Smartphone-Based Sensing of Cortisol by Functionalized Rhodamine Probes.

During a stress condition, the human body synthesizes catecholamine neurotransmitters and specific hormones (called "stress hormones"), the most important of which is cortisol. The monitoring of cortisol levels should be extremely important to control the stress levels, and for this reason, it shows important medical applications. The common analytical methods (HPLC, GC-MS) cannot be used in real life, due to the bulky size of the instruments and the necessity of specialized personnel. Molecular probes solve these problems due to their fast and easy use. The synthesis of new fluorescent rhodamine probes, able to interact by non-covalent interactions with cortisol, the recognition properties in solution as well as in solid state by Strip Test, using a smartphone as detector, are here reported. DFT calculations and FT-IR measurements suggest the formation of supramolecular complexes through hydrogen bonds as main non-covalent interaction. The present study represents one of the first sensor, based on synthetical chemical receptors, able to detect cortisol in a linear range from 1 mM to 1 pM, based on non-covalent molecular recognition and paves the way to the realization of practical point-of-care device for the monitoring of cortisol in real live.

Role of Density and Conformational Composition in the Surface-to-Bulk Molecular Dosing of Photosensitive Surfactant Monolayers.

Poorly water-soluble photosensitive monolayers might enable very precise control of the rate and number of desorbing molecules by controlling both the monolayer density and conformational composition. In this perspective, we systematically characterized the interfacial behavior of Langmuir monolayers consisting of a poorly water-soluble azobenzene-containing surfactant as a function of its trans/cis ratio. Precise control of the conformational ratio was achieved by controlling the UV irradiation time, allowing researchers to investigate compositions spanning from 100% trans to 90% cis. Our results demonstrate that in 100% trans monolayers, molecules do not desorb with compression until a threshold area is reached. Instead, the number of molecules desorbing in mixed trans-cis monolayers can be modulated by controlling both the composition and the compression rate. Additionally, the desorption rate at constant density is also strongly composition-dependent, and it accounts for two different regimes with two different characteristic times. We will show that trans molecules mostly desorb according to the slow regime while cis molecules conform to the fast one, but the two conformers mutually influence each other.

Cortisol sensing by optical sensors.

During a stress condition, the human body synthesizes catecholamine neurotransmitters and specific hormones (called "stress hormones"), the most important of which is cortisol. The monitoring of cortisol levels is extremely important for controlling the stress levels. For this reason, it has important medical applications. Common analytical methods (HPLC, GC-MS) cannot be used in real life due to the bulkiness of the instruments and the necessity of specialized operators. Molecular probes solve this problem. This review aims to provide a description of recent developments in this field, focusing on the analytical aspects and the possibility to obtain real practical devices from these molecular probes.

A New BODIPY-Based Receptor for the Fluorescent Sensing of Catecholamines.

The human body synthesizes catecholamine neurotransmitters, such as dopamine and noradrenaline. Monitoring the levels of these molecules is crucial for the prevention of important diseases, such as Alzheimer's, schizophrenia, Parkinson's, Huntington's, attention-deficit hyperactivity disorder, and paragangliomas. Here, we have synthesized, characterized, and functionalized the BODIPY core with picolylamine (BDPy-pico) in order to create a sensor capable of detecting these biomarkers. The sensing properties of the BDPy-pico probe in solution were studied using fluorescence titrations and supported by DFT studies. Catecholamine sensing was also performed in the solid state by a simple strip test, using an optical fiber as the detector of emissions. In addition, the selectivity and recovery of the sensor were assessed, suggesting the possibility of using this receptor to detect dopamine and norepinephrine in human saliva.

Smartphone-Based Dopamine Detection by Fluorescent Supramolecular Sensor.

Supramolecular recognition of dopamine by two quinoxaline cavitands was studied in solution by fluorescence titrations, ESI-MS and ROESY measurements. In addition, the tetraquinoxaline cavitand was dropped onto a siloxane-based polymeric solid support, obtaining a sensor able to detect dopamine in a linear range of concentrations 10 Mm-100 pM, with a detection limit of 1 pM, much lower than the normal concentration values in the common human fluids (plasma, urine and saliva), by using a simple smartphone as detector. This sensor shows also good selectivity for dopamine respect to the other common analytes contained in a saliva sample and can be reused after acid-base cycles, paving the way for the realization of real practical sensor for human dopamine detection.

Agile Detection of Chemical Warfare Agents by Machine Vision: a Supramolecular Approach.

The supramolecular detection by image analysis of a simulant chemical warfare agent on a solid device containing a selective molecular sensor based on a BODIPY scaffold is reported. The recognition properties were investigated in solution, demonstrating high affinity (log K 6.60) and sensitivity (LOD 10 ppt). A test strip also confirmed the sensing properties in gas phase. Image analysis of the solid device allows quantitative information about the simulant to be obtained, recovering the sensor almost 5 times and thus confirming the goal of the supramolecular approach.

Supramolecular Sensing of a Chemical Warfare Agents Simulant by Functionalized Carbon Nanoparticles.

Real-time sensing of chemical warfare agents by optical sensors is today a crucial target to prevent terroristic attacks by chemical weapons. Here the synthesis, characterization and detection properties of a new sensor, based on covalently functionalized carbon nanoparticles, are reported. This nanosensor exploits noncovalent interactions, in particular hydrogen bonds, to detect DMMP, a simulant of nerve agents. The nanostructure of the sensor combined with the supramolecular sensing approach leads to high binding constant affinity, high selectivity and the possibility to reuse the sensor.

Supramolecular Detection of a Nerve Agent Simulant by Fluorescent Zn-Salen Oligomer Receptors.

We report on new Zn-Salen oligomer receptors able to recognize a nerve agent simulant, namely dimethyl methylphosphonate (DMMP), by a supramolecular approach. In particular, three Zn-Salen oligomers (Zn-Oligo-A, -B, and -C), differing by the length distribution, were obtained and characterized by NMR, Gel Permeation Chromatography (GPC), UV-Vis, and fluorescence spectroscopy. Furthermore, we investigated their recognition properties towards DMMP by using fluorescence measurements. We found that the recognition ability depends on the length of the oligomeric chain, and the Zn-Oligo-C shows a binding constant value higher than those already reported in literature for the DMMP detection.

Driving Coordination Polymer Monolayer Formation by Competitive Reactions at the Air/Water Interface.

We have developed a novel approach enabling us to follow and facilitate the formation of two-dimensional coordination polymer monolayers directly at the air/water interface without the need of complex instrumentation. The method is based on the use of a surface active ligand that, when spread at the air/water interface, progressively undergoes hydrolysis with consequent gradual decrease in surface pressure. Notably, if the aqueous subphase contains metal ions capable of coordinating the ligand, coordination competes with hydrolysis, resulting in a lower surface pressure decrease. As a consequence, the formation of the coordination polymer monolayer can be verified simply by surface pressure measurements. Competition between hydrolysis and coordination was investigated as a function of the main experimental parameters affecting the two reactions, enabling the formation of stable coordination polymer monolayers with controlled density. Finally, the formation of continuous rigid 2D layers was confirmed by compression isotherms and ex situ morphological characterization. This work will simplify the verification of coordination polymer monolayer formation; thus, it will boost the synthesis of novel and innovative 2D materials.

Supramolecular complexes for nanomedicine.

Host-guest interactions studied in supramolecular chemistry have been inspired by interactions between enzymes and substrates. Furthermore, most of the interactions involved in the cells are based on non-covalent bonds between two or more molecules. The common aspects between supramolecular chemistry and medicine have led to the development of a "new" area called "supramolecular medicine", in which non-covalent interactions and self-assembly processes are applied within several medical fields. The object of this Digest is to offer an account of how some macrocyclic hosts (e.g. cucurbiturils, cyclodextrins, pillararenes and calixarenes) are employed in supramolecular medicine creating new supramolecular hydrogels used as biomaterials for human tissue in regenerative medicine, and a diagnostic instrument, in-vitro and in-vivo, for the detection of diseases, as well as for the investigation of cell morphology.

A New Ratiometric Lysosomal Copper(II) Fluorescent Probe To Map a Dynamic Metallome in Live Cells.

We synthesized a new ratiometric fluorescent Cu2+ probe, bearing a morpholine moiety for selective binding to lysosomes and two picolylamine arms for the specific chelation of divalent copper ions. The probe capability to detect lysosomal Cu2+ was demonstrated in human differentiated neuroblastoma cells by confocal microscopy.

Nerve Gas Simulant Sensing by a Uranyl-Salen Monolayer Covalently Anchored on Quartz Substrates.

A uranyl complex monolayer that easily allows the optical detection of a nerve gas simulant, namely, dimethyl methylphosphonate, is reported. Both UV/Vis spectroscopy and photoelectron data confirm that the functional hybrid material coordinates a Lewis base by means of the P=O group, which interacts with the uranium equatorial site available for complexation.

Fluorescent Copper Probe Inhibiting Aß1-16-Copper(II)-Catalyzed Intracellular Reactive Oxygen Species Production.

A variety of fluorescent probes are proposed to monitor the intracellular copper content. So far, none of the probes have been evaluated for their potential to inhibit copper-associated intracellular oxidative stress. Herein, we studied the ability of a fluorescent copper probe, OBEP-CS1, to inhibit intracellular oxidative stress associated with an amyloid ß (Aß) peptide-copper complex. The data showed that OBEP-CS1 completely inhibits the copper-catalyzed oxidation as well as decarboxylation/deamination of Aß1-16. Moreover, the cell imaging experiments confirmed that OBEP-CS1 can inhibit Aß-CuII-catalyzed reactive oxygen species production in SH-SY5Y cells. We also demonstrated that Aß1-16 peptide can bind intracellular copper and thereby exert oxidative stress.

(Salen)Mn(III) Catalyzed Asymmetric Epoxidation Reactions by Hydrogen Peroxide in Water: A Green Protocol.

Enantioselective epoxidation reactions of some chosen reactive alkenes by a chiral Mn(III) salen catalyst were performed in H2O employing H2O2 as oxidant and diethyltetradecylamine N-oxide (AOE-14) as surfactant. This procedure represents an environmentally benign protocol which leads to e.e. values ranging from good to excellent (up to 95%).

Smart Sensing of Nerve Agents.

The recent international scenario highlights the importance to protect human health and environmental quality from toxic compounds. In this context, organophosphorous (OP) Nerve Agents (NAs) have received particular attention, due to their use in terrorist attacks. Classical instrumental detection techniques are sensitive and selective, but they cannot be used in real field due to the high cost, specialized personnel requested and huge size. For these reasons, the development of practical, easy and fast detection methods (smart methods) is the future of this field. Indeed, starting from initial sensing research, based on optical and/or electrical sensors, today the development and use of smart strategies to detect NAs is the current state of the art. This review summarizes the smart strategies to detect NAs, highlighting some important parameters, such as linearity, limit of detection and selectivity. Furthermore, some critical comments of the future on this field, and in particular, the problems to be solved before a real application of these methods, are provided.

Dopamine sensing by fluorescent carbon nanoparticles synthesized using artichoke extract.

The practical and easy detection of dopamine levels in human fluids, such as urine and saliva, is of great interest due to the correlation of dopamine concentration with several diseases. In this work, the one-step synthesis of water-soluble carbon nanoparticles (CNPs), starting from artichoke extract, containing catechol groups, for the fluorescence sensing of dopamine is reported. Size, morphology, chemical composition and electronic structure of CNPs were elucidated by DLS, AFM, XPS, FT-IR, EDX and TEM analyses. Their optical properties were then explored by UV-vis and fluorescence measurements in water. The dopamine recognition properties of these CNPs were investigated in water through fluorescence measurements and we observed the progressive enhancement of the CNP emission intensity upon the progressive addition of dopamine, with a binding affinity value of log K = 5.76 and a detection limit of 0.81 nM. Selectivity towards dopamine was tested over other interfering analytes commonly present in human saliva. Finally, in order to perform a solid point of care test, CNPs were adsorbed on a solid support and exposed to different concentrations of dopamine, thus observing a pseudo-linear response, using a smartphone as a detector. Therefore, the detection of dopamine in simulated human saliva was performed with excellent results, in terms of selectivity and a detection limit of 100 pM.

Supramolecular Detection of a Sub-ppm Nerve Agent Simulant by a Smartphone Tool.

The widespread use of smartphones and related tools is extending their applications in several fields. Herein, we report a reusable smartphone coupled portable detection system for the sensing of sub-ppm level of a nerve agent mimic (dimethylmethylphosphonate) in the gas phase. The detection system is based on multiple hydrogen-bond interactions of the vapor analyte with an ad-hoc functionalized Bodipy chromophore scaffold. The multitopic approach used for the molecular recognition of DMMP leads to the highest binding constant values, high selectivity, and low limits of detection.

Pair of diastereomeric uranyl salen cavitands displaying opposite enantiodiscrimination of α-amino acid ammonium salts.

A pair of diastereomeric salen cavitands and their uranyl complexes combine a chiral (R,R) salen bridge and an inherent chiral tris-bridged quinoxaline cup within the same molecule. Whereas the free ligands show a preference for the same enantiomer of an α-amino acid pair, the corresponding UO(2) complexes display opposite enantiodiscrimination and exceptionally high enantioselectivities (K(D)/K(L) = 26.4).

Nanomaterials for Cortisol Sensing.

Space represents one of the most dangerous environments for humans, which can be affected by high stress levels. This can lead to severe physiological problems, such as headaches, gastrointestinal disorders, anxiety, hypertension, depression, and coronary heart diseases. During a stress condition, the human body produces specific hormones, such as dopamine, adrenaline, noradrenaline, and cortisol. In particular, the control of cortisol levels can be related to the stress level of an astronaut, particularly during a long-term space mission. The common analytical methods (HPLC, GC-MS) cannot be used in an extreme environment, such as a space station, due to the steric hindrance of the instruments and the absence of gravity. For these reasons, the development of smart sensing devices with a facile and fast analytical protocol can be extremely useful for space applications. This review summarizes the recent (from 2011) miniaturized sensoristic devices based on nanomaterials (gold and carbon nanoparticles, nanotubes, nanowires, nano-electrodes), which allow rapid and real-time analyses of cortisol levels in biological samples (such as saliva, urine, sweat, and plasma), to monitor the health conditions of humans under extreme stress conditions.

Fluorescence sensing by carbon nanoparticles.

Sensing is one of the most important fields in which chemists, engineers and other scientists are involved to realize sensoristic devices that can detect different analytes, both chemicals and biologicals. In this context, fluorescence sensing paves the way for the realization of smart sensoristic devices due to the possibility to detect the target analyte via a change in colour or emission. Recently (since 2006), carbon nanoparticles, which are a "new class" of nanostructures based on carbon atoms, have been widely used in sensing applications due to their intriguing optical properties. The scientific literature on this topic started from 2006 and a progressive increase in the corresponding number of publications has been observed. This review summarises the application of carbon nanoparticles in the sensing field, focusing on chemical and ion sensing.