Forensic Analysis of Synthetic Cathinones on Nanomaterials-Based Platforms: Chemometric-Assisted Voltametric and UPLC-MS/MS Investigation.

Synthetic cathinones (SCs) are a group of new psychoactive substances often referred to as "legal highs" or "bath salts", being characterized by a dynamic change, new compounds continuously emerging on the market. This creates a lack of fast screening tests, making SCs a constant concern for law enforcement agencies. Herein, we present a fast and simple method for the detection of four SCs (alpha-pyrrolidinovalerophenone, N-ethylhexedrone, 4-chloroethcathinone, and 3-chloromethcathinone) based on their electrochemical profiles in a decentralized manner. In this regard, the voltametric characterization of the SCs was performed by cyclic and square wave voltammetry. The elucidation of the SCs redox pathways was successfully achieved using liquid chromatography coupled to (tandem) mass spectrometry. For the rational identification of the ideal experimental conditions, chemometric data processing was employed, considering two critical qualitative and quantitative variables: the type of the electrochemical platform and the pH of the electrolyte. The analytical figures of merit were determined on standard working solutions using the optimized method, which exhibited wide linear ranges and LODs suitable for confiscated sample screening. Finally, the performance of the method was evaluated on real confiscated samples, the resulting validation parameters being similar to those obtained with another portable device (i.e., Raman spectrometer).

Toward microfluidic SERS and EC-SERS applications via tunable gold films over nanospheres.

Many promising applications of surface-enhanced Raman scattering (SERS), such as microfluidic SERS and electrochemical (EC)-SERS, require immersion of plasmonic nanostructured films in aqueous media. Correlational investigations of the optical response and SERS efficiency of solid SERS substrates immersed in water are absent in the literature. This work presents an approach for tuning the efficiency of gold films over nanospheres (AuFoN) as SERS substrates for applications in aqueous environment. AuFoN are fabricated by convective self-assembly of colloidal polystyrene nanospheres of various diameters (300-800 nm), followed by magnetron sputtering of gold films. The optical reflectance of the AuFoN and Finite-Difference Time-Domain simulations in both water and air reveal the dependence of the surface plasmon band on nanospheres' diameter and environment. SERS enhancement of a common Raman reporter on AuFoN immersed in water is analyzed under 785 nm laser excitation, but also using the 633 nm line for the films in air. The provided correlations between the SERS efficiency and optical response in both air and water indicate the best structural parameters for high SERS efficiency and highlight a route for predicting and optimizing the SERS response of AuFoN in water based on the behavior in air, which is more practical. Finally, the AuFoN are successfully tested as electrodes for EC-SERS detection of the thiabendazole pesticide and as SERS substrates integrated in a flow-through microchannel format. The obtained results represent an important step toward the development of microfluidic EC-SERS devices for sensing applications.

Gold vs. Silver Colloidal Nanoparticle Films for Optimized SERS Detection of Propranolol and Electrochemical-SERS Analyses.

The increasing pollution of surface and groundwater bodies by pharmaceuticals is a general environmental problem requiring routine monitoring. Conventional analytical techniques used to quantify traces of pharmaceuticals are relatively expensive and generally demand long analysis times, associated with difficulties in performing field analyses. Propranolol, a widely used ß-blocker, is representative of an emerging class of pharmaceutical pollutants with a noticeable presence in the aquatic environment. In this context, we focused on developing an innovative, highly accessible analytical platform based on self-assembled metal colloidal nanoparticle films for the fast and sensitive detection of propranolol based on Surface Enhanced Raman Spectroscopy (SERS). The ideal nature of the metal used as the active SERS substrate was investigated by comparing silver and gold self-assembled colloidal nanoparticle films, and the improved enhancement observed on the gold substrate was discussed and supported by Density Functional Theory calculations, optical spectra analyses, and Finite-Difference Time-Domain simulations. Next, direct detection of propranolol at low concentrations was demonstrated, reaching the ppb regime. Finally, we showed that the self-assembled gold nanoparticle films could be successfully used as working electrodes in electrochemical-SERS analyses, opening the possibility of implementing them in a wide array of analytical applications and fundamental studies. This study reports for the first time a direct comparison between gold and silver nanoparticle films and, thus, contributes to a more rational design of nanoparticle-based SERS substrates for sensing applications.

Topical Treatment for Retinal Degenerative Pathologies: A Systematic Review.

The topical administration of medicines is the preferred route in ocular therapy, at least for the anterior segment of the eye. However, the eye's inherent functional and biological barriers all work against the active pharmaceutical ingredient (API) to efficiently reach the targeted retinal structures. The main objective of this article is to offer a systematic review of the scientific literature in recent years, focusing on the latest developments of topical treatment intended for retinal degenerative diseases. Database search returned 102 clinical studies, focused on topical treatment for age macular degeneration, macular edemas (in diabetic retinopathy, surgery related or in retinal dystrophies) or glaucoma. After the exclusion of low-powered studies and those combining vitreo-retinal surgery, 35 articles remained for analysis. Currently, the topical treatment of retinal degenerative diseases is limited by the difficulty to deliver effective drug concentrations to the posterior eye structures. However, in the case of drug classes like NSAIDs, the presence of certain molecular and metabolic features for specific representatives makes the topical administration currently feasible in several clinical contexts. For other drug classes, either a fine-tuning of the API's pharmacokinetic profile or the use of more advanced formulation strategies, such as rationally designed nanostructured drugs and vehicles, crystalline polymorphs or supramolecular complexes, could bring the much awaited breakthrough for a more predictable and controlled delivery towards the retinal structures and could eventually be employed in the future for the development of more effective ways of delivering drugs to the posterior eye, with the ultimate goal of improving their clinical efficacy.

Ruxolitinib-Loaded Imprinted Polymeric Drug Reservoir for the Local Management of Post-Surgical Residual Glioblastoma Cells.

(1) Background: The current limitations of glioblastoma (GBM) chemotherapy were addressed by developing a molecularly imprinted polymer (MIP)-based drug reservoir designed for the localized and sustained release of ruxolitinib (RUX) within the tumor post-resection cavity, targeting residual infiltrative cancerous cells, with minimum toxic effects toward normal tissue. (2) Methods: MIP reservoirs were synthesized by precipitation polymerization using acrylamide, trifluoromethacrylic acid, methacrylic acid, and styrene as monomers. Drug release profiles were evaluated by real-time and accelerated release studies in phosphate-buffered solution as a release medium. The cytotoxicity of polymers and free monomers was evaluated in vitro on GBM C6 cells using the Alamar Blue assay, optical microscopy, and CCK8 cell viability assay. (3) Results: Among the four synthesized MIPs, trifluoromethacrylic acid-based polymer (MIP 2) was superior in terms of loading capacity (69.9 µg RUX/mg MIP), drug release, and efficacy on GBM cells. Accelerated drug release studies showed that, after 96 h, MIP 2 released 42% of the loaded drug at pH = 7.4, with its kinetics fitted to the Korsmeyer-Peppas model. The cell viability assay proved that all studied imprinted polymers provided high efficacy on GBM cells. (4) Conclusions: Four different drug-loaded MIPs were developed and characterized within this study, with the purpose of obtaining a drug delivery system (DDS) embedded in a fibrin-based hydrogel for the local, post-surgical administration of RUX in GBM in animal models. MIP 2 emerged as superior to the others, making it more suitable and promising for further in vivo testing.

EC-SERS detection of thiabendazole in apple juice using activated screen-printed electrodes.

Thiabendazole (TBZ), a benzimidazole fungicide used for post-harvest treatment, may be a trace contaminant of food matrices. In this work, we report the first EC-SERS (electrochemical-surface enhanced Raman spectroscopy) detection of TBZ in spiked apple juice using electrochemically (EC) roughened, gold-based screen-printed electrodes (AuSPEs) and portable instrumentation. Polarizing the substrate (-0.8 V vs Ag/AgCl) improves the recorded SERS signal of TBZ, allowing to reach a limit of detection (LOD) in juice of 0.061 ppm with a relatively wide linear range (0.5-10 µM) and good intermediate precision (%RSD < 10). The recovery of TBZ from unprocessed juice was found to be more than 82 %. Furthermore, a proof-of-concept integration of AuSPEs with a miniaturized flow cell for the preconcentration of TBZ and the controlled delivery of sample and reagents has been demonstrated. This approach paves the way for integrated, portable analytical systems applicable for on-site sample collection, processing, and analysis.

In Vivo Applications of Molecularly Imprinted Polymers for Drug Delivery: A Pharmaceutical Perspective.

Molecularly imprinted polymers (MIPs) have been proven to be a promising candidate for drug delivery systems (DDS) due to their ability to provide a sustained and controlled drug release, making them useful for treating a wide range of medical conditions. MIP-based DDS offer many advantages, including the administration of a smaller drug doses, due to the higher drug payload or targeted delivery, resulting in fewer side effects, as well as the possibility of attaining high concentrations of the drug in the targeted tissues. Whether designed as drug reservoirs or targeted DDS, MIPs are of great value to drug delivery as conventional drug formulations can be redesigned as DDS to overcome the active pharmaceutical ingredient's (APIs) poor bioavailability, toxic effects, or other shortcomings that previously made them less efficient or unsuitable for therapy. Therefore, MIP design could be a promising alternative to the challenging research and development of new lead compounds. Research on MIPs is primarily conducted from a material science perspective, which often overlooks some of their key pharmaceutical requirements. In this review, we emphasize the specific features that make MIPs suitable for clinical use, from both a material science and a biopharmaceutical perspective.

Review on combining surface-enhanced Raman spectroscopy and electrochemistry for analytical applications.

The discovery of surface enhanced Raman scattering (SERS) from an electrochemical (EC)-SERS experiment is known as a historic breakthrough. Five decades have passed and Raman spectroelectrochemistry (SEC) has developed into a common characterization tool that provides information about the electrode-electrolyte interface. Recently, this technique has been successfully explored for analytical purposes. EC was found to highly improve the performances of SERS sensors, providing, among others, controlled adsorption of analytes and increased reproducibility. In this review, we highlight the potential of EC-SERS sensors to be implemented for point-of-need (PON) analyses as miniaturized devices, and their ability to revolutionize fields like quality control, diagnosis or environmental and food safety. Important developments have been achieved in Raman spectroelectrochemistry, which now represents a promising alternative to conventional analytical methods and interests more and more researchers. The studies included in this review open endless possibilities for real-life EC-SERS analytical applications.

Analytical Perspectives in the Study of Polyvalent Interactions of Free and Surface-Bound Oligonucleotides and Their Implications in Affinity Biosensing.

The high affinity and/or selectivity of oligonucleotide-mediated binding offers a myriad of therapeutical and analytical applications, whose rational design implies an accurate knowledge of the involved molecular mechanisms, concurring equilibrium processes and key affinity parameters. Oligonucleotide-functionalized gold surfaces or nanostructures are regularly employed analytical platforms for the development of label-free optical or electrochemical biosensors, and recently, novel detection platform designs have been increasingly considering the synergistic effect of polyvalent binding, involving the simultaneous interaction of two or several oligonucleotide strands. Considering the general lack of studies involving ternary single-stranded DNA (ssDNA) interactions, a complementary analytical workflow involving capillary gel electrophoretic (CGE) mobility shift assay, microcalorimetry and computational modeling has been deployed for the characterization of a series of free and surface-bound binary and ternary oligonucleotide interactions. As a proof of concept, the DNA analogue of MicroRNA 21 (miR21), a well-known oncogenic short MicroRNA (miRNA) sequence, has been chosen as a target molecule, simulating limiting-case scenarios involved in dual molecular recognition models exploited in affinity (bio)sensing. Novel data for the characterization of oligonucleotide interacting modules is revealed, offering a fast and complete mapping of the specific or non-specific, often competing, binary and ternary order interactions in dynamic equilibria, occurring between various free and metal surface-bound oligonucleotides.

Simulation of the oxidative metabolization pattern of netupitant, an NK1 receptor antagonist, by electrochemistry coupled to mass spectrometry.

Considering the frequent use of netupitant in polytherapy, the elucidation of its oxidative metabolization pattern is of major importance. However, there is a lack of published research on the redox behavior of this novel neurokinin-1 receptor antagonist. Therefore, this study was performed to simulate the intensive hepatic biotransformation of netupitant using an electrochemically driven method. Most of the known enzyme-mediated reactions occurring in the liver (i.e., N-dealkylation, hydroxylation, and N-oxidation) were successfully mimicked by the electrolytic cell using a boron-doped diamond working electrode. The products were separated by reversed-phase high-performance liquid chromatography and identified by high-resolution mass spectrometry. Aside from its ability to pinpoint formerly unknown metabolites that could be responsible for the known side effects of netupitant or connected with any new perspective concerning future therapeutic indications, this electrochemical process also represents a facile alternative for the synthesis of oxidation products for further in vitro and in vivo studies.

Perspectives of Molecularly Imprinted Polymer-Based Drug Delivery Systems in Ocular Therapy.

Although the human eye is an easily accessible sensory organ, it remains a challenge for drug administration due to the presence of several anatomical and physiological barriers which limit the access of drugs to its internal structures. Molecular imprinting technology may be considered the avant-garde approach in advanced drug delivery applications and, in particular, in ocular therapy. In fact, molecularly imprinted polymers hold the promise to compensate for the current shortcomings of the available arsenal of drug delivery systems intended for ocular therapy. The present manuscript aims to review the recent advances, the current challenges and most importantly to raise awareness on the underexplored potential and future perspectives of molecularly imprinted polymer-based drug delivery systems intended for the treatment of eye diseases.

Strategies for SERS Detection of Organochlorine Pesticides.

Organochlorine pesticides (OCPs) embody highly lipophilic hazardous chemicals that are being phased out globally. Due to their persistent nature, they are still contaminating the environment, being classified as persistent organic pollutants (POPs). They bioaccumulate through bioconcentration and biomagnification, leading to elevated concentrations at higher trophic levels. Studies show that human long-term exposure to OCPs is correlated with a large panel of common chronic diseases. Due to toxicity concerns, most OCPs are listed as persistent organic pollutants (POPs). Conventionally, separation techniques such as gas chromatography are used to analyze OCPs (e.g., gas chromatography coupled with mass spectrometry (GC/MS)) or electron capture detection (GC/ECD). These are accurate, but expensive and time-consuming methods, which can only be performed in centralized lab environments after extensive pretreatment of the collected samples. Thus, researchers are continuously fueling the need to pursue new faster and less expensive alternatives for their detection and quantification that can be used in the field, possibly in miniaturized lab-on-a-chip systems. In this context, surface enhanced Raman spectroscopy (SERS) represents an exceptional analytical tool for the trace detection of pollutants, offering molecular fingerprint-type data and high sensitivity. For maximum signal amplification, two conditions are imposed: an efficient substrate and a high affinity toward the analyte. Unfortunately, due to the highly hydrophobic nature of these pollutants (OCPs,) they usually have a low affinity toward SERS substrates, increasing the challenge in their SERS detection. In order to overcome this limitation and take advantage of on-site Raman analysis of pollutants, researchers are devising ingenious strategies that are synthetically discussed in this review paper. Aiming to maximize the weak Raman signal of organochlorine pesticides, current practices of increasing the substrate's performance, along with efforts in improving the selectivity by SERS substrate functionalization meant to adsorb the OCPs in close proximity (via covalent, electrostatic or hydrophobic bonds), are both discussed. Moreover, the prospects of multiplex analysis are also approached. Finally, other perspectives for capturing such hydrophobic molecules (MIPs-molecularly imprinted polymers, immunoassays) and SERS coupled techniques (microfluidics-SERS, electrochemistry-SERS) to overcome some of the restraints are presented.

Off-Resonance Gold Nanobone Films at Liquid Interface for SERS Applications.

Extensive effort and research are currently channeled towards the implementation of SERS (Surface Enhanced Raman Spectroscopy) as a standard analytical tool as it has undisputedly demonstrated a great potential for trace detection of various analytes. Novel and improved substrates are continuously reported in this regard. It is generally believed that plasmonic nanostructures with plasmon resonances close to the excitation wavelength (on-resonance) generate stronger SERS enhancements, but this finding is still under debate. In the current paper, we compared off-resonance gold nanobones (GNBs) with on-resonance GNBs and gold nanorods (GNRs) in both colloidal dispersion and as close-packed films self-assembled at liquid-liquid interface. Rhodamine 6G (R6G) was used as a Raman reporter in order to evaluate SERS performances. A 17-, 18-, and 55-fold increase in the Raman signal was observed for nanostructures (off-resonance GNBs, on-resonance GNBs, and on-resonance GNRs, respectively) assembled at liquid-liquid interface compared to the same nanostructures in colloidal dispersion. SERS performances of off-resonance GNBs were superior to on-resonance nanostructures in both cases. Furthermore, when off-resonance GNBs were assembled at the liquid interface, a relative standard deviation of 4.56% of the recorded signal intensity and a limit of detection (LOD) of 5 × 10-9 M could be obtained for R6G, rendering this substrate suitable for analytical applications.

Simulation of the oxidative metabolization pattern of netupitant,an NK1 receptor antagonist,by electrochemistry coupled to mass spectrometry / 药物分析学报

Considering the frequent use of netupitant in polytherapy,the elucidation of its oxidative metabolization pattern is of major importance.However,there is a lack of published research on the redox behavior of this novel neurokinin-1 receptor antagonist.Therefore,this study was performed to simulate the intensive hepatic biotransformation of netupitant using an electrochemically driven method.Most of the known enzyme-mediated reactions occurring in the liver(i.e.,N-dealkylation,hydroxylation,and N-oxidation)were successfully mimicked by the electrolytic cell using a boron-doped diamond working electrode.The products were separated by reversed-phase high-performance liquid chromatography and identified by high-resolution mass spectrometry.Aside from its ability to pinpoint formerly unknown metabolites that could be responsible for the known side effects of netupitant or connected with any new perspective concerning future therapeutic indications,this electrochemical process also represents a facile alternative for the synthesis of oxidation products for further in vitro and in vivo studies.

Analytical techniques for multiplex analysis of protein biomarkers.

INTRODUCTION: The importance of biomarkers for pharmaceutical drug development and clinical diagnostics is more significant than ever in the current shift toward personalized medicine. Biomarkers have taken a central position either as companion markers to support drug development and patient selection, or as indicators aiming to detect the earliest perturbations indicative of disease, minimizing therapeutic intervention or even enabling disease reversal. Protein biomarkers are of particular interest given their central role in biochemical pathways. Hence, capabilities to analyze multiple protein biomarkers in one assay are highly interesting for biomedical research. AREAS COVERED: We here review multiple methods that are suitable for robust, high throughput, standardized, and affordable analysis of protein biomarkers in a multiplex format. We describe innovative developments in immunoassays, the vanguard of methods in clinical laboratories, and mass spectrometry, increasingly implemented for protein biomarker analysis. Moreover, emerging techniques are discussed with potentially improved protein capture, separation, and detection that will further boost multiplex analyses. EXPERT COMMENTARY: The development of clinically applied multiplex protein biomarker assays is essential as multi-protein signatures provide more comprehensive information about biological systems than single biomarkers, leading to improved insights in mechanisms of disease, diagnostics, and the effect of personalized medicine.

Biomimetic electrochemical sensor for the highly selective detection of azithromycin in biological samples.

A highly selective and sensitive molecularly imprinted polymer (MIP)-based electrochemical sensor was fabricated for the determination of azithromycin, a broad-spectrum macrolide antibiotic, from various biological samples (urine, tears, plasma). The reversible boronate ester bond-mediated, thin (~75 nm) MIP-based biomimetic recognition layer was electrodeposited in non-aqueous media onto the surface of a glassy carbon electrode (GCE). The surface morphology and the analytical performances of the developed sensor were assessed by scanning electron (SEM) and atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). By employing an indirect electrochemical detection in the presence of 10 mM ferro/ferricyanide as redox probe, the sensor exhibited a very wide dynamic range (13.33 nM-66.67 µM), with an estimated detection limit in the subnanomolar range (0.85 nM azithromycin). The simple to construct sensor demonstrates reusability and good shelf-life, exhibiting remarkable selectivity over a wide number of structurally related and non-related antibiotics, commonly associated drugs and endogenous compounds.

Perspectives of Molecularly Imprinted Polymer-Based Drug Delivery Systems in Cancer Therapy.

Despite the considerable effort made in the past decades, multiple aspects of cancer management remain a challenge for the scientific community. The severe toxicity and poor bioavailability of conventional chemotherapeutics, and the multidrug resistance have turned the attention of researchers towards the quest of drug carriers engineered to offer an efficient, localized, temporized, and doze-controlled delivery of antitumor agents of proven clinical value. Molecular imprinting of chemotherapeutics is very appealing in the design of drug delivery systems since the specific and selective binding sites created within the polymeric matrix turn these complex structures into value-added carriers with tunable features, notably high loading capacity, and a good control of payload release. Our work aims to summarize the present state-of-the art of molecularly imprinted polymer-based drug delivery systems developed for anticancer therapy, with emphasis on the particularities of the chemotherapeutics' release and with a critical assessment of the current challenges and future perspectives of these unique drug carriers.

Bioactive Aliphatic Polycarbonates Carrying Guanidinium Functions: An Innovative Approach for Myotonic Dystrophy Type 1 Therapy.

Dystrophia myotonica type 1 (DM1) results from nuclear sequestration of splicing factors by a messenger RNA (mRNA) harboring a large (CUG) n repeat array transcribed from the causal (CTG) n DNA amplification. Several compounds were previously shown to bind the (CUG) n RNA and release the splicing factors. We now investigated for the first time the interaction of an aliphatic polycarbonate carrying guanidinium functions to DM1 DNA/RNA model probes by affinity capillary electrophoresis. The apparent association constants (K a) were in the range described for reference compounds such as pentamidine. Further macromolecular engineering could improve association specificity. The polymer presented no toxicity in cell culture at concentrations of 1.6-100.0 µg/mL as evaluated both by MTT and real-time monitoring xCELLigence method. These promising results may lay the foundation for a new branch of potential therapeutic agents for DM1.

Selectivity evaluation of phenyl based stationary phases for the analysis of amino acid diastereomers by liquid chromatography coupled with mass spectrometry.

D-amino acids (AA) analysis is becoming more and more relevant for metabolomics, therefore new analytical tools need to be developed. A common approach to achieve AA enantioseparation is chiral derivatization. Among the chiral derivatization reagents, (+) or (-)-1-(9-fluorenyl) ethyl chloroformate ((+) or (-)-FLEC) has proved to be one of the most versatile. Suitable chiral selectivity for FLEC derivatives of amino acids could be obtained in reversed-phase HPLC using nonpolar stationary phases (C4, C8 and C18) and tetrahydrofuran (THF) based mobile phases. This study is meant to provide alternatives to the use of THF as organic modifier by evaluating the selectivity obtained on two phenyl based stationary phases for 19 FLEC-DL-AA pairs of diastereomers using UHPLC-MS. Several mobile phases consisting of ammonium acetate and different common organic solvents (acetonitrile (ACN), methanol (MeOH), 2-propanol (IPA)) were tested using gradient elution. Experimental design was employed for the optimization of the separation conditions. In the optimized conditions, complete chiral separation can be achieved for 18 out of 19 FLEC-DL-AAs in less than 30 min.

Correction to: Affinity capillary electrophoresis for identification of active drug candidates in myotonic dystrophy type 1.

Unfortunately the name of Jean Jacques Vanden Eynde was missing as co-author of this contribution. The correct list of authors is: Ioan O. Neaga, Stephanie Hambye, Ede Bodoki, Claudio Palmieri, Jean Jacques Vanden Eynde, Eugénie Ansseau, Alexandra Belayew, Radu Oprean, Bertrand Blankert.