Magnetic Porous Controlled Fe3O4-Chitosan Nanostructure: An Ecofriendly Adsorbent for Efficient Removal of Azo Dyes

Carbon and metal based magnetic porous materials - Role in drug removal: A Comprehensive review

Development of effective adsorbents for the removal of contaminants from wastewater is indispensable due to increasing water scarcity and a lack of pure drinking water, which are prevailing as a result of rapid industrialization and population growth. Recently, the development of new adsorbents and their effective use without generating secondary waste is receiving huge consideration. In order to protect the environment from primary and secondary pollution, the development of adsorbents from wastes and their recycling have become conventional practices aimed at waste management. As a result, significant progress has been made in the synthesis of new porous carbon and metal-organic frameworks as adsorbents, with the objective of using them for the removal of pollutants. While many different kinds of pollutants are produced in the environment, drug pollutants are the most vicious because of their tendency to undergo significant structural changes, producing metabolites and residues with entirely different properties compared to their parent compounds. Chemical reactions involving oxidation, hydrolysis, and photolysis transform drugs. The resulting compounds can have detrimental effects on living beings that are present in soil and water. This review stresses the development of adsorbents with adjustable porosities for the broad removal of primary drug pollutants and their metabolites, which are formed as a result of drug transformations in environmental matrices. This keeps adsorbents from building up in the environment and prevents them from becoming significant pollutants in the future. Additionally, it stops secondary pollution caused by the deterioration of the used adsorbents. Focus on the development of effective adsorbents with flexible porosities allows for the complete removal of coexisting contaminants and makes a substantial contribution to wastewater management. In order to concentrate more on the development of flexible pore adsorbents, it is crucial to comprehend the milestones reached in the research and applications of porous magnetic adsorbents based on metal and carbon, which are discussed here.

Sorption behavior of chitosan nanoparticles for single and binary removal of cationic and anionic dyes from aqueous solution

In this study, chitosan nanoparticles (ChNs) were used as an adsorbent for single and simultaneous uptake of cationic (methylene blue (MB)) and anionic (methyl orange (MO)) dyes. ChNs were prepared based on the ionic gelation method using sodium tripolyphosphate (TPP) and characterized by zetasizer, FTIR, BET, SEM, XRD, and pHPZC. The studied parameters that affect removal efficiency included pH, time, and dyes' concentration. The results showed that in single-adsorption mode, the removal of MB is better in alkaline pH, contrary to MO uptake which presents higher removal efficiency in acidic media. The simultaneous removal of MB and MO from the mixture solution by ChNs could be achieved under neutral conditions. The adsorption kinetic results showed that adsorption of MB and MO for both single-adsorption and binary adsorption systems comply with the pseudo-second-order model. Langmuir, Freundlich, and Redlich-Peterson isotherms were used for the mathematical description of single-adsorption equilibrium, while non-modified Langmuir and extended Freundlich isotherms were used to fit the co-adsorption equilibrium results. The maximum adsorption capacities of MB and MO in a single dye adsorption system were 315.01 and 257.05 mg/g for MB and MO, respectively. On the other hand, and for binary adsorption system, the adsorption capacities were 49.05 and 137.03 mg/g, respectively. The adsorption capacity of MB decreases in solution containing MO and vice versa, suggesting an antagonistic behavior of MB and MO on ChNs. Overall, ChNs could be a candidate for single and binary removal of MB and MO in dye-containing wastewater.

Hydrogels Based on Chitosan and Nanoparticles and Their Suitability for Dyes Adsorption from Aqueous Media: Assessment of the Last-Decade Progresses

Water is one of the fundamental resources for the existence of humans and the environment. Throughout time, due to urbanization, expanding population, increased agricultural production, and intense industrialization, significant pollution with persistent contaminants has been noted, placing the water quality in danger. As a consequence, different procedures and various technologies have been tested and used in order to ensure that water sources are safe for use. The adsorption process is often considered for wastewater treatment due to its straightforward design, low investment cost, availability, avoidance of additional chemicals, lack of undesirable byproducts, and demonstrated significant efficacious potential for treating and eliminating organic contaminants. To accomplish its application, the need to develop innovative materials has become an essential goal. In this context, an overview of recent advances in hydrogels based on chitosan and nanocomposites and their application for the depollution of wastewater contaminated with dyes is reported herein. The present review focuses on (i) the challenges raised by the synthesis process and characterization of the different hydrogels; (ii) the discussion of the impact of the main parameters affecting the adsorption process; (iii) the understanding of the adsorption isotherms, kinetics, and thermodynamic behavior; and (iv) the examination of the possibility of recycling and reusing the hydrogels.

Magnetic Chitosan for the Removal of Sulfamethoxazole from Tertiary Wastewaters

Magnetic chitosan nanoparticles, synthesized by in situ precipitation, have been used as adsorbents to remove sulfamethoxazole (SMX), a sulfonamide antibiotic dangerous due to its capacity to enter ecosystems. The adsorption of SMX has been carried out in the presence of tertiary wastewaters from a depuration plant to obtain more realistic results. The effect of pH on the adsorption capacity significantly changed when carrying out the experiments in the presence of wastewater. This change has been explained while taking into account the charge properties of both the antibiotic and the magnetic chitosan. The composition of wastewaters has been characterized and discussed as regards its effect on the adsorption capacity of the magnetic chitosan. The models of Elovich and Freundlich have been selected to describe the adsorption kinetics and the adsorption isotherms, respectively. The analysis of these models has suggested that the adsorption mechanism is based on strong chemical interactions between the SMX and the magnetic chitosan, leading to the formation of an SMX multilayer.

Fe3O4-chitosan nanocomposite as a magnetic biosorbent for removal of nickel and cobalt heavy metals from polluted water

Recently, natural polymers like chitosan have gained attention as promising adsorbents for water treatment. By combining chitosan with magnetic nanoparticles, their adsorption capabilities can be enhanced. In this study, chitosan-magnetite nanocomposite (CMNC) was synthesized via coprecipitation method to remove nickel and cobalt from aqueous solutions. The physicochemical properties of the synthesized CMNC were investigated by various techniques, including FESEM, TEM, XPS, FTIR, XRD, and VSM. The electron microscopy results confirmed the uniform dispersion of magnetite nanoparticles within CMNC nanocomposites, while VSM confirmed their significant magnetic properties. The adsorption experiments showed that at optimal conditions (pH = 6, contact time = 2 h, adsorbent dosage = 2 g/l), CMNC has high adsorption capacities of 30.03 mg/g for Ni2+ and 53.19 mg/g for Co2+. Furthermore, the adsorption data fitted best with the Langmuir isotherm, show that the active sites on CMNC are energetically homogenous. According to kinetic analysis, the experimental data were in good agreement with both pseudo-second-order and intra-particle diffusion models, which suggest that chemical sorption, along with mass transfer steps, influence the overall adsorption process. Finally, investigating the thermodynamic parameters (∆Gads, ∆Hads, ∆Sads) showed that the adsorption process on CMNC was endothermic and spontaneous, with stronger interactions observed between CMNC and Co2+ compared to Ni2+.

Use of Chitosan-Based Polyelectrolyte Complexes for Its Potential Application in Active Food Packaging: A Review of Recent Literature

The current challenges in the food packaging field are, on one side, replacing plastic from non-renewable sources with biopolymers and, on the other hand, generating a packaging material with attractive properties for the consumer. Currently, the consumer is ecologically concerned; the food packaging industry must think ahead to satisfy their needs. In this context, the utilization of polyelectrolyte complexes (PECs) in this industry presents itself as an excellent candidate for fulfilling these requirements. PECs possess enticing characteristics such as encapsulation, protection, and transportation, among others. On the other hand, diverse types of biopolymers have been used in the formation of PECs, such as alginate, cellulose, gelatin, collagen, and so on. Hence, this paper reviews the use of PECs in food packaging where chitosan forms polyelectrolyte complexes.

Preparation 2-hydroxy-1-naphthaldehyde cross-linked Fe3O4@chitosan-polyacrylamide nanocomposite for removal of everzol black from aqueous solutions

In this study, new 2-hydroxy-1-naphthaldehyde linked Fe₃O₄/chitosan-polyacrylamide nanocomposite (Fe₃O₄@CS@Am@Nph) were prepared. The synthesized nanocomposite was characterized by (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), vibrating Sample Magnetometry (VSM) and Termogravimetric Analysis (TGA). The 2-hydroxy-1-naphthaldehyde modified Fe₃O₄@CS@Am@Nph nanocomposite was used as an effective adsorbent for removal of everzol black from aqueous solutions by batch adsorption procedure. The effects of important parameters on the surface absorption process of everzol black dye, including pH, contact time, adsorbent dosage and initial dye concentration were studied. The Langmuir, Freundlich and Temkin adsorption models were used to describe adsorption isotherms and constants. The equilibrium results revealed that the adsorption behavior of the everzol black dye on the Fe₃O₄@CS@Am@Nph nanocomposite fitted well with the Langmuir model. On the basis of the Langmuir analysis, the maximum adsorption capacity (qm) of the Fe₃O₄@CS@Am@Nph for everzol black was found to be 63.69 mg/g. The kinetic studies indicated that adsorption in all cases to be a pseudo second-order process. Further, the thermodynamic studies showed the adsorption to be a spontaneous and endothermic process.

Fe3O4 modified chitosan based co-polymeric magnetic composite hydrogel: Synthesis, characterization and evaluation for the removal of methylene blue from aqueous solutions

The present research comprises the fabrication of magnetic Fe₃O₄ incorporated chitosan grafted acrylamide and N-vinylimidazole composite hydrogels (CANFe-1 to CANFe-7) via water mediated free radical polymerization technique using ammonium persulfate/tetramethyl ethylenediamine as initiator. The prepared magnetic composite hydrogel was characterized by FT-IR, TGA, SEM, XRD, and VSM analysis. A swelling study was performed to understand the swelling behavior and found CANFe-4 to be more efficient with maximum swelling hence entire removal studies were performed with CANFe-4. pH_PZC analysis was performed to determine pH sensitive adsorptive removal of cationic dye (methylene blue). pH dependent adsorption of methylene blue was dominant at pH = 8 with a maximum adsorption capacity of 860 mg/g. After the adsorptive removal of methylene blue from aqueous media, a composite hydrogel can conveniently be separated from the solution with the use of an external magnet. Adsorption of methylene blue is well explained with the Langmuir adsorption isotherm and Pseudo-Second-Order kinetic model that validates chemisorption. Moreover, it was found that CANFe-4 could be frequently applied for the adsorptive removal of methylene blue for 5 consecutive adsorption-desorption cycles with 92.4 % removal efficiency. Hence, CANFe-4 offers a promising recyclable, sustainable, robust, and efficient adsorbent for wastewater treatment.

Development of Nanocomposite Coatings

This Special Issue in Nanomaterials, "Development of Nanocomposite Coatings", was set up with the aim to provide authors with an opportunity to showcase their latest developments in this field [...].

Highly Efficient Adsorption of Tetracycline Using Chitosan-Based Magnetic Adsorbent

Herein, tetracycline adsorption employing magnetic chitosan (CS·Fe₃O₄) as the adsorbent is reported. The magnetic adsorbent was synthesized by the co-precipitation method and characterized through FTIR, XRD, SEM, and VSM analyses. The experimental data showed that the highest maximum adsorption capacity was reached at pH 7.0 (211.21 mg g^-1). The efficiency of the magnetic adsorbent in tetracycline removal was dependent on the pH, initial concentration of adsorbate, and the adsorbent dosage. Additionally, the ionic strength showed a significant effect on the process. The equilibrium and kinetics studies demonstrate that Sips and Elovich models showed the best adjustment for experimental data, suggesting that the adsorption occurs in a heterogeneous surface and predominantly by chemical mechanisms. The experimental results suggest that tetracycline adsorption is mainly governed by the hydrogen bonds and cation-π interactions due to its pH dependence as well as the enhancement in the removal efficiency with the magnetite incorporation on the chitosan surface, respectively. Thermodynamic parameters indicate a spontaneous and exothermic process. Finally, magnetic chitosan proves to be efficient in TC removal even after several adsorption/desorption cycles.

Influence of magnetite incorporation into chitosan on the adsorption of the methotrexate and in vitro cytotoxicity

Emerging pollutants are a group of substances involved in environmental contamination resulting mostly from incomplete drug metabolism, associated with inadequate disposal and ineffective effluent treatment techniques. Methotrexate (MTX), for instance, is excreted at high concentrations in unchanged form through the urine. Although the MTX is still effective in cancer and autoimmune disease treatment, this drug shows the ability of bioaccumulation and toxicity to the organism. Thus, the present work aimed to evaluate the adsorption of the MTX drug onto magnetic nanocomposites containing different amounts of incorporated magnetite (1:1, 1:5, and 1:10 wt%), combining the theoretical-experimental study as well as the in vitro cytotoxicity. Moreover, equilibrium studies (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Hill, Redlich-Peterson, and Sips), kinetic (PFO, PSO, and IPD), and thermodynamic (ΔG°, ΔH°, and ΔS°) were used to describe the experimental data, and ab initio simulations were employed in the theoretical study. Magnetic nanocomposites were synthesized by the co-precipitation method using only FeCl₂ as the iron precursor. Adsorbents were characterized by FTIR, XRD, Raman, SEM-EDS, BET, and VSM analysis. Meanwhile, cytotoxic effects on L929 and A375 cell lines were evaluated through MTT, NR, and LDH assays. The adsorption of the MTX was carried out in a typical batch system, exploring the different experimental conditions. The theoretical study suggests the occurrence of chemisorption between CS·Fe₃O₄-MTX. The maximum adsorption capacity of MTX was 285.92 mg g^-1, using 0.125 g L^-1 of CS·Fe₃O₄ 1:1, with an initial concentration of the MTX (50 mg L^-1), pH 4.0 at 293 ± 1.00 K. The best adjustment of equilibrium and kinetic data were the Sips (low values for statistical errors) and PSO (q_e = 96.73 mg g^-1) models, respectively. Thermodynamic study shows that the adsorption occurred spontaneously (ΔG° < 0), with exothermic (ΔH° =  - 4698.89 kJ mol^-1) and random at the solid-solution interface (ΔS° = 1,476,022.00 kJ mol^-1 k^-1) behavior. Finally, the in vitro study shows that magnetic nanomaterials exhibit higher cytotoxicity in melanoma cells. Therefore, the magnetic nanocomposite reveals to be not only an excellent tool for water remediation studies but also a promising platform for drug delivery.

Aspergillus tamarii mediated green synthesis of magnetic chitosan beads for sustainable remediation of wastewater contaminants

The release of different hazardous substances into the water bodies during the industrial and textile processing stages is a serious problem in recent decades. This study focuses on the potentiality of Fe₃O₄-NPs-based polymer in sustainable bioremediation of toxic substances from contaminated water. The biosynthesis of Fe₃O₄-NPs by A. tamarii was performed for the first time. The effect of different independent variables on the Fe₃O₄-NPs production were optimized using Plackett-Burman design and central composite design (CCD) of Response Surface Methodology. The optimum Fe₃O₄-NPs production was determined using incubation period (24 h), temperature (30 °C), pH (12), stirring speed (100 rpm) and stirring time (1 h). The incorporation of Fe₃O₄-NPs into chitosan beads was successfully performed using sol-gel method. The modified nanocomposite exhibited remarkable removal capability with improved stability and regeneration, compared to control beads. The optimal decolorization was 94.7% at 1.5 g/l after 90 min of treatment process. The reusability of biosorbent beads displayed 75.35% decolorization after the 7th cycle. The results showed a highly significant reduction of physico-chemical parameters (pH, TDS, TSS, COD, EC, and PO₄) of contaminated wastewater. The sorption trials marked Fe₃O₄-NPs-based biopolymer as efficient and sustainable biosorbent for the elimination of hazardous toxic pollutants of wastewater in a high-speed rate.

Potential applications of spent adsorbents and catalysts: Re-valorization of waste

Water pollution has increased with the growth of human population and its industrial activities. Textile effluents constitute a particular threat due to the presence of heavy metals and dyes. Adsorption is one of the most applied technologies in contaminant removal owing to its high efficiency, low cost, practical implementation and possibility to operate in several experimental conditions. However, this process implies the generation of spent materials, representing a limitation to scale-up. Although the applications of exhausted solids in effluent treatments have not been extensively reviewed before, their reutilization appears to be an environmentally and economically attainable alternative. This work summarizes the potential value of solids post-use. The open literature reports that spent adsorbents based on polysaccharides with iron oxides may adsorb up to 1 g g^-1 of organic pollutants and up to near 100% of metallic ions from wastewater (Cu²⁺, Cd²⁺, Zn²⁺, Pb²⁺). The studied conditions vary from 30 to 60 °C, 0,05 to 6 g L^-1 of adsorbent, 10 mg L^-1 to 250 mg L^-1 of organic pollutants (dyes) and pH between 2 and 8. Spent adsorbents in dye removal have proven to have near 95% efficiency in metallic ion adsorption. Otherwise, the spent solids could be applied to remove Ca²⁺ and Mg²⁺ to decrease the hardness of water. Furthermore, at the end-of-life, these materials could be used in cement and ceramic production. To achieve these aims, it is necessary to design the bioadsorbents and biocatalysts considering not only their primary uses (as adsorbent of organic pollutants), but also secondary applications (as toxic metal or hardness removal) and even their final destination (as additive in ceramic or cement production). Finally, further studies are required on the composition, properties, stability at long-term and the life-cycle cost of these materials when they are applied in the construction industry.

Photocatalytic Efficacy of Heterocyclic Base Grafted Chitosan Magnetite Nanoparticles on Sorption of Pb(II); Application on Mining Effluent

Development of bio-based sorbents (i.e., chitosan moieties) at nanoscale size for the removal of metal contaminants is the main target of this research. Grafting with thiazole heterocyclic derivative gives fast kinetics sorption, highly metal loading, and good recyclability for mining leaching solution. Different analyses tools including (thermogravimetric analysis (TGA), scanning electron microscope and energy dispersive spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR), BET surface area (nitrogen sorption desorption), titration, and TEM (transmission electron microscopy)) were used to investigate the chemical and textural properties of the functionalized sorbent. The sorption was measured in normal visible light and under UV emission. The highest capacity was measured at pH 5, which reached 0.251 mmol Pb g−1 in visible light compared with 0.346 mmol Pb g−1 under UV for the pristine crosslinked chitosan (MCc). The sorption performances were improved by functionalization; (0.7814 and 1.014 mmol Pb g−1) for the functionalized sorbent (MCa-ATA) under visible light and UV, respectively. PFORE (pseudo-first-order rate equation) and RIDE (resistance to intraparticle diffusion) fit kinetics, the Sips equation is the most fit profile for the sorption isotherms for the MCc in either light and UV processes, while PFORE and RIDE for kinetics under light and UV for MCa-ATA and Sips in light and Sips and Langmuir under the UV emission. Finally, the sorbent was investigated toward a raffinate solution from ore processing and shows promising extraction tools for the most interesting elements.

Chitosan@Carboxymethylcellulose/CuO-Co2O3 Nanoadsorbent as a Super Catalyst for the Removal of Water Pollutants

In this work, an efficient nanocatalyst was developed based on nanoadsorbent beads. Herein, carboxymethyl cellulose–copper oxide-cobalt oxide nanocomposite beads (CMC/CuO-Co2O3) crosslinked by using AlCl3 were successfully prepared. The beads were then coated with chitosan (Cs), Cs@CMC/CuO-Co2O3. The prepared beads, CMC/CuO-Co2O3 and Cs@CMC/CuO-Co2O3, were utilized as adsorbents for heavy metal ions (Ni, Fe, Ag and Zn). By using CMC/CuO-Co2O3 and Cs@CMC/CuO-Co2O3, the distribution coefficients (Kd) for Ni, Fe, Ag and Zn were (41.166 and 6173.6 mLg−1), (136.3 and 1500 mLg−1), (20,739.1 and 1941.1 mLg−1) and (86.9 and 2333.3 mLg−1), respectively. Thus, Ni was highly adsorbed by Cs@CMC/CuO-Co2O3 beads. The metal ion adsorbed on the beads were converted into nanoparticles by treating with reducing agent (NaBH4) and named Ni/Cs@CMC/CuO-Co2O3. Further, the prepared nanoparticles-decorated beads (Ni/Cs@CMC/CuO-Co2O3) were utilized as nanocatalysts for the reduction of organic and inorganic pollutants (4-nitophenol, MO, EY dyes and potassium ferricyanide K3[Fe(CN)6]) in the presence of NaBH4. Among all catalysts, Ni/Cs@CMC/CuO-Co2O3 had the highest catalytic activity toward MO, EY and K3[Fe(CN)6], removing up to 98% in 2.0 min, 90 % in 6.0 min and 91% in 6.0 min, respectively. The reduction rate constants of MO, EY, 4-NP and K3[Fe(CN)6] were 1.06 × 10−1, 4.58 × 10−3, 4.26 × 10−3 and 5.1 × 10−3 s−1, respectively. Additionally, the catalytic activity of the Ni/Cs@CMC/CuO-Co2O3 beads was effectively optimized. The stability and recyclability of the beads were tested up to five times for the catalytic reduction of MO, EY and K3[Fe(CN)6]. It was confirmed that the designed nanocomposite beads are ecofriendly and efficient with high strength and stability as catalysts for the reduction of organic and inorganic pollutants.

Engineered Magnetic Carbon-Based Adsorbents for the Removal of Water Priority Pollutants: An Overview

This review covers the preparation, characterization, and application of magnetic adsorbents obtained from carbon-based sources and their application in the adsorption of both inorganic and organic pollutants from water. Different preparation routes to obtain magnetic adsorbents from activated carbon, biochar, hydrochar, graphene, carbon dots, carbon nanotubes, and carbon nanocages, including the magnetic phase incorporated on the solid surface, are described and discussed. The performance of these adsorbents is analyzed for the removal of fluoride, arsenic, heavy metals, dyes, pesticides, pharmaceuticals, and other emerging and relevant water pollutants. Properties of these adsorbents and the corresponding adsorption mechanisms have been included in this review. Overall, this type of magnetic adsorbents offers an alternative for facing the operational problems associated to adsorption process in water treatment. However, some gaps have been identified in the proper physicochemical characterization of these adsorbents, the development of green and low-cost preparation methods for their industrial production and commercialization, the regeneration and final disposal of spent adsorbents, and their application in the multicomponent adsorption of water pollutants.

Appraisal of Chitosan-Gum Arabic-Coated Bipolymeric Nanocarriers for Efficient Dye Removal and Eradication of the Plant Pathogen Botrytis cinerea

The treatment of textile wastewater comprising many dyes as contaminants endures an essential task for environmental remediation. In addition, combating antifungal multidrug resistance (MDR) is an intimidating task, specifically owing to the limited options of alternative drugs with multitarget drug mechanisms. Incorporating natural polymeric biomaterials for drug delivery provides desirable properties for drug molecules, effectively eradicating MDR fungal growth. The current study fabricated the bipolymeric drug delivery system using chitosan-gum arabic-coated liposome 5ID nanoparticles (CS-GA-5ID-LP-NPs). This study focused on improving the solubility and sustained release profile of 5I-1H-indole (5ID). These NPs were characterized and tested mechanically as a dye adsorbent as well as their antifungal potencies against the plant pathogen, Botrytis cinerea. CS-GA-5ID-LP-NPs showed 71.23% congo red dye removal compared to crystal violet and phenol red from water and effectively had an antifungal effect on B. cinerea at 25 μg/mL MIC concentrations. The mechanism of the inhibition of B. cinerea via CS-GA-5ID-LP-NPs was attributed to stabilized microtubule polymerization in silico and in vitro. This study opens a new avenue for designing polymeric NPs as adsorbents and antifungal agents for environmental and agriculture remediation.

Hydroxyapatite-Based Magnetic Bionanocomposite as Pharmaceuticals Carriers in Chitosan Scaffolds

Hydroxyapatite (HA) is a bioceramic very similar to the mineral component of bones and teeth. It is well established that osteoblasts grow better onto HA-coated metals than on metals alone. Herein, the preparation of a new system consisting of magnetite (Fe3O4) and HA functionalized with oleic acid and simvastatin (SIMV), and incorporated in chitosan (CHI) scaffolds, was undertaken. HA was synthesized by the hydrothermal method, while Fe3O4 was synthesized by co-precipitation. The polymer matrix was obtained using a 2% CHI solution, and allowed to stir for 2 h. The final material was freeze-dried to produce scaffolds. The magnetic properties remained unchanged after the formation of the composite, as well as after the preparation of the scaffolds, maintaining the superparamagnetism. CHI scaffolds were analyzed by scanning electronic spectroscopy (SEM) and showed a high porosity, with very evident cavities, which provides the functionality of bone growth support during the remineralization process in possible regions affected by bone tissue losses. The synthesized composite showed an average particle size between 15 and 23 nm for particles (HA and Fe3O4). The scaffolds showed considerable porosity, which is important for the performance of various functions of the tissue structure. Moreover, the addition of simvastatin in the system can promote bone formation.

Preparation and Properties of Corn Starch/Chitin Composite Films Cross-Linked by Maleic Anhydride

To improve the functional properties of starch-based films, chitin (CH) was prepared from shrimp shell powder and incorporated into corn starch (CS) matrix. Before blending, maleic anhydride (MA) was introduced as a cross-linker. Composite CS/MA-CH films were obtained by casting-evaporation approach. Mechanical property estimation showed that addition of 0–7 wt % MA-CH improved the tensile strength of starch films from 3.89 MPa to 9.32 MPa. Elongation at break of the films decreased with the addition of MA-CH, but the decrease was obviously reduced than previous studies. Morphology analysis revealed that MA-CH homogeneously dispersed in starch matrix and no cracks were found in the CS/MA-CH films. Incorporation of MA-CH decreased the water vapor permeability of starch films. The water uptake of the films was reduced when the dosage of MA-CH was below 5 wt %. Water contact angles of the starch films increased from 22° to 86° with 9 wt % MA-CH incorporation. Besides, the composite films showed better inhibition effect against Escherichia coli and Staphylococcus aureus than pure starch films.