Nano LIFE

Heritable breast cancer syndromes have identified the recognition and processing of DNA double strand breaks as a fundamental vulnerability in the breast epithelium. The role of homology-directed DNA repair is particularly prominent, indicating that this repair pathway is rate-limiting. Although the activities of the tumor suppressor genes underlying heritable breast cancer act in a common pathway of DNA double strand break repair, the specific lesions result in surprisingly different patterns of biomarkers in the breast cancers, suggesting that they arise from different cell types that include the luminal, basal and progenitor cells within the breast epithelium. Therefore, each cell type appears to have distinct underlying vulnerabilities in repair of DNA double strand breaks. While the heterogeneity of targets poses a challenge to develop specific therapies, these pathways also render tumor cells sensitive to drugs targeting double strand break repair pathways offering new options for therapies. As double strand break repair is a common pathway underlying breast cancer risk, therapies that enhance the proficiency of this pathway offer a strategy for chemoprevention.

The activation of magnetic nanoparticles (mNPs) by an alternating magnetic field (AMF) is currently being explored as technique for targeted therapeutic heating of tumors. Various types of superparamagnetic and ferromagnetic particles, with different coatings and targeting agents, allow for tumor site and type specificity. Magnetic nanoparticle hyperthermia is also being studied as an adjuvant to conventional chemotherapy and radiation therapy. This review provides an introduction to some of the relevant biology and materials science involved in the technical development and current and future use of mNP hyperthermia as clinical cancer therapy.

Protein array technology has a tremendous potential in large-scale and high-throughput functional proteomics. The conventional protein array approach, which is based on one-to-one indexing between a known protein and an array position, is however, not applicable for decoding genetic information from unknown expressed protein arrays and thus less practicable for global proteome analysis. To address this issue, we have introduced a novel concept of DNA-linked protein array by adopting a strategy of one-to-one indexing between spatially unknown individual DNA arrays and their encoded protein array products. A set of test DNA arrays of DNA-binding (POU) domain protein, c-Myc-tagged POU domain protein, and green fluorescent protein were randomly patterned on a glass surface and subsequently converted into identifiable protein arrays by simultaneously producing and linking the encoded proteins to their encoding genes using a puromycin-assisted mRNA–protein fusion approach in situ. For concept validation, functional assay was performed by the screening of mRNA–protein fusion arrays against a mixture of anti-cMyc and anti-GFP antibodies. Moreover, this approach also provides an additional advantage to incorporate post-translational modifications into protein arrays. The concept developed here is expected to markedly enhance the application of protein microarrays to the study of functional proteomics.

Nanobiotechnology entails the use of nanosized materials to build structures that can be applied in both biotechnology and medicine. In one vein of this field of study, scientists seek to mimic the wide variety of nanomachines and macromolecular structures that exist in nature and to replicate them in both structure and function. As a most intriguing example, the bacterial virus phi29 uses a self-contained nanomotor to package its DNA after replication. The 30-nm nanomotor contains 12 copies of a protein (gp10) which together form a 3.6-nm central channel through which the genomic DNA passes into the procapsid during viral assembly and exits during infection. This connector has been recently reengineered and embedded into a lipid bilayer, creating a system with tremendous application for DNA detection and characterization through electrophysiological measurement. A second component of the phi29 bacteriophage is an ATP-binding pRNA that forms a hexameric ring to gear the motor. The pRNA has been utilized to construct nanoparticles of dimers, trimers, hexamers and patterned superstructures via the interaction of two interlocking loops. Such structures constructed via bottom-up assembly have been used in the delivery of drugs, siRNA, ribozymes, and genes to specific cells, both in vitro and in vivo. This review summarizes current studies on the structure, function, and mechanism of the phi29 DNA packaging motor, as well as addresses the applications of these motor components in the field of nanobiotechnology.

Many studies have demonstrated that microscale changes to surface chemistry and topography affect cell adhesion, proliferation, differentiation, and gene expression. More recently, studies have begun to examine cell behavior interactions with structures on the nanoscale since in vivo, cells recognize and adhere to cell adhesion receptors that are spatially organized on this scale. These studies have been enabled through various fabrication methods, many of which were initially developed for the semiconductor industry. This review explores cell responses to a variety of controlled topographical and biochemical cues using an assortment of nanoscale fabrication methods in order to elucidate which pattern dimensions are beneficial for controlling cell adhesion and differentiation.

Many imaging technologies based on luminescent proteins have proven useful for detecting protein–protein interactions, tracking cells in mice, and monitoring transcriptional regulation of specific genes. Especially, novel bioluminescent proteins have advanced the study of induced protein interactions and protein modification in live cells and animals. This review focuses on recent developments of bioluminescent probes for quantitative evaluation of specific protein–protein interactions and their spatio-temporal imaging by means of split luciferase complementation techniques. From the comparison between fluorescent and bioluminescent proteins, advantages and drawbacks of the bioluminescence techniques are described.

Carbon nanotubes (CNTs) have properties that promise an exciting role in nervous tissue repair. CNTs are strong, extremely light weight, biocompatible and electrically conductive. A relatively novel form of CNT material, multiple strands of CNTs spun into thread, accentuates the linear geometry of CNTs while retaining electrical conductivity. We propose that CNT thread, which is strong, pliable and readily manipulated, has the potential to support longitudinal growth of nerves after injury, in nervous system prostheses. Towards understanding how CNT materials support nervous tissue regeneration, we examined the in vitro interactions between CNT materials and neural stem cell-containing neurospheres, prepared from newborn mouse cortices. Intact neurospheres attached to pieces of as-grown arrays of CNTs, CNT "ribbon" material pulled from the arrays, and CNT thread. Stem cells differentiated into both neurons and glia under these conditions. Processes and cells aligned with the longitudinal axis of the CNT materials, both with and without coatings. For comparisons, dissociated neurosphere cells were plated on CNT thread, polypropylene surgical suture thread and commercial carbon fibers. Initial cell attachment (within seconds) and attachment at 24 h was greater on CNT thread than on the other fiber types. Stem cells on CNT threads differentiated into neurons and astrocytes over several days, on all fibers. The presence of serum greatly aided the health and spreading of both neurons and astrocytes. These findings demonstrate that CNT materials, in particular the thread form, are viable preparations for neural cell attachment, outgrowth and differentiation.

The oral route is the most common and preferred route of drug delivery in view of its convenience and patient acceptance. However for oral administration of therapeutic proteins, several hurdles have to be overcome. For this purpose the use of polymers, with their ease of modification in physical and chemical properties, are attractive in protein drug carriers. They can protect their therapeutic protein loading from degradation in the gastrointestinal tract, and enhance their bioavailability at targeted sites of the body. In this review, potential and currently used polymers for fabrication of protein delivery systems and their applications for oral administration will be discussed.

Cartilage defects remain one of the most challenging musculoskeletal tissues to treat owing to its poor healing capacity. The lack of sufficient clinical treatments has led to a drive in tissue engineering advancements that combine chondrogenic cells with scaffolds to aid in cartilage regeneration. Nanoscale materials are commonly used in scaffold synthesis because of their ability to mimic the size of extracellular matrix (ECM). This review focuses on the use of nanostructured scaffolds in combination with cells for cartilage tissue engineering. We detail the fabrication methods and materials used to produce nanostructured scaffolds, with a focus on nanofibers and their role in modulating cell biology. Lastly, we discuss various techniques that further functionalize the nanostructured scaffolds to enhance cellular responses.

Surgeons and patients are demanding improved replacements for dysfunctional ossicular bones. Replacement of the entire ossicular chain and positioning the prosthesis between the stapes footplate and the tympanic membrane are of particular challenges. Many materials have been used since the first ossicular replacement; at the present time, the two most widely used materials are titanium and hydroxyapatite. Studies have indicated little difference between these two materials. A variety of novel additions have been added to total ossicular replacement prostheses to overcome limitations associated with conventional prostheses. Testing of novel prosthesis materials and designs over long time intervals is needed in order to validate and expand their usage.

We present a combined computational/experimental study of fluorescent Au nanocluster complexes synthesized using small biological molecules. Using density-functional theory, we calculated the binding energy, HOMO–LUMO gap, charge transfer, and bond length of the ligand–Au nanocluster systems. These calculations suggest the formation of ligand–Au nanocluster complexes. We further simulated the HOMO/LUMO states and the absorption spectra of the complexes. The HOMO and LUMO states of the complexes were confined within the Au nanoclusters, suggesting little ligand intrinsic fluorescence. The simulated absorption spectra agreed reasonably well with the experimental data. The simulation results of different systems demonstrate the strong ligand effects on the fluorescent emissions of ligand–Au nanocluster complexes. Our studies provide valuable information for the rational design of next-generation fluorescent tags.

Silver-poly(methyl methacrylate) nanocomposite thin films were deposited on silicon substrates by means of matrix-assisted pulsed laser deposition. Atomic force microscopy revealed that the surface morphologies of the silver-poly(methyl methacrylate) nanocomposite thin films were dependent on the matrix-assisted pulsed laser evaporation processing parameters. Films produced using 4% (by weight of solvent) silver nanoparticles exhibited the highest antimicrobial activity. Antimicrobial activity of the thin films was dependent on the silver concentration, the microenvironment created by the polymer–silver interaction, and the surface potential.

Fluorescent nanoparticles have received much attention for their potential applications in biology and medicine, such as uses as fluorescence markers or imaging agents. Recently, surface-passivated carbon nanoparticles or "carbon dots" were demonstrated to be brightly fluorescent, thus representing a new platform for nanoscale fluorescent agents. For targeted bioapplications of carbon dots, an understanding of their toxicity behavior is necessary, including issues on potential defunctionalization of the dots in biological systems that might result in the exposure of the nanoscale carbon core. In this work, we performed cytotoxicity evaluations on both precursor carbon nanoparticles and carbon dots, from which the results suggested no significant cytotoxic effects.

Nanotechnology has been extensively explored in the past decade to develop a myriad of functional nanostructures to facilitate the delivery of therapeutic and imaging agents for various medical applications. Liposomes and polymeric nanoparticles represent two primary delivery vehicles that are currently under investigation. While many advantages of these two particle platforms have been disclosed, some intrinsic limitations remain to limit their applications at certain extent. Recently, a new type of nanoparticle platform, named lipid–polymer hybrid nanoparticle, has been developed that combines the positive attributes of both liposomes and polymeric nanoparticles while excluding some of their shortages. This new nanoparticle consists of a hydrophobic polymeric core, a lipid shell surrounding the polymeric core, and a hydrophilic polymer stealth layer outside the lipid shell. In this review, we first introduce the synthesis and surface functionalization techniques of the lipid–polymer hybrid nanoparticle, followed by a review of typical characterization of the particles. We then summarize the current and potential medical applications of this new nanoparticle as a delivery vehicle of therapeutic and imaging agents. Finally we highlight some challenges faced in further developing this robust delivery platform.