Biomedical subjects

Lei Zhai

Publications and source records attributed to Lei Zhai.

6 recordsLinked to original sources

PubMed2006

Nanoporosity-driven superhydrophilicity: a means to create multifunctional antifogging coatings.

Multifunctional nanoporous thin films have been fabricated from layer-by-layer assembled silica nanoparticles and a polycation. The resultant multilayer films were found to exhibit both antifogging and antireflection properties. The antifogging properties are a direct result of the development of superhydrophilic wetting characteristics (water droplet contact angle <5 degrees within 0.5 s or less). The nearly instantaneous sheetlike wetting promoted by the superhydrophilic multilayer prevents light scattering water droplets from forming on a surface. The low refractive index of the multilayer film (as low as 1.22) resulting from the presence of nanopores was found to impart excellent antireflection properties. Glass slides coated on both sides with a nanoporous multilayer film exhibited transmission levels as high as 99.8%. Stable superhydrophilic wetting characteristics were obtained only after a critical number of bilayers were deposited onto a surface. The assembly conditions (solution pH and nanoparticle concentration), as well as the choice of nanoparticle size, were found to strongly influence film properties. It is suggested that the superhydrophilic behavior is driven by the rapid infiltration of water into a 3D nanoporous network created under specific assembly conditions.

Journal Article↗

PubMed2006

Controlled drug release from porous polyelectrolyte multilayers.

Microporous and nanoporous polyelectrolyte multilayer films have been explored as ultrathin coatings for controlled drug release. Ketoprofen and cytochalasin D were successfully loaded into nanoporous films and showed zero-order release kinetics over a period of many days. In addition to homogeneous porous multilayers, heterostructures comprising porous regions stacked alternately with nonporous regions were assembled. The heterostructures behaved as dielectric mirrors, which made it possible to optically monitor the loading process. The effects of varying the number of layers in porous and nonporous regions as well as the pore size on the drug release properties were studied. Nonporous regions in the film had no effect on the release rate or duration of release. The amount of drug released could be tuned by varying the number of layers in the porous regions of films, and the release rate depended on the pore size in the films. Microporous multilayers exhibited a Fickian diffusion of drug that was approximately twice as fast as the corresponding nanoporous films. Finally, cell culture experiments with WT NR6 fibroblasts confirmed that cytochalasin D retained its ability to inhibit mitosis after release from the multilayers.

Animals↗

PubMed2006

Patterned superhydrophobic surfaces: toward a synthetic mimic of the Namib Desert beetle.

The present study demonstrates a surface structure that mimics the water harvesting wing surface of the Namib Desert beetle. Hydrophilic patterns on superhydrophobic surfaces were created with water/2-propanol solutions of a polyelectrolyte to produce surfaces with extreme hydrophobic contrast. Selective deposition of multilayer films onto the hydrophilic patterns introduces different properties to the area including superhydrophilicity. Potential applications of such surfaces include water harvesting surfaces, controlled drug release coatings, open-air microchannel devices, and lab-on-chip devices.

2-Propanol↗

PubMed2005

Chromatin-remodeling factor INI1/hSNF5/BAF47 is involved in activation of the colony stimulating factor 1 promoter.

INI1/hSNF5/BAF47 is a core component of the hSWI/ SNF ATP-dependent chromatin remodeling complex, and it has been implicated in regulating gene expression, cell division and tumorigenesis. We investigated whether INI1/hSNF5/BAF47 functions in activation of the colony stimulating factor 1 (CSF1) promoter in HeLa cells. Overexpression of INI1/hSNF5/BAF47 promoted CSF1 transcription, and siRNA targeting INI1/hSNF5/ BAF47 (siINI1) strongly inhibited the activity of the CSF1 promoter. We demonstrated that all conserved domains of INI1/hSNF5/BAF47 are needed for CSF1 transcription. ChIP experiment showed that INI1/ hSNF5/BAF47 is recruited to the region of the CSF1 promoter. Taken together, these results indicate that INI1/hSNF5/BAF47 is involved in activation of the CSF1 promoter.

Cell Culture Techniques↗

PubMed2005

INI1/hSNF5/BAF47 represses c-fos transcription via a histone deacetylase-dependent manner.

INI1/hSNF5/BAF47 is a core component of the hSWI/SNF ATP-dependent chromatin-remodeling complex. It has been suggested that INI1/hSNF5/BAF47 contributes to the regulation of many genes. In this report, we showed that the overexpression of INI1/hSNF5/BAF47 repressed c-fos promoter activity and endogenous c-fos transcription in 293T cells, and the siRNA targeting INI1/hSNF5/BAF47 (siINI1) reversed the inhibitory effect. Histone deacetylation by histone deacetylases (HDACs) was necessary for the repression of c-fos transcription by INI1/hSNF5/BAF47. HDAC and INI1/hSNF5/BAF47 functioned together to suppress c-fos transcription. ChIP experiments demonstrated that INI1/hSNF5/BAF47 could be recruited to the region of c-fos promoter to reduce histone acetylation. Altogether, these data show that INI1/hSNF5/BAF47 represses c-fos transcription via a histone deacetylase (HDAC)-dependent manner.

Cell Line↗

PubMed2002

Effect of ambient conditions on the antibacterial activity of antibacterial agent based on sodium titanium phosphate.

OBJECTIVE: To investigate the effects of ambient conditions on the antibacterial activity of inorganic antibacterial agent based on sodium titanium phosphate. METHODS: The number of live E. Coli ATCC 44113 was counted after the suspension was shaken and incubated in flask with antibacterial agent under ambient conditions. RESULT: The number of live bacteria increased when the concentration of bacteria increased in the range of 1.2 x 10(2) to 1.2 x 10(8) cfu/ml. The antibacterial activity increased with the increase of ambient temperature in the range of 16 approximately 46 degrees C, showing good antibacterial activity at human body temperature. With the increase of the concentrations of co-existing NaCl and protein, the antibacterial activity was found to decrease at first and level off at 0.01 g/ml and 0.0005 g/ml respectively. CONCLUSION: The antibacterial agent has to be used together with organic antibacterial agent in order to achieve good antibacterial effect when the ambient bacterial concentration is high. The antibacterial agent is promising to be used in the preparation of antibacterial cloth because it is highly effective at body temperature and expected to remain antibacterial in perspiration.

Anti-Bacterial Agents↗