hydroquinone-based-synthesis-of-gold-nanorods

Hydroquinone Based Synthesis of Gold Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the ...

Fondazione Don Carlo Gnocchi ONLUS (Don Carlo Gnocchi Foundation)

A new light-scattering-based method to detect molecular interactions at the surface of low-refractive-index nanoparticles was recently proposed. Water-dispersed nanoparticles functionalized with receptors typical of immature bacteria cell walls were used to study the activity of the antibiotic vancomycin. This method subtly depends on the specific properties of the nanoparticles. Here we discuss, by comparative experiments and through theoretical evaluation, the effects of size, refractive index, electric charge, and dilution on the reliability and accuracy of the method. Quite surprisingly, perfect index matching and minimal size (i.e., maximum surface), which is almost attained in one of the colloids here employed, do not represent the ideal conditions. Rather, we show that a nanoparticle radius of 100 nm and a refractive index slightly below that of water yields the best signal/background amplitude. We also show that repulsive interactions can lead to artifacts in the adsorption isotherm, thus indicating that electrostatic stabilization should be kept at a minimum. The close agreement between the interaction strengths, as measured with two different nanoparticle systems, testifies to the reliability of the method.

Phantom nanoparticles as probes of biomolecular interactions.

In this paper, a straightforward method based on elastic light scattering is shown to provide a sensitive and reliable tool for the quantitative determination of protein-ligand interactions that occur at the surface of suitably designed core-shell nanoparticles. The assay makes use of monodisperse nanocolloids that have minimal optical contrast with the aqueous environment. By properly coating the particles with avidin and oligo(ethylene glycol)-based amphiphiles, we developed a hybrid system that combines the availability of standard ligands with the necessary bioinvisibility towards the accidental adsorption of nonspecific macromolecules. This probe was employed to detect interactions between different kinds of biotinylated proteins, and it revealed high specificity and affinities in the low nanomolar range. In particular, we obtained an efficient avidin anchorage of biotinylated protein A on the surface of the nanoparticles, which we exploited as a functional probe for the rapid, quantitative, picomolar detection of human IgG antibodies. Overall, these light-scattering-based nanosensors appear as a simple and highly informative tool for proteomics studies.

Avidin decorated core-shell nanoparticles for biorecognition studies by elastic light scattering.

An elastic light-scattering-based method that makes use of phantom nanoparticles as a substrate organizer (see illustration) allowed the quantitative evaluation of the molecular recognition events between a series of inactivated mutants of phospholipase D and lysophosphatidylcholine. The results highlight the remarkable effects on binding capability caused by single amino acid substitutions.

Dispersed phantom scatterer technique reveals subtle differences in substrate recognition by phospholipase D inactive mutants.

At present, mammary carcinoma is the second most common type of malignant tumor in adult women after lung cancer, as more than one million women are diagnosed with breast cancer every year. Despite advances in diagnosis and treatment, which have resulted in a decrease in mortality in recent decades, breast cancer remains a major public health problem. One of the most significant unresolved clinical and scientific problems is the occurrence of resistance to clinical treatments and their toxicity (and how to predict, prevent and overcome them). However, the heterogeneity of human breast cancer in terms of genetic features, molecular profiles and clinical behavior represents a constraint obstructing the discovery of a solution to the disease. It is currently considered that the chances of success of therapy may increase if the tumor cells are selectively removed before they can evolve to their mature stages up to metastases production. Therefore, novel and more sensitive diagnostic tools are being developed, with the aim of improving the early and noninvasive detection of rising malignancies and the accuracy of tumor tissue localization. Meanwhile, there is an emerging use of targeted therapies in oncology, depending on the expression of specific proteins or genes present in tumor cells. Among the molecular targets considered for the treatment of breast cancer cells so far, we chose to focus on examples involving overexpression and/or gene amplification of "Human Epidermal growth factor Receptor 2" (HER2) protein. In current studies, various types of nanoparticles conjugated with the anti-HER2 monoclonal antibody, the so-called "trastuzumab", are investigated extensively due to promising results in biological and preclinical applications aimed at improving the treatment of breast cancer. In this paper, we present a critical review of the preparation and use of different kinds of trastuzumab-functionalized nanoparticles, with an emphasis on the therapeutic and diagnostic (theranostic) potential of this generation of hybrid nanoparticles, exploiting the multifaceted mechanisms of action of trastuzumab against malignant cells.

HER2 targeting as a two-sided strategy for breast cancer diagnosis and treatment: Outlook and recent implications in nanomedical approaches.

We present a facile, one-pot procedure for the organic-to-water phase transfer and biofunctionalization of semiconductor nanocrystals (quantum dots, or QDs) which employs a synthetic functional copolymer, namely poly(DMA-NAS-MAPS), consisting of three components: a surface interacting monomer, N,N-dimethylacrylamide (DMA), a chemically reactive monomer, N-acryloyloxysuccinimide (NAS), and a silane monomer, [3-(methacryloyloxy)-propyl]-trimethoxysilane (MAPS). The nanocrystals were transferred to water by exploiting the amphiphilic character of the copolymer backbone. Hydrolyzed MAPS units contributed to improve the solubility of QDs in water, whereas NAS exhibited reactivity toward biomolecules. A solution of streptavidin in phosphate buffer exhibited good dispersion ability leading to a clear and transparent colloidal suspension, indicative of good QD dispersion during phase transfer and purification. Unlike most of the published methods, the proposed functionalization approach does not require coupling agents and multistep reactions.

One-pot phase transfer and surface modification of CdSe-ZnS quantum dots using a synthetic functional copolymer.

Among polymeric nanoparticles designed for cancer therapy, PLGA nanoparticles have become one of the most popular polymeric devices for chemotherapeutic-based nanoformulations against several kinds of malignant diseases. Promising properties, including long-circulation time, enhanced tumor localization, interference with "multidrug" resistance effects, and environmental biodegradability, often result in an improvement of the drug bioavailability and effectiveness. In the present work, we have synthesized 1,7-bis(3,4-dimethoxyphenyl)-5-hydroxyhepta-1,4,6-trien-3-one (ASC-J9) and developed uniform ASC-J9-loaded PLGA nanoparticles of about 120 nm, which have been prepared by a single-emulsion process. Structural and morphological features of the nanoformulation were analyzed, followed by an accurate evaluation of the in vitro drug release kinetics, which exhibited Fickian law diffusion over 10 days. The intracellular degradation of ASC-J9-bearing nanoparticles within estrogen-dependent MCF-7 breast cancer cells was correlated to a time- and dose-dependent activity of the released drug. A cellular growth inhibition associated with a specific cell cycle G2/M blocking effect caused by ASC-J9 release inside the cytosol allowed us to put forward a hypothesis on the action mechanism of this nanosystem, which led to the final cell apoptosis. Our study was accomplished using Annexin V-based cell death analysis, MTT assessment of proliferation, radical scavenging activity, and intracellular ROS evaluation. Moreover, the intracellular localization of nanoformulated ASC-J9 was confirmed by a Raman optical imaging experiment designed ad hoc. PLGA nanoparticles and ASC-J9 proved also to be safe for a healthy embryo fibroblast cell line (3T3-L1), suggesting a possible clinical translation of this potential nanochemotherapeutic to expand the inherently poor bioavailability of hydrophobic ASC-J9 that could be proposed for the treatment of malignant breast cancer.

Antiproliferative effect of ASC-J9 delivered by PLGA nanoparticles against estrogen-dependent breast cancer cells.

In our study, 2D nanopillar arrays with plasmonic crystal properties are optimized for surface-enhanced Raman spectroscopy (SERS) application and tested in a biochemical assay for the simultaneous detection of multiple genetic leukemia biomarkers. The special fabrication process combining soft lithography and plasma deposition techniques allows tailoring of the structural and chemical parameters of the crystal surfaces. In this way, it has been possible to tune the plasmonic resonance spectral position close to the excitation wavelength of the monochromatic laser light source in order to maximize the enhancing properties of the substrate. Samples are characterized by scanning electron microscopy and reflectance measurements and tested for SERS activity using malachite green. Besides, as the developed substrate had been prepared on a simple glass slide, SERS detection from the support side is also demonstrated. The optimized substrate is functionalized with thiol-modified capture oligonucleotides, and concentration-dependent signal of the target nucleotide is detected in a sandwich assay with labeled gold nanoparticles. Gold nanoparticles functionalized with different DNA and various Raman reporters are applied in a microarray-based assay recognizing a disease biomarker (Wilms tumor gene) and housekeeping gene expressions in the same time on spatially separated microspots. The multiplexing performance of the SERS-based bioassay is illustrated by distinguishing Raman dyes based on their complex spectral fingerprints.

Polymer nanopillar-gold arrays as surface-enhanced Raman spectroscopy substrate for the simultaneous detection of multiple genes.

The goal of this work is to develop an innovative approach for the coating of gold nanoparticles (AuNPs) with a synthetic functional copolymer. This stable coating with a thickness of few nanometers provides, at the same time, stabilization and functionalization of the particles. The polymeric coating consists of a backbone of polydimethylacrylamide (DMA) functionalized with an alkyne monomer that allows the binding of azido modified molecules by Cu(I)-catalyzed azide/alkyne 1,3-dipolar cycloaddition (CuAAC, click chemistry). The thin polymer layer on the surface stabilizes the colloidal suspension whereas the alkyne functions pending from the backbone are available for the reaction with azido-modified proteins. The reactivity of the coating is demonstrated by immobilizing an azido modified anti-mouse IgG antibody on the particle surface. This approach for the covalent binding of antibody to a gold-NPs is applied to the development of gold labels in biosensing techniques.

Carlo Morasso

Labion - Laboratory of Nanomedicine and Clinical Biophotonics

Fondazione Don Carlo Gnocchi ONLUS (Don Carlo Gnocchi Foundation)

Hydroquinone Based Synthesis of Gold Nanorods