Huali Nie

Removal of Cu2+ from aqueous solution by chitosan-coated magnetic nanoparticles modified with α-ketoglutaric acid.

Chitosan-coated magnetic nanoparticles (CCMNPs), modified with a biodegradable and eco-friendly biologic reagent, alpha-ketoglutaric acid (alpha-KA), was used as a magnetic nanoadsorbent to remove toxic Cu(2+) ions from aqueous solution. The prepared magnetic nanoadsorbents were characterized by FTIR, TEM, VSM, XRD, and EDS. Factors influencing the adsorption of Cu(2+), e.g., initial metal concentration, initial pH, contact time and adsorbent concentration were investigated. TEM images show that the dimension of multidispersed circular particles is about 30 nm and no marked aggregation occurs. VSM patterns indicate superparamagnetic properties of magnetic nanoadsorbents. EDS pictures confirm the presence of the Cu(2+) on the surface of magnetic nanoadsorbents. Equilibrium studies show that Cu(2+) adsorption data follow Langmuir model. The maximum adsorption capacity (q(max)) for Cu(2+) ions was estimated to be 96.15 mg/g, which was higher than that of pure CCMNPs. The desorption data show no significant desorption hysteresis occurred. In addition, the high stability and recovery capacity of the chitosan-coated magnetic nanoparticles modified with alpha-ketoglutaric acid (alpha-KA-CCMNPs) suggest that these novel magnetic nanoadsorbents have potential applications for removing Cu(2+) from wastewater.

Removal of Cu2+ from aqueous solution by adsorption onto a novel activated nylon-based membrane

A novel activated nylon-based membrane was prepared and applied as an adsorbent for the removal of Cu2+ from aqueous solutions. It involved three stages: (i) deposition of a chitosan layer that functionalized the nylon membrane, (ii) cross-linking with epichlorohydrin to stabilize the polymer layer and enabling grafting, and (iii) iminodiacetic acid grafting. SEM and EDX techniques were used to characterize the composition of the membranes. Dynamic adsorption experiments on membranes were carried out at various pH values, contact times, adsorption dosages and initial metal concentrations to determine optimum membrane adsorption properties. The adsorption isotherm relating to Cu2+ fitted the Langmuir equation and an adsorption equilibrium constant and adsorption capacity of 2.345x10(-3)mg/ml and 10.794mg/g were determined, respectively. The experimental data was analyzed using two adsorption kinetic models, pseudo-first-order and pseudo-second-order with the latter system providing the best fit. Finally complete regeneration of the activated nylon membrane was possible using 100mmol/l Na2EDTA.

Microencapsulation of tamoxifen: Application to cotton fabric

Tamoxifen microcapsules and drug loaded medicated fabrics were investigated. The microcapsules were prepared using a complex coacervation procedure involving gelatin B and acacia gum. The morphology, particle size, drug loading capacity and in vitro release characteristics of the drug microcapsules were optimized for coating tamoxifen microcapsules onto the cotton fabrics. Infrared (IR) spectra and SEM were used to characterize the medicated fabrics and air permeability and laundering testing were undertaken to determine the efficiency and effectiveness of the system. Results showed that optimum condition for the microcapsules was at drug/polymer ratio 1:4, polymer concentration 3%, and rate of stirring 1000 rpm. In vitro release assays demonstrated that the tamoxifen was liberated over 10h after an initial bust rate period. SEM images illustrated that the tamoxifen microcapsules were spherical in shape and were also tightly fixed on to the cotton fabrics fast. These observations demonstrate that we have designed and fabricated a medicated system that potentially could be applied within a transdermal drug delivery system and so act in a system for the treatment of breast cancer.

Optimization of adsorption conditions of papain on dye affinity membrane using response surface methodology.

The adsorption of papain on Reactive Blue 4 dye-ligand affinity membrane was investigated in a batch system. The combined effects of operating parameters such as initial pH, temperature, and initial papain concentration on the adsorption were analyzed using response surface methodology. The optimum adsorption conditions were determined as initial pH 7.05, temperature 39 degrees C, and initial papain concentration 11.0mg/ml. At optimum conditions, the adsorption capacity of dye-ligand affinity membrane for papain was found to be 27.85 mg/g after 120 min adsorption. The papain was purified 34.6-fold in a single step determined by fast protein liquid chromatography. More than 85% of the adsorbed papain was desorbed using 1.0M NaCl at pH 9.0 as the elution agent. The purification process showed that the dye-ligand immobilized composite membrane gave good separation of papain from aqueous solution.

Optimization of adsorption conditions of BSA on thermosensitive magnetic composite particles using response surface methodology.

Thermosensitive core-shell magnetic composite particles with a magnetic silica core and a rich poly (N-vinylcaprolactam) (PNVCL) shell layer were developed for studying the adsorption of bovine serum albumin (BSA) in a batch system. Various analytical and spectroscopic techniques including SEM, FT-IR, VSM and DSC were used to characterize the adsorbents prepared in this study. The combined effects of operating parameters such as initial temperature, pH and initial BSA concentration on the adsorption were analyzed using response surface methodology. The optimum conditions were 40°C, pH 4.68, and initial BSA concentration 2.0 mg/mL. Desorption experiments were conducted by altering the system temperature where a high recovery rate of protein was obtained. The separation process developed here indicates that the dual-responsive smart adsorbent could be an ideal candidate for the separation of protein.

Molecularly imprinted polymer based on MWCNT-QDs as fluorescent biomimetic sensor for specific recognition of target protein

A novel molecularly imprinted optosensing material based on multi-walled carbon nanotube-quantum dots (MWCNT-QDs) has been designed and synthesized for its high selectivity, sensitivity and specificity in the recognition of a target protein bovine serum albumin (BSA). Molecularly imprinted polymer coated MWCNT-QDs using BSA as the template (BMIP-coated MWCNT-QDs) exhibits a fast mass-transfer speed with a response time of 25min. It is found that the BSA as a target protein can significantly quench the luminescence of BMIP-coated MWCNT-QDs in a concentration-dependent manner that is best described by a Stern-Volmer equation. The KSV for BSA is much higher than bovine hemoglobin and lysozyme, implying a highly selective recognition of the BMIP-coated MWCNT-QDs to BSA. Under optimal conditions, the relative fluorescence intensity of BMIP-coated MWCNT-QDs decreases linearly with the increasing target protein BSA in the concentration range of 5.0×10(-7)-35.0×10(-7)M with a detection limit of 80nM.

Polyacrylonitrile fibers efficiently loaded with tamoxifen citrate using wet-spinning from co-dissolving solution.

Tamoxifen citrate (TAM)-loaded polyacrylonitrile (PAN) fibers were prepared using an improved wet-spinning technique. TAM was used as a model drug to evaluate the potential application of the loaded fiber system for drug delivery. PAN was first homogeneously dissolved in the N,N-dimethylacetamide (DMAc) solution containing TAM and then the co-dissolving solution was solidified to prepare the fibers using a wet-spinning method. Chemical, morphological and mechanical property characterizations were carried out, as well as the studies of the drug release properties. TAM was successfully encapsulated into a monofilament fiber, and this system was stable in terms of high loading capacity and effectiveness in release. The diameter of drug-loaded fiber was in the range of 40-60 microm. The best values of the tensile strength at 2.968 cN/dtex and breaking elongation at 14.9% of drug-loaded fibers were obtained when the drug loading content was 23.1 wt.%. These characteristics were suitable for the weaving process. The in vitro release experiment indicated that constant drug release from the fiber was observed for a long duration of time. Kinetic studies demonstrated that the system followed the Higuchi kinetics. These findings demonstrate that controlled release of drugs from PAN fibers could be potentially useful in drug delivery systems.

Comparison: Adsorption of papain using immobilized dye ligands on affinity membranes

Novel membranes that involve the immobilization of Reactive Red 120 or Reactive Brown 10 as dye ligands were prepared. These were used in the purification of papain from papaya powder extracts. Papain adsorption capacities for the Red 120 and Brown 10 membranes were 143.6 mg/g and 107.3mg/g, respectively. The effectiveness of adsorption was demonstrated by Freundlich isotherm proficiency. The enzyme was eluted from the respective dye membranes using 1.0M NaCl at pH 6.0 and yields of over 80% were found for the Red 120-CS (chitosan)-nylon membrane whereas only a 50% recovery was possible using the Brown 10-CS-nylon membranes. It is concluded that Red 120-CS-nylon membranes could play an active role in the separation and purification of papain from crude extracts. This system has the potential to be developed for the commercial isolation of the protein.

Controlled release from thermo-sensitive PNVCL-co-MAA electrospun nanofibers: The effects of hydrophilicity/hydrophobicity of a drug

The thermo-sensitive copolymer poly(N-vinylcaprolactam-co-methacrylic acid) (PNVCL-co-MAA) was synthesized by free radical polymerization and the resulting nanofibers were fabricated using an electrospinning process. The molecular weight of the copolymer was adjusted by varying the content of methacrylic acid (MAA) while keeping that of N-vinylcaprolactam (NVCL) constant. Hydrophilic captopril and hydrophobic ketoprofen were used as model drugs, and PNVCL-co-MAA nanofibers were used as the drug carrier to investigate the effects of drug on its release properties from nanofibers at different temperatures. The results showed that slow release over several hours was observed at 40°C (above the lower critical solution temperature (LCST) of PNVCL-co-MAA), while the drugs exhibited a burst release of several seconds at 20°C (below the LCST). Drug release slowed with increasing content of the hydrophobic monomer NVCL. The hydrophilic captopril was released at a higher rate than the hydrophobic ketoprofen. The drug release characteristics were dependent on the temperature, the portion of hydrophilic groups and hydrophobic groups in the copolymer and hydrophilicity/hydrophobicity of drug. Study on the mechanism of release showed that Korsmeyer-Peppas model as a major drug release mechanism. Given these results, the PNVCL-co-MAA copolymers are proposed to have useful applications in intellectual drug delivery systems.

Galactose functionalized injectable thermoresponsive microgels for sustained protein release

Novel galactose functionalized thermoresponsive injectable microgels, poly(N-isopropylacrylamide-co-6-O-vinyladipoyl-D-galactose) P(NIPAAm-co-VAGA), have been fabricated using a combination of enzymatic transesterification and emulsion copolymerization. The microgels exhibit reversible temperature-responsive behavior, which can be tuned by varying the monomer feed ratio. The lower critical solution temperatures (LCSTs) of the materials are close to body temperature and can result in a rapid thermal gelation at 37 °C. Field emission scanning electron microscopy showed the resultant microgels to have porous structures, and dynamic light scattering experiments indicated a dramatic reduction in particle size as solutions of the polymers are heated through the LCST. The polymers can be loaded with protein (bovine serum albumin; BSA), and in vitro studies showed that the BSA release kinetics depend upon the temperature and copolymer composition. Microgels based on P(NIPAAm-co-VAGA) could hence serve as candidates for site-specific sustained release drug delivery systems.