Optical multiple chemical sensing: status and current challenges

Multiple optical sensors for chemical species are sensitive, non-toxic and non-invasive and enable spatially and temporally resolved multianalyte detection. Recent advances are highlighted with a focus on fluorescence-based methods and the biologically and clinically important analytes oxygen, pH, carbon dioxide and temperature. Indicator chemistries such as permeation-selective microbeads and nanoparticles allow the production of microscopically homogeneous sensor layers. The use of combinations of spectral discrimations along with time-resolved monitoring schemes based on luminescence lifetime or intensity-lifetime ratios enables all-optical real-time multianalyte determination.     

A perspective on single molecule SERS: current status and future challenges

We present an overview of a some of the basic principles underlying current research in single-molecule surface-enhanced Raman scattering (SM-SERS). We summarize, by the same token, a series of conditions and characteristics that are common to most SM-SERS conditions, and discuss their implications for the understanding of data and for the comparison among different methods. We try to emphasize aspects of the problem that are not conventionally discussed in detail in the literature. In particular, we provide a full length discussion on the topics of: (i) the minimum SERS enhancement necessary to observe a single molecule, and (ii) the spatial distribution of the enhancement factor (EF) around hot-spots (which affects the statistics of SM-SERS events). A brief outlook into future perspectives of the different techniques used in SM-SERS and a few outstanding questions are also provided.     

Advances in pesticide biosensors: current status, challenges, and future perspectives

Public concern over pesticide residues has been increasing dramatically owing to the high toxicity and bioaccumulation effects of pesticides and the serious risks that they pose to the environment and human health. It is therefore crucial to monitor pesticide residues by using various analytical methods and techniques, especially highly sensitive, highly selective, simple, rapid, cost-effective, and portable ones. Biosensor strategies have become research hotspots and ideal candidates for pesticide detection, having such features as high sensitivity, fast response, robustness, low cost and miniaturization, as well as in situ and real-time monitoring. This review covers advances in the design and fabrication of biosensors for pesticide detection since 2005. Special emphasis is placed on the state-of-art selection of receptors, the use of different transduction techniques and fast screening strategies, and the application of various biosensors developed in food and environmental safety. Both advantages and drawbacks of these techniques are then summarized. Finally, challenges, strategies, and perspectives in further developing pesticide biosensors are also discussed.

Method validation in analytical sciences: discussions on current practice and future challenges

Accreditation and Quality Assurance - Eurachem held a workshop on method validation in analytical sciences in Gent, Belgium, on 9–10 May 2016. A summary of the working group discussions is...     

Chemical accuracy in ab initio thermochemistry and spectroscopy: current strategies and future challenges

The current state of the art in wavefunction-based electronic structure methods is illustrated via discussions of the most important effects incorporated into a selection of high-accuracy methods chosen from the chemical literature. If one starts with a high-quality correlation treatment, such as provided by the CCSD(T) coupled cluster method, the leading effects include convergence of the results with respect to the 1-particle basis set, (outer)core/valence correlation, scalar relativistic effects and a number of smaller effects. For thermochemical properties such as the heat of formation, the zero-point vibrational energy also becomes important, introducing its own set of difficulties to the computational approach. Changes in the various components as the chemical systems incorporate heavier elements and as the size of the systems grows are also considered. Finally, challenges arising from the desire to extend existing methods to transition metal and heavier elements are considered.     

Metalloprotein and metallo-DNA/RNAzyme design: current approaches, success measures, and future challenges

Specific metal-binding sites have been found in not only proteins but also DNA and RNA molecules. Together these metalloenzymes consist of a major portion of the enzyme family and can catalyze some of the most difficult biological reactions. Designing these metalloenzymes can be both challenging and rewarding because it can provide deeper insights into the structure and function of proteins and cheaper and more stable alternatives for biochemical and biotechnological applications. Toward this goal, both rational and combinatorial approaches have been used. The rational approach is good for designing metalloenzymes that are well characterized, such as heme proteins, while the combinatorial approach is better at designing those whose structures are poorly understood, such as metallo-DNA/RNAzymes. Among the rational approaches, de novo design is at its best when metal-binding sites reside in a scaffold whose structure has been designed de novo (e.g., alpha-helical bundles). Otherwise, design using native scaffolds can be equally effective, allowing more choices of scaffolds whose structural stability is often more resistant to multiple mutations. In addition, computational and empirical designs have both enjoyed successes. Because of the limitation in defining structural parameters for metal-binding sites, a computational approach is restricted to mostly metal-binding sites that are well defined, such as mono- or homonuclear centers. An empirical approach, even though it is less restrictive in the metal-binding sites to be designed, depends heavily on one's knowledge and choice of templates and targets. An emerging approach is a combination of both computational and empirical approaches. The success of these approaches can be measured not only by three-dimensional structural comparison between the designed and target enzymes but also by the total amount of insight obtained from the design process and studies of the designed enzymes. One of the biggest advantages of designed metalloenzymes is the potential of placing two different metal-binding sites in the same protein framework for comparison. A final measure of success is how one can utilize the insight gained from the intellectual exercise to design new metalloenzymes, including those with unprecedented structures and functions. Future challenges include designing more complex metalloenzymes such as heteronuclear metal centers with strong nanomolar or better affinities. A key to meeting this challenge is to focus on the design of not only primary but also secondary coordination spheres using a combination of improved computer programs, experimental design, and high-resolution crystallography.     

Quality control techniques for chemical analysis: some current shortcomings and possible future developments

Current approaches to quality control in chemical analysis are examined. Issues that frequently cause problems are proposed. Future developments relating to ways in which the incidence of mistakes might be reduced are discussed as possible supplements to more well-established quality control measures.     

Biological entities as chemical reactors for synthesis of nanomaterials: Progress,challenges and future perspective

Synthesis of nanomaterials is being gained extensive attention in the fields of chemistry, applied physics, catalysis, drug delivery and the most important in diagnosis and therapeutic applications. Recently, many reports have been published on physical and chemical synthesis of magnetic as well as metallic nanoparticles (NPs) with viable surface functionalization, but still there is a dire need of such strategies that can combine synthetic methodology with stable surface modification found in nature. Synthesis of NPs via biological methods is the possible way to solve these barriers. However, systematized summary and outlooks of NPs synthesis via biological entities with various influencing factors e.g. temperature, pH, concentration of reactants and reaction time has rarely been reported. This review will present the distinct advantages of biological synthesis of NPs over physical and chemical methods. It will also highlight the recent progress on synthesis of NPs via various biological systems i.e. plant, fungus, bacteria, and yeast. Furthermore, it will explain various factors that control the size, shape, and morphology of these NPs. Finally, it would present the future perspectives of green chemistry for the development of nano-science and -biotechnology.     

Electronic structure theory: present and future challenges

The aim of electronic structure theory is to solve the electronic Schrödinger equation, which is a coupled high-dimensional partial differential equation with numerous singularities in the operator and complex boundary conditions arising from the fermion symmetry. This article briefly summarizes how electronic structure theorists have overcome the immense difficulties of solving this with quantitative accuracy. This has been achieved by elucidating the structure of wave functions and exploiting this knowledge to drastically expedite the numerical solutions, enabling predictive simulations for a broad range of chemical properties and transformations. It also lists some of the outstanding challenges that are to be or being addressed.     

Singlet oxygen luminescence dosimetry (SOLD) for photodynamic therapy: current status, challenges and future prospects

As photodynamic therapy (PDT) continues to develop and find new clinical indications, robust individualized dosimetry is warranted to achieve effective treatments. We posit that the most direct PDT dosimetry is achieved by monitoring singlet oxygen (1O2), the major cytotoxic species generated photochemically during PDT. Its detection and quantification during PDT have been long-term goals for PDT dosimetry and the development of techniques for this, based on detection of its near-infrared luminescence emission (1270 nm), is at a noteworthy stage of development. We begin by discussing the theory behind singlet-oxygen luminescence dosimetry (SOLD) and the seminal contributions that have brought SOLD to its current status. Subsequently, technology developments that could potentially improve SOLD are discussed, together with future areas of research, as well as the potential limitations of this method. We conclude by examining the major thrusts for future SOLD applications: as a tool for quantitative photobiological studies, a point of reference to evaluate other PDT dosimetry techniques, the optimal means to evaluate new photosensitizers and delivery methods and, potentially, a direct and robust clinical dosimetry system.     

Merging structural biology with chemical biology: Structural Chemistry at Eskitis

This review introduces the Structural Chemistry Program at Griffith University’s Eskitis Institute, and provides a brief overview over its current and future research portfolio. Capitalising on the co-location with the Queensland Compound Library (QCL), Australia’s only small molecule repository, our laboratory investigates the structure and function of proteins with the aim of learning about their molecular mechanisms. Consequently, these studies also feed into drug discovery and design. The thematic focus of our Program is on proteins involved in infection, inflammation and neurological diseases, and this review highlights a few of our recent research efforts in this area.

     

Bioanalysis in single cells: current advances and challenges

Cells, basic units of living structures and functions, build up a complicated small world, and their order and complexity resemble a small universe. The detailed understanding and elucidation of the matter transport and energy conversion mechanisms within a single cell will expand our knowledge about the origin and evolution of life, the disease mechanisms and much more. In past decades, single-cell analysis has been rapidly and significantly improved and various methodologies have been developed to reveal the complexity of mass, energy, and information within single cells. In this review, we focused on the methods developed in recent years for single-cell analysis, including electrochemical method, optical method, and mass spectrometry method. We reviewed the recent advances and representative studies in this research field, and also discussed the strengths and limitations of each method. Finally, we presented the existing technical challenges and further directions for single-cell analysis.     

Lessons from the past and charting the future of marine natural products drug discovery and chemical biology

Marine life forms are an important source of structurally diverse and biologically active secondary metabolites, several of which have inspired the development of new classes of therapeutic agents. These success stories have had to overcome difficulties inherent to natural products-derived drugs, such as adequate sourcing of the agent and issues related to structural complexity. Nevertheless, several marine-derived agents are now approved, most as "first-in-class" drugs, with five of seven appearing in the past few years. Additionally, there is a rich pipeline of clinical and preclinical marine compounds to suggest their continued application in human medicine. Understanding of how these agents are biosynthetically assembled has accelerated in recent years, especially through interdisciplinary approaches, and innovative manipulations and re-engineering of some of these gene clusters are yielding novel agents of enhanced pharmaceutical properties compared with the natural product.     

Rice proteomics: current status and future perspectives

Rice, the first cereal crop genome to be decoded, has attracted the attention of researchers worldwide because of its immense socio-economic impact on human existence. With the availability of the draft genome sequence of two major types, japonica- and indica-rice, "rice proteomics" has entered into the era of functional genomics. Although during the last decade an important but limited progress (mainly construction of protein datafiles) has been made in the field of rice proteomics, it is only recently that dedicated research groups have taken this challenge to systematically analyze the rice proteome at the cell (and organelle), tissue, and whole plant level. Important gains achieved by the accelerated technological progress in protein separation and identification will help in going beyond the simple cataloguing of rice proteins in realistic terms. In this review, we discuss the progress made in the field of rice proteomics to date and dwell upon the future direction/problems/approaches towards defining the rice proteome.     

Micellar electrokinetic chromatography: current developments and future

This review highlights recent methodological and instrumental advances in micellar electrokinetic chromatography (MEKC). Enhancements in sensitivity and selectivity of the technique through the use of on-line preconcentration approaches (stacking and sweeping) and nonconventional pseudostationary phases, namely nonionic and zwitterionic surfactants, mixed micelles and polymers, are discussed in detail. Laser-induced fluorescence and mass spectrometry, as alternatives to UV-absorption detection, have been covered to evaluate their advantages and limitations when applied to analysis in an MEKC format. Some thoughts on future directions in this area such as in-capillary reactions, coated capillaries and MEKC on microchips are also presented.     

RNA-based therapeutics: current progress and future prospects

Recent advances of biological drugs have broadened the scope of therapeutic targets for a variety of human diseases. This holds true for dozens of RNA-based therapeutics currently under clinical investigation for diseases ranging from genetic disorders to HIV infection to various cancers. These emerging drugs, which include therapeutic ribozymes, aptamers, and small interfering RNAs (siRNAs), demonstrate the unprecedented versatility of RNA. However, RNA is inherently unstable, potentially immunogenic, and typically requires a delivery vehicle for efficient transport to the targeted cells. These issues have hindered the clinical progress of some RNA-based drugs and have contributed to mixed results in clinical testing. Nevertheless, promising results from recent clinical trials suggest that these barriers may be overcome with improved synthetic delivery carriers and chemical modifications of the RNA therapeutics. This review focuses on the clinical results of siRNA, RNA aptamer, and ribozyme therapeutics and the prospects for future successes.     

Ice chromatography: current progress and future developments

Ice chromatography, in which water-ice particles are employed as a chromatographic stationary phase, has proven an efficient technique for probing the solution/ice interface. The preparation of fine ice particles has allowed us to not only obtain higher-resolution separation but also investigate the molecular processes occurring on the ice surface in more detail. Chromatographic investigations have revealed that two or more hydrogen bonds are simultaneously formed between a solute and the dangling bonds on the ice surface when the solute gives measurable retention. Several compounds, including estrogens, amino acids, and acyclic polyethers, have been successfully separated by ice chromatography with a hexane-based mobile phase. In addition, this method effectively probes the surface melting of the ice stationary phase and the liquid phase that coexists with water ice at thermodynamic equilibrium. The thickness of the surface liquid layer and the size of the liquid phase that grows inside an ice particle have been evaluated. The perspectives of this method are also discussed.      

Analytical microextraction: current status and future trends

Analytical microextractions, defined as nonexhaustive sample preparation with a very small volume of extracting phase (microliter range or smaller) relative to the sample volume, represent an important development in the field of analytical chemistry. Analytes are extracted by a small volume of a solid or semi-solid polymeric material, as in solid-phase microextraction (SPME), or alternatively by a small volume of a liquid, as in liquid-phase microextraction (LPME). This paper gives an overview of the SPME and LPME techniques and discusses future trends. This includes a discussion of the different extraction formats available, commercial equipment, method transfer from traditional sample preparation methods to microextraction, and performance as well as robustness for the latter type of systems. In addition, the paper contains a unified approach to the understanding of extraction thermodynamics and kinetics applicable to both SPME and LPME.     

Official proficiency tests of the organisation for the prohibition of chemical weapons: current status and future directions

The Organisation for the Prohibition of Chemical Weapons (OPCW) has been organising and conducting Official Proficiency Tests (PT) since 1996 in accordance with ILAC-G13 to certify laboratories for the analysis of authentic samples under the provision of Chemical Weapons Convention. The tests are part of a mechanism to ensure that there are laboratories that have proven competence in the analysis of chemicals related to the Convention. Laboratories that have successfully completed the tests are designated by the Director General of the OPCW for analysis of authentic samples. To maintain the Designated Laboratory status, a laboratory must take and pass at least one of the two proficiency tests offered per calendar year. Unlike many proficiency tests, the OPCW PT is qualitative, that is the laboratories must determine if any of a very large set (essentially infinite) of chemicals relevant to the Convention are present in the samples. The tests are organised with the assistance of two laboratories, one preparing the test samples, and the other evaluating the test results. The paper provides an overview of the current status of these PTs and outlines salient features regarding procedure and scope of tests, selection of assisting laboratories, scoring and performance rating of participating labs. The emerging issues are also briefly discussed.