Emulsion Cross-linking Method Research Articles

Tannic acid-crosslinked gelatin composite microspheres adsorbed with CQAS or Ca2+ for rapid hemostasis

In the case of massive blood loss due to natural disasters and wars, timely and rapid hemostasis is of great significance to improve the survival rate of injured people. Nevertheless, uncontrolled, noncompressible, and irregular bleeding wounds remain a giant challenge for rapid hemostasis. In this study, the tannic acid-crosslinked gelatin was first obtained by Michael addition reaction, and then the tannic acid-crosslinked gelatin composite microspheres (TGMs) were prepared by the emulsion cross-linking method. TGMs could significantly improve the water absorption and hemostatic performance compared with single component gelatin microspheres (GMs). Increasing the water absorption ratio and introducing blood coagulation factors into composite materials are simple and effective strategies to enhance the hemostatic properties. Therefore, chitosan quaternary ammonium salt (CQAS) and Ca2+ were electrostatic adsorbed to obtain two kinds of functional TGMs, which were respectively CQAS-absorbed TGMs (T2GMs-CQAS) and calcium ion-absorbed TGMs (T2GMs-Ca2+). Notably, T2GMs-CQAS, and T2GMs-Ca2+ could absorb water rapidly within 3seconds, in addition, especially the water absorption ratio of T2GMs-CQAS could reach 2.95 times compared with GMs. Benefited from rapid water absorption, coagulation pathway activation, and red blood cells aggregation of T2GMs-CQAS and T2GMs-Ca2+, resulting in rapid blood coagulation in vitro. In addition, CQAS and Ca2+ provided strong and intrinsic antibacterial activity due to positive charge. Moreover, in the tail amputation and liver hemostatic models, T2GMs-CQAS and T2GMs-Ca2+ demonstrated superior hemostatic effects compared to commercial Yunnan Baiyao®. In conclusion, T2GMs-CQAS and T2GMs-Ca2+ have potential applications as hemostatic dressings in uncontrolled, noncompressible, and irregular bleeding wounds.

Preparation, characterisation, pharmacokinetics and distribution of esculin microspheres administered via intravitreal injection into rabbit brain

This study explored the distribution of esculin microspheres in rabbit brain tissue following intravitreal injection and investigated the possibility of direct entry of the drug into the brain through the eye, to develop a formulation with enhanced therapeutic efficacy against Parkinson’s disease. Chitosan microspheres of esculin were prepared via an emulsification cross-linking method and their characteristics were evaluated, including angle of repose, bulk density, and swelling ratio. Furthermore, the pharmacokinetic parameters and brain tissue distribution in rabbits were compared among groups administered esculin eye drops, intravitreal esculin solution, and intravitreal esculin microspheres, to determine whether esculin could enter the brain through an ocular route. The results showed that the prepared esculin microspheres were spherical and had good fluidity. Notably, intravitreal administration enhanced the area under the curve (AUC) of esculin in the thalamus. Delivery through microspheres prolonged the drug retention time in both rabbit plasma and brain tissues, as well as the brain-targeting efficiency of esculin. The collective findings indicated that there may be a direct eye-brain pathway facilitating enter of esculin microspheres into brain tissue after intravitreal injection, supporting the utility of intravitreal esculin microspheres as an effective therapeutic formulation for Parkinson’s disease, a long-term chronic condition.

Hydrogel microspheres based on Bletilla striata polysaccharide as a promising cervical positioning drug delivery system

Due to female cervical mucosa is smooth and covered with a mucous layer, so the spreadability and mucoadhesion are crucial for the development of cervical positioning drug delivery system (CPDDS). In this work, the natural polymer Bletilla striata polysaccharide (BSP) as a hydrogel matrix-forming material was used for the preparing of hydrogel microspheres (HMs) by an improved emulsion crosslinking method. The prepared HMs have a spherical or quasi-spherical shape with a size of 115 ± 27 μm, resulting a good fluidity for spreading well at the administration site. By the physical entanglements of hydrophilic polymer chains of BSP, the matrix of HMs presents a microporous structure. With microporous matrix, the HMs could absorb water from mucous layer and achieve an optimum hydration required for mucoadhesion when they contact the cervical mucosa, also could keep their mucoadhesion behavior and morphology for a long time even after absorbing more water. As a result, the cervical positioning drug release behavior and long retention time at the cervical mucosa obtained. The loaded drug release profile of HMs include a low initial burst release and subsequent a longer sustained release, this is beneficial for the local treatment of cervical diseases. Owing to the BSP is a natural biodegradable polymer, the HMs have better biocompatibility with mucosal tissues and without causing irritation. In conclusion, this work suggest that the HMs based on BSP polymer is a promising CPDDS for clinical applications.

Preparation and Evaluation of Chitosan Microspheres Containing Levofloxacin

Objectives: The objective of present study was to develop chitosan-based sustained release Levofloxacin microspheres to reduce the dosing frequency. Materials and Methods: The Levofloxacin -loaded microspheres were prepared by emulsification cross-linking method using glutaraldehyde as cross-linking agent. Accurately weighed quantity of Chitosan was dissolved in 1% (v/v) aqueous acetic acid. Results: The percentage yield of the emulsification cross-linking method was determined to be between 74 and 81.5 percent, and the spherical microspheres had particle sizes ranging from 2 m to 200 m. According to the in vitro dissolution analysis of the improved formulation (F2) (table 7.8), when the medication was enclosed in Chitosan microspheres, 95 percent of the formulation was released after 12 hours, demonstrating that the drug is released from the formulation in a controlled way. Conclusions: The percentage of entrapment effectiveness, particle size, and percentage of drug release were significantly impacted by the drug: polymer ratio and GA volume. According to research using scanning electron microscopy (SEM), microspheres were round and had a smooth surface. Nicorandil-loaded chitosan microsphere formulations released their drugs via fickian diffusion.

The effective removal of Congo red dye via chitosan-layered double hydroxide composite and the deep insight into mechanism

In this study, the chitosan microspheres (CSM) were successfully prepared by emulsion crosslinking method, and layered double hydroxides (LDH) was grown in situ on the surface of the chitosan microspheres to prepare chitosan-layered double hydroxide composites (CS@LDH). The properties of CS@LDH composites were characterized by means of SEM, XRD, FT-IR and EDS. The removal effect of the composite on Congo red (CR) dye was studied. The batch adsorption experiments indicated that chitosan intercalated LDH obtained better adsorption capacity for CR than CSM and LDH, the equilibrium adsorption capacity of CS@LDH, CSM and LDH was 745.8, 285.5 and 226.4mg g−1, respectively. The results of adsorption dynamics and isotherm models showed that the adsorption process was more consistent with Elovich nonlinear model and Temkin isotherm model. The characterization of CS@LDH after adsorption of CR implied that the affinity between CS@LDH and CR mainly involved electrostatic interaction was revealed via Independent Gradient Model based on the Hirshfeld partition of molecular density (IGMH) and Hirshfeld surface analysis. In addition, molecular dynamics (MD) simulations were conducted to analyze the influence of CS@LDH on the structure and properties of CR. The results indicate a significant adsorption effect of CS@LDH on CR.

Formulation and Characterization of Blend Microspheres of Anti Diabetic Drug Glimepiride

The objective of the present investigation was to prepare polymeric blend microspheres of glimepiride for improving its half-life using chitosan and gelatin as the two polymers for preparing the blend. The blend microspheres of chitosan and gelatin were prepared by using different ratios of both the polymers as well as cross-linking agent, glutaraldehyde (GA), by emulsion cross-linking method. The optimum formulation was one which exhibited the lowest particles size and it was used to load glimepiride (20% by weight) of the polymers. The glimepiride loaded blend microspheres were evaluated for yield, drug polymer interaction, entrapment efficiency, surface study and in vitro release. The particle size of the blend microspheres was found to be in the range of 126.8 µm to 371.3 µm. The lowest particle size (126.8 ± 6.11 µm) was obtained in AF5 containing 50% of gelatin and 50% of chitosan. The FTIR spectra of the physical mixture of glimepiride, gelatin and chitosan displayed all the characteristic peaks of glimepiride, thus indicating that no incompatibility was present between the drug and the polymer. The SEM image of the drug loaded blend microsphere revealed spherical particles of irregular size with smooth surface. The average particles size of the glimepiride loaded blend microspheres was obtained to be 131.4 ± 9.7 µm with a yield of 91.6% by weight of the drug and polymers used for formulation of the microspheres. It was found that 82.4 ± 6.8% of glimepiride was found to be entrapped in the particles. The results of the in vitro release studies of the glimepiride loaded blend microsphere revealed that 71.49 ± 0.74 % glimepiride was released from the particles at the end of 12th hour of study.

In vitro 5-fluorouracil release properties investigation from pH sensitive sodium alginate coated and uncoated methyl cellulose/chitosan microspheres

5-Fluorouracil (5-FU) has been in clinical practice for decades one of the oldest chemotherapy agents. However, intravenous administration of 5-FU requires the development of an oral controlled delivery system for improved patient compliances. For this purpose, 5-FU loaded and sodium alginate (NaAlg) coated and uncoated methyl cellulose (MC)/chitosan (CS) microspheres were prepared by emulsion crosslinking method using a mixture of water and oil. Firstly, MC/CS microspheres were prepared and then coated with NaAlg. The prepared microspheres were characterized by optical microscopy, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Microspheres were also characterized by equilibrium swelling values and drug release profiles. The in vitro drug release studies were carried out with three pH values 1.2, 6.8, and 7.4, respectively, each for 2 h. It was determined that coating the microspheres with NaAlg provides more controlled drug release, especially at pH 1.2. The effects of the preparation conditions, such as coating time, MC/CS ratio, NaAlg concentration, and crosslinker concentration on the 5-FU release were investigated.

Formulation And Evaluation Of Biodegradable Microsphere Hydrogel For Ocular Delivery Of Ofloxacin

The objective of the present investigation was to explore the hydrogel microspheres loaded with Ofloxacin to obtain controlled release for ocular delivery. The FTIR spectra of pure drug and the drug excipient mixture revealed no chemical interaction. Ofloxacin loaded hydrogel microspheres were prepared using Chitosan/Pluronic F127 blend and emulsion crosslinking method. F7 with blend ratio 3.33:1 exhibited the highest encapsulation efficiency (77.85%) whereas the lowest encapsulation was witnesses in the formulation F3 (32.10%) which has a blend ratio of 15:1. The particle size ranged from 29.3 µm for F3 to 146.5 µm for F7. The microspheres exhibited negative zeta potential and the value was found to be -17.5mV for F7. F3 exhibited the highest water uptake (316.0 %) whereas F7 exhibited the lowest water uptake (81.0 %). F7 released around 58.4% drug after 24 h. Hence F7 was considered to be the most optimized formulation. The release of Ofloxacin from F7 followed Higuchi mathematical model suggesting Non-Fickian diffusion.

Quality by Design-driven Development of 5-fluorouracil Loaded Mucoadhesive Microparticulate Drug Delivery Systems for Effective Chemotherapy for Colorectal Cancer

Aims: To enhance oral bioavailability and decrease the dosing frequency of 5-Fluorouracil Background: Cancer is one of the most dreadful diseases for which complete cures are not possible, but colorectal cancer is completely curable if diagnosed at an early stage. If diagnosed in late-stage, 5-Fluorouracil (5-FU) is mostly recommended for its effective treatment, but the challenges associated with this drug are short elimination half-life, severe side effects, as well as non-specificity. The challenges can be better addressed by fabricating microbeads using the QbD approach. To enhance the oral bioavailability of 5-FU and to target the colon for the effective treatment of colorectal cancer, the microbeads were fabricated by emulsification crosslinking method using Box-Behnken design. Objective: To target the colon for effective treatment of colorectal cancer with enhanced oral bioavailability. Methods: The microparticulate drug delivery system was fabricated by using the emulsification crosslinking method by implementing a quality design approach with risk assessment followed by characterization such as FTIR, DSC, TGA, XRD, in vitro drug release, in vitro cytotoxicity study and in vivo pharmacokinetic studies. Results: The patient-centric quality target product profile (QTPP) was set. QTPP inspired critical quality attributes (CQAs) were searched out. The critical material attributes (CMAs) and critical process parameters (CPPs) influencing CQAs were distinguished. The seventeen formulations were fabricated employing Box Behnken Design, followed by optimization using numerical and graphical optimization techniques and the optimized microbeads were subjected to in vivo pharmacokinetic and in vitro cytotoxicity studies using HT 29 cell lines. The results revealed that 5-FU-loaded microbeads exhibited significantly more cytotoxic, and bioavailability was found to be nearly doubled as compared to pure drugs. Conclusion: 5-FU-loaded microbeads can be developed and optimized successfully by using quality by design approach and coating with eudragit S100, which can be targeted to the colon for the effective treatment of colorectal cancer.

Preparation and properties of gelatin-tannic acid histidine metal complex microspheres

Tannin histidine metal complex is a type of synthetic analogues of superoxide dismutase. To make the most of its SOD-like activity and expand its value in medical field, the gelatin-tannic acid histidine metal complex microspheres were prepared by emulsion cross-linking method. The optimum conditions for preparation of microspheres are found based on encapsulation ratio and the encapsulation efficiency range of four types of complex microspheres is 89.90–93.57 % under these conditions. The microspheres were characterized by IF spectrum, SEM and particle size analysis. The results showed that the average particle size of the four kinds of microspheres ranged from 5.5 to 14.7 μm. Certain properties of microspheres were investigated and results prove that they have a high antioxidant property and a good sustained release effect, meanwhile, the optimal storage temperature and stable kinetic model are obtained. The study provides a way for the application of superoxide dismutase mimics in the sustained release.

Preparation of a modified silk-based gel/microsphere composite as a potential hepatic arterial embolization agent

Transcatheter arterial chemoembolization (TACE) is an effective method for treating hepatocellular carcinoma (HCC). In this study, chitosan (CS), sodium glycerophosphate (GP), and sodium alginate (SA) were used as the main raw materials to develop clinically non-degradable embolization microspheres (Ms). Chitosan/sodium alginate embolization Ms. were generated using an emulsification cross-linking method. The Ms. were then uniformly dispersed in CS/GP temperature-sensitive gels to produce Gel/Ms. composite embolic agents. The results showed that Gel/Ms. had good morphology and a neatly arranged three-dimensional structure, and the Ms. dispersed in the Gel as evidenced by SEM. Furthermore, Gel/Ms. has good blood compatibility, with a hemolysis rate of ≤5 %. The cytotoxicity experiments have also proven its excellent cell compatibility. The degradation rate of Gel/Ms. was 58.869 ± 1.754 % within 4 weeks, indicating that Gel/Ms. had good degradation performance matching its drug release purpose. The Gel/Ms. adheres better at the target site than Ms. alone and releases the drug steadily over a long period, and the maximum release rate of Gel/Ms. within 8 h was 38.33 ± 1.528 %, and within 168 h was 81.266 ± 1.193 %. Overall, Gel/Ms. demonstrate better slow drug release, reduced sudden drug release, prolonged drug action time at the target site, and reduced toxic side effects on the body compared to Gel alone.

Preparation of drug-loaded chitosan microspheres repair materials.

With the development of society and the progress of science and technology, microspheres, as a new polymer material, have been applied to all aspects of human beings. Microspheres can play a huge role in food safety, electronic technology, sewage treatment, biomedicine, etc., and are non-toxic or harmless. There are three main types of substrates for the preparation of microspheres: natural polymers, semi-synthetic polymer materials, and synthetic polymer materials. In this study, the inorganic material kaolin was modified by the emulsification-crosslinking method with chitosan and composite microspheres with large interlayer spacing were prepared, which were characterized by Fourier Transform Ioncyclotron Resonancel (FTIR) analysis and Scanning Electron Microscope (SEM). The prepared kaolin/chitosan microspheres were then placed in different amounts of aspirin and the optimal dose was investigated by encapsulation efficiency and drug loading rate. The drug release rate of 0.5 h, 1 h, 1.5 h, 2 h, 4 h, 6 h, and 12 h was then determined by simulating the human colon to determine the performance of the sustained-release drug. The experimental results showed that after the prepared composite microspheres were loaded with aspirin drug, we got the optimal dosage of 0.1 g by discussing the encapsulation efficiency and drug loading rate of the drug-loaded microspheres, and the encapsulation efficiency reached 80.80%, while the drug loading rate was 24.40%, the drug release capacity reached about 83% in about 12 hours. The research shows that the kaolin/chitosan drug-loaded microspheres prepared by the emulsification and cross-linking method are excellent drug-loading materials.

Design, Optimization and Characterization of Metformin Hydrochloride Loaded Biodegradable Microspheres using Box Behnken design for Local Delivery in Periodontitis

In the present study, metformin hydrochloride-loaded microspheres were prepared for filling into the periodontal pockets with or without grafts for the treatment of periodontitis. For this purpose, chitosan was chosen as a polymer and used at different drug/polymer ratios in the preparation of microspheres by emulsion cross-linking method. Optimization was carried out by implementing a three-factor, three-level Box–Behnken design. Mathematical models were generated by regression analysis for responses of particle size (PS) and entrapment efficiency (EE). The experimental design took into account the preparation of optimized formulation with maximum %EE and minimum PS at optimum process conditions for the microsphere formulation by reducing chemical use and formulation time, in an economical way. The optimized formulation was selected on the basis of the desirability function and was further evaluated with respect to the particle size, entrapment efficiency, in-vitro drug release, differential scanning calorimetry (DSC), fourier transform infrared (FTIR) spectroscopy and surface morphology studies. The results of release studies were evaluated kinetically and statistically. Particle size and entrapment efficiency of the selected batch were found to be in the range of 40.2 to 59.6 μm and 85 to 95%, respectively. The DSC studies revealed molecular dispersion and conversion of the drug into an amorphous form. Surface morphology of microspheres was analyzed by scanning electron microscopy (SEM) and found to be spherical in shape with a smooth surface. The mean particle size, EE, and in-vitro drug release of the optimized batch were found to be 51.4 ± 4.8 μm, 96.5 ± 1.42%, and 79.8 ± 3.1%, respectively. The release kinetics showed that the release followed the Peppas model, and the main mechanism of drug release was diffusion. These sustained-release chitosan microspheres could be a promising drug delivery system for local delivery of metformin hydrochloride in the treatment of periodontitis.

Bone marrow mesenchymal stem cells response on collagen/hyaluronan/chondroitin scaffold enriched with gentamicin -loaded gelatin microparticles for skin tissue engineering.

The repair and functional reconstruction of large skin defects caused by burn remains an intractable clinical problem. Collagen type I (ColI) was extracted from carp scales and confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis ultraviolet adsorption spectra and automatic amino acid analyzer. Then the scaffolds containing the purified ColI, hyaluronic acid (HA) and chondroitin sulfate (CS) were constructed and examined. The results showed that the scaffold (ColI:CS:HA=9:1:1) had larger pore diameter, porosity, water absorption, degradation rate and tensile strength. gentamycin sulphate (GS) - gelatin microspheres (GMSs) were prepared by emulsion cross-linking method. The drug release study of the ColI-CS-HA-GS/GMSs scaffold with antibacterial property showed a prolonged, continuous, and sustained release of GS. The bone marrow mesenchymal stem cells (BMSCs) were extracted from rat and inoculated into the ColI-HA-CS-GS/GMSs scaffold. The results performed that the scaffold could accelerate proliferation of the BMSCs and wound healing.

Formulation and Evaluation of Oral Mucoadhesive Microspheres of Ofloxacin for Peptic Ulcer Use

A peptic ulcer is a disease that affects the stomach lining caused by Helicobacter pylori. The present research aimed to formulate and evaluate the mucoadhesive microsphere of ofloxacin for the effective and safe treatment of peptic ulcers. The mucoadhesive microspheres were developed using natural polymers like Guar gum, Sodium alginate, and Chitosan using the emulsification cross-linking method. A total of 8 batch formulations were prepared using 23 full factorial designs. The prepared microspheres were evaluated various parameters such as % yield, entrapment efficiency, drug release study, in vitro wash-off test, optimization was done by the design of expert which was further subjected to statistical analysis that was kinetic release mechanism, compatibility studies were performed such as FTIR and DSC. Using factorial design 23 for the maximum possible formulation, the optimized formulation was found to be F5 in terms of better release for a longer time and with better mucoadhesive properties on the use of guar gum, sodium alginate, and chitosan in ratio 1:1:2. Second-order polynomial equations were derived for absorbing responses after the application of ANOVA, after omitting the non-significant (p ≥ 0.05) coefficients. %CDR 56.10 % for an extended period of 8 h, % EE exhibited 86.25±1.16. The sustained release activity of F5 might be due to the adhesion of the polymer to the gastric mucosa for more extended periods of 71 % to 8 h. it is also favoured by the suitable particle size of the optimized formulation. The result indicated that the prepared mucoadhesive microspheres can release the ofloxacin in sustained manner and helps in the management of peptic ulcer. HIGHLIGHTS Ofloxacin loaded mucoadhesive microsphere was prepared for treatment of peptic ulcer The mucoadhesive microspheres were developed using natural polymers A total of 8 batch formulations were prepared using 23 full factorial designs Drug release from the optimized microsphere was 71 % to 8 h The developed microsphere can effectively deliver the drug in stomach part GRAPHICAL ABSTRACT

Adriamycin-loaded Gelatin Microspheres in the Treatment of Bone Tumors

Objective: This study harnessed adriamycin-loaded gelatin microspheres (ADM-GMS) to examine their properties and in vitro release characteristics, and explore their effect on human osteosarcoma U-20s cell strain and its mechanism. Methods: ADM-GMS was prepared using the emulsification-crosslinking method. The scanning electron microscope was employed to observe the shape of microspheres, and particle size and distribution were measured using a laser particle size device. The drug loading rate and encapsulation rate were calculated by ultraviolet spectrophotometry, and the drug release performance of the microspheres to adriamycin (ADM) was evaluated. The cell counting kit-8 (CCK-8) method was used to evaluate the anti-tumor activity of ADM-GMS on human osteosarcoma U-20s cell strain in vitro. Results: We determined an optimal material ratio of 1:10 for ADM-GMS, with which the microspheres showed a round shape and excellent dispersity. The average particle size with the optimal material ratio was 14.02±1.67μm, with a drug loading rate of 6.05±0.26% and an encapsulation rate of 84.27±3.10%. ADM-GMS had excellent sustained-release properties and a significant inhibitory effect on the growth of human osteosarcoma U-20s. Conclusion: ADM-GMS, prepared with a material ratio of 1:1, has a promising slow-release ability and an anti-bone tumor effect with a lower Semi-inhibitory concentration. Thus, this ADM gelatin delivery system is worthy of further clinical research. However, the detection method in this study is simple and weakly supported by clinical trials, and more investigations are required for further verification.

NICORANDIL MUCOADHESIVE MICROSPHERES: FORMULATION DEVELOPMENT, PHYSICO-CHEMICAL AND FUNCTIONAL CHARACTERIZATION

Objective: The study aims to prepare and evaluate Nicorandil mucoadhesive microspheres to improve the oral physicochemical properties of nicorandil and mucoadhesion to extend the residence time at the absorption site. Methods: Nicorandil mucoadhesive microsphere was prepared by emulsion cross-linking method using fenugreek gum, karaya gum as polymer, and glutaraldehyde as a cross-linking agent. Drug entrapment efficiency, particle size, % swelling index, mucoadhesion study, differential scanning calorimetry, powder x-ray diffraction, Fourier transform infrared spectroscopy, and in vitro dissolution studies were used to characterize the microspheres. Results: The characterization studies indicated the formation of mucoadhesive microspheres. The nicorandil mucoadhesive microspheres particle size is130.83±0.48, entrapment efficiency 66.91±0.54, swelling index 82.69±0.40, % mucoadhesion 95.22±0.13 and in vitro drug release was found to be 89.96±0.17 % at the end of 12 h. Conclusion: This research work successfully formed nicorandil mucoadhesive microspheres formulation using the emulsion cross-linking method. Encapsulation efficiency and other physicochemical and functional characterization of microspheres suggested the successful formation of nicorandil mucoadhesive microspheres.

Synthesis of microcapsules containing a formaldehyde scavenger for the sustainable control of hazardous chemical release from particleboard.

Formaldehyde scavenger microcapsules were introduced into particleboard to prepare an ecofriendly particleboard with a low pollution release in response to the problem of long-term unstable free formaldehyde release from particleboards. By analyzing key parameters of formaldehyde emission from particleboard, the effects of microcapsules on the diffusion, migration and inhibition of free formaldehyde in particleboard pore structures was discussed. The results showed that microencapsulated formaldehyde scavenger prepared by an emulsification cross-linking method with chitosan as the wall material and urea as the core material resulted in a good long-term controlled release effect on formaldehyde emission. Compared with that of the control panel, the formaldehyde emission of the particleboard with microcapsules decreased by 51.4 % and 25.8 % at 28 d and 180 d, respectively. The addition of formaldehyde scavenger microcapsules increased the particleboard macroscopic pore volume, which facilitated the conversion of adsorbed formaldehyde into free formaldehyde in the pore structure, thereby promoting its migration and diffusion in the particleboard pores. Moreover, the synergistic effect of the addition-condensation and nucleophilic cross-linking of the core and wall materials quickly captured the free formaldehyde in the panels and reduced the releasable concentration of formaldehyde in the material, thus achieving the long-term effective control of formaldehyde emission.

Multifunctional magnetocaloric bone cement with a time-varying alkaline microenvironment for sequential bacterial inhibition, angiogenesis and osteogenesis.

Repairing infected bone defects remains a severe challenge due to antibiotic abuse and recurrence. Hence, we modified magnetocaloric Fe3O4 nanoparticles and added them to magnesium calcium phosphate bone cement (MCPC) to fabricate multifunctional magnetic composites for sequential bacterial inhibition, angiogenesis and osteogenesis. Nevertheless, high doses of Mg ions and Fe ions were released from MCPC, which adversely affected osteogenesis. Thus, Fe3O4 was modified using gelatin according to the emulsification crosslinking method, which exhibited a controllable magnetocaloric effect and degradation behavior, and favorable anti-bacterial ability under the action of an alternating magnetic field (AMF). In the early stage, the residual MgO created a local strong alkaline microenvironment by hydrolysis, which inhibited the function and activity of S. aureus and E. coli. At the later stage, the MCPC composites were controllably degraded under the function of gelatin and maintained a long-term local slight alkaline microenvironment that promoted the osteogenic differentiation and mineralization of BMSCs. In vivo subcutaneous implantation experiments further indicated that MCPC composites showed good biocompatibility and facilitated angiogenesis, presenting a promising future in magnetic materials design and infectious bone defect repair.

Sustainable material for urea delivery based on chitosan cross-linked by glutaraldehyde saturated toluene: Characterization and determination of the release rate mathematical model

The aims of this study were to characterize the urea-loaded chitosan microspheres and determine the release kinetic constants and diffusion coefficients. An emulsion cross-linking method was used to prepare the urea-loaded chitosan microspheres. Urea was dissolved in a solution of chitosan then put into vegetable oil and stirred to form an emulsion. Glutaraldehyde saturated toluene (GST) was added into the emulsion dropwise while continuously stirring for the solidification process. Chitosan microspheres filled with urea were washed, dried, and then analyzed. Characterization of the urea-loaded chitosan microspheres was conducted using a scanning electron microscope (SEM), Raman spectroscopy, X-ray diffraction, and particle size distribution. The cumulative release analysis was used to determine the amount of urea released from the chitosan microspheres and determine the release kinetic constants and diffusion coefficients. The chitosan microspheres had a good spherical geometry with a smooth surface and crystallinity of 95.5 - 98.18%. They had a diameter in the range of 125.31 - 153.65 m and a cumulative release value in the range of 38.22 - 48.06%. Based on the kinetic analysis, the best kinetic models were models of Korsmeyer-Peppas, Peppas-Sahlin, and simple power law with the burst effect resulting in the highest R2 of 0.99. The diffusion coefficient obtained was in the range of 5.439 × 10-11 - 7.512 × 10-11 cm2/sec.