Ultrasound and photochemical procedures for nanocatalysts preparation: application in photocatalytic biomass valorization.

Nano-photocatalysis is becoming increasingly important due to its multiple applications and multidisciplinary aspects. Applications such as water/air purification, solar energy storage, chemicals production and optoelectronics are some of the most promising. In recent years, the development of novel environmental friendly and cost efficient methods for materials preparation that could replace the old ones is on demand. Unconventional and "soft" techniques such as sonication and photochemistry offer huge possibilities for the synthesis of a broad spectrum of nanostructured materials (e.g., nano-photocatalysts). In the present study, I focus on ultrasound and photochemical procedures for the preparation of nanostructured photocatalysts (e.g., supported metals, metal oxides) and their application in food organic wastes valorization.

Ultrasound-mediated drug/gene delivery in solid tumor treatment.

Ultrasound is an emerging modality for drug delivery in chemotherapy. This paper reviews this novel technology by first introducing the designs and characteristics of three classes of drug/gene vehicles, microbubble (including nanoemulsion), liposomes, and micelles. In comparison to conventional free drug, the targeted drug-release and delivery through vessel wall and interstitial space to cancerous cells can be activated and enhanced under certain sonication conditions. In the acoustic field, there are several reactions of these drug vehicles, including hyperthermia, bubble cavitation, sonoporation, and sonodynamics, whose physical properties are illustrated for better understanding of this approach. In vitro and in vivo results are summarized, and future directions are discussed. Altogether, ultrasound-mediated drug/gene delivery under imaging guidance provides a promising option in cancer treatment with enhanced agent release and site specificity and reduced toxicity.

Lithotripsy.

Shock wave lithotripsy (SWL) is the process of fragmentation of renal or ureteric stones by the use of repetitive shock waves generated outside the body and focused onto the stone. Following its introduction in 1980, SWL revolutionized the treatment of kidney stones by offering patients a non-invasive procedure. It is now seen as a mature technology and its use is perceived to be routine. It is noteworthy that, at the time of its introduction, there was a great effort to discover the mechanism(s) by which it works, and the type of sound field that is optimal. Although nearly three decades of subsequent research have increased the knowledge base significantly, the mechanisms are still controversial. Furthermore there is a growing body of evidence that SWL results in injury to the kidney which may have long-term side effects, such as new onset hypertension, although again there is much controversy within the field. Currently, use of lithotripsy is waning, particularly with the advent of minimally invasive ureteroscopic approaches. The goal here is to review the state of the art in SWL and to present the barriers and challenges that need to be addressed for SWL to deliver on its initial promise of a safe, effective, non-invasive treatment for kidney stones.

Sonoporation, drug delivery, and gene therapy.

Ultrasound is a very effective modality for drug delivery and gene therapy because energy that is non-invasively transmitted through the skin can be focused deeply into the human body in a specific location and employed to release drugs at that site. Ultrasound cavitation, enhanced by injected microbubbles, perturbs cell membrane structures to cause sonoporation and increases the permeability to bioactive materials. Cavitation events also increase the rate of drug transport in general by augmenting the slow diffusion process with convective transport processes. Drugs and genes can be incorporated into microbubbles, which in turn can target a specific disease site using ligands such as the antibody. Drugs can be released ultrasonically from microbubbles that are sufficiently robust to circulate in the blood and retain their cargo of drugs until they enter an insonated volume of tissue. Local drug delivery ensures sufficient drug concentration at the diseased region while limiting toxicity for healthy tissues. Ultrasound-mediated gene delivery has been applied to heart, blood vessel, lung, kidney, muscle, brain, and tumour with enhanced gene transfection efficiency, which depends on the ultrasonic parameters such as acoustic pressure, pulse length, duty cycle, repetition rate, and exposure duration, as well as microbubble properties such as size, gas species, shell material, interfacial tension, and surface rigidity. Microbubble-augmented sonothrombolysis can be enhanced further by using targeting microbubbles.

Low-frequency ultrasound in biotechnology: state of the art.

The use of low-frequency (10-60 kHz) ultrasound for enhancement of various biotechnological processes has received increased attention over the last decade as a rapid and reagentless method. Recent breakthroughs in sonochemistry have made the ultrasound irradiation procedure more feasible for a broader range of applications. By varying the sonication parameters, various physical, chemical and biological effects can be achieved that can enhance the target processes in accordance with the applied conditions. However, the conditions that have provided beneficial effects of ultrasound on bioprocesses are case-specific and are therefore not widely available in the literature. This review summarizes the current state of the art in areas where sonochemistry could be successfully combined with biotechnology with the aim of enhancing the efficiency of bioprocesses, including biofuel production, bioprocess monitoring, enzyme biocatalysts, biosensors and biosludge treatment.

Ultrasound triggered image-guided drug delivery.

The integration of therapeutic interventions with diagnostic imaging has been recognized as one of the next technological developments that will have a major impact on medical treatments. Important advances in this field are based on a combination of progress in guiding and monitoring ultrasound energy, novel drug classes becoming available, the development of smart delivery vehicles, and more in depth understanding of the mechanisms of the cellular and molecular basis of diseases. Recent research demonstrates that both pressure sensitive and temperature sensitive delivery systems hold promise for local treatment. The use of ultrasound for the delivery of drugs has been demonstrated in particular the field of cardiology and oncology for a variety of therapeutics ranging from small drug molecules to biologics and nucleic acids.