Gold-Nanoparticle-Based Colorimetric Discrimination of Cancer-Related Point Mutations with Picomolar Sensitivity

Point mutations in the Kirsten rat sarcoma viral oncogene homologue (KRAS) gene are being increasingly recognized as important diagnostic and prognostic markers in cancer. In this work, we describe a rapid and low-cost method for the naked-eye detection of cancer-related point mutations in KRAS based on gold nanoparticles. This simple colorimetric assay is sensitive (limit of detection in the low picomolar range), instrument-free, and employs nonstringent room temperature conditions due to a combination of DNA-conjugated gold nanoparticles, a probe design which exploits cooperative hybridization for increased binding affinity, and signal enhancement on the surface of magnetic beads. Additionally, the scheme is suitable for point-of-care applications, as it combines naked-eye detection, small sample volumes, and isothermal (PCR-free) amplification

Optical Time-Frequency Packing: Principles, Design, Implementation, and Experimental Demonstration

Time-frequency packing (TFP) transmission provides the highest achievable spectral efficiency with a constrained symbol alphabet and detector complexity. In this work, the application of the TFP technique to fiber-optic systems is investigated and experimentally demonstrated. The main theoretical aspects, design guidelines, and implementation issues are discussed, focusing on those aspects which are peculiar to TFP systems. In particular, adaptive compensation of propagation impairments, matched filtering, and maximum a posteriori probability detection are obtained by a combination of a butterfly equalizer and four 8-state parallel Bahl-Cocke-Jelinek-Raviv (BCJR) detectors. A novel algorithm that ensures adaptive equalization, channel estimation, and a proper distribution of tasks between the equalizer and BCJR detectors is proposed. A set of irregular low-density parity-check codes with different rates is designed to operate at low error rates and approach the spectral efficiency limit achievable by TFP at different signal-to-noise ratios. An experimental demonstration of the designed system is finally provided with five dual-polarization QPSK-modulated optical carriers, densely packed in a 100 GHz bandwidth, employing a recirculating loop to test the performance of the system at different transmission distances.Comment: This paper has been accepted for publication in the IEEE/OSA Journal of Lightwave Technolog

Toxicity of citrate-capped AuNPs: an in vitro and in vivo assessment

In this study, we show that 15 nm citrate-capped AuNPs exert a remarkable toxicity in living systems. The assessment was performed by using well-characterized AuNPs, the combination of in vitro and in vivo models (namely two different cell lines and Drosophila melanogaster), exposure to low dosages of nanoparticles (in the sub-nanomolar concentration range), along with the application of several biological assays to monitor different aspects of the toxic effects, such as viability, genotoxicity, and molecular biomarkers

Effects of Cell Culture Media on the Dynamic Formation of Protein−Nanoparticle Complexes and Influence on the Cellular Response

The development of appropriate in vitro protocols to assess the potential toxicity of the ever expanding range of nanoparticles represents a challenging issue, because of the rapid changes of their intrinsic physicochemical properties (size, shape, reactivity, surface area, etc.) upon dispersion in biological fluids. Dynamic formation of protein coating around nanoparticles is a key molecular event, which may strongly impact the biological response in nanotoxicological tests. In this work, by using citrate-capped gold nanoparticles (AuNPs) of different sizes as a model, we show, by several spectroscopic techniques (dynamic light scattering, UV−visible, plasmon resonance light scattering), that proteins−NP interactions are differently mediated by two widely used cellular media (i.e., Dulbecco Modified Eagle's medium (DMEM) and Roswell Park Memorial Institute medium (RPMI), supplemented with fetal bovine serum). We found that, while DMEM elicits the formation of a large time-dependent protein corona, RPMI s..

Mutagenic effects of gold nanoparticles induce aberrant phenotypes in Drosophila melanogaster

Abstract The peculiar physical/chemical characteristics of engineered nanomaterials have led to a rapid increase of nanotechnology-based applications in many fields. However, before exploiting their huge and wide potential, it is necessary to assess their effects upon interaction with living systems. In this context, the screening of nanomaterials to evaluate their possible toxicity and understand the underlying mechanisms currently represents a crucial opportunity to prevent severe harmful effects in the next future. In this work we show the in vivo toxicity of gold nanoparticles (Au NPs) in Drosophila melanogaster , highlighting significant genotoxic effects and, thus, revealing an unsettling aspect of the long-term outcome of the exposure to this nanomaterial. After the treatment with Au NPs, we observed dramatic phenotypic modifications in the subsequent generations of Drosophila , demonstrating their capability to induce mutagenic effects that may be transmitted to the descendants. Noteworthy, we were able to obtain the first nanomaterial-mutated organism, named NM-mut. Although these results sound alarming, they underline the importance of systematic and reliable toxicology characterizations of nanomaterials and the necessity of significant efforts by the nanoscience community in designing and testing suitable nanoscale surface engineering/coating to develop biocompatible nanomaterials with no hazardous effects for human health and environment. From the Clinical Editor While the clinical application of nanomedicine is still in its infancy, the rapid evolution of this field will undoubtedly result in a growing number of clinical trials and eventually in human applications. The interactions of nanoparticles with living organisms determine their toxicity and long-term safety, which must be properly understood prior to large-scale applications are considered. The paper by Dr. Pompa's team is the first ever demonstration of mutagenesis resulting in clearly observable phenotypic alterations and the generation of nano-mutants as a result of exposure to citrate-surfaced gold nanoparticles in drosophila. These groundbreaking results are alarming, but represent a true milestone in nanomedicine and serve as a a reminder and warning about the critical importance of "safety first" in biomedical science

Impact of nanoscale topography on genomics and proteomics of adherent bacteria.

Bacterial adhesion onto inorganic/nanoengineered surfaces is a key issue in biotechnology and medicine, because it is one of the first necessary steps to determine a general pathogenic event. Understanding the molecular mechanisms of bacteria−surface interaction represents a milestone for planning a new generation of devices with unanimously certified antibacterial characteristics. Here, we show how highly controlled nanostructured substrates impact the bacterial behavior in terms of morphological, genomic, and proteomic response. We observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM) that type-1 fimbriae typically disappear in Escherichia coli adherent onto nanostructured substrates, as opposed to bacteria onto reference glass or flat gold surfaces. A genetic variation of the fimbrial operon regulation was consistently identified by real time qPCR in bacteria interacting with the nanorough substrates. To gain a deeper insight into the molecular basis of the interaction mechan..

In Vivo toxicity assessment of gold nanoparticles in Drosophila melanogaster

The growing use of nanomaterials in commercial goods and novel technologies is generating increasing questions about possible risks for human health and environment, due to the lack of an in-depth assessment of their potential toxicity. In this context, we investigated the effects of citrate-capped gold nanoparticles (AuNPs) on the model system Drosophila melanogaster upon ingestion. We observed a significant in vivo toxicity of AuNPs, which elicited clear adverse effects in treated organisms, such as a strong reduction of their life span and fertility, presence of DNA fragmentation, as well as a significant overexpression of the stress proteins. Transmission electron microscopy demonstrated the localization of the nanoparticles in tissues of Drosophila. The experimental evidence of high in vivo toxicity of a nanoscale material, which is widely considered to be safe and biocompatible in its bulk form, opens up important questions in many fields, including nanomedicine, material science, health, drug delivery and risk assessment

Using a Soft Growing Robot as a Sensor Delivery System in Remote Environments: A Practical Case Study

Soft continuum robots are a new class of robotic devices, which are very promising for enabling measurement applications especially in remote, difficult-to-reach environments. In this work, we propose the use of a particular soft robot, which is able to evert and steer from the tip, as a sensor delivery system. The measurement system consists of two major sections: i) the robotic platform for movement purposes; and ii) the sensing part (i.e., a sensor attached to its tip to enable the measurement). As a case study of the use of the soft-growing robot as a sensor-delivery system, the transportation of a wired thermocouple towards a remote hot source was considered. The preliminary results anticipate the suitability of soft continuum robotic platforms for remote applications in confined and constrained environments

Spectral tagging by integrated photonic crystal resonators for highly sensitive and parallel detection in biochips

We propose a technological approach aimed at improving biochips performances, based on an efficient spectral modeling and enhancement of markers fluorescence through the insertion of photonic crystal nanocavities (PhC-NCs) in the readout area of biochips. This strategy univocally associates a specific emission wavelength to a specific bioprobe immobilized on a nanocavity, therefore guaranteeing parallel detection of multiple elements and faster analysis time. Moreover, PhC-NCs significantly enhance the markers fluorescence, thus improving the detection sensitivity

Room-temperature metal stamping by microfluidics

We show the possibility to fabricate highly controlled metal micropatterns on a variety of substrates, such as semiconducting or metallic materials, exploiting a combination of spontaneous galvanic displacement reactions with microfluidics. The process is reliable and quite versatile and allows the fabrication of complex patterns of different metals on a number of substrates in few minutes on a conventional laboratory bench