Improving cell penetration of gold nanorods by using an amphipathic arginine rich peptide

Indexación: Scopus.Gold nanorods are highly reactive, have a large surface-to-volume ratio, and can be functionalized with biomolecules. Gold nanorods can absorb infrared electromagnetic radiation, which is subsequently dispersed as local heat. Gold nanoparticles can be used as powerful tools for the diagnosis and therapy of different diseases. To improve the biological barrier permeation of nanoparticles with low cytotoxicity, in this study, we conjugated gold nanorods with cell-penetrating peptides (oligoarginines) and with the amphipathic peptide CLPFFD. Methods: We studied the interaction of the functionalized gold nanorods with biological membrane models (liposomes) by dynamic light scattering, transmission electron microscopy and the Langmuir balance. Furthermore, we evaluated the effects on cell viability and permeability with an MTS assay and TEM. Results and Discussion: The interaction study by DLS, the Langmuir balance and cryo-TEM support that GNR-Arg7 CLPFFD enhances the interactions between GNRs and biological membranes. In addition, cells treated with GNR-Arg7 CLPFFD internalized 80% more nanoparticles than cells treated with GNR alone and did not induce cell damage. Conclusion: Our results indicate that incorporation of an amphipathic sequence into oligoarginines for the functionalization of gold nanorods enhances biological membrane nanoparticle interactions and nanoparticle cell permeability with respect to nanorods functionalized with oligoarginine. Overall, functionalized gold nanorods with amphipathic arginine rich peptides might be candidates for improving drug delivery by facilitating biological barrier permeation.https://www.dovepress.com/improving-cell-penetration-of-gold-nanorods-by-using-an-amphipathic-ar-peer-reviewed-fulltext-article-IJ

Ion pair method to determine the CTAB content in gold nanorods samples

In this work, we report a fast and accessible method for quantification of cetyltrimethylammonium bromide (CTAB) in solutions of gold nanorods (GNRs) by bromophenol blue (BPB) ion-paring formation and spectrophotometric detection. The ion-par method used to quantify CTAB exhibited adequate figures of merit and was applied to the quantification of CTAB present in solutions of GNRs-CTAB and in GNRs-CLPFFD samples obtained by the seed growth method. This type of methodology could be extensive to others surfactants employed for the synthesis of nanoparticles. In addition, this method allows screening CTAB in GNRs samples and consequently would help to know if CTAB concentration is lower than an acceptable cut-off for cell viability analysis

Carbon Nanotubes Electrochemistry Allows the In Situ Evaluation of the Effect of β-Sheet Breakers on the Aggregation Process of β-Amyloid

The inhibition of aggregation and disaggregation effect of a β-sheet breaker was evaluated by in situ electrochemistry of the Aβ 1-42 peptide. The exposition of 10tyr residue was followed using a carbon nanotubes modified glassy carbon electrode immersed directly in the solution. Both processes were studied at a ratio of Aβ/β-sheet breaker of 10μM:100μM which is effective in vitro. This approach was compared with Thioflavin-T-induced fluorescence, gel electrophoresis and electron microscopy results. The results provide new clues about the disposition of the N-terminal residue of Aβ in the structure of small aggregates, fibrils and amorphous aggregates and is promising for screening inhibitors of β-amyloid aggregation. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Stable Conjugates of Peptides with Gold Nanorods for Biomedical Applications with Reduced Effects on Cell Viability

Artículo de publicación ISIGold nanorods used in therapy and diagnosis must be nontoxic and stable in biological media and should be specific for the target. The complete combination of these three factors has hindered the use of gold nanorods as carriers in biological and biomedical applications. In this study, we produced a conjugate of gold nanorods with the peptide CLPFFD that recognizes toxic β-amyloid aggregates present in Alzheimer’s disease, demonstrates colloidal stability, maintains plasmonic properties, and shows no effects on cell viability in the SH-SY5Y cell line. Furthermore, the irradiation of β- amyloid in the presence of the conjugate with near-infrared region irradiation energy reduces the amyloidogenic process reducing also its cytotoxicity. The nanorods were synthesized following the seed-mediated method in cetyltrimethylammonium bromide (CTAB) and were conjugated with the N-terminal cysteine peptide, CLPFFD. The conjugate was exhaustively characterized using different techniques (Absorption spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and zeta potential). The effects on cell viability and cell penetration by transmission electron microscopy of the conjugate were evaluated. The chemisorption of the peptide on the surface of gold nanorods increases their stability and reduces their effects on cell viability

Improving the brain delivery of gold nanoparticles by conjugation with an amphipathic peptide

Background & aims: Gold nanoparticles (GNPs) have promising applications for drug delivery as well as for the diagnosis and treatment of several pathologies, such as those related to the CNS. However, GNPs are retained in a number of organs, such as the liver and spleen. Owing to their negative charge and/or processes of opsonization, GNPs are retained by the reticuloendothelial system, thereby decreasing their delivery to the brain. It is therefore crucial to modify the nanoparticle surface in order to increase its lipophilicity and reduce its negative charge, thus achieving enhanced delivery to the brain. Results: In this article, we have shown that conjugation of 12 nm GNPs with the amphipathic peptide CLPFFD increases the in vivo penetration of these particles to the rat brain. The C(GNP)-LPFFD conjugates showed a smaller negative charge and a greater hydrophobic character than citrate-capped GNPs of the same size. We administered intraperitoneal injections of citrate GNPs and C(GNP)-LPFFD in rats, and determined the gold content in the tissues by neutron activation. Compared with citrate GNPs, the C(GNP)-LPFFD conjugate improved the delivery to the brain, increasing the concentration of gold by fourfold, while simultaneously reducing its retention by the spleen 1 and 2 h after injection. At 24 h, the conjugate was partially cleared from the brain, and mainly accumulated in the liver. The C(GNP)-LPFFD did not alter the integrity of the blood-brain barrier, and had no effect on cell viability

Stable Conjugates of Peptides with Gold Nanorods for Biomedical Applications with Reduced Effects on Cell Viability

Gold nanorods used in therapy and diagnosis must be nontoxic and stable in biological media and should be specific for the target. The complete combination of these three factors has hindered the use of gold nanorods as carriers in biological and biomedical applications. In this study, we produced a conjugate of gold nanorods with the peptide CLPFFD that recognizes toxic β-amyloid aggregates present in Alzheimer’s disease, demonstrates colloidal stability, maintains plasmonic properties, and shows no effects on cell viability in the SH-SY5Y cell line. Furthermore, the irradiation of β-amyloid in the presence of the conjugate with near-infrared region irradiation energy reduces the amyloidogenic process reducing also its cytotoxicity. The nanorods were synthesized following the seed-mediated method in cetyltrimethylammonium bromide (CTAB) and were conjugated with the N-terminal cysteine peptide, CLPFFD. The conjugate was exhaustively characterized using different techniques (Absorption spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and zeta potential). The effects on cell viability and cell penetration by transmission electron microscopy of the conjugate were evaluated. The chemisorption of the peptide on the surface of gold nanorods increases their stability and reduces their effects on cell viability

High-throughput screening identifies small molecule inhibitors of thioesterase superfamily member 1: Implications for the management of non-alcoholic fatty liver disease

Objective: Thioesterase superfamily member 1 (Them1) is a long chain acyl-CoA thioesterase comprising two N-terminal HotDog fold enzymatic domains linked to a C-terminal lipid-sensing steroidogenic acute regulatory transfer-related (START) domain, which allosterically modulates enzymatic activity. Them1 is highly expressed in thermogenic adipose tissue, where it functions to suppress energy expenditure by limiting rates of fatty acid oxidation, and is induced markedly in liver in response to high fat feeding, where it suppresses fatty acid oxidation and promotes glucose production. Them1−/− mice are protected against non-alcoholic fatty liver disease (NAFLD), suggesting Them1 as a therapeutic target. Methods: A high-throughput small molecule screen was performed to identify promising inhibitors targeting the fatty acyl-CoA thioesterase activity of purified recombinant Them1.Counter screening was used to determine specificity for Them1 relative to other acyl-CoA thioesterase isoforms. Inhibitor binding and enzyme inhibition were quantified by biophysical and biochemical approaches, respectively. Following structure-based optimization, lead compounds were tested in cell culture. Results: Two lead allosteric inhibitors were identified that selectively inhibited Them1 by binding the START domain. In mouse brown adipocytes, these inhibitors promoted fatty acid oxidation, as evidenced by increased oxygen consumption rates. In mouse hepatocytes, they promoted fatty acid oxidation, but also reduced glucose production. Conclusion: Them1 inhibitors could prove attractive for the pharmacologic management of NAFLD