Divergent approach to nanoscale glycomicelles and photo-responsive supramolecular glycogels. Implications for drug delivery and photoswitching lectin affinity.

The field of stimuli-responsive supramolecular biomaterials has rapidly advanced in recent years, with potential applications in diverse areas such as cancer theranostics, tissue engineering, and catalysis. However, designing molecular materials that exhibit predetermined hierarchical self-assembly to control the size, morphology, surface chemistry, and responsiveness of the final nanostructures remains a significant challenge. In this study, we present a divergent synthetic approach for the fabrication of spherical micelles and functional 1D-glyconanotube-based photoresponsive gels from structurally related diazobenzene/diacetylene glycolipids. The resulting nanostructures were characterized using NMR, TEM, and SEM, confirming the formation of spherical and tubular nanostructures in both the gel and solution states. Upon UV irradiation, a reversible gel-sol transition was observed, resulting from the photoswitching of the azobenzene unit from the stretched trans form to the compact, metastable cis form. Our gels were shown to enable spatio-temporal control of the adhesion and release of the lectin Concanavalin A, demonstrating potential use as regenerable biomaterials to fight against infections with toxins and pathogens. Additionally, our micelles and gels were evaluated as nanocontainers for loading and controlled release of hydrophobic dyes and antitumoural agents, suggesting their possible use as smart theranostic drug delivery systems.

Colorimetric, Naked-Eye Detection of Lysozyme in Human Urine with Gold Nanoparticles.

The stabilizing effect of lysozymes to salt addition over a gold colloid are exploited in order to detect lysozymes in human urine samples. The present research is aimed at the development of a fast, naked-eye detection test for urinary lysozymuria, in which direct comparison with a colorimetric reference, allows for the immediate determination of positive/negative cases. CIEL*a*b* parameters were obtained from sample absorbance measurements, and their color difference with respect to a fixed reference point was measured by calculating the ΔE76 parameter, which is a measure of how well the colors can be distinguished by an untrained observer. Results show that a simple and quick test can reliably, in less than 15 min, give a positive colorimetric response in the naked eye for concentrations of a urinary lysozyme over 57.2 µg/mL. This concentration is well within the limits of that observed for leukemia-associated lysozymurias, among other disorders.

Valorization of Tomato Processing by-Products: Fatty Acid Extraction and Production of Bio-Based Materials.

A method consisting of the alkaline hydrolysis of tomato pomace by-products has been optimized to obtain a mixture of unsaturated and polyhydroxylated fatty acids as well as a non-hydrolysable secondary residue. Reaction rates and the activation energy of the hydrolysis were calculated to reduce costs associated with chemicals and energy consumption. Lipid and non-hydrolysable fractions were chemically (infrared (IR) spectroscopy, gas chromatography/mass spectrometry (GC-MS)) and thermally (differential scanning calorimetry (DSC), thermogravimetric analysis (TGA)) characterized. In addition, the fatty acid mixture was used to produce cutin-based polyesters. Freestanding films were prepared by non-catalyzed melt-polycondensation and characterized by Attenuated Total Reflected-Fourier Transform Infrared (ATR-FTIR) spectroscopy, solid-state nuclear magnetic resonance (NMR), DSC, TGA, Water Contact Angles (WCA), and tensile tests. These bio-based polymers were hydrophobic, insoluble, infusible, and thermally stable, their physical properties being tunable by controlling the presence of unsaturated fatty acids and oxygen in the reaction. The participation of an oxidative crosslinking side reaction is proposed to be responsible for such modifications.

Exploring Factors for the Design of Nanoparticles as Drug Delivery Vectors.

To achieve optimal results when employing nanoparticles in biomedical fields, choosing the right type of nanoparticle and determining the correct procedure for drug loading are key factors. Each type of nanoparticle presents a determined set of characteristics that are, in some cases, unique. In general, their surface charge, geometry or hydrophilic character may be limiting factors, depending on what their intended application is. Once synthesized, additional factors, such as their interaction with biological systems and liberation mechanisms into the target cells, also need to be taken into account. Multiple advantages arise from the use of nanoparticles, such as the capability to solubilize hydrophobic compounds and an increased bioavailability. Those advantages justify the extensive and delicate study that should be undertaken in order to use them as drug delivery agents. One of the most important factors for the design of a drug delivery system with nanoparticles is achieving a high drug-to-nanoparticle ratio. In this Minireview, all of these key factors, both physicochemical and biological, are described, and special emphasis is placed on loading methods employed to introduce drugs into nanoparticles.

Covalent and Non-Covalent DNA-Gold-Nanoparticle Interactions: New Avenues of Research.

The interactions of DNA, whether long, hundred base pair chains or short-chained oligonucleotides, with ligands play a key role in the field of structural biology. Its biological activity not only depends on the thermodynamic properties of DNA-ligand complexes, but can and often is conditioned by the formation kinetics of those complexes. On the other hand, gold nanoparticles have long been known to present excellent biocompatibility with biomolecules and are themselves remarkable for their structural, electronic, magnetic, optical and catalytic properties, radically different from those of their counterpart bulk materials, and which make them an important asset in multiple applications. Therefore, thermodynamic and kinetic studies of the interactions of DNA with nanoparticles acting as small ligands are key for a better understanding of those interactions to allow for their control and modulation and for the opening of new venues of research in nanomedicine, analytic and biologic fields. The interactions of gold nanoparticles with both DNA polymers and their smaller subunits; special focus is placed on those interactions taking place with nonfunctionalized gold nanoparticles are reviewed in the present work.

Assessing the hyperthermic properties of magnetic heterostructures: the case of gold-iron oxide composites.

Gold-iron oxide composites were obtained by in situ reduction of an Au(III) precursor by an organic reductant (either potassium citrate or tiopronin) in a dispersion of preformed iron oxide ultrasmall magnetic (USM) nanoparticles. X-ray diffraction, transmission electron microscopy, chemical analysis and mid-infrared spectroscopy show the successful deposition of gold domains on the preformed magnetic nanoparticles, and the occurrence of either citrate or tiopronin as surface coating. The potential of the USM@Au nanoheterostructures as heat mediators for therapy through magnetic fluid hyperthermia was determined by calorimetric measurements under sample irradiation by an alternating magnetic field with intensity and frequency within the safe values for biomedical use. The USM@Au composites showed to be active heat mediators for magnetic fluid hyperthermia, leading to a rapid increase in temperature under exposure to an alternating magnetic field even under the very mild experimental conditions adopted, and their potential was assessed by determining their specific absorption rate (SAR) and compared with the pure iron oxide nanoparticles. Calorimetric investigation of the synthesized nanostructures enabled us to point out the effect of different experimental conditions on the SAR value, which is to date the parameter used for the assessment of the hyperthermic efficiency.

Nonfunctionalized Gold Nanoparticles: Synthetic Routes and Synthesis Condition Dependence.

Since Faraday first described gold sol synthesis, synthetic routes to nanoparticles, as well as their applications, have experienced a huge growth. Variations in synthesis conditions such as pH, temperature, reduction, and the stabilizing agent used will determine the morphology, size, monodispersity, and stability of nanoparticles obtained, allowing for modulation of their physical and chemical properties. Although many studies have been made about the synthesis and characterization of individual nanosystems of interest, to our knowledge the common, general traits that all those synthesis share have not been previously compiled. In this review, we aim to offer a global vision of some of the most relevant synthetic procedures reported up to date, with a special focus on nonfunctionalized gold nanoparticle synthetic routes in aqueous media, and to display a broad overview of the influence that synthesis conditions have on the shape, stability, and reactivity of nanoparticle systems.

PEGylated versus non-PEGylated magnetic nanoparticles as camptothecin delivery system.

Camptothecin (CPT; (S)-(+)-4-ethyl-4-hydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14-(4H,12H)-dione) is a highly cytotoxic natural alkaloid that has not yet found use as chemotherapeutic agent due to its poor water-solubility and chemical instability and, as a consequence, no effective administration means have been designed. In this work, camptothecin has been successfully loaded into iron oxide superparamagnetic nanoparticles with an average size of 14 nm. It was found that surface modification of the nanoparticles by polyethylene glycol enables loading a large amount of camptothecin. While the unloaded nanoparticles do not induce apoptosis in the H460 lung cancer cell line, the camptothecin-loaded nanoparticle formulations exhibit remarkable pro-apoptotic activity. These results indicate that camptothecin retains its biological activity after loading onto the magnetic nanoparticles. The proposed materials represent novel materials based on naturally occurring bioactive molecules loaded onto nanoparticles to be used as chemotherapeutic formulations. The procedure seems apt to be extended to other active molecules extracted from natural products. In addition, these materials offer the potential of being further implemented for combined imaging and therapeutics, as magnetic nanoparticles are known to be multifunctional tools for biomedicine.

Chemical synthesis and characterization of silver-protected vasoactive intestinal peptide nanoparticles.

UNLABELLED: We characterized a method to conjugate functional silver nanoparticles with vasoactive intestinal peptide (VIP), which could be used as a working model for further tailor-made applications based on VIP surface functionality. Despite sustained interest in the therapeutic applications of VIP, and the fact that its drugability could be largely improved by the attachament to functionalized metal nanoparticles, no methods have been described so far to obtain them. MATERIALS & METHODS: VIP was conjugated to tiopronin-capped silver nanoparticles of a narrow size distribution, by means of proper linkers, to obtain VIP functionalized silver nanoparticles with two different VIP orientations (Ag-tiopronin-PEG-succinic-[His]VIP and Ag-tiopronin-PEG-VIP[His]). VIP intermediate nanoparticles were characterized by transmission-electron microscopy and Fourier transform infrared spectroscopy. VIP functionalized silver nanoparticles cytotoxicity was determined by lactate dehydrogenase release from mixed glial cultures prepared from cerebral cortices of 1-3 days-old C57/Bl mice. Cells were used for lipopolysaccharide stimulation at day 18-22 of culture. RESULTS: Two different types of VIP-functionalized silver nanoparticles were obtained; both expose the C-terminal part of the neuropeptide, but in the first type VIP is attached to silver nanoparticle through its free amine terminus (Ag-tiopronin-PEG-succinic-[His]VIP), while in the second type, VIP N-terminus remains free (Ag-tiopronin-PEG-VIP[His]). VIP-functionalized silver nanoparticles did not compromise cellular viability and inhibited microglia-induced stimulation under inflammatory conditions. CONCLUSION: The chemical synthesis procedure developed to obtain VIP-functionalized silver nanoparticles rendered functional products, in terms of biological activity. The two alternative orientations designed, reduced the constraints for chemical synthesis that depends on the nanosurface to be functionalized. Our study provides, for the first time, a proof of principle to enhance the therapeutic potential of VIP with the valuable properties of metal nanoparticles for imaging, targeting and drug delivery.

Tiopronin monolayer-protected silver nanoparticles modulate IL-6 secretion mediated by Toll-like receptor ligands.

AIMS: Capped silver nanoparticles that can be coupled to a variety of molecules and biomolecules are of great interest owing to their potential applications in biomedicine. However, there are no data about their toxicity or functional effects on a key innate immune response, such as IL-6 secretion, after the engagement of the main group of pathogen-associated molecular patterns receptors, that is, the Toll-like receptors (TLRs). MATERIALS & METHODS: N-(2-mercaptopropionyl)glycine (tiopronin)-capped silver (Ag@tiopronin) nanoparticles of a narrow sized distribution ( approximately 5 nm) were synthesized and characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, Raman, (1)H-NMR and total correlation spectroscopy. Cytotoxicity was determined by lactate deshidrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium assays in Raw 264.7 macrophages. IL-6 was measured by ELISA. RESULTS & DISCUSSION: Ag@tiopronin nanoparticles have a narrow size distribution ( approximately 5 nm), high solubility and stability in aqueous environment with no cytotoxicity in terms of mitochondrial function or plasma-membrane integrity at concentrations as high as 200 microg/10(6) cells. Ag@tiopronin nanoparticles were not proinflammatory agents, but remarkably they specifically impaired the IL-6 secretion mediated by TLR2, TLR2/6, TLR3 or TLR9 stimulation in co-treatment experiments. However, in pretreatment experiments, nanoparticles enhanced the susceptibility of macrophages to inflammatory stimulation mediated by TLR2/1 and TLR2/6 specific ligands while severely impairing the IL-6 secretion activated by the TLR3 or TLR9 ligands. CONCLUSIONS: Contrary to what is found for bare silver nanoparticles, Ag@tiopronin nanoparticles are noncytotoxic to macrophages. Ag@tiopronin nanoparticles showed differential effects on TLR signaling of a high degree of specificity, without proinflammatory effects by themselves. These effects have to be borne in mind when using bioconjugates of Ag@tiopronin nanoparticles for future medical applications.