Efficient extraction of carrageenans from Chondrus crispus for the green synthesis of gold nanoparticles and formulation of printable hydrogels.

The integral utilization of sustainable resources with versatile, efficient and cleaner processes is encouraged. Hydrothermal treatment with subcritical water is a chemical free, tunable and rapid technology providing enhanced yield compared to conventional extraction and was explored for the benign by design extraction and depolymerization of carrageenan from Chondrus crispus. Up to 90% of the seaweed was solubilized operating under nonisothermal regime during heating up to 200 °C and 75.5% crude carrageenan yield was attained at 140 °C. Crude carrageenan could not be precipitated by ethanol from the extracts produced at 180 °C and higher temperatures, but ultrafiltration (100 kDa) of the extract obtained at 160 °C provided comparable recovery yields and similar rheological features to those of the ethanol precipitated product. Operation at 140 °C was preferred based on the higher recovery yield of the biopolymer and the whole extract was suitable for the green synthesis of polycrystalline decahedral quasi-spherical gold nanoparticles with a mean size distribution of 8.4 nm and Z potential value of -40.2 mV. Alternatively, the crude carrageen fraction was used for the formulation of printable biopolymer based gels with suitable mechanical properties, including a relevant gel strength enhancement (about 10-fold) when compared with conventional procedures.

Immunomodulatory and Antitumoral Activity of Gold Nanoparticles Synthesized by Red Algae Aqueous Extracts.

This study reports on the green and cost-efficient synthesis of gold nanoparticles from three different red algae extracts. The nanoparticles synthesized were fully characterized by UV-Vis spectroscopy, HRTEM, and Z-potential. Relevant components occurring in the extracts, such as polysaccharides or phenolic content, were assessed by analytical techniques such as spectrophotometric assays and liquid chromatography. Finally, the antioxidant, antitumoral, and anti-inflammatory potential of both the extracts and the gold nanoparticles synthesized were analyzed in order to determine a possible synergistic effect on the nanoparticles. The results obtained confirmed the obtainment of gold nanoparticles with significant potential as immunotherapeutic agents. The therapeutic potential of these nanoparticles could be higher than that of inert gold nanoparticles loaded with bioactive molecules since the former would allow for higher accumulation into the targeted tissue.

Gold Nanoparticles Synthesized by an Aqueous Extract of Codium tomentosum as Potential Antitumoral Enhancers of Gemcitabine.

Cancer still poses a global threat, since a lot of tumors remain untreatable despite all the available chemotherapeutic drugs, whose side effects, it must also be noted, still raise concerns. The antitumoral properties of marine seaweeds make them a potential source of new, less toxic, and more active antitumoral agents. Furthermore, these natural extracts can be combined with nanotechnology to increase their efficacy and improve targeting. In this work, a Codium tomentosum (CT) aqueous extract was employed for the green synthesis of gold nanoparticles (Au@CT). The complete characterization of Au@CT was performed by UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Zeta potential, electron microscopy, X-ray powder diffraction (XRD), high-performance steric exclusion chromatography (HPSEC), and by the determination of their antioxidant capacity. The antiproliferative activity of Au@CT was then tested in hepatic (HEPG-2) and pancreatic (BxPC-3) cell lines. Their potential capacity as enhancers of gemcitabine, a drug frequently used to treat both types of tumors, was also tested. The activity of Au@CT was compared to the activity of the CT extract alone. A synergistic effect with gemcitabine was proven for HEPG-2. Our results showed that gold nanoparticles synthesized from seaweed extracts with antitumoral activity could be a good gemcitabine enhancer.

Macroalgae to nanoparticles: Study of Ulva lactuca L. role in biosynthesis of gold and silver nanoparticles and of their cytotoxicity on colon cancer cell lines.

Marine bio-resources are being widely studied as an invaluable source of compounds with therapeutic applicability. In particular, macroalgae contain an extended variety of bioactive compounds with different structures and promising biological applications. In this work, Ulva lactuca L. (hereafter UL) was utilyzed for the synthesis of gold and silver nanoparticles. Full characterization by UV-Vis spectroscopy, TEM, HRTEM and STEM miscroscopies, Z Potential and FTIR spectroscopy was performed. The first time in the scientific literature, the composition of carbohydrates of UL extract and their changes observed after nanoparticles synthesis were explored in order to investigate their possible role in the biosynthetic process. The reducing power, total phenolic content and DPPH scavenging activity of UL extract, Au@UL and Ag@UL nanoparticles were determined. The effects of UL extract, Au@UL and Ag@UL were tested in vitro on the colon cancer cell lines HT-29 and Caco-2, on normal primary neonatal dermal fibroblast cell line PCS-201-010, as well as on normal colon cell line CCD-112CoN. Lastly, the apoptotic activity and cellular uptake evaluation was determined for Au@UL and Ag@UL.

Chitosan and silver nanoparticles as pudding with raisins with antimicrobial properties.

Chitosan nanoparticles (CS-NP) containing small silver nanoparticles are reported (Ag@CS-NP). CS-NP was synthesized using tripolyphosphate (TPP) as a polyanionic template. TPP also served to electrostatically attract Ag(+) inside CS-NP, where it was reduced by the terminal glucosamine units of the biopolymer. This procedure is environmental friendly, inexpensive, and permits the synthesis of very small AgNP (0.93-1.7 nm), with only a discrete dependence from the amount of silver nitrate used (5-200mg). The obtained hybrid nanocomposites Ag@CS-NP were characterized by DLS, HRTEM, and HAADF-STEM presenting a mean hydrodynamic diameter of 78 nm. The antimicrobial activity of Ag@CS-NP against Candida glabrata, Sacharomyces cerevisiae, Escherichia coli, Klebsiella pneumoniae, Salmonella, Staphylococcus aureus, and Bacillus cereus corresponded to MIC values lower than for AgNO(3).

Gold nanoparticles enhancing dismutation of superoxide radical by its bis(dithiocarbamato)copper(II) shell.

In the past few years three topics in nanoscience have received great attention: catalytic activity of gold nanoparticles (AuNPs), their electron transfer properties, and magnetism. Although these properties could have much in common no report on their synergism has been published. Here we present 10-nm gold nanoparticles conveniently capped with a mixed self-assembled monolayer containing bis(dithiocarbamato)copper(II) complexes, which dismutate superoxide radical with extremely high efficiency (IC(50) = 0.074 µM). This behavior is interpreted as the result of an electron transfer (ET) process between AuNP core and the analyte when associated to copper(II). The ET process involving a charged AuNP core was detected by EPR and UV-vis spectroscopy.

A copper(II) thiosemicarbazone complex built on gold for the immobilization of lipase and laccase.

A self-assembled monolayer (SAM) of imidazole-2-carbaldehyde thiosemicarbazone (H(2)ImTSC) on gold was formed and characterized by ATR-FTIR, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and X-ray Photoelectron Spectroscopy (XPS). The self-assembly of the ligand through its thioenolate group was confirmed by ToF-SIMS and the presence of XPS peaks at 161.9 (S(2p1/2)) and 163.1eV (S(2p3/2)). The two nitrogen donor atoms of self-assembled HImTSC were able to coordinate (kappa(2)-N,N) copper(II) when set to interact with a CuCl(2) solution upon a second deprotonation of the ligand. This way, two types of modified gold sheets for the immobilization of lipase and laccase were obtained: (a) SAM of the ligand on gold (Au-HImTSC), and (b) SAM of HImTSC with a second monolayer of copper(II) (Au-ImTSC-Cu(II)). The highest immobilization of enzyme was achieved for laccase on Au-ImTSC-Cu(II) according to XPS and enzymatic activity determinations. Copper(II) played a an important recognition role through coordination to the enzyme and/or electrostatic interactions. Nevertheless, the positively charged surface of Au-ImTSC-Cu(II) affected the activity of laccase.