We investigate whether incubating bacteria in a growth medium that contains gold nanoparticles can provide a more convenient platform for determining bacterial concentration than existing techniques. Citrate AuNPs were mixed with Luria-Bertani broth, seeded with known concentrations of live bacteria, and the mixture monitored for 12 h. Changes to the optical properties were detected as the bacteria proliferated. Peak wavelength of the longer wavelength particle-particle plasmon resonance, the inflection point associated with this peak, an increase in overall attenuance at 400 nm, spectral correlation to a reference spectrum and aggregation factor were each influenced by the starting bacterial concentration. The wavelength of the particle-particle plasmon resonance provided the most consistent results. Incubation times of 6 to 8 h provided optimum sensitivity using this signal alone, with a detection limit of 2.1 × 104 CFU/mL at 95% confidence. Since each parameter extracted from the experimental spectra was subject to some scatter, a three-channel calibration based on the equally weighted average of the individual calibration curves based on attenuance, wavelength of the aggregation plasmon peak and spectral correlation was also investigated. This provided an even lower detection limit of 360 CFU/mL at 95% confidence.

The use of pre-precursors to illicitly manufacture 3,4-methylenedioxyphenyl-2-propanone (MDP2P) for the synthesis of 3,4-methylenedioxymethylamphetamine (MDMA) has emerged in clandestine laboratories. Methyl 3-(3,4-methylenedioxyphenyl)-2-methyl glycidate (MMDMG) and ethyl 3-(3,4-methylenedioxyphenyl)-2-methyl glycidate (EMDMG) have recently been seized in clandestine laboratories in New South Wales, Australia. These glycidate esters can be converted to MDP2P via acid or base hydrolysis. This study investigated factors influencing MDP2P yield from MMDMG and EMDMG through both pathways. For acid hydrolysis, hydrochloric, sulphuric, phosphoric and acetic acids were examined at different reaction times and temperatures. Reactions at 100°C produced higher MDP2P yields than those at room temperature, and 18 h was sufficient for complete conversion. Hydrochloric and sulphuric acids gave the highest yields after 18 h at 100°C (79% and 78%, respectively), phosphoric acid gave moderate conversion (~30%), and acetic acid produced poor yields (< 10%). The conversion proceeded via two previously unreported diol-ester intermediates. Base hydrolysis involved heating glycidate esters with sodium hydroxide in alcohol, forming sodium piperonyl methyl ketone (PMK) glycidate, followed by reaction with aqueous acid. Heating MMDMG in methanol or EMDMG in ethanol for 5 h produced sodium PMK glycidate. This intermediate was unstable in acidic aqueous solution and rapidly converted to MDP2P at room temperature. Yields obtained using hydrochloric, sulphuric and phosphoric acids (73%, 71% and 69%, respectively) were comparable to acid hydrolysis, whereas acetic acid produced lower yields (25%). This work may assist law enforcement agencies to predict illicit drug yields from pre-precursors and support investigations into emerging illicit drug synthesis trends.

Tyramide signal amplification, used in immunohistochemistry to image low-abundance biomolecules, has seen adaptation beyond conventional microscopy and is utilized in flow cytometry and electron microscopy. Here, we applied tyramide signal amplification to image biomolecules via elemental mass spectrometry imaging (MSI). Elemental MSI techniques such as laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) are used to image biomolecules via metal-conjugated probes, and resolution is typically hampered by a low detection sensitivity. We report the synthesis of a bespoke ruthenium complex (TyrRu) for tyramide amplification and describe its application as a multimodal analyte to image and quantify glial fibrillary acidic protein in mouse brain by complementary immunofluorescence and elemental MSI. Pairing TyrRu and avidin-biotin-HRP amplification produced a signal-to-noise ratio 2× higher than that obtained with a commercial metal-chelating polymer, allowing LA-ICP-MS image resolution of 1 μm. Data obtained using immunofluorescence and LA-ICP-MS showed excellent biomolecule agreement (r = 0.86). TyrRu was also applied alongside primary-conjugated antibodies in a multiplexed analysis, and the enhanced detection sensitivity facilitated the generation of an image with submicrometer resolution after super-resolution reconstruction.

Although incineration is currently the primary method for the disposal of seized illicit drugs, alternative methods for the disposal of illicit drugs may be necessary to provide safer and more accessible alternatives. Chemical oxidation processes have been identified as a promising alternative method to degrade illicit drugs. Using commercially available reagents and established industry processes, chemical degradation holds potential as an alternative drug disposal technique. This study investigated the oxidants ozone, sodium hypochlorite, trichloroisocyanuric acid, hydrogen peroxide, OXONE, sodium percarbonate, and peracetic acid for their potential to degrade illicit amphetamine-type stimulants using β-phenethylamine (PEA) as an exploratory analog. Oxidants and conditions that showed the highest degradation efficiency with PEA were applied to methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyamphetamine (MDA). Transformation products were identified using gas chromatography-mass spectrometry, and degradation was quantified using a fit-for-purpose method via liquid-chromatography quadrupole time-of-flight mass spectrometry. Of the oxidants explored, ozone performed the best, leading to high degradation efficiencies of methamphetamine (95%), amphetamine (86%), MDMA (100%), and MDA (100%) after 72 h of exposure. Sodium hypochlorite was also highly effective for the degradation of methamphetamine and amphetamine, while trichloroisocyanuric acid was particularly effective for MDMA and MDA. All the major transformation products of degradation were tentatively identified, with only one of 10 listed as a controlled, scheduled, or restricted substance. This research demonstrates how chemical degradation can provide a novel alternative to incineration for the destruction of amphetamine-type stimulants, providing a sustainable, long-term, and accessible method of illicit drug disposal.

In situ imaging of proteins, RNA, immune cells and other biomolecules is necessary to determine their function, interactions and roles in disease pathology. Increasingly, this is achieved via metal-conjugated probes in conjunction with elemental mass spectrometry imaging (MSI). This targeted technique is capable of simultaneously imaging up to 40 analytes, in comparison to the traditional bioimaging techniques that use fluorescent or chromogenic reagents that are typically restricted to less than four analytes without complex sample handling and analysis workflows. These analyses, however, are not straightforward, with a number of factors that require optimization. They require the use of probes specific to the target biomolecules, which are conjugated with analytes detectable by elemental MSI. Here, we summarize the MSI technology, the types of biological probes used for identification, and the forms of metal analytes used. We provide examples of their application including understanding cancer cell heterogeneity to direct clinical trials, which may impact clinical diagnostics and personalized medicine. We conclude with future perspectives on the potential of the technique and what is required to meet it. Elemental mass spectrometry imaging of biomolecules provides detailed knowledge of their abundance and location within tissue samples. This Review highlights the analytical instrumentation and strategies used to bring this technique from a research tool to clinical studies.

The disposal of seized illicit drugs is highly dependent on incineration methods. Accessible alternatives for the destruction and disposal of illicit drugs may be required due to operational or risk management strategies. In this review, alternative methods of illicit drug disposal are evaluated, highlighting thermal, chemical, biological and miscellaneous degradation techniques. Chemical degradation of illicit drugs offers the most promising alternative to incineration. Oxidative processes utilise commercially available reagents and are accessible, with some methods already established as industry processes. Advanced oxidation processes have short run times (<24 h) and can completely mineralise organic compounds, overcoming the limitation of forming undesired transformation products. Other feasible methods for drug degradation include bacterial growth and gamma irradiation. It is apparent, however, that there is currently no universal alternative method for drug degradation, as diverse classes of drugs exhibit different degradation characteristics. In some instances, harmful compounds can be produced from the degradation of the illicit drugs although if the transformation products are not illicit, they can be integrated into existing chemical waste procedures using appropriate hazardous waste protocols.

Alkyne compounds have emerged as promising stabilising ligands for gold nanoparticles, with potential applications in sensing, catalysis and biological imaging. Several examples of alkynide-stabilised gold nanoparticles have been reported although most use a mixed-ligand system that requires additional stabilising agents. Thus, a facile and size controllable synthesis of gold nanoparticles stabilised exclusively with alkyne compounds is highly desirable. Here we report dec-1-ynide@AuNPs that were synthesised by reduction of a Au(I) dec-1-ynide complex to give nanoparticles with diameter of similar to 3.4 nm and are stable in air for up to 2 months. 1H NMR spectra indicate that the particles have a shell that contains gold(I) species surrounding a core of gold(0) atoms. The synthetic technique was modified to increase the size of the AuNPs but the larger AuNPs were stabilised predominantly by tetraoctylammonium bromide (TOAB). Methods that utilised reduction of Au(III) chloride with the phase transfer agent TOAB resulted in bidisperse AuNPs with diameters of similar to 9 nm and similar to 3 nm. Variation of the synthesis conditions did not have a significant effect on the particle sizes and residual TOAB was required to maintain particle stability.

The thermosalient transformation in nickel(II) bis(diisopropyl)dithiocarbamate has been investigated using selective deuteration. The deuterated crystals undergo a reversible displacive phase transition that is ∼4 K higher in temperature compared to the protonated analogue. Neutron, synchrotron, density-functional theory, and calorimetric techniques were utilized to demonstrate the substantial effect of deuterium. All techniques demonstrated the equivalence of the mechanism on an atomic scale between the protonated and deuterated complexes. The data collected in this study reveal details of the changes of atomic motion that underpin the thermosalience inherent in this system. Deuterium decreased the frequency of atomic vibrations thus increasing the temperature of the observed transformation. This study represents a key advancement in the field of thermosalient molecular systems and provides insights into the control and manipulation of thermosalient materials.

The thermal behaviour of ligand-stabilised gold nanoparticles (AuNPs) is an important consideration when using these materials to form gold films via sintering. AuNPs stabilised with butanethiol and hexadecanethiol ligands displayed quite different properties upon heating up to their sintering temperatures. Films of AuNPs bearing the longer chain stabilising ligand hexadecanethiol become liquids at 56 °C. This temperature corresponds to the melting point of dihexadecyl disulfide, a known product that forms when such AuNPs are heated. No liquid phase was observed for butanethiol-stabilised AuNPs at any temperature. Films of the hexadecanethiol-stabilised AuNPs had high resistances (> 100 MΩ) at room temperature and the short-chain butanethiol-stabilised AuNPs had resistances in the kΩ range. Small-angle X-ray scattering data showed that the butanethiol-stabilised AuNPs begin to coarsen at 140 °C whilst the hexadecanethiol particles began to coarsen 90 °C.

4-Chloroisocoumarin compounds have broad inhibitory properties against serine proteases. Here, we show that selected 3-alkoxy-4-chloroisocoumarins preferentially inhibit the activity of the conserved serine protease High-temperature requirement A of Chlamydia trachomatis. The synthesis of a new series of isocoumarin-based scaffolds has been developed, and their anti-chlamydial properties were investigated. The structure of the alkoxy substituent was found to influence the potency of the compounds against High-temperature requirement A, and modifications to the C-7 position of the 3-alkoxy-4-chloroisocoumarin structure attenuate anti-chlamydial properties.

Elemental gold was formed by thermolysis of gold(III) dithiocarbamate single-source precursors, which exist as two complexes. The complexes were readily synthesised from the reaction between chloroauric acid and sodium di-isopropyldithiocarbamate and could be isolated from each other. The thermal decomposition processes were evaluated using thermogravimetry and electrical resistance measurements. The structure and purity of the resultant gold was examined using scanning electron microscopy. The resultant gold materials were drastically different and dependent on the thermolysed complex. The reaction between gold(III) chloride and sodium di-isopropyldithiocarbamate produces two compounds. Sub-micron sized gold microcrystals are produced when the complexes are thermally decomposed in the solid-state. The morphology of the resultant gold microcrystals is determined by the choice of complex. image

AbstractRecent advances in solar‐driven interfacial evaporation (SDIE) have led to high evaporation rates that open promising avenues for practical utilization in freshwater production and industrial application for pollutant and nutrient concentration, and resource recovery. Breakthroughs in overcoming the theoretical limitation of 2D interfacial evaporation have allowed for developing systems with high evaporation rates. This study presents a comprehensive review of various evaporator designs that have achieved pure evaporation rates beyond 4 kg m−2 h−1, including structural and material designs allowing for rapid evaporation, passive 3D designs, and systems coupled with alternative energy sources of wind and joule heating. The operational mechanisms for each design are outlined together with discussion on the current benefits and areas for improvement. The overarching challenges encountered by SDIE concerning the feasibility of direct integration into contemporary practical settings are assessed, and issues relating to sustaining elevated evaporation rates under diverse environmental conditions are addressed.

The accumulation of iron in dopaminergic neurons can cause oxidative stress and dopaminergic neuron degeneration. Iron chelation therapy may reduce dopaminergic neurodegeneration, but chelators should be targeted towards dopaminergic cells. In this work, two series of compounds based on 8-hydroxyquinoline and deferiprone, iron chelators that have amphetamine-like structures, have been designed, synthesized and characterized. Each of these compounds chelated iron ions in aqueous solution. The hydroxyquinoline-based compounds exhibited stronger iron-binding constants than those of the deferiprone derivatives. The hydroxyquinoline-based compounds also exhibited greater free radical scavenging activities compared to the deferiprone derivatives. Molecular dynamics simulations showed that the hydroxyquinoline-based compounds generally bound well within human dopamine transporter cavities. Thus, these compounds are excellent candidates for future exploration as drugs against diseases that are affected by iron-induced dopaminergic neuron damage, such as Parkinson’s disease.

Understanding and controlling the sintering behaviour of gold nanoparticles is important in the field of ligand-protected nanoparticles for their use as precursors for thin film fabrication. Lowering the temperature of the sintering event of gold nanoparticles by facilitating desorption of the ligand through oxidation can provide compatibility of sintered gold nanoparticle thin films onto heat-sensitive substrates. Here we examine the processes by which 1-butanethiol-protected gold nanoparticles sinter under an ozone-rich environment. Upon heating, an ozone-rich environment significantly reduces the temperature of the sintering event when compared to sintering under ambient conditions. At room temperature, exposure to an ozone-rich environment induces sintering over a period of 2.5 h. Upon exposure to ozone, the surface-bound butanethiol ligands are oxidised to 1-butanesulfonic acid which facilitates sintering.

Isoquinoline derivatives exhibit a range of biological properties, including antibacterial activity, and are thus attractive as a scaffold for developing broad-spectrum antibacterial compounds. A series of six isoquinoline-based compounds were synthesized using the reaction of 6,7-dimethoxy-1-methyl-3,4-dihydroisoquinoline with dimethyl acetylenedicarboxylate (DMAD) to provide the tricyclic (2Z)-[2-oxo-5,6-dihydropyrrolo[2,1,a]isoquinolin-3-ylidene]-2-ethanoate. The [2 + 3] cycloaddition of DMAD with C-6 and C-7 substituted 1-methyl-3,4-dihydroisoquinolines proceeded using aryl ethers or unsubstituted compounds, but not with amine, amide or nitro moieties at the C-7 position. Compounds 8d and 8f were found to have antibacterial properties against some Gram-positive pathogens (Staphylococcus aureus—8d = 16 µg/mL, 8f = 32 µg/mL; Streptococcus pneumoniae—8f = 32 µg/mL; and Enterococcus faecium—8d = 128 µg/mL, 8f = 64 µg/mL). Evaluation of their cytotoxic properties against mammalian cell lines revealed some cytotoxic effects (8b and 8d, 125 µM, 24 h, HEp-2 cells) and (8a, 8b, 8d = 125 µM, 8f = 62.5 µM, 24 h, McCoy B cells), suggesting limitations in their antibacterial applications without further development.

Understanding and controlling the sintering behavior of gold nanoparticles is important for applications such as printed electronics, catalysis and sensing that utilise these materials. Here we examine the processes by which thiol-protected gold nanoparticles thermally sinter under a variety of atmospheres. We find that upon sintering, the surface-bound thiyl ligands exclusively form the corresponding disulfide species when released from the gold surface. Experiments conducted using air, hydrogen, nitrogen, or argon atmospheres revealed no significant differences between the temperatures of the sintering event nor on the composition of released organic species. When conducted under high vacuum, the sintering event occurred at lower temperatures compared to ambient pressures in cases where the resulting disulfide had relatively high volatility (dibutyl disulfide). Hexadecylthiol-stabilized particles exhibited no significant differences in the temperatures of the sintering event under ambient pressures compared to high vacuum conditions. We attribute this to the relatively low volatility of the resultant dihexadecyl disulfide product.

The organic impurity profile of 3,4-methylenedioxyamphetamine (MDA) synthesised from helional via the "twodogs" method was examined to identify route-specific and condition-specific impurities. The synthesis used a condensation reaction, followed by a Beckmann rearrangement, then Hofmann rearrangement, and then conversion to a hydrochloride salt. Two chlorinating agents were investigated for the Hofmann rearrangement reaction, trichloroisocyanuric acid (TCCA) and sodium hypochlorite. Three route-specific impurities were identified in MDA using TCCA, and two of these impurities were condition-specific such that the impurities that formed were dependent on the alcohol used as solvent. Three additional impurities were identified as non-route-specific as they have previously been identified in MDA synthesised from 3,4-methylenedioxycinnamic acid or piperonal. These non-route-specific impurities were also identified in MDA synthesised using sodium hypochlorite. No impurities were detected in MDA hydrochloride. This study identified route- and condition-specific organic impurities in MDA synthesised via the "twodogs" synthetic route using helional as starting material. The results in this study provide further understanding into the illicit synthesis of MDA and highlight the expanding nature of precursors used for illicit drug manufacture. It provides valuable information to decision makers to enact legislative measures and restrict precursors of concern.

This study developed a solar evaporator by uniformly growing polydopamine nanowires (PDA NWs) on porous nickel foam (NF) substrate using a straightforward in situ approach. The synthesized material exhibited unique nanostructures, substantial hydrophilicity, and high porosity resulting in excellent light harvesting covering much of the solar spectrum. In addition, the utilized polystyrene foam support and cotton cloth resulted in a fast water supply to the evaporator along with heat localization. Good solar water evaporation rate of 1.39 kg m(-2)h(-1), with a photothermal conversion efficiency of 87.8 % was achieved at one sun (1 kW m(-2)) illumination. The PDA NWs-NF evaporator displayed high-efficiency toward salt ions rejection and met the standard required for potable water. The synthesized material displayed good reusability and stability performance in real seawater and brine (75 g/L NaCl). The self-desalting capability of the prepared evaporator is driven via chemical advection and diffusion, resulting to fast salt dissolution. Our approach in fabricating cost-effective, scalable and environmentally friendly solar-thermal converter could meet the practical needs for solar-driven seawater desalination especially for remote communities.