Innovative strategy for treatment of lung cancer: targeted nanotechnology-based inhalation co-delivery of anticancer drugs and siRNA

A tumor targeted mesoporous silica nanoparticles (MSN)-based drug delivery system (DDS) was developed for inhalation treatment of lung cancer. The system was capable of effectively delivering inside cancer cells anticancer drugs (doxorubicin and cisplatin) combined with two types of siRNA targeted to MRP1 and BCL2 mRNA for suppression of pump and nonpump cellular resistance in non-small cell lung carcinoma, respectively. Targeting of MSN to cancer cells was achieved by the conjugation of LHRH peptide on the surface of MSN via poly(ethylene glycol) spacer. The delivered anticancer drugs and siRNA preserved their specific activity leading to the cell death induction and inhibition of targeted mRNA. Suppression of cellular resistance by siRNA effectively delivered inside cancer cells and substantially enhanced the cytotoxicity of anticancer drugs. Local delivery of MSN by inhalation led to the preferential accumulation of nanoparticles in the mouse lungs, prevented the escape of MSN into the systemic circulation, and limited their accumulation in other organs. The experimental data confirm that the developed DDS satisfies the major prerequisites for effective treatment of non-small cell lung carcinoma. Therefore, the proposed cancer-targeted MSN-based system for complex delivery of drugs and siRNA has high potential in the effective treatment of lung cancer.

Labile catalytic packaging of DNA/siRNA: control of gold nanoparticles "out" of DNA/siRNA complexes

A novel approach was developed to efficiently package and deliver nucleic acids with low generation polypropylenimine (PPI) dendrimers by using Au nanoparticles as a "labile catalytic" packaging agent. The gold nanoparticles (Au NPs) helped low generation dendrimers to package nucleic acids into discrete nanoparticles but are not included in the final DNA/siRNA complexes. Therefore it becomes possible to eliminate the potential toxic problems associated with Au NPs by selectively removing the Au NPs from the resulting nucleic acid complexes before their delivery to targeted cells. This is a new concept in using inorganic engineered nanoparticles in nucleic acid packaging and delivery applications. Furthermore, compared to the siRNA nanostructures (mainly randomly aggregated nanofibers) fabricated by low generation dendrimer alone (Generation 3), the siRNA nanoparticles packaged using this novel approach (by Au NPs modified with G3 PPI) can be internalized by cancer cells and the delivered siRNAs can efficiently silence their target mRNA. The efficiency of mRNA silencing by this novel approach is even superior to higher generation dendrimers (Generation 5).

Influence of the electron-cation interaction on electron mobility in dye-sensitized ZnO and TiO2 nanocrystals: a study using ultrafast terahertz spectroscopy

Charge transport and recombination in nanostructured semiconductors are poorly understood key processes in dye-sensitized solar cells. We have employed time-resolved spectroscopies in the terahertz and visible spectral regions supplemented with Monte Carlo simulations to obtain unique information on these processes. Our results show that charge transport in the active solar cell material can be very different from that in nonsensitized semiconductors, due to strong electrostatic interaction between injected electrons and dye cations at the surface of the semiconductor nanoparticle. For ZnO, this leads to formation of an electron-cation complex which causes fast charge recombination and dramatically decreases the electron mobility even after the dissociation of the complex. Sensitized TiO2 does not suffer from this problem due to its high permittivity efficiently screening the charges.

DNA and carbon nanotubes as medicine

The identification of disease-related genes and their complete nucleotide sequence through the human genome project provides us with a remarkable opportunity to combat a large number of diseases with designed genes as medicine. However, gene therapy relies on the efficient and nontoxic transport of therapeutic genetic medicine through the cell membranes, and this process is very inefficient. Carbon nanotubes, due to their large surface areas, unique surface properties, and needle-like shape, can deliver a large amount of therapeutic agents, including DNA and siRNAs, to the target disease sites. In addition, due to their unparalleled optical and electrical properties, carbon nanotubes can deliver DNA/siRNA not only into cells, which include difficult transfecting primary-immune cells and bacteria, they can also lead to controlled release of DNA/siRNA for targeted gene therapy. Furthermore, due to their wire shaped structure with a diameter matching with that of DNA/siRNA and their remarkable flexibility, carbon nanotubes can impact on the conformational structure and the transient conformational change of DNA/RNA, which can further enhance the therapeutic effects of DNA/siRNA. Synergistic combination of the multiple capabilities of carbon nanotubes to deliver DNA/siRNAs will lead to the development of powerful multifunctional nanomedicine to treat cancer or other difficult diseases. In this review, we summarized the current studies in using CNT as unique vehicles in the field of gene therapy.

LHRH-targeted nanoparticles for cancer therapeutics

Synthesis and evaluation of a novel cancer cell's receptor-targeted internally quaternized and surface neutral poly(amidoamine) (PAMAM) generation four dendrimer as well as PAMAM-paclitaxel conjugate are described. The advantages of developed nanocarriers include but are not limited to (1) internal cationic charges for the complexation with small interfering RNA or antisense oligonucleotides and their protection from the degradation in systemic circulation; (2) neutral-modified surface for low cytotoxicity of empty unloaded dendrimers; (3) efficient internalization by cancer cells; and (4) preferential accumulation in the tumor and the prevention of adverse side effects of chemotherapy.

Anti-HER2 IgY antibody-functionalized single-walled carbon nanotubes for detection and selective destruction of breast cancer cells

Background

Nanocarrier-based antibody targeting is a promising modality in therapeutic and diagnostic oncology. Single-walled carbon nanotubes (SWNTs) exhibit two unique optical properties that can be exploited for these applications, strong Raman signal for cancer cell detection and near-infrared (NIR) absorbance for selective photothermal ablation of tumors. In the present study, we constructed a HER2 IgY-SWNT complex and demonstrated its dual functionality for both detection and selective destruction of cancer cells in an in vitro model consisting of HER2-expressing SK-BR-3 cells and HER2-negative MCF-7 cells.

Methods

The complex was constructed by covalently conjugating carboxylated SWNTs with anti-HER2 chicken IgY antibody, which is more specific and sensitive than mammalian IgGs. Raman signals were recorded on Raman spectrometers with a laser excitation at 785 nm. NIR irradiation was performed using a diode laser system, and cells with or without nanotube treatment were irradiated by 808 nm laser at 5 W/cm² for 2 min. Cell viability was examined by the calcein AM/ethidium homodimer-1 (EthD-1) staining.

Results

Using a Raman optical microscope, we found the Raman signal collected at single-cell level from the complex-treated SK-BR-3 cells was significantly greater than that from various control cells. NIR irradiation selectively destroyed the complex-targeted breast cancer cells without harming receptor-free cells. The cell death was effectuated without the need of internalization of SWNTs by the cancer cells, a finding that has not been reported previously.

Conclusion

We have demonstrated that the HER2 IgY-SWNT complex specifically targeted HER2-expressing SK-BR-3 cells but not receptor-negative MCF-7 cells. The complex can be potentially used for both detection and selective photothermal ablation of receptor-positive breast cancer cells without the need of internalization by the cells. Thus, the unique intrinsic properties of SWNTs combined with high specificity and sensitivity of IgY antibodies can lead to new strategies for cancer detection and therapy.

Internally cationic polyamidoamine PAMAM-OH dendrimers for siRNA delivery: effect of the degree of quaternization and cancer targeting

A novel cancer targeted, internally cationic and surface neutral polyamidoamine (PAMAM) dendrimer, was designed, synthesized, and evaluated as a nanocarrier for the targeted intracellular delivery of siRNA. The dendrimer contained a synthetic analog of Luteinizing hormone-releasing hormone as cancer targeting moiety. The proposed delivery system possesses the following advantages: (1) internal cationic charges for complexation with siRNA and enhanced siRNA protection; (2) low cytotoxicity; (3) lesser degree of quaternization offering free tertiary amines for potential proton sponge effect; and (4) targeting specifically to cancer cells for enhancing siRNA uptake and efficiency and potential limitation of adverse side effects of chemotherapy on healthy organs. Both nontargeted and targeted dendrimer-siRNA complexes formed compact nanometer size spherical particles, exhibited very low cytotoxicity even at the higher concentration, and efficiently penetrated cancer cells in vitro. However, only the targeted dendrimer-siRNA complex was able to substantially decrease the expression of a targeted BCL2 gene.