Atomic force microscopy: A tool to study the structure, dynamics and stability of liposomal drug delivery systems

Much work has been done during the past few decades to develop effective drug delivery systems (DDS), many of which are based on nanotechnology science. Liposomes are the most attractive lipid vesicles for drug delivery. The multifunctional properties of liposomes have a key role in modifying the bioavailability profile of a therapeutic agent. Different analytical techniques can be used to describe liposomes, not least applied scanning probe microscopy (SPM) techniques. Atomic force microscopy (AFM) seems to be one of the most effectively applied SPM techniques. This review article outlines the applications of AFM in evaluating the physical characteristics and stability of liposomal DDSs. Other well-known microscopy techniques used in evaluating liposome physical characteristics are also mentioned, and the contribution of AFM to evaluating liposomal stability is discussed. Among the advantages of AFM in examining the physicochemical properties of liposomal DDSs is its ability to provide morphological and metrology information on liposome properties. AFM thus appears to be a promising tool in technological characterization of liposomal DDSs. © 2009 Informa UK Ltd All rights reserved

Theoretical study of laser-based phototherapies' improvement via upconverting nanoparticles

The introduction of new upconverting nanoparticles (UPCNPs) in the tumor area is being investigated worldwide as a solution for deep tissue theranostics interventions. Moreover, as the development of biophotonics techniques permits bioimaging in nanoscale, both photodynamic and photothermal sensing should be achieved even at cellular level with minimum perturbation, i.e., in absence of any physical contact between cells and sensing units at a single-cell level via optical tweezers. In our work, we discuss the biophotonic upconversion mechanism of nanoparticles' excitation/emission at cellular level, under laser trapping conditions, via considering laser radiation of NIR (specifically at lambda = 808 nm) for optimal penetration in biological tissues. Moreover, a theoretical simulation model will be presented for evaluation of the electric field distribution in optically trapped particles. Water soluble UPCNPs with maximum absorbance wavelength at lambda = 808 nm and emission at 545 nm and 660 nm will be studied. The photoluminescence of biocompatible UPCNPs could provide a promising powerful tool for PDT single-cell analysis and/or for photothermal enhancement and sensing in an optical tweezers' platform

Atomic force microscopy: A tool to study the structure, dynamics and stability of liposomal drug delivery systems

The value of natural additives in the food and beverage industry is estimated to increase to 45 USD billions in the global market; this figure includes vitamins, minerals and functional food ingredients according to Leatherhead’s Global Food Additives Market report, 2014. A certain growth percentage of this industry is attributed to consumer’s concerns of possible toxic effects from synthetic additives such as antioxidants, chemical preservatives and colouring agents. As an example: alternative methods to retard lipid oxidation in foods have increased the need for natural antioxidants. Sources of these natural antioxidants include the use of herbs, spices, fruits, vegetables and by-products from the food industry. It is well known that the additive and synergistic effects of the complex phytochemical mix present in these 296plant sources are responsible for their enhanced antioxidant activity (Neacsu et al., 2015). Recent publications (Konczak et al., 2009, 2010b; Sakulnarmrat and Konczak, 2012) have reported about the high antioxidant capacities of commercially grown Australian native plant foods which are far greater than those previously reported for blue berries, well known for its high antioxidant levels. The enhanced antioxidant capacity of native plant foods such as Kakadu plum is mainly attributed to the high levels of vitamin C and phenolic compounds (Konczak et al., 2009)

Non-ionizing, laser radiation in Theranostics: The need for dosimetry and the role of Medical Physics

The discovery of coherent laser light in 1960 shifted and expanded the biomedical applications of radiation to the non-ionizing part of the electromagnetic spectrum. As in the case of ionizing radiation, but considering the laser specific features, the effective, safe and ethically acceptable use of biomedical laser technology requires interdisciplinary collaboration between physicists, engineers and physicians. This should extend at the research, preclinical and clinical level, inspiring at this time the dynamic discipline of Medical Physics in new areas. With this work we aim to introduce the interested reader in the need of dosimetry in medical applications of laser radiation, as this field is still unexplored. After some necessary definitions, we give a brief review of the basic biophysical mechanisms of coherent light-matter interactions. The manuscript focuses on biomedical laser applications in diagnosis and therapy (i.e. in Theranostics). From the vast field of laser theranostic applications we have chosen some experimental and theoretical results – examples of quantification of the laser effect, particularly relevant to soft and hard tissue laser ablation, laser induced photodiagnosis and photodynamic therapy of cancer. These topics intend to highlight the important role of Medical Physicists in the optimization of well-established laser based clinical procedures and mainly emerge the necessity of the relevant dosimetry for each application. Finally, we hope that this effort is going to give food for thought and highlight the importance of deep knowledge of the physics behind some everyday medical applications. © 2019 Associazione Italiana di Fisica Medic