Immobilization of enzymes enhances their properties for efficient utilization in industrial processes. Magnetic nanoparticles, due to their high surface area, large surface-to-volume ratio and easy separation under external magnetic fields, are highly valued. Significant progress has been made to develop new catalytic systems that are immobilized onto magnetic nanocarriers. This review provides an overview of recent developments in enzyme immobilization and stabilization protocols using this technology. The current applications of immobilized enzymes based on magnetic nanoparticles are summarized and future growth prospects are discussed. Recommendations are also given for areas of future research.

Selenium as an essential trace element for the health of the humans was used to hydrothermally synthesis of selenium nanoparticle (Se NPs) using Aloe vera leaf extract (ALE). Effects of synthesis parameters namely; amount of ALE (1–5 ml) and amount of Na2SeO3 solution (10–30 ml), on the particle size and colour intensity of the solution containing Se NPs were studied using response surface methodology. FT-IR spectroscopy, UV-Vis spectrophotometry, DLS analyzer and TEM were used to determine the specifications of the ALE and synthesized Se NPs. Obtained results indicated that the ALE contained several bioactive compounds, which they had hydroxyl and amide І groups in their structures and these two functional groups had key roles in the reduction of the selenium ions to form Se NPs and stabilizing of them. Furthermore, spherical fabricated Se NPs using obtained optimum synthesis parameters, 4.92 mL of ALE and 13.03 mL of Na2SeO3 solution, had colour intensity, mean particle size, zeta potential and polydispersity index values of 3.0% a.u., 50 nm, -18 mV and 0.344, respectively according to the DLS analysis. The synthesized Se NPs had also high antibacterial and antifungal activities against 4 selected pathogenic bacteria and spoilage fungi strains.

The present study focuses on the biogenic synthesis of selenium nanoparticles (Se NPs) using Pelargonium zonale leaf extract under microwave irradiation. Response surface methodology was used to evaluate the effects of the synthesis parameters, namely amounts of the leaf extract (0.5–2.5 ml) and amounts of the 10 mm sodium selenite solutions (15–65 ml), at constant microwave heating (4 min), on the concentration and particle size of the fabricated Se NPs, optimize the synthesis conditions and verify the generated models and the procedures. The obtained results indicated that Se NPs with preferable attributes of mean particle size (50 nm), zeta potential (−24.6 mV), absorbance [34.6% absorbance units (a.u.)] and broad absorption peak (319 nm) were formed at the optimum synthesis conditions including amounts of 1.48 ml and 15 ml Pelargonium leaf extract and sodium selenite solution, respectively. The antibacterial activities of the synthesized Se NPs against Escherichia coli and Staphylococcus aureus indicated that the created NPs had higher antibacterial activities toward the Gram-positive bacteria. Furthermore, the synthesized Se NPs indicated higher antifungal activities against Colletotrichum coccodes and Penicillium digitatum.

The potential of magnetic nanoparticles (MNPs) in drug delivery systems (DDSs) is mainly related to its magnetic core and surface coating. These coatings can eliminate or minimize their aggregation under physiological conditions. Also, they can provide functional groups for bioconjugation to anticancer drugs and/or targeted ligands. Chitosan, as a derivative of chitin, is an attractive natural biopolymer from renewable resources with the presence of reactive amino and hydroxyl functional groups in its structure. Chitosan nanoparticles (NPs), due to their huge surface to volume ratio as compared to the chitosan in its bulk form, have outstanding physico-chemical, antimicrobial and biological properties. These unique properties make chitosan NPs a promising biopolymer for the application of DDSs. In this review, the current state and challenges for the application magnetic chitosan NPs in drug delivery systems were investigated. The present review also revisits the limitations and commercial impediments to provide insight for future works.

In recent decades, magnetic iron nanoparticles (NPs) have attracted much attention due to properties such as superparamagnetism, high surface area, large surface-to-volume ratio, and easy separation under external magnetic fields. Therefore, magnetic iron oxides have potential for use in numerous applications, including magnetic resonance imaging contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, drug delivery, hyperthermia, and cell separation. This review provides an updated and integrated focus on the fabrication and characterization of suitable magnetic iron NPs for biotechnological applications. The possible perspective and some challenges in the further development of these NPs are also discussed.

Cancer is one of the major malignant diseases in the world. Current anti tumor agents are restricted during the chemotherapy due to their poor solubility in aqueous media, multidrug resistance problems, cytotoxicity, and serious side effects to healthy tissues. Development of targeted drug nanocarriers would enhance the undesirable effects of anticancer drugs and also selectively deliver them to cancerous tissues. Variety of nanocarriers such as micelles, polymeric nanoparticles, liposomes nanogels, dendrimers, and carbon nanotubes have been used for targeted delivery of anticancer agents. These nanocarriers transfer loaded drugs to desired sites through passive or active efficacy mechanisms. Chitosan and its derivatives, due to their unique properties such as hydrophilicity, biocompatibility, and biodegradability, have attracted attention to be used in nanocarriers. Grafting cancer-specific ligands onto the Chitosan nanoparticles, which leads to ligand-receptor interactions, has been successfully developed as active targeting. Chitosan-conjugated components also respond to external or internal physical and chemical stimulus in targeted tumors that is called environment triggers. In this study, mechanisms of targeted tumor deliveries via nanocarriers were explained; specifically, chitosan-based nanocarriers in tumor-targeting drug delivery were also discussed.

Fuel cells are electrochemical devices which convert chemical energy into electrical energy. Fuel cells have attracted attention due to their potential as a promising alternative to traditional power sources. More recently, efficient and environmentally benign biopolymer "chitosan" have been extensively investigated as a novel material for its application in fuel cells. This biopolymer can be used in both membrane electrolyte and electrode in various fuel cells such as alkaline polymer electrolyte fuel cells, direct methanol fuel cells and biofuel cells. This review provides an overview of main available fuel cells following by application of chitosan as novel biopolymer in fuel cells technology. Recent achievements are included and recommendations are also given for areas of future research.

Silver nanoparticles (AgNPs) were synthesized using Aloe vera leaf extract as both reducing and stabilizing agents via microwave irradiation method. The effects of the microwave exposure time and the amount of AgNO3 solution on the mean particle size and concentration of the synthesized AgNPs solution were investigated using response surface methodology. The synthesized AgNPs were characterized by transmission electron microscopy, UV-Vis spectroscopy, and dynamic light scattering. Well-dispersed and spherically fabricated AgNPs with mean particle size (46 nm) and maximum concentration (64 ppm) and zeta potential (+15.5 mV), were obtained at optimal synthesis conditions, using 9 ml of AgNO3 (1 mm) and 0.1 ml of Aloe vera extract during microwave exposure time of 360 s. The antibacterial activity of the synthesized AgNPs was tested using Escherichia coli and Staphylococcus aureus bacteria and the obtained results indicated their significant inhibitory effects against these two Gram-negative and Gram-positive bacteria.