Layered Double Hydroxide Nanohybrids Research Articles

MOF-derived Co-Al layered double hydroxide modified rice husk biochar nanohybrid for efficient removal of Cu (II) from wastewater

In this study, biochar-derived rice husk (RHB) was modified with Co-Al layered double hydroxide (LDH) derived from Co-based metal-organic framework (ZIF-67) through hydrothermal method to prepare RHB/ZIF-67-derived Co-Al LDH nanohybrid as adsorbent for efficient removal of copper (II) ions from aqueous medium. The nanohybrid was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, and N2 adorption-desorption. Atomic absorption spectroscopy (AAS) was employed to analyze the concentration of Cu (II) in aqueous solution. In order to investigate the effect of contact time, pH of solution, and adsorbent dose on the removal performance of RHB/ZIF-67-derived Co-Al LDH nanohybrid, batch experimental studies were conducted. The surface adsorption isotherm is well fitted to Langmuir model, and the adsorption mechanism follows the pseudo-second-order kinetic model. In addition, based on the central composite design in the response surface method, the optimal conditions for adsorbent dose, time, pH and initial concentration of Cu (II) are obtained as 2 mg, 3 min, 7 and 50 ppm respectively. In optimal conditions, the nanohybrid shows many advantages including the high removal percent (99.71 %) for Cu (II) ions, excellent adsorption capacity of 1377.94 mg g−1, the ability to reuse for five times, low cost, and compatibility with the environment. The combined properties of RHB and ZIF-67-derived Co-Al LDH provide a large surface area of 849.44 m2 g−1, which increases the contact surface of adsorbent with Cu (II) ions and endows great adsorption performance even in complex environments.

Efficient Protection of Paper‐Based Cultural Relics via In Situ Synthesis of Carbon Dots/Layered Double Hydroxide

AbstractPaper‐based cultural relics are of great value and have been facing irreversible damage caused by multiple factors, among which acid hydrolysis and ultraviolet photodegradation are the main processes leading to paper deterioration. Paper protection highly relies on a limited range of materials with single functions, and the design of new materials that ensure long‐term safety and efficiency by simultaneously addressing the issues of acidification and UV degradation in paper is highly desired. In this study, the introduction of carbon dots (CDs)‐enhanced layered double hydroxides (LDH) 0D/2D nanohybrids (CDs/Mg‐Al LDH)  is proposed as novel dual‐functional materials for paper protection against UV degradation and acidification. Through a CDs‐assisted in situ growth strategy, CDs/Mg‐Al LDH with ultrathin thickness (≈9.1 nm) and CDs‐intercalated structure are achieved. The CDs/Mg‐Al LDH nanohybrids demonstrate high dispersibility, strong UV absorption, and remarkable photostability, resulting in protected‐paper with decelerated acidification, oxidation, and yellowing degradation processes under both accelerated UV‐aging and dry‐heat conditions. Additionally, the protected‐paper can emit uniform blue light under 365 nm UV excitation allows for easy identification of the distributed CDs/Mg‐Al LDH within the paper, marking a unique and practical feature. This research paces a new direction for the protection of paper‐based relics with emerging carbon dots‐based 0D/2D nanomaterials.

Synthesis of Ammonium-Polyphosphate-Modified Layered Double Hydroxide Nanohybrid via a Siloxane Polycondensation Method and Its Use as an Environmentally Friendly Flame Retardant Nanofiller in Polypropylene

Synthesis of Ammonium-Polyphosphate-Modified Layered Double Hydroxide Nanohybrid via a Siloxane Polycondensation Method and Its Use as an Environmentally Friendly Flame Retardant Nanofiller in Polypropylene

Improving Photoluminescence Emissions and Photostability of Dye/MgAl‐Layered Double Hydroxide Nanohybrids

AbstractThe purpose of this study was the preparation of layered double hydroxide (LDH) ‐based nanohybrids with improved photoluminescence emission and high photostability. The anion exchange‐based microwave method was applied for the intercalation of mordant orange 1 into MgAl‐LDH. The prepared organic‐inorganic nanohybrid was confirmed by X‐ray diffraction, thermal gravimetric analysis (TGA), inductively coupled plasma spectrometry (ICP), and infrared spectra (FT‐IR). Also, the morphology of the obtained sample was investigated using the field emission‐scanning electron microscopy (FE‐SEM) method. In the MgAl‐LDH interlayer space, a tilted orientation and bilayer arrangement were predicted for the mordant orange 1 anions. Compared with the pure mordant orange 1, the MgAl‐LDH/mordant orange 1‐MA (prepared using the microwave‐based anion exchange method) has improved photoluminescence emission with high Photostability. These findings supply a new approach for designing photoluminescence materials that potentially apply to optical devices with high Photostability.

Engineering the Morphostructural Properties and Drug Loading Degree of Organic-Inorganic Fluorouracil-MgAl LDH Nanohybrids by Rational Control of Hydrothermal Treatment.

Layered double hydroxides (LDHs) or hydrotalcite-like compounds have attracted great attention for the delivery of anticancer drugs due to their 2D structure, exhibiting a high surface-to-volume ratio and a high chemical versatility. The drug is protected between the layers from which it is slowly released, thus increasing the therapeutic effect and minimizing the side effects associated to nonspecific targeting. This work aimed to design LDHs with Mg and Al (molar ratio of 2/1) in brucite-like layers, which retained fluorouracil (5-FU; 5-FU/Al = 1, molar ratio) in the interlayer gallery as the layers grow during the co-precipitation step of the synthesis. To rationally control the physicochemical properties, particularly the size of the crystallites, the aging step following the co-precipitation was performed under carefully controlled conditions by changing the time and temperature (i.e., 25 °C for 16 h, 100 °C for 16 h, and 120 °C for 24 h). The results revealed the achievement of the control of the size of the crystals, which are gathered in three different agglomeration systems, from tight to loose, as well as the loading degree of the drug in the final organic-inorganic hybrid nanomaterials. The role played by the factors and parameters affecting the drug-controlled release was highlighted by assessing the release behavior of 5-FU by changing the pH, solid mass/volume ratio, and ionic strength. The results showed a pH-dependent behavior but not necessarily in a direct proportionality. After a certain limit, the mass of the solid diminishes the rate of release, whereas the ionic strength is essential for the payload discharge.

Biodegradable layered double hydroxide based polymeric films for sustainable food packaging applications

In this study, solution casting was used to create hybrid biodegradable films that were made of Polycaprolactone (PCL) and Zn-Al layered double hydroxide (LDH) intercalated with salicylate (SA) (P-L-S nanocomposites). P-L-S (5%) nanocomposite film has a water vapor transmission rate of just 212.5 g/m2/day at 85% relative humidity, which is 55.5% less than that of pure PCL film. This outstanding performance of the water vapor barrier is mostly due to the convoluted action of 2D LDH nanohybrids. In addition, the hydroxyl groups of LDH create hydrogen bonds with the entering water molecules, further preventing the passage of water vapor. The aforementioned nanocomposite showed excellent biodegradability by decomposing by over 75% in just 90 days. More than 94% inhibition of E. coli and S. aureus in 30 min, which is a promising finding when compared to the existing literature, was demonstrated as a result of a controlled release of salicylate (intercalated between the inorganic lamella) to the medium. The P-L-S (5%) nanocomposite additionally showed the best radical scavenging ability against DPPH. (82%) in only 72 h. The aforementioned characteristics point to the possible uses for P-L-S nanocomposite films in the domain of biodegradable packaging.

Flower-like Layered NiCu-LDH/MXene Nanocomposites as an Anodic Material for Electrocatalytic Oxidation of Methanol

Direct methanol fuel cell (DMFC) technology has grabbed much attention from researchers worldwide in the realm of green and renewable energy-generating technologies. Practical applications of DMFCs are marked by the development of highly active, efficient, economical, and long-lasting anode catalysts. Layered double hydroxide (LDH) nanohybrids are found to be efficient electrode materials for methanol oxidation. In this study, we synthesized NiCu-LDH/MXene nanocomposites (NCMs) and investigated their electrochemical performance for methanol oxidation. The formation of NCM was verified through field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and X-ray photoemission spectroscopy (XPS) analyses. The cyclic voltammetry, chronoamperometry, and electron impedance spectroscopy techniques were carried out to assess the electrocatalytic ability of the methanol oxidation reaction. The incorporation of MXene enhanced the methanol oxidation 2-fold times higher than NiCu-LDH. NCM-45 exhibited high peak current density (86.9 mA cm-2), enhanced electrochemical active surface area (7.625 cm2), and long-term stability (77.8% retention after 500 cycles). The superior performance of NCM can be attributed to the synergistic effect between Ni and Cu and, further, the electronic coupling between LDH and MXene. Based on the results, NCM nanocomposite is an efficient anodic material for the electrocatalytic oxidation of methanol. This study will open the door for the development of various LDH/MXene nanocomposite electrode materials for the application of direct methanol fuel cells.

Investigation and multiscale modeling of PVA/SA coated poly lactic acid scaffold containing curcumin loaded layered double hydroxide nanohybrids.

Applying hydrophilic coatings on polymeric nanofibers combined with layered double hydroxide (LDH) not only enhances the efficiency of drug delivery systems but also increases cell adhesion. This work aimed to prepare poly(vinyl alcohol)/sodium alginate (PVA/SA) (2/1)-coated poly(lactic acid) (PLA) nanofibers containing curcumin-loaded layered double hydroxide (LDH) and to investigate their drug release and mechanical properties and their biocompatibility. The optimum PLA nanofibrous sample was considered to be that based on 3 wt% of curcumin-loaded LDH (PLA-3%LDH) with a drug encapsulation efficiency of ∼18% in which a minimum average nanofiber diameter of ∼476 nm along with a high tensile strength of 3.00 MPa were obtained. In the next step, a PVA/SA (2/1) layer was coated on the PLA-3%LDH; as a result, the hydrophilicity of the sample was improved and the elongation at break was decreased remarkably. In this regard the cell viability reached 80% for the coated PLA. Moreover, the formation of a layer of (PVA/SA) on the PLA nanofibers lowered the burst release and resulted in a more sustained drug release, which is a vital feature in dermal applications. A multiscale modeling method was applied for simulation of the mechanical properties of the composite scaffold and the results showed that this method can predict the data with 83% accuracy. The results of this study indicate that the formation of a layer of PVA/SA (2/1) has a significant effect on hydrophilicity and consequently improves cell adhesion and proliferation.

Biofunctional Layered Double Hydroxide Nanohybrids for Cancer Therapy.

Layered double hydroxides (LDHs) with two-dimensional nanostructure are inorganic materials that have attractive advantages such as biocompatibility, facile preparation, and high drug loading capacity for therapeutic bioapplications. Since the intercalation chemistry of DNA molecules into the LDH materials were reported, various LDH nanohybrids have been developed for biomedical drug delivery system. For these reasons, LDHs hybridized with numerous therapeutic agents have a significant role in cancer imaging and therapy with targeting functions. In this review, we summarized the recent advances in the preparation of LDH nanohybrids for cancer therapeutic strategies including gene therapy, chemotherapy, immunotherapy, and combination therapy.

Bio-Inorganic Layered Double Hydroxide Nanohybrids in Photochemotherapy: A Mini Review.

Clay-based bio-inorganic nanohybrids, such as layered double hydroxides (LDH), have been extensively researched in the various fields of biomedicine, particularly for drug delivery and bio-imaging applications. Recent trends indicate that such two-dimensional LDH can be hybridized with a variety of photo-active biomolecules to selectively achieve anti-cancer benefits through numerous photo/chemotherapies (PCT), including photothermal therapy, photodynamic therapy, and magnetic hyperthermia, a combination of therapies to achieve the best treatment regimen for patients that cannot be treated either by surgery or radiation alone. Among the novel two-dimensional clay-based bio-inorganic nanohybrids, LDH could enhance the photo-stability and drug release controllability of the PCT agents, which would, in turn, improve the overall phototherapeutic performance. This review article highlights the most recent advances in LDH-based two-dimensional clay-bio-inorganic nanohybrids for the aforementioned applications.

Anti-microbial Nanohybrids Based on Naturally Derived Citric Acid Intercalated Layered Double Hydroxides

Currently, there is an increased demand for advanced food packages, which can significantly increase the shelf life of food items. In the current context, it is envisaged that nanotechnology has the potential to address stability, toxicity, shelf-life, and low-cost issues of antimicrobials associated with the packaging industry. Antimicrobial nanocomposite systems are believed to be more efficient than their microscale counterparts due to the high surface area to volume ratio and quantum mechanical involvement in deciding their properties. As a result of high surface area, they are able to attach more copies of microbial molecules and cells, thus reducing the quantity of material required while significantly improving their activity. This study focuses on the development of slow-release antimicrobial material based on natural citrate (α-hydroxycitrate) intercalated layered double hydroxide (LDH) nanohybrid. Natural citrate ions available in Citrus aurantifolia (lime) were extracted by a simple chemical method and intercalated into Mg-Al-Layered Double Hydroxide following a one-step co-precipitation method. Successful intercalation of the citrate ion was confirmed by powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopic analysis. Release kinetics of resulted nanohybrid was studied and compared using different release kinetic models. Antimicrobial properties of this novel nanohybrid were confirmed against two common food pathogens, Colletotrichum gloeosporioides and Saccharomyces cerevisiae, and the results were compared against sodium benzoate, which is the commonly used commercial antimicrobial agent in the food industry. Successful intercalation of natural citrate ions into LDH and its activity against the tested microbes show the potential of using it as a slow-release nanohybrid material in many food-related applications.
 
 Keywords: Layered Double Hydroxide, α-Hydroxycitrate, Natural, Safe, Lime Extract, Slow Release, Antimicrobial

Mg-LDH Nanoclays Intercalated Fennel and Green Tea Active Ingredient: Field and Laboratory Evaluation of Insecticidal Activities against Culex pipiens and Their Non-Target Organisms.

(1) Background: Mosquito control with essential oils is a growing demand. This work evaluated the novel larvicidal and adulticidal activity of fennel and green tea oils and their Layered double hydroxides (LDHs) nanohybrid against Culex pipiens (Cx. pipiens) in both laboratory and field conditions and evaluated their effect against non-target organisms; (2) Methods: Two types of nanoclays, MgAl-LDH and NiAl-LDH were synthesized and characterized using PXRD, TEM and SEM, whereas their elemental analysis was accomplished by SEM-EDX; (3) Results: Mg and Ni LDHs were synthesized by the co-precipitation method. The adsorption and desorption of active ingredients were conducted using LC MS/MS, with reference to the SEM-EXD analysis. The desorption process of MgAl-LDH intercalated green tea oil was conducted using ethanol, and reveled significant peaks related to polyphenols and flavonoids like Vanillin, Catechin, Daidzein, Ellagic acid, Naringenin, Myricetin and Syringic acid with concentrations of 0.76, 0.73, 0.67, 0.59, 0.52, 0.44 and 0.42 μg/g, respectively. The larvicidal LC50 values of fennel oil, Mg-LDH-F, and Ni-LDH-F were 843.88, 451.95, 550.12 ppm, respectively, whereas the corresponding values of green tea were 938.93, 530.46, and 769.94 ppm. The larval reduction percentage of fennel oil and Mg-LDH-F reached 90.1 and 96.2%, 24 h PT and their persistence reached five and seven days PT, respectively. The reduction percentage of green tea oil and Mg-LDH-GT reached 88.00 and 92.01%, 24 h PT and their persistence reached five and six days PT, respectively. Against adults, Mg-LDH-GT and Ni-LDH-GT were less effective than green tea oil as their LC95 values were 5.45, 25.90, and 35.39%, respectively. The reduction in adult density PT with fennel oil, Mg-LDH-F, green tea oil, and Mg-LDH-GT reached 83.1, 100, 77.0, and 99.0%, respectively, 24 h PT and were effective for three days. Mg-LDH-GT and Mg-LDH-F increased the predation Cybister tripunctatus (71% and 69%), respectively; (4) Conclusions: For the first time, Mg-LDH-GT and Mg-LDH-F was the best system loaded with relatively good desorption release to its active ingredients and significantly affected Cx. pipiens larvae and adults in both laboratory and field circumstances, and it could be included in mosquito control.

Facile and fast preparation of layered double hydroxide as a nanocarrier for ascorbic acid under ultrasonic irradiation.

Background and purpose:Layered double hydroxides (LDHs) as inorganic materials are being used in controlled release and drug delivery systems. These materials are more stable than conventional drug carriers. In this investigation, Mg/Al-ascorbic acid (ASA) LDH nanohybrid was synthesized by ultrasonic-assisted co-deposition techniques.Experimental approach:In this study, Mg/Al-LDH to adsorption of ASA anions from the alkaline solution was assembled by a facile coprecipitation technique. During this process, ultrasonic irradiation was used to increase the rate of ion exchange between LDH and ASA. The intercalated-layered structure was characterized by FT-IR spectroscopy, XRD, thermogravimetric analysis, field emission SEM, and TEM. ASA releasing from Mg/Al-ASA LDH nanohybrid was carried out in incubation sodium carbonate solution (0.5 M) at 35 °C using UV-Vis absorbance analysis at λ = 265 nmFindings/Results:The used techniques confirmed the structure of Mg/Al-LDH and indicated successful intercalation of ASA into the interlayer galleries of the LDH host. The obtained results also have shown that Mg/Al-ASA LDH nanohybrid was generated with an average diameter size of 25 nm and narrow size distribution. Analysis of the release profiles using several kinetic models suggested that the first-order rate model is the most appropriate for describing the release of ASA from Mg/Al-LDH which means the amount of drug released is proportional to the amount of remaining drug in the matrix. Thus, the amount of activity released tends to decrease in function of time.Conclusion and implications:The results showed that LDHs are good host materials to preserve the biomolecule and modify its release rate and bioavailability.

Bi-directional regulation functions of lanthanum-substituted layered double hydroxide nanohybrid scaffolds via activating osteogenesis and inhibiting osteoclastogenesis for osteoporotic bone regeneration.

Rationale: Osteoporotic patients suffer symptoms of excessive osteoclastogenesis and impaired osteogenesis, resulting in a great challenge to treat osteoporosis-related bone defects. Based on the positive effect of rare earth elements on bone metabolism and bone regeneration, we try to prove the hypothesis that the La3+ dopants in lanthanum-substituted MgAl layered double hydroxide (La-LDH) nanohybrid scaffolds simultaneously activate osteogenesis and inhibit osteoclastogenesis.Methods: A freeze-drying technology was employed to construct La-LDH nanohybrid scaffolds. The in vitro osteogenic and anti-osteoclastogenic activities of La-LDH nanohybrid scaffolds were evaluated by using ovariectomized rat bone marrow stromal cells (rBMSCs-OVX) and bone marrow-derived macrophages (BMMs) as cell models. The in vivo bone regeneration ability of the scaffolds was investigated by using critical-size calvarial bone defect model of OVX rats.Results: La-LDH nanohybrid scaffolds exhibited three-dimensional macroporous structure, and La-LDH nanoplates arranged perpendicularly on chitosan organic matrix. The La3+ dopants in the scaffolds promote proliferation and osteogenic differentiation of rBMSCs-OVX by activating Wnt/β-catenin pathway, leading to high expression of ALP, Runx-2, COL-1 and OCN genes. Moreover, La-LDH scaffolds significantly suppressed RANKL-induced osteoclastogenesis by inhibiting NF-κB signaling pathway. As compared with the scaffolds without La3+ dopants, La-LDH scaffolds provided more favourable microenvironment to induce new bone in-growth along macroporous channels.Conclusion: La-LDH nanohybrid scaffolds possessed the bi-directional regulation functions on osteogenesis and osteoclastogenesis for osteoporotic bone regeneration. The modification of La3+ dopants in bone scaffolds provides a novel strategy for osteoporosis-related bone defect healing.

Charge Reversion Simultaneously Enhances Tumor Accumulation and Cell Uptake of Layered Double Hydroxide Nanohybrids for Effective Imaging and Therapy

Nanotheranostics have been actively sought in precision nanomedicine in recent years. However, insufficient tumor accumulation and limited cell uptake often impede the nanotheranostic efficacy. Herein, pH-sensitive charge-reversible polymer-coated layered double hydroxide (LDH) nanohybrids are devised to possess long circulation in blood but reserve surface charges in the weakly acidic tumor tissue to re-expose therapeutic LDH nanoparticles for enhanced tumor accumulation and cell uptake. In vitro experimental data demonstrate that charge-reversible nanohybrids mitigate the cell uptake in physiological conditions (pH 7.4), but remarkably facilitate internalization by tumor cells after charge reversion in the weakly acidic environment (pH 6.8). More significantly, about 6.0% of injected charge-reversible nanohybrids accumulate in the tumor tissue at 24 h post injection, far higher than the average accumulation (0.7%) reported elsewhere for nanoparticles. This high tumor accumulation clearly shows the tumor tissues in T1 -weighted magnetic resonance imaging. As a consequence, >95% inhibition of tumor growth in the B16F0-bearing mouse model is achieved via only one treatment combining RNAi and photothermal therapy under very mild irradiation (808 nm laser, 0.3 W cm-2 for 180 s). The current research thus demonstrates a new strategy to functionalize nanoparticles and simultaneously enhance their tumor accumulation and cell internalization for effective cancer theranostics.

Bone tissue engineering electrospun scaffolds based on layered double hydroxides with the ability to release vitamin D3: Fabrication, characterization and in vitro study

Bone tissue engineered scaffolds can improve and accelerate the tissue regeneration alongside controlled release of drugs and signaling molecules while providing a suitable condition for cell adhesion and, proliferation. The current study involves the fabrication of Poly (ɛ-caprolactone) (PCL) electrospun scaffolds enriched with vitamin D3 (VD3)-loaded layered double hydroxides (LDHs) nanohybrid, in different concentrations. Characterizations confirmed successful synthesis of LDH and formation of crystalline planes and intercalation of VD3 in LDH with 65% encapsulation efficiency. Addition of low concentrations of LDHs nanohybrid to PCL scaffold led to a decrease in the fiber diameter; however, an increase in the surface roughness was observed at higher concentrations. Mechanical properties and porosity of the scaffolds were also evaluated and the results showed a decrease in elongation modulus in nanohybrid enriched scaffolds and no significant differences in porosity percentage was observed. Studies on bioactivity of scaffolds subjected to simulated body fluid (10 X SBF) indicated that the VD3 encouraged the formation of apatite-like crystals in vitro. Furthermore, the degradation rate of scaffolds increased due to the addition of nanohybrid. The cumulative release of VD3 showed the same pattern for all scaffolds through the diffusion as the main controlling mechanism of release. In vitro biological responses of the scaffolds were studied using MG-63 cell lines culture. The results indicated that nanohybrid containing scaffolds could highly support cell adhesion and proliferation. Likewise, alkaline phosphatase activity as an indicator of osteoconductivity for scaffolds showed no significant differences between nanohybrid containing and pure PCL scaffolds (p > .05). The results confirmed the potential of VD3-loaded LDH/PCL electrospun scaffolds for bone tissue engineering.

Functional Layered Double Hydroxide Nanohybrids for Biomedical Imaging.

Biomedical investigations using layered double hydroxide (LDH) nanoparticles have attracted tremendous attentions due to their advantages such as biocompatibility, variable-chemical compositions, anion-exchange capacity, host–guest interactions, and crystallization-dissolution characters. Bio-imaging becomes more and more important since it allows theranostics to combine therapy and diagnosis, which is a concept of next-generation medicine. Based on the unique features mentioned above, LDHs create novel opportunities for bio-imaging and simultaneous therapy with LDHs-based nanohybrids. This review aims to explore the recent advances in multifunctional LDH nanohybrids ranging from synthesis to practical applications for various bio-imaging with therapeutic functions. Furthermore, their potential both as diagnostic agents and drug delivery carriers will be discussed with the improvement in noninvasive bio-imaging techniques.

Hybrid layered double hydroxides-curcumin thin films deposited via Matrix Assisted Pulsed Laser Evaporation-MAPLE with photoluminescence properties

Curcumin (CR) is a natural compound with a well-known antioxidant and therapeutic activity. Its stability may be enhanced when incorporated in different matrices as a layered double hydroxides (LDH) matrix. Curcumin intercalated layered double hydroxide nanohybrid is a potential drug delivery system for effective photodynamic therapy in human breast cancer or skin cancer.The synthesis of the hybrid LDH-CR powder implies the dissolution of CR in water or in another organic solvent which is miscible with water. Since the solubility of curcumin in water is very weak, the aim of this study is to investigate the effect of the solvent employed for its dissolution on the structural and physico-chemical-photoluminescent properties of the resulting hybrid materials. Four powders of curcumin (CR)-containing Mg2.5Al-LDH hybrids (Mg/Al molar ratio of 2.5) were prepared by co-precipitation (P) and reconstruction (R) using two different solvents for the dissolution of curcumin: (i) an alkaline aqueous solution (A), and (ii) ethanol (E). The reconstruction used the calcinated (460 °C for 18 h) form of the parent Mg2.5Al-LDH powder. All the solids were characterized by X-ray diffraction (XRD), and FTIR spectroscopy. The FTIR-ATR spectra of the all the powders except the powder prepared via reconstruction in ethanol exhibit LDH characteristics, consistent with the XRD results.Matrix Assisted Pulsed Laser Evaporation (MAPLE) was employed for the deposition of hybrid LDH-CR thin films. Aqueous solutions of the as prepared hybrid LDH-CR powders were frozen and used as targets for MAPLE depositions. The films were deposited using a nanosecond laser emitting at 266 nm. MAPLE is considered a “soft” deposition technique suitable to conserve the CR stability. XRD, scanning electron microscopy, FT-IR spectroscopy and fluorescence measurements were used to characterize the deposited films in order to evidence the influence of the preparation methods on the structural and photophysical characteristics of the hybrid LDH-CR films.

Synthesis of a novel dexamethasone intercalated layered double hydroxide nanohybrids and their deposition on anodized titanium nanotubes for drug delivery purposes

Dexamethasone, an anti-inflammatory drug, was intercalated in both Zn/Al-NO3 and Zn/Al-CO3 layered double hydroxides with three different LDH/DEXA molar ratios through ion-exchange technique. Then the maximum added drug nanohybrid (NL-1D) deposited into nanotubes of anodized titanium (ATS-NL-1D). The X-ray diffraction (XRD) demonstrated that dexamethasone anions are accommodated within the interlayer space of Zn/Al-NO3 LDHs, with the dspacing of 8.9 Å which became 21.215 Å after intercalation (NL-1D). However, it confirmed that dexamethasone anions only settled on the surface of Zn/Al-CO3 LDHs and we only demonstrated Zn/Al-CO3 data to prove that drug anions never intercalated into the interlayer space of these LDHs. The Fourier transform infrared spectroscopy (FTIR) also supported the formation of Zn/Al-NO3 LDHs and confirmed unsuccessful intercalation of the drug in Zn/Al-CO3 LDHs, therefore we continued our work with Zn/Al-NO3 LDHs. Thermal analysis (STA) showed that nanohybrids are more thermally stable than the drug alone. Furthermore, it demonstrated that dexamethasone loading for NL-1D was around 12%. In-vitro release study of LDH-DEXA nanohybrids suggested a considerable reduction in release rate due to the incarceration of drug molecules inside nanohybrids. Release rate showed even more reduction from ATS-NL-1D, because of entanglement of nanohybrid particles inside nanotubes of anodized titanium which justified the anodization process for implant application. Cell adhesion and viability studies revealed that ATS-NL-1D not only wasn’t toxic but also the osteoblast cells viability was more than 80% on these sheets. All in all, this work demonstrated that ATS-NL-1D is a suitable candidate for bone implant applications.

Effect of natural curcuminoids-intercalated layered double hydroxide nanohybrid against Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis: Abactericidal, antibiofilm, and mechanistic study.

The study aimed to determine the antibacterial/antibiofilm effect and mechanism of interaction of curcuminoids‐intercalated Mg/Al layered double hydroxide (curcuminoids‐LDH) against three different bacteria. Antimicrobial effect of curcuminoids‐LDH nanohybrid was investigated against P. aeruginosa, S. aureus, and E. faecalis (for both standard strains and clinical isolates), using agar well diffusion method. Minimum inhibitory concentrations (MIC) of planktonic bacteria were determined using the broth microdilution method. MIC of biofilms (MBIC 50) and killing time for 48 hr matured biofilms were determined by MTT (3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay. Scanning electron microscopy (SEM) was used to determine pre‐ and postexposure architecture of biofilms. The mechanism of the antibiofilm activity of curcuminoids‐LDH was determined using UV‐visible spectroscopy. All tested bacteria had given a zone of inhibition in the presence of curcuminoids‐LDH. The MIC values were 0.200 g/ml for P. aeruginosa, 0.025 g/ml for S. aureus, and 0.100 g/ml for E. faecalis. The 48 hr matured biofilms were reduced by curcuminoids‐LDH with an MBIC 50 of 0.100 g/ml. The minimum time to achieve MBIC 50 was 3 hr, and the reduction was constant until 48 hr. SEM images showed a significant reduction of biofilm cell density and exopolymer matrics for all biofilms in the presence of curcuminoids‐LDH. UV‐visible studies revealed the antibiofilm activity of curcuminoids‐LDH as due to the auto‐oxidation of curcuminoids. The oxidation products are more limited in both product concentration per unit time and the variety of products, compared to pure curcuminoids, resulting in sharper UV‐visible peaks than in the case of the latter. Curcuminoids‐LDH has a potential antibacterial activity against P. aeruginosa, S. aureus, and E. faecalis. An antibiofilm activity has been achieved within 3 hr of the treatment. Curcuminoids released from the LDH showed the antibacterial activity due to oxidation products interfering with bacterial cell functions, and also encapsulation in the LDH causes curcuminoids to exhibit the activity in a persistent manner compared to pure curcuminoids.