Narrow Results

A novel method to prepare crosslinked polyethyleneimine (CPEI) hollow nanospheres was reported. Uniform silica nanospheres were used as templates, 3-aminopropyl trimethoxysilane (APS) was immobilized on the surface of silica nanospheres as couple agent. Aziridine was initiated ring-opening polymerization with the amino groups in APS to form polyethyleneimine (PEI) shell layer. 1,4-Butanediol diacrylate was utilized to crosslink PEI polymeric shell. The silica nanospheres in core were etched by hydrofluoric acid to obtain hollow CPEI nanospheres. The hollow nanospheres were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA).

Zinc oxide (ZnO) nanowire (NW) films were synthesized at low temperature (95°C) through amine-assisted solution process and used as photoanode for the fabrication of dye-sensitized solar cells (DSSCs). It was found that with the addition of polyethyleneimine (PEI) and ammonium hydroxide (NH₄OH) in growth solution, the NWs were smaller in diameter and longer in length by prolonging the growth time without refreshing the growth solution. A reasonable overall conversion efficiency of 1.25% was achieved with photoanode based on ZnO NWs containing PEI and NH₄OH. However, DSSC fabricated with ZnO NWs not containing PEI and NH₄OH showed low conversion efficiency of 0.58%. All the DSSCs exhibited almost similar values of open circuit voltage (V_OC) and fill factor (FF). Interestingly, DSSC based on ZnO NWs with PEI and NH₄OH obtained two times higher short circuit current density (J_SC) compared to ZnO NWs photoanode without PEI and NH₄OH. The increase in efficiency and J_SC with the length of NWs is attributed to the increase in internal surface area for sufficient dye loading and light harvesting.

An apoptosis-related gene loaded to the core–shell delivery system has been fabricated to give effective tumor therapy. The gene delivery system consists of the hydrophobic poly (methyl methacrylate) (PMMA) and plasmid DNA (pDNA) loaded branched polyethyleneimine (PEI). The BBC3 gene is related to cell apoptosis and constructed in the mammal plasmid vector under the CMV promoter for overexpression. The amphiphilic PEI-PMMA nanoparticle (NP) has been developed as a DNA loaded carrier of low cytotoxicity and enhanced stability. The average NP size was 330nm with a narrow distribution. The $+38$mV of the zeta potential in water showed the effect of negatively charged DNA aggregation. Gel retardation assay showed the complete PEI/pDNA (N:P) binding ratio was 125:1. The MCF-7 cancer cell line was transfected with the delivery complexes, followed by the MTT assay to evaluate anti-tumor therapy. The results showed that BBC3 gene loaded PEI-PMMA complexes have significant cancer cell inhibition. Taken together, BBC3 genes expressed after 48h transfection with PEI-PMMA NPs, and this gene therapy delivery system has cancer cells inhibition as low as 8$\mu$g/mL in vitro.

In order to conveniently and rapidly detect Cr³⁺ ions in aqueous solution, novel functionalized gold nanoparticles (AuNPs) were designed with 4-mercaptobenzoic acid (4-MBA) and polyethyleneimine (PEI). In addition, we also compared the response signal of various functional AuNPs to Cr³⁺ ions on the detection system. The modifiers included 4-MBA, 4-nitrobenzene mercaptan (4-NTP) and PEI, respectively. The results showed that 4-MBA and PEI co-functionalized had better sensitiveness than others. Cr³⁺ ions in aqueous solution could be detected by naked eye and UV-Vis absorption spectrum and the limit of detection was 1 μM. The response was found to be proportional to Cr³⁺ ions concentration in the range from 2 μM to 10 μM. The developed platform with high selectiveness was successfully utilized to detect Cr³⁺ ions in simulated samples.