Antibody-functionalized nano test tubes target breast cancer cells

Universal Method to Transfer Membrane-Templated Nano-Objects to Aqueous Solutions

A wide range of nano-objects are synthesized by combining template synthesis, using polycarbonate membrane as template, with different material deposition methods. The resulting nanostructures varied from robust inorganic gold nanowires grown by electrodeposition to rigid polypyrrole nanotubes synthesized by chemical polymerization and softer nanotubes made of different combinations of synthetic and natural polyelectrolytes fabricated by layer-by-layer (LbL) assembly. The morphology of these various nano-objects is characterized prior to and after their immersion in water, revealing that the rigidity degree of LbL nanotubes strongly decreases after being in contact with water, leading to highly swollen and flexible nanotubes in aqueous solution that tend to stick to any surface and are very difficult to collect and disperse quantitatively in aqueous solution. Different processes to collect these nano-objects and disperse them in aqueous medium for further analysis and application were then studied. Among them, a method based on simple filtration of nanotubes in the presence of a powdered dextran adjuvant leads to the quantitative collection and dispersion in water of all types of tested cylindrical nano-objects. This universal method to efficiently collect membrane templated nano-objects paves the way to further characterization of a large variety of nanotubes in aqueous solution and to their potential use as cargo nanocarriers or as nanoreactors.

Fabrication and modification of composite silica nano test tubes for targeted drug delivery

Drug containing composite silica nano test tubes were fabricated within alumina template membranes, and upon liberation, modified with targeting moieties to specifically kill cancer cells.

Nanowire pellicles for eukaryotic cells: nanowire coating and interaction with cells

AIM

To construct a new robust nanowire-based pellicle for eukaryotic cells, to investigate the interactions between nanowires (NWs) and cell surfaces and the internalization of nanowires, and to demonstrate for isolation of the plasma membrane with improved enrichment of transmembrane proteins.

MATERIALS & METHODS

Silica NWs were coated with alumina to give positive charges on their surface. Multiple myeloma cells were coated with the positively charged NWs by dropping the cells into a buffered suspension of NWs. After the NW-coated cells were lysed, plasma membrane fragments were enriched by differential centrifugation for proteomic studies.

RESULTS

Here we demonstrate complete cell coating with positively charged, alumina-coated silica NWs via nonspecific electrostatic interactions, and characterize a robust pellicle and little/no uptake of NWs.

CONCLUSION

Robust pellicles provide a new platform for therapeutic, diagnostic and biochemical interactions of nanostructures with eukaryotic cells.

Preparing amorphous hydrophobic drug nanoparticles by nanoporous membrane extrusion

Aim: The aim of the present study was to develop a simple and straightforward method for formulating hydrophobic drugs into nanoparticulate form in a scalable and inexpensive manner. Materials & methods: The nanoporous membrane extrusion (NME) method was used to prepare hydrophobic drug nanoparticles. NME is based on the induced precipitation of drug-loaded nanoparticles at the exits of nanopores. Three common hydrophobic drug models (silymarin, β-carotene and butylated hydroxytoluene) were tested. The authors carefully investigated the morphology, crystallinity and dissolution profile of the resulting nanoparticles. Results: Using NME, the authors successfully prepared rather uniform drug nanoparticles (∼100 nm in diameter). These nanoparticles were amorphous and show an improved dissolution profile compared with untreated drug powders. Conclusion: These studies suggest that NME could be used as a general method to produce nanoparticles of hydrophobic drugs.

Original submitted 8 June 2011; Revised submitted 7 May 2012; Published online 3 September 2012

Template synthesis of test tube nanoparticles using non-destructive replication

Nano test tubes are a promising delivery vehicle for a range of therapeutics, including small molecule drugs and biologics. However, current template synthesis methods of producing nano test tubes are prohibitively expensive and time consuming. Here, non-destructive template replication was used to increase nano test tube yield from porous alumina by more than a hundredfold. We demonstrate how to produce nano test tubes of several sizes and compositions, including hybrid tubes with different inner and outer surfaces for targeted surface chemistry. Nano test tubes were readily suspended and stored in aqueous solutions without the need for chemical treatment. These nano test tubes should find application as delivery vehicles for therapeutics, particularly for processive 'bionanoreactors' loaded with enzymes.

Impact of silica nanoparticle design on cellular toxicity and hemolytic activity

Understanding the toxicity of silica nanoparticles (SiO(2)) on the cellular level is crucial for rational design of these nanomaterials for biomedical applications. Herein, we explore the impacts of geometry, porosity, and surface charge of SiO(2) on cellular toxicity and hemolytic activity. Nonporous Stöber silica nanospheres (115 nm diameter), mesoporous silica nanospheres (120 nm diameter, aspect ratio 1), mesoporous silica nanorods with aspect ratio of 2, 4, and 8 (width by length 80 × 200 nm, 150 × 600 nm, 130 × 1000 nm), and their cationic counterparts were evaluated on macrophages, lung carcinoma cells, and human erythrocytes. It was shown that the toxicity of SiO(2) is cell-type dependent and that surface charge and pore size govern cellular toxicity. Using inductively coupled plasma mass spectrometry, the cellular association of SiO(2) was quantitated with the association amount increasing in the following order: mesoporous SiO(2) (aspect ratio 1, 2, 4, 8) < amine-modified mesoporous SiO(2) (aspect ratio 1, 2, 4, 8) < amine-modified nonporous Stöber SiO(2) < nonporous Stöber SiO(2). Geometry did not seem to influence the extent of SiO(2) association at early or extended time points. The level of cellular association of the nanoparticles was directly linked to the extent of plasma membrane damage, suggesting a biological cause-and-effect relationship. Hemolysis assay showed that the hemolytic activity was porosity- and geometry-dependent for bare SiO(2) and surface-charge-dependent for amine-modified SiO(2). A good correlation between hemolytic activity and cellular association was found on a similar dosage basis. These results can provide useful guidelines for the rational design of SiO(2) in nanomedicine.

Fabrication of biodegradable nano test tubes by template synthesis

Aims: Recent publications have suggested that cylindrically shaped drug-delivery carriers have an advantage over carriers based on spherical particles in both blood circulation and cell internalization rates. For this reason, this article introduces a method to fabricate hollow, uniform, biodegradable chitosan nano test tubes for applications in drug delivery. Methods: A nanoporous alumina template membrane was used to fabricate hollow chitosan nano test tubes. The chitosan nano test tubes were crosslinked with a disulfide cleavable crosslinker before being removed from the alumina template membrane. We explored two mechanisms for degrading the chitosan nano test tubes – enzymatic degradation by lysozyme and cleavage of the disulfide bond in the crosslinking agent. Results: The template synthesis method resulted in the fabrication of uniform hollow chitosan nano test tubes whose dimensions were easily manipulated based on the dimensions of the pores in the alumina template membrane. The tubes were degraded upon exposure to either lysozyme or sulfhydryl-containing reducing reagents. Conclusion: These tubes have potential for drug-delivery applications. The fact that these tubes degrade upon exposure to a sulfhydryl-containing reducing agent allows for a mechanism for intercellular drug delivery as the tubes should degrade in the presence of intercellular glutathione.

General method for producing organic nanoparticles using nanoporous membranes

Two liquids are separated by a nanoporous membrane and one liquid is made to flow into the other, causing nanoparticles to be formed at the exits of the nanopores. In particular, we report the generation of nanoparticles of the biodegradable polysaccharide polymer chitosan by placing the chitosan in a low pH aqueous solution that is flowed into a high pH aqueous solution. The size of the nanoparticles (5-20 nm) can be roughly controlled by choosing the size of the nanopores and the pumping rate. In addition, it is possible to load the chitosan nanoparticles with drug molecules, which is demonstrated by incorporation of up to 3.3% rhodamine 6G molecules in the chitosan nanoparticles.

Shape-coded silica nanotubes for multiplexed bioassay: rapid and reliable magnetic decoding protocols

AIMS

The recent development of 1D barcode arrays has proved their capabilities to be applicable to highly multiplexed bioassays. This article introduces two magnetic decoding protocols for suspension arrays of shape-coded silica nanotubes to process multiplexed assays rapidly and easily, which will benefit the minimization and automation of the arrays.

METHODS

In the first protocol, the magnetic nanocrystals are incorporated into the inner voids of barcoded silica nanotubes in order to give the nanotubes magnetic properties. The second protocol is performed by trapping the barcoded silica nanotubes onto streptavidin-modified magnetic beads.

RESULTS

The rapid and easy decoding process was demonstrated by applying the above two protocols to multiplexed assays, resulting in high selectivity. Furthermore, the magnetic bead-trapped barcode nanotubes provided a great opportunity to exclude the use of dye molecules in multiplexed assays by using barcode nanotubes as signals.

CONCLUSION

The rapid and easy manipulation of encoded carriers using magnetic properties could be used to develop promising suspension arrays for portable bioassays.

Mechanical capping of silica nanotubes for encapsulation of molecules

Multifunctional silica nanotubes (SNTs) are being widely used for many biomedical applications due to their structural benefits. Controlling the structure of the open end of an SNT is a crucial step for drug/gene delivery and for fabrication of multifunctional SNTs. We developed a mechanical capsulation method to fabricate caps at the ends of SNTs. A thin layer of malleable capping materials (Au, Ag, PLGA) was deposited onto the surface of an SNT-grown AAO template. Capped SNTs were then obtained by hammering with alumina microbeads. For a proof-of-concept experiment, we demonstrated dye-encapsulated SNTs without any chemical functionalizations. Since a mechanical approach is free of the issue of chemical compatibility between cargo molecules and capping materials, the method can provide an effective platform for the preparation of smart multifunctional nanotubes for biomedical applications.