Hydrothermal Co-precipitation Method Research Articles

Synergistic Effect of Layered Double Hydroxides Nanodosage Form to Induce Apoptosis and Ferroptosis in Breast Cancer.

Breast cancer is the most common cancer in women and one of the leading causes of cancer death worldwide. Ferroptosis, a promising mechanism of killing cancer cells, has become a research hotspot in cancer therapy. Simvastatin (SIM), as a potential new anti-breast cancer drug, has been shown to cause ferroptosis of cancer cells and inhibit breast cancer metastasis and recurrence. The purpose of this study is to develop a novel strategy boosting ferroptotic cascade for synergistic cancer therapy. In this paper, iron base form of layered double hydroxide supported simvastatin (LDHs-SIM) was synthesized by hydrothermal co-precipitation method. The characterization of LDHs-SIM were assessed by various analytical techniques, including ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). Biological activity, ferroptosis mechanism and biocompatibility were analyzed through in vivo and in vitro analysis, so as to evaluate its therapeutic effect on breast cancer. The constructed LDHs-SIM nanosystem can not only release SIM through mevalonate (MVA) pathway, inhibit the expression of glutathione peroxidase 4 (GPX4), inhibit the expression of SLC7A11 and reduce the synthesis efficiency of GSH, but also promote the accumulation of Fe2+ in cells through the release of Fe3+, and increase the intracellular ROS content. In addition, LDHs-SIM nanosystem can induce apoptosis of breast cancer cells to a certain extent, and achieve the synergistic effect of apoptosis and ferroptosis. In the present study, we demonstrated that nanoparticles of layered double hydroxides (LDHs) loaded with simvastatin were more effective than a free drug at inhibiting breast cancer cell growth, In addition, superior anticancer therapeutic effects were achieved with little systemic toxicity, indicating that LDHs-SIM could serve as a safe and high-performance platform for ferroptosis-apoptosis combined anticancer therapy.

The long rod-shaped Sr2 MgSi2 O7 :Eu2+ ,Dy3+ with ultrahigh afterglow performance.

The afterglow properties of long afterglow luminescent materials are greatly affected by their defects, which are distributed on the grain surface. Increasing the exposed surface area is an important method to improve the afterglow performance. In this research, long rod-shaped long afterglow materials Sr2 MgSi2 O7 :Eu2+ ,Dy3+ were prepared using the hydrothermal-coprecipitation method. When the reaction time reached 96 h, the length of the afterglow materials could grow to 2mm, and the sintering temperature was just 1150°C. The emission spectra of all obtained samples upon excitation at 397 nm had a maximum of 465 nm, which belonged to the representative transition of Eu2+ . The initial brightness was 1.35 cd/m2 . The afterglow time could reach 19 h, giving a good afterglow performance. The research on this kind of material has essential significance in the exploration of luminescence mechanisms and their applications.

Design of a novel magnetic composite catalyst with highly efficient cobalt circulation for activating peroxymonosulfate to degrade tetracycline

In this study, a magnetic CoFe2O4/Co2O3/Na-X Zeolite (CFCOZ) composite catalyst was prepared via a co-precipitation hydrothermal method. Comprehensive characterizations suggest that the porous shell layer composed of CoFe2O4 and Co2O3 nanoparticles is evenly supported on Na-X zeolite. The specific surface area of CFCOZ is 266.93 m2/g. CFCOZ was exploited to catalyze peroxymonosulfate (PMS) to degrade tetracycline (TC). Catalytic degradation experiments indicated that the TC removal rate in the PMS/CFCOZ system was higher than that in the CoFe2O4/zeolite/PMS oxidation system. The highest degradation rate reached 96.6 % ([PMS] = 1 mM, 0.2-g/L CFCOZ, [TC] = 20 mg/L, initial pH = 7, room temperature). Several influence factors were investigated, including initial solution pH, PMS concentration, and CFCOZ dosage, etc. on the TC degradation. Electron paramagnetic resonance spectroscopy and reactive species scavenging experiments showed that 1O2, SO4−, and O2− played the predominant role in the TC removal. The possible catalytic degradation mechanism was proposed. It is found that CoFe2O4 and Co2O3 could synergistically activate PMS, and enhance the circulation efficiency between Co2+ and Co3+ to promote the generation of ROS. The cyclic experiments and characterization results between the fresh and the used CFCOZ showed its continuous catalytic activity and good structural stability.

Efficient resonance energy transfer study of BaClF: Ce3+ to Tb3+

Ce3+/Tb3+ co-doped BaClF luminescent materials with highly efficient green luminescent properties. The phosphor was synthesized by a co-precipitation hydrothermal method, and the structure and morphology of the phosphor were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS). The photoluminescence properties of the prepared products were investigated and the energy transfer efficiencies were calculated for BaClF:3.0 mol% Ce3+, ymol% Tb3+ ( y = 0–0.5). By adjusting the doping concentration of Tb3+ ions in BaClF: Ce3+, Tb3+ phosphors, the luminescent color of the phosphor can be easily changed from blue to green. The Ce3+ and Tb3+ co-doped BaClF phosphor shows strong PL emission in the green region due to the resonance energy transfer from Ce3+ to Tb3+. The energy transfer mechanism of Ce3+ and Tb3+ co-doped BaClF samples was analyzed based on the energy level relationship between Ce3+ and Tb3+. The energy transfer efficiency from Ce3+ to Tb3+ was calculated and found to be up to 89.63%. These results suggest that BaClF: Ce3+, Tb3+ fluorescent material can be a potential green luminescent material for optoelectronic applications.

Investigating the impact of structural defects in MWCNT/MnFe2O4 nanocomposite for efficient photodegradation of cationic dye

The co-precipitation hydrothermal method was used to prepare MWCNT (0.01g and 0.04g)/MnFe2O4 composites and the valence state elemental compositions were verified with XPS. The TEM micrograph revealed that the functionalized MWCNTs were well-dispersed in the matrix and retained their tubular structure. PL analysis indicates an increase in electron-hole pair separation, electron trapping in the MWCNT and an increase in structural defects. The result of positron annihilation lifetime spectroscopy (PALS) reveals that the concentration of composite surface defect increases with CNT. Additionally, these findings show that the vacancy clusters and voids are more prominent in the interface of the MWCNT/MnFe2O4 composite compared to the MnFe2O4 particle surface. N2 adsorption-desorption isotherms analysis confirmed the surface area change in the composite. Notably, the MWCNT/MnFe2O4 composite exhibited significantly enhanced photocatalytic activity compared to pure MnFe2O4, leading to superior efficiency in the removal of methylene blue (MB).

Efficient Degradation of Rhodamine B with the BiOCl/Bi2Fe4O9 Heterojunction Photocatalyst.

BiOCl/Bi2Fe4O9 photocatalyst was prepared by a coprecipitation-hydrothermal method. The heterojunction structure generated by the composite of BiOCl and Bi2Fe4O9 reduced the electron-hole recombination efficiency and improved the degradation rate of RhB. At 240 min, 20% BiOCl/Bi2Fe4O9 represented the excellent degradation effect on 10 mg/L RhB; the degradation efficiency reached 99.56%; and the reaction rate constant was 0.01534 min-1, which was 5.76 times and 6.06 times that of Bi2Fe4O9 and BiOCl, respectively. The main active substance of the photocatalytic degradation of dyes was superoxide radical O2-·. Five cycles of the experiment proved the relative stability of BiOCl/Bi2Fe4O9.

Determination of the Catalytic Activity of a Peroxidase-like Nanozyme and Differences among Layered Double Hydroxides with Different Anions and Cations.

Nanomaterials with enzyme-like activity, namely, nanozymes, have been widely used as substitutes for natural enzymes, and they show excellent potential for application in many fields, such as biotechnology, environmental chemistry, and medicine. Layered double hydroxides (LDHs) are inorganic nanomaterials with adjustable compositions, simple preparation methods, and low costs and are some of the most promising candidate materials for the preparation of nanozymes. Here, we studied the syntheses and peroxidase-like activities of LDHs with four anions and four cations. First, LDHs prepared by the coprecipitation-hydrothermal method adopted hexagonal lamellar structures with good dispersion and uniform particle sizes. The Lambert-Beer law showed that the prepared LDHs exhibited good enzymatic activity. Later, the Km and Vmax values of the LDHs with different anionic/cationic materials intercalated into their structures were compared. Under the optimum conditions, the Vmax of Mg2Al-NO3-LDH was 7.35 × 10-2, which is 2-4 times higher than that of the LDHs containing other anions; the Vmax values of NiFe-LDH and FeAl-LDH were 0.152 and 0.284, respectively, which are 10 times higher than those of the LDHs with other cations. Importantly, according to kinetic analyses of the enzymatic reactions, the effects of Fe2+ and Fe3+ on the LDH enzyme activity were greater than those of the intercalated anions. This study showed that NiFe-LDH and FeAl-LDH with high catalytic activities are candidate materials for peroxidase simulations, which may provide new strategies for the application of LDHs in biosensors, antioxidants, biotechnology, and other nanozyme applications.

Effective peroxydisulfate activation by CQDs-MnFe2O4@ZIF-8 catalyst for complementary degradation of bisphenol A by free radicals and non-radical pathways

The present study reported fabrication of novel carbon quantum dots-MnFe2O4@ZIF-8 (CQDs-MFO@ZIF-8) by using co-precipitation hydrothermal method for activation of peroxydisulfate (PDS) to degrade bisphenol A (BPA), one of important emerging organic pollutants in water environment. CQDs-MFO@ZIF-8 served as a highly efficient thermal activated PDS catalyst with high catalytic degradation efficiency, reusability and stability. The catalyst achieved almost completely removal of 20.0 mg/L BPA within 5.0 min, and the degradation efficiency remained higher than 83% after 5 consecutive cycles. Free radicals (•OH, SO4•− and •O2−) and non-free radicals (1O2) were generated in the thermal PDS-activation system, in which singlet oxygen (1O2) played a dominant role in the degradation of BPA. The potential toxicity of BPA degradation intermediates was analyzed upon the culture of E. coli and Chlorella sorokiniana by using Ecological Structure-Activity Relationship Model (ECOSAR) program. The catalytic performances of BPA degradation by CQDs-MFO@ZIF-8 were evaluated for treatment of different practical water samples to further verify the feasibility of practical applications. This study provides proof-in-concept demonstration of new nanomaterials for enhanced catalytic water decontamination.

Mn doping enhances the photocatalytic performance of Bi2Fe4O9 photocatalyst

Bi2Fe4(1-x)Mn4xO9 photocatalyst was prepared by the coprecipitation-hydrothermal method. After doping Mn2+, the photogenerated carrier recombination efficiency of Bi2Fe4O9 was reduced, the electron transfer efficiency was accelerated, and had a good degradation effect for RhB. When Mn2+ doping was 6%, the degradation effect of organic dyes was very good, reaching 82.29%, and the reaction rate constant was 0.00665min−1, which was 2.5 times that of Bi2Fe4O9. The main active component of the dye degradation process was ·OH, which was consistent with that of Bi2Fe4O9.

Synthesis of Z-type spherical B-g-C3N4/Bi2WO6 heterojunctions for enhanced rhodamine B degradation

A spherical B-g-C3N4/Bi2WO6 heterojunction photocatalyst was synthesized using the hydrothermal coprecipitation method. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (DRS) showed that B-g-C3N4 was uniformly dispersed on the Bi2WO6 surface through a strong chemical bond, reducing the energy bandgap of Bi2WO6. The outcomes of the experiment regarding the photocatalytic degradation of rhodamine B (RhB) demonstrated a notable enhancement in the degradation rate for the 1:3 BCN/BWO composite. Specifically, the degradation rate was found to be 76 times greater than that of B-g-C3N4 and 7 times higher than that of Bi2WO6. Furthermore, a photocatalytic degradation mechanism was proposed based on the results of ultraviolet photoelectron spectroscopy (UPS) and free radical capture experiments. The direct Z-type B-g-C3N4/Bi2WO6 heterojunction structure promotes the effective separation of photogenerated carriers and enhances their oxidation-reduction ability.

Resource utilization of spent metal ions from acid-leaching clay to fabricate adsorbents with antibacterial activity for removal of antibiotics

With the popularity of environment friendly, low-carbon, sustainable, and high-quality development, the reuse of waste resources has attracted more and more attention. In this study, the functional Zn-based mixed metal oxides (Zn-MMOs) were facilely fabricated by ZnO-assisted hydrothermal coprecipitation method using the spent metal ions of Mg2+, Al3+, and Fe3+ after acid-leaching clay for the removal of antibiotics and hazard microorganisms from water. The results suggested that the composition, microstructure, adsorption, and antibacterial activity of Zn-MMOs depended on the added amount of ZnO. When the molar ratio of M2+/M3+ was 8, the obtained Zn-MMOs presented the maximum adsorption capacities for tetracycline and chlortetracycline of 409 and 693 mg/g, respectively. Meanwhile, Zn-MMOs exhibited similar antibacterial activity to that of commercial ZnO against Staphylococcus aureus and Escherichia coli, which could effectively eliminate microbial contaminants in the water environment. This work provided a collaborative solution for the resource utilization of wastes and the pollution treatment of wastewater, which played a significant positive role in promoting green economy and sustainable development.

MnFe2O4/zeolite composite catalyst for activating peroxymonosulfate to efficiently degrade antibiotic

To design a catalyst with high catalytic activity and reusability for activating peroxymonosulfate (PMS) to degrade antibiotic, magnetic MnFe2O4/zeolite (MFZ) catalyst was prepared by one-pot co-precipitation hydrothermal method. Comprehensive characterizations indicate MnFe2O4 nanoparticles were supported on the surface of Na-A zeolite. The saturation magnetization of MFZ is 12.85 emu/g, which is sufficient for magnetic solid–liquid separation. The removal of tetracycline in MFZ/PMS oxidation system could reach 96.4%, which was more than 2.7 times of that using PMS alone. And after 5 cycles, the degradation could still reach 80.4%. Mechanism analysis suggests that 1O2 and O2•- played predominant roles in the advanced oxidation process.

SnO2 nano particles Co-doped by Co and Ag: Microstructural, photocatalytic, magnetic, and Electric studies

The optical, photocatalyst, magnetic, and electric properties along with the microstructure of tin oxide co-doped by Ag and Co were investigated. Co-precipitation hydrothermal method was performed to produce nanoparticles of Pure SoO2 and Sn0.96-xCoxAg0.04O2 (x = 0, 0.02, and 0.04) compounds. Then, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), energy-dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectra (DR), UV–Vis spectroscopy techniques were performed to evaluate the compounds. The appropriate doping of Ag and Co was observed, with the formation of no new. Morphological features stayed unchanged, with the exemption of particle size reduction from 52.3 nm to 45.5 nm due to the presence of Ag. The presence of Co led to more homogeneous particle size distribution. The oxygen vacancy defects rose with the increase in the level of dopants. Band gap energy of pure SnO2 decreased from 3.63 eV to 3.45 eV in the presence of silver; and Co increased this energy. P-hydroxybenzoic acid photodegradation was enhanced up to 98% after 60 min by co-doping. Ag/Co co-doping enhanced magnetization saturation and coercivity of tin oxide up to 0.106 emu/g and 1890 Oe, respectively. The conductivity along with dielectric constant of tin oxide rose remarkably due to co-doping of Ag and Co.

Ca–La layered double hydroxide (LDH) for selective and efficient removal of phosphate from wastewater

Adsorption showed advantages in removing phosphorus (P) at low concentrations. Desirable adsorbents should have sufficiently high adsorption capacity and selectivity. In this study, a Ca–La layered double hydroxide (LDH) was synthesized for the first time by using a simple hydrothermal coprecipitation method for phosphate removal from wastewater. A maximum adsorption capacity of 194.04 mgP/g was achieved, ranking on the top of known LDHs. Adsorption kinetic experiments showed that 0.02 g/L Ca–La LDH could effectively reduce PO43–P from 1.0 to <0.02 mg/L within 30 min. With the copresence of bicarbonate and sulfate at concentrations 17.1 and 35.7 times of that of PO43–P, the Ca–La LDH showed promising selectivity towards phosphate (with a reduction in the adsorption capacity of <13.6%). In addition, four other (Mg–La, Co–La, Ni–La, and Cu–La) LDHs containing different divalent metal ions were synthesized by using the same coprecipitation method. Results showed much higher P adsorption performance of the Ca–La LDH than those LDHs. Field Emission Electron Microscopy (FE-SEM)-Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), and mesoporous analysis were performed to characterize and compare the adsorption mechanisms of different LDHs. The high adsorption capacity and selectivity of the Ca–La LDH were mainly explained by selective chemical adsorption, ion exchange, and inner sphere complexation.

A Facile Approach of Fabricating Bifunctional Catalysts for Redox Applications by Uniformly Immobilized Metallic Nanoparticles on NiCr LDH

This study discloses the development of NiCr LDH, Ag@NiCr LDH, and Pd@NiCr LDH bifunction catalysts using a hydrothermal coprecipitation method followed by sol immobilization of metallic nanoparticles. The structures and morphologies of the synthesized nanocomposites were analyzed using FTIR, XRD, XPS, BET, FESEM-EDX, and HRTEM. The catalytic effectiveness of the samples was evaluated by tracking the progression of NaBH4-mediated nitrobenzene (NB) reduction to aniline and CO oxidation using UV-visible spectrophotometry and an infrared gas analyzer, respectively. Pd@NiCr LDH displayed much higher performance for both reactions than the bare NiCr LDH. The catalyst Pd@NiCr LDH showed robust catalytic activity in both the oxidation of carbon monoxide (T50% (136.1 °C) and T100% (200.2 °C)) and NaBH4-mediated nitrobenzene reduction (98.7% conversion and 0.365 min-1 rate constant). The results disclose that the Ni2+@ Cr3+/Cr6+ @Pd° ion pairs inside the LDH act as a charge transfer center and hence significantly enhance the catalytic performance. As a result, this research offers the novel NiCr LDH catalyst as a bifunctional catalyst for air depollution control and the organic transformation process.

Nanozyme catalytic mimetic effect of iron oxide nanoparticles hybrids with cellulosic matrices and its synergism with microorganisms

Iron Oxide Nanoparticles (IONPs) are generally assumed to be biologically inert, presenting chemical stability and low toxicity, and they can be hybridized with cellulosic matrixes aiming for biological applications (e.g. nanozymes). Two hydrothermal coprecipitation methods were applied, aiming to produce 2 different size Iron oxide nanoclusters, using ferric chloride and ferrous chloride, as well as nitrocellulose and cellulosic residues for the hybrids. The obtained materials were tested for catalytic effect in comparison and in synergy with catalase-positive P. aeruginosa, S. aureus, and B. subtilis bacterial strains. The catalytic effect was observed for all obtained materials and microorganisms, Due to the bivalent and trivalent iron molecules distributed along IONP cubic crystalline inverse spinel structures. Michaelis-Menten constant (Km) of IONP-and hybrids was higher in synergy with S. aureus in comparison with the results obtained by the microorganism alone, for instance, the best enzymatic efficiency for O2 release from hydrogen peroxide among the tested microorganisms. However, no significant difference was observed for most of the obtained materials alone. On the other hand, IONPs may help microorganisms as mimetic catalytic enzymes, when applied in synergy whit them.

Effect of Fe3+ and/or PO43– Doping on the Electrochemical Performance of LiNi0.5Mn1.5O4 Cathode Material for Li-Ion Batteries

An Fe3+/PO43– codoped LiNi0.5Mn1.4667Fe0.02P0.0133O4 sample has been prepared by a coprecipitation–hydrothermal method followed by two-step calcination. A novel wet chemical route, using FeSO4 rather than Fe2(SO4)3 as the Fe3+ source and NaH2PO4 as the PO43– source, is adopted to obtain uniform codoping of Fe3+ and PO43– ions in a carbonate precursor according to the precipitation–dissolution–transformation mechanism. For comparison, Fe3+-doped and PO43–-doped samples have been also synthesized via the same route. The effects of Fe3+/PO43– codoping and single doping on the crystalline structure, morphology, and electrochemical performance of LiNi0.5Mn1.5O4 are investigated. Compared with pristine and single doped samples, the codoped sample shows better electrochemical performance, with a specific discharge capacity of 125.2 mAh g–1 at 10 C and a capacity retention rate of 85.9% after 200 cycles at 1 C, under the synergy of Fe3+/PO43– codoping, including enhanced crystallinity, decreased Mn3+ content, significantly reduced primary particle size and secondary agglomeration, as well as the appearance of (110) surfaces in truncated octahedral primary particles.

A persulfate oxidation system for removing acid orange from aqueous solution: Evaluation and degradation mechanism

Peroxymonosulfate-based advanced oxidation (PMS-AOP) is a promising technology for the degradation of environmental pollutants. PMS can be activated by various transition metals, especially cobalt-based catalysts, but pure cobalt catalyst suffers from severe metal leakage and poor cyclicality. This study synthesized NiCo2O4 using a co-precipitation hydrothermal method. The structures, morphologies, and chemical states of the prepared catalysts were hexagonal sheet structures. The activation of PMS by catalyst (NiCo2O4) is investigated in a PMS/carbonate (PC) system for Orange II degradation. The observed pseudo-first-order rate constants (k1) were assessed by the effects of different water matrices and operation conditions. The results show that kobs with NiCo2O4 were increased by 13 times than that of treatment without NiCo2O4. This was mainly due to Co3+ and Ni3+ act as electron acceptors to capture electrons from the PMS/PC system, forming a good redox cycle with HSO5−/SO5− and oxidizing Co2+/Ni2+ to produce a large amount of more active components (e.g., 1O2 and SO4⋅-). The good reusability and high stability of NiCo2O4 were demonstrated by five recycle tests. These results suggest that the NiCo2O4/PC system is an efficient and stable method of pollution remediation.

Ni2+ grafted Ag3PO4: Enhanced photocatalytic performance under visible light

New visible light photocatalysts based on Ag3PO4 (AgP) grafting with Ni2+ at three different percentages have been synthesized by coprecipitation-hydrothermal method. SEM/EDX, XRD and FTIR characterization revealed that all the samples present particles with a smooth surface spherical morphology. Dissimilarities were recorded in the particle size, grafted Ag3PO4 (Ni-AgP) undergo a reduction in diameter with the increase of the content of Ni2+. The unit cell parameters of the centered cubic structure of the samples are different from each other which suggested a possible integration of nickel in the outer layers but with the denial of the possibility of reaching the inner layers. The photocatalytic performance was evaluated in methyl orange (MO) degradation under different conditions of solution pH and MO concentration. It was found that nickel grafting resulted in enhanced photocatalytic activity which is correlated to Ni2+content. The enhancement in the performance is attributed to the synergistic effect of AgP and surface-suspended Ni2+ clusters which serve as acceptors of photogenerated electrons leading to their separation from holes. This action aids in the intense production of active superoxide radicals and preserves the recombination of holes. These two potent species have been confirmed to be responsible for the photocatalytic process according to scavengers’ effect. Concerning the reusability, 6%Ni-AgP presents a good stability alongside its excellent photocatalytic activity.

Hyaluronic Acid-Stabilized Fe3O4 Nanoparticles for Promoting In Vivo Magnetic Resonance Imaging of Tumors.

The use of iron oxide (Fe3O4) nanoparticles as novel contrast agents for magnetic resonance imaging (MRI) has attracted great interest due to their high r 2 relaxivity. However, both poor colloidal stability and lack of effective targeting ability have impeded their further expansion in the clinics. Here, we reported the creation of hyaluronic acid (HA)-stabilized Fe3O4 nanoparticles prepared by a hydrothermal co-precipitation method and followed by electrostatic adsorption of HA onto the nanoparticle surface. The water-soluble HA functions not only as a stabilizer but also as a targeting ligand with high affinity for the CD44 receptor overexpressed in many tumors. The resulting HA-stabilized Fe3O4 nanoparticles have an estimated size of sub-20 nm as observed by transmission electron microscopy (TEM) imaging and exhibited long-term colloidal stability in aqueous solution. We found that the nanoparticles are hemocompatible and cytocompatible under certain concentrations. As verified by quantifying the cellular uptake, the Fe3O4@HA nanoparticles were able to target a model cell line (HeLa cells) overexpressing the CD44 receptor through an active pathway. In addition, we showed that the nanoparticles can be used as effective contrast agents for MRI both in vitro in HeLa cells and in vivo in a xenografted HeLa tumor model in rodents. We believe that our findings shed important light on the use of active targeting ligands to improve the contrast of lesion for tumor-specific MRI in the nano-based diagnosis systems.