Synthesis of Novel Chitosan Microspheres Grafted with β-Cyclodextrins and Their Adsorption for Iodine for Antibacterial Activities

The novel chitosan microspheres grafted with beta-cyclodextrins (CMGC) wereprepared by means of the reaction of chitosan microspheres and mono-(6-p-tosyl)- beta-cyclodextrins(beta-CD-OTs-6). beta-CD-OTs-6 were gained by the reaction of p-toluenesul-fonyl chloride (TsCl) andbeta-cyclodextrins (beta-CDs). Their structures were proved by Fourier transform infrared spectralanalysis (FT-IR), X ray powder diffraction analysis, and ^(13)C NMR; the configuration of CMGC wascharacterized by scanning electron micrograph (SEM) and transmittance electron micrograph (TEM). Theinclusion complex of CMGC with iodine was prepared and its inclusion ability was studied. Theexperimental results showed that some iodine was included with CMGC and formed a stable inclusion.The stable complex of CMGC and iodine (CMGC-1) shows good antibacterial effect.

Fabrication of chitosan microspheres for efficient adsorption of methyl orange

In this article, morphology, structure and size controllable chitosan microspheres with high mechanical strength were synthesized by microfluidic technology combining chemical crosslinking and used as an adsorbent for methyl orange. The synthesized adsorbents were characterized using scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR), and an Energy Dispersive Spectrometer(EDS). The effect of pH revealed that the adsorption process depended on pH and the pH variation of methyl orange solution after adsorption indicated that adsorption capacity was affected through the associated role of chitosan nature and pH variation. Experimental results suggested that the as-prepared chitosan microspheres were controlled within a narrow size distribution(coefficients of variation is 1.81%), whose adsorption capacity reached to 207 mg·g^(-1) and mechanical strength was suitable to resist forces. In addition, the adsorption isotherm was well fitted with the Langmuir model, and the adsorption kinetic was best described by the pseudo-second-order kinetic model.The high performance microfluidic-synthesized chitosan microspheres have promising potentials in the applications of removing dyes from wastewater.

Relationship between breakthrough curve and adsorption isotherm of Ca(Ⅱ)imprinted chitosan microspheres for metal adsorption

In this work, an equilibrium-dispersion model was successfully established to describe the breakthrough performance of Ca（Ⅱ） imprinted chitosan （Ca（Ⅱ）-CS） microspheres packed column for metal adsorption, and the assumptions of Langmuir isotherms and axial dispersion controlled mass transfer process were confirmed. The axial dispersion coefficient in Ca（Ⅱ）-CS microspheres packed column was found to be almost proportional to the linear velocity and fit for prediction through single breakthrough test. Sensitivity analysis for breakthrough curve indicated the axial dispersion coefficient as well as Langmuir coefficient was sensitive variable for deep removal requirement. The retrieval of the adsorption isotherms of Ca（Ⅱ）-CS microspheres from breakthrough curve was fulfilled by modelling calibration. A strategy based on the correlation between adsorption isotherms and breakthrough performance was further proposed to simplify the column adsorption design using absorbents with small/uniform size and fast adsorption kinetics like Ca（Ⅱ）-CS microspheres to cut down the gap between lab and industry.

Preparation and Characterization of Chitosan Microsphere Loading Bovine Serum Albumin

To optimize the preparation process of chitosan microspheres and study its loading capacity, chitosan microsphere was prepared by crosslinking with glutaraldehyde, and bovine serum albumin （BSA） was absorbed onto chitosan microsphere. Scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FITR）, TA instruments and zeta potentiometer analyzer were used to characterize the parameters with respect to size, thermal characters, morphology, and zeta potential of the microspheres. The loading capability and in vitro release tests were carried out. The results showed that chitosan microsphere with particle size less than 10 μm and positively charged （＋25.97±0.56 mV） can be obtained under the aldehyde group to amino group ratio at 1：1. A loading capacity of BSA at 28.63±0.15 g/100 g with corresponding loading efficiency at 72.01±1.44% was obtained for chitosan microsphere. In vitro test revealed a burst release followed by sustained-release profile.

Preparation and properties of calcium sulfate bone cement incorporated with silk fibroin and Sema3A-Ioaded chitosan microspheres

To search for new bioactive materials which can be used as the substitute of bone repairing and drug carriers, Sema3A-Ioaded chitosan microspheres （SLCM） and silk fibroin （SF） were mixed with calcium sulfate cement （CSC）. SEM, particle size analysis and swelling rate determination were performed to study properties of the microspheres. The drug loading, encapsulation efficiency and drug release rate were determined by ELISA. Microspheres with different SLCM weight contents （0.5%, 1% and 5%） were prepared to determine which one has the strongest mechanical properties and the appropriate setting time. It was revealed that CSC/SF/0.5SLCM has satisfactory mechanical properties, and its in vitro biocompatibility was assessed by MTS. Chitosan microspheres （5-18 μm） were globular, the surface was smooth, and the swelling rate is （77.02 ± 5.57）%. With this formula, the setting time was increased with the addition of SLCM in CSCISF, and the cumulative drug release rate is 44.62% in 28 d. XRD results demonstrate that the main component is calcium sulfate. Also it was found that CSCiSFI 0.5SLCM supports the growth of MC3T3 cells. Thus the preparation of CSCISFIO.5SLCM was reliable, and the products had good structures, physical properties and biocompatibility, appearing to be a promising bone substitute material.

N self-doped multifunctional chitosan biochar-based microsphere with heterogeneous interfaces for self-powered supercapacitors to drive overall water splitting

Due to the rising need for clean and renewable energy,green materials including biochar are becoming increasingly popular in the field of energy storage and conversion.However,the lack of highly active and stable electrode materials hinders the development of stable energy supplies and efficient hydrogen production devices.Herein,we fabricated stable,conductive,and multifunctional chitosan microspheres by a facile emulsion crosslinking solution growth and hydrothermal sulphuration methods as multifunctional electrodes for overall water splitting driven by supercapacitors.This material possessed three-dimensional layered conductors with favorable heterojunction interface,ample hollow and porous structures.It presented remarkably enhanced electrochemical and catalytic activity for both supercapacitors and overall water electrolysis.The asymmetric supercapacitors based on chitosan biochar microsphere achieved high specific capacitance(260.9 F g^(−1) at 1 A g^(−1))and high energy density(81.5W h kg^(−1))at a power density of 978.4 W kg^(−1).The chitosan biochar microsphere as an electrode for electrolyze only required a low cell voltage of 1.49 V to reach a current density of 10 mA cm^(−2),and achieved excellent stability with 30 h continuous test at 20 mA cm^(−2).Then,we assembled a coupled energy storage device and hydrogen production system,the SCs as a backup power source availably guaranteed the continuous operation of overall water electrolysis.Our study provides valuable perspectives into the practical design of both integrated biochar-based electrode materials and coupled energy storage devices with energy conversion and storage in practical.

Microfluidic synthesis of thiourea modified chitosan microsphere of high specific surface area for heavy metal wastewater treatment

An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. Polyethylene glycol was used as a significant component added in aqueous solution of chitosan to produce such microspheres through droplets forming, chemical crosslinking and pores creating. For the improvement of adsorption capacity, thiourea was considered as an excellent choice in increasing amino functional group by graft modification. The SEM, FTIR and EDS were employed to detect distinct features of TMCM. Copper（Ⅱ） was used to test the adsorption performance of TMCM. The experimental results indicated that TMCM exhibited higher adsorption capacity（q_e= 60.6 mg g_（-1）） and faster adsorption rate than that non-modified chitosan microsphere（NMCM）.The adsorption kinetic was described well by the pseudo-second order kinetic model, which suggested that chemical adsorption along with electrons transferring was dominant in adsorption process.

A sustained release of BMP2 in urine-derived stemcells enhances the osteogenic differentiation and the potential of bone regeneration

Cell-based tissue engineering is one of the optimistic approaches to replace current treatments for bone defects.Urine-derived stem cells(USCs)are obtained non-invasively and become one of the promising seed cells for bone regeneration.An injectable BMP2-releasing chitosan microspheres/type I collagen hydrogel(BMP2-CSM/Col I hydrogel)was fabricated.USCs proliferated in a time-dependent fashion,spread with good extension and interconnected with each other in different hydrogels both for 2D and 3D models.BMP2 was released in a sustained mode for more than 28 days.Sustained-released BMP2 increased the ALP activities and mineral depositions of USCs in 2D culture,and enhanced the expression of osteogenic genes and proteins in 3D culture.In vivo,the mixture of USCs and BMP2-CSM/Col I hydrogels effectively enhanced bone regeneration,and the ratio of new bone volume to total bone volume was 38%after 8weeks of implantation.Our results suggested that BMP2-CSM/Col I hydrogels promoted osteogenic differentiation of USCs in 2D and 3D culture in vitro and USCs provided a promising cell source for bone tissue engineering in vivo.As such,USCs-seeded hydrogel scaffolds are regarded as an alternative approach in the repair of bone defects.

Microfluidic synthesis of renewable biosorbent with highly comprehensive adsorption performance for copper （II）

A microsphere biosorbent with uniform size （CV = 1.52%）, controllable morphology and component, and high mechanical strength was synthesized from chitosan by microfluidic technology combining with chemical crosslinking and solvent extraction. This chitosan microsphere （CS-MS） was prepared with a two-step solidification process, which was acquired by drying for the enhancement of mechanical property in final. The adsorption behavior of CS-MS towards copper （II） and main influencing factors on adsorption performance were investigated by batch experiments. Kinetic data high-lighted dominant chemical bonding along with electrons transferring in adsorption process. Isothermal analysis indicated that adsorption capacity was relevant to the number of active site. All these explorations provided a new direction for preparing highly comprehensive performance sorbent used in heavy metal treatment via microfluidic technology.