Foreword

The book has an inciting title, “Laser Optofluidics in Fighting Multiple Drug Resistance” and is dedicated to a subject of high interest that is a challenge for the biomedical specialists as well as chemists, physicists, public health experts and even outer space applicants: fighting multiple drug resistance acquired by bacteria and tumours in normal and/or extreme conditions.

The editor and the invited authors propose two action lines, each of them implying pluridisciplinary experiments and data interpretation:

1. Exposure of selected non-antibiotic medicines at UV pulsed laser beams to modify their chemical structure and generate photoproducts with enhanced properties in fighting multiple drug resistance. At the origin, the parent compounds (mainly phenothiazines, quinazolines and hydandoin derivatives) do not have significant effects on bacteria or tumour tissues, but after being exposed to laser radiation in water solutions they generate photoproducts with individual or synergistic effects on biological targets. The book shows most recent results in the action of exposed chlorpromazine and thioridazine on Gram-positive and Gram-negative bacteria and their antibacterial and antibiofilm enhanced activity. Complementary, a report about clinically used methotrexate exposed to continuous wave (UV-Vis) optical radiation emitted by lamps and then utilised on eye pseudotumours evidenced that the mixture of photoproducts has in some cases anti-inflammatory effects higher than the parent compound. Another clinically used cytostatic, 5–Fluorouracil, exposed to UV pulsed nitrogen laser beams evidenced the same effects as methotrexate.
2. The “simple” identification of the obtained photoproducts constitutes a complex problem since the photochemistry of the processes is quite complicated; consequently, many procedures are utilised with this purpose and the obtained results are described in detail in the book. One speaks about laser spectroscopy (fluorescence), mass spectrometry, thin layer chromatography, UV–Vis and FTIR absorption spectroscopy, microfluidics (surface tension, contact angles, wetting properties) measurements and many others. This is correlated with the rigorous description of microvolumetric droplets as vectors to transport medicines to targets by applying microfluidics methods and procedures. Particular attention is devoted to description of the interaction – unresonant and resonant – between a laser beam and a single droplet which is of atmost interest in biomedical applications since it allows to fast modify the content of a microdroplet and to send parts of it on the target.

In presenting results, the editor took care that the book provides more interdisciplinary and multidisciplinary information about: the laser systems used to modify pendant droplets and bulk solutions, the properties of laser beams with emphasis on those of them which are essential in reported applications, the behaviour of droplets containing medicines exposed to laser radiation in terrestrial gravity and hypergravity conditions, the micro-spectroscopy specific methods to explore droplets’ content.

The hypergravity experiments and results are groundbreaking since they show that microdroplets of chlorpromazine water solutions have better wetting properties when exposed long time to laser beams compared to water at different gravity levels. In general, unexposed/exposed medicine droplets to laser radiation have better wetting ability for cotton as well as activated charcoal target surfaces.

More, new results are shown about the way in which very small concentrations of photoproducts may be seized after exposure of compounds at laser beams, such as an antibiotic like vancomycin. The developed method is based on a microfluidic approach which allows measurement of surface tension at the interface between a gas bubble and the laser exposed solution. It may be also interpreted in terms of cleaning procedure of water from pollutants found at very low concentrations.

This E-book is very well organised in a series of condensed chapters that are illustrated with high quality figures. The text is accessible and easy to read.

The approach of the multiple drug resistance combat in the manner proposed by the editor is ground-breaking and the book opens promising perspectives in solving this threatening issue nowadays in flexible, rapid and adjustable ways.