Microfluidic Paper-Based Analytical Devices (μPADs) and Micro Total Analysis Systems (μTAS): Development, Applications and Future Trends

Piotr Lisowski 0 1 Pawe K. Zarzycki 0 1 0 P. Lisowski (&) P. K. Zarzycki Section of Toxicology and Bioanalytics, Koszalin University of Technology , S 1 Published in the topical collection Miniaturized and New Featured Planar Chromatography and Related Techniques with guest editor Pawe K. Zarzycki Microfluidic paper-based analytical devices and micro total analysis systems are relatively new group of analytical tools, capable of analyzing complex biochemical samples containing macromolecules, proteins, nucleic acids, toxins, cells or pathogens. Within one analytical run, fluidic manipulations like transportation, sorting, mixing or separation are available. Recently, microfluidic devices are a subject of extensive research, mostly for fast and non-expensive biochemical analysis but also for screening of medical samples and forensic diagnostics. They are used for neurotransmitter detection, cancer diagnosis and treatment, cell and tissue culture growth and amplification, drug discovery and determination, detection and identification of microorganisms. This review summarizes development history, basic fabrication methods, applications and also future development trends for production of such devices. - Over the past 20 years, there is a rapid development and increasing interest of microfluidic devices also called a micro total analysis system (lTAS), lab-on-chip (LOC) or microfluidic paper-based analytical devices (lPADs) [1, 2]. The ability to perform laboratory operations on nano- or pico-scale, using miniaturized equipment (laboratory glass, laboratory reactors) has opened new ways in modern analytical chemistry, medicine, genetic, cell biology and many other research areas. Manipulation of small volumes of fluids using channels with dimension of tens to hundred of micrometers is very appealing and has been regarded as the most powerful advantage of lab-on-chip [3]. Recently, chemists apply mini-laboratories to synthesize new molecules or materials. Biologists use them to study complex cellular processes in the extensive study of many areas of cell biology. For analytical chemists, microfluidic devices are convenient tools for detection and determination of many organic and inorganic compounds. These simple devices offer analytical and diagnostic abilities that could revolutionize medicine and pharmaceutical industry. They are small, light, portable, and have low manufacturing, usage and disposal costs. Specific to the field of microfluidics is the benefit of low consumption of reagents and analytes [4, 5]. They have been used for wide range of practical applications in many research fields: biomedical science, genomics, forensics, toxicology, immunology, environmental studies, chemistry or biochemistry. Up to this date, microfluidics were successfully used in clinical analysis of blood [69], to detect and identify pathogens, proteins [1013] and environmental contaminants [1416], in genetic research [17, 18] and drug industry [1921]. In developing countries, miniaturized portable medical diagnostic tools are especially important for the people having no direct access to medical laboratories with basic diagnostic and analytical facilities [3]. History and Development of Microfluidic Devices It is assumed that the first microfluidic device was developed in 1975 [22, 23]; however, some of them evolved from separation techniques based on thin-layer and gas chromatography. In 1938, Ukrainian scientists N.A. lzmailov and his student M.S. Shraiber published the article Spot chromatographic method of analysis and its applications in pharmacy in the journal Farmatsiya (Pharmacy) [24]. They were searching for appropriate methods for the rapid analysis of plant extracts. They coated microscope slides with a suspension of various adsorbents (calcium, magnesium, and aluminum oxide), deposited one drop of the sample solution on this layer and added one drop of the solvent. The separated sample components appeared as concentric rings that fluoresced in various colors under a UV lamp, and from that reason one of their conclusions was described as follows: A spot chromatographic method of analysis was developed; this method consists in that the separation of substances into zones is observed in thin layers of adsorbents using a drop of the substance [25]. In 1947 T.I. Williams described a further improvement of the method of Izmailov and Shraiber [26]. He prepared the adsorbent-coated glass plates in the form of a sandwich, where the adsorbent layer was covered by a second glass plate with a small hole through which the sample (and solvent) drops could be applied. For years, simplified methodology called micro planar chromatography was frequently applied for efficient separation and quantification of inorganic and organic substances [2731]. Most recently, thermostated micro-TLC protocols were successfully applied for qualitative and quantitative analysis, fractionation, screening and fingerprinting of highly organic (...truncated)