Synthesis of bio-functional nanoparticles from sono-responsive amino acids using high frequency ultrasound

A simple, one-pot high frequency ultrasonication (490 kHz) methodology to convert hydrophobic and amphipathic amino acids into nanostructures was investigated. The approach involved the oxidative coupling of aromatic amino acids (phenylalanine and tryptophan) in aqueous solutions to form high molecular weight dimers and oligomers. The role of cavitation bubble surface and ultrasonic power to trigger the out-of-equilibrium self-assembly of dimers and trimers to spherical and uniform nanostructures with controlled size has been discussed. The synthesized particles exhibited fluorescence in blue, green and red spectral regions and a strong antioxidant activity

Ultrasonic transformation of antibiotic molecules into a selective chemotherapeutic nanodrug

Ultrasound-based engineering of carrier-free nanodrugs by supramolecular self-assembly has recently emerged as an innovative and environmentally friendly synthetic approach. By applying high-frequency sound waves (490 kHz) in aqueous solutions, the transformation of small chemotherapeutic and antibiotic drug molecules into carrier-free nanodrugs with anticancer and antimicrobial activities was recently achieved. The transformation of the antibiotic drug molecules, i.e., doxycycline, into stable nanodrugs (similar to 130 nm) with selective anticancer activity was achieved without requiring organic solvents, chemical agents, or surfactants. The obtained nanodrug exhibited reactive oxygen species (ROS)-mediated cytotoxicity on human breast cancer (MDA-MB 231 cells) but a negligible antiproliferative effect on healthy fibroblast cells. Imaging by super-resolution microscopy (STORM) provided insights into the intracellular trafficking and endosomal escape of the nanodrugs. Overall, these findings suggest that small antibiotic drugs can be transformed into chemotherapeutic nanodrugs with high selectivity against cancer cells

sono assembly of nanostructures via tyrosine tyrosine coupling reactions at the interface of acoustic cavitation bubbles

The reactive and oscillating surface of cavitation microbubbles acts as a catalytic binding site for the coupling of amphiphilic biomolecules

Sonosynthesis of nanobiotics with antimicrobial and antioxidant properties

Transforming small-molecule antibiotics into carrier-free nanoantibiotics represents an opportunity for developing new multifunctional therapeutic agents. In this study, we demonstrate that acoustic cavitation produced by high-frequency ultrasound transforms the antibiotic doxycycline into carrier-free nanobiotics. Upon sonication for 1 h at 10-15 W cm(-3), doxycycline molecules underwent hydroxylation and dimerization processes to ulti-mately self-assemble into nanoparticles of ~100-200 nm in size. Micrometer sized particles can be also obtained by increasing the acoustic power to 20 W cm(-3). The nanodrugs exhibited antioxidant properties, along with antimicrobial activity against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacterial strains. Our results highlight the feasibility of the ultrasound-based approach for engineering drug molecules into a nanosized formulation with controlled and multiple bio-functionalities

Carrier separation and charge transport characteristics of reduced graphene oxide supported visible-light active photocatalysts.

Extending the absorption to the visible region by tuning the optical band-gap of semiconductors and preventing charge carrier recombination are important parameters to achieve a higher efficiency in the field of photocatalysis. The inclusion of reduced graphene oxide (rGO) support in photocatalysts is one of the key strategies to address the above-mentioned issues. In this study, rGO supported AgI–mesoTiO2 photocatalysts were synthesized using a sonochemical approach. The physical effects of ultrasound not only improved the crystallinity of AgI–mesoTiO2 but also increased the surface area and loading of the AgI–mesoTiO2 nanocomposite on rGO sheets. The low intense oxygen functionalities (C–O–C and COOH groups) peak observed in the high resolution C1s spectrum of a hybrid AgI–mesoTiO2–rGO photocatalyst clearly confirmed the successful reduction of graphene oxide (GO) to rGO. The interfacial charge transfer between the rGO and the p–n junction of heterostructured photocatalysts has decreased the band-gap of the photocatalyst from 2.80 to 2.65 eV. Importantly, the integration of rGO into AgI–mesoTiO2 composites serves as a carrier separation centre and provides further insight into the electron transfer pathways of heterostructured nanocomposites. The individual effects of photo-generated electrons and holes over rGO on the photocatalytic degradation efficiency of rhodamine (RhB) and methyl orange (MO) using AgI–mesoTiO2–rGO photocatalysts were also studied. Our experimental results revealed that photo-generated superoxide (O2−˙) radicals are the main reactive species for the degradation of MO, whereas photo-generated holes (h+) are responsible for the degradation of RhB. As a result, 60% enhancement in MO degradation was observed in the presence of rGO in comparison to that of the pure AgI–mesoTiO2 photocatalyst. This is due to the good electron acceptor and the ultrafast electron transfer properties of rGO that can effectively reduce the molecular oxygen to produce a large amount of reactive O2−˙ radicals. However, in the case of RhB degradation, h+ is the main reactive species which showed a slightly increased photocatalytic activity (12%) in the presence of rGO support where the role of rGO is almost negligible. This study suggests the effective roles of rGO for the degradation of organics, i.e., the rate of photocatalytic degradation also depends on the nature of compound rather than rGO support

Sonocrystallization of Lactose from Whey

Whey is a by-product obtained from the cheese-making industry. This by-product is the primary source of high-value products such as whey protein concentrates and lactose. The partial removal of water from the whey is the first step in the recovery of lactose. Then, lactose in the concentrated whey is forced to crystallize through a cooling stage. This conventional process of crystallization is very slow up to 72 h accompanied by the generation of a mixture of lactose types (α, β, and amorphous) and low yield of lactose. These issues have been addressed through the seeding of lactose, the antisolvent crystallization, and more recently, by the crystallization of lactose assisted with low-frequency power ultrasound. Sonocrystallization is known to have a number of specific features that include the enhancement of the primary and secondary nucleation, as well as the development of smaller crystals with more uniform sizes and higher purity. Nowadays, there are a number of studies that provide relevant information on the effects of ultrasound on lactose crystallization, although some of these effects are still not fully understood. This book chapter discusses the current knowledge on lactose sonocrystallization and describes the basic principles of lactose crystallization and sonocrystallization

Sonoluminescence and sonochemiluminescence from a microreactor

Micromachined pits on a substrate can be used to nucleate and stabilize microbubbles in a liquid exposed to an ultrasonic field. Under suitable conditions, the collapse of these bubbles can result in light emission (sonoluminescence, SL). Hydroxyl radicals (OH*) generated during bubble collapse can react with luminol to produce light (sonochemiluminescence, SCL). SL and SCL intensities were recorded for several regimes related to the pressure amplitude (low and high acoustic power levels) at a given ultrasonic frequency (200 kHz) for pure water, and aqueous luminol and propanol solutions. Various arrangements of pits were studied, with the number of pits ranging from no pits (comparable to a classic ultrasound reactor), to three-pits. Where there was more than one pit present, in the high pressure regime the ejected microbubbles combined into linear (two-pits) or triangular (three-pits) bubble clouds (streamers). In all situations where a pit was present on the substrate, the SL was intensified and increased with the number of pits at both low and high power levels. For imaging SL emitting regions, Argon (Ar) saturated water was used under similar conditions. SL emission from aqueous propanol solution (50 mM) provided evidence of transient bubble cavitation. Solutions containing 0.1 mM luminol were also used to demonstrate the radical production by attaining the SCL emission regions.Comment: http://www.sciencedirect.com/science/article/pii/S1350417712000855; ISSN 1350-417

Chemoenzymatic surface decoration of Nisin-shelled nanoemulsions: novel targeted drug-nanocarriers for cancer applications

Nisin, a peptide used as a natural food preservative, is employed in this work for the development of a novel nanocarrier system. Stable and uniform nisin-shelled nanoemulsions (NSNE) with a diameter of 100 ± 20 nm were successfully prepared using 20 kHz flow-through ultrasonication technique. The NSNE showed limited toxicity, high bactericidal activity and high drug loading capacity (EE 65 % w/w). In addition, the nisin shell was exploited for the site-specific attachment of a recombinantly produced cancer targeting ligand (αHER2LPETG IgG). Employing a unique two phases (bio-click) approach which involved both Sortase A mediated Azide Bioconjugation (SMAB) and Strain Promoted Azide Alkyne Cycloaddition (SPAAC) reactions, targeted NSNE (NSNEDOX-αHER2 IgG) were successfully assembled and loaded with the chemotherapeutic drug Doxorubicin (DOX). Finally, NSNEDOX-αHER2 IgG showed cancer-specific binding and augmented cytotoxicity to HER2 expressing tumour cells

Free Radical Generation from High-Frequency Electromechanical Dissociation of Pure Water

We reveal a unique mechanism by which pure water can be dissociated to form free radicals without requiring catalysts, electrolytes, or electrode contact by means of high-frequency nanometer-amplitude electromechanical surface vibrations in the form of surface acoustic waves (SAWs) generated on a piezoelectric substrate. The physical undulations associated with these mechanical waves, in concert with the evanescent electric field arising from the piezoelectric coupling, constitute half-wavelength "nanoelectrochemical cells" in which liquid is trapped within the SAW potential minima with vertical dimensions defined by the wave amplitude (∼10 nm), thereby forming highly confined polarized regions with intense electric field strengths that enable the breakdown of water. The ions and free radicals that are generated rapidly electromigrate under the high field intensity in addition to being convectively transported away from the cells by the bulk liquid recirculation generated by the acoustic excitation, thereby overcoming mass transport limitations that lead to ion recombination.A.R.R., N.C., and L.Y.Y. acknowledge funding support from the Australian Research Council through Discovery Project (DP180102110); Future Fellowship (FT140100834); and Linkage, Infrastructure, Equipment & Facilities (LE170100023) grant

Preface: Ultrasound in the processing of liquid foods, beverages and alcoholic drinks Preface

Preface: Ultrasound in the processing of liquid foods, beverages and alcoholic drinks Prefac