Mg-Fe Layered Double Hydroxide Research Articles

Synthesis of MgFe Layered Double Hydroxide from Iron-Containing Acidic Residual Solution and Its Adsorption Performance

The paper presents a new method of layered double hydroxide (LDH) synthesis starting from secondary sources, namely acidic residual solutions. The iron content of the acidic solution resulting from the pickling step of the hot-dip galvanizing process make it suitable to be used as an iron precursor in LDH synthesis. Here, Mg4Fe–LDH synthesized through the newly proposed method presented structural and morphological characteristics similar to the properties of layered double hydroxides synthesized from analytical-grade reagents. Moreover, the as-synthesized LDH and its calcined product presented efficient adsorption properties in the removal process of Mo(VI) from aqueous solutions. The adsorption studies are discussed from the equilibrium, kinetic, and thermodynamic points of view. The proposed novel technologies present both economic and environmental protection benefits.

In-situ growth of layered double hydroxide films on biomedical magnesium alloy by transforming metal oxyhydroxide

Layered double hydroxide (LDH) films have been widely used for corrosion protection and medical applications. The most common synthesis methods for in-situ growth of LDH films on magnesium (Mg) alloys are hydrothermal treatment and steam coating. However, both the methods are mainly used for preparing MgAl LDH films and have limitations to in-situ fabricate other Mg-based LDH films which are suitable for biomedical application. Herein, a novel synthesis strategy for in-situ growth of LDH films on Mg alloys is proposed. Firstly, amorphous ferric oxyhydroxide (FeOOH) film was developed on Mg-Nd-Zn-Zr (JDBM) alloy by electrodeposition technique. Then, the as-prepared FeOOH films were transformed into MgFe LDH film via hydrothermal treatment in water. In the LDH formation process, Mg2+ would enter into amorphous FeOOH and replace the Fe3+ quickly to form LDH. The thickness of the LDH films can be easily controlled by adjusting electrodeposition time. Electrochemical tests and cells culture experiments indicated that the as-prepared MgFe LDH films improved corrosion resistance and biocompatibility of JDBM alloy. In addition, MgMn LDH can also be prepared from amorphous manganese oxyhydroxide (MnOOH) via this newly developed two-step method. The present work provides a new strategy for preparation of LDH films on Mg alloys surface.

Layered double hydroxide–loaded biochar as a sorbent for the removal of aquatic phosphorus: behavior and mechanism insights

This study was aimed to enhance the phosphorus (P) sorption capability of biochar through embedding of Mg-Fe layered double hydroxide (LDH) particles within its matrix. The structure, morphology, and surface chemistry of the prepared LDH/biochar composite were investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) analysis. The P sorption behavior of LDH/biochar composite was assessed in comparison with the raw biochar under batch conditions. The effects of initial P concentrations, pH levels, and contact times on P sorption were examined. Results showed that the P sorption on LDH/biochar composite was pH-dependent, and the maximum P sorption was found at the pH range of 2–4. The sorption isotherm and kinetic data were best fitted with the Langmuir and pseudo-second-order models, respectively. The maximum P sorption capacity (Qmax) improved from 1.39 mg g−1 for raw biochar to 17.46 mg g−1 for LDH/biochar composite, respectively. Also, the equilibrium contact time decreased from 8 h for raw biochar to 1 h for LDH/biochar composite, respectively. The sorption process followed electrostatic attraction, ligand exchange, and surface inner-sphere complex formation mechanisms. Overall, the results of the present study revealed that the synthesized LDH/biochar composite can be potentially used as a carbon-based sorbent for the removal of phosphorus from aqueous solutions.

Mg-Fe Layered Double Hydroxides Enhance Surfactin Production in Bacterial Cells

In this study, four additives—montmorillonite, activated carbon, and the layered double hydroxides (LDHs), Mg2Fe–LDH and Mg2Al–LDH—were tested for their ability to promote surfactin production in a Bacillus subtilis ATCC 21332 culture. Among these tested materials, the addition of 4 g/L of the Mg-Fe LDH, which featured an Mg/Fe molar ratio of 2:1, produced the highest surfactin yield of 5280 mg/L. During the time course of B. subtilis cultivation with the added LDH, two phases of cell growth were evident: Growth and decay. In the growth phase, the cells grew slowly and secreted a high amount of surfactin; in the decay phase, the cells degraded rapidly. The production in the presence of the Mg2Fe–LDH had three characteristics: (i) High surfactin production at low biomass, indicating a high specific surfactin yield of 3.19 g/g DCW; (ii) rapid surfactin production within 24 h, inferring remarkably high productivity (4660 mg/L/d); and (iii) a lower carbon source flux to biomass, suggesting an efficient carbon flux to surfactin, giving a high carbon yield of 52.8%. The addition of Mg2Fe–LDH is an effective means of enhancing surfactin production, with many potential applications and future industrial scale-up.

Antimonate adsorption onto Mg-Fe layered double hydroxides in aqueous solutions at different pH values: Coupling surface complexation modeling with solid-state analyses

In this study, the importance of Sb behavior under different pH conditions has been addressed with respect to its stabilization in aqueous solutions using Mg-Fe layered double hydroxides (LDHs). The Sb(V) adsorption onto Mg-Fe LDHs was performed at different initial Sb(V) concentrations and pH values (pH 5.5, 6.5 and 7.5). The removal rate and the maximal adsorbed amount increased with decreasing pH values. Moreover, the surface complexation modeling (SCM) predicted preferable formation of monodentate mononuclear and bidentate binuclear complexes on the Mg-Fe LDH surface. Spectroscopic (X-ray diffraction analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy) and microscopic (scanning electron microscopy and energy-dispersive X-ray spectroscopy) techniques were used to further specify the adsorption mechanisms. The influence of chemical adsorption, surface-induced precipitation of brandholzite Mg[Sb(OH)6]2·6H2O, formation of brandholzite-like phases and/or anion exchange was observed. Moreover, Sb(V) was nonhomogeneously distributed on the Mg-Fe LDH surface at all pH values. The surface complexation modeling supported by solid-state analyses provided a strong tool to investigate the binding arrangements of Sb(V) on the Mg-Fe LDH surface. Such a complex mechanistic/modeling approach has not previously been presented and enables prediction of the Sb(V) adsorption behavior onto Mg-Fe LDHs under different conditions, evaluating their possible use in actual applications.

Fabrication of Fluorescence Turn-off-on Sensor Based on g-C3N4 Quantum Dots and MgFe Layered Double Hydroxide for the Detection of Citrate.

We fabricated a new and selective fluorescent sensor for the detection of citrate by employing g-C3N4 quantum dots (g-CNQDs) and MgFe layered double hydroxide (MgFe-LDH). The g-CNQDs interacted with MgFe-LDH via electrostatic interaction and the fluorescence of g-CNQDs was effectively quenched by MgFe-LDH due to inner filter effect. Upon addition of citrate, the fluorescence of the g-CNQDs was significantly enhanced, arising from the replacement of g-CNQDs by citrate because citrate competed with g-CNQDs to form more stable complexes with MgFe-LDH. Therefore, we developed a "turn-off-on" fluorescence assay method for the detection of citrate. This method enabled the selective detection of citrate with linear range of 0.5-3.0μM and 3.0-10.0μM with a 12.3nM limit of detection. This method exhibited advantages including easy preparation, environmentally friendly process and rapid response toward citrate.

Potential Sustainable Slow-Release Fertilizers Obtained by Mechanochemical Activation of MgAl and MgFe Layered Double Hydroxides and K₂HPO₄.

This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg2Al-CO3 or Mg2Fe-CO3 layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K2HPO4). The effects of LDH thermal treatment on P/K release behavior were investigated. Characterizations of the inorganic composites before and after release experiments combined X-Ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The best release profile (<75% in 28 days and at least 75% release) was obtained for MgAl/K2HPO4 (9 h milling, 2:1 molar ratio, MR). Compared to readily used K2HPO4, milling orthophosphate into LDH matrices decreases its solubility and slows down its release, with 60% and 5.4% release after 168 h for MgAl/K2HPO4 and MgFe/K2HPO4 composites, respectively. Mechanochemical addition of carboxymethylcellulose to the LDH/K2HPO4 composites leads to a noticeable improvement of P release properties.

A novel magnetic biochar/MgFe-layered double hydroxides composite removing Pb2+ from aqueous solution: Isotherms, kinetics and thermodynamics

An absorbent, magnetic biochar supporting MgFe-Layered double hydroxides (MgFe-LDH) composites was synthesized to remove Pb2+ from the aqueous solution. The results of SEM, EDS, XRD, FT-IR, XPS, VSM and BET determinations showed that MgFe-LDH was successfully loaded on the magnetic biochar by hydrothermal synthesis. These characterizations also indicated that the adsorption of Pb2+ resulted from co-precipitation between interlayer anions, surface hydroxyl groups and Pb2+. The isotherms study revealed that the adsorption of Pb2+ on magnetic biochar/MgFe-LDH was well fitted to Langmuir model. The maximum adsorption capacity was 476.25 mg g−1 at 25 °C. Kinetic and thermodynamic studies indicated that the adsorption process was a spontaneous endothermic reaction and limited by chemisorption. Owing to the simple synthesis, superior adsorption capacity, good magnetic properties and cyclic utilization, the magnetic biochar/MgFe-LDH is a promising adsorbent for removing Pb2+ from aqueous solution.

Adsorption of phosphorus by using magnetic Mg-Al-, Zn-Al- and Mg-Fe-layered double hydroxides: comparison studies and adsorption mechanism.

Mg-Al, Zn-Al and Mg-Fe magnetic layered double hydroxide (LDH) adsorbents were synthesized. The adsorption effect and influencing factors of these adsorbents were explored, and the adsorption mechanism of phosphorus was studied with advanced instruments. The results showed that the best adsorption performance was observed when the molar ratio of metals was 3 for the magnetic LDH adsorbents, and the maximum adsorption amount for phosphorus was 74.8, 80.8 and 67.8mg/g for Mg-Al, Zn-Al and Mg-Fe LDHs, respectively. Pseudo-second-order kinetics could be used to describe the adsorption process of phosphorus onto the magnetic LDHs. The adsorption of phosphorus onto the magnetic LDHs was an exothermic process. Lower temperatures were favourable for adsorption, and the adsorption of phosphorus onto the magnetic LDHs was a spontaneous process. When the solid-liquid ratios were 0.10g/L, 0.10g/L and 0.05g/L for Mg-Al, Zn-Al and Mg-Fe magnetic LDHs, respectively, the highest adsorption amount of phosphorus was achieved for each magnetic LDH. The maximum adsorption amount was observed at pH values of 6.0-8.0. The inhibitory effect of HCO3- on the adsorption capacity of phosphorus onto the magnetic LDHs was the strongest at a higher HCO3- concentration level. The relative content of -OH significantly reduced after adsorption of phosphorus by the FTIR analysis, which indicated that the mechanism of phosphorus removal was mainly through the exchange between hydroxyl on the adsorbent surface and phosphorus in water. XPS studies showed that oxygen provided electrons during the adsorption of phosphorus.

Immobilization of layered double hydroxide in poly(vinylidene fluoride)/poly(vinyl alcohol) polymer matrices to synthesize bead-type adsorbents for phosphate removal from natural water

Layered double hydroxide (LDH) has been widely used as an adsorbent to remove contaminants from aqueous solutions. However, LDH in powder form might not be suitable in water and wastewater treatment systems due to low hydraulic conductivity and sludge production. Therefore, it is necessary to synthesize bead-type adsorbents for application in treatment systems. In this study, LDH beads were prepared through immobilization of powdered MgFe LDH in polymer matrices, composed of poly(vinylidene fluoride) and poly(vinyl alcohol). The LDH beads had an average size of 2.4 ± 0.6 mm with a Brunauer-Emmett-Teller (BET) specific surface area of 30.41 m2/g and total pore volume of 0.12 cm3/g. Batch experiments were conducted on the use of the LDH beads for phosphate sorption in stream water (pH = 6.9, ionic strength = 613 μS/cm) collected from the Seoho stream located in Suwon, Korea. Fourier-transform infrared (FTIR) spectrometer and X-ray photoelectron spectroscopy (XPS) were used to analyze the chemical characteristics of the LDH beads before and after phosphate sorption. Phosphate sorption to the LDH beads remained relatively constant at initial pH values of 5–9. The LDH beads could be used repeatedly for phosphate sorption through desorption with a NaOH solution. The equilibrium time for the phosphate sorption was 3 h, whereas the maximum sorption capacity was 2.050 mgP/g. In addition, the phosphate sorption increased with a rise in temperature from 15 to 45 °C. Under dynamic flow conditions (flow rate = 4.9 and 9.8 mL/min; bed depth = 10, 20, and 30 cm; inner diameter of column = 2.5 cm), fixed-bed column experiments were performed to test the applicability of the LDH beads in the phosphate removal from the stream water. The phosphate sorption capacity of the column was quantified to be 1.175 mgP/g at given experimental conditions (bed depth = 30 cm; flow rate = 4.9 mL/min). The performance of fixed-bed columns was quantified by analyzing phosphate breakthrough curves with fixed-bed kinetic sorption models (Bohart-Adams and modified dose-response models). This study demonstrated that the LDH beads could be successfully applied as adsorbents for phosphate removal from natural water.

Sorption of cadmium onto Mg-Fe Layered Double Hydroxide (LDH)-Kiwi branch biochar

ABSTRACTThe Cd(II) adsorption of kiwi biochar functionalized with Mg-Fe (3:1) layered double hydroxides (LDH) was studied. And the biochar was got via liquid-phase deposition, by incorporating Mg-Fe layered double hydroxide (Mg-Fe LDH) particles into kiwi biochar (KB/LDH). The batch of sorption experiments were studied, including adsorption kinetics and isotherm and the effects of pH, ion strength (IS) and co-existing ions. The KB/LDH composite showed a strong sorption ability to Cd(II) in aqueous solutions with the adsorption capacity of 25.6 mg g−1, compared with pristine biochar of 1.78 mg g−1. The adsorption of Cd(II) on KB/LDH composite increased with the decreasing of IS, decreased first and then grew larger with the increase of pH and was observed irrespective of the co-existence of K+, Cl− and NO3−. To sum up, the KB/LDH can be potentially used as an alternative adsorbent to amend the water and soil contaminated by Cd(II).

Facile fabrication of the polyaniline/layered double hydroxide nanosheet composite for supercapacitors

To overcome the structural instability of polyaniline (PANI) due to repeated volumetric swelling and shrinking during charge/discharge process, the LDH/PANI composite was designed and prepared via the assembly of organic PANI and 2D host nanosheets from the MgFe layered double hydroxide (MgFe-LDH) through incorporation of PANI between the nanosheets gap using in situ polymerization. Owing to the combined advantages of conducting PANI and 2D nanosheets, the LDH/PANI composite exhibited excellent supercapacitive performance, including low resistance, high specific capacitance, good charge/discharge stability and long-term cycling life, which greatly improved faradaic redox reaction and mass transfer. As electrode material for supercapacitors, the LDH/PANI composite showed a maximum specific capacitance of 592.5 F·g−1 at a current density of 2 A·g−1, and achieved remarkable capacitance retentions of 87% after 500 cycles. The LDH/PANI material may be a potential economical alternative electrode material for supercapacitors.

Stability and stabilizing efficiency of Mg-Fe layered double hydroxides and mixed oxides in aqueous solutions and soils with elevated As(V), Pb(II) and Zn(II) contents

Although the mechanisms of metal(loid) removal from aqueous solutions using LDHs (layered double hydroxides) and mixed oxides (thermally treated LDHs; CLDHs) have been studied, research dealing with their stability, stabilizing efficiency and remediation potential for contaminated soils remains scarce. We present a complex study investigating the stabilizing efficiency of Mg-Fe LDHs and CLDHs at different conditions, including aqueous solutions and real soils with highly elevated As(V), Pb(II) and Zn(II) concentrations. All studied materials showed excellent (ad)sorption efficiency for As(V), Pb(II) and Zn(II) in aqueous solutions. Additionally, the reconstruction ability of CLDHs at different conditions that could improve their adsorption properties was also evaluated, and the dependence on time, pH and the concentrations of metal(loid)s was shown. In general, CLDHs showed higher stability and stabilizing efficiency in aqueous and soil solutions; however, LDHs were more efficient in contaminated soils. Furthermore, solid state analyses coupled with geochemical modeling showed the formation of new phases corresponding to Mg‑carbonates/silicates on the surfaces of LDH/CLDH after their incubation in soils. Both LDHs and CLDHs significantly decreased the bioavailable/labile fraction of As(V) and Zn(II) in the studied soils. In general, our work shows Mg-Fe LDHs and CLDHs as prospective materials for water and soil remediation.

Hierarchical MgFe-layered double hydroxide microsphere/graphene composite for simultaneous electrochemical determination of trace Pb(II) and Cd(II)

Heavy metal contamination has been demonstrated to possess the severe threats toward the whole ecosystems and public security even at trace levels. Therefore, it is essential to exploit an ultrasensitive technique to determine the levels of heavy metal ions. In this work, hierarchical MgFe-layered double hydroxide (MgFe-LDH) microspheres have been successfully immobilized on the graphene nanosheets surface via a facile one-step hydrothermal route. Benefiting from the synergistic effects associated with high specific surface area, strong affinity of hierarchical MgFe-LDH architecture toward heavy metal ions, good electrical conductivity and effective electron transfer efficiency of graphene, the resulting composite (denoted as MgFe-LDH/graphene) is explored as an electrochemical sensor for simultaneous detection of Pb(II) and Cd(II) in aqueous medium. As a consequence, MgFe-LDH/graphene modified electrode exhibits low detection limit of 5.9 nM for Cd(II) and 2.7 nM for Pb(II), which are dramatically lower than the respective values of 3 ppb (27 nM) and 10 ppb (48 nM) in domestic water permitted by the World Health Organization (WHO). Meaningfully, the proposed electrochemical sensor shows specific recognition capability to Pb(II) and Cd(II), excellent reproducibility in repetitive measurements as well as feasibility in real water analysis.

The Adsorption of Dextranase onto Mg/Fe-Layered Double Hydroxide: Insight into the Immobilization.

We report the adsorption of dextranase on a Mg/Fe-layered double hydroxide (Mg/Fe-LDH). We focused the effects of different buffers, pH, and amino acids. The Mg/Fe-LDH was synthesized, and adsorption experiments were performed to investigate the effects. The maximum adsorption occurred in pH 7.0 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer, and the maximum dextranase adsorption uptake was 1.38 mg/g (416.67 U/mg); histidine and phenylalanine could affect the adsorption. A histidine tag could be added to the protein to increase the adsorption significantly. The performance features and mechanism were investigated with X-ray diffraction patterns (XRD) and Fourier transform infrared spectra (FTIR). The protein could affect the crystal structure of LDH, and the enzyme was adsorbed on the LDH surface. The main interactions between the protein and LDH were electrostatic and hydrophobic. Histidine and phenylalanine could significantly affect the adsorption. The hexagonal morphology of LDH was not affected after adsorption.

One-pot synthesis of layered double hydroxide hollow nanospheres with ultrafast removal efficiency for heavy metal ions and organic contaminants

Herein, Mg/Fe layered double hydroxide (MF-LDH) hollow nanospheres were successfully prepared by a one-step thermal method. After the thermal treatment of MF-LDH nanospheres at 400 °C, the MF-LDH was converted into the corresponding oxide, Mg/Fe layered double oxide (MF-LDO), which maintained the hollow nanosphere structure. The MF-LDO hollow nanospheres exhibited excellent adsorption efficiency for both As(V) and Cr(VI), showing 99% removal within 5 min and providing maximum removal capacities of 178.6 mg g−1 [As(VI)] and 148.7 mg g−1 [Cr(VI)]. Moreover, it met the maximum contaminant level requirements recommended by World Health Organization (WHO); 10 ppm for As(V) and 50 ppm for Cr(VI) in 10 and 20 min, respectively. Furthermore, Au nanoparticles were successfully introduced in the MF-LDO hollow nanospheres, and the products showed a conversion rate of 100% for the reduction of 4-nitrophenol into 4-aminophenol within 5 min. It is believed that these excellent and versatile abilities integrated with a facile synthetic strategy will facilitate the practical application of this material in cost-effective wastewater purification.

Brucite-driven CO2 uptake in serpentinized dunites (Ligurian Ophiolites, Montecastelli, Tuscany)

Understanding the mechanism of serpentinite weathering at low temperature – that involves carbonate formation – has become increasingly important because it represents an analog study for a cost-efficient carbon disposal strategy (i.e. carbon mineralization technology or mineral Carbon dioxide Capture and Storage, CCS).At Montecastelli (Tuscany, Italy), on-going spontaneous mineral CO2 sequestration is enhanced by brucite-rich serpentinized dunites. The dunites are embedded in brucite-free serpentinized harzburgites that belong to the ophiolitic Ligurian Units (Northern Apennine thrust-fold belt). Two main serpentinization events produced two distinct mineral assemblages in the reactive dunite bodies. The first assemblage consists of low-T pseudomorphic, mesh-textured serpentine, Fe-rich brucite (up to 20mol.% Fe(OH)2) and minor magnetite. This was overprinted by a non-pseudomorphic, relatively high-T assemblage consisting of serpentine, Fe-poor brucite (ca. 4mol% Fe(OH)2) and abundant magnetite. The harzburgite host rock developed a brucite-free paragenesis made of serpentine and magnetite.Present-day interaction of serpentinized dunites with slightly acidic and oxidizing meteoric water, enhances brucite dissolution and leads to precipitation of both Mg-Fe layered double hydroxides (coalingite-pyroaurite, LDHs) and hydrous Mg carbonates (hydromagnesite and nesquehonite). In contrast, the brucite-free serpentinized harzburgites are not affected by the carbonation process.In the serpentinized dunites, different carbonate minerals form depending on brucite composition (Fe-rich vs Fe-poor). Reactions in serpentinized dunites containing Fe-rich brucite produce a carbonate assemblage dominated by LDHs and minor amount of hydromagnesite. Serpentinites with a Fe-poor brucite assemblage contain large amounts of hydromagnesite and minor LDHs. Efficiency of CO2 mineral sequestration is different in the two cases owing to the distinct carbon content of LDHs (ca. 1.5wt.%) and hydromagnesite (ca. 10wt.%).Here, for the first time, we link the mineral composition of serpentinized ultramafic rocks to carbonate formation, concluding that Fe-poor brucite maximizes the mineral CCS efficiency.

Synthesis of Mg-Fe layered double hydroxides and its application as catalyst for Friedel-Crafts benzoylation

Mg-Fe layered double hydroxides were synthesized by the coprecipitation method with different of Mg/Fe ratio (2/1, 3/1 and 4/1) and then were thermally transformed into mixed metal oxides. The obtained materials before and after the calcination at 450 oC were characterized by X-ray diffraction (XRD), SEM, BET, TGA, ICP. The samples were used as a catalyst for Friedel-Crafts benzoylation reactions. The catalyst can be easily separated and recycled compared to the traditional one.

High efficiency and selectivity of MgFe-LDH modified wheat-straw biochar in the removal of nitrate from aqueous solutions

Mg–Fe layered double hydroxide (MgFe-LDH) particles were incorporated into wheat-straw biochar by liquid-phase deposition. The obtained biochar/MgFe-LDH composite was used to remove nitrate from aqueous solutions. X-ray diffraction patterns demonstrated that LDH particles were successfully deposited onto the carbon surface within the biochar matrix. Adsorption kinetic and isotherm studies and the effects of co-existing anions and adsorbents dosages were investigated using laboratory batch sorption experiments. The biochar/MgFe-LDH composite showed a strong sorption ability to nitrate in aqueous solutions with the Langmuir maximum adsorption capacity of 24.8mg/g. A high selectivity for nitrate of the biochar/MgFe-LDH composite was also observed irrespective of the co-existence of sulfate and phosphate. The biochar/MgFe-LDH composite can thus be potentially used as an alternative adsorbent for the treatment of nitrate-contaminated waters as well as a soil amendment for the reduction of soil nitrate leaching.

Biocompatibility and intradiscal application of a thermoreversible celecoxib-loaded poly-N-isopropylacrylamide MgFe-layered double hydroxide hydrogel in a canine model.

IntroductionChronic low back pain due to intervertebral disc (IVD) degeneration is associated with increased levels of inflammatory mediators. Current medical treatment consists of oral anti-inflammatory drugs to alleviate pain. In this study, the efficacy and safety of a novel thermoreversible poly-N-isopropylacrylamide MgFe-layered double hydroxide (pNIPAAM MgFe-LDH) hydrogel was evaluated for intradiscal controlled delivery of the selective cyclooxygenase (COX) 2 inhibitor and anti-inflammatory drug celecoxib (CXB).MethodsDegradation, release behavior, and the ability of a CXB-loaded pNIPAAM MgFe-LDH hydrogel to suppress prostaglandin E2 (PGE2) levels in a controlled manner in the presence of a proinflammatory stimulus (TNF-α) were evaluated in vitro. Biocompatibility was evaluated histologically after subcutaneous injection in mice. Safety of intradiscal application of the loaded and unloaded hydrogels was studied in a canine model of spontaneous mild IVD degeneration by histological, biomolecular, and biochemical evaluation. After the hydrogel was shown to be biocompatible and safe, an in vivo dose–response study was performed in order to determine safety and efficacy of the pNIPAAM MgFe-LDH hydrogel for intradiscal controlled delivery of CXB.ResultsCXB release correlated to hydrogel degradation in vitro. Furthermore, controlled release from CXB-loaded hydrogels was demonstrated to suppress PGE2 levels in the presence of TNF-α. The hydrogel was shown to exhibit a good biocompatibility upon subcutaneous injection in mice. Upon intradiscal injection in a canine model, the hydrogel exhibited excellent biocompatibility based on histological evaluation of the treated IVDs. Gene expression and biochemical analyses supported the finding that no substantial negative effects of the hydrogel were observed. Safety of application was further confirmed by the absence of clinical symptoms, IVD herniation or progression of degeneration. Controlled release of CXB resulted in a nonsignificant maximal inhibition (approximately 35 %) of PGE2 levels in the mildly degenerated canine IVDs.ConclusionsIn conclusion, this study showed biocompatibility and safe intradiscal application of an MgFe LDH-pNIPAAM hydrogel. Controlled release of CXB resulted in only limited inhibition of PGE2 in this model with mild IVD degeneration, and further studies should concentrate on application of controlled release from this type of hydrogel in animal models with more severe IVD degeneration.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0727-x) contains supplementary material, which is available to authorized users.