Emulsion Cross-linking Method Research Articles

Simvastatin-Loaded Chitosan Microspheres as a Biomaterial for Dentin Tissue Engineering.

In the present study, chitosan microspheres (MSCH) loaded with different concentrations of simvastatin (2%, 5%, and 10%) were synthesized as a biomaterial for dentin tissue engineering. The microspheres were prepared by emulsion crosslinking method, and simvastatin was incorporated during the process. The microspheres were then physicochemically and morphologically characterized. Scanning electron microscopy and infrared spectroscopy confirmed the spherical morphology of synthesized microspheres and the chemical incorporation of simvastatin into MSCH, respectively. UV-visible absorption confirmed the controlled and continuous release pattern of the drug. To mimic the clinical application invitro, the microspheres were applied onto three-dimensional (3D) cultures of human dental pulp cells (HDPCs). Cell viability, proliferation, and insitu-mineralized matrix deposition were evaluated. The results indicated no cytotoxic effects for all 3D cultures for all tested biomaterials, with cells being able to proliferate significantly over time. HDPCs showed a significant increase in the deposition of mineralization nodules when 3D cultures were in direct contact with chitosan microspheres in comparison to control; nevertheless, the highest expression was observed for MSCH encapsulated with 5% and 10% simvastatin, which was significantly higher than plain MSCH. Therefore, chitosan microsphere systems loaded with 5%-10% simvastatin provided the development of a controlled release system in bioactive dosages for dentin tissue engineering.

A development of a gelatin and sodium carboxymethyl cellulose hydrogel system for dual-release transdermal delivery of lidocaine hydrochloride

This study introduces a dual-release transdermal drug delivery system using a hydrogel matrix of cross-linked gelatin and sodium carboxymethyl cellulose (NaCMC). Designed for immediate drug release from microneedles (MNs) and sustained release from microcapsules (MCs), this system utilizes lidocaine hydrochloride as the model drug. The fabrication process involved casting the hydrogel into MN molds, with MCs embedded in the backing layer, establishing a dual-release mechanism. MCs of gelatin and NaCMC were prepared by emulsion-crosslinking method and using glutaraldehyde as a crosslinker. MCs ranged in size from 50 to 264 μm and exhibited the highest drug release in acidic environments, showcasing a pH-responsive nature. Drug loading efficiency reached 9.8 %, while encapsulation efficiency was 75.8 %. The MNs, which had a conical shape and strong mechanical properties, demonstrated excellent penetration capabilities. The in vitro release profile indicated an initial burst within 10 min, followed by sustained release over 240 min, in line with the Korsmeyer-Peppas model. Additionally, the system displayed significant antimicrobial properties and good biocompatibility, with cell viability exceeding 86 %. This confirms its potential as a safe and effective platform for transdermal drug delivery.

Nisin-loaded chitosan/sodium alginate microspheres enhance the antimicrobial efficacy of nisin against Staphylococcus aureus.

To develop and evaluate nisin-loaded chitosan/sodium alginate (CS/SA) microspheres as an improved antimicrobial delivery system targeting Staphylococcus aureus strains. The microspheres were prepared using a modified water-in-oil emulsion cross-linking method, resulting in spherical particles sized 1-8µm with a surface charge of -7.92±5.09mV, confirmed by scanning electron microscopy (SEM) and Zetasizer analysis. Encapsulation efficiency (EE) and loading capacity (LC) of nisin were 87.60%±0.43% and 1.99%±0.01%, respectively. In vitro release studies over 48 h indicated a controlled release pattern of nisin, described by the Korsmeyer-Peppas model, with higher release rates at 37°C and alkaline pH. Antimicrobial assays showed an enhanced efficacy of nisin-loaded CS/SA microspheres compared to free nisin, with minimum inhibitory concentration values reduced by 50%. Confocal laser scanning microscopy (CLSM), SEM, and transmission electron microscopy showed significant bacterial membrane damage and cellular disruption induced by the microspheres. This study highlights the potential of nisin-loaded CS/SA microspheres as an innovative antimicrobial delivery system with improved stability and antimicrobial efficacy against S. aureus, addressing limitations associated with nisin applied alone.

Enhanced CO2 Capture Potential of Chitosan-Based Composite Beads by Adding Activated Carbon from Coffee Grounds and Crosslinking with Epichlorohydrin.

Carbon dioxide (CO2) capture has been identified as a potential technology for reducing the anthropic emissions of greenhouse gases, particularly in post-combustion processes. The development of adsorbents for carbon capture and storage is expanding at a rapid rate. This article presents a novel sustainable synthesis method for the production of chitosan/activated carbon CO2 adsorbents. Chitosan is a biopolymer that is naturally abundant and contains amino groups (-NH2), which are required for the selective adsorption of CO2. Spent coffee grounds have been considered as a potential feedstock for the synthesis of activated coffee grounds through carbonization and chemical activation. The chitosan/activated coffee ground composite microspheres were created using the emulsion cross-linking method with epichlorohydrin. The effects of the amount of chitosan (15, 20, and 25 g), activated coffee ground (10, 20, 30, and 40%w/w), and epichlorohydrin (2, 3, 4, 5, 6, 7 and 8 g) were examined. The CO2 capture potential of the composite beads is superior to that of the neat biopolymer beads. The CO2 adsorbed of synthesized materials at a standard temperature and pressure is improved by increasing the quantity of activated coffee ground and epichlorohydrin. These findings suggest that the novel composite bead has the potential to be applied in CO2 separation applications.

Agarose-collagen composite microsphere implants: A biocompatible and robust approach for skin tissue regeneration

Photoaged skin, a consequence of UV radiation-induced collagen degradation, presents a significant challenge for skin rejuvenation. Synthetic polymer microspheres, while offering collagen regeneration potential, carry risks like granulomas. To overcome this, we developed a novel agarose-collagen composite microsphere implant for skin tissue regeneration. Fabricated using an emulsification-crosslinking method, these microspheres exhibited excellent uniformity and sphericity (with a diameter of ~38.5 μm), as well as attractive injectability. In vitro studies demonstrated their superior biocompatibility, promoting cell proliferation, adhesion, and migration. Further assessments revealed favorable biosafety and blood compatibility. In vivo experiments in photoaged mice showed that implantation of these microspheres effectively reduced wrinkles, increased skin density, and improved elasticity by stimulating fibroblast encapsulation and collagen regeneration. These findings highlight the potential of agarose-collagen microspheres in dermatological and tissue engineering applications, offering a safer alternative for skin rejuvenation.

Harnessing three-dimensional porous chitosan microsphere embedded with adipose-derived stem cells to promote nerve regeneration

BackgroundNerve guide conduits are a promising strategy for reconstructing peripheral nerve defects. Improving the survival rate of seed cells in nerve conduits is still a challenge and microcarriers are an excellent three-dimensional (3D) culture scaffold. Here, we investigate the effect of the 3D culture of microcarriers on the biological characteristics of adipose mesenchymal stem cells (ADSCs) and to evaluate the efficacy of chitosan nerve conduits filled with microcarriers loaded with ADSCs in repairing nerve defects.MethodsIn vitro, we prepared porous chitosan microspheres by a modified emulsion cross-linking method for loading ADSCs and evaluated the growth status and function of ADSCs. In vivo, ADSCs-loaded microcarriers were injected into chitosan nerve conduits to repair a 12 mm sciatic nerve defect in rats.ResultsCompared to the conventional two-dimensional (2D) culture, the prepared microcarriers were more conducive to the proliferation, migration, and secretion of trophic factors of ADSCs. In addition, gait analysis, neuro-electrophysiology, and histological evaluation of nerves and muscles showed that the ADSC microcarrier-loaded nerve conduits were more effective in improving nerve regeneration.ConclusionsThe ADSCs-loaded chitosan porous microcarrier prepared in this study has a high cell engraftment rate and good potential for peripheral nerve repair.Graphical

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 3 seconds, 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.

Design, Optimization, and Evaluation of Chitosan-2-mercaptobenzoic Acid as a Dual-functionalized Thiomer

Aims: This study aimed to develop and evaluate mucoadhesive microspheres for the controlled release of zidovudine using a novel dual-functionalized polymer. Background: Mucoadhesive polymers have recently been widely used to prolong the GI residence time and to modulate the release impact of various mucoadhesive dosage forms. In the present study, a recently synthesized chitosan derivative, chitosan-2-mercapto benzoic acid, was used as a mucoadhesive polymer, which was further developed as a dosage form for improving oral bioavailability of zidovudine drug. Objective: The objective of this study is to evaluate the impact of a novel thiolated derivative, chitosan-2-mercaptobenzoic acid, on the oral bioavailability of the drug zidovudine. Methods: The microspheres were prepared using an emulsification crosslinking method with TPP as the crosslinking agent. Techniques such as FTIR, and DSC were employed to analyze the microspheres, along with drug content, entrapment efficiency, dissolution studies, mucoadhesion, ex vivo permeation, and in vivo evaluations. Results: Results from FTIR spectroscopy and DSC analysis revealed no interaction between the drug and polymers. The release kinetics and characterization assessments indicated a zero-order release profile with anomalous and super case-II transport types. Ex vivo permeation studies on goat intestinal mucosa demonstrated enhanced mucoadhesive properties and permeability with the optimized microspheres fabricated using thiomers compared to conventional oral therapy. Pharmacokinetic investigations showed higher zidovudine plasma levels and Cmax with the administration of microspheres, particularly those composed of thiomers. The AUC0-24h values for thiomer microspheres were significantly greater than controls and chitosan microspheres, indicating improved oral bioavailability potential. Conclusion: In conclusion, zidovudine-loaded thiomer-based mucoadhesive microspheres showed promising results with the ability to enhance the drug's oral bioavailability.

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.

Preparation of a tetraethylenepentamine grafted magnetic chitosan bead for adsorption of Re(vii) from aqueous solutions.

A cross-linked magnetic chitosan bead (MCB) and tetraethylenepentamine grafted magnetic chitosan bead (TMCB) were synthesized using the water/oil (W/O) emulsion cross-linking method and characterized using scanning electron microscopy (SEM), vibrating-sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The saturation magnetization and remanent magnetization of TMCB were 7.09 emu g-1 and 0.834 emu g-1, respectively, illustrating the superparamagnetic properties of the prepared TMCB. The adsorption properties of MCB and TMCB for the removal of rare metal rhenium from acidic effluents were evaluated. Kinetic experimental data fit well with the pseudo-second-order model, and the adsorption isotherms were better fitted with the Langmuir model. The maximum adsorption capacities of Re(vii) as obtained from the Langmuir model were 224.50 and 257.61 mg g-1 for MCB and TMCB, respectively, at pH 3 and 30 °C. Thermodynamic analysis revealed that the adsorption process is both spontaneous and exothermic. Regeneration experiments were conducted using 2 M NaCl, and TMCB maintained good adsorption and desorption performance after five regeneration cycles, indicating a promising material for the recovery of rhenium from acidic industrial effluents.

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.