Co-reporter:Ruyun Lou, Weiting Yu, Yizhe Song, Ying Ren, Huizhen Zheng, Xin Guo, Yunfei Lin, Guoyu Pan, Xiuli Wang, Xiaojun Ma
Carbohydrate Polymers 2017 Volume 155() pp:456-465
Publication Date(Web):2 January 2017
DOI:10.1016/j.carbpol.2016.08.098
L-NH2-OH-alginate based microcapsules were designed for hepatocyte applications.L-NH2-OH-alginate was fabricated via grafting LA onto hydroxyl groups of alginate.The prepared microcapsules demonstrated an excellent stability.The functional of primary hepatocytes in the prepared microcapsules was improved.Galactose moieties are covalently coupled with sodium alginate to enhance liver-specific functions in microcapsules owing to the specific interaction between the galactose moieties and the asialoglycoprotein receptors (ASGPRs) of hepatocytes. In this study, galactosylated alginate (L-NH2-OH-alginate) based microcapsules with desirable stability and a suitable 3D microenvironment are designed and fabricated for primary hepatocyte applications. The designed L-NH2-OH-alginate is fabricated via the application of ethylenediamine grafted lactobionic acid (L-NH2) onto the hydroxyl groups of sodium alginate so that the negatively charged carboxyl groups intact in L-NH2-OH-alginate can effectively bond with Ca2+ to form a stable three-dimensional gel network; a subsequent reaction with polycations forms a stable membrane of microcapsules. As a result, L-NH2-OH-alginate based microcapsules exhibit an excellent mechanical stability. Moreover, with a higher degree of substitution in L-NH2-OH-alginate (DS 0.41), the hepatocytes entrapped in L-NH2-OH-alginate microcapsules exhibit better viability and well-maintained liver-specific functions.
Co-reporter:Huizhen Zheng, Meng Gao, Ying Ren, Ruyun Lou, Hongguo Xie, Weiting Yu, Xiudong Liu, Xiaojun Ma
Carbohydrate Polymers 2017 Volume 155() pp:329-335
Publication Date(Web):2 January 2017
DOI:10.1016/j.carbpol.2016.08.096
•A pH-responsive gel based on EDTA-Ca-Alg was achieved by in-situ release of Ca2+.•The polysaccharide gel exhibited pH-dependent mechanical behaviors.•pH-Responsive gel microspheres were formed for oral delivery of probiotics.A pH-responsive carrier based on an ethylenediaminetetraacetic-calcium-alginate (EDTA-Ca-Alg) system was developed by controlling the release of Ca2+. The system remained in the solution state at neutral pH since EDTA completely chelated the Ca2+. In contrast, a hydrogel immediately formed when the pH was below 4.0, which triggered the in situ release of Ca2+ from the EDTA-Ca compound and led to alginate-Ca binding. Taking advantage of the pH sensitivity, we prepared hydrogel microspheres with uniform size to entrap Lactobacillus rhamnosus ATCC 53103 through emulsification. In an acidic environment, the hydrogel structure remained compact with negligible pores to protect L. rhamnosus ATCC 53103. However, in a neutral intestinal environment, the hydrogel structure gradually disassembled because of the Ca2+ release from the hydrogel, which caused cell release. Therefore, a pH-responsive carrier was developed for the protection and the controlled release of cells in gastrointestinal tract, thus providing potential for oral delivery of probiotics.
Co-reporter:Ying Ren, Ruyun Lou, Xiaocen Liu, Meng Gao, Huizhen Zheng, Ting Yang, Hongguo Xie, Weiting Yu and Xiaojun Ma
Chemical Communications 2016 vol. 52(Issue 37) pp:6273-6276
Publication Date(Web):05 Apr 2016
DOI:10.1039/C6CC02472F
We report a strategy to synthesize self-healing hydrogels via exploiting endothermic interactions between polyelectrolytes. Natural polysaccharides and their derivatives were used to form reversible polyelectrolyte complexes by selecting appropriately charged chemical groups and counterions. This simple and effective method to fabricate self-healing hydrogels will find applications in diverse fields such as surface coating and 3D printing.
Co-reporter:Huizhen Zheng, Meng Gao, Ying Ren, Ruyun Lou, Hongguo Xie, Weiting Yu, Xiudong Liu, and Xiaojun Ma
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 30) pp:19333
Publication Date(Web):July 12, 2016
DOI:10.1021/acsami.6b05778
The surface properties of implanted materials or devices play critical roles in modulating cell behavior. However, the surface properties usually affect cell behaviors synergetically so that it is still difficult to separately investigate the influence of a single property on cell behavior in practical applications. In this study, alginate–chitosan (AC) microcapsules with a dense or loose gel structure were fabricated to understand the effect of gel structure on cell behavior. Cells preferentially adhered and spread on the loose gel structure microcapsules rather than on the dense ones. The two types of microcapsules exhibited nearly identical surface positive charges, roughness, stiffness, and hydrophilicity; thus, the result suggested that the gel structure was the principal factor affecting cell behavior. X-ray photoelectron spectroscopy analyses demonstrated that the overall percentage of positively charged amino groups was similar on both microcapsules. The different gel structures led to different states and distributions of the positively charged amino groups of chitosan, so we conclude that the loose gel structure facilitated greater cell adhesion and spreading mainly because more protonated amino groups remained unbound and exposed on the surface of these microcapsules.Keywords: alginate−chitosan microcapsule; cell adhesion and spreading; gel structure; protonated amino; surface property
Co-reporter:Yizhe Song, Demeng Zhang, Yan Lv, Xin Guo, Ruyun Lou, Shujun Wang, Xiuli Wang, Weiting Yu, Xiaojun Ma
Carbohydrate Polymers 2016 Volume 153() pp:652-662
Publication Date(Web):20 November 2016
DOI:10.1016/j.carbpol.2016.07.058
•A collagen/alginate-chitosan (Col/Alg-Chi) hydrogel membrane-based co-culture system was developed with an aim to explore the effect of intercellular distance between hepatocytes and stromal cells on the functionality of hepatocytes. Intercellular distance of the two types of cells was controlled by the membrane thickness of the Col/Alg-Chi membrane, which was adjusted by reaction time and concentration of chitosan.•Intercellular distance between the hepatocytes and the fibroblasts exerted significant influence on the hepatic function in vitro. Maintenance of the functionality of primary hepatocytes requires direct contact between hepatocytes and their supportive stromal cells, and their effective contact distance is within 30 μm.•The Col/Alg-Chi membrane-based system is highly advantageous for studying the effect of intercellular distance on cell-cell interactions and provides a robust tool to explore the impact of both cell-cell contact and paracrine signaling in the co-cultures in vitro.Indirect cell contact co-culture system is increasingly becoming more attractable owing to their advantages of easy cell separation and desirable outcomes for cell–cell interactions. However, how to precisely control the spatial position of cells within multicellular co-cultures is still experimentally challenging due to the incapability of the conventional methods in vitro. In the present study, a tunable collagen/alginate-chitosan (Col/Alg-Chi) membrane was established, which was capable of controlling intercellular distance between the neighboring cells at a level of micrometer resolution. It was showed that intercellular distance between the hepatocytes and the fibroblasts exerted significant influence on hepatic function in vitro. In particular, maintenance of the functionality of primary hepatocytes requires direct contact between the hepatocytes and their supportive stromal cells, and their effective contact distance is within 30 μm. This technical platform would potentially enable investigations of dynamic cell–cell interaction in a multitude of applications including organogenesis, development or even neoplastic transformation.
Co-reporter:Meng Gao, Huiyi Song, Huizhen Zheng, Ying Ren, Shen Li, Xiudong Liu, Weiting Yu, Xiaojun Ma
Carbohydrate Polymers 2016 Volume 141() pp:160-165
Publication Date(Web):5 May 2016
DOI:10.1016/j.carbpol.2016.01.011
•Cells in ELDCwc group have superior stress resistant ability to dEHDC group.•Stress resistance of encapsulated bacteria was explained in quorum sensing aspect.•The luxS deficient E. coli strain possessed weaker stress resistance in microcapsules.Entrapped low density cells with culture (ELDCwc) have been proved as a more effective way than direct entrapped high density cells (dEHDC) and free cells to protect probiotics from harsh environment, that is, to improve their stress resistance. The aim of this study was to investigate whether bacterial quorum sensing (QS) facilitated the stress resistance of Escherichia coli in microcapsules by detecting the expression of luxS/AI-2 system. As a result, both the expression of luxS gene and the concentration of autoinducer-2 (AI-2, QS signal molecule) have been discovered higher in ELDCwc than in dEHDC and free cells. Besides that, the luxS mutant E. coli strain was used as a negative control of QS to verify the influence of QS on bacterial stress resistance in microcapsules. The significantly decreased viability of luxS mutant strain in simulated gastric fluid also indicated that the QS played a critical role in protecting microorganisms from severe environment.
Co-reporter:Guoshuang Zheng;Huizhen Zheng;Hongguo Xie;Xiudong Liu;Xiaojun Ma
Journal of Biomedical Materials Research Part A 2016 Volume 104( Issue 1) pp:257-263
Publication Date(Web):
DOI:10.1002/jbm.a.35562
Abstract
Alginate-chitosan (AC) microcapsules with desired strength and biocompatibility are preferred in cell-based therapy. Sequential assembly of higher and lower deacetylated chitosans (C1 and C2) on alginate has produced AC1C2 microcapsule with improved membrane strength and biocompatibility. In this article, the assembly and complexation processes of two cationic chitosans on anionic alginate were concerned, and the cause and influence of sequentially assembling chitosans on AC1C2 microcapsules membrane formation were evaluated. It was found that C1 complexation was the key factor for deciding the membrane thickness of AC1C2 microcapsule. Specifically, the binding amount of C2 positively related to the binding amount of C1, which suggested the first layer by C1 complexation on alginate had no obvious resistance on the sequential cationic C2 complexation. Further analyses demonstrated that outward migration of alginate molecules and inward diffusion of both chitosans under electrostatic interaction contributed to the sequential coating of C2 on first C1 layer. Moreover, C2 complexation through the surface to inner layer of membrane helped smoothen the first layer by C1 complexation that displayed a synergy role on the formation of AC1C2 microcapsule membrane. Therefore, the two chitosans played different roles and synergistically contributed to membrane properties that can be easily regulated with membrane complexation time. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 257–263, 2016.
Co-reporter:Yizhe Song;Guoshuang Zheng;Demeng Zhang;Yan Lv;Na Li;Xiuli Wang;Xiaojun Ma
Journal of Applied Polymer Science 2016 Volume 133( Issue 12) pp:
Publication Date(Web):
DOI:10.1002/app.43100
ABSTRACT
In this study, an improved indirect cell coculture system was constructed by using a polyelectrolyte complex membrane generated by alginate (A) and chitosan (C). Methodologies of characterizing thickness and permeability of flat AC membrane were first established due to the importance of these two parameters in determining intercellular distance and degree of contact between cocultured cells. Compared to reaction time, both alginate concentration and molecular weight (Mw) of chitosan play more dominant roles in determining the membrane thickness and diffusion coefficients. Moreover, cells in the alginate gel and on the AC membrane could maintain high cell viability. Thus, an improved indirect cell coculture system constructed by flat AC membrane was fabricated and characterized, which provides a robust tool to study the effect of intercellular distance and degree of contact between cocultured cells on cell–cell interactions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43100.
Co-reporter:Huizhen Zheng, Hongguo Xie, Hao Wu, Feng Wang, Xiudong Liu, Weiting Yu, Xiaojun Ma
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 484() pp:457-462
Publication Date(Web):5 November 2015
DOI:10.1016/j.colsurfa.2015.08.028
•Surface morphology of calcium alginate hydrogel microspheres was characterized at original wet state by a noncontact optical interferometer.•Surface roughness of microspheres in situ was significantly smaller than that of flat membrane.•After chitosan reaction, surface roughness of microcapsules kept the same level as microspheres.•Fractal dimension of microspheres was obviously lower in wet than that in drying and moist state.Surface morphology of calcium alginate hydrogel microspheres (CAHM) with ultrahigh water content has been found to affect the interaction with proteins and cells in vivo. In this study, an optical interferometer is developed to firstly characterize spherical surface morphology of CAHM in wet and in situ under normal pressure and temperature. CAHM shows smoother surface with significant lower roughness than flat alginate membrane, which also contribute to significantly different surface morphology between spherical microcapsules and flat membrane after coating with chitosan. These results help to update the previous knowledge that flat surface can be used to simulate spherical surface for understanding hydrogel behavior to protein adsorption. Meanwhile, CAHM is characterized by SEM techniques with drying process at varying degrees, which demonstrates deviated surface morphology to the original wet surface. Therefore, the optical interferometer is proved a useful tool to acquire the authentic and accurate surface information of spherical hydrogels at applied wet state.
Co-reporter:Guoshuang Zheng;Xiudong Liu;Xiuli Wang;Li Chen;Hongguo Xie;Feng Wang;Huizhen Zheng;Xiaojun Ma
Macromolecular Bioscience 2014 Volume 14( Issue 5) pp:655-666
Publication Date(Web):
DOI:10.1002/mabi.201300474
Cell encapsulation technology holds promise for the cell-based therapy. But poor mechanical strength and biocompatibility of microcapsule membrane are still obstacles for the clinical applications. A novel strategy is presented to prepare AC1C2A microcapsules with bi-functional membrane (that is, both desirable biocompatibility and membrane stability) by sequentially complexing chitosans with higher deacetylation degree (C1) and lower deacetylation degree (C2) on alginate (A) gel beads. Both in vitro and in vivo evaluation of AC1C2A microcapsules demonstrate higher membrane stability and less cell adhesion, because the introduction of C2 increases membrane strength and decreases surface roughness. Moreover, diffusion test of AC1C2A microcapsules displays no inward permeation of IgG protein suggesting good immunoisolation function. The results demonstrate that AC1C2A microcapsules with bi-functional membrane could be a promising candidate for microencapsulated cell implantation with cost effective usage of naturally biocompatible polysaccharides.
Co-reporter:Huiyi Song, Weiting Yu, Xiudong Liu, Xiaojun Ma
Carbohydrate Polymers 2014 Volume 108() pp:10-16
Publication Date(Web):8 August 2014
DOI:10.1016/j.carbpol.2014.02.084
•Microencapsulated probiotics had higher viability in stress environments.•Microencapsulated low density cells with culture were established as new technique.•Cell culture improved stress resistance of microencapsulated low density cells.In this study, probiotics (Saccharomyces cerevisiae Y235) were entrapped in alginate–chitosan microcapsules by emulsification/internal gelation technique. Two different encapsulation patterns were established as directly entrapped high density cells (dEHDC) and entrapped low density cells with culture (ELDCwc). The performance of microencapsulated cells, with free cells (FC) as control, was investigated against sequential stress environments of freeze-drying, storage, and simulated gastrointestinal fluids. After being freeze-dried without cryoprotectant, the survival rate of ELDCwc (14.33%) was significantly higher than 10.00% of dEHDC, and 0.05% of FC. The lower temperature (−20 °C) and ELDCwc pattern were beneficial for keeping viable cells at 7.00 log CFU g−1 after 6 months. Furthermore, the ELDCwc microcapsule maintained viable cells of 6.29 log CFU g−1 after incubation in SGF and SIF. These studies demonstrated that the pattern of entrapped low density cells with culture was an effective and superior technique of resisting harmful stress environments.
Co-reporter:Huiyi Song, Weiting Yu, Meng Gao, Xiudong Liu, Xiaojun Ma
Carbohydrate Polymers 2013 Volume 96(Issue 1) pp:181-189
Publication Date(Web):1 July 2013
DOI:10.1016/j.carbpol.2013.03.068
•Two emulsification gelation techniques showed significant property differences.•Microencapsulated probiotics by emulsification/internal gelation had higher viability.•Higher stress resistance ability in microencapsulated cell culture process.Alginate–chitosan microcapsules containing probiotics (Yeast, Y235) were prepared by emulsification/external gelation and emulsification/internal gelation techniques respectively. The gel beads by external gelation showed asymmetrical structure, but those by internal gelation showed symmetrical structure in morphology. The cell viability was approximately 80% for these two techniques. However, during cell culture process, emulsification/internal gelation microcapsules showed higher cell growth and lower cell leakage. Moreover, the survival rate of entrapped low density cells with culture (ELDCwc) increased obviously than that directly entrapped high density cells (dEHDC) and free cells when keeping in simulated gastrointestinal conditions. It indicated the growth process of cells in microcapsule was important and beneficial to keep enough active probiotics under harmful environment stress. Therefore, the emulsification/internal gelation technique was the preferred method for application in food or biotechnological industries.
Co-reporter:Ying Ren, Hongguo Xie, Xiaocen Liu, Jie Bao, Weiting Yu, Xiaojun Ma
International Journal of Biological Macromolecules (March 2016) Volume 84() pp:135-141
Publication Date(Web):1 March 2016
DOI:10.1016/j.ijbiomac.2015.12.008
The binding properties of poly-l-lysine and chitosan to alginate have been evaluated quantitatively and compared. Poly-l-lysine bound to alginate hydrogel more rapidly than chitosan as poly-l-lysine has a smaller molar hydrodynamic volume. In addition, poly-l-lysine showed a much higher binding capacity (6.14:1) for alginate hydrogel beads than chitosan (2.71:1), and a little higher binding stoichiometry (0.58) to sodium alginate molecules in solution than chitosan (0.49). An exothermic heat of alginate-poly-l-lysine complexes formation of 2.02 kJ/mol was detected. For alginate–chitosan complexes, the binding enthalpy has been seen to be −3.49 kJ/mol. The stability of the polyelectrolyte complexes was related to their binding enthalpy. The alginate-poly-l-lysine complexes could be disintegrated and rebuilt. By contrast, chitosan was bound with alginate in a steady state. These results provide fundamental insights regarding the structure and property relationships of macromolecules, and will be helpful in designing and selecting appropriate polymers.
Co-reporter:Demeng Zhang, Yizhe Song, Yu Wang, Xiudong Liu, ... Xiaojun Ma
Journal of Pharmaceutical Sciences (January 2016) Volume 105(Issue 1) pp:301-307
Publication Date(Web):1 January 2016
DOI:10.1002/jps.24698
Small-interfering RNA (siRNA)-mediated gene silencing with the aid of chitosan (CS)-based carriers has shown efficient and reliable outcome in vitro, but the gene silencing efficiency in vivo is still limited. It is of great importance to balance the protection and release of siRNA from nanoparticles (NPs) so as to achieve high efficiency. However, siRNA release profile from CS/siRNA NPs has been rarely concerned. Here, Förster resonance energy transfer technique was adopted for in vitro investigation of siRNA release from CS NPs in lysozyme-contained buffer. The results clearly showed that siRNA molecules experienced a fast and short release phase under lysozyme competition to both CS and siRNA, and then a slow and long release under lysozyme degradation on CS. Moreover, lysozyme competition played more important role than enzymolysis on trigging siRNA release. This preliminary study of siRNA release is the first step to get insight of in vivo siRNA release mechanism from CS/siRNA NPs, which will be helpful to adjust the design of CS/siRNA NPs for balancing the protection and release of siRNA molecules.
Co-reporter:Meng Gao, Huiyi Song, Xiudong Liu, Weiting Yu, Xiaojun Ma
Journal of Bioscience and Bioengineering (April 2016) Volume 121(Issue 4) pp:406-412
Publication Date(Web):1 April 2016
DOI:10.1016/j.jbiosc.2015.08.010
•Quorum sensing of microencapsulated Vibrio harveyi has been demonstrated.•ELDCwc method promotes cells to grow into aggregation structure.•Improved quorum sensing capacity has been proved with encapsulated cell aggregates.Microcapsule entrapped low density cells with culture (ELDCwc), different from free cell culture, conferred stronger stress resistance and improved cell viability of microorganisms. In this paper, the quorum sensing (QS) system of Vibrio harveyi was used to investigate changes when cells were cultured in microcapsules. Cells in ELDCwc group grew into cell aggregates, which facilitated cell–cell communication and led to increased bioluminescence intensity. Moreover, the luxS-AI-2 system, a well-studied QS signal pathway, was detected as both luxS gene and the AI-2 signaling molecule, and the results were analyzed with respect to QS capacity of unit cell. The V. harveyi of ELDCwc also showed higher relative gene expression and stronger quorum sensing capacity when compared with free cells. In conclusion, the confined microcapsule space can promote the cell aggregates formation, reduce cell–cell communication distance and increase local concentration of signal molecule, which are beneficial to bacterial QS.
Co-reporter:Ying Ren, Ruyun Lou, Xiaocen Liu, Meng Gao, Huizhen Zheng, Ting Yang, Hongguo Xie, Weiting Yu and Xiaojun Ma
Chemical Communications 2016 - vol. 52(Issue 37) pp:NaN6276-6276
Publication Date(Web):2016/04/05
DOI:10.1039/C6CC02472F
We report a strategy to synthesize self-healing hydrogels via exploiting endothermic interactions between polyelectrolytes. Natural polysaccharides and their derivatives were used to form reversible polyelectrolyte complexes by selecting appropriately charged chemical groups and counterions. This simple and effective method to fabricate self-healing hydrogels will find applications in diverse fields such as surface coating and 3D printing.
