Formic Acid, a Ubiquitous but Overlooked Component of the Early Earth Atmosphere.

Terrestrial volcanism has been one of the dominant geological forces shaping our planet since its earliest existence. Its associated phenomena, like atmospheric lightning and hydrothermal activity, provide a rich energy reservoir for chemical syntheses. Based on our laboratory simulations, we propose that on the early Earth volcanic activity inevitably led to a remarkable production of formic acid through various independent reaction channels. Large-scale availability of atmospheric formic acid supports the idea of the high-temperature accumulation of formamide in this primordial environment.

Perspectives of DCDR-GERS in the analysis of amino acids.

Graphene-enhanced Raman scattering (GERS) has attracted increasing attention from many scientists in recent years as a novel and potentially strong analytical technique since its discovery in 2010. GERS combines the ultra-high sensitivity and spectral analysis of the structural properties of many molecules found in surface-enhanced Raman scattering (SERS) and graphene simple sample processing and excellent uniformity. This facilitates a fast and very sensitive analysis of a wide range of analytes. Here, we present a new method for amino acid analysis based on the combination of drop coating deposition Raman (DCDR) and GERS. The potential of the method was evaluated in the analyses of Trp, Leu, Phe, and DOPA. Achievable limits of detection for all the studied amino acids are in tens of ng mL-1.

Imaging of growth factors on a human tooth root canal by surface-enhanced Raman spectroscopy.

Endodontic treatment of immature permanent teeth with necrotic pulp poses several clinical challenges and is one of the most demanding interventions in endodontics. Recently, with new discoveries in the field of tissue engineering, novel treatment protocols have been established. The most promising treatment modality is revascularization, whose integral part is the exposure of collagen matrix and embedded growth factors. However, optimization of the treatment protocol requires a development of analytical procedures able to analyze growth factors directly on the sample surface. In this work, method based on surface-enhanced Raman spectroscopy (SERS) was developed to investigate the influence of the time of the medical treatment using EDTA on exposure and accessibility of the growth factors, namely TGF-ß1, BMP-2, and bFGF on the dentine surface. The nanotags, which consist of magnetic Fe3O4@Ag nanocomposite covalently functionalized by tagged antibodies (anti-TGF-ß1-Cy3, anti-BMP-2-Cy5, and anti-bFGF-Cy7), were employed as a SERS substrate. Each antibody was coupled with a unique label allowing us to perform a parallel analysis of all three growth factors within one analytical run. Developed methodology presents an interesting alternative to a fluorescence microscopy and in contrary allows evaluating a chemical composition and thus minimizing possible false-positive results. Graphical abstract.

Detection of Prosthetic Joint Infection Based on Magnetically Assisted Surface Enhanced Raman Spectroscopy.

Accurate and rapid diagnosis of prosthetic joint infection (PJI) is vital for rational and effective therapeutic management of this condition. Several diagnostic strategies have been developed for discriminating between infected and noninfected cases. However, none of them can reliably diagnose the whole spectrum of clinical presentations of PJI. Here, we report a new method for PJI detection based on magnetically assisted surface enhanced Raman spectroscopy (MA-SERS) using streptavidin-modified magnetic nanoparticles (MNP@Strep) whose surface is functionalized with suitable biotinylated antibodies and then coated with silver nanoparticles by self-assembly. The high efficiency of this approach is demonstrated by the diagnosis of infections caused by two bacterial species commonly associated with PJI, namely, Staphylococcus aureus and Streptococcus pyogenes. The method's performance was verified with model samples of bacterial lysates and with four real-matrix samples of knee joint fluid spiked with live pathogenic bacterial cells. This procedure is operationally simple, versatile, inexpensive, and quick to perform, making it a potentially attractive alternative to established diagnostic techniques based on Koch's culturing or colony counting methods.

Nonenzymatic Oligomerization of 3',5'-Cyclic CMP Induced by Proton and UV Irradiation Hints at a Nonfastidious Origin of RNA.

We report that 3',5'-cyclic CMP undergoes nonenzymatic di- and trimerization at 20 °C under dry conditions upon proton or UV irradiation. The reaction involves stacking of the cyclic monomers and subsequent polymerization through serial transphosphorylations between the stacked monomers. Proton- and UV-induced oligomerization of 3',5'-cyclic CMP demonstrates that pyrimidines-similar to purines-might also have taken part in the spontaneous generation of RNA under plausible prebiotic conditions as well as in an extraterrestrial context. The observed polymerization of naturally occurring 3',5'-cyclic nucleotides supports the possibility that the extant genetic nucleic acids might have originated by way of a straight Occamian path, starting from simple reactions between plausibly preactivated monomers.

Pd@Pt Core-Shell Nanoparticles with Branched Dandelion-like Morphology as Highly Efficient Catalysts for Olefin Reduction.

A facile synthesis based on the addition of ascorbic acid to a mixture of Na2 PdCl4, K2 PtCl6, and Pluronic P123 results in highly branched core-shell nanoparticles (NPs) with a micro-mesoporous dandelion-like morphology comprising Pd core and Pt shell. The slow reduction kinetics associated with the use of ascorbic acid as a weak reductant and suitable Pd/Pt atomic ratio (1:1) play a principal role in the formation mechanism of such branched Pd@Pt core-shell NPs, which differs from the traditional seed-mediated growth. The catalyst efficiently achieves the reduction of a variety of olefins in good to excellent yields. Importantly, higher catalytic efficiency of dandelion-like Pd@Pt core-shell NPs was observed for the olefin reduction than commercially available Pt black, Pd NPs, and physically admixed Pt black and Pd NPs. This superior catalytic behavior is not only due to larger surface area and synergistic effects but also to the unique micro-mesoporous structure with significant contribution of mesopores with sizes of several tens of nanometers.

Colloidal Surface Active Maghemite Nanoparticles for Biologically Safe Cr(VI) Remediation: from Core-Shell Nanostructures to Pilot Plant Development.

The present study is aimed at the exploration of achievable improvements for Cr(VI) ex situ and in situ water remediation by using novel naked colloidal maghemite (γ-Fe2 O3 ) nanoparticles (surface active maghemite nanoparticles, SAMNs). The reliability of SAMNs for Cr(VI) binding and removal was demonstrated, and SAMN@Cr(VI) complex was characterized, as well as the covalent nature of the absorption was unequivocally proved. SAMNs were structurally and magnetically well conserved after Cr(VI) binding. Thus, in consideration of their affinity for Cr(VI) , SAMNs were exploited in a biological model system, mimicking a real in situ application. The assay evidenced a progressive reduction of revertant colonies of Salmonella typhimurium TA100 strain, as maghemite nanoparticles concentration increased, till the complete suppression of Cr(VI) mutagen effect. Finally, an automatic modular pilot system for continuous magnetic removal and recovery of Cr(VI) from water is proposed. SAMNs, thanks to their colloidal, binding, and catalytic properties, represent a promising tool as a reliable nanomaterial for water remediation by Cr(VI) .

Study of phenolic profile and antioxidant activity in selected Moravian wines during winemaking process by FT-IR spectroscopy.

Wine belongs to a family of products where the quality matters. Its quality can be in principle verified using diverse physicochemical approaches, including the determination of various chemical compounds generally accepted as chemical markers of product quality. Example of such applicable compounds is a family derived from phenols. Next to a more classical approach, infrared spectroscopy can play an important role in this game. Here we sought to develop an easy to use, ultra-fast and robust method based on FT-IR with some important advantages including lower sample and solvent consumptions. The tested and evaluated method was consequently applied in a monitoring of changes in a content of total phenolic compounds (TPC) and total antioxidant activity (TAA) during a process of wine-making. It was found out that total amount of phenolic compounds differs both for individual kind of wines, namely red, white and rose, at each processing stage of the production. The content of phenolic compounds of red and white wine increased while an opposite trend was observed in rose wine. TAA values of analysed wines showed difference between individual kind of wine and indicate the same trend like phenolic profile. Antioxidant activity values relate to changes of phenolic content during production process.

Magnetically-assisted surface enhanced raman spectroscopy (MA-SERS) for label-free determination of human immunoglobulin G (IgG) in blood using Fe3O4@Ag nanocomposite.

Development of methods allowing determination of even ultralow levels of immunoglobulins in various clinical samples including whole human blood and plasma is a particular scientific challenge, especially due to many essential discoveries in the fields of immunology and medicine in the past few decades. The determination of IgG is usually performed using an enzymatic approach, followed by colorimetric or fluorimetric detection. However, limitations of these methods relate to their complicated setup and stringent requirements concerning the sample purity. Here, we present a novel approach based on magnetically assisted surface enhanced Raman spectroscopy (MA/SERS), which utilizes a Fe3O4@Ag@streptavidin@anti-IgG nanocomposite with strong magnetic properties and an efficient SERS enhancement factor conferred by the Fe3O4 particles and silver nanoparticles, respectively. Such a nanocomposite offers the possibility of separating a target efficiently from a complex matrix by simple application of an external magnetic force, followed by direct determination using SERS. High selectivity was achieved by the presence of anti-IgG on the surface of silver nanoparticles coupled with their further inactivation by ethylamine. Compared to many recently developed sandwich methods, application of single nanocomposites showed many advantages, including simplicity of use, direct control of the analytic process, and elimination of errors caused by possible nonspecific interactions. Moreover, incorporation of advanced spectral processing methods led to a considerable decrease in the relative error of determination to below 5%.

Magnetically assisted surface-enhanced raman scattering selective determination of dopamine in an artificial cerebrospinal fluid and a mouse striatum using Fe(3)O(4)/Ag nanocomposite.

The dopaminergic neural system is a crucial part of the brain responsible for many of its functions including mood, arousal, and other roles. Dopamine is the key neurotransmitter of this system, and a determination of its level presents a demanding task needed for a deeper understanding of the processes, even pathological, involving this brain part. In this work, we present a method for a fast analysis of dopamine levels in samples of cerebrospinal fluid and mouse striatum. The method is based on a nanocomposite composed of magnetite and silver nanoparticles, whose surface is modified with iron nitriloacetic acid (Fe-NTA)-a dopamine-selective compound. The magnetic properties of this nanocomposite enable simple separation of targeted molecules from a complex matrix while the silver acts as a platform for surface-enhanced Raman scattering (SERS). Silver and magnetite nanoparticles are joined by carboxymethyl chitosan, useful in biological environments and enhancing the sensitivity due to the presence of carboxyl groups. This system reveals a good stability and reproducibility. Moreover, rapid and simple quantitative experiments show an improvement in the detection of dopamine levels in biological assays at low femtomolar concentrations. The comparative data performed with clinical samples of mouse striatum show that the developed magnetic SERS is a strong alternative to conventional high-performance liquid chromatography-mass spectrometry (HPLC-MS) with even several superior aspects including faster and cheaper analysis and no necessity of sample preconcentration or derivatization.

Discrimination of circulating tumor cells of breast cancer and colorectal cancer from normal human mononuclear cells using Raman spectroscopy.

Circulating tumor cells present an important marker of the progress of several cancer diseases including breast and colorectal cancer, and enables an interesting prognosis and diagnostic options that can complement convenient diagnostic techniques based on several imaging methods. Based on its relevance, the analysis of such kinds of cells is within the scope of many research and clinical institutes; however, it still presents a difficult task. Here we used a state-of-the-art micro-Raman microscopic technique to enhance possibilities in the study of circulating tumor cells and their further differentiation. As cytospins present a convenient form of sample collection and preparation, we used this form of sampling as the initial point. Raman presents a non-destructive form of sample analysis and thus the samples can be further used for a method validation. We have considered the influence of fixation methods of the cells, where we found out that the ability of Raman spectroscopy to differentiate between three cell lines strictly depends upon the sample preparation method used. Namely breast (BT 549) and colorectal (HCT 116) circulating tumor cell lines and human mononuclear cells were compared. Methanol and paraformaldehyde methods of fixation were compared to simple drying out of the sample. It has been shown that drying out of the cells enables the best performance to be obtained in cell differentiation and this is demonstrated by the use of principal component analysis, where all three given cell lines were differentiated with a high level of confidence. Next, the cells were also scanned using 1 µm spatial resolution. The acquired data were visualized using both chemigrams and hierarchical clustering analysis.

Highly Cytotoxic Copper(II) Mixed-Ligand Quinolinonato Complexes: Pharmacokinetic Properties and Interactions with Drug Metabolizing Cytochromes P450.

The effects of two anticancer active copper(II) mixed-ligand complexes of the type [Cu(qui)(mphen)]Y·H2O, where Hqui = 2-phenyl-3-hydroxy- 1H-quinolin-4-one, mphen = bathophenanthroline, and Y = NO3 (complex 1) or BF4 (complex 2) on the activities of different isoenzymes of cytochrome P450 (CYP) have been evaluated. The screening revealed significant inhibitory effects of the complexes on CYP3A4/5 (IC50 values were 2.46 and 4.88 µM), CYP2C9 (IC50 values were 16.34 and 37.25 µM), and CYP2C19 (IC50 values were 61.21 and 77.07 µM). Further, the analysis of mechanisms of action uncovered a non-competitive type of inhibition for both the studied compounds. Consequent studies of pharmacokinetic properties proved good stability of both the complexes in phosphate buffer saline (>96% stability) and human plasma (>91% stability) after 2 h of incubation. Both compounds are moderately metabolised by human liver microsomes (<30% after 1 h of incubation), and over 90% of the complexes bind to plasma proteins. The obtained results showed the potential of complexes 1 and 2 to interact with major metabolic pathways of drugs and, as a consequence of this finding, their apparent incompatibility in combination therapy with most chemotherapeutic agents.

On-line preconcentration of perfluorooctanoic acid and perfluorooctanesulfonic acid by nonaqueous capillary electrophoresis.

Separation of major environmental pollutants as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) by capillary electrophoresis is reported for the first time. It is not possible to resolve the solutes in an aqueous media. However, the use of methanol and acetonitrile as the background electrolyte (BGE) solvents allowed their rapid separation in an uncoated capillary. A major effort was put into BGE optimization in respect to both separation efficiency and detection for further on-line preconcentration. 5 mmol.L⁻¹ naphthalene-1-sulfonic acid and 10 mmol.L⁻¹ triethylamine dissolved in ACN/MeOH (50:50 v/v) provided best separation and detection conditions. Next, the large-volume sample stacking and the field-amplified sample injection were applied and compared. Large-volume sample stacking improved limits of detection (LODs) with regard to the standard injection by 69 times for PFOA and 143 times for PFOS with LODs of 280 and 230 nmol.L⁻¹, respectively. Field-amplified sample injection improved LODs 624 times for PFOAand 806 times for PFOS with LODs 31 and 40 nmol.L⁻¹, respectively. Both preconcentration methods showed repeatabilities of migration times less than 1.2% RSD intraday and 6.6% RSD interday. The method was applied on PFOA and PFOS analysis in a sample of river water treated with solid-phase extraction, which further improved LOD toward 5.6 × 10⁻¹° mol.L⁻¹ for PFOS and 6.4 × 10⁻¹° mol.L⁻¹ for PFOA and allows the method to be used for river water contamination screening or decomposition studies.

Reproducible discrimination between gram-positive and gram-negative bacteria using surface enhanced Raman spectroscopy with infrared excitation.

The on time diagnostics of bacterial diseases is one of the essential steps in the foregoing treatment of such pathogens. Here we sought to present an easy to use and robust method for the discrimination between Gram-positive (Enterococcus faecalis and Streptococcus pyogenes) and Gram-negative (Acinetobacter baumannii and Klebsiella pneumoniae) bacterial genera based on surface enhanced Raman scattering (SERS) spectroscopy. The robustness of our approach lies in the novel method for the production of the SER substrate based on silver nanoparticles and their subsequent re-crystallization in solutions containing high concentrations of chloride ions. The method presented here could be an interesting alternative both to commonly used histochemical approaches and commercial SERS substrates.

Graphene Oxide Nanoplatforms to Enhance Cisplatin-Based Drug Delivery in Anticancer Therapy.

Chemotherapeutics such as platinum-based drugs are commonly used to treat several cancer types, but unfortunately, their use is limited by several side effects, such as high degradation of the drug before entering the cells, off-target organ toxicity and development of drug resistance. An interesting strategy to overcome such limitations is the development of nanocarriers that could enhance cellular accumulation in target cells in addition to decreasing associated drug toxicity in normal cells. Here, we aim to prepare and characterize a graphene-oxide-based 2D nanoplatform functionalised using highly branched, eight-arm polyethylene-glycol, which, owing to its high number of available functional groups, offers considerable loading capacity over its linear modalities and represents a highly potent nanodelivery platform as a versatile system in cancer therapy. The obtained results show that the GO@PEG carrier allows for the use of lower amounts of Pt drug compared to a Pt-free complex while achieving similar effects. The nanoplatform accomplishes very good cellular proliferation inhibition in osteosarcoma, which is strictly related to increased cellular uptake. This enhanced cellular internalization is also observed in glioblastoma, although it is less pronounced due to differences in metabolism compared to osteosarcoma. The proposed GO@PEG nanoplatform is also promising for the inhibition of migration, especially in highly invasive breast carcinoma (i.e., MDA-MB-231 cell line), neutralizing the metastatic process. The GO@PEG nanoplatform thus represents an interesting tool in cancer treatment that can be specifically tailored to target different cancers.

Determination of rosiglitazone and metformin in human serum by CE-ESI-MS.

A new method for the determination of anti-diabetic drugs metformin and rosiglitazone based on the use of capillary electrophoresis with electrospray mass spectrometry was developed. The proposed method allowed their separation within 11 min by using 50 mM formic acid at +20 kV. Positive electrospray ionization and selected ion monitoring [M+H](+) of metformin (m/z=130) and rosiglitazone (m/z=358) were performed. Several important experimental parameters influencing electrospray ionization of metformin and rosiglitazone were studied. The final composition of sheath liquid was water/methanol/formic acid (50:49.5:0.5, v/v/v), at a flow rate of 2 µL/min. The developed method was applied for the determination of metformin and rosiglitazone simultaneously in human serum after protein precipitation with acetonitrile. The limits of detection of developed method were 4.42 and 2.14 ng/mL for rosiglitazone and for metformin, respectively, which is sufficient for therapeutic serum concentration levels monitoring for both studied drugs.

Covalent Graphene-MOF Hybrids for High-Performance Asymmetric Supercapacitors.

In this work, the covalent attachment of an amine functionalized metal-organic framework (UiO-66-NH2  = Zr6 O4 (OH)4 (bdc-NH2 )6 ; bdc-NH2  = 2-amino-1,4-benzenedicarboxylate) (UiO-Universitetet i Oslo) to the basal-plane of carboxylate functionalized graphene (graphene acid = GA) via amide bonds is reported. The resultant GA@UiO-66-NH2 hybrid displayed a large specific surface area, hierarchical pores and an interconnected conductive network. The electrochemical characterizations demonstrated that the hybrid GA@UiO-66-NH2 acts as an effective charge storing material with a capacitance of up to 651 F g-1 , significantly higher than traditional graphene-based materials. The results suggest that the amide linkage plays a key role in the formation of a π-conjugated structure, which facilitates charge transfer and consequently offers good capacitance and cycling stability. Furthermore, to realize the practical feasibility, an asymmetric supercapacitor using a GA@UiO-66-NH2 positive electrode with Ti3 C2 TX MXene as the opposing electrode has been constructed. The cell is able to deliver a power density of up to 16 kW kg-1 and an energy density of up to 73 Wh kg-1 , which are comparable to several commercial devices such as Pb-acid and Ni/MH batteries. Under an intermediate level of loading, the device retained 88% of its initial capacitance after 10 000 cycles.

Analysis of buserelin in urine by online combination of capillary zone electrophoresis with electrospray mass spectrometry.

A fast and precise analysis of the synthetic peptide buserelin in urine using CZE-ESI-MS method has been demonstrated. Formic acid at 50 mmol/L concentration served as background electrolyte in CZE stage and it is compatible with MS detection in positive ionization mode. Two injection modes were tested, i.e. pressure (50 mbar for 5 s) and electrokinetic injection (5 kV for 5 s), of which electrokinetic injection provided better calibration parameters. Buserelin LODs were 0.47 microg/mL in water and 0.63 microg/mL in ten times diluted urine samples using pressure injection, while they were 0.32 microg/mL in water and 0.34 microg/mL in ten times diluted urine samples using electrokinetic injection. Repeatability of buserelin migration times was below 6% (pressure injection mode) and 1% (electrokinetic injection mode). Repeatability of buserelin peak area in SIM mode (m/z=620.5+/-0.5) was less than 12% (pressure injection mode) and 5.8% (electrokinetic injection mode). In this work, no interferences were observed during the analyses of spiked urine samples.

Chiral discrimination of amino acids using phosphorene assisted graphene-enhanced Raman spectroscopy.

Discrimination of enantiomers poses a scientific challenge as the chemical and physical properties of enantiomers are nearly identical. The chiral analysis is usually performed by separation techniques, including chromatography, electrophoresis, or optical instrumentation based on an interaction of the analyzed sample with a polarized beam of light. Here we present a novel method for a chiral screening based on a combination of the black phosphorus@Graphene nanocomposite and Raman spectroscopy. The nanocomposite allows to enhance the Raman signal with factors higher than 100 asymmetrically and provide altered signals for mixtures containing varying enantiomeric ratios of target compounds. Tryptophan, Phenylalanine, DOPA, Isoleucine, and Leucine were selected as model compounds; the method allows us to discriminate between mixtures with 10, 25, 50, 75, and 100% enantiomeric purity.

New Limits for Stability of Supercapacitor Electrode Material Based on Graphene Derivative.

Supercapacitors offer a promising alternative to batteries, especially due to their excellent power density and fast charging rate capability. However, the cycling stability and material synthesis reproducibility need to be significantly improved to enhance the reliability and durability of supercapacitors in practical applications. Graphene acid (GA) is a conductive graphene derivative dispersible in water that can be prepared on a large scale from fluorographene. Here, we report a synthesis protocol with high reproducibility for preparing GA. The charging/discharging rate stability and cycling stability of GA were tested in a two-electrode cell with a sulfuric acid electrolyte. The rate stability test revealed that GA could be repeatedly measured at current densities ranging from 1 to 20 A g-1 without any capacitance loss. The cycling stability experiment showed that even after 60,000 cycles, the material kept 95.3% of its specific capacitance at a high current density of 3 A g-1. The findings suggested that covalent graphene derivatives are lightweight electrode materials suitable for developing supercapacitors with extremely high durability.