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In this work, we utilise the disulphide bond structure of insulin and a new benzothiazole Raman probe for the detection of human insulin using surface-enhanced Raman spectroscopy (SERS). The disulphide bond structure of the insulin was reduced to generate free sulfhydryl terminal groups. When reacted with benzothiazole-functionalised gold nanoparticles, the reduced protein desorbs the Raman probe and causes its Raman signal intensity to quench. Using this approach, insulin was quantified in the concentration range of 1 × 10-14 -1 × 10-8 M by SERS quenching. The limit of quantification of insulin by the SERS quenching method was found to be 1 × 10-14 M (0.01 pM or 58 pg/L), which satisfies the requirements for monitoring its blood concentration in patients. Because many proteins and peptides have disulphide bonds in their molecular structures, the new SERS quenching method has a strong potential for the rapid determination of ultralow concentrations of proteins in formulations and biological fluids.

In recent years, conducting polymers are playing a significant role in the field of display devices, transistors, solar cells, sensors, and electrochromic windows due to their outstanding optoelectronic and semiconducting properties due to their conjugated backbone. One potential application that is not as widely explored using these materials is biosensing, where advantage is taken of the porosity that can be generated by the polymerization of a three-dimensional network. There are various approaches for producing conjugated microporous polymers using trifunctional or multifunctional monomers synthesized via chemical or electrochemical methods. In this work, we have used electropolymerization to synthesize conjugated polymer films on a working electrode of flexible indium tin oxide (FITO) using a trifunctional conjugated monomer 1,3,5-tri(furan-2-yl)benzene (TFB). There are several parameters that influence the formation of a porous polymer film, and the most critical ones are substrate conductivity, roughness, method of electropolymerization, and choice of an electrolyte. These porous electropolymerized films were characterized using UV–vis spectroscopy (UV–vis), X-ray photoelectron spectroscopy (XPS), surface profilometry, four-point probe conductivity measurements, and scanning electron microscopy (SEM). The polymer films that were electropolymerized using chronoamperometry rather than repetitive potential cycling demonstrated a more suitable morphology to trap DNA/RNA analytes for biosensing applications.

2D black phosphorus (BP) is one promising electrocatalyst toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalysis. The too strong adsorption of oxygen intermediates during OER, while the too weak adsorption of hydrogen intermediate during HER, however, greatly compromise its practical water splitting applications with overpotentials as high as 450 mV for OER and 420 mV for HER to achieve 10 mA cm-2 under alkaline conditions. Herein, by rationally introducing the nanosized iridium (Ir) modifier together with optimized exposing surface toward electrolytes, an efficient Ir-modified BP electrocatalyst with much favorable adsorption energies toward catalytic intermediates possesses an outstanding pH-universal water splitting performance, surpassing the nearly all reported BP-based catalysts and the commercial noble-metal catalysts. The Ir-modified BP catalyst with the optimized exposed surfaces only requires an overall cell voltage of 1.54 and 1.57 V to achieve 10 mA cm-2 in acidic and alkaline electrolysers, respectively. This design uncovers the potential applications of 2D BP in practical electrocatalysis fields via decreasing reaction intermediate adsorption energy barriers and promoting the interfacial electron coupling for heterostructured catalysts, and offers new insights into the surface-dependent activity enhancement mechanism.

Cardiac troponin I (cTnI) is a sensitive biomarker for cardiovascular disease (CVD). Rapid determination of cTnI concentration in blood can greatly reduce the potential of significant heart damage and heart failure. Herein, we demonstrate a new electrochemical immunosensor for selective affinity binding and rapid detection of cTnI in blood plasma by an electrochemical method. A conductive film of “poly 2,5-bis(2-thienyl)3,4-diamine-terthiophene (PDATT)” was deposited onto an Indium Tin Oxide (ITO) electrode using chronoamperometry. Anti-cardiac troponin I antibody was then attached to the two amine (NH2) groups substituted on the central thiophene of terthiophene repeating unit of the polymer chain via amide bond formation. The gaps on the surface of the antibody coated immunosensor were backfilled with bovine serum albumin (BSA) to prevent nonspecific binding of interfering molecules. Differential pulse voltammetry (DPV) was used to determine cTnI upon the formation of cTnI immunocomplex on the sensing surface, appearing a peak at 0.27 V. The response range was 0.01–100 ng mL−1 with limit of quantification down to 0.01 ng mL−1. The developed immunosensor was used to determine cTnI in spiked blood plasma without interference from cardiac troponin T (cTnT). Therefore, this new sensor can be utilised for the detection of cTnI biomarker in pathological laboratories and points of care in less than 15 min.

Two-dimensional (2D) bismuth oxide (Bi2O3) heterostructured nanosheets (BOHNs) were first fabricated by a solution-based molecular self-assembly approach. The synthesized BOHNs nanosheets feature mixed α- and β-phases and rich surface/edge-active sites. When utilized as anode materials for rechargeable batteries, dual-phase BOHNs deliver an initial discharge capacity as high as 647.6 mAh g-1 and an increased capacity of over 200 mAh g-1 remained after 260 cycles for lithium-ion batteries (LIBs), and a stable cycling capacity at ∼50 mAh g-1 after 500 cycles for sodium-ion batteries (SIBs). A novel flexible 2D/1D/2D structure is further developed by implanting 2D BOHNs into conductive 1D carbon nanotubes and 2D graphene to form composite (BOHNCG) paper as free-standing anodes for both LIBs and SIBs. The capacity of 2D/1D/2D BOHNCG as a LIB anode reaches 823.5 mAh g-1, corresponding to an enhancement of ∼27%, and remains at >110 mAh g-1 after 80 cycles as a SIB anode with greatly improved cycling stability. This work verifies the promising potential of 2D BOHNs for practical energy-related devices and enriches the current research on emerging 2D nanomaterials.

Product selectivity of alkyne hydroamination over catalytic Au2Co alloy nanoparticles (NPs) can be made switchable by a light-on/light-off process, yielding imine (cross-coupling product of aniline and alkyne) under visible-light irradiation, but 1,4-diphenylbutadiyne in the dark. The low-flux light irradiation concentrates aniline on the catalyst, accelerating the catalytic cross-coupling by several orders of magnitude even at a very low overall aniline concentrations (1.0×10−3 mol L−1). A tentative mechanism is that Au2Co NPs absorb light, generating an intense fringing electromagnetic field and hot electrons. The sharp field-gradient (plasmonic optical force) can selectively enhance adsorption of light-polarizable aniline molecules on the catalyst. The light irradiation thereby alters the aniline/alkyne ratio at the NPs surface, switching product selectivity. This represents a new paradigm to modify a catalysis process by light.

A novel 2D-TiO2-2D van der Waals (vdW) heterostructured (BPNs@TiO2@G) hydrogel is developed as a high-performance anode material for lithium ion batteries by coating black phosphorus nanosheets (BPNs) onto porous graphene/TiO2 composite hydrogel (TiO2@G). This unique 2D-TiO2-2D vdW heterostructure not only prevents close restack between 2D nanosheets, but also provides rapid interlayer transfer paths and enhanced interfacial storage, together with some inherited advantages from 2D BPNs and graphene, such as shortened diffusion pathways, improved conductivity, supressed volume changes and lithium dendrite growth over cycling. As a result, BPNs@TiO2@G anode delivers an attractive initial discharge capacity as high as 1336.1 mAh g−1 (at 0.2 A g−1), a superior rate capability (271.1 mAh g−1 at 5.0 A g−1), and a good cycling life (502 mAh g−1 for 180 cycles) under a potential window close to 3.0 V. This study thus opens a new window for designing novel high-performance electrodes for electrochemical energy storage devices.

Due to its high analytical sensitivity and field deplorability, surface enhanced Raman spectroscopy (SERS) has emerged as an analytical tool for detecting environmental toxicants in different matrices. Progress has been made towards development of methods for depositing nanostructures onto solid platforms to design SERS substrates. The properties of the solid platforms used for SERS substrates fabrications such as electrical and heat conductivity, malleability and foldability, have significant influence on then design of the nanostructures and are critical for SERS technique. This review takes a look at recent advances in commonly employed conductive solid materials such as indium tin oxide, carbon fiber, silicon wafers, polyaniline fiber and carbon nanotubes as the supporting platforms for fabricating SERS substrates. It also examines their influence on the fabrication method, the morphology of the nanostructures formed as well as the hot spot density on the resultant novel SERS substrates. Real world applications of these substrates for the detection of environmental toxicants over the past decade have been shown. The review indicates that while significant advances have been made on the use of the conductive properties of these support platforms for SERS substrate fabrication, their subsequent application to detect environmental toxicants have not been fully explored.

Diketopyrrolopyrrole (DPP) is one of the most fascinating organic dyes, and has gained significant attention in the organic electronic community in recent times. Due to their outstanding semiconducting properties, DPP-based small molecules and polymers can be used as active semiconductor thin films for various high performance electronic devices. However, although several flanking groups attached to the DPP backbone have been reported in the literature for DPP molecules, there is little study about the effect of fused rings flanked on both sides of the DPP core. Recently our group reported for the first time a naphthalene-flanked DPP as a new DPP family member. In this work, we have performed electropolymerization studies on a newly synthesized naphthalene flanked DPP core with two alkyl chains, hexyl (H-DPPN) and octyl (O-DPPN), as conjugated monomers. Electrochemical studies have been carried out on glassy carbon (GC) and indium tin oxide (ITO) electrodes by using repetitive cyclic voltammetry (CV) as the deposition technique for up to 50 cycles. The concentration of H-DPPN and O-DPPN solution in dichloromethane was found to be a key parameter when optimizing conditions for obtaining an electropolymerised thin film, although other parameters such as the electrolyte, potential range, number of cycles, and the nature of the electrode all play a role in successful thin film formation. The electropolymerized thin films were characterised using UV-Vis spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photon spectroscopy (XPS) and surface profilometry. We found that each monomer produced different film morphologies on glassy carbon and ITO electrodes. We believe that electropolymerized poly(H-DPPN) and poly(O-DPPN) thin film electrodes could be used for various applications such as studying redox reactions and bio-sensing.

Limited knowledge of the combined effects of water and sediment properties and metal ionic characteristics on the solid-liquid partitioning of heavy metals constrains the effective management of urban waterways. This study investigated the synergistic influence of key water, sediment and ionic properties on the adsorption-desorption behavior of weakly-bound heavy metals. Field study results indicated that clay minerals are unlikely to adsorb heavy metals in the weakly-bound fraction of sediments (e.g., r = −0.37, kaolinite vs. Cd), whilst dissociation of metal-phosphates can increase metal solubility (e.g., r = 0.61, dissolved phosphorus vs. Zn). High salinity favors solubility of weakly-bound metals due to cation exchange (e.g., r = 0.60, conductivity vs. Cr). Dissolved organic matter does not favor metal solubility (e.g., r = −0.002, DOC vs. Pb) due to salt-induced flocculation. Laboratory study revealed that water pH and salinity dictate metal partitioning due to ionic properties of Ca2+ and H+. Selectivity for particulate phase increased in the order Cu>Pb>Ni>Zn, generally following the softness (2.89, 3.58, 2.82, 2.34, respectively) of the metal ions. Desorption followed the order Ni>Zn>Pb>Cu, which was attributed to decreased hydrolysis constant (pK1 = 9.4, 9.6, 7.8, 7.5, respectively). The study outcomes provide fundamental knowledge for understanding the mobility and potential ecotoxicological impacts of heavy metals in aquatic ecosystems.

Background Dewatering constitutes a major challenge to the production of microalgae, accounting for 20–30% of the product cost. This presents a setback for the applicability of microalgae in the development of several sustainable products. This study presents an investigation into the dynamic dewatering of microalgae in a combined flocculation-filtration process. The effect of process conditions on the performance of 12 flocculants and their mixtures was assessed. Results The mechanism of flocculation via the electrostatic path was dominated by charge neutralization and subsequently followed bridging in a ‘sweep flocculation’ process. Cationic polyacrylamide (CPAM) based flocculants recorded the highest biomass retention with PAM1 and PAM2 attaining 99 and 98% retention with flocculant dosages of 10 and 15 mg/L respectively. Polyvinylamine (PVAM) was also found to improve system stability across the pH range 4–10. Alum was observed to be only effective in charge neutralization, bringing the system close to its isoelectric point (IEP). Chemometric analysis using the multi-criteria decision methods, PROMETHEE and GAIA, was applied to provide a sequential performance ranking based on the net outranking flow (ф) from 207 observations. A graphical exploration of the flocculant performance pattern, grouping the observations into clusters in relation to the decision axis ($$\pi$$ π ), which indicated the weighted resultant of most favorable performance for all criteria was explored. Conclusion CPAM based flocculants and their mixtures demonstrated superior performance due to their viscoelastic behaviour under turbulence. The use of PVAM or alum in mixtures with CPAM reduced the required doses of both flocculants, which will provide beneficial financial impact for largescale microalgae dewatering in a flocculant assisted dynamic filtration process. Chemometric analysis based on the physico-chemical properties of the system provides a time saving assessment of performance across several criteria. The study findings provide an important foundation for flocculant assisted dynamic filtration processes.

Bioavailability is a critical facet of metal toxicity. Although past studies have investigated the individual role of sediment physico-chemical properties in relation to the bioavailability of heavy metals, their collective effects are little-known. Further, limited knowledge exists on the contribution of nutrients to metal bioavailability. In this study, the influence of physico-chemical properties of sediments, including total organic carbon (TOC), total phosphorus (TP), total nitrogen (TN), cation exchange capacity (CEC), specific surface area (SSA), and mineralogical composition to metal bioavailability is reported. The weak-acid extraction method was used to measure Cd, Cr, Cu, Ni, Pb and Zn as the potentially bioavailable fraction in sediments in an urban creek. The results confirmed that Cu has strong selectivity for organic matter (r = 0.814, p

Recombinant human erythropoietin (rHuEPO) is an important hormone drug that is used to treat several medical conditions. It is also frequently abused by athletes as a performance enhancing agent at sporting events. The time window of the rHuEPO in blood is short. Therefore, the rapid detection of rHuEPO use/abuse at points of care and in sports requires a selective analytical method and a sensitive sensor. Herein, we present a highly selective method for the rapid detection of rHuEPO in human blood plasma by a sensitive optical sensor. rHuEPO is selectively extracted from human blood plasma by a target-specific extractor chip and converted into a biothiol by reducing its disulfide bond structure. The formed biothiol reacts with a water soluble (E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diolHg(ii) (BAN-Hg) optical sensor and causes its rapid decomposition. This leads to a rapid change in the sensor color from blue to pink that can be observed by the naked eye. The optical sensor was used to quantify rHuEPO in the concentration range 1 × 10-8 M to 1 × 10-12 M by UV-Vis spectroscopy. For the screening of blood plasma, an EPO-specific extractor chip was synthesized and used to selectively extract the protein from the biological matrix prior to its conversion into biothiol and quantification by the optical sensor. Since many proteins have a disulfide bond structure, the new method has strong potential for their rapid sensitive and selective detection by the BAN-Hg sensor and UV-Vis spectroscopy.

Heteroatom-doping engineering has been verified as an effective strategy to tailor the electronic and chemical properties of materials. The high amount doping of nonmetal atoms to achieve desired performance, however, is always a grand challenge. Herein, a new strategy to achieve ultrahigh-level doping of phosphorus in a 3D graphene skeleton is proposed by sacrificing heterostructured two-dimensional black phosphorus on graphene. Via this approach, the phosphorus-loading in graphene hydrogel reached a record of 4.84 at. %, together with the formation of tunable pores of size 1.7–17.5 nm in graphene. During reaction kinetic analysis, the highly phosphorus-doped 3D graphene hydrogel anode exhibited more favorable capacitive-controlled ion storage behaviors, leading to a specific capacity as high as 1000 mA h g–1 after 1700 cycles, which is superior to the pristine graphene hydrogel electrode. This simple but effective phosphorization offers an effective doping strategy for producing ultrahigh-level phosphorous doping but avoids the usual use of toxic phosphorous precursors. Furthermore, the modulation on the activation process over cycling investigated in this work gives us a new insight into designing stable anodes for carbonaceous electrode materials.

Road dust is a key repository for PAHs and transformed PAH products (TPPs) generated from natural and anthropogenic sources in the urban environment. Eventhough PAHs and TPPs are prone to post-emission photochemical processes, very limited studies exist on the subject for road dust. This knowledge gap is of particular concern since some of the resultant TPPs are notably more carcinogenic than their precursor PAHs. This study evaluated the role of 254 nm ultraviolet (UV) photons on the photochemistry of PAHs and TPPs in road dust. The findings show that UV irradiation had varying effects on the fate of analytes, particularly naphthalene (NAP), phenanthrene (PHE), 7, 12-dimethylbenz(a)anthracene (DMBA), 1-hydroxypyrene (HPY), 1-nitropyrene (1NPY), pyrene (PYR) and 5-nitroacenaphthene (5NAC). Photochemical relationship was identified between PYR, 1NPY and HPY, and DMBA and benzo(a)anthracene. Unlike carbonyl-PAHs, parent PAHs, nitro-PAHs and hydroxy-PAHs can originate from photolysis. Photon irradiation durations of 3, 6 and 7.5 h had the most intense influence on the photolytic process with 7.5 h as optimum. The photochemical rate at optimum irradiation duration shows an increasing trend of NAP PHE1NPY DMBA5NAC HPY with respective estimates of 0.08, 0.11, 0.21, 0.22, 0.43, and 0.59 mg kg

The development, modification and optimization of analytical methods capable of simultaneous extraction and in-cell clean-up of extracts for subsequent determination of parent PAHs and their associated transformed nitro-PAHs (NPAH), carbonyl-PAHs (CPAH) and hydroxy-PAHs (HO-PAH) products (TPPs) is essential for reducing the time and cost of analysis. The aim of this study was to modify and optimize the pressurized fluid extraction (PFE) technique capable of simultaneous extraction and in-cell clean-up of PAHs and TPPs in urban dust standard reference material and road dust for GC-MS analyses. In this study, multivariate data analysis such as factor analysis (FA), and preference ranking organisation method for enrichment evaluation (PROMETHEE) and geometrical analysis for interactive aid (GAIA) were used to assess the performance of the methods. As the key outcome of the study, an optimized selective reaction monitoring (SRM) Triple Quadrupole (TQ) electron ionization (EI)-GC/MS for measuring PAHs and TPPs without derivatization of polar HO-PAHs was developed. The limits of detection (LOD) for parent PAHs, CPAHs, NPAHs and HO-PAHs using Shimadzu TQ were 1.0–5.0 pg, 1.0–5.0 pg, 1.0–50.0 pg, and 1.0–25.0 pg, respectively. The PROMETHEE-GAIA analysis of the results showed that a combination of 3% deactivated silica gel and activated alumina (2:1) as in-cell clean-up material, and sequential PFE extraction (200 °C ASE temperature, 9 min preheat time and 3 times extraction cycle) using 100% hexane followed by hexane/DCM (1:1) is the best condition for analytes extraction from road dust. An optimized, fast and reliable GC/MS method operated solely in electron ionization (EI) mode was developed for measuring all analytes. The outcomes of this study will contribute significantly to future research on PAHs and TPPs, thereby promoting a safe and sustainable environment.

Graphene hydrogel (GH) has attracted increasing attention in energy storage and conversion, pollutant adsorption, catalysis, sensors and tissue engineering applications. However, a good understanding of the structure-property relationship is essential to precisely tune their properties. In this work, a pH assisted hydrothermal process was used to synthesize reduced graphene oxide (rGO) hydrogels with different three-dimensional (3D) porous structures. We systematically investigated the structure-property relationships in the GH, with a focus on the effects of geometrical dimensions of the pore structure. We found that the best mechanical properties were achieved in a compact microstructure consisting of small pores but thick walls. Despite having a lower C/O ratio, the compact structure gave rise to the highest electrical conductivity, attributed to the highly interconnected 3D porous structure providing conductive pathways. On the other hand, the hydrogels prepared under basic conditions exhibited higher C/O ratio but lower mechanical and electrical properties due to the disordered pore structure with large pores and thin walls.

The adsorption behaviour of metals deposited on road surfaces undergo changes during dry weather periods, with the bioavailability varying compared to the original species, prior to incorporation in stormwater runoff. This study investigated the role of antecedent dry days on the transformation characteristics of Zn, Cu, Pb and Cd attached to different geochemical forms of road dust, in order to predict potential stormwater quality impacts. The study outcomes showed that the exchangeable fraction generally decreased with the increase in antecedent dry days, but the reducible, oxidisable and residual fractions increased. This implies that there is a time-dependent transformation of weakly bound metals in road dust to more persistent chemical forms. The transformation rate of metals was found to be in the order of Pb > Cu > Zn > Cd. Significant changes in metal distribution among the geochemical fractions were observed up to seven dry days, suggesting that during the initial antecedent dry days, the transformations can be relatively more significant. Among the analysed metals, Cd present on road surfaces has a higher potential for being bioavailable during the antecedent dry days.

Adsorption of iodate (IO3−) from concentrated solutions by LDH materials has been investigated in laboratory scale batch experiments. Very high iodate (IO3−) uptake (close to 100%) was observed in almost all experiments. Adsorption data was compared to the Langmuir and Freundlich adsorption isotherm models as well as the pseudo first and second order kinetic models. The data from the 3:1 Mg/Al LDH thermally activated to 500 °C was best described by the Freundlich isotherm and the pseudo second order model, suggesting that adsorption was a heterogeneous or multilayer process. HPLC data was used in an attempt to identify any conversion of iodate (IO3−) to iodide (I−) during the adsorption process, however, the residual concentration of iodide (I−) was close to or below the limit of detection of the particular analytical technique. This suggests that little or no conversion happened under experimental conditions.

The adsorption-desorption behaviour of heavy metals in aquatic environments is complex and the processes are regulated by the continuous interactions between water and sediments. This study provides a quantitative understanding of the effects of nutrients and key water and sediment properties on the adsorption-desorption behaviour of heavy metals in riverine and estuarine environments. The influence levels of the environmental factors were determined as conditional regression coefficients. The research outcomes indicate that the mineralogical composition of sediments, which influence other sediment properties, such as specific surface area and cation exchange capacity, play the most important role in the adsorption and desorption of heavy metals. It was found that particulate organic matter is the most influential nutrient in heavy metals adsorption in the riverine environment, while particulate phosphorus is more important under estuarine conditions. Dissolved nutrients do not exert a significant positive effect on the release of heavy metals in the riverine area, whilst dissolved phosphorus increases the transfer of specific metals from sediments to the overlying water under estuarine conditions. Furthermore, the positive interdependencies between marine-related ions and the release of most heavy metals in the riverine and estuarine environments indicate an increase in the mobility of heavy metals as a result of cation exchange reactions.

Cyanide (CN−) is one of the most hazardous ions to humans and the environment. Therefore, sensitive, and selective sensors for CN− monitoring are highly required. A novel chemosensor based on naphthalene flanked diketopyrrolopyrrole dye (TBC-DPPN) is synthesized for the direct detection of CN− in water samples by naked eye and vibrational spectroscopy (UV–Vis and fluorescence). The electron deficient carbonyl group of the lactam ring of TBC-DPPN undergoes a nucleophilic attack by the CN− thus causing the yellow color of the dye turn to colorless, and fluorescence of the dye at 527 nm to turn-off. The mechanism of CN− sensing by the TBC-DPPN sensor is confirmed by spectral measurements and density functional theory (DFT) calculations. The TBC-DPPN sensor is utilized to determine the CN− by colorimetric and fluorescence methods in water down to 0.5 and 0.05 µm, respectively, which is well below the cut off limit of 1.9 µm that is recommended by the World Health Organization (WHO). Therefore, TBC-DPPN can act as dual channel sensor with high selectivity and sensitivity for the determination of CN− in water.

In this article, the authors report the adsorption of iodide by Mg/Al LDHs and thermally activated LDH materials in laboratory scale batch experiments. The optimal Mg/Al cation ratio was 3:1while the percentage iodide uptake increased with increasing adsorbent dose up to 1 g/20 mL of solution. The effect of initial iodide concentration was investigated using the Langmuir and Freundlich adsorption isotherm models, while the pseudo second order kinetic model appeared to provide the best fit for the experimental data. High iodide uptake of over 80% could be achieved without completely eliminating dissolved or atmospheric carbonate and leaching of 131I from LDHs did not appear to be a significant problem over the period of 28 days investigated. These results demonstrate that LDHs, which are already commercially available in large quantities, are a technology that shows considerable promise for the removal of radioiodine from aqueous solution.

Highlights - Sofosbuvir metabolite was studied for the first time by Raman spectroscopy. - Cheap and disposable paper substrate was utilized for the determination of PSI-6206 by HPLC-SERS. - The use of disposable substrate eliminated the memory effect problem in the HPLC-SERS. - The SERS LOQ of PSI-6206 was 13 ng L-1 (R2 = 0.959, RSD = 5.23%), 4 orders of magnitude less than HPLC-DAD. - The HPLC-SERS method provided unique structural identification of PSI-6206 similar to HPLC-MS Abstract Sofosbuvir metabolite, 2′-deoxy-2′-fluoro-2′-C-methyluridine (PSI-6206) was studied for the first time by surface enhanced Raman spectroscopy (SERS) using the paper-based SERS substrate. The quantification limit of PSI-6206 by SERS was found to be 13 ng L−1 (R2 value = 0.959, RSD = 5.23%). For the structural and quantitative analysis of PSI-6206 in blood plasma, an interference-free HPLC-SERS method was developed and compared to HPLC-DAD and HPLC–MS methods. The SERS quantification of the drug by the paper substrate was 4 orders of magnitude more sensitive than that by the diode array detector. In addition, the SERS detection provided unique structural identification of the drug in blood plasma, similar to Mass spectroscopy detector. Due to the disposable nature of the SERS substrate, the new method does not suffer from the known “memory effect” which is known to lead to false positive identification in traditional HPLC-SERS methods. Therefore, the presented HPLC-paper SERS platform holds great potential for the sensitive and cost effective determination of drugs and their metabolites in biological fluids.

Photochemical smog, characterized by high concentrations of ozone (O3) and fine particles (PM2.5) in the atmosphere, has become one of the top environmental concerns in China. Volatile organic compounds (VOCs), one of the key precursors of O3 and secondary organic aerosol (SOA) (an important component of PM2.5), have a critical influence on atmospheric chemistry and subsequently affect regional and global climate. Thus, VOCs have been extensively studied in many cities and regions in China, especially in the North China Plain, the Yangtze River Delta and the Pearl River Delta regions where photochemical smog pollution has become increasingly worse over recent decades. This paper reviews the main studies conducted in China on the characteristics and sources of VOCs, their relationship with O3 and SOA, and their removal technology. This paper also provides an integrated literature review on the formulation and implementation of effective control strategies of VOCs and photochemical smog, as well as suggestions for future directions of VOCs study in China.

Consumption of crops grown in cadmium-contaminated soils is an important Cd exposure route to humans. The present study utilizes statistical analysis and in vitro digestion experiments to uncover the transfer processes of Cd from soils to the human body through rice consumption. Here, a model was created to predict the levels of bioaccessible Cd in rice grains using phytoavailable Cd quantities in the soil. During the in vitro digestion, a relatively constant ratio between the total and bioaccessible Cd in rice was observed. About 14.89% of Cd in soils was found to be transferred into rice grains and up to 3.19% could be transferred from rice grains to the human body. This model was able to sufficiently predict rice grain cadmium concentrations based on CaCl2 extracted zinc and cadmium concentrations in soils (R2 = 0.862). The bioaccessible Cd concentration in rice grains was also able to be predicted using CaCl2 extracted cadmium from soil (R2 = 0.892). The models established in this study demonstrated that CaCl2 is a suitable indicator of total rice Cd concentrations and bioaccessible rice grain Cd concentrations. The chain model approach proposed in this study can be used for the fast and accurate evaluation of human Cd exposure through rice consumption based on the soil conditions in contaminated regions.

Infliximab (INF) is a chimeric monoclonal immunoglobulin acting against tumor necrosis factor-alpha (TNF-α). The drug is used for the treatment of chronic autoimmune and inflammatory diseases. A target-specific nanomaterial is presented for the extraction of INF from human plasma along with a label-free surface enhanced Raman spectroscopy (SERS) method for its determination using a handheld device. A gold-coated copper oxide chip was functionalized with TNF-α and used to extract the drug from plasma. INF was recovered from the extractor by lowering the pH value to 2.5. The disulfide bond structure of the drug was then reduced and used for its oriented chemisorption onto a gold-coated copper oxide substrate for SERS measurements using the INF-specific band at 936 cm −1. The working range of the SERS method was between 10 −7 and 10 −14 M of reduced INF. The relative standard deviation (RSD), between three different measurements was 4.2% (intra-day) and 7.1% (inter-day). The quantification and detection limits of the assay (LOQ, LOD) were 0.01 pM and 1.4 fM respectively. The SERS detection was cross-validated against ELISA where 99% agreement was found between the two methods. [Figure not available: see fulltext.]

The detection of anti-TNF-α drugs require rapid, selective and sensitive biosensors that can be easily utilised at the point of care. Herein, we demonstrate a new biosensing approach that employs target-specific nanomaterial and label free surface-enhanced Raman spectroscopy (SERS) for the selective extraction and rapid determination of Adalimumab (ADB) in human blood plasma. The new method utilises the tumour necrosis factor (TNF-α) for the fabrication of a target-specific nanomaterial for extraction of ADB. The method also uses the thiol chemistry of the purified antibody drug for its chemisorption onto a gold-coated copper oxide substrate. A handheld Raman spectrophotometer is used for the determination of ADB by label free SERS. The limits of quantification (LOQ) and detection (LOD) of the purified and reduced drug by SERS were 0.10 fM and 0.03 fM respectively. ELISA was used for the cross validation of the SERS quantification of ADB where a 98.8% agreement was found between the two methods. Many proteins have disulfide bonds in their molecular structure. Therefore, the demonstrated biosensing approach can be extended for the rapid screening of other proteins and antibody drugs by developing target-specific extractor nanomaterial and utilizing the disulfide bond structure of the purified biomolecules for their label free SERS detection.

A new benzothiazole azo dye [(E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diol] (also known as “BAN”), has been synthesised and used as a chemosensor for the rapid and selective detection of mercury(II) ions in water. The pink coloured chemosensor turns blue when reacted with mercury(II) ions due to the formation of a 2 : 1 coordination complex. The complex formation causes a bathochromic shift of the chemosensor's UV absorption peak from 540 to 585 nm and turns on a highly selective fluorescence emission at 425 nm. The change in the optical property of BAN upon complexation with mercury(II) was confirmed by ab initio calculations. The new chemosensor was used to quantify mercury(II) ions in water by fluorescence spectroscopy down to 5 × 10−8 M (10 ppb). The limit of detection (LOD) of Hg2+ was 9.45 nM (1.8 ppb) which satisfies the maximum allowable Hg2+ concentration in drinking water that is set by the WHO. The BAN–Hg(II) complex was used for the determination of cysteine (Cys) in aqueous solution by UV-Vis spectroscopy down to 1 × 10−7 M. The thiol-containing amino acid preferentially coordinates the mercury ions of the BAN–Hg(II) complex. This causes dissociation of the blue-coloured complex and the liberation of the pink-coloured BAN dye. The colour change of the BAN–Hg(II) complex from blue to pink was selective to the Cys biothiol while other non-thiol containing amino acids did not cause a colour change. For the in-field application, filter paper strips were loaded with the BAN–Hg(II) complex and used as a disposable sensor for the detection of cysteine (Cys) by the naked eye. Therefore, the BAN chemosensor offers a sensitive, and rapid tool for the detection of mercury(II) in water. In addition, the BAN–Hg(II) complex can be used as a simple and selective chemosensor of the screening of purified biothiols, such cysetine, homocysteine and glutathione in biology research and pharmaceutical/food industries.

Understanding the factors influencing the build-up behaviour of different pollutants accumulated on urban roads is essential for the implementation of effective stormwater pollution mitigation strategies. Even though a significant knowledge base exists on different factors influencing hydrocarbon build-up, there is a dearth of evidence on how physicochemical properties of road dust influence hydrocarbon build-up. Accordingly, this study investigated the relationships between physicochemical properties of road dust and hydrocarbons associated with different particle size fractions of road dust. Hydrocarbons with different sources of origin in all size fractions showed a significant correlation with different soil constituents of road dust, predominantly with organic matter, amorphous matter, clay minerals and clay forming minerals of feldspars. However, the physicochemical properties influencing the hydrocarbon build-up is different among different particle size fractions. The interactions identified between hydrocarbon compounds and different minerals associated with road dust will contribute to the development of effective stormwater pollution mitigation strategies.

Co-precipitation is a common method for the preparation of layered double hydroxides (LDHs) and related materials. This review article is aimed at providing newcomers to the field with some examples of the types of co-precipitation reactions that have been reported previously and to briefly investigate some of the properties of the products of these reactions. Due to the sheer volume of literature on the subject, the authors have had to limit this article to the synthesis of Mg/Al, Zn/Al and Ca/Al LDHs by co-precipitation and directly related methods. LDHs have been synthesised from various reagents including metal salts, oxides and hydroxides. Co-precipitation is also useful for the direct synthesis of LDHs with a wide range of interlayer anions and various bases have been successfully employed to prepare LDHs. Examples of other synthesis techniques including the urea method, hydrothermal synthesis and various mechanochemical methods that are undoubtedly related to co-precipitation have also been included in this review. The effect of post synthesis hydrothermal has also been summarised.

Novel heterogeneous Fenton composite materials were developed by grafting acid precursors and nano zero-valent iron particles on an acid leached diatomite, which can sequentially generate acid and ferrous ions in situ. The results show that the composite materials can potentially solve two of the biggest obstacles, which prevent the conventional Fenton reaction from being widely and practically adopted, namely: the continuous feed of ferrous ions and the maintenance of the optimum acidic pH condition during the reaction. In this study, samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Thermogravimetric analysis and micro organic analysis. The novel materials’ degradation capacities for bisphenol A (BPA) were evaluated and optimized. This material can be easily applied to treat wastewater via Fenton-like reaction without changing pH or adding ferrous ions. The relationships between BPA removal efficiency, the amount of grafted organosilane acid precursor and doped nZVI particles on the composite materials were investigated. It is evident from the results that the novel composite materials afford highly effective removal of BPA from water at 250 mg/g. The work thus demonstrates that the novel materials could potentially be utilized for efficient remediation of recalcitrant organic compounds from the environment.

Several studies have previously demonstrated that layered double hydroxides (LDHs) show considerable potential for the adsorption of radioiodine from aqueous solution; however, few studies have demonstrated that these materials are able to store radioactive (131)I for an acceptable period. The leaching of iodide (I(-)) and iodate (IO3(-)) form Mg/Al LDHs has been carried out. Contact time appeared to be a more significant variable for the leaching of iodate (IO3(-)) compared to that of iodide (I(-)). Experimental results are fitted to the pseudo second order model, suggesting that diffusion is likely to be the rate-limiting step. The presence of carbonate in the leaching solution appeared to significantly increase the leaching of iodide (I(-)) as did the presence of chloride to a lesser extent. The maximum amount of iodate (IO3(-)) leached using ultrapure water as the leaching solution was 21% of the iodate (IO3(-)) originally present. The corresponding result for iodide (I(-)) was even lower at 3%.

The presence of radioactive iodine (radioiodine) in drinking water is a significant health hazard that originates from nuclear medicine and atomic energy industries. The application of LDHs to the removal of iodine offers potential for iodine capture and entrapment. Mg/Al and Zn/Al layered double hydroxides (LDHs) have been prepared and have been evaluated for the sorption of iodide in some small-scale batch experiments. All LDHs were prepared by the co-precipitation method and characterised by a range of techniques including powder X-ray diffraction, transmission electron microscopy and elemental analysis. Adsorption experiments were carried out at high iodide concentrations up to 1000 ppm and no control or pH or atmospheric carbonate commonly used in most studies. The highest iodide uptake of approximately 71% was observed using a 3:1 Zn/Al LDH thermally activated to 500 °C, however, a 3:1 Mg/Al LDH exhibited similar results. LDHs potentially offer a technology for the removal of iodine from aqueous media.

Inorganic-organic montmorillonites (IOMts) obtained by modifying polyhydroxy-aluminum (Al 13 )-pillared montmorillonite (AlPMt) with the cationic surfactant (C16) and zwtterionic surfactant (Z16) were investigated with the aim to remove phenol, phosphate and Cd(II) simultaneously. The structures of IOMts prepared using different surfactant doses (0.4 and 1.0CEC) strongly depended on the types and doses of the surfactants. The Al 13 contents of C16 modified AlPMts (C-AlPMts) decreased with increasing C16 loading while that of Z16 modified AlPMt (Z-AlPMts) did not. In the single adsorption system, all IOMts could efficiently remove phenol and phosphate, but not Cd(II). IOMts, however, could efficiently remove all three contaminants simultaneously in the multi-contaminant adsorption system. The adsorptions of phenol on IOMts were not affected by the other two inorganic components and vice versa. Whereas the adsorptions of phosphate and Cd(II) were significantly enhanced in the multi-contaminant system, and the adsorption of one increased with increasing initial concentration of the other one, especially the adsorption of Cd(II). The enhancements of adsorption of phosphate and Cd(II) on the IOMts with higher Al 13 content were much larger than that on IOMts with lower Al 13 content. The adsorption mechanism for phosphate and Cd(II) uptake in the multi-contaminant system possible involve the formation of phosphate-bridged ternary complexes.

Fe–montmorillonite (Fe–Mt) was prepared and tested for its potential application in the simultaneous removal of hexavalent chromium (Cr(VI)) and rhodamine B (RhB) from aqueous solution. The adsorption kinetics and capacities of Fe–Mt toward Cr(VI) and RhB were determined in relation to the initial contaminant concentration, pH of the solution and concentration of coexist contaminant. The adsorption kinetics of Cr(VI) or/and RhB in both single and simultaneous systems were investigated, which showed that an equilibrium time of a few hours was needed for the adsorption of Cr(VI) and RhB on Fe–Mt. The pseudo-second order model offers a better fit than pseudo-first order model for the Cr(VI) and RhB adsorption. Compared with the single adsorption systems, adsorption rates and quantities of Cr(VI) and RhB adsorbed on Fe–Mt were slightly enhanced in the simultaneous adsorption system. The most effective pH range for the removal of Cr(VI) and RhB was found to be 3.0–4.0. Cr(VI) adsorption isotherms were best represented by the two-site Langmuir model while RhB isotherms followed the Freundlich model. For both contaminants, the adsorption of one contaminant increases with increase in the initial concentration of the other one. Therefore, Fe–Mt could simultaneously remove Cr(VI) and RhB from water. The properties of Fe–Mt were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG). The findings of this study provide novel information for the development of clay-based adsorbents toward dyes and heavy metals.

Adsorption has been considered as an efficient method for the treatment of dye effluents, but proper disposal of the spent adsorbents is still a challenge. This work attempts to provide a facile method to reutilize the spent Mg/Al layered double hydroxide (Mg/Al-LDH) after the adsorption of orange II (OII). Herein, the spent hybrid was carbonized under the protection of nitrogen, and then washed with acid to obtain porous carbon materials. Thermogravimetric analysis results suggested that the carbonization could be well achieved above 600°C, as mass loss of the spent hybrid gradually stabilized. Therefore, the carbonization process was carried out at 600, 800, and 1000°C, respectively. Scanning electron microscope showed that the obtained carbon materials possessed a crooked flaky morphology. Nitrogen adsorption-desorption results showed that the carbon materials had large BET surface area and pore volume, e.g., 1426 m(2)/g and 1.67 cm(3)/g for the sample carbonized at 800°C. Moreover, the pore structure and surface chemistry compositions were tunable, as they were sensitive to the temperature. Toluene adsorption results demonstrated that the carbon materials had high efficiency in toluene removal. This work provided a facile approach for synthesizing porous carbon materials using spent Mg/Al-LDH.

2,4,6-trinitrotoluene (TNT) is one of the most commonly used nitro aromatic explosives in landmine, military and mining industry. This article demonstrates rapid and selective identification of TNT by surface-enhanced Raman spectroscopy (SERS) using 6-aminohexanethiol (AHT) as a new recognition molecule. First, Meisenheimer complex formation between AHT and TNT is confirmed by the development of pink colour and appearance of new band around 500 nm in UV-visible spectrum. Solution Raman spectroscopy study also supported the AHT:TNT complex formation by demonstrating changes in the vibrational stretching of AHT molecule between 2800-3000 cm−1. For surface enhanced Raman spectroscopy analysis, a self-assembled monolayer (SAM) of AHT is formed over the gold nanostructure (AuNS) SERS substrate in order to selectively capture TNT onto the surface. Electrochemical desorption and X-ray photoelectron studies are performed over AHT SAM modified surface to examine the presence of free amine groups with appropriate orientation for complex formation. Further, AHT and butanethiol (BT) mixed monolayer system is explored to improve the AHT:TNT complex formation efficiency. Using a 9:1 AHT:BT mixed monolayer, a very low detection limit (LOD) of 100 fM TNT was realized. The new method delivers high selectivity towards TNT over 2,4 DNT and picric acid. Finally, real sample analysis is demonstrated by the extraction and SERS detection of 302 pM of TNT from spiked.

Meropenem (MPN), a broad spectrum β-lactam antibiotic, has been increasingly used in the treatment of moderate to severe bacterial infections. However, due to its short plasma half-life and chemical instability in solution form, it has been challenging to use in the intravenous formulation. This study aims to develop and characterize MPN dry powder inhaler (DPI) formulation for pulmonary delivery. The inhalable MPN particles (1-5µm) were prepared by micronization. Lactose, L-leucine and magnesium stearate (MgSt) were used in the powder formulation as carriers and dispersibility enhancers. The formulations were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman confocal microscopy, X-Ray powder diffraction analysis (PXRD), and differential scanning calorimetry (DSC) methods. The concentration of MPN was determined by using a validated HPLC method. The Fine Particle Fraction (FPF) of meropenem from powder mixtures was determined by a Twin Stage Impinger (TSI) at a flow rate of 60 L/min. The FPF of the original MPN was 1.91 % which was significantly increased to 37.5 % for the formulations with excipients. No physical interactions between the drug and the excipients observed. This study revealed the potential of a stable meropenem DPI formulation for pulmonary delivery.

Two-dimensional (2D) MXene, as an important member of the emerging 2D nanomaterials, has received much attention in recent years, especially in energy-related fields. Unfortunately, the controllable synthesis of high-purity MXenes in a scalable way is still a challenge, due to the usual utilization of hazardous etching agents. It is highly desired that a simple, controllable, and effective approach is available for producing MXene in a green manner. In this work, an innovative thermal reduction strategy is proposed for the fabrication of MXenes from the corresponding sulfur-containing MAX phases, in which the weakly bonded S atoms react with hydrogen to form a volatile gas and leave 2D graphene-like Ti2C nanosheets. As a promising anode material for electrochemical Li+ ion storage, the resulting MXene demonstrated satisfying initial discharge capacities of ~200 mAh g−1. Furthermore, the capacity remained at ~70 mAh g−1 over 130 cycles even at a high rate of 2.0 A g−1, indicating a good rate capability and cycling stability. This work thus offers a novel approach for MXene fabrication and enriches MXene-based electrode materials for energy devices.

Tumor necrosis factor alpha (TNF-α) is a cytokine that plays a critical role in medical conditions such cardiovascular diseases, rheumatoid arthritis, inflammatory bowel disease, Alzheimer’s and cancer. Herein, we present a new method for the determination of TNF-α by surface enhanced Raman spectroscopy (SERS). A new benzothiazole azo dye (BAN) was used as a Raman probe to detect the cytokine after its selective extraction from blood plasma using a target-specific antibody-functionalised extractor chip. The disulfide bond structure of the extracted TNF-α was reduced to generate free sulfhydryl (SH), terminal groups that adsorb preferentially onto a BAN-functionalised SERS substrate and displace the BAN Raman reporter on the substrate surface. This causes the SERS spectrum of BAN to quench proportionally with the cytokine concentration. Using this SERS quenching sensor, TNF-α was quantified down to 1 × 10−14 M (173 pg/L). The quantification of the cytokine by the SERS quenching method was cross-validated against enzyme-linked immunosorbent assay (ELISA) and the percent agreement between the two measurements was found to be 93.39 %. Since many proteins and peptides have disulfide bonds in their molecular structures, the new SERS quenching method can be extended for their ultrasensitive quantification after selective extraction from biological fluids.

We demonstrate a novel method for the selective extraction and electrochemical detection of S100β disease biomarker. The protein is extracted from blood plasma using target-specific gold coated magnetic nanoparticles. This is followed by the rapid reduction of the disulfide bond structure of the purified protein using chronoamperometry and its immobilisation onto a nanostructured gold electrode. The protein concentration is quantified down to 10 pM (120 ng l−1), by electrochemical desorption using differential pulse voltammetry (DPV). The new method was used to extract and determine S100β in spiked blood plasma and the DPV quantification was cross-validated against enzyme-linked immunosorbent assay (ELISA) where the percent agreement between the two measurements was 96.54%. Therefore, this method has strong potential for the sensitive determination of S100β. In addition, 65% of proteins have similar disulfide bond structure. Therefore, the new method can be utilised for the determination of many disease biomarkers after optimizing specific extractor nanomaterial for the target biomarker.

Analysis of soil samples around pristine and major gold-mining areas in Ghana was carried out for heavy metals as part of a larger soil contamination and metal background study. The surface soil samples were digested using microwave digester (aqua regia) and analyzed with ICP-MS for As, Cd, Hg, Zn, Co, Cu, Mn, Fe, Al, V, Cr, and Pb. The average concentrations (mg/L) for the metals ranged from 0.01 ± 0.01 (Cd) to 86,859.36 ± 47.07 (Fe) for the pristine sites, and 0.01 ± 0.01 (Cd) to 59,006.95 ± 79.06 (Fe) for the mining sites. Mercury was below the detection limit of the analytical instrument (0.029). The concentrations of heavy metals from this study were used to assess their contamination levels, and health risks. The results showed that, the metals ranked by severity of health risks as As > Pb > Cr > Cd. Principal component analysis (PCA) and cluster analysis showed two groupings with the PCA showing metals variability explained by 79.02%. Results from the PCA and Cluster analysis indicate anthropogenic sources of the metals which may be emanating from gold-mining activities. Results from multi-criteria ranking and pattern recognition employing PROMETHEE and GAIA revealed major contribution of the metals from the mining sites with metal variability explained by 72.83%. This is the first time a multi-criteria approach is employed to characterize heavy metal contamination in Ghana, and the study nevertheless brought to light the impact of mining on human health and the environment with implications for other mineral areas around the globe.

The detection of protein biomarkers for the clinical diagnosis of diseases requires selective and sensitive methodologies and biosensors that can be easily used at pathology laboratories and points of care. An ideal methodology would be able to conduct multimode screening of low and high concentrations of proteins in biological fluids using recyclable platforms. In this work, we demonstrate a novel nanosensing methodology for the dual detection of cystatin C (CST-C), as a protein biomarker model, in blood plasma by surface-enhanced Raman spectroscopy and electrochemistry. The new methodology utilizes the thiol chemistry of biomolecules to develop a target-specific and recyclable extractor chip for the rapid isolation of protein biomarkers from blood plasma. This is followed by the rapid reduction of the disulfide bonds within the isolated protein to influence its oriented immobilization onto a conductive gold coated silicon nanopillar substrate via stable gold–sulfur (Au–S) bonds. The oriented immobilization led to reproducible surface-enhanced Raman spectroscopy (SERS) measurements of the reduced protein (RSD = 3.8%) and allowed for its direct electrochemical determination. After the SERS measurement, differential pulse voltammetry (DPV) was used to desorb the analyte from the substrate and generate a reduction current that is proportional to its concentration. CST-C was determined down to 1 pM and 62.5 nM by SERS and DPV, respectively, which satisfies the requirements for monitoring Alzheimer’s and kidney failure diseases. The new dual nanosensing methodology has strong potential for miniaturization in a lab-on-a-chip platform for the screening of many protein biomarkers that have a disulfide bond structure.

Heavy metal contamination of selected rivers in Ghana was studied as part of a bigger project aimed at setting background standard for heavy metals in the Ghanaian environment. Water samples were collected from major mining and eight pristine areas. The samples were acid digested with aqua-regia and analyzed with ICP-MS for As, Cd, Hg, Zn, Cu, Mn, Fe, Cr, Al, V, Co, Ni, and Pb. The average concentrations (mg/L) from the pristine sites ranged from 0.002 ± 0.00(As) to 0.929 ± 0.06 (Fe) and 0.002 ± 0.00 (Pb) to 20.355 ± 5.60 (Fe) from the mining sites. With the exception of Al, Fe, and Mn, the metals level were found to be within the WHO and USEPA guideline limits. Hazard quotients (HQ) for ingestion and dermal contact for pristine and mining samples ranged from 3.00E-04 (Cu) to 0.84 (Cr) and 2.40E-06 (Cu) to 7.44 (As), respectively. The carcinogenic risk (CR) for ingestion and dermal contact ranged from 5.03E-06 to 1.71E-07 (Cr) and 4.22E-08 to 1.44E-09 (Cr), respectively. Arsenic showed a CR value higher than the acceptable limit (1.8E-02) from the mining sites which poses carcinogenic health threat. Multicriteria ranking suggests Birim river (EAM) as the most contaminated. The pattern recognition and multicriteria approach in characterizing the heavy metal contamination (for the first time in the case of Ghana) from the various sites will provide fresh insights into the risk assessment of heavy metals in contaminated surface waters.

A label free electrochemical detection method for the rapid detection of recombinant human erythropoietin (rhuEPO) has been developed. In this method, we modified the rhuEPO structure for its direct sensing without using a complex signal amplification strategy. The protein was selectively extracted from blood plasma sample using target-specific magnetic beads. After releasing rhuEPO from the magnetic beads, its disulfide bonds were electrochemically reduced and the protein was spontaneously assembled onto a nanostructured gold electrode via Au-S bonds formation. For electrochemical quantification, the reduced protein was desorbed from the electrode surface using differential pulse voltammetry (DPV). The desorption current was proportional to the concentration of rhuEPO in the range 1 pM – 1000 pM. By cross-validating against ELISA, we found a 104.85 ± 3.35% agreement between the results obtained using the electrochemical biosensor and ELISA. Therefore the developed method has a strong potential for the sensitive detection of rhuEPO doping in sports as well as its rapid screening and pathology labs.

Wet-milling protocol was employed to produce pressed powder tablets with excellent cohesion and homogeneity suitable for laser ablation (LA) analysis of volatile and refractive elements in sediment. The influence of sample preparation on analytical performance was also investigated, including sample homogeneity, accuracy and limit of detection. Milling in volatile solvent for 40 min ensured sample is well mixed and could reasonably recover both volatile (Hg) and refractive (Zr) elements. With the exception of Cr (-52%) and Nb (+26%) major, minor and trace elements in STSD-1 and MESS-3 could be analysed within ±20% of the certified values. Comparison of the method with total digestion method using HF was tested by analysing 10 different sediment samples. The laser method recovers significantly higher amounts of analytes such as Ag, Cd, Sn and Sn than the total digestion method making it a more robust method for elements across the periodic table. LA-ICP-MS also eliminates the interferences from chemical reagents as well as the health and safety risks associated with digestion processes. Therefore, it can be considered as an enhanced method for the analysis of heterogeneous matrices such as river sediments.