Preparation of novel molecularly imprinted magnetic graphene oxide and their application for quercetin determination.

In this work, quercetin (Que) molecular imprinted polymer (MIP) material decorated on magnetic graphene oxide (MGO) with high performance was prepared for the first time using a surface-imprinting technique. Magnetic graphene oxide was synthesized using the solvothermal route. Methacrylic acid (MAA) was used as functional monomer, ethylene glycol dimethyl acrylate (EGDMA) as cross-linker; Que. was used as template, for the decoration with MIP. The prepared nanocomposite was examined by different characterization methods including fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM). The adsorption performance was investigated. MGO-MIP was found to have high loading (369 mg g-1) and selective capacity making the nanomaterial more performant than previous similar reported nanomaterials. The determination of Que. was carried out by mean of magnetic solid phase extraction method coupled with high-performance liquid chromatography (HPLC) and the extraction conditions studies were also performed out. Under the optimized conditions, MGO-MIP showed great performance for the extraction, separation and determination of Que. in green tea and serum samples, compared to the flavonoid analogs luteolin (Lut) and rutin (Rut) in the same matrix samples.

Physicochemical characterization and determination of chloramphenicol residues and heavy metals in Algerian honeys.

The concentration of certain heavy metals in various foods (fruits, cereals, legumes, and bee products) produced in industrial and urban cities is increasing each year following industrial development. Quality of honey and its contamination by different polluting agents are related essentially to its production environment, or it can arise from beekeeping practices. In the present study, the determination of physicochemical properties: moisture, pH, total acidity, electric conductivity, hydroxymethylfurfural (HMF), sugars, and chloramphenicol (CAP) residues; the metal content by determination of two toxic metals levels: lead (Pb) and cadmium (Cd); and other trace elements: magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and nickel (Ni) in 23 different honey samples collected from North regions of Algeria were investigated. The physicochemical properties and the metal contents were found within the ranges established by the international standards. For the antibiotic residues, only four honey samples are contaminated by CAP. Metals were found in non-significant values and are in safety baseline levels for human consumption except Mg which exceed the limits. These results suggested that honey could be used as an indicator to detect contaminating agents from the environment since bees are excellent sentinels for assessing environmental contamination because of their physiological and biological characteristics.

Folic acid-conjugated chitosan oligosaccharide-magnetic halloysite nanotubes as a delivery system for camptothecin.

In this research, to achieve enhanced intracellular uptake of anticancer drug carriers for efficient chemotherapy, folic acid conjugated chitosan oligosaccharides assembled magnetic halloysite nanotubes (FA-COS/MHNTs) have been tailored as multitask drug delivery system towards camptothecin (CPT). Besides magnetic targeting, the nanocomposites have been reacted with folate complex in order to selectively target cancer cells over expressing the folic acid receptor. HNTs showed to have a high storage capacity of CPT. In vitro, the release results indicated that CPT outflow from the nanocarriers at pH 5 was much greater than that at both pH 6.8 and 7.4. MTT assays showed that the CPT-loaded nanocarriers exhibited stronger cell growth inhibitory against colon cancer cell. Furthermore, nanocarriers gained specificity to target cancer cells because of the enhanced cell uptake mediated by FA moiety and presence of COS. Therefore, the rational designed HNTs nanocarrier for chemotherapy drug showed great potential as tumor-targeted drug delivery carrier.

QbD approach by computer aided design and response surface methodology for molecularly imprinted polymer based on magnetic halloysite nanotubes for extraction of norfloxacin from real samples.

This article describes the development, optimization, and evaluation of a novel composite imprinted polymer, on the basis of magnetic halloysite nanotubes (MHNTs-MIPs) using "Quality by Design (QbD)" approach combining computer simulation and response surface methodology. Norfloxacin, methacrylic acid, and ethylene glycol dimethacrylate were used as template, functional monomer and cross-linker, respectively. As a comparison, two MHNTs-MIPs have been prepared with the most suitable functional monomer methacrylic acid (MAA) along with acrylamide (AM). To explain the adsorption behavior, adsorption kinetics and isotherms were studied. Magnetic halloysite nanotubes molecularly imprinted polymers prepared from MAA (MHNTs-MIP1) displayed a high adsorption capacity (349 µg mg-1) toward NOR. A magnetic imprinting solid phase extraction method coupled with high performance liquid chromatography (MHNTs-MISPE-HPLC-UV) was developed for the determination of NOR in serum and water samples, by applying MHNTs-MIP as a sorbent. The recoveries from 83.76% to 103.30% in water and from 90.46% to 99.78% in serum were obtained. Besides remarquable mechanical properties and specific recognition of MHNTs-MIP toward template molecule. It could be also collected and separated fastly by external magnetic field. Moreover, MHNTs-MIPs could be reused for several cycles with the recovery range from 83.25% to 100.96% for water sample and from 85.65% to 100.33% for serum sample. These analytical results of serum and water samples showed that the proposed method based on MHNTs-MIPs is applicable for fast and selective extraction of therapeutic agents from biological fluids and environmental water.