The self-assembled monolayer modification of electrodes - some recent advances in biological application

The modification of an electrode surface at the molecular level using the technique of depositing self-assembled monolayers (SAM) is a typical example of the techniques used in nanotechnology, from the process &quot;bottom up&quot;, which is to create a nanostructure by successive additions of molecular or atomic entities on a surface. This article presents some recent advances in the field, with examples: the development of systems Sat hybridized with biomolecules, nanoparticles or nanotubes in bioelectronics, the use of switchable electrodes to study the adhesion and migration of biological cells , and the integration of molecular son in the SAM to recognize and allow the transduction of a biological response allowing the practice of electrochemistry in a complex biological environment.<br /

Boron Nitride Nanosheets Improve Sensitivity and Reusability of Surface Enhanced Raman Spectroscopy

Surface enhanced Raman spectroscopy (SERS) is a useful multidisciplinary analytic technique. However, it is still a challenge to produce SERS substrates that are highly sensitive, reproducible, stable, reusable, and scalable. Here, we demonstrate that atomically thin boron nitride (BN) nanosheets have many unique and desirable properties to help solve this challenge. The synergic effect of the atomic thickness, high flexibility, stronger surface adsorption capability, electrical insulation, impermeability, high thermal and chemical stability of BN nanosheets can increase the Raman sensitivity by up to two orders, and in the meantime attain long-term stability and extraordinary reusability not achievable by other materials. These advances will greatly facilitate the wider use of SERS in many fields

Attenuated total reflectance fourier transform infrared spectroscopy: an analytical technique to understand therapeutic responses at the molecular level

Rapid monitoring of the response to treatment in cancer patients is essential to predict the outcome of the therapeutic regimen early in the course of the treatment. The conventional methods are laborious, time-consuming, subjective and lack the ability to study different biomolecules and their interactions, simultaneously. Since; mechanisms of cancer and its response to therapy is dependent on molecular interactions and not on single biomolecules, an assay capable of studying molecular interactions as a whole, is preferred. Fourier Transform Infrared (FTIR) spectroscopy has become a popular technique in the field of cancer therapy with an ability to elucidate molecular interactions. The aim of this study, was to explore the utility of the FTIR technique along with multivariate analysis to understand whether the method has the resolution to identify the differences in the mechanism of therapeutic response. Towards achieving the aim, we utilized the mouse xenograft model of retinoblastoma and nanoparticle mediated targeted therapy. The results indicate that the mechanism underlying the response differed between the treated and untreated group which can be elucidated by unique spectral signatures generated by each group. The study establishes the efficiency of non-invasive, label-free and rapid FTIR method in assessing the interactions of nanoparticles with cellular macromolecules towards monitoring the response to cancer therapeutics

Electrochemical metal ion sensors. Exploiting amino acids and peptides as recognition elements

Amino acids and peptides are known to bind metal ions, in some cases very strongly. There are only a few examples of exploiting this binding in sensors. The review covers the current literature on the interaction of peptides and metals and the electrochemistry of bound metal ions. Peptides may be covalently attached to surfaces. Of particular interest is the attachment to gold via sulfur linkages. Sulfur-containing peptides (eg cysteine) may be adsorbed directly, while any amino group can be covalently attached to a carboxylic acid-terminated thiol. Once at a surface, the possibility for using the attached peptide as a sensor for metal ions becomes realised. Results from the authors&rsquo; laboratory and elsewhere have shown the potential for selective monitoring of metal ions at ppt levels. Examples of the use of poly-aspartic acid and the copper binding peptide Gly-Gly-His for detecting copper ions are given.<br /

Epithelial cell adhesion molecule aptamer functionalized PLGA-lecithin-curcumin-PEG nanoparticles for targeted drug delivery to human colorectal adenocarcinoma cells

To improve the efficacy of drug delivery, active targeted nanotechnology-based drug delivery systems are gaining considerable attention as they have the potential to reduce side effects, minimize toxicity, and improve efficacy of anticancer treatment. In this work CUR-NPs (curcumin-loaded lipid-polymer-lecithin hybrid nanoparticles) were synthesized and functionalized with ribonucleic acid (RNA) Aptamers (Apts) against epithelial cell adhesion molecule (EpCAM) for targeted delivery to colorectal adenocarcinoma cells. These CUR-encapsulated bioconjugates (Apt-CUR-NPs) were characterized for particle size, zeta potential, drug encapsulation, stability, and release. The in vitro specific cell binding, cellular uptake, and cytotoxicity of Apt-CUR-NPs were also studied. The Apt-CUR-NP bioconjugates exhibited increased binding to HT29 colon cancer cells and enhancement in cellular uptake when compared to CUR-NPs functionalized with a control Apt (P<0.01). Furthermore, a substantial improvement in cytotoxicity was achieved toward HT29 cells with Apt-CUR-NP bioconjugates. The encapsulation of CUR in Apt-CUR-NPs resulted in the increased bioavailability of delivered CUR over a period of 24 hours compared to that of free CUR in vivo. These results show that the EpCAM Apt-functionalized CUR-NPs enhance the targeting and drug delivery of CUR to colorectal cancer cells. Further development of CUR-encapsulated, nanosized carriers will lead to improved targeted delivery of novel chemotherapeutic agents to colorectal cancer cells

In Vitro Studies of Cells Grown on the Superconductor PrOxFeAs

The recent discovery of arsenic-based high temperature superconductors has reignited interest in the study of superconductor : biological interfaces. However, the new superconductor materials involve the chemistry of arsenic, their toxicity remain unclear [ Nature, 2008, 452(24):922]. In this study the possible adverse effects of this new family of superconductors on cells have been examined. Cell culture studies in conjunction with microscopy and viability assays were employed to examine the influence of arsenic-based superconductor PrOxFeAs (x=0.75) material in vitro. Imaging data revealed that cells were well adhered and spread on the surface of the superconductor. Furthermore, cytotoxicity studies showed that cells were unaffected during the time-course of the experiments, providing support for the biocompatibility aspects of PrOxFeAs-based superconductor material.Comment: Are the FeAs based superconductors toxic

Ionic Liquid-assisted Synthesis of Polyaniline/Gold Nanocomposite and Its Biocatalytic Application

In this report, a novel chemical synthesis of polyaniline/gold nanocomposite is explored using ionic liquid (IL) 1-Butyl-3-methylimidazolium hexafluorophosphate. The direct chemical synthesis of polyaniline/gold nanocomposite was initiated via the spontaneous oxidation of aniline by AuCl4−in IL. A nearly uniform dispersion of polyaniline/Au particles with a diameter of 450 ± 80 nm was produced by this method, which indicates that this method is more suitable for controlling particle dimensions. It was also found that the electrical conductivity of the polyaniline/gold nanocomposite was more than 100 times higher than that of the pure polyaniline nanoparticles. The polyaniline/gold nanocomposite displays superior function in the biocatalytic activation of microperoxidase-11 because of the high surface area of the assembly and the enhanced charge transport properties of the composite material. We also report the possible application of polyaniline/gold nanocomposite as a H2O2biosensor