Gold nanoprisms as optoacoustic signal nanoamplifiers for in vivo bioimaging of gastrointestinal cancers.

Early detection of cancer greatly increases the chances of a simpler and more effective treatment. Traditional imaging techniques are often limited by shallow penetration, low sensitivity, low specificity, poor spatial resolution or the use of ionizing radiation. Hybrid modalities, like optoacoustic imaging, an emerging molecular imaging modality, contribute to improving most of these limitations. However, this imaging method is hindered by relatively low signal contrast. Here, gold nanoprisms (AuNPrs) are used as signal amplifiers in multispectral optoacoustic tomography (MSOT) to visualize gastrointestinal cancer. PEGylated AuNPrs are successfully internalized by HT-29 gastrointestinal cancer cells in vitro. Moreover, the particles show good biocompatibility and exhibit a surface plasmon band centered at 830 nm, a suitable wavelength for optoacoustic imaging purposes. These findings extend well to an in vivo setting, in which mice are injected with PEGylated AuNPrs in order to visualize tumor angiogenesis in gastrointestinal cancer cells. Overall, both our in vitro and in vivo results show that PEGylated AuNPrs have the capacity to penetrate tumors and provide a high-resolution signal amplifier for optoacoustic imaging. The combination of PEGylated AuNPrs and MSOT represents a significant advance for the in vivo imaging of cancers.

Multifunctional Nanocarriers for diagnostics, drug delivery and targeted treatment across blood-brain barrier: perspectives on tracking and neuroimaging.

Nanotechnology has brought a variety of new possibilities into biological discovery and clinical practice. In particular, nano-scaled carriers have revolutionalized drug delivery, allowing for therapeutic agents to be selectively targeted on an organ, tissue and cell specific level, also minimizing exposure of healthy tissue to drugs. In this review we discuss and analyze three issues, which are considered to be at the core of nano-scaled drug delivery systems, namely functionalization of nanocarriers, delivery to target organs and in vivo imaging. The latest developments on highly specific conjugation strategies that are used to attach biomolecules to the surface of nanoparticles (NP) are first reviewed. Besides drug carrying capabilities, the functionalization of nanocarriers also facilitate their transport to primary target organs. We highlight the leading advantage of nanocarriers, i.e. their ability to cross the blood-brain barrier (BBB), a tightly packed layer of endothelial cells surrounding the brain that prevents high-molecular weight molecules from entering the brain. The BBB has several transport molecules such as growth factors, insulin and transferrin that can potentially increase the efficiency and kinetics of brain-targeting nanocarriers. Potential treatments for common neurological disorders, such as stroke, tumours and Alzheimer's, are therefore a much sought-after application of nanomedicine. Likewise any other drug delivery system, a number of parameters need to be registered once functionalized NPs are administered, for instance their efficiency in organ-selective targeting, bioaccumulation and excretion. Finally, direct in vivo imaging of nanomaterials is an exciting recent field that can provide real-time tracking of those nanocarriers. We review a range of systems suitable for in vivo imaging and monitoring of drug delivery, with an emphasis on most recently introduced molecular imaging modalities based on optical and hybrid contrast, such as fluorescent protein tomography and multispectral optoacoustic tomography. Overall, great potential is foreseen for nanocarriers in medical diagnostics, therapeutics and molecular targeting. A proposed roadmap for ongoing and future research directions is therefore discussed in detail with emphasis on the development of novel approaches for functionalization, targeting and imaging of nano-based drug delivery systems, a cutting-edge technology poised to change the ways medicine is administered.

Surface modification and size dependence in particle translocation during early embryonic development.

Since the mid-1990 s, the number of studies linking air pollutants to preterm and low birth weight, as well as to cardiac birth defects, has grown steadily each year. The critical period in the development of mouse embryos begins with the commencement of gastrulation at day 7.5 of gestation. Our aim is to examine the role of particles size and surface modification in particle translocation during this early embryonic development. Fluorescent polystyrene particles (PS) were employed because they offer an efficient and safe tracking method. Pregnant female mice were sacrificed at 7.5 days of gestation. After cutting open the deciduas, the parietal endoderm was carefully separated and removed. Different sizes of amine- and carboxyl-modified PS beads were injected via the extraembryonic tissue. The embryos were incubated for 12 h, and were investigated under fluorescent microscopy, confocal microscopy, and mesoscopic fluorescence tomography. The results show that 20-nm carboxylic PS distribute in the embryonic and extraembryonic germ layers of ectoderm, mesoderm, and endoderm. Moreover, when the particles are bigger than 100 nm, PS accumulate in extraembryonic tissue, but nevertheless 200-nm amine-modified particles can pass into the embryos. Interestingly, a growth inhibition was observed in the embryos containing nanoparticles. Finally, the stronger translocation effect is associated with amine-modified PS beads (200 nm) instead of the smaller (20 nm, 100 nm) carboxyl ones.

Quantitative analysis of cell adhesion on aligned micro- and nanofibers.

In this study, we quantitatively analyzed the affinity of cell adhesion to aligned nanofibers composed of composites of poly(glycolic acid) (PGA) and collagen. Electrospun composite fibers were fabricated at various PGA/collagen weight mixing ratio (7, 18, 40, 67, and 86%) to generate fibers that ranged in diameter from 10 mum to 500 nm. Scanning electron microscopy (SEM) observation revealed that the PGA/collagen fibers were long and uniformly aligned, irrespective of the PGA/collagen weight mixing ratio. In addition, it was observed that a significantly higher number of NIH3T3 fibroblasts adhered to nanofibers with smaller diameters in comparison to fibers with larger diameters. The highest affinity of cell adhesion was observed in the PGA/collagen fibers with diameter of 500 nm and PGA/collagen weight mixing ratio of 40%. Furthermore, the adherent cells were more elongated on fibers with smaller diameters. Thus, based on the results here, PGA/collagen composite fibers are suitable for tissue culture studies and provide an attractive material for tissue engineering applications.

Cytotoxicity of single-wall carbon nanotubes on human fibroblasts.

We present a toxicological assessment of five carbon nanomaterials on human fibroblast cells in vitro. We correlate the physico-chemical characteristics of these nanomaterials to their toxic effect per se, i.e. excluding catalytic transition metals. Cell survival and attachment assays were evaluated with different concentrations of refined: (i) single-wall carbon nanotubes (SWCNTs), (ii) active carbon, (iii) carbon black, (iv) multi-wall carbon nanotubes, and (v) carbon graphite. The refined nanomaterial that introduced the strongest toxic effect was subsequently compared to its unrefined version. We therefore covered a wide range of variables, such as: physical dimensions, surface areas, dosages, aspect ratios and surface chemistry. Our results are twofold. Firstly, we found that surface area is the variable that best predicts the potential toxicity of these refined carbon nanomaterials, in which SWCNTs induced the strongest cellular apoptosis/necrosis. Secondly, we found that refined SWCNTs are more toxic than its unrefined counterpart. For comparable small surface areas, dispersed carbon nanomaterials due to a change in surface chemistry, are seen to pose morphological changes and cell detachment, and thereupon apoptosis/necrosis. Finally, we propose a mechanism of action that elucidates the higher toxicity of dispersed, hydrophobic nanomaterials of small surface area.

Investigating the role of shape on the biological impact of gold nanoparticles in vitro.

AIM: To investigate the influence of gold nanoparticle geometry on the biochemical response of Calu-3 epithelial cells. MATERIALS & METHODS: Spherical, triangular and hexagonal gold nanoparticles (GNPs) were used. The GNP-cell interaction was assessed via atomic absorption spectroscopy (AAS) and transmission electron microscopy (TEM). The biochemical impact of GNPs was determined over 72 h at (0.0001-1 mg/ml). RESULTS: At 1 mg/ml, hexagonal GNPs reduced Calu-3 viability below 60%, showed increased reactive oxygen species production and higher expression of proapoptotic markers. A cell mass burden of 1:2:12 as well as number of GNPs per cell (2:1:3) was observed for spherical:triangular:hexagonal GNPs. CONCLUSION: These findings do not suggest a direct shape-toxicity effect. However, do highlight the contribution of shape towards the GNP-cell interaction which impacts upon their intracellular number, mass and volume dose.

Characterization of BRCAA1 and its novel antigen epitope identification.

Looking for novel breast cancer antigen epitopes is helpful for its treatment, diagnosis, and prevention. brcaa1 gene is mapped at 1q42.1-q43, its whole genome is 93.857 kb, including 18 exons and 17 introns. BRCAA1 protein is composed of 1,214 amino acids with 10 glycosylate sites, and shares 37% amino acid identity and an identical antigen epitope with Rb binding protein 1. The novel antigen epitope, SSKKQKRSHK, was predicted to locate in the region 610 to 619 sites, was synthesized, and its antibody was fabricated. Competent inhibition analysis showed that SSKKQKRSHK is the shortest effective peptide. The antigen epitope was mapped in the cytoplasm of MCF-7 cells. Immunohistochemistry analysis showed that the antigen epitope exhibited positive expression in 65% (39 of 60) breast cancer specimens and negative expression in 60 non-cancerous tissues. Statistical analysis shows that its expression is closely associated with status of ER and PR, with sensitivity of 100% and specificity of 81%, and confidence interval of 85.9% to 96.9%. ELISA analysis showed that the mean absorbance of sera antibody titers from breast cancer patients and healthy donors were 0401 +/- 0.163 SD and 0.137 +/- 0.121 SD, respectively. Sixty-four percent breast cancer patient sera and 13% healthy donor sera had higher titer than mean titer of healthy donors, and there exists significant difference between breast cancer patients and healthy donors (P < 0.001). In this study, a novel breast cancer antigen epitope, SSKKQKRSHK, is identified. Its expression is associated with characteristics that are themselves associated with prognosis of breast cancer, and its sera antibody level may be helpful for breast cancer diagnosis.

Pulmonary DWCNT exposure causes sustained local and low-level systemic inflammatory changes in mice.

Carbon nanotubes (CNTs) represent promising vectors to facilitate cellular drug delivery and to overcome biological barriers, but some types may also elicit persistent pulmonary inflammation based on their fibre characteristics. Here, we show the pulmonary response to aqueous suspensions of block copolymer dispersed, double-walled carbon nanotubes (DWCNT, length 1-10 µm) in mice by bronchoalveolar lavage (BAL) analysis, and BAL and blood cytokine and lung antioxidant profiling. The intratracheally instilled dose of 50 µg DWCNT caused significant pulmonary inflammation that was not resolved during a 7-day observation period. Light microscopy investigation of the uptake of DWCNT agglomerates revealed no particle ingestion for granulocytes, but only for macrophages. Accumulating macrophage, multinucleated macrophage and lymphocyte numbers in the alveolar region further indicated ineffective resolution with chronification of the inflammation. The local inflammatory impairment of the lung was accompanied by pulmonary antioxidant depletion and haematological signs of systemic inflammation. While the observed inflammation during its acute phase was dominated by neutrophils and neutrophil recruiting cytokines, the contribution of macrophages and lymphocytes with related cytokines became more significant after day 3 of exposure. This study confirms that acute pulmonary toxicity can occur on exposure of high doses of DWCNT agglomerates and offers further insight for improved nanotube design parameters to avoid potential long-term toxicity.