to guide the natural bone regeneration process, and incorporated growth factors that enhance cell recruitment and ingress into the scaffold and promote the osteogenic differentiation of stem cells and angiogenesis. In particular, the osteogenic growth factor bone morphogenetic protein 2 (BMP-2) has been widely studied as a potent agent to improve bone regeneration. A key challenge in growth factor delivery is that the growth factors must reach their target sites without losing bioactivity and remain in the location for an extended period to effectively aid in the formation of new bone. Protein incorporation into nanoparticles can both protect protein bioactivity and enable its sustained release. In this study, a poly(methyl methacrylate-co-methacrylic acid) nanoparticle-based system was synthesized incorporating a custom poly(ethylene glycol) dimethacrylate crosslinker. It was demonstrated that the nanoparticle degradation rate can be controlled by tuning the number of hydrolytically degradable ester units along the crosslinker. We also showed that the nanoparticles had high affinity for a model protein for BMP-2, and optimal conditions for maximum protein loading efficiency were elucidated. Ultimately, the proposed system and its high degree of tunability can be applied to a wide range of growth factors and tissue engineering applications. Impact Statement In this study, we developed a novel method of synthesizing nanoparticles with tunable degradation rates through the incorporation of a custom synthesized, hydrolytically degradable crosslinker. In addition, we demonstrated the affinity of the synthesized nanoparticles for a model protein for bone morphogenetic protein 2 (BMP-2). The tunability of these nanoparticles can be used to develop complex tissue engineering systems, for example, for the delivery of multiple growth factors involved at different stages of the bone regeneration process.

Revealing Sintering Kinetics of MoS2-Supported Metal Nanocatalysts in Atmospheric Gas Environments via Operando Transmission Electron Microscopy.

The decoration of two-dimensional (2D) substrates with nanoparticles (NPs) serve as heterostructures for various catalysis applications. Deep understanding of catalyst degradation mechanisms during service conditions is crucial to improve the catalyst durability. Herein, we studied the sintering behavior of Pt and bimetallic Au-core Pt-shell (Au@Pt core-shell) NPs on MoS2 supports at high temperatures under vacuum, nitrogen (N2), hydrogen (H2), and air environments by in situ gas-cell transmission electron microscopy (TEM). The key observations are summarized as effect of environment: while particle migration and coalescence (PMC) was the main mechanism that led to Pt and Au@Pt NPs degradation under vacuum, N2, and H2 environments, the degradation of MoS2 substrate was prominent under exposure to air at high temperatures. Pt NPs were less stable in H2 environment when compared with the Pt NPs under vacuum or N2, due to Pt-H interactions that weakened the adhesion of Pt on MoS2. Effect of NP composition: under H2, the stability of Au@Pt NPs was higher in comparison to Pt NPs. This is because H2 promotes the alloying of Pt-Au, thus reducing the number of Pt at the surface (reducing H2 interactions) and increasing Pt atoms in contact with MoS2. Effect of NP size: The alloying effect promoted by H2 was more pronounced in small size Au@Pt NPs resulting in their higher sintering resistance in comparison to large size Au@Pt NPs and similar size Pt NPs. The present work provides key insights into the parameters affecting the catalyst degradation mechanisms on 2D supports.

Platinum nanoparticles with TiO2–skin as a durable catalyst for photoelectrochemical methanol oxidation and electrochemical oxygen reduction reactions

Performance degradation of Pt nanoparticles is considered to be among the most severe problems for electrochemical reactions. Pt–TiO2 catalysts are widely studied due to the optical effect of TiO2, which is beneficial for electron transfer during methanol oxidation. However, different configurations of these catalysts are insufficient in research. Here, we report rationally designed Pt nanoparticles with TiO2-skin as electrocatalysts for methanol oxidations and oxygen reduction reactions. Methanol oxidation current densities of the Pt–TiO2 nanoparticles are largely improved under irradiation. When the catalysts are tortured successive at ultrahigh current up to 1.0 mA cm−2, the potential-increase is as small as 90 mV. It shows good stability with a peak current fades of 4% after 250 cycles under illumination, compared with 13% in the dark. It also exhibits a much better oxygen reduction durability compared with Pt/C. By mechanism analysis, we believe the excellence in photoelectrochemistry is attributed to the TiO2-skin. The electrons generated in TiO2 spontaneously migrate to Pt nanoparticles, which provide a partially reducing atmosphere to prevent Pt nanoparticles from ionization and dissolution.

Multimodal gadolinium oxysulfide nanoparticles for bioimaging: A comprehensive biodistribution, elimination and toxicological study

For some years now, gadolinium oxysulfide nanoparticles (NPs) appear as strong candidates for very efficient multimodal in vivo imaging by: 1) Magnetic Resonance (MRI), 2) X-ray Computed Tomography (CT) and 3) photoluminescence imaging. In this paper, we present a selection of results centered on the evaluation of physico-chemical stability, toxicity, bio-distribution and excretion mechanisms of Gd2O2S:Ln3+ nanoparticles intravenously injected in rats. Two formulations are here tested with a common matrix and different dopants: Gd2O2S:Eu3+5% and Gd2O2S:Yb3+4%/Tm3+0.1%. The NPs appear to be almost insoluble in pure water and human plasma but corrosion/degradation phenomenon appears in acidic conditions classically encountered in cell lysosomes. Whole body in vivo distribution, excretion and toxicity evaluation revealed a high tolerance of nanoparticles with a long-lasting imaging signal associated with a slow hepatobiliary clearance and very weak urinary excretion. The results show that the majority of the injected product (>60%) has been excreted through the feces after five months. Experiments have evidenced that the NPs mainly accumulate in macrophage-rich organs, that is mainly liver and spleen and to a lesser extent lungs and bones (mainly marrow). No significant amounts have been detected in other organs such as heart, kidneys, brain, intestine and skin. Gd2O2S:Ln3+ NPs appeared to be very well tolerated up to 400 mg/kg when administered intravenously. Statement of SignificanceSince 2011, we have focused our work on Gd2O2S nanoparticles (NPs) for multimodal bioimaging using fluorescence, Magnetic Resonance Imaging (MRI) and Computed Tomography with very efficient results already published. However, since the European Medicines Agency has concluded its review of gadolinium contrast agents, confirming recommendations to restrict the use of some linear gadolinium agents used in MRI, a particular attention must be paid to any new contrast media containing gadolinium. Therefore, we present in this paper a compilation of studies about toxicity, bio-distribution and excretion mechanisms of Gd2O2S:Ln3+ NPs intravenously injected into rats. We also present an in vitro kinetic study of NPs degradation in aqueous and biological media to provide some information on chemical and biological stability.