Phosphorus (P) is a macronutrient of high consumption required by plants. Most agricultural soils around the world are poor in phosphorus and P fertilizers are used as a remedy. Not only are the fertilizers low in use efficiency but their application has also exacerbated the eutrophication of water bodies and the associated environmental pollution. This is while P fertilizers are extracted from the finite and non-renewable phosphate rock reserves, causing their rising prices over time as more P fertilizers will be needed to produce more food for the growing global population. P fertilizer management is, therefore, a key parameter in agricultural production. This is why a lot of attention has been recently paid to the application of sustained/controlled-release P fertilizers (SRF/CRF) in order to improve upon P use efficiency and plant growth at reduced environmental costs. The designation SRF/CRF is due to the lower water solubility of such fertilizers compared to conventional ones so that nutrients are supplied to plant roots over longer periods of time. Unlike SRFs, CRFs are characterized by well-controlled nutrient release rate, pattern, and duration. The methods used to manufacture P SRF include: 1) Coating the fertilizer with such materials as: a) polymers (including biodegradable polymers like chitosan, water-superabsorbent polymers, PVDC copolymers, polyolefins, polyurethanes, urea-formaldehyde resins, polyesters, and alkyd resins), b) sulfur, c) sulfur-polymers, d) organic acids, e) paraffin, f) clays, and g) fly ash; 2) Preparing SRFs from materials with a low solubility or a low mineralization rate; 3) Conversion of phosphate rock into P SRF using such different methods as partial acidification and phosphate solubilizing microorganisms; 4) Manufacturing P SRFs via nanotechnology-based techniques; 5) Producing P SRFs using phosphate-loaded layered double hydroxides, biochar, and hydrsochar; and 6) Using fly ash to manufacture SRF. The present article examines these methods and the effects of each on P use efficiency and the growth of different plants. It is generally concluded that P SRFs or CRFs improve P use efficiency and plant growth.

Adrug delivery process at a particular organ or site and at a specific time requires drug dose adjustment to reduce side effects and accelerate faster healing. The three parameters of time، site and release rate can be modulated by controlled drug delivery systems. Hydrogels are hydrophilic polymers and copolymers with three-dimensional network structures that nowadays are used in new controlled drug delivery systems. These macromolecules can respond to external stimuli such as temperature، pH and ionic strength. In this study، biocompatible acrylic hydrogels، synthesized by ultrasound، were studied to examine controlled drug release of Fluvoxamine. A pulsed power ultrasound was applied to the reaction mixture from the tip of a probe unit. It was found that hydrogel formation was faster using ultrasound. The results showed that ultrasonic irradiation significantly reduced the reaction time and increased efficiency. Additionally، increasing glycerol in the solution improved the viscosity of the reaction towards higher reaction rate. Also، we studied the stimuli sensitivity and swelling of hydrogels، and the rate of drug release at different temperatures and pH media. The results showed that the ultrasound irradiated acrylic hydrogels were sensitized towards pH and temperature variations. These hydrogels، due to their highly porous structure، were capable to load and release the drug rapidly and their performances were affected by pH and temperature. Also، the results showed that in a simulated body environment، the hydrogels were suitable options as controlled drug delivery systems in intestinal media. The ultrasonic polymerization method described here has a wide range of applications in biomaterial synthesis where initiators are not desired. The method adopted in this study can be developed for other gels and drugs.

Controlled release of drugs can reduce the undesired effects of drug level fluctuations, and diminish the side effects as well as improve the therapeutic outcome of the drugs. In recent year, the scope of the drug delivery systems has been greatly expanded by the development of various hydrogels. The present work has focused on the design of a pH sensitive drug delivery system (DDS) based on starch, acrylic acid (AA) and β-cyclodextrins for controlled delivery of indomethacin. The hydrogels were prepared via graft polymerization of acrylic acid (AA) onto starch and β-cyclodextrins backbones by a free radical polymerization technique. Cyclodextrins are able to form water-soluble complexes with many lipophilic water-insoluble drugs. In aqueous solutions, the drug molecules located in the central cavity of the cyclodextrin are in a dynamic equilibrium with free drug molecules. The interaction of drug with the polymer was evidenced by FTIR spectroscopy and thermal gravimetric analysis (TGA). The morphology of the samples was examined by scanning electron microscopy (SEM). The results showed that the hydrogels have good porosity and provided high surface area for the loading and release of drugs. Drug release behavior was carried out at physiological conditions of phosphate buffer, pH 8. In basic pH (like the intestine medium) the hydrogels released the indomethacin, but in acidic pH (like the stomach medium) there was no tendency to drug release. By increasing the amount of cyclodextrin, the rate of drug loading and release increased due to the dynamic equilibrium and interaction between the loaded drug and the cyclodextrin. This study has demonstrated that the hydrogel matrices are potentially suitable for controlled-release systems.

Cellulose nanofibers/SiO2 nanocomposite was prepared by extraction of cellulose nanofibers (CNFs) from Yucca leaves, followed by immobilization of SiO2 nanoparticles on the surface of cellulose nanofibers denoted as SiO2@CNFs. Prepared SiO2@CNFs nanocomposite was characterized using various techniques, including Fourier Transform Infra-Red (FT-IR), X-Ray Diffraction (XRD), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy Dispersive Spectroscopy (EDS) analysis, and used as controlled drug delivery system for the release of doxorubicin, an anticancer drug. CNFs exhibited higher loading level of doxorubicin (79.82%) than SiO2@CNFs (72.67%), while CNFs exhibited rapid drug release, but SiO2@CNFs showed controlled drug release properties. Doxorubicin release from CNFs is not pH sensitive, as CNFs released high content of doxorubicin, 94.0% and 88.0% within 5-7 h, at both pH values of 4.5 and 7.4, respectively. However, the release of doxorubicin from SiO2@CNFs occurred slowly, and could be controlled by pH, as cumulative release percentage of doxorubicin from SiO2@CNFs were measured to be 73.5% at pH = 4.5, while 17.07% at pH = 7.4 after 48 h. Doxorubicin release kinetic was studied by fitting the experimental data with well-known kinetic models, including zero order, first order, Higuchi, Korsmeyer-Peppas, Hixson-Corwell, Weibull and Gompertz models. Results revealed that the doxorubicin release from SiO2@CNFs is well fitted with Higuchi and Hixson–Crowell models at pH = 4.5 and Hixson–Crowell model at pH = 7.4. Fitting the date using Korsmeyer-Peppas indicated the nonFickian diffusion of doxorubicin from SiO2@CNFs at pH = 4.5 by n values of 0.4755, and Fickian type diffusion at pH = 7.4 by n values of 0.3359.

Curcumin is a yellow polyphenol extracted primarily from the plant Curcuma longa, but also from several other members of the ginger family.Many nanoscale systems have been extensively used for drug loading and release to get around curcumin's low bioavailability and aqueous solubility, highlight its functional properties, and broaden its applications in the pharmaceutical industry.Chitosan has been used as a natural biopolymer extensively for many years. Its polycationic properties, biocompatibility, biodegradability, non-toxicity, and lack of allergenicity all led to studies on it. The main focus in the discovery of curcumin involves its anti-cancer properties. It is well known that curcumin inhibits the signal transmission of cancer cell growth and thus angiogenesis and also causes tumor cell apoptosis. The modification of chitosan for various applications can be easily achieved due to the abundant active groups (NH2 and OH) in the main chainFor the release of curcumin, numerous chitosan-based nanocarriers with distinct properties have been developed, including nanocomposites, nanoemulsions, nanotubes, and nanofibers. The controlled release of the drug is to maintain the optimal therapeutic concentration of the drug in the blood, which increases the shelf life and duration of activity of drugs with a short half-life. Controlled drug release makes the drug release rate predictable and repeatable for prolonged release drugs. Therefore, the development of colloidal systems for curcumin release encapsulation is a promising strategy to overcome the limitations of drug release. The physical and chemical characteristics of chitosan-based nanocarriers, including surface charge, morphology, encapsulation driving force, and release characteristics, are examined in this study and the effectiveness of chitosan-based nanocarriers for pharmaceutical applications is determined by these characteristics.

During recent years, nanocomposites as drug carriers for effective drug delivery has been extensively used in both academic and industrial research and development. This new type of composite materials frequently displays considerable improvements of material properties when compared to the matrix solid alone, or to conventional microcomposites. These outstanding characterisitcs include mechanical properties, molecular permeability and the control of drug release, as well as properties related to engineering points of view, such as thermal stability, chemical resistance, surface appearance, electrical conductivity, and optical clarity. The controlled release of drugs from nanocomposite systems aims at their delivery at optimum amount for long periods, at increasing the efficacy of the drug, and at improving patient satisfaction. This review paper has been discussed to introduce some nanocomposite systems and to state their application for drug delivery.

controlled drug is a process where a carrier has an account with medication can be combined to form the active drug in the body operating the preset desired from this article be abandoned and, therefore, the optimization of the release drug is of special importance. In the present study, Curcumin drug release based on statistical methods that include response surface curve and the method of multivariate modeling can be hard to check, and then optimize the results of drug release both methods can be compared and demonstrated that although the model obtained from the level of responses to experimental, but because the taking effect of the invoices is capable of simultaneously the amount of drug in release Effective factor values that measure has not yet been done as well as anticipated. In addition it's possible to calculate the effect of each factor and higher power in the process of release reviewed.