Detection of gases and organic vapors by cellulose-based sensors

The growing interest in the development of cost-effective, straightforward, and rapid analytical systems has found cellulose-based materials, including cellulose derivatives, cellulose-based gels, nanocellulosic materials, and the corresponding (nano)cellulose-based composites, to be valuable platforms for sensor development. The present work presents recent advances in the development of cellulose-based sensors for the determination of volatile analytes and derivatives of analytical relevance. In particular, strategies described in the literature for the fabrication and modification of cellulose-based substrates with responsive materials are summarized. In addition, selected contributions reported in the field of paper-based volatile sensors are discussed, with a particular emphasis on quick response (QR) code paper-based platforms, intelligent films for food freshness monitoring, and sensor arrays for volatile discrimination purposes. Furthermore, analytical strategies devised for the determination of ionic species by in situ generation of volatile derivatives in both paper-based analytical devices (PADs) and microfluidic PADs will also be described.Universidade de Vigo/CISUGAgencia Estatal de Investigación | Ref. RTI2018-093697-B-I0

Portable colorimetric sensor array technology

Humans as a species are generally audio-visual creatures and do not take full advantage of the olfactory sense. Nonetheless, even humans can recognize and differentiate among thousands of different odorants under challenging conditions. Molecular recognition by the olfactory system derives its specifity from a complex pattern of responses generated by cross-reactive olfactory receptors. These receptors are encoded by approximately one thousand genes, which represents roughly 3% of the entire human genome. As a concept, the use of multiple cross-reactive chemical sensors is broadly applicable to any situation in which the sensors can be simultaneously exposed to each of a set of multiple target analytes; such an "artificial nose" has significant potential in all areas of chemical sensor technology. The chemical sensor arrays discussed in this work are based upon cross-reactive colorimetric response: each of many sensor elements in an array is a mixture of dyes or other compounds that changes color upon exposure to an analyte. These arrays typically use strong, poorly-reversible chemical reactions involving a diverse set of color-changing dyes or chromogens; such colorimetric sensor arrays have evolved to be fast, sensitive, portable, and inexpensive. Importantly, the analyte scope of the developed arrays has been shown to be capable of tailoring based on their intended applications, and can be made to be either broad or narrow as desired: in previous works, they have proven to be capable of discriminating among a broad range of analytes including both gaseous and aqueous analytes involving many different types of chemical reactivity, including Lewis and Brønsted acidity/basicity, molecular polarity, redox properties, and chelation. Of particular interest is the study of chemicals which are hazardous to human life, by either directly interacting with the human body or indirectly causing a physical effect. This work discusses development of colorimetric sensor arrays for two such cases: aqueous toxins and explosives materials. Both types of analytes are particularly challenging due to their relative lack of chemical reactivity: aqueous toxins derive their toxicity from interaction with specific proteins within the human body, while explosives have high potential energy but are kinetically inert. Targeting these analytes while still maintaining high sensitivity, low noise, and the ability to discriminate among them was the primary focus of these two projects. Further, inexpensive portable technology for the quantitative analysis of these arrays is vitally necessary for their intended use outside of the laboratory. This work discusses development of an automated, truly portable device that fits into a pocket and improves upon previous instrumentation in scan speed, sensitivity, and noise. Since colorimetric sensor arrays are monitored by optical transduction, development of portable scanners involves investigating inexpensive, compact, low-noise optical imagers. Previous works focused on flatbed scanners, which have since shown to have limitations in portability (flatbed scanners will certainly not fit in someone's pocket), scan speed (~15-45 seconds per scan), noise (largely induced by the scanner's moving parts), and processing ability (processed manually). To improve upon this, an optical line imager known as a contact image sensor was used to act as the optical transducer; chemical sensor arrays were printed linearly so as to maintain compatibility with the line imager. The final device included disposable sensor array cartridges, a flow control system, control software, and analysis software for pattern matching

Chem Eng J

Per- and polyfluoroalkyl substances (PFAS) are a class of compounds that have become environmental contaminants of emerging concern. They are highly persistent, toxic, bioaccumulative, and ubiquitous which makes them important to detect to ensure environmental and human health. Multiple instrument-based methods exist for sensitive and selective detection of PFAS in a variety of matrices, but these methods suffer from expensive costs and the need for a laboratory and highly trained personnel. There is a big need for fast, inexpensive, robust, and portable methods to detect PFAS in the field. This would allow environmental laboratories and other agencies to perform more frequent testing to comply with regulations. In addition, the general public would benefit from a fast method to evaluate the drinking water in their homes for PFAS contamination. A PFAS sensor would provide almost real-time data on PFAS concentrations that can also provide actionable information for water quality managers and consumers around the planet. In this review, we discuss the sensors that have been developed up to this point for PFAS detection by their molecular detection mechanism as well as the goals that should be considered during sensor development. Future research needs and commercialization challenges are also highlighted.U54 OH008085/OH/NIOSH CDC HHSUnited States/U54OH008085/ACL/ACL HHSUnited States

Emerging Trends in Biogenic Amines Analysis

Biogenic amines are low-molecular-mass substances, essential for proper health for all organisms. These compounds could be detrimental to human health with various toxicological effects when they are present in high concentrations. Therefore, biogenic amines monitoring in food samples is a matter of utmost importance, and their accurate determination is considered indispensable. Under this context, we provide an overview over the most widely employed analytical techniques for biogenic amines determination such as chromatographic techniques and biosensors, emphasizing on new approaches. A critical comparison of the techniques is also given, presenting their advantages and drawbacks regarding important analytical characteristics such as sensitivity. Finally, we focus on foods in which biogenic amines mainly occur such as fish, meat and wine and other fermented products

Cellulose-Based Biosensing Platforms

Cellulose empowers measurement science and technology with a simple, low-cost, and highly transformative analytical platform. This book helps the reader to understand and build an overview of the state of the art in cellulose-based (bio)sensing, particularly in terms of the design, fabrication, and advantageous analytical performance. In addition, wearable, clinical, and environmental applications of cellulose-based (bio)sensors are reported, where novel (nano)materials, architectures, signal enhancement strategies, as well as real-time connectivity and portability play a critical role

Fluorescent-based nanosensors for selective detection of a wide range of biological macromolecules: A comprehensive review

Thanks to their unique attributes, such as good sensitivity, selectivity, high surface-to-volume ratio, and versatile optical and electronic properties, fluorescent-based bioprobes have been used to create highly sensitive nano -biosensors to detect various biological and chemical agents. These sensors are superior to other analytical instrumentation techniques like gas chromatography, high-performance liquid chromatography, and capillary electrophoresis for being biodegradable, eco-friendly, and more economical, operational, and cost-effective. Moreover, several reports have also highlighted their application in the early detection of biomarkers associ-ated with drug-induced organ damage such as liver, kidney, or lungs. In the present work, we comprehensively overviewed the electrochemical sensors that employ nanomaterials (nanoparticles/colloids or quantum dots, carbon dots, or nanoscaled metal-organic frameworks, etc.) to detect a variety of biological macromolecules based on fluorescent emission spectra. In addition, the most important mechanisms and methods to sense amino acids, protein, peptides, enzymes, carbohydrates, neurotransmitters, nucleic acids, vitamins, ions, metals, and electrolytes, blood gases, drugs (i.e., anti-inflammatory agents and antibiotics), toxins, alkaloids, antioxidants, cancer biomarkers, urinary metabolites (i.e., urea, uric acid, and creatinine), and pathogenic microorganisms were outlined and compared in terms of their selectivity and sensitivity. Altogether, the small dimensions and capability of these nanosensors for sensitive, label-free, real-time sensing of chemical, biological, and pharma-ceutical agents could be used in array-based screening and in-vitro or in-vivo diagnostics. Although fluorescent nanoprobes are widely applied in determining biological macromolecules, unfortunately, they present many challenges and limitations. Efforts must be made to minimize such limitations in utilizing such nanobiosensors with an emphasis on their commercial developments. We believe that the current review can foster the wider incorporation of nanomedicine and will be of particular interest to researchers working on fluorescence tech-nology, material chemistry, coordination polymers, and related research areas

Microfluidic paper-based analytical devices with instrument-free detection and miniaturized portable detectors

icrofluidic paper-based analytical devices (mu PADs) have attracted much attention over the past decade because they offer clinicians the ability to deliver point-of-care testing and onsite analysis. Many of the advantages of mu PADs, however, are limited to work in a laboratory setting due to the difficulties of processing data when using electronic devices in the field. This review focuses on the use of mu PADs that have the potential to work without batteries or with only small and portable devices such as smartphones, timers, or miniaturized detectors. The mu PADs that can be operated without batteries are, in general, those that allow the visual judgment of analyte concentrations via readouts that are measured in time, distance, count, or text. Conversely, a smartphone works as a camera to permit the capture and processing of an image that digitizes the color intensity produced by the reaction of an analyte with a colorimetric reagent. Miniaturized detectors for electrochemical, fluorometric, chemiluminescence, and electrochemiluminescence methods are also discussed, although some of them require the use of a laptop computer for operation and data processing

Recent advances in chemical sensors for soil analysis: a review

The continuously rising interest in chemical sensors' applications in environmental monitoring, for soil analysis in particular, is owed to the sufficient sensitivity and selectivity of these analytical devices, their low costs, their simple measurement setups, and the possibility to perform online and in-field analyses with them. In this review the recent advances in chemical sensors for soil analysis are summarized. The working principles of chemical sensors involved in soil analysis; their benefits and drawbacks; and select applications of both the single selective sensors and multisensor systems for assessments of main plant nutrition components, pollutants, and other important soil parameters (pH, moisture content, salinity, exhaled gases, etc.) of the past two decades with a focus on the last 5 years (from 2017 to 2021) are overviewed

Food for thought: optical sensor arrays and machine learning for the food and beverage industry

Arrays of cross-reactive sensors, combined with statistical or machine learning analysis of their multivariate outputs, have enabled the holistic analysis of complex samples in biomedicine, environmental science, and consumer products. Comparisons are frequently made to the mammalian nose or tongue and this perspective examines the role of sensing arrays in analyzing food and beverages for quality, veracity, and safety. I focus on optical sensor arrays as low-cost, easy-to-measure tools for use in the field, on the factory floor, or even by the consumer. Novel materials and approaches are highlighted and challenges in the research field are discussed, including sample processing/handling and access to significant sample sets to train and test arrays to tackle real issues in the industry. Finally, I examine whether the comparison of sensing arrays to noses and tongues is helpful in an industry defined by human taste