A Comparison of the Effects of Silica and Hydroxyapatite Nanoparticles on Poly(ε-caprolactone)-Poly(ethylene glycol)-Poly(ε-caprolactone)/Chitosan Nanofibrous Scaffolds for Bone Tissue Engineering

BACKGROUND: The major challenge of tissue engineering is to develop constructions with suitable properties which would mimic the natural extracellular matrix to induce the proliferation and differentiation of cells. Poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC), chitosan (CS), nano-silica (n-SiO₂) and nano-hydroxyapatite (n-HA) are biomaterials successfully applied for the preparation of 3D structures appropriate for tissue engineering. METHODS: We evaluated the effect of n-HA and n-SiO₂ incorporated PCEC-CS nanofibers on physical properties and osteogenic differentiation of human dental pulp stem cells (hDPSCs). Fourier transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscope, thermogravimetric analysis, contact angle and mechanical test were applied to evaluate the physicochemical properties of nanofibers. Cell adhesion and proliferation of hDPSCs and their osteoblastic differentiation on nanofibers were assessed using MTT assay, DAPI staining, alizarin red S staining, and QRT-PCR assay. RESULTS: All the samples demonstrated bead-less morphologies with an average diameter in the range of 190–260 nm. The mechanical test studies showed that scaffolds incorporated with n-HA had a higher tensile strength than ones incorporated with n-SiO₂. While the hydrophilicity of n-SiO₂ incorporated PCEC-CS nanofibers was higher than that of samples enriched with n-HA. Cell adhesion and proliferation studies showed that n-HA incorporated nanofibers were slightly superior to n-SiO₂ incorporated ones. Alizarin red S staining and QRT-PCR analysis confirmed the osteogenic differentiation of hDPSCs on PCEC-CS nanofibers incorporated with n-HA and n-SiO₂. CONCLUSION: Compared to other groups, PCEC-CS nanofibers incorporated with 15 wt% n-HA were able to support more cell adhesion and differentiation, thus are better candidates for bone tissue engineering applications.

Study on the Effect of Hydrophilic/Hydrophobic Nano-silica with Different Adding Amount on the Stability of Glycyrrhetinic Acid Lipo-emulsion / 中国药房

OBJECTIVE:To study the effect of hydrophilic/hydrophobic nano-silica with different adding amount on the stabili-ty of lipo-emulsion. METHODS:Glycyrrhetinic acid lipo-emulsion 4 mL was taken,respectively adding into 0.5%,1.0%,1.5%(m/m,the same below) hydrophilic nSiO2,and 0.4%,0.75,1.0% hydrophobic nSiO2,incubating 2 h in 30 ℃ water;the same batch of Glycyrrhetinic acid lipo-emulsion was treated as blank control. The forms were observed under electron microscopy after treatment,absorbance value was determined,the stability parameter (KE) was calculated according to the absorbance value,then the adding amount of nSiO2 was optimized,3 batches of preparations was prepared,and the verification test was conducted. RE-SULTS:The spherical structure was Glycyrrhetinic acid lipo-emulsion in the electron microscopy,the substance wrapping its sur-face white ring (fully wrapped) or semi-circular structure (not fully wrapped) was nSiO2. KE of hydrophilic nSiO2 were 4.66%, 5.01% and -2.08%,and KE of hydrophobic nSiO2 were 3.02%,4.51% and 7.24%. The optimized adding amount of hydrophilic nSiO2 was 0.2%,0.3% and 0.4%,hydrophobic nSiO2 was 0.1%,0.2% and 0.3%;KE were 6.19%,3.05%,7.84%,8.42%, 2.41%,2.93%,respectively. The optimal adding amount was 0.3% hydrophilic nSiO2 and 0.2% hydrophobic nSiO2;the 3 batches of preparation showed the optimum stability in its own adding amount. CONCLUSIONS:Both hydrophilic and hydrophobic nSiO2 can improve the stability of Glycyrrhetinic acid lipo-emulsion,and preferably 0.3%,0.2%.

Inhibition on proliferation of HeLa cells in vitro of nano sllicon equipped with 4'-demethylepi-podophyllotoxin / 药物评价研究

Objective To study the inhibitory effect on proliferation of Hela cells of podophyllotoxin,4'-demethylepi-podophyllotoxin and drug combination of different proportion of nano-sillca (SiO2) and 4'-demethylepi-podophyllotoxin in vitro,and discuss the mechanism.Methods Used ethyl silicate hydrolysis method to prepare 25 nm SiO2 sample,next carried 4'-demethylepi-podophyllotoxin after the surface modification,and measure cell campatibility by MTT method and Hoechst 33342.The inhibitory effect of podophyllotoxin,4'-demethylepi-podophyllotoxin and drug combination on proliferation of Hela cells was measured by MTT assay.Hoechst 33342 staining method was used to detect cell apoptosis.The effect ofdmg combination treatment on cell morphology was observed by inverted microscope.Western blotting technique was used to detected effect of 4'-demethylepi-podophyllotoxin and drug combination on expression of apoptosis related protein.Results Inhibitory effect onproliferation of Hela cells of 4'-demethylepi-podophyllotoxin is superior to podophyllotoxin,inhibitory effect of drug combination is superior to the single 4'-demethylepi-podophyllotoxin,the inhibition of drug combination with 0.125 μg/mL nano SiO2 and 6.25 μg/mL 4'-demethylepi-podophyllotoxin is the most obvious.MTT and Hoechst 33342 experimental results showed that the 25 nm SiO2 have good cell compatibility.Podophyllotoxin,4'-demethylepi-podophyllotoxin and drug combination can induce apoptosis.Western blotting results showed that 4'-demethylepi-podophyllotoxin and drug combination can up-regulate the ratio of Bax/Bcl-2 and the expression level of Caspase-3、P53 and P38.Conclusion In vitro experimental performance of drug combination is superior to single 4'-demethylepi-podophyllotoxin,it is may by effecting the expression of Bcl-2,Bax,Caspase-3,P53,and P38 and others apoptosis related protein to induce Hela cell apoptosis.

Modification study of cyanoacrylate medical adhesive / 医疗卫生装备

Objective To perform modification study of cyanoacrylate (CA) medical adhesive and to select the optimal mo-difying material and the best ratio.Methods Carboxylic multi-walled carbon nanotubes (MWCNTs-COOH), multi-walled carbon nanotubes (MWCNTs), hydrophobic nano-silica, nitrile rubber, epoxy resin and polymethyl methacrylate (PMMA) were used to modify 5% triclosan/cyanoacrylate antimicrobial adhesive respectively. The bond strength, toughness and viscosity of the modified adhesive were examined in different concentrations.Results 0.064% MWCNTs-COOH, 6% nano-silica, 4% nitrile rubber and 6.4% epoxy resin all had good effects in strength modification. The bond strength were (14.71±1.48)MPa, (14.03±1.92)MPa, (14.6±1.78)MPa and (14.05±1.46)MPa respectively. 8% nano-silica had the lowest Tg of (1.1±0.24)℃ and the strongest viscosity of (15 536.68±28.4)cP. When the nano-silica concentration was 8%, the compound was very viscous and sticky. When the antimicrobial adhesive modified with 6% nano-silica, the bond strength was (14.03±1.92)MPa, the Tg was (3.6±0.68)℃, and the viscosity was (5 278.87±31.68)cP.Conclusion 6% nano-silica is the best modifying material, and has the optimal effect of modification.