Biomedical subjects

Jian Ji

Publications and source records attributed to Jian Ji.

At least 19 recordsLinked to original sources

PubMed2006

Construction of antibacterial multilayer films containing nanosilver via layer-by-layer assembly of heparin and chitosan-silver ions complex.

Antibacterial multilayer films containing nanosilver were prepared via layer-by-layer fashion. PET film was aminolyzed with 1,6-hexanediamine to introduce amino groups on PET film surface; chitosan-silver nitrate complex and heparin were alternately deposited onto an aminolyzed PET film surface, and subsequently, the silver ions within the multilayer films were reduced with ascorbic acid to form silver nanoparticles. UV-visible spectroscopy and transmission electron microscopy confirmed the formation of well-dispersed nanosilver particles with sizes (10-40 nm) that depended on the initial concentration of silver ions in chitosan solution and the pH of ascorbic acid solution. The chitosan/heparin multilayer films were possessed of bactericidal effect on Escherichia coli (E. coli), and this antibacterial effect could be significantly enhanced by the incorporation of silver nanoparticles into the multilayer films. The multilayer films containing nanosilver were not only effective as antibacterial but also as anticoagulant coating. And cell toxicity evaluation suggested that the multilayer films containing nanosilver did not show any cytotoxicity. The multilayer films containing nanosilver may have good potentials for surface modification of medical devices, especially for cardiovascular implants.

Animals↗

PubMed2006

Adventitial fibroblasts are activated in the early stages of atherosclerosis in the apolipoprotein E knockout mouse.

The role of the adventitia in vascular function and vascular lesion formation has been largely ignored. This study observed the activation of the adventitia and specifically the fibroblasts in the development of atherosclerosis in the apoE(-/-) mouse. The results showed a gradual increase in expression of collagen types I and III after 2, 4, and 8 weeks of hyperlipidic diet. The earliest expression of monocyte chemoattractant protein-1 (MCP-1) protein and mRNA was detected in the adventitial fibroblast before the formation of intimal lesions. Proliferation, too, was first found in the adventitial fibroblasts. We hypothesize that the adventitial fibroblast is activated in the early stage of atherosclerosis. Adventitial inflammation may be an early event in the development of atherosclerotic lesions.

Animals↗

PubMed2006

[Comparative study of eukaryotic cell expression of wild-type and Pro370Leu mutation type myocilin gene].

OBJECTIVE: To compare the eukaryotic cell expression of wild-type myocilin (MYOC) (wMYOC) gene and Pro370Leu mutation type MYOC (mMYOC) gene so as to understand the mechanism of primary open angle glaucoma (POAG). METHODS: HeLa cells were cultured and then transfected with the vector pEGFP-N3-wMYOC, recombinant plasmid with wild type MYOC gene and enhanced green fluorescein gene, or the vector pDsRed2-N1-mMYOC, recombinant plasmid with mutation MYOC gene and red fluorescein gene, respectively, or co-transfected with these 2 plasmids. Corresponding blank vectors pEGFP-N3 and pDsRed2-N1 were used as markers. Fluorescence microscopy was used to observe the localization of red fluorescence and green fluorescence. Laser co-focusing microscopy was used to observe the effect of co-transfection. The green and red fluorescein antibodies were examined by Western blotting. RESULTS: Green fluorescence was observed in the cytoplasm of the HeLa cells transfected with the blank vector pEGFP-N3, in an even distribution; and red fluorescence was observed in the cytoplasm of the HeLa cells transfected with the blank vector pDsRed2-N1, in an even distribution too. The cells transfected with pEGFP-N3-wMYOC showed evenly-distributed green fluorescence in the cytoplasm, and the cells transfected with pDsRed2-N1-mMYOC showed red fluorescence in the cytoplasm in a state of aggregation. Both red and green fluorescence could be seen in the cells co-transfected with pEGFP-N3-wMYOC and pDsRed2-N1-mMYOC, both in a state of aggregation and co-localization. Laser co-focusing microscopy showed the same results. Protein with the relative molecular weight of 83,000, identical to that of the recombinant protein of wMYOC protein and green fluorescein, could be found in the culture fluid and cell lysate of the pEGFP-N3-wMYOC-transfected cells; however, could be found in the lysate only but not in the culture fluid of the co-transfected cells. Protein with the relative molecular weight of 81,000, identical to that of the recombinant protein of mMYOC protein and red fluorescein, could be found in the cell lysates of the pDsRed2-N1-mMYOC-transfected cells and the pEGFP-N3-wMYOC and pDsRed2-N1-mMYOC co-transfected cells, but not in the culture fluid of both cells. CONCLUSION: Both the WMYOC and mMYOC genes can be expressed and localized in the cytoplasm. mMYOC protein shoes a tendency of aggregation and disorder in secretion, and affects the expression and secretion of wMYOC, thus influencing the factions of the trabecular meshwork and causing POAG.

Blotting, Western↗

PubMed2006

Poly(D,L-lactic acid)-block-(ligand-tethered poly(ethylene glycol)) copolymers as surface additives for promoting chondrocyte attachment and growth.

The poly(D,L-lactic acid)-block-(ligand-tethered poly(ethylene glycol)) copolymer was explored to engineer poly(D,L-lactic acid) (PLA) material to promote chondrocyte attachment and growth. The poly(D,L-lactic acid)-block-poly(ethylene glycol) copolymer (PLE) was synthesized by a coupling reaction between PLA and poly(ethylene glycol) (PEG) (M(n) 1000, 2000, and 4000 respectively), with the use of 4,4'-methylenediphenyl diisocyanate (MDI). Then the PLE was activated by methyl sulfonyl chloride and the amino acids or arginine-glycine-aspartic acid tripeptide (RGD) was attached, which was verified by the ninhydrin-UV method. The modified PLA films were simply prepared by blending PLA with PLE derivatives. ATR-FTIR, XPS, contact angle, and AFM results clearly showed that the PEG chain stably enriched on the surface of PLE-modified PLA films. The chondrocyte cytocompatibility test showed the modified PLA films could significantly improve chondrocyte attachment and proliferation.

Cell Adhesion↗

PubMed2006

Synthesis and characterization of cholesterol-poly(ethylene glycol)-poly(D,L-lactic acid) copolymers for promoting osteoblast attachment and proliferation.

A novel cholesterol-poly(ethylene glycol)-poly(D,L-lactic acid) copolymer (CPEG-PLA) has been synthesized as a potential surface additive for promoting osteoblast attachment and proliferation. The gel permeation chromatography (GPC) and nuclear magnetic resonance spectroscopy (NMR) results indicated the product had expected structure with low polydispersities in the range of 1.1-1.5. By blending the poly(D,L-lactic acid) (PLA) with CPEG-PLA, the surface of modified PLA membrane was investigated by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle. The results revealed the enrichment of PEG chain on the surface. Osteoblast cell line (MC3T3) was chosen to test the cell behavior on modified PLA membranes. The osteoblast test about cell attachment, proliferation, cell viability and cell morphology investigation on CPEG-PLA modified PLA substrates showed the CPEG-PLA with 15 and 5 ethylene glycol units promoted osteoblast attachment and growth, while the CPEG-PLA with 30 ethylene glycol units prevent osteoblast adhesion and proliferation. This simple surface treatment method may have potentials for tissue engineering and other biomedical applications.

3T3 Cells↗

PubMed2005

Construction and deconstruction of PLL/DNA multilayered films for DNA delivery: effect of ionic strength.

Through the layer-by-layer (LbL) self-assembly technique, DNA was incorporated into the multilayered films with poly-l-lysine (PLL). The effect of ionic strength on the construction and deconstruction of the PLL/DNA films was investigated. It was found that the salt concentration of the deposition solution had a significant effect on the construction of the films, which might attribute to the effect of salt ions on the conformation of polyelectrolytes and interaction between PLL and DNA molecules. A salt-induced deconstruction of the PLL/DNA films was observed. The extent of the deconstruction increased with the salt concentration in the incubation solution. The mechanism of the deconstruction was discussed. Taking the advantages of the LbL technique, the erasable PLL/DNA films could deposit onto a variety of surfaces, such as vascular stent, intervention catheter and tissue engineering scaffold, to serve as a novel DNA delivery system.

Biocompatible Materials↗

PubMed2005

Novel biomimetic polymersomes as polymer therapeutics for drug delivery.

Novel amphiphilic diblock copolymers, cholesterol-end-capped poly(2-methacryloyloxyethyl phosphorylcholine) (CMPC), which have poly(2-methacryloyloxyethyl phosphorylcholine) (poly(MPC)) as hydrophilic segment and cholesterol as hydrophobic segment, was specially designed as drug delivery systems. Fluorescence probe technique and transmission electron microscope (TEM) characterizations indicated that this novel amphiphilic copolymer formed micelles structure in water and the critical micelle concentration (CMC) was determined to be 1.57 x 10(-7) mol/l. A commercial obtained polymeric amphiphiles, Cholesterol end capped PEO (CPEO), which had a similar structure with CMPC, was used as a control in the cytotoxicity test. While CPEO showed obvious cytotoxicity, cytotoxicity of this novel amphiphiles was not observed as indicated by cell culture. Anti-cancer drug adriamycin (ADR) was incorporated into the micelles by oil-in-water method. The size of the drug-containing micelles was less than 200 nm, and the size distribution of the drug-containing micelles showed a narrow and monodisperse unimodal pattern. The release rate of ADR from the nanosphere was slow and the release continued over 7 days and the release rate decreased with the increase of molecular weights of the copolymer and the amount of the drug entrapped. These experimental results suggested that the nanoparticles prepared from CMPC block copolymers could be a good candidate for injectable drug delivery carrier.

3T3 Cells↗

PubMed2005

Construction and enzymatic degradation of multilayered poly-l-lysine/DNA films.

The layer-by-layer (LbL) self-assembly of poly-l-lysine (PLL) and deoxyribonucleic acid (DNA) was used to construct the enzymatic biodegradable multilayered films. The LbL build up of DNA multilayers was monitored by UV-vis spectrometry, and atomic force microscopy (AFM). AFM, UV-vis spectrometry and fluorescence spectrometry measurements indicated that 90% of DNA within the films was released almost linearly under 5 U mL(-1)alpha-chymotrypsin in PBS at 37 degrees C in 35 h. TEM and zeta potential experiments revealed that the released DNA molecules were condensed into the slight positive complexes with size from 20 to several hundred nanometers. The well-structured, easy processed enzymatic biodegradable multilayered film may have great potential for gene applications in tissue engineering, medical implants, etc.

Biocompatible Materials↗

PubMed2005

Novel biomimetic surfactant: synthesis and micellar characteristics.

Novel biomimetic surfactants based on cholesterol as the hydrophobic segment and poly[2-(methacryloyloxy)ethyl phosphorylcholine] (pMPC) as the hydrophilic segment were synthesized in the present study by atom transfer radical polymerization (ATRP) of 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) using a cholesterol-based macroinitiator. The association behavior of cholesterol-block-poly[2-(methacryloyloxy)ethyl phosphorylcholine] (Chol-pMPCs) in aqueous solution was studied by (1)H NMR spectroscopy, fluorescence probe technique, and atomic force microscopy (AFM). The (1)H NMR spectrum of the polymer in CD(3)OD showed both the cholesterol group and the phosphorylcholine group while the cholesterol group did not appeared in the (1)H NMR spectrum of the polymer in D(2)O, which implied the formation of a micelle structure. Fluorescence excitation spectra of a pyrene probe solubilized in the aggregates of Chol-pMPCs suggested the presence of a critical micelle concentration (cmc) in water. The critical micelle concentrations of the polymers CMPC10, CMPC20 and CMPC40 were determined to be 7.27 x 10(-3), 13.47 x 10(-3), and 20.77 x 10(-3) mg . mL(-1), respectively. AFM images of the aggregates on mica suggested that the pMPC block formed the biocompatible micelle coronas and the cholesterol block formed the hydrophobic micelle cores. These new biomimetic diblock copolymers were evaluated as "stealthy" nanocapsules for the delivery of hydrophobic drugs. The anti-cancer drug adriamycin (ADR) was chosen as a hydrophobic drug to be incorporated into the inner core of the micelles and the morphology of the drug-loaded micelles were observed by AFM.

Biomimetic Materials↗

PubMed2005

Fabrication of thromboresistant multilayer thin film on plasma treated poly (vinyl chloride) surface.

Layer-by-layer deposited anticoagulant multilayer films were prepared on ammonia plasma treated poly (vinyl chloride) (PVC). Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and contact angle results revealed the presence of -NH2 on the ammonia plasma treated PVC surfaces and the layer-by-layer self-assembly process. The stability of multilayer film was studied with the radio labeled method. The remainder bovine serum albumin (BSA) in cross-linked 5(heparin/BSA) multilayer films dipped in phosphate buffered saline (PBS, pH 7.4) was more than 90% in 40 days. The static platelet adhesion result indicated the anticoagulant multilayer films deposited on the plasma treated PVC reduced platelet adhesion drastically and no thrombus forming. The plasma recalcification time revealed that the multilayer modified surfaces greatly prolonged the plasma recalcification time. Such an easy processing and shape-independent method may have good potential for surface modification of cardiovascular devices.

Blood Platelets↗

PubMed2005

The effect of formation of the liquid crystalline phase on the blood compatibility of a cholesterol modified silicone.

Cholesterol modified silicones were synthesized by grafting copolymerization of 10-Cholesteryloxydecanol onto polymethylhydrosiloxane (PMHS). Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance ((1)H-NMR) spectroscopy and gel permeation chromatography (GPC) confirmed the chemical structures of polymers. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) results indicated the mesogenic properties of those polymers. The modified silicone with 45% 10-Cholesteryloxydecanyl (SC45) indicated obvious thermotropic liquid crystalline transform at about 122-124.9 degrees C. The thermotropic liquid crystalline phase could be retained at room temperature via a special annealing/quenching process. The anneal-quenched film (SC45C) formed continuous liquid crystalline phase, whereas the unannealed films presented amorphous structure. The blood compatibility of the coatings was assessed from SEM observation of the platelet's adhesion to coating surface and plasma recalcification time (PRT). The results revealed that the formation of the liquid crystalline phase could greatly improve the in vitro blood compatibility of the materials. The positive results of liquid crystalline onto haemocompatibility allow broad potential in biomaterials.

Biocompatible Materials↗

PubMed2005

Construction of anti-adhesive and antibacterial multilayer films via layer-by-layer assembly of heparin and chitosan.

Chitosan as an antibacterial agent and heparin as an anti-adhesive agent were alternatively deposited onto aminolyzed poly(ethylene terephthalate) (PET) films to construct anti-adhesive and antibacterial multilayer films. The contact-angle and UV data verified the progressive buildup of the multilayer film by alternate deposition of the polyelectrolytes. The properties of multilayer films were investigated by contact angle, atomic force microscopy (AFM), lateral force microscopy (LFM) and UV spectra. The results of initial adhesion of Escherichia coli (E. coli) on PET substrates showed that the number of E. coli adhered onto the control PET was in a much greater extent than onto the chitosan/heparin multilayer films, and the number of adhesive bacteria decreased with a decrease in assembly pH. The in vitro antibacterial test indicated that a multilayer of chitosan/heparin could kill the bacteria effectively. The number of viable bacteria decreased by 7% after 7 h in contact with the control PET films, but by 46-68% for the multilayer-modified PET films. Only 3-8% of the cells were viable for the multilayer-modified PET films after 24h. It is interesting to find the assembly pH has a remarkable effect on the antibacterial property of the multilayer. The number of viable bacteria on the multilayer assembled at pH = 3.8, 2.9 and 6.0 decreased by 68%, 58% and 46%, respectively. Such an easy processing and shape-independent method to prepare an anti-adhesive and antibacterial surface may have good potential for surface modification of cardiovascular devices.

Anti-Bacterial Agents↗

PubMed2005

Comparison of cell-suspension and explant culture of rabbit limbal epithelial cells.

Currently, most investigators directly use limbal explants to culture corneal epithelial cells. However, it has not been identified that limbal stem cells do readily migrate from the limbal explants onto culture plate or amniotic membrane carrier. In this study a cell-suspension culture system for rabbit limbal stem cells was developed and compared with the direct explant method in the aspect of stem cells content in the culture system. Rabbit limbal epithelial cells were dissociated from rabbit eyes by dispase and single cell suspension was made for cell-suspension culture. DeltaNp63 expression of cultured rabbit limbal epithelial cells by cell-suspension technique and explant technique was detected. In cell-suspension culture, isolated cell-suspension was evaluated by flow cytometric analysis for vimentin expression and residual limbal tissue after dispase treatment was examined by scanning electron microscopy. In limbal epithelial cells suspension less than 5% cells were vimentin positive. Examination of residual limbal tissue confirmed that all the limbal epithelial cells had been removed. Histological examination revealed that with cell-suspension culture the cultured epithelial cells could differentiate better than with explant technique. In cells cultured with cell-suspension, there were much more cells expressing DeltaNp63 than in explant cultured cells. In cells cultured with explants, most of DeltaNp63 labelling cells mustered around the explants, and peripheral cells on the slides were DeltaNp63 negative. These results suggested that with pure limbal epithelial cells suspension including basal cells, which could directly enter into culture system, cell-suspension culture technique was significantly superior to explant culture technique in terms of stem cells content.

Animals↗

PubMed2005

Osteoblast growth promotion by protein electrostatic self-assembly on biodegradable poly(lactide).

Extracellular matrix (ECM)-like coating was developed on biodegradable biomaterials based on the electrostatic self-assembly (ESA) technique to promote osteoblast growth. Poly(ethylenimine) (PEI) was first employed to obtain a stable positively charged surface on poly (DL-lactide) (PDL-LA) substrate. Gelatin was selected as ECM-like biomacromolecule to deposit on the activated PDL-LA substrate using the ESA technique. zeta-Potential results showed alternating charge of polyelectrolytes (PEI/gelatin) layering on PDL-LA microspheres. Quartz crystal microbalance (QCM) measurement further verified the gradual deposition of PEI/gelatin on PDL-LA thin film. Osteoblast cells (MC3T3) were chosen to test the cell behavior on modified PDL-LA substrates. The osteoblast test about cell activity, intracellular total DNA content, total protein content and cell morphology by SEM investigation on ECM-like multilayer-modified PDL-LA substrate showed to promote osteoblast growth. Comparing conventional coating methods, polyelectrolyte multilayers are easy and stable to prepare. It may be a good choice for the surface modification of complex biomedical devices. These very flexible systems allow broad medical applications for drug delivery and tissue engineering.

3T3 Cells↗

PubMed2005

[A study on cytocompatibility of poly (lactic acid) membrane modified by polymer microspheres with different surface charges].

Poly(lactic acid) microspheres with different surface charges have been prepared by using cationic, anionic or nonionic surfactants as the microspheres' surface stabilizers. Embedded with these microspheres, the modified PLA membranes with different surface charges have been obtained. The test of stability by CLSM and the morphological test by SEM confirmed that we obtained the microspheres modified PLA membranes with different surface charges successfully. The chondrocyte compatibility test of these modified PLA membranes showed that the attachment, proliferation and activity of chondrocytes on the positive surface of the modified PLA were better than those of other modified PLA membranes. The positive charge on the surface of PLA membrane could improve the cell-compatibility of PLA well.

Animals↗

PubMed2004

Protein electrostatic self-assembly on poly(DL-lactide) scaffold to promote osteoblast growth.

The development of protein coating on 3D biodegradable scaffold based on electrostatic self-assembly (ESA) to promote osteoblast growth is reported. Poly (ethylenimine) (PEI) was employed to obtain a stable positively charged surface on poly(DL-lactide) (PDL-LA) substrate. An extracellular-matrix (ECM)-like biomacromolecule, gelatin, was chosen as the polyelectrolyte to deposit on the activated PDL-LA substrate via ESA technique. Osteoblast (MC3T3) was then cultured on unmodified and gelatin-modified PDL-LA scaffolds. Osteoblast testing regarding total intracellular protein content, total DNA content, cell activity, and cell morphology on the ECM-like multilayer-modified PDL-LA scaffold showed that osteoblast growth was promoted. It will be easy to replace the gelatin with osteoinductive proteins or other polyelectrolytes to promote specific osteoblast functions. In comparison with conventional coating methods, polyelectrolyte multilayers are easy and stable to prepare. They may be a good choice for the surface modification of complex biomedical devices, especially for the 3D tissue-engineering scaffold. These very flexible systems allow broad medical applications for drug delivery and tissue engineering.

3T3 Cells↗

PubMed2004

Fabrication of alternating polycation and albumin multilayer coating onto stainless steel by electrostatic layer-by-layer adsorption.

Multilayer films consisting of polyethylenimine (PEI) and albumin were successfully prepared on biomedical 316L stainless steel surface via electrostatic self-assembly of the PEI and albumin. The process of electrostatic self-assembly of PEI/albumin was monitored by125I radiolabeling, electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). The EIS data revealed that the multilayer coating was stable in Tris-HCl (pH 7.35) buffer solution for 21 days. 125I radiolabeling experiments indicated that less than 10% albumin was eluted by PBS in 45 days. Static platelet adhesion experiments indicated that the PEI/albumin deposited on stainless steel could resist platelet adhesion effectively. Such an easy processing and shape-independent method may have good potential for surface modification of cardiovascular devices.

Adsorption↗

PubMed2004

Surface tailoring of poly(DL-lactic acid) by ligand-tethered amphiphilic polymer for promoting chondrocyte attachment and growth.

The ligand-tethered poly(ethylene oxide-propylene oxide-ethylene oxide) (PEO-PPO-PEO) triblock copolymer was explored to engineer poly(DL-lactic acid) (PDL-LA) material to promote cell attachment and growth. The PEO-PPO-PEO was activated by methyl sulfonyl chloride and the amino acid, and peptide were attached. By blending the PDL-LA with the ligand-tethered PEO-PPO-PEO derivatives, the surface of modified PDL-LA film was investigated by ATR-FTIR, XPS and contact angle. The chondrocytes test on different PDL-LA films indicated that the PEO-PPO-PEO amino acid and RGD derivatives modified PDL-LA films could promote chondrocyte attachment and growth. This simple surface treatment method may have potentials for tissue engineering and other biomedical applications.

Adsorption↗