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Thirty-five years ago, Professors Rudolf Kaiser and Szabolcs Nyiredy launched the “Journal for Planar Chromatography – Modern TLC,” better known as JPC. Later, on the occasion of JPC’s first 20 years, Prof. Kaiser made a parallel between this beautiful age of the human being and the development of the journal. In his editorial, he highlighted that high-performance thin-layer chromatography (HPTLC) was the most appropriate technique for cases in which the complexity of mixtures is too critical for classical column separations, and that it was the best analytical technique for optimizing production, because it can be simple, performed quickly, and very economical, without forgetting that it always uses a clean stationary phase free from memory effects. Likewise, he highlighted the important advances in pharmaceutical quality control, for environmental analysis, and for analysis of many highly complicated natural products.

Thlaspi arvense (Pennycress) is an emerging feedstock for biofuel production because of its high seed oil content enriched in erucic acid. A transcriptomic and a lipidomic study were performed to analyze the dynamics of gene expression, glycerolipid content and acyl-group distribution during seed maturation. Genes involved in fatty acid biosynthesis were expressed at the early stages of seed maturation. Genes encoding enzymes of the Kennedy pathway like diacylglycerol acyltransferase1 (TaDGAT1), lysophosphatidic acid acyltransferase (TaLPAT) or glycerol 3-phosphate acyltransferase (TaGPAT) increased their expression with maturation, coinciding with the increase in triacylglycerol species containing 22:1. Positional analysis showed that the most abundant triacylglycerol species contained 18:2 at sn-2 position in all maturation stages, suggesting no specificity of the lysophosphatidic acid acyltransferase for very long chain fatty acids. Diacylglycerol acyltransferase2 (TaDGAT2) mRNA was more abundant at the initial maturation stages, coincident with the rapid incorporation of 22:1 to triacylglycerol, suggesting a coordination between Diacylglycerol acyltransferase enzymes for triacylglycerol biosynthesis. Genes encoding the phospholipid-diacylglycerol acyltransferase (TaPDAT1), lysophosphatidylcholine acyltransferase (TaLPCAT) or phosphatidylcholine diacylglycerolcholine phosphotransferase (TaPDCT), involved in acyl-editing or phosphatidyl-choline (PC)-derived diacylglycerol (DAG) biosynthesis showed also higher expression at the early maturation stages, coinciding with a higher proportion of triacylglycerol containing C18 fatty acids. These results suggested a higher contribution of these two pathways at the early stages of seed maturation. Lipidomic analysis of the content and acyl-group distribution of diacylglycerol and phosphatidyl-choline pools was compatible with the acyl content in triacylglycerol at the different maturation stages. Our data point to a model

Classic saturates, aromatics, resins, and asphaltenes (SARA) analysis has long enabled the chromatographic separation of complex hydrocarbon-containing products into these four families. This simplification often does not provide sufficient or correct information on the relationship between the composition of the products and the process variables studied. The obtention of profiles by gradient automated multiple development (AMD) is an interesting alternative to obtain extended SARA separations with increasing level of complexity for heavy petroleum products that adequately represent the entirety of the sample. An optimized 20-step gradient based on tetrahydrofuran (THF)‒dichloromethane‒n-heptane over a total migration distance of 83 mm is proposed here to characterize all types of heavy oil products. The combination of ultraviolet (UV)–densitometry (at 201, 228, and 273 nm), fluorescence detection by intensity changes using berberine cation, together with on-plate recording of UV spectra of separated peaks and the comparison with those of standards, allow for a deep characterization of chemical families. In the apolar zone of the chromatogram saturates, naphthenes, naphteno-aromatics, alkyl-aromatics, and aromatics with different degrees of condensation are detected. The use of THF, both in the plate precleaning stage and in the first stages of the gradient, is responsible for the satisfactory resolution of the resins in the polar zone. AMD chromatographic zones can be related to peaks from hydrocarbon groups in classical SARA. The application of this gradient to different types of products allowed for the relation of the profiles of bitumen to their origin, differentiation of the resin part trapped in asphaltenes, control performance of deasphalting in hydrorefining products, and the control of the composition of base oils.

Section S1: Quantification of Au(III) immobilized in tectomer by means of AuBr4− complex formation. (Table S1: Effect of the pH on AuBr4− complex formation. Figure S1: (a) Absorption spectra of AuBr4−; (b) Absorption spectra upon addition of KBr to a solution containing Au(III)/tectomer complex at pH 6.0 and 7.0; (c) Plot representing Au(III) concentration in the supernatant resulting from the addition of KBr in pH 2.0 buffer to Au(III)/tectomer layers on PLA supports. Table S2: Au(III) concentration in the supernatant resulting from the addition of KBr in pH 2.0 buffer to the Au(III)/tectomer layers on PLA supports. Table S3: Percentage of Au(III) released from the tectomer into the solution at pH 2.0.). Section S2: Optimization of experimental parameters for tyramine detection using Au(III)/tectomer sensor layers. (Figure S2: R coordinate as a function of the tyramine concentration for Au(III)/tectomer layers prepared using different pH buffers. Figure S3: R coordinate as a function of tyramine concentration for different Au(III)/tectomer molar ratios. Figure S4: Au(III)/tectomer sensing layer response to several tyramine concentrations at different pH values. Figure S5: R coordinate as a function of the pH of the buffers used to dissolve tyramine. [Tyramine] = 10 µM in all cases.). Section S3: Extraction method for the cheese samples.

Table S1: Atomic percentage of EVs isolated from cell cultures. Mean ± SD; Table S2: Nitrogen chemical environmental analysis of EVs isolated from cell cultures. Mean ± SD; Table S3: Percentage atomic composition of EVs isolated from female control donors (n = 6) and ovarian tumor patients of different tumor grades: I (n = 8), II (n = 1), III (n = 2) and IV (n = 7). Mean ± SD; Table S4: Nitrogen composition of EVs isolated from female control donors (n = 6) and ovarian tumor patients of different tumor grades: I (n = 8), II (n = 1), III (n = 2) and IV (n = 7). Mean ± SD; Table S5: Atomic composition of EVs isolated from healthy donors (n = 10) and pancreatic tumor patients (n = 10) at diagnosis. Mean ± SD; Table S6: Nitrogen composition of EVs isolated from healthy donors (n = 10) and pancreatic tumor patients (n = 10) at diagnosis. Mean ± SD.

Multiple development is a promising path to improved separations by thin-layer chromatography (TLC). It offers enhanced resolution for samples of wide polarity, but requires complex and time consuming handling steps. After some early attempts, automated multiple development (AMD) became a commercial reality around 1990. As the name implies, it represents the convergence of multiple development and automation to mostly remove problems derived from its complexity. Over about 20 years, AMD has become a settled and useful development technique, which has steadily evolved with the practice of TLC. We present here a general description of its origins, capabilities, current applications, and possible future trends. Applications are classified into nine different groups: lipids, pesticides/environmental analysis/hazardous compounds, lubricants/additives/petroleum products, pharmaceuticals/clinical applications, organics, plant extracts/bioactive metabolites, food and food additives, carbohydrates, and explosives.

Combined data on the migration of the studied standards (m.d. or RF) and UV spectra on silica gel. Migration of standards under different conditions and their recorded on-silica gel UV spectra. UV spectra of the separate peaks were consistent with those of the model compounds studied.-- Fig. 1S Migration distance (m.d. in mm, RF = migration distance of analyte / migration distance of the elution front) of studied standards in classic SARA. Fig. 2S Migration distance (m.d. in mm, RF = migration distance of analyte / migration distance of the elution front) of studied standards in 23-step THF‒DCM‒C7 AMD gradient. Fig. 3S On silica UV spectra of some studied standards: A) 1-octadecene, B) Tetralin, C) 9,10-Dihydrophenanthrene, D) Ethyl-naphthalene, E) Pyrene, F) Benzo (ghi) perylene.

Heterostructures of two-dimensional (2D) materials using graphene and MoS2 have enabled both pivotal fundamental studies and unprecedented sensing properties. These heterosystems are intriguing when graphene and MoS2 are interfaced with 2D sheets that emulate biomolecules, such as amino-terminated oligoglycine self-assemblies (known as tectomers). The adsorption of tectomer sheets over graphene and MoS2 modulates the physicochemical properties through electronic charge migration and mechanical stress transfer. Here, we present a systematic study by Raman spectroscopy and tectomer-functionalised scanning probe microscopy to understand mechanical strain, charge transfer and binding affinity in tectomer/graphene and tectomer/MoS2 hybrid structures. Raman mapping reveals distinctive thickness dependence of tectomer-induced charge transfer to MoS2, showing p-doping on monolayer MoS2 and n-doping on multilayer MoS2. By contrast, graphene is n-doped by tectomer independently of layer number, as confirmed by x-ray photoelectron spectroscopy. The interfacial adhesion between the amino groups and 2D materials are further explored using tectomer-functionalised probe microscopy. It is demonstrated here that these probes have potential for chemically sensitive imaging of 2D materials, which will be useful for mapping chemically distinct domains of surfaces and the number of layers. The facile tectomer-coating approach described here is an attractive soft-chemistry strategy for high-density amine-functionalisation of atomic force microscopy probes, therefore opening promising avenues for sensor applications.

The last triennium has shown a significant contribution of high-performance thin-layer chromatography (HPTLC) to lipidomics. HPTLC separation in combination with radio- and/or ultraviolet‒fluorescence (UV‒FL) densitometry was the technique of choice for tracking the transport of phospholipids among different cellular compartments in a number of biological systems, e.g., Gram-negative bacteria, yeast membranes, endoplasmic reticulum/mitochondrial membrane interface, and also to monitor the lipid transfer activity of a protein. Likewise, a significant number of HPTLC methods were developed to determine variations in the content of different lipid classes and subclasses after using genetic knockouts of cells. Radiolabeled control cells and cells whose genes were deleted using genomic editing allowed to study by HPTLC the effect of the disruption of the related proteins on the corresponding biosynthetic pathways. As well, direct interface-based coupling of HPTLC to mass spectrometry (MS) using mostly electrospray ionization(ESI) and a variety of mass analyzers, has gained new momentum in this period. Obtaining a large amount of information online in a very short time from complex biological samples, and the structural identification of target and non-target, unknown lipids, make this technique a useful tool for lipidomics. Quantitative issues related to HPTLC‒MS are also discussed in this work.

The question of whether exosome lipids can be considered as potential cancer biomarkers faces our current limited knowledge of their composition. This is due to the difficulty in isolating pure exosomes, the variability of the biological sources from which they are extracted, and the uncertainty of the methods for lipid characterization. Here, we present a procedure to isolate exosomes and obtain a deep, repeatable, and rapid phospholipid (PL) composition of their lipid extracts, from embryonic murine fibroblasts (NIH-3T3 cell line) and none (B16-F1) and high (B16-F10) metastatic murine skin melanoma cells. The analytical method is based on High Performance Thin-Layer Chromatography with Ultraviolet and fluorescence densitometry and coupled to Electrospray (ESI)-tandem Mass Spectrometry (MS). Under the conditions described in this work, separation and determination of PL classes, (sphingomyelins, SM; phosphatidylcholines, PC; phosphatidylserines, PS; and phosphatidylethanolamines, PE) were achieved, expressed as µg PL/100 µg exosome protein, obtained by bicinchoninic acid assay (BCA). A detailed structural characterization of molecular species of each PL class was performed by simultaneous positive and negative ESI-MS and MS/MS directly from the chromatographic plate, thanks to an elution-based interface.

An enzymatic method for the direct (without pretreatment) minimally invasive tyramine determination in cheese is proposed. Colorimetric test strips containing tyramine oxidase (TAO), peroxidase and 3,3′,5,5′-tetramethylbenzidine (Q-TAO), allow tyramine determination through the RGB chromatic coordinates of the observed blue colour (LOD = 2.6·10−6 M, LOQ = 8.7·10−6 M, RSD% (n = 5; 1.8·10−4 M) = 3.2%). The strips are inserted in the sample for 2 min and then the RGB coordinates are measured using a smartphone. Previously, these Q-TAO strips have been also optimized for tyramine determination in cheese extract. To do that, a spectrophotometric method in solution for tyramine determination in cheese extracts has been developed, which included an in-depth study of the indicating reaction; this study has allowed to gain new information about the spectroscopic properties of different TMB species and, which it is more important, to detect cross-reactions between TAO and TMB species. A mathematical model has also been developed which relate the RGB signals obtained with the tyramine concentrations, the instrumental characteristics of the smartphone and the spectroscopic properties of the absorbing product of the enzymatic reaction.

Amino-terminated oligoglycines non-covalently self-assemble, through cooperative hydrogen bonding formation, into biocompatible rigid 2D nanostructures called tectomers, either in solution or in surfacepromoted processes. Tectomers effectively coat carboxylated multi-walled carbon nanotubes (MWCNT-COOH) and strongly interact with graphene oxide (GO). Electrostatic interactions and hydrogen bonding formation accounts for the strong interfacial interaction of tectomers with MWCNTCOOH and GO, respectively. The resulting composites were characterized by electron- and atomic force microscopies, UV-vis and X-ray photoelectron (XPS) spectroscopies and contact angle measurements. Because of this high affinity of tectomers to GO, tectomers efficiently coat wet-spun GO fibers (Fig. 1). We also show that, due to their versatile surface chemistry, tectomers act as supramolecular peptidic adhesives for the immobilization of a variety of carbon nanomaterials, nanoparticles, molecules and drugs on the GO fiber surface therefore allowing GO fiber functionalization. The resulting ultrathin coatings exhibit remarkable water-resistant properties. This tectomer-based “double-sided sticky tape” fiber functionalization strategy can be extended to other fibers, fabrics and substrates, making it very attractive for technological and smart textile applications

Identification of 19 molecular species of globotriaosylceramides (Gb3) in extracts from a Fabry's plasma patient and a healthy control was performed by High-Performance Thin-Layer Chromatography (HPTLC)-densitometry and online coupling to Mass Spectrometry (MS). Separation was carried out on LiChrospher plates using Automated Multiple Development (AMD). Densitometry was performed on twin plates by combining detection in the visible at 550 nm, through previous on-plate orcinol derivatization, and by Ultraviolet 190 nm, using a non-impregnated plate. The latter was directly coupled to an ion-trap mass spectrometer through an automated elution-based interface. Gb3 molecular species, which were identified by HPTLC- Electrospray Mass Spectrometry (+)-MS and confirmed by MS/MS or HPTLC-Atmospheric Pressure Chemical Ionization Mass Spectrometry (+)-MS, are: five isoforms of saturated Gb3; seven isoforms of methylated Gb3; and seven species with two additional double bonds. Twelve of these species were previously reported as biomarkers of Fabry's lysosomal disorder using a Liquid Chromatography-MS-based method, and the other seven are structurally similar, closely related to them. Saturated Gb3 isoforms migrated on LiChrospher plate in one of the separated peaks corresponding to the migration zone of ceramide trihexosides standard. Instead, methylated and unsaturated Gb3 species co-migrated with sphingomyelin species. Ion intensity ESI-MS profiles show that saturated Gb3 species in Fabry's plasma were in higher concentration than in control sample. Before applying the Thin-Layer Chromatography (TLC)-MS interface on HPTLC separated peaks, its positioning precision was first studied using ceramide tri-hexosides as model compound. This provided information on Gb3 peak broadening and splitting during its migration.

This work is a review on HPTLC contribution to lipid analysis in complex matrices, in the period from 2010 to now, lapse of time where hyphenation with other techniques, especially Mass Spectrometry, has experienced an important growth. Scanning densitometry (SD)-UV/FL of separated lipids, as the core of detection and centerpiece for hyphenation, and its coupling with MS using soft ionization techniques (ESI, APCI, MALDI, DESI and others), are the central axis of this work. The occasional intercalation in this coupling of an on-plate biological assay for effect-direct analysis (EDA) of lipids, as well as the combination of SD with radio-densitometry (RD) using isotopically labeled-lipids are also covered topics. The described techniques make possible to develop strategies for obtaining qualitative and different levels of quantitative information, including untargeted lipids species. HPTLC of lipids has been used for: comparative purposes; fingerprinting; semi-quantitative determination, identification of species; or quantitative determination of a given individual lipid. Goals in molecular biology and biochemistry-related samples have been: preparative isolations; control of purity; verification of metabolic products; on-plate biological assays; profiles in cells; analysis of products from the cellular metabolism; measurement of enzymatic activities; monitoring lipid transport across membranes or at biological interfaces; or monitoring lipid dynamics.

Amino-terminated oligoglycines non-covalently self-assemble, through cooperative hydrogen bonding formation, into biocompatible rigid 2D nanostructures called tectomers. Tectomers effectively coat carboxylated multi-walled carbon nanotubes (MWCNT-COOH) and strongly interact with graphene oxide (GO). Electrostatic interactions and hydrogen bonding formation accounts for the strong interfacial interaction of tectomers with MWCNT-COOH and GO, respectively. Because of the high affinity of tectomers to GO, tectomers have been used to coat wet-spun GO fibers. We here show that, due to their versatile surface chemistry, tectomers act as supramolecular adhesives for nanomaterial and molecule immobilization on the GO fiber surface. Tectomer-coated GO fibers can then be subsequently decorated with a variety of carbon nanomaterials (carbon nanotubes, carbon nanohorns, carbon nanocones, and highly fluorescent nanodiamonds), metal (gold, platinum, iron) nanoparticles, acrylate-based polymer nanoparticles, fluorophores and drugs. The resulting ultrathin coatings exhibit remarkable water resistant properties. We show that this tectomer-based “double-sided sticky tape” fiber functionalization strategy can be extended to other fibers and fabrics, such as polyurethane/PEDOT:PSS, poly(methyl methacrylate) and polyester, making it very attractive for a variety of technological and smart textile applications.

Biogenic amines (BAs) are low molecular weight nitrogenous compounds that mainly result from the decarboxylation of free amino acids in food by microorganisms. At high concentrations, they cannot be metabolized by the body and pass to the blood stream, triggering intoxication processes.Because of the growing concern in food security, the quality control in food requires the development of fast and economic methods for the detection of BAs. Most methods are based on HPLC-MS techniques, and usually require a previous derivatization, so that they are expensive and tedious.The purpose of this work is the development of an optical sensor for the detection of BAs, as shown in Figure 1, where the enzymes amine oxidase (AO) and peroxidase (HRP), and a dye (ABTS) are immobilized on mica supports, so that the dye turns blue in presence of BAs.

A fully automated method for the effective drug screening of large populations based on dried blood spot (DBS) technology is presented. DBSs were prepared, scanned, then spiked with deuterated standards, and directly extracted, before they were transferred online to an analytical liquid chromatography (LC) column and then to the electrospray ionization tandem mass spectrometry (ESI-MS/MS) system. The method was applied to DBS samples from two patients with back pain; codeine and oxycodone could be identified and quantified accurately below the level of misuse of 89.6 ng/mL and 39.6 ng/mL, respectively.

Fully automated forensic screening of dried bloodspots was achieved by coupling a DBS-MS 500 system (CAMAG, Switzerland) to an LCMS system (Shimadzu, Japan). An increasing amount of prescription and illicit drugs drive clinical laboratories to more cost effective and faster screening methods in workplace drug testing, roadside testing, rehabilitation programs or post-mortem investigations without compromising established false positive or negative detection rates. Therefore, the increasing sample amount with a large panel of analytes needs to be handled in shorter analysis time and with simple sample preparation steps. In this study we present a fully automated dried bloodspot (DBS) extraction procedure coupled to an LC-MS/MS-system for forensic and toxicology screening of drugs and their metabolites. We use a new approach, the MRM Spectrum Mode, by measuring at least 5 MRM-transitions of each compound to generate a high confidence for the identification of the results.

Amino-terminated oligoglycine two-dimensional (2D) peptide self-assemblies (known as tectomers) have a versatile surface chemistry that allows them to interact with a variety of nanomaterials and to actas supramolecular adhesives for surface functionalization. Here, we have exploited the strong hydrogen-bond based interaction between tectomers and graphene oxide (GO) to functionalize GO fiber surfaces with different carbon nanomaterials (carbon nanotubes, carbon nanohorns, carbon nanocones, and highly fluorescent nanodiamonds), metal (gold, platinum, iron) nanoparticles, acrylate-based polymernanoparticles, fluorophores and drugs. The resulting ultrathin coatings exhibit remarkable water resis-tant properties. This tectomer-mediated fiber decoration strategy allows coating functionalities to be tailored by choosing the appropriate nanomaterials or other molecules. We show that this strategy can be extended to other fibers and fabrics, such as polyurethane/PEDOT:PSS, poly(methyl methacrylate) and polyester, making it very attractive for a variety of technological and smart textile applications.

High-performance thin-layer chromatography (HPTLC)-densitometry was directly combined with electrospray (ESI) tandem mass spectrometry for obtaining rapid and relevant structural identification of phospholipids (PL) species associated to membrane proteins (MP), in non-sulfur, purple bacteria having photosynthetic activity. Thus, species belonging to phosphatidylcholines (PC), phosphatidylethanolamines (PE), cardiolipins (CL) and phosphatidylglycerols (PG) associated to MP were investigated in bacterial membrane extracts from Rhodobacter (Rb.) blasticus, Rhodospirillum (R.) rubrum and Rhodobaca (Rbc.) bogoriensis, as well as those which are bound to a purified MP-photosynthetic complex from Rbc. bogoriensis. PL-classes were separated using a 7-step gradient-solvent sequence with a previous acid plate preconditioning, using Automated Multiple Development. Band zones of the plate corresponding to PL classes were selected to ensure their direct transfer to ion-trap MS equipment through an elution-based interface. Under the studied conditions, ESI+-MS spectra of PC and CL mostly showed sodium adducts ([M + Na]+) and [M-2H + 3Na]+, respectively, when recorded from the plate. The respective sodium adducts were fragmented in the ion-trap, and sodium remained as the charge of the fragment ions, thus being useful for their structural identification through MS/MS. ESI--MS and MS/MS spectra of CL were also obtained as [M-2H]2−, as well as those of PE and PG species as [M-H]- and [M]−, respectively. In this way, relative composition profiles of each studied PL-class by ESI-MS, and further identification of individual PL and the molecular species belonging to each of them by MS/MS were obtained.

A certified reagent kit for newborn screening was transferred on a fully automated dried blood spot platform. The dried blood spot cards are directly eluted and the extract is online guided to tandem mass spectrometry instrument, where the amino acid and acyl carnitine panel is detected. The method takes 2 minutes per sample and requires no human interaction for up to 500 samples. The method is fully standardized through the automation and the usage of only certified consumables and reference material. The manual reagent kit was first modified to fit the automated platform, secondly validated and third, successfully transferred into a routine newborn screening laboratory.

In this study, we describe the transfer of a new and fully automated workflow for the cost-effective drug screening of large populations based on the dried blood spot (DBS) technology. The method was installed at a routine poison control center and applied for DBS and dried urine spot (DUS) samples. A fast method focusing on the high-interest drugs and an extended screening method were developed on the automated platform. The dried cards were integrated into the automated workflow, in which the cards were checked in a camera recognition system, spiked with deuterated standards via an in-built spraying module and directly extracted. The extract was transferred online to an analytical LC column and then to the electrospray ionization tandem mass spectrometry system. The target compounds were analyzed in positive multiple-reaction monitoring mode. Before each sample batch or analysis day, calibration samples were measured to balance inter-day variations and to avoid false negative samples. An internal standard was integrated prior the sample extraction to allow in process control. A total of 28 target compounds were analyzed and directly extracted within 5 min per sample. This fast screening method was then extended to 20 min, enabling the usage of a Forensic Toxicology Database to screen over 1,200 drugs. The method gives confident positive/negative results for all tested drugs at their individual cut-off concentration. Good precision (±15%, respectively ±20% at limit of quantification) and correlation within the calibration range from 5 to 1,000 ng/mL was obtained. The method was finally applied to real cases from the lab and cross-checked with the existing methodologies.

HPTLC is well-adapted to providing lipid-class separations, as an assistant technique of HPLC. From this perspective, it can complement traditional LC-mass spectrometric approaches in a unique way. As the zones of interest on the plate can selectively be transferred to the ESI-MS instrument via an elution head-based interface, a rapid, relevant structural information about molecular species within each lipid classes from complex samples can be obtained. Separation using AMD2 provides lipid-classes as narrow peaks enough to ensure a direct elution and transfer of the plate zones to obtain both composition profiles of each class by ESI-MS, and identification of individual lipids and molecular species belonging to each separated lipid class by MS/MS (MSn) and HRMS. The respective sodium adducts of the above-mentioned lipid classes were fragmented in the positive ion mode using an ion-trap technology. The sodium remained the charge of their fragment ions, thus being useful for their structural identification by MS/MS (MSn) through further fragmentation. This work exemplarily focuses on profiling and identification of neutral lipids (NLs), sphingolipids (SLs) and phospholipids (PLs) in three analytical cases: (1) mono- (MAGs) and diacylglycerides (DAGs) in positive ion mode and fatty acids (FAs) in negative ion mode as impurities in a fatty acid methyl ester-based biodiesel (2) molecular species of neutral sphingolipids (SL), such as sphingomyelins (SMs) and globotriaosylceramides (Gb3), in human plasma (3) phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), phosphatidylglycerols (PGs) and cardiolipines (CLs) associated to membrane proteins of photosynthetic purple bacteria.

Here we present a route for non-covalent functionalization of carboxylated multi-walled carbon nanotubes and graphene oxide with novel two-dimensional peptide assemblies. We show that self-assembled amino-terminated biantennary and tetraantennary oligoglycine peptides (referred to as tectomers) effectively coat carboxylated multi-walled carbon nanotubes and also strongly interact with graphene oxide due to electrostatic interactions and hydrogen bonding as the driving force, respectively. The resulting hybrids can be made into free-standing conducting composites or applied in the form of thin, pH-switchable bioadhesive coatings onto graphene oxide fibers. Monitoring of cell viability of pancreatic cell lines, seeded on those CNT hybrids, show that they can be used as two- and three-dimensional scaffolds to tissue engineer tumour models for studying ex vivo the tumour development and response to treatment. This highly versatile method in producing pH-responsive hybrids and coatings offers an attractive platform for a variety of biomedical applications and for the development of functional materials such as smart textiles, sensors and bioelectronic devices.

Upon near-infrared excitation Tm+Yb doped fluorohafnate glasses present upconversion properties and emit visible light. This property permits to use these glasses (UCG) as excitation sources for fluorescent optical biosensors. Taking this into account, in this work a fluorescent biosensor for glucose determination is designed and evaluated. The biosensor combines the UCG and the fluorescence of the enzyme glucose oxidase chemically modified with a fluorescein derivative (GOx-FS), whose intensity is modified during the enzymatic reaction with glucose. Optical parameters have been optimized and a mathematical model describing the behavior of the analytical signal is suggested. Working in FIA mode, the biosensor responds to glucose concentrations up to, at least, 15 mM with a limit of detection of 1.9 mM. The biosensor has a minimum lifetime of 9 days and has been applied to glucose determination in drinks. The applicability of the sensor was tested by glucose determination in two fruit juices.

Berberrubine has been synthesized by microwave assisted selective demethylation of berberine. The high selectivity observed in this reaction has been explained and justified by means of computational calculations using Density Functional Theory (DFT) and Natural Resonance Theory (NRT). The existence of two resonant structures of berberrubine is the driving force of regioselective demethylation. Berberrubine is a chemosensor of alkanes, and may have practical applications in petrochemical analysis as a ‘mass’ detector because fluorescent response of saturated hydrocarbons does not depend on hydrocarbon chain length. Berberrubine operates via dipole-induced dipole interactions. Likewise, it has two fluorescent forms in acidic and basic media, which correspond to a keto-enol tautomerism. The fluorescent signal for berberrubine and the amplification of berberrubine-alkane signals by heating can be rationalized from the predominance of enol form when berberrubine is adsorbed onto silica gel.

Since most of the theoretical models of the effect of non-covalent interactions on fluorescence only consider wavelength shifts and no changes in quantum yields, no systematic analytical use of these interactions for quantitative measurements has been reported, with the exception of the quenching effect [1]. We have previously demonstrated that practically almost all molecules (potential analytes) produce a response in the emission of fluorophores (either increase or quenching) when interacting with them in a non-covalent way (either non-specific or specific interactions, respectively) at room temperature [2,3]. Sensitivity of this response is particularly high in silica gel medium [3]. Depending on the nature of fluorophore and analyte, changes in emission can additionally be associated to changes in emission wavelength. All this makes it possible to develop fingerprints or profiles of analytes based on their response against a collection of different types of fluorophores [4]. Development of an array of fluorophores for screening their interaction with analytes in a high-throughput format, using a silica gel-based combinatorial platform is presented here. This system may take advantage of the combined response of its components to create specific pattern responses or fingerprints for analyte discrimination. Arrays were prepared using 49 commercial or freshly-synthesized fluorophores with different chemical properties. They were immobilized by spray-on spotting on HPTLC silica gel plates through non-covalent adsorption. Fluorescence measurements of sprayed bands were then performed at five different wavelengths using scanning densitometry. Subsequent spray spotting of the corresponding target analyte on fluorophore bands was performed, and further fluorescence measurements recorded. Cholesterol and sphingomielin, which are not fluorescent molecules and have poor spectroscopical properties, were used as analytes. Parameters affecting repeatability of the procedure w

Low-toxic coralyne, a cationic benzo[c]phenanthridine type alkaloid (Fig. 1), has received extensive attention because of its DNA- and RNA-targeting properties, and antimicrobial, anticancer activity, more pronounced compared to other protoberberine alkaloids [1-3]. In a previous work we showed that the fluorescence intensity alteration of coralyne-impregnated silica gel plates allows the sensitive quantitative detection of a wide number of analytes by high-performance thin layer chromatographic techniques [4]. It has been shown that coralyne cation undergoes self-aggregation in aqueous solutions by stacking interactions, even at low dye concentration, being the dimer less fluorescent than the monomer [5, 6]. In this work we have studied the influence of temperature in dimer formation. Due to its large flat aromatic structure, coralyne also has a high tendency to penetration into organized assemblies in solution with hydrophobic core such as micelles or liposomes, and we present here a fluorescence study of coralyne in different microheterogeneous media. Fluorescence emission increases when coralyne probe is situated in apolar microenvironments which prevent non-radiative desexcitation pahtways (Fig. 2).

A complete molecular separation of heavy petroleum products is not feasible for their quality control. They are instead characterized in terms of chemical family composition, using classical Hydrocarbon Group Type Analysis such as SARA (Saturates, Aromatics, Resins, Asphaltenes). However, SARA does not provide information enough to correlate chemical differences of products with their conversion parameters in the case of heavy products. AMD appears as an interesting alternative to obtain different separations with increasing level of complexity for these products.

Berberine is a yellow alkaloid naturally produced by a diversity of plants. It is extracted from the roots, rhizome, and stem bark of several plants. This natural product has been used for centuries in the Chinese medicinal herb. Berberine presents a wide range of pharmacological applications such as antidiabetic, hypolipidemic, antihypertensive, anti-inflammatory, antioxidant, antidepressant, anticancer, antidiarrheal, hepatoprotective, and, above all, antimicrobial. It has been tested clinically in the treatment of oriental sore, diarrhea, trachoma, diabetes mellitus type 2, hypercholesterolemia, and congestive cardiac failure. This alkaloid is also used in the treatment of gastric and inflammatory diseases and more recently is being investigated for its application in neurology, cardiology, and oncology.

Many chemical compounds, including non-fluorescent ones, induce changes (either increase in emission or quenching) in the fluorescence spectra of coralyne cation, in absence and presence of solvent. We have applied this phenomenon to HPTLC with fluorescence scanning densitometry, using coralyne as a revealing agent, as a general detection system for analytes. It does not involve covalent interactions. Alkanes in presence of coralyne provide an enhancement of the fluorescent signal, which depends on alkane concentration and structure, when the system is irradiated with UV light. Responses of compounds other than alkanes are structure-dependent.