Gold-sputtered Blu-ray discs: simple and inexpensive SERS substrates for sensitive detection of melamine.

Nanostructured gold substrates provide chemically stable, signal-enhancing substrates for the sensitive detection of a variety of compounds through surface-enhanced Raman spectroscopy (SERS). Recent developments in advanced fabrication methods have enabled the manufacture of SERS substrates with repeatable surface nanostructures that provide reproducible quantitative analysis, historically a weakness of the SERS technique. Here, we describe the novel use of gold-sputtered Blu-ray disc surfaces as SERS substrates. The unique surface features and composition of the Blu-ray disc recording surface lead to the formation of gold nano-islands and nanogaps following simple gold sputtering, without any background peaks from the substrate. The SERS performance of this substrate is strong and reproducible with an enhancement factor (EF) of 10(3) for melamine. A limit of detection (LOD) for this compound of 70 ppb and average reproducibility of ±12 % were achieved. Gold-sputtered Blu-ray discs thus offer an excellent alternative to more exotic gold SERS substrates prepared by advanced, time-consuming and expensive methods. Graphical abstract AFM 3D images of 1-µm(2) sections of uncoated and gold-sputtered recordable Blu-ray disc (BD-R) surfaces and the SERS signal obtained on the gold-sputtered surface for a 1000 ppm aqueous solution of melamine.

Portable System for In-Clinic Differentiation of Skin Cancers from Benign Skin Lesions and Inflammatory Dermatoses.

The exquisite sensitivity of Raman spectroscopy for detecting biomolecular changes in skin cancer has previously been explored; however, this mostly required analysis of excised tissue samples using bulky, immobile laboratory instrumentation. In this study, the technique was translated for clinical use with a portable Raman system and customized fiber optic probe and applied to differentiation of skin cancers from benign lesions and inflammatory dermatoses. The aim was to provide an easy-to-use, easy-to-manage assessment tool for clinicians to use in their daily patient examination routine to perform rapid Raman measurements of skin lesions in vivo. Using this system, >867 spectra were measured in vivo from 330 patients with a wide variety of different benign skin lesions (n = 603), inflammatory dermatoses (n = 140), and skin cancers (n = 124). Ethnicities represented were 70% European; 16% Asian; 6% Maori; 5% Pacific people; and 4% Middle East, Latin American, and African. Accurate differentiation of skin cancers from benign lesions and inflammatory dermatoses was achieved using partial least squares discriminant analysis, with area under curve for the receiver operator curves for external validation sets ranging from 0.916 to 0.958. This study shows evidence for robust clinical translation of Raman spectroscopy for rapid, accurate diagnosis of skin cancer.

Direct writing of conducting polymers.

Described herein is a new printing method-direct writing of conducting polymers (CPs)-based on pipette-tip localized continuous electrochemical growth. A single barrel micropipette containing a metal wire (Pt) is filled with a mixture of monomer, supporting electrolyte, and an appropriate solvent. A droplet at the tip of the pipette contacts the substrate, which becomes the working electrode of a micro-electrochemical cell confined to the tip droplet and the pipette. The metallic wire in the pipette acts as both counter and reference electrode. Electropolymerization forms the CP on the working electrode in a pattern controlled by the movement of the pipette. In this study, various width poly(pyrrole) 2D and 3D structures are extruded and characterized in terms of microcyclic voltammetry, Raman spectroscopy, and scanning electron microscopy.

Direct laser writing of hydrophobic and hydrophilic valves in the same material applied to centrifugal microfluidics.

In this study, we utilize nanosecond and femtosecond direct laser writing for the generation of hydrophobic and hydrophilic microfluidic valves on a centrifugal microfluidic disk made of polycarbonate, without the need for wet-chemistry. Application of a femtosecond (fs) laser at 800 nm resulted in an increased contact angle, from ∼80° to ∼160°, thereby inducing the formation of a hydrophobic surface. In contrast, employing a nanosecond (ns) laser at 248 nm led to the formation of superhydrophilic surfaces. Morphological studies identified the enhancement in the surface roughness for the hydrophobic surfaces and the creation of smooth patterns for the hydrophilic surfaces. Chemical modifications in the laser-ablated samples were confirmed via Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. These spectroscopic examinations revealed an increase of hydrophilic chemical groups on both surfaces, with a more pronounced increase on the nanosecond laser-modified surface. Furthermore, these surfaces were used as a case study for centrifugal microfluidic valves. These modified surfaces demonstrated peculiar pressure responses. Specifically, the hydrophobic valves necessitated a 29% increase in pressure for droplet passage through a microchannel. On the other hand, the superhydrophilic valves exhibited enhanced wettability, decreasing the pressure requirement for fluid flow through the modified area by 39%. However, similarly to the hydrophobic valves, the fluid exiting the hydrophilic valve area required an increased pressure. Overall, our study shows the potential for tailoring valve functionality in microfluidic systems through precise surface modifications using laser technology.

Raman spectroscopy and mass spectrometry identifies a unique group of epidermal lipids in active discoid lupus erythematosus.

Discoid lupus erythematosus (DLE) is the most common form of cutaneous lupus1. It can cause permanent scarring. The pathophysiology of is not fully understood. Plasmacytoid dendritic cells are found in close association with apoptotic keratinocytes inferring close cellular signalling. Matrix Associated Laser Desorption Ionisation (MALDI) combined with Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) is an exquisitely sensitive combination to examine disease processes at the cellular and molecular level. Active areas of discoid lupus erythematosus were compared with normal perilesional skin using MALDI combined with FT-ICR-MS. A unique set of biomarkers, including epidermal lipids is identified in active discoid lupus. These were assigned as sphingomyelins, phospholipids and ceramides. Additionally, increased levels of proteins from the keratin, and small proline rich family, and aromatic amino acids (tryptophan, phenylalanine, and tyrosine) in the epidermis are observed. These techniques, applied to punch biopsies of the skin, have shown a distinctive lipid profile of active discoid lupus. This profile may indicate specific lipid signalling pathways. Lipid rich microdomains (known as lipid rafts) are involved in cell signalling and lipid abnormalities have been described with systemic lupus erythematosus which correlate with disease activity.

Raman spectroscopy system for real-time diagnosis of clinically significant prostate cancer tissue.

Prostate cancer (PCa) is a significant healthcare problem worldwide. Current diagnosis and treatment methods are limited by a lack of precise in vivo tissue analysis methods. Real-time cancer identification and grading could dramatically improve current protocols. Here, we report the testing of a thin optical probe using Raman spectroscopy (RS) and classification methods to detect and grade PCa accurately in real-time. We present the first clinical trial on fresh ex vivo biopsy cores from an 84 patient cohort. Findings from 2395 spectra measured on 599 biopsy cores show high accuracy for diagnosing and grading PCa. We can detect clinically significant PCa from benign and clinically insignificant PCa with 90% sensitivity and 80.2% specificity. We also demonstrate the ability to differentiate cancer grades with 90% sensitivity and specificity ≥82.8%. This work demonstrates the utility of RS for real-time PCa detection and grading during routine transrectal biopsy appointments.

Understanding the Chemical Mechanism behind Photoinduced Enhanced Raman Spectroscopy.

Photoinduced enhanced Raman spectroscopy (PIERS) is a new surface enhanced Raman spectroscopy (SERS) modality with a 680% Raman signal enhancement of adsorbed analytes over that of SERS. Despite the explosion in recent demonstrations, the PIERS mechanism remains undetermined. Using X-ray and time-resolved optical spectroscopies, electron microscopy, cyclic voltammetry, and density functional theory simulations, we elucidate the atomic-scale mechanism behind PIERS. Stable PIERS substrates were fabricated using self-organized arrays of TiO2 nanotubes with controlled oxygen vacancy doping and size-controlled silver nanoparticles. The key source of PIERS vs SERS enhancement is an increase in the Raman polarizability of the adsorbed analyte upon photoinduced charge transfer. A balance between improved crystallinity, which enhances charge transfer due to higher electron mobility but decreases light absorption, and increased oxygen vacancy defect concentration, which increases light absorption, is critical. This work enables the rational design of PIERS substrates for sensing.

The Effects of Interacting With a Paro Robot After a Stressor in Patients With Psoriasis: A Randomised Pilot Study.

Objective: Stress can play a role in the onset and exacerbation of psoriasis. Psychological interventions to reduce stress have been shown to improve psychological and psoriasis-related outcomes. This pilot randomised study investigated the feasibility of a brief interaction with a Paro robot to reduce stress and improve skin parameters, after a stressor, in patients with psoriasis. Methods: Around 25 patients with psoriasis participated in a laboratory stress task, before being randomised to either interact with a Paro robot or sit quietly (control condition) for 30 min. Raman spectroscopy and trans-epidermal water loss were measured at baseline, after the stressor and after the intervention as indexes of acute skin changes. Psychological variables, including self-reported stress and affect, were also measured at the three time-points. Results: No statistically significant differences between the two conditions were found for any of the outcomes measured. However, effect sizes suggest significance could be possible with a larger sample size. Changes in the psychological and Raman spectroscopy outcomes across the experimental session were found, indicating the feasibility of the procedures. Conclusion: This pilot study showed that a brief interaction with a Paro robot was a feasible intervention for patients with psoriasis, but future trials should broaden the inclusion criteria to try to increase recruitment rates. Studying people who are highly stressed, depressed or who are stress-responders may increase the power of the intervention to show effects using a longer-term intervention.

Detecting Phytoplankton Cell Viability Using NIR Raman Spectroscopy and PCA.

Raman spectroscopy has long been suggested as a potentially fast and sensitive method to monitor phytoplankton abundance and composition in marine environments. However, the pitfalls of visible detection methods in pigment-rich biological material and the complexity of their spectra have hindered their application as reliable in situ detection methods. In this study we combine 1064 nm confocal Raman spectroscopy with multivariate statistical analysis techniques (principle component analysis and partial leas-squares discriminant analysis) to reliably measure differences in the cell viability of a diatom species (Chaetoceros muelleri) and two haptophyte species (Diacronema lutheri and Tisochrysis lutea) of phytoplankton. The low fluorescence background due to this combined approach of NIR Raman spectroscopy and multivariate data analysis allowed small changes in the overall spectral profiles to be reliably monitored, enabling the identification of the specific spectral features that could classify cells as viable or nonviable regardless of their species. The most significant differences upon cell death were shown by characteristic shifts in the carotenoid bands at 1527 and 1158 cm-1. The contributions from other biomolecules were less pronounced but revealed changes that could be identified using this combination of techniques.

Exploiting hydrogen bonding to enhance lidocaine loading and stability in a poly ethylene-co-vinyl acetate carrier matrix.

Sustained release of lidocaine from poly ethylene-co-vinyl acetate (EVA) implants can significantly improve pain management outcomes; however, poor drug loading is a major limitation. Recently, myristic acid was found to improve drug loading in EVA by inhibiting the crystallization of lidocaine. Here, lidocaine's interaction with myristic acid was studied by differential scanning calorimetry. Spectra of lidocaine-myristic acid mixtures were analysed using two-dimensional correlation (2DCOS) maps. Furthermore, spectroscopic analysis of EVA matrices containing lidocaine, alone and in combination with myristic acid, was also performed and drug release was evaluated in vitro. A eutectic was obtained on combining lidocaine and myristic acid at the molar ratio of 1:1 due to loss of myristic acid's dimeric conformation resulting in hydrogen bonding of its COOH group with lidocaine's amide I moieties. In EVA, hydrogen bonding between adjacent lidocaine molecules caused crystallization above a threshold concentration and could be inhibited by incorporation of myristic acid by eutectic formation. By altering the molecular confirmation and solid state properties of lidocaine in EVA, myristic acid reduces lidocaine crystallization, increases drug loading and influences drug release kinetics. Exploiting these interactions and promoting further hydrogen bonding through the addition of specific excipients presents a viable strategy to enhance and stabilise drug loading in polymer matrices for various applications.

Ingestion of microplastics and mesoplastics by Trachurus declivis (Jenyns, 1841) retrieved from the food of the Australasian gannet Morus serrator: First documented report from New Zealand.

During the process of studying some morphological characters of fish found in the food of the Australasian gannet Morus serrator breeding at Horuhoru Rock and Mahuki islands in the Hauraki Gulf, New Zealand, one carangid specimen of fish species Trachurus declivis out of the 25 fish specimens examined revealed seven small plastic particles in its stomach of different colours: black, red, blue, green, and transparent. Fourier transform infrared (FTIR) spectroscopy was used to identify the compositions of the particles as low and high density polyethylene, poly (methyl methacrylate), polypropylene, and a copolymer of butadiene, acrylonitrile, and methacrylamide. The plastic particles comprised several different shapes and sizes, ranging between 4.5 and 10 mm, and are therefore categorized as micro-and mesoplastic fragments.

Routine Monitoring of Instrument Stability in a Milk Testing Laboratory With ASCA: A Pilot Study.

Mid-infrared spectroscopy has been developed as a reliable and rapid tool for routine analysis of fat, protein, lactose and other components in liquid milk. However, variations within and between FTIR instruments, even within the same milk testing laboratory, present a challenge to the accuracy of measurement of particularly minor components in the milk, such as individual fatty acids or proteins. In this study we have used Analysis of variance-Simultaneous Component Analysis (ASCA), to monitor the spectral variation between and within each of four different FOSS FTIR spectrometers over each week in an independent milk testing laboratory over 4 years, between August 2017 and March 2021 (223 weeks). On everyday of each week, spectra of the same pilot milk sample were recorded approximately every hour on each of the four instruments. Overall, variations between instruments had the largest effect on spectral variation over each week, making a significant contribution every week. Within each instrument, day-to-day variations over the week were also significant for all but two of the weeks measured, however it contributed less to the variance overall. At certain times other factors not explained by weekday variation or inter-instrument variation dominated the variance in the spectra. Examination of the scores and loadings of the weekly ASCA analysis allowed identification of changes in the spectral regions affected by drifts in each instrument over time. This was found to particularly affect some of the fatty acid predictions.

Electrochemical preparation of pore wall modification gradients across thin porous silicon layers.

Thin film porous silicon layers have been constructed in which the level of chemical modification to the pore walls is altered in a controlled gradient across the material. The gradient modification within such a nanoporous material represents a significant advance over gradients imposed across a flat surface. Gradients of methyl, pentyl acetate, and decyl groups are formed via electrochemical attachment of organohalides with an asymmetric electrode arrangement. The stability and hydrophobicity of the latter two systems have been improved through postprocess "end-capping" of the porous silicon with methyl groups. Two-dimensional mapping transmission FTIR microspectrophotometry and ATR-FTIR have been employed to characterize these new materials. Cleaving the surface-attached pentyl acetate groups to 5-hydroxypentyl groups leads to materials that can act as efficient visual indicators of the ethanol concentration in water over the range 1-10 vol %.

Raman spectroscopy reveals age- and sex-related differences in cortical bone from people with osteoarthritis.

Bone strength in human cortical bone is determined by the composition and structure of both the mineral and collagen matrices and influenced by factors such as age, gender, health, lifestyle and genetic factors. Age-related changes in the bone matrix are known to result in loss of mechanical strength and increased fragility. In this study we show how Raman spectroscopy, with its exquisite sensitivity to the molecular structure of bone, reveals new insights into age- and sex-related differences. Raman analysis of 18 samples of cortical hip bone obtained from people aged between 47-82 years with osteoarthritis (OA) found subtle changes in the lipid and collagen secondary structure, and the carbonate (CO32-) and phosphate (PO43-) mineral ratios in the bone matrix. Significant differences were observed between older and younger bones, and between older female and older male bones; no significant differences were observed between younger male and female bones. Older female bones presented the lowest mineral to matrix ratios (MMR) and highest CO32-/PO43- ratios, and relative to lipid/collagen -CH2 deformation modes at 1450 cm-1 they had lowest overall mineral content, higher collagen cross linking and lipid content but lower levels of α-helix collagen structures than older male and younger male and female bones. These observations provided further insight on bone composition changes observed in the bone volume fraction (BV/TV) for the older female bones from microCT measurements on the same samples, while tissue mineral density (TMD) measurements had shown no significant differences between the samples.

Correction: Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein-Ru(carbene) adduct.

Correction for 'Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein-Ru(carbene) adduct' by Matthew P. Sullivan et al., Chem. Commun., 2018, 54, 6120-6123.

Using near infrared spectroscopy to predict the lignin content and monosaccharide compositions of Pinus radiata wood cell walls.

Near infrared (NIR) spectroscopy coupled with partial least squares (PLS-1) regression was used to predict the lignin contents and monosaccharide compositions of milled wood of Pinus radiata. The effects of particle size and moisture content were investigated by collecting NIR spectra of four sample types: large (<0.422mm) and small (<0.178mm) particles, in both ambient and dry conditions. PLS-1 models were constructed using mixtures of compression wood (CW) and opposite wood (OW) that provided a linear range of cell-wall compositions. Our results show that lignin contents and monosaccharide compositions of pure CWs and OWs can be successfully predicted using NIR spectra of all four sample types. However, large particles in ambient conditions have the most efficient preparation and the standard error (SE) values for lignin (2.10%), arabinose (0.34%), xylose (1.33%), galactose (2.54%), glucose (6.98%), mannose (1.48%), galacturonic acid (0.22%), glucuronic acid (0.06%), and 4-O-methylglucuronic acid (0.25%) were achieved.

The antimicrobial action of polyaniline involves production of oxidative stress while functionalisation of polyaniline introduces additional mechanisms.

Polyaniline (PANI) and functionalised polyanilines (fPANI) are novel antimicrobial agents whose mechanism of action was investigated. Escherichia coli single gene deletion mutants revealed that the antimicrobial mechanism of PANI likely involves production of hydrogen peroxide while homopolymer poly(3-aminobenzoic acid), P3ABA, used as an example of a fPANI, disrupts metabolic and respiratory machinery, by targeting ATP synthase and causes acid stress. PANI was more active against E. coli in aerobic, compared to anaerobic, conditions, while this was apparent for P3ABA only in rich media. Greater activity in aerobic conditions suggests involvement of reactive oxygen species. P3ABA treatment causes an increase in intracellular free iron, which is linked to perturbation of metabolic enzymes and could promote reactive oxygen species production. Addition of exogenous catalase protected E. coli from PANI antimicrobial action; however, this was not apparent for P3ABA treated cells. The results presented suggest that PANI induces production of hydrogen peroxide, which can promote formation of hydroxyl radicals causing biomolecule damage and potentially cell death. P3ABA is thought to act as an uncoupler by targeting ATP synthase resulting in a futile cycle, which precipitates dysregulation of iron homeostasis, oxidative stress, acid stress, and potentially the fatal loss of proton motive force.

Pentachlorophenol dechlorination with zero valent iron: a Raman and GCMS study of the complex role of surficial iron oxides.

The dechlorination of chlorinated organic pollutants by zero valent iron (ZVI) is an important water treatment process with a complex dependence on many variables. This complexity means that there are reported inconsistencies in terms of dechlorination with ZVI and the effect of ZVI acid treatment, which are significant and are as yet unexplained. This study aims to decipher some of this complexity by combining Raman spectroscopy with gas chromatography-mass spectrometry (GC-MS) to investigate the influence of the mineralogy of the iron oxide phases on the surface of ZVI on the reductive dechlorination of pentachlorophenol (PCP). Two electrolytic iron samples (ZVI-T and ZVI-H) were found to have quite different PCP dechlorination reactivity in batch reactors under anoxic conditions. Raman analysis of the "as-received" ZVI-T indicated the iron was mainly covered with the ferrous oxide (FeO) wustite, which is non-conducting and led to a low rate of PCP dechlorination. In contrast, the dominant oxide on the "as-received" ZVI-H was magnetite which is conducting and, compared to ZVI-T, the ZVI-H rate of PCP dechlorination was four times faster. Treating the ZVI-H sample with 1 N H2SO4 made small change to the composition of the oxide layers and also minute change to the rate of PCP dechlorination. However, treating the ZVI-T sample with H2SO4 led to the loss of wustite so that magnetite became the dominant oxide and the rate of PCP dechlorination increased to that of the ZVI-H material. In conclusion, this study clearly shows that iron oxide mineralogy can be a contributing factor to apparent inconsistencies in the literature related to ZVI performance towards dechlorination and the effect of acid treatment on ZVI reactivity.

Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein-Ru(carbene) adduct.

The first X-ray structures of adducts formed between a RuII(N-heterocyclic carbene)(η6-p-cymene) compound and a protein are reported. Coordination to the protein induced the cleavage of the cymene ligand and EPR spectroscopy demonstrated the oxidation of the Ru centre.