Development of new technologies for the selective removal of volatile compounds with applications in forensic science and natural aromas

Tese de doutoramento, Farmácia (Química Farmacêutica e Terapêutica), Universidade de Lisboa, Faculdade de Farmácia, 2015The increasing awareness on the environmental problems, led to an increasing demand of “greener” processes in the several fields of science, focusing mainly in solvent-free processes. We find two good examples in both forensic toxicology and natural compounds extraction fields, where solvents are still widely used. In the last twenty years hair has gained great relevance as a toxicological sample, namely in the field of drugs of abuse. Although this matrix allows the detection of such compounds after weeks, months and even years (in same cases), it requires a precleaning step (decontamination) in order to ensure the absence of drugs at the hair surface. Despite the existence of several decontamination strategies, none ensures the absence of drug at the hair surface. On the other, in the field of the extraction of natural compounds, it has been observed a rising demand for more selective, environmentally friendly, and cheaper extraction techniques that can be industrially applied. In these contexts, the non-volatility of ionic liquids (ILs) makes them almost ideal systems for the sorption of compounds. In literature it is possible to find already some applications of these liquids, namely in the adsorption of dioxins. We hereby present the development of new technologies for the selective removal of volatile compounds, applied to forensic toxicology (hair testing, using ILs) and to natural aromas (essential oils, without using ILs). We started to apply the ILs to the decontamination of hair samples containing opiates at the surface. More than forty ILs were screened (100 ºC, 96h) and the liquid 1- ethanol-3-methylimidazolium tetrafluoroborate, [C2OHMIM][BF4], showed very promising results (extraction efficiency > 80%). In order to reduce the extraction time to less than 24h, the process was optimized by means of Design of Experiment (DOE), and the final experimental conditions were 120 ºC, 16 h and a water content of 44% (w/w). The method was then compared with Cairns method (a common and very time-consuming decontamination strategy) and the results showed that the developed method yielded, in average, slightly better results (% difference ~5%). The method was then applied to both cocaine and cannabinoids. In the case of cocaine, the temperature led to the spontaneous hydrolysis of cocaine into its metabolite benzoylecgonine (BZE). Unfortunately, we were not able to remove BZE from the hair surface and no explanation for this phenomenon was found. As for the cannabinoids, the ILs screening revealed a great affinity to these compound (extraction efficiency > 90%). Once more the liquid [C2OHMIM][BF4] was chosen and the method was optimized for the cannabinoids extraction, and its final conditions were 100 ºC and 13 h. When compared with the Cairns decontamination, our method showed higher extraction efficiency. The developed decontamination procedure was then rationalized in order to fully understand the phenomenon. A three steps model was assumed: transport of the drugs to IL gas-liquid interface, adsorption onto the liquid free surface and absorption into the bulk liquid. Quartz crystal microbalance (QCM) experiments, as well as surface tension measurements were performed to evaluate the proposed model. The results confirmed that the water vapor enhances the transport of the drugs (due to solubilization). Additionally, using Kamlet-Taft parameters to characterize the polarity of ILs, we concluded that the cations with the highest acidity and lowest basicity parameters are the most efficient in the removal of the drugs from hair. The second part of the work involved the development of a new technology to selectively extract volatile compounds from botanicals. Using Eucalyptus globulus leafs as a model, a new extraction technique based on the vapor pressures was developed. In this particular case we found no need to use ILs. The method was optimized by mean of DOE and the optimum conditions were: 50 ºC, a nitrogen flow rate of 0.15 l/min , during 2.36 h. The vapor should be condensed at -10 ºC. Under these conditions the extraction yield was of 6.11 % (w/w). The method was further applied to both Lavandula dentata and Rosmarinus officinalis. The results showed not only the removal of the more volatile compounds (as expected), but also high extraction yields (7.23 % and 4.28 %, respectively).Fundação para a Ciência e a Tecnologia (FCT), SFRH/BD/73228/201

Group of Uniform Materials Based on Organic Salts (GUMBOS): A Review of Their Solid State Properties and Applications

Ionic liquids (ILs) are defined as organic salts with melting points below 100 °C. Such ionic compounds are typically formed using bulky cations and/or bulky anions in order to produce liquids or lower melting solids. ILs have been widely explored in several research areas including catalysis, remediation, solvents, separations, and many others. The utility of such compounds has also been recently broadened to include solid phase ionic materials. Thus, researchers have pushed the boundaries of ILs chemistry toward the solid state and have hypothesized that valuable properties of ILs can be preserved and fine-tuned to achieve comparable properties in the solid state. In addition, as with ILs, tunability of these solid-phase materials can be achieved through simple counterion metathesis reactions. These solid-state forms of ILs have been designated as a group of uniform materials based on organic salts (GUMBOS). In contrast to ILs, these materials have an expanded melting point range of 25 to 250 °C. In this chapter, we focus on recent developments and studies from the literature that provide for fine tuning and enhancing properties through transformation and recycling of diverse ionic compounds such as dyes, antibiotics, and others into solid state ionic materials of greater utility

Ionic Liquids and GUMBOS for Biomedical and Sensing Applications

This dissertation is a synopsis of advancements in the field of ionic liquids and a group of uniform materials based on organic salts (GUMBOS) in biomedical applications, especially with regard to cancer research. The toxicity of chemotherapeutic agents to normal tissues and drug resistance are a major concern in cancer treatment. In this dissertation, GUMBOS and nanoGUMBOS as well as ionic liquids and nanodroplets are explored as possible chemotherapeutic agents with minimal toxicity to normal cells. In the first part of my dissertation, exploitation of ionic liquid chemistry to modulate toxicity of rhodamine 6G is reported. Rhodamine 6G-based GUMBOS with varying counter-anions that are stable under physiological conditions, display excellent fluorescence photostability, and more importantly have tunable chemotherapeutic properties were synthesized. In vitro studies indicate that the hydrophobic compounds of this series allow production of nanoGUMBOS which are non-toxic to normal cells and toxic to cancer cells. Furthermore, the anions, in combination with cations such as sodium, were observed to be non-toxic to both normal and cancer cells. Thus, we demonstrate that both the cation and anion play an extremely important and cooperative role in the anticancer properties of these compounds. In the second part, the concept of multifunctional nanoparticles is introduced and exploited for theranostic applications. Nanoparticles possessing multiple properties such as luminescence, magnetism, and cancer targeting, were synthesized and explored for use in cancer therapy. In this regard, it is demonstrated that these nanoparticles can not only be used in diagnostics and as drug delivery agents, but also as active pharmacophores. Finally, the third part of this dissertation is a report of novel ionic liquid based pH sensitive colorimetric nanosensors based on phosphonium and fluorescein. The pH dependent size changes in the nanodroplets are demonstrated and potential applications in detecting acidic environment and anticancer activity are investigated

Study of dynamics and nanosegregation in ionic liquids and deep eutectic solvents by fluorescence correlation spectroscopy

Ionic liquids (ILs) and deep eutectics solvents (DESs) have emerged as a promising alternative to traditional organic solvents. This is due to their unique properties such as extremely low volatility, electroconductivity, unusual solvation and tuned miscibility, among other properties. Although, ILs and DESs are different types of solvents based on their molecular structures, they share many characteristics and properties that make them potentially attractive for a diversity of applications such as electrochemistry, synthesis, separation technologies, catalysis, materials science, and biochemistry. These unique properties have been interpreted as the result of their organization at the nanoscale level. Thus, the presence of nanosegregation in ILs and DESs is proposed to be important for many applications using these solvents, yet this nanoscale heterogeneity is poorly understood. In this dissertation, the translational diffusion dynamics of fluorophores in ILs and DESs films is reported as measured by fluorescence correlation spectroscopy. Theoretical studies have predicted a high degree of nanosegregation in tetraalkylphosphonium-based ILs. However, experimental studies that confirm these findings are scarce. To this end, fluorescence correlation spectroscopy was used to study molecular diffusion in a series of tetraalkylphosphonium ILs films. The primary motivation for this study was to understand how the nanostructural organization affects the diffusion behavior of fluorophores of different polarities, polar (Atto 590), and nonpolar fluorophore (DiD), when the cation and anion in tetraalkylphosphonium ILs are altered. From the results, it was concluded that spatial heterogeneity is present in these classes of ILs, given that the diffusion of the fluorescent probes deviates from the Brownian diffusion behavior. These deviations are attributed to the presence of structural heterogeneities in the tetraalkylphosphonium ILs. DESs have demonstrated increased potential for a diversity of applications, especially in separation technologies. Similar to ILs, nanostructural heterogeneity has been observed in DESs by theoretical and experimental studies. However, the fundamental understanding of DESs structure at the molecular level remains in a relatively early stage. To gain further insight into the presence of nanostructural heterogeneity in carboxylic-based DESs, fluorescence correlation spectroscopy experiments were performed for studying the translational diffusion properties of a hydrophilic (Atto 590) and a hydrophobic (DiI) fluorophore. Anomalous diffusion behavior was observed for the fluorescent molecules in all studied DESs. This anomalous diffusion behavior is characteristic of heterogeneous systems

DEVELOPMENT OF FUNCTIONAL NANOCOMPOSITE MATERIALS TOWARDS BIODEGRADABLE SOFT ROBOTICS AND FLEXIBLE ELECTRONICS

World population is continuously growing, as well as the influence we have on the ecosystem\u2019s natural equilibrium. Moreover, such growth is not homogeneous and it results in an overall increase of older people. Humanity\u2019s activity, growth and aging leads to many challenging issues to address: among them, there are the spread of suddenly and/or chronic diseases, malnutrition, resource pressure and environmental pollution. Research in the novel field of biodegradable soft robotics and electronics can help dealing with these issues. In fact, to face the aging of the population, it is necessary an improvement in rehabilitation technologies, physiological and continuous monitoring, as well as personalized care and therapy. Also in the agricultural sector, an accurate and efficient direct measure of the plants health conditions would be of help especially in the less-developed countries. But since living beings, such as humans and plants, are constituted by soft tissues that continuously change their size and shapes, today\u2019s traditional technologies, based on rigid materials, may not be able to provide an efficient interaction necessary to satisfy these needs: the mechanical mismatch is too prohibitive. Instead, soft robotic systems and devices can be designed to combine active functionalities with soft mechanical properties that can allow them to efficiently and safely interact with soft living tissues. Soft implantable biomedical devices, smart rehabilitation devices and compliant sensors for plants are all applications that can be achieved with soft technologies. The development of sophisticated autonomous soft systems needs the integration on a unique soft body or platform of many functionalities (such as mechanical actuation, energy harvesting, storage and delivery, sensing capabilities). A great research interest is recently arising on this topic, but yet not so many groups are focusing their efforts in the use of natural-derived and biodegradable raw materials. In fact, resource pressure and environmental pollution are becoming more and more critical problems. It should be completely avoided the use of in exhaustion, pollutant, toxic and non-degradable resources, such as lithium, petroleum derivatives, halogenated compounds and organic solvents. So-obtained biodegradable soft systems and devices could then be manufactured in high number and deployed in the environment to fulfil their duties without the need to recover them, since they can safely degrade in the environment. The aim of the current Ph.D. project is the use of natural-derived and biodegradable polymers and substances as building blocks for the development of smart composite materials that could operate as functional elements in a soft robotic system or device. Soft mechanical properties and electronic/ionic conductive properties are here combined together within smart nanocomposite materials. The use of supersonic cluster beam deposition (SCBD) technique enabled the fabrication of cluster-assembled Au electrodes that can partially penetrate into the surface of soft materials, providing an efficient solution to the challenge of coupling conductive metallic layers and soft deformable polymeric substrates. In this work, cellulose derivatives and poly(3-hydroxybutyrate) bioplastic are used as building blocks for the development of both underwater and in-air soft electromechanical actuators that are characterized and tested. A cellulosic matrix is blended with natural-derived ionic liquids to design and manufacture completely biodegradable supercapacitors, extremely interesting energy storage devices. Lastly, ultrathin Au electrodes are here deposited on biodegradable cellulose acetate sheets, in order to develop transparent flexible electronics as well as bidirectional resistive-type strain sensors. The results obtained in this work can be regarded as a preliminary study towards the realization of full natural-derived and biodegradable soft robotic and electronic systems and devices

Carbon-Based Nanomaterials for (Bio)Sensors Development

Carbon-based nanomaterials have been increasingly used in sensors and biosensors design due to their advantageous intrinsic properties, which include, but are not limited to, high electrical and thermal conductivity, chemical stability, optical properties, large specific surface, biocompatibility, and easy functionalization. The most commonly applied carbonaceous nanomaterials are carbon nanotubes (single- or multi-walled nanotubes) and graphene, but promising data have been also reported for (bio)sensors based on carbon quantum dots and nanocomposites, among others. The incorporation of carbon-based nanomaterials, independent of the detection scheme and developed platform type (optical, chemical, and biological, etc.), has a major beneficial effect on the (bio)sensor sensitivity, specificity, and overall performance. As a consequence, carbon-based nanomaterials have been promoting a revolution in the field of (bio)sensors with the development of increasingly sensitive devices. This Special Issue presents original research data and review articles that focus on (experimental or theoretical) advances, challenges, and outlooks concerning the preparation, characterization, and application of carbon-based nanomaterials for (bio)sensor development

Investigation of Volatile Organic Compounds (VOCs) released as a result of spoilage in whole broccoli, carrots, onions and potatoes with HS-SPME and GC-MS

Vegetable spoilage renders a product undesirable due to changes in sensory characteristics. The aim of this study was to investigate the change in the fingerprint of VOC composition that occur as a result of spoilage in broccoli, carrots, onions and potatoes. SPME and GC-MS techniques were used to identify and determine the relative abundance of VOC associated with both fresh and spoilt vegetables. Although a number of similar compounds were detected in varying quantities in the headspace of fresh and spoilt samples, certain compounds which were detected in the headspace of spoilt vegetables were however absent in fresh samples. Analysis of the headspace of fresh vegetables indicated the presence of a variety of alkanes, alkenes and terpenes. Among VOCs identified in the spoilt samples were dimethyl disulphide and dimethyl sulphide in broccoli; Ethyl propanoate and Butyl acetate in carrots; 1-Propanethioland 2-Hexyl-5-methyl-3(2H)-furanone in onions; and 2, 3-Butanediol in potatoes. The overall results of this study indicate the presence of VOCs that can serve as potential biomarkers for early detection of quality deterioration and in turn enhance operational and quality control decisions in the vegetable industry

Atomic spectrometry update: a review of advances in environmental analysis

This is the 33th annual review of the application of atomic spectrometry to the chemical analysis of environmental samples. This update refers to papers published approximately between August 2016 and June 2017 and continues the series of Atomic Spectrometry Updates (ASUs) in environmental analysis that should be read in conjunction with other related ASUs in the series, namely: clinical and biological materials, foods and beverages; advances in atomic spectrometry and related techniques; elemental speciation; X-ray spectrometry; and metals, chemicals and functional materials. In the field of air analysis, highlights within this review period included the fabrication of new air samplers using 3D printer technology, development of a portable aerosol concentrator unit based upon electrostatic precipitation and instrumental developments such as a prototype portable spark emission spectrometer to quantify metal particles in workplace air. The advent of ICP-MS/MS systems has enabled analysts to develop improved methods for the determination of PGEs and radioactive elements present in airborne particles. With such instruments, the capacity to eliminate or minimise many isobaric interferences now enables analysts to forego the use of many onerous sample clean-up procedures. Improvements in the capabilities of aerosol mass spectrometers were noted as were developments in other complimentary measurement techniques such as Raman. In the arena of water analysis there are growing concerns regarding engineered NPs e.g. Ag NPs, entering water courses resulting in the development and optimisation of new methods based upon FFF and sp-ICP-MS techniques to measure such inputs. Similar concerns exist for MRI contrasting agents e.g. Gd-based compounds and here improved methodologies that involve the use of sample preconcentration using chelating columns and ICP-MS analysis have been proposed. In the field of plant and soil analysis, similar to developments in the water sector, there has been increased interest in the measurement of NPs. Many comparisons of sample digestion or extraction methods have been reported but a key issue rarely addressed is transferability, i.e. whether methods preferred by one group of researchers using particular apparatus are also optimal in a different laboratory using different apparatus. New sample preconcentration methods continued to appear although – as in previous years – the CRMs selected for method validation often failed to reflect the nature of the intended sample(s). A noteworthy advance is the use of HR-CS-ETMAS for elemental analysis. Developments in LIBS included greater use of TEA CO2 lasers in place of Nd:YAG lasers and increased use of stand-off measurement. The past year has also seen a rise in proximal sensing using LIBS and pXRFS. In the field of geological analysis, the quest continues for well-characterised matrix-matched materials suitable for the calibration of elemental and, particularly, isotopic measurements by microanalytical techniques. Increasing interest in stable isotope analysis by SIMS is reflected by the number of matrix-matched RMs developed specifically for this technique. Much work continues on ways of improving isotope ratio measurements by ICP-MS and TIMS for a wide range of different isotope systems relevant to geochemical studies. High spatial resolution analysis by LIBS, LA-ICP-MS and SIMS to obtain data on chemical and isotopic variations in minerals and biogenic materials in two and three dimensions are the foundation for many new insights in geoscientific research. In XRFS and LIBS, the advantages and limitations of portable instrumentation continue to be major focus of activity

Design and engineering of microreactor and smart-scaled flow processes

This book is a reprint of the special issue that appeared in the online open access journal Processes (ISSN 2227-9717) in 2013 (available at: http://www.mdpi.com/journal/processes/special_issues/smart-scaled_flow_processes)

1-Butyl-3-Methylimidazolium Tetrafluoroborate Film as a Highly Selective Sensing Material for Non-Invasive Detection of Acetone Using a Quartz Crystal Microbalance

Breath acetone serves as a biomarker for diabetes. This article reports 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), a type of room temperature ionic liquid (RTIL), as a selective sensing material for acetone. The RTIL sensing layer was coated on a quartz crystal microbalance (QCM) for detection. The sensing mechanism is based on a decrease in viscosity and density of the [bmim][BF4] film due to the solubilization of acetone leading to a positive frequency shift in the QCM. Acetone was detected with a linear range from 7.05 to 750 ppmv. Sensitivity and limit of detection were found to be 3.49 Hz/ppmv and 5.0 ppmv, respectively. The [bmim][BF4]-modified QCM sensor demonstrated anti-interference ability to commonly found volatile organic compounds in breath, e.g., isoprene, 1,2-pentadiene, d-limonene, and dl-limonene. This technology is useful for applications in non-invasive early diabetic diagnosis