Alginate-chitosan Microspheres Research Articles

Homogeneously complexed alginate-chitosan hydrogel microspheres for the viability enhancement of entrapped hepatocytes

The future deployment of biomedicine fields will require a new generation of biodegradable, biocompatible, and non-toxic hydrogels. Alginate and chitosan, naturally occurring polymers, have gained significant interest for hydrogel applications. However, integrating chitosan within alginate-based hydrogels to form microspheres with homogeneous distribution and a tailored surface charge remains challenging. Herein, we report the design and fabrication of homogeneously complexed alginate-chitosan hydrogel microspheres, demonstrating their ability to enhance the viability and liver-specific functionalities of entrapped hepatocytes. By exploring and optimizing the pH and ratio of alginate and chitosan solutions, we achieved well-controlled physicochemical properties, including the degree of sphericity, hydrophilicity, charge property, and surface roughness. Unlike traditional alginate-based hydrogel microspheres, hepatocytes entrapped in homogeneous alginate-chitosan microspheres displayed enhanced viability and liver-specific functions, including albumin secretion, urea synthesis, and cytochrome P-450 enzymatic activity. This work illustrates a potential pathway for manufacturing functionalized microspheres with tunable mechanical properties and functionalities based on biocompatible alginate and chitosan for hepatocyte applications.

Alginate-chitosan-microencapsulated tyrosols/oleuropein-rich olive mill waste extract for lipopolysaccharide-induced skin fibroblast inflammation treatment

The Ca2+ ion-driven emulsification-ionotropic gelation method produced chitosan-alginate microspheres (CAMSs) with a narrow particle size distribution (PSD). Particle size distribution and zeta potential studies, as well as spectral electron microscopy, were used to assess the microspheres' physicochemical properties and morphology. The tyrosols (hydroxytyrosol (HT), tyrosol (TY), and oleuropein (OE) were loaded into these microspheres using a polyphenol extract (PPE) from Koroneki olive mill waste (KOMW). The microencapsulation efficiency and loading capacity of microspheres for PPE were 98.8% and 3.9%, respectively. Three simulated fluids, including gastric (pH = 1.2), intestinal (pH = 6.8), and colonic (pH = 7.4), were used to examine how the pH of the releasing medium affected the ability of CAMSs to release bioactive phenols. At a severely acidic pH (1.2, SGF), PPE release is nearly halted, while at pH 6.8 (SCF), release is at its maximum. Additionally, the PPE-CAMPs have ameliorated the endogenous antioxidant content SOD, GST, GPx with significant values from 0.05 to 0.01 in the treated LPS/human skin fibroblast cells. The anti-inflammatory response was appeared through their attenuations activity for the released cytokines TNF-α, IL6, IL1β, and IL 12 with levels significantly from 0.01 to 0.001. Microencapsulation of PPE by CAMPs significantly improved its antioxidant and anti-inflammatory capabilities.

The recombinant subunit vaccine encapsulated by alginate-chitosan microsphere enhances the immune effect against Micropterus salmoides rhabdovirus.

The disease caused by Micropterus salmoides rhabdovirus (MSRV) has brought substantial economic losses to the largemouth bass aquaculture industry in China. Vaccination was considered as a potential way to prevent and control this disease. As a kind of sustained and controlled release system, alginate and chitosan microspheres (SA-CS) are widely used in the development of oral vaccination for fish. Here, we prepared a king of alginate-chitosan composite microsphere to encapsulate the second segment of MSRV glycoprotein (G2 protein) and then evaluated the immune effect of the microsphere vaccine on largemouth bass. Largemouth bass were vaccinated via intragastric immunization by different treatments (PBS, SA-CS, G2 and SA-CS-G2). The results showed that a stronger immune response including serum antibody levels, immune-related physiological indexes (acid phosphatase, alkaline phosphatase, superoxide dismutase and total antioxidant capacity) and the expression of immune-related gene (IgM、IL-8、IL-1β、CD4、TGF-β、TNF-α) can be induced obviously with SA-CS-G2 groups compared with G2 groups when fish were vaccinated. Furthermore, fish were injected with a lethal dose of MSRV after immunization for 28 days, and the highest relative percentage survival (54.8%) was observed in SA-CS-G2 group (40 μg per fish), which is significantly higher than that of G2 group (25.8%). This study showed that alginate-chitosan microspheres as the vaccine carrier can effectively improve the immune effect of oral vaccination and induce better immune protection effect against MSRV infection.

Preparation and Characterization of Chitosan-Alginate Microspheres Loaded with Quercetin.

The aim of this paper was to formulate microspheres based on biodegradable polymers (chitosan and sodium alginate), using the complex coacervation technique. Subsequently, the prepared microspheres were loaded with quercetin (QUE), a pharmacological active ingredient insoluble in water and unstable to light, temperature and air. After preparation, the loaded microspheres underwent several studies for physical chemical characterization (performed by scanning electron microscopy—SEM, laser 3D scanning, and thermal analysis—TA). Furthermore, they were analyzed in order to obtain information regarding swelling index, drug entrapment, and in vitro release capacity. The obtained experimental data demonstrated 86.07% entrapment of QUE into the microspheres, in the case of the one with the highest Ch concentration. Additionally, it was proved that such systems allow the controlled release of the active drug over 24 h at the intestinal level. SEM micrographs proved that the prepared microspheres have a wrinkled surface, with compact structures and a large number of folds. On the basis of the TA analysis, it was concluded that the obtained microspheres were thermally stable, facilitating their usage at normal physiological temperatures as drug delivery systems.

The design and green nanofabrication of noble hydrogel systems with encapsulation of doped bioactive hydroxyapatite toward sustained drug delivery

Finding a bioactive hybrid material with the potential for a controlled drug release has been one of the major targets of tissue engineering in the recent years. In this line, the present work describes a new approach for producing singular hydrogel microparticles (HMPs) with different morphologies and compositions by combining experimental and computational methods. Calcium-Alginate microparticles (Ca-ALG) and core–shell Alginate-Chitosan microspheres (Ca-ALG-CHI) were synthesized with the presence of drug-doped Hydroxyapatite (HA) in their inner matrix. The methodology relies on the use of a microfluidic system to obtain crosslinked HMPs with homogeneous sizes and morphologies, integrating external and internal gelation. The impact of the water-to-oil volume ratio, as well as variations in the collecting baths, morphology, and dispersion, were considered. The drug models chosen were Propranolol hydrochloride and Cloxacillin sodium salt monohydrate. Avrami's parameters were used to study and address the adsorption kinetics of each drug onto the bioactive HA, and the Korsmeyer-Peppas model was used to analyze the posterior desorption profiles. The conception and development of this type of hydrogel microparticles with improved functionalities are essential for the creation of granular hydrogels, which are an innovative, green, sustained and highly promising solution for different therapies in regenerative medicine areas.

Evaluation of Interleukin-4-Loaded Sodium Alginate-Chitosan Microspheres for Their Support of Microvascularization in Engineered Tissues.

Defects in the formation of microvascular networks, which provide oxygen and nutrients to cells, are the main reason for the engraftment failure of clinically applicable engineered tissues. Inflammatory responses and immunomodulation can promote the vascularization of the engineered tissues. We developed a capillary construct composed of a gelatin methacrylate-based cell-laden hydrogel framework complexed with interleukin-4 (IL-4)-loaded alginate-chitosan (AC) microspheres and endothelial progenitor cells (EPCs) and RAW264.7 macrophages as model cells. The AC microspheres maintained and guided the EPCs through electrostatic adhesion, facilitating the formation of microvascular networks. The IL-4-loaded microspheres promoted the polarization of the macrophages into the M2 type, leading to a reduction in pro-inflammatory factors and enhancement of the vascularization. Hematoxylin and eosin staining and immunohistochemical analysis revealed that, without IL-4 or AC microspheres, the scaffold was less effective in angiogenesis. We provide an alternative and promising approach for constructing vascularized tissues.

Floating chitosan-alginate microspheres loaded with chlorantraniliprole effectively control Chilo suppressalis (Walker) and Sesamia inferens (Walker) in rice fields

Striped rice stem borer, Chilo suppressalis (Walker) and pink stem borer, Sesamia inferens (Walker) are two important pests, causing substantial yield loss in rice production. Application of conventional synthetic pesticides, such as suspension concentrates and water-dispersible granules, is a primary method for control of the two pests. Due to the flow of water in rice field, spray drift, and soil adsorption, applied such pesticides are often out of the target, resulting in low control efficacy, potential contamination of soil or surface water, and also threat to human health. Thus, there is an urgent need for developing environmentally friendly and highly targeted pesticide formulations to meet the challenges. The present study synthesized chlorantraniliprole loaded chitosan-alginate floating hydrogel microspheres (CCAM) through physical embedding, ionic crosslinking, and incorporation of citronellol as an oil phase. The morphology, particle size, entrapment efficiency, loading capacity, in vitro slow-release kinetics, and floating ability of the CCAM were tested in laboratory conditions. The CCAM and two commercial formulations (suspended and granulated) of chlorantraniliprole were respectively evaluated in two rice fields located in two provinces of China. The CCAM was able to float on the surface of rice field, gather around rice stems, and slowly release chlorantraniliprole, which resulted in significantly higher concentrations of chlorantraniliprole in rice stems and leaves for a prolonged time than suspended and granulated controls. The application of CCAM provided an on-target control of both striped stem borer and pink stem borer. Furthermore, CCAM application had very low residue of chlorantraniliprole in soils. As far as is known, this is the first report of chlorantraniliprole loaded on chitosan-alginate floating hydrogel microspheres for rice stem borer control. Our results indicate that the synthesized CCAM could potentially be used as a controlled-release product for effective control of the two rice pests, while reducing the residual chlorantraniliprole in the soil and avoiding pesticide drift.

Development and microbiological evaluation of chitosan and chitosan-alginate microspheres for vaginal administration of metronidazole

Metronidazole is the drug of choice in the treatment of bacterial vaginosis, but the oral therapy can induce several collateral effects. Aim of this work was the development of a vaginal multiparticulate system, loaded with metronidazole, able to improve its residence time allowing a complete drug release. Several kinds of MS were prepared using chitosan dissolved in different organic acids or alginate coated with chitosan. FTIR and DSC analyses were performed to study the interactions between the drug and the polymers, while MS morphology was investigated with optical and electron microscopy. All the formulations were characterized in terms of drug entrapment efficiency, mucoadhesion, swelling capacity and drug release behavior, demonstrating the best results for alginate MS coated with chitosan. The formulations evidenced a complete and rapid release of drug, compared with the commercial form: Zidoval®.The best formulations assayed for antibacterial activity confirmed the suitability of this new formulation for the vaginal treatment of local diseases.

Efficacy of Local Minocycline Agents in Treating Peri-Implantitis: An Experimental In Vivo Study in Beagle Dogs.

Background: Local delivery agents (LDA) have the advantage of delivering the antibiotics at high concentrations to the targeted sites. However, the constant flow of gingival crevicular fluids and saliva may restrict their efficacy. Therefore, the drug sustainability and pharmacodynamic properties of any proposed LDA should be evaluated. Methods: Four dental implants were placed unilaterally in the edentulous mandible of six beagle dogs. Peri-implantitis were experimentally induced using silk-ligatures. Each implant was randomly allocated to receive one of the following four treatments: (i) MC (Chitosan-alginate (CA) minocycline), (ii) MP (CA-without minocycline), (iii) PG (Polyacrylate-glycerin minocycline), and (iv) Control (mechanical debridement only). Mechanical therapies and LDAs were administered into the gingival sulcus two times at a 4-week interval. Drug sustainability as well as clinical, radiographical, and immunohistochemical (IHC) analyses were conducted to evaluate the efficacies of treatments. Results: Reduced mean probing depth was observed in all of the test groups after the second delivery. A minimal marginal bone level change was observed during the treatment period (MP (−0.06 ± 0.53 mm) to PG (−0.25 ± 0.42 mm)). The distribution of IHC cell marker analysis of all targeted antibodies ranged from 6.34% to 11.33%. All treatment outcomes between the test groups were comparable. A prolonged retention of LDA was observed from CA microspheres (MC and MP) at both administrations (p < 0.017) and prolonged sustainability of bacteriostatic effect was observed from MC compared to PG after the second administration (p < 0.05). Conclusions: Prolonged retention of CA microspheres was observed and the longer bacteriostatic effect was observed from the MC group. Mechanical debridement with adjunct LDA therapy may impede peri-implantitis progression, however, prolonged drug action did not lead to improved treatment outcome.

Polymeric Microspheres Containing Human Vocal Fold Fibroblasts for Vocal Fold Regeneration.

Most acellular injectable biomaterials for vocal fold (VF) wound treatment have limited regenerative potential due to their fast enzymatic degradation and limited recruitment of native cells postinjection. The injection of cells as therapeutic treatment often results in apoptosis due to stresses within the needle and the immune response of the host. Degradable microspheres may improve treatment effectiveness by increasing cell residence time, shielding cells during injection, and offering early protection against the immune system response. The objective of the present study was to investigate the potential of human VF fibroblasts encapsulated in polymeric microspheres as an injectable therapeutic treatment in vitro. Alginate, alginate-poly-L-lysine, and alginate-chitosan microspheres were fabricated using electrospraying and characterized in terms of biocompatibility, swelling, and mechanical properties as well as cytokine production. Alginate microspheres were found to have the most desirable properties for VF regeneration. They were resistant to mechanical challenges. They were found to have a stiffness similar to that reported for native VF-lamina propria. They were found to be biocompatible and increased the proliferation of fibroblasts. Human VF fibroblasts encapsulated in alginate microspheres induced the production of interleukin (IL)-8 and IL-4 at 24 hours. The alginate microspheres fabricated in this study were found to offer potential advantages, as cell delivery tool. This study highlights the importance of combining biomaterials and cells to expedite the wound-healing process through cytokine production. Future work is aimed to further analysis of the wound-healing properties the microspheres. NA Laryngoscope, 131:1828-1834, 2021.

Synthesis and evaluation of chitosan-alginate microspheres loaded with various combinations of enrofloxacin and selected phytochemicals against pathogenic bacteria

Synthesis and evaluation of chitosan-alginate microspheres loaded with various combinations of enrofloxacin and selected phytochemicals against pathogenic bacteria

Preparation of pH-Responsive Alginate-Chitosan Microspheres for L-Valine Loading and Their Effects on the A40926 Production.

The glycopeptide A40926 biosynthesized by Nonomuraea gerenzanensis is a precursor of the second generation glycopeptide antibiotic dalbavancin. The skeleton of this glycopeptide consists of seven amino acids and is biosynthesized by the NRPS gene module. L-valine, a branched amino acid, is also a significant precursor for A40926 production. This study details the use of pH-responsive alginate-chitosan microspheres loaded with L-valine prepared by internal emulsification gelation. The effects of process and formulation variables on microsphere size, loading capacity, and encapsulation efficiency were investigated. Then, effects on A40926 production by the pH-responsive microspheres were evaluated in a 10-L fermenter. Results demonstrated that use of the pH-responsive microspheres could improve A40926 yield from 465 to 602mg L-1 in a 10-L scale fermenter.

Controlled release alginate-chitosan microspheres of tolmetin sodium prepared by internal gelation technique and characterized by response surface modeling

Tolmetin sodium (TS) is a powerful non-steroidal mitigating drug for the treatment of rheumatoid joint inflammation, osteoarthritis, and adolescent rheumatoid joint pain. In addition to its gastrointestinal (GIT) problems, TS has a short biological half-life (1 hr). In a trial to overcome these side effects and control the rate of (TS) release, chitosan coated alginate microspheres are recommended. A Box-Behnken experimental design was employed to produce controlled release microspheres of TS in the sodium alginate and chitosan copolymers (Alg-Ch) by emulsification internal gelation methodology. The effect of critical formulation variables namely, drug to polymer ratio (D:P ratio), speed of rotation and span 80% on drug encapsulation efficiency (% EE), drug release at the end of 2 hours (Rel2) and drug release at the end of 8 hours (Rel8) were analyzed using response surface modeling. The parameters were assessed using the F test and mathematical models containing only the significant terms were generated for each parameter using multiple linear regression analysis. The produced microspheres were spherical in shape with extensive pores at D:P ratio 1:1 and small pores at a drug to polymer ratio (D:P ratio) 1:3. Differential scanning calorimetry (DSC) affirmed the steady character of TS in microspheres and revealed their crystalline form. All formulation variables examined exerted a significant influence on the drug release, whereas the speed emerged as a lone factor significantly influencing % EE. Increasing the D: P ratio decreases the release of the drug after two and 8 hours. The increase in speed results in an increase in drug release after two and eight hours. The drug release from the microspheres followed zero order kinetics. TS Alg-Ch microspheres exhibited a significant anti-inflammatory effect on incited rat paw edema after eight hours. These results revealed that the internal gelation technique is a promising method to control TS release and eradicate GIT side effects using Alg-Ch copolymers.

Characterization and microbiological evaluation of chitosan-alginate microspheres for cefixime vaginal administration

Chitosan-alginate microspheres (MS) were developed for cefixime vaginal administration, to overcome problems associated with its oral administration. The effect of increasing drug-loading amount, by keeping the chitosan-alginate content constant, was investigated. Mucoadhesion studies indicated that all formulations assured in situ permanence longer than 2 h. Entrapment efficiency increased with drug loading concentration in the starting solution, reaching a plateau at 30 mg/mL indicative of the achievement of an optimal drug-to-polymer ratio. MS swelling properties increased with the entrapped drug amount, and, interestingly, water-uptake reached its maximum value at the same drug loading concentration of 30 mg/mL. The relationship found between MS water-uptake and drug release rate confirmed MS prepared with 30 mg/mL cefixime as the best formulation. Microbiological studies showed a relation between cefixime release rate from MS and Escherichia coli viability reduction, definitely indicating the selected MS formulation as the best for an effective local treatment of urogenital infections.

Synthesis of chitosan-alginate microspheres with high antimicrobial and antibiofilm activity against multi-drug resistant microbial pathogens

The successful treatment of multi-drug resistant microbial pathogens represents a major challenge for public health management. Here, chitosan-alginate (CS/ALG) microspheres with narrow size distribution were fabricated by ionically cross linking method using Ca2+ ions as agents for polymer solidification. The physicochemical properties of CS/ALG microspheres, such as surface morphology and size, were studied by SEM. The functional group interactions were confirmed by Fourier transform infrared (FTIR) spectroscopy. SEM revealed that the CS/ALG microspheres were spherical in shape with smooth surfaces, size was 50–100 μm. The synthesized CS/ALG microspheres showed antibacterial and antibiofilm activity on bacteria of public health relevance. CS/ALG microspheres exhibited antibacterial activity at the concentration of 5–20 μg, with significant inhibitory zones on multiple antibiotic resistant pathogens, including Gram positive Staphylococcus aureus, Enterococcus faecalis, and Gram negative Pseudomonas aeruginosa and Proteus vulgaris. Furthermore, in situ light microscopy and confocal laser scanning microscopy (CLSM) showed that CS/ALG microspheres inhibited the bacterial biofilm formation in S. aureus, E. faecalis P. aeruginosa and P. vulgaris after a single treatment with 40 μg. Overall, our findings underlined that chemically synthesized CS/ALG biomaterial has high antibacterial and antibiofilm activity against a number of microbial pathogens of interest for human health, thus this synthesis route can be further exploited for drug development in current biomedical science.

FORMULATION AND IN-VITRO-IN-VIVO EVALUATION OF ALGINATE-CHITOSAN MICROSPHERES OF GLIPIZIDE BY IONIC GELATION METHOD

Objective: The present work is aimed to formulate and evaluate alginate-chitosan microspheres of glipizide for the effective use in the treatment of diabetes.Methods: Sustained release microspheres were prepared by gentle mixing of polymers in water phase with drug by agitation. The polymers used for preparation were sodium alginate and chitosan, which was extruded into 5% calcium chloride solution to produce microspheres by ionic gelation method.Results: Single unit dosage form of Glipizide causes gastric irritation. To convert it in to the multiple unit dosage form will release the drug evenly throughout the stomach which suppresses the irritation. The aim of study towards formulation and evaluation of alginate-chitosan microspheres, which can provide sustained release of the model drug. It shows better in-vitro and in-vivo activity than conventional dosage forms. The work also aims to study various parameters affecting the behavior of microspheres in oral dosage form. Conclusion: Drugs that are simply absorbed from the gastrointestinal tract (GIT) and having a short half life are eliminated rapidly from the blood flow. To avoid this trouble, the oral sustained release (SR) has been developed as these will release the drug slowly in to the GIT and maintain a stable drug concentration in the serum for a longer period of time.

Effects of ginsenoside Rg1-loaded alginate-chitosan microspheres on human bone marrow stromal cells.

The ginsenoside Rg1 is the most abundant compound in ginseng. Recent studies showed that Rg1 had neuroprotective effects on neuronal cells. The present study was to prepare Rg1-loaded alginate-chitosan microspheres and research the effects of microspheres on human bone marrow (BM) stromal cells (hBMSC). The alginate-chitosan microspheres were prepared by mechanical emulsification technique in combination with ion (Ca2+) and chitosan solidification. Subsequently, the microspheres were employed to load Rg1 ginseng extracts. The microspheres had a smooth surface and were spherical in shape. The average diameter of the microspheres was 3.95 µm. The loading efficiency was approximately 2.12%. The purity of isolated hBMSC was over 98.8%. Rg1-loaded microspheres could promote hBMSC proliferation and differentiation. Meanwhile, Rg1-loaded microspheres could also suppress hBMSC apoptosis induced by hypoxia-reoxygenation. In conclusion, these loaded microspheres may be used in the research of neuroprotective effects of Rg1.

FORMULATION AND EVALUATION OF SUSTAINED RELEASE MICROSPHERES OF ATORVASTATIN USING CHITOSAN AND ALGINATE

Certain problems regarding the drugs like high first pass metabolism, also the bioavailability of the certain drugs varies due to instability in acidic environment of stomach. Hence, to resolve such problems the drug should be incorporated in the microspheres for sustained release using a suitable polymer. Natural polymer like chitosan gained great interest in pharmaceutical sector because of its advantages like biodegradability, biocompatibility, non-toxicity, non-immunogenicity and low cost. In the present study, formulation and evaluation of polymeric microspheres of Atorvastatin Calcium was carried out and the release profile of such drug using the alginate and chitosan was studied. Microspheres were prepared for sustained release of drug using chitosan and alginate polymers by ionotropic gelation method. Microspheres were spherical in shape, having good flow properties and further its encapsulation efficiency, swelling index, micromeritic study, in- vitro drug release study and stability studies were performed in order to characterize microspheres. Three different concentrations of sodium alginate (1%, 2% and 3%) were used. The higher encapsulation efficiency was observed as the concentration of alginate increased. This is due to the greater availability of active calcium binding sites in the polymeric chains and consequently the greater degree of cross linking. The highest encapsulation efficiency (88.36) was achieved with 2% w/v sodium alginate in combination with 3% chitosan (F6). Among the prepared formulations with respect to the entrapment efficiency, swelling studies and in vitro drug release, the alginate-chitosan microspheres prepared by ionotropic gelation using calcium chloride found to be better than ionically cross linked alginate spheres alone. Therefore, dual cross-linked, microspheres are promising carrier for sustained release of drug.

Omp16-based vaccine encapsulated by alginate-chitosan microspheres provides significant protection against Haemophilus parasuis in mice

Haemophilus parasuis (H. parasuis) is the etiological agent of swine Glässer’s disease, which leads to significant economic loss in swine industry over the world. Subunit vaccine based on outer membrane protein is one of the promising choices to protect pigs against H. parasuis infection despite low immunity efficiency. In this paper, outer membrane protein 16 (Omp16) of H. parasuis encapsulated by alginate-chitosan microspheres as antigen carriers was explored for the first time in a mouse model. Our results showed that the microspheres with Omp16 induced significant higher H. parasuis-specific antibodies, and higher titers of IL-2, IL-4, and IFN-γ than those by Omp16-FIA in treated mice (p<0.05). Moreover, H. parasuis load in the tissues from liver, spleen, and lung of mice immunized with microspheres containing Omp16 was significantly decreased (p<0.05) than that in the same counterpart tissues of control groups. In addition, 80% mice treated with Omp16 and 70% mice with Omp16-FIA were survived after challenged with H. parasuis virulent strain LY02 (serovar 5). Therefore, Omp16-based microsphere vaccine induces both humoral and cellular immune responses and provides promising protection against H. parasuis infection in mice.

Colon targeted oral drug delivery system based on alginate-chitosan microspheres loaded with icariin in the treatment of ulcerative colitis

In recent years, oral colon specific drug delivery system has been paid more attention in the treatment of inflammatory bowel disease (IBD). As the special pH condition in gastrointestinal tract, the challenge for treatment of IBD was that the colon drug delivery system should endure the low pH in stomach and release drugs quickly in high pH in colon. Icariin with the poor solubility and low bioavailability limited the treatment of many diseases in clinic. In this study, the protective mechanism of alginate-chitosan microspheres loaded with icariin were investigated with trinitrobenzene sulfonic acid (TNBS)/ethanol induced colonic mucosal injury in rats. The results of drug release showed that the icariin loaded into microspheres released only 10% in simulated gastric fluid and a high amount of 65.6% released in simulated colonic fluid. The fluorescence tracer indicated high retention of targeted microspheres more than 12h in colon. The microspheres loaded with icariin could not only reduce the colonic injury by decreasing the colon mucosa damage index in rats, but also reduce the inflammatory response by reducing the production and gene expression of inflammatory mediators and cytokines in colonic mucosa. All the results indicate that targeted microspheres loaded with icariin could exert the colon-protective effects through reducing the inflammatory response, which would be developed as a potential drug controlled release system for treatment of ulcerative colitis.