Comparative SERS Activity of Homometallic and Bimetallic Core-Satellite Assemblies.

The fabrication of core-satellite (CS) assemblies offers a versatile strategy for tailoring the optical properties of plasmonic nanomaterials. In addition to key factors like size, shape, and spatial arrangement of individual components, the combination of plasmonic units with different compositions (e.g.

Screen-Printed Carbon Electrodes with Cationic Cyclodextrin Carbon Nanotubes and Ferrocenyl-Carnosine for Electrochemical Sensing of Hg(II).

The study reports the use of nanoassembly based on cationic cyclodextrin carbon nanotubes (CNT-CDs) and ferrocenylcarnosine (FcCAR) for electrochemical sensing of Hg(II) in aqueous solution. β-cyclodextrins (CDs) were grafted onto CNTs by a click chemistry reaction between heptakis-(6-azido-6-deoxy)-β-cyclodextrin and alkyne-terminated CNTs. The cationic amine groups on the CD units were produced by the subsequent reduction of the residual nitrogen groups.

Thermodynamic and voltammetric study on carnosine and ferrocenyl-carnosine.

A potentiometric study on the interactions of L-carnosine (CAR) (2-[(3-aminopropanoyl)amino]-3-(1-imidazol-5-yl)propanoic acid) with two toxic metal cations, Hg and Cd, is reported here. The elucidation of the metal (M)-CAR interactions in aqueous solution highlighted the speciation model for each system, the dependence of the formation constants of the complex species on ionic strength (0.15 ≤ /mol L ≤ 1) and temperature (288.

Cyclodextrin polymer clean-up method for the detection of ciguatoxins in fish with cell-based assays.

Ciguatoxins (CTXs) are marine toxins produced by microalgae of the genera Gambierdiscus and Fukuyoa, which are transferred through the food webs, reaching humans and causing a poisoning known as ciguatera. The cell-based assay (CBA) is commonly used for their detection because of its high sensitivity and the provided toxicological information. However, matrix effects may interfere in the CBA.

Supramolecular Complexes of Plant Neurotoxin Veratridine with Cyclodextrins and Their Antidote-like Effect on Neuro-2a Cell Viability.

Veratridine (VTD) is a plant neurotoxin that acts by blocking the voltage-gated sodium channels (VGSC) of cell membranes. Symptoms of VTD intoxication include intense nausea, hypotension, arrhythmia, and loss of consciousness. The treatment for the intoxication is mainly focused on treating the symptoms, meaning there is no specific antidote against VTD.

Cyclodextrin polymers as passive sampling materials for lipophilic marine toxins in Prorocentrum lima cultures and a Dinophysis sacculus bloom in the NW Mediterranean Sea.

Cyclodextrins, cyclic oligomers that form a conical structure with an internal cavity, are proposed as new and sustainable materials for passive sampling of lipophilic marine toxins. Two applicability scenarios have been tested. First, disks containing β-cyclodextrin-hexamethylene diisocyanate (β-CD-HDI) and β-cyclodextrin-epichlorohydrin (β-CD-EPI) polymers were immersed in Prorocentrum lima cultures for different days (2, 12 and 40).

Amperometric biosensor for glyphosate based on the inhibition of tyrosinase conjugated to carbon nano-onions in a chitosan matrix on a screen-printed electrode.

Glyphosate [N-(phosphonomethyl)glycine] is the most frequently used herbicide to date. Due to its indiscriminate use, it has become a globally occurring pollutant of surface waters. A biosensor for glyphosate is described here that consists of a carbon nano-onion/tyrosinase conjugate immobilized in a chitosan matrix on a screen-printed electrode.

Development of highly sensitive IgA immunosensors based on co-electropolymerized L-DOPA/dopamine carbon nano-onion modified electrodes.

The development of versatile platforms to construct novel and sensitive immunosensors is nowadays an intense research field. Nanomaterials and polymers are often combined to fabricate new platforms to immobilize capture antibodies. Here we evaluate for the first time the co-electropolymerization of dopamine (DA) and L-3,4-dihydroxyphenylalanine (L-DOPA) on carbon nano-onion (CNO) modified electrodes as versatile platform to develop electrochemical immunosensors.

Kinetic, spectroscopic and computational docking study of the inhibitory effect of the pesticides 2,4,5-T, 2,4-D and glyphosate on the diphenolase activity of mushroom tyrosinase.

The inhibitory effect of 2,4,5-T, 2,4-D, glyphosate and paraquat on the diphenolase activity of mushroom tyrosinase for oxidation of L-DOPA has been investigated by kinetic measurements, fluorescence spectroscopy and computational docking analysis. 2,4,5-T and 2,4-D inhibit the diphenolase activity of the enzyme following a competitive mechanism, while glyphosate is a mixed inhibitor according to Lineweaver-Burk kinetic analysis. The inhibitory activity follows the order glyphosate >2,4,5-T > 2,4-D with IC values of 65, 90 and 106 μM, respectively.

Preparation and characterization of alkaline phosphatase, horseradish peroxidase, and glucose oxidase conjugates with carboxylated carbon nano-onions.

Carbon nanomaterials have emerged as suitable supports for enzyme immobilization and stabilization due to their inherently large surface area, high electrical conductivity, chemical stability, and mechanical strength. In this paper, carbon nano-onions (CNOs) were used as supports to immobilize alkaline phosphatase, horseradish peroxidase, and glucose oxidase. CNOs were first functionalized by oxidation to generate carboxylic groups on the surface followed by the covalent linking of using a soluble carbodiimide as coupling agent.

Site-directed introduction of disulfide groups on antibodies for highly sensitive immunosensors.

The interface between the sample and the transducer surface is critical to the performance of a biosensor. In this work, we compared different strategies for covalent self-assembly of antibodies onto bare gold substrates by introducing disulfide groups into the immunoglobulin structure, which acted as anchor molecules able to chemisorb spontaneously onto clean gold surfaces. The disulfide moieties were chemically introduced to the antibody via the primary amines, carboxylic acids, and carbohydrates present in its structure.

Supramolecular biosensors based on electropolymerised pyrrole-cyclodextrin modified surfaces for antibody detection.

The self-assembly of an adamantane-appended polymer bearing an antigen fragment on a polypyrrole-cyclodextrin modified surface provides a highly sensitive immunosensor with low limits of detection for celiac disease related targets. The pyrrole-carboxylic acid films were formed on the surface of gold electrodes by electropolymerisation and followed by covalent attachment of cyclodextrin units. Surface plasmon resonance measurements confirmed the role of the host/guest interactions between adamantane moieties and β-cyclodextrin hosts in the formation of the supramolecular sensor interface.

Reactive Carbon Nano-Onion Modified Glassy Carbon Surfaces as DNA Sensors for Human Papillomavirus Oncogene Detection with Enhanced Sensitivity.

Glassy carbon electrodes were modified with small carbon nano-onions (CNOs) and activated by electrografting of diazonium salts bearing terminal carboxylic acid and maleimide groups. The CNO-modified surfaces were characterized by ESEM and AFM microscopy as well as by electrochemical techniques. The modified electrodes were used for the amperometric detection of a model DNA target sequence associated with the human papillomavirus by immobilizing short recognition sequences by amidation or thiol-maleimide reactions.

Bleed-to-read disposable microsystems for the genetic and serological analysis of celiac disease markers with amperometric detection.

Celiac disease is an auto-immune disorder induced by ingestion of gluten in genetically predisposed individuals. Its diagnostics is more accurate using a combination of immunologic and genetic tests to detect of high levels of certain auto-antibodies and the presence human leukocyte antigen HLA-DQ2 or HLA-DQ8 genetic markers. In this work, we report the design and testing of automated microsystems combining sample treatment, storage, fluidic transport, and detection in a single platform able to carry out genetic or serologic analysis for detection of celiac disease markers.

Supramolecular solubilization of cyclodextrin-modified carbon nano-onions by host-guest interactions.

Small carbon nano-onions (CNOs, 6-12 shells) were prepared in high yields and functionalized with carboxylic groups by chemical oxidation and reacted with βCD-NH2 to yield CNOs decorated with βCDs. A biocompatibile dextran polymer with graphted ferrocene groups was employed for the supramolecular self-assembly on the βCD-CNO surfaces. The βCDs act as hosts and the polymer ferrocene groups as guests (Fc-Dex) by the formation of inclusion complexes.

Peroxidase-encapsulated cyclodextrin nanosponge immunoconjugates as a signal enhancement tool in optical and electrochemical assays.

Cyclodextrin nanosponges bearing carboxylate groups have been prepared by crosslinking β-cyclodextrin with pyromellitic dianhydride to form a carboxylic acid terminated nanoporous material. The surface of the particles was covalently modified with an anti-IgG antibody and then loaded with horseradish peroxidase. The structures of unmodified and protein modified nanosponge particles were investigated by Raman spectroscopy and imaging methods.

A compact hybrid-multiplexed potentiostat for real-time electrochemical biosensing applications.

The architecture and design of a compact, multichannel, hybrid-multiplexed potentiostat for performing electrochemical measurements on continuously-biased electrode arrays is presented. The proposed architecture utilises a combination of sequential and parallel measurements, to enable high performance whilst keeping the system low-cost and compact. The accuracy of the signal readout is maintained by following a special multiplexing approach, which ensures the continuous biasing of all the working electrodes of an array.

Evaluation of techniques for generation of single-stranded DNA for quantitative detection.

A simple and efficient method for the generation of clean single-stranded DNA (ssDNA) with a high recovery and purity from a double-stranded polymerase chain reaction (PCR) product is required for nucleic acid sensing and microarray applications. Currently, the most widely used technique is thermal denaturation due to its simplicity and low cost, but this technique has drawbacks in terms of recovery and reproducibility. The work presented here compares this technique with alternative approaches for ssDNA generation exploiting affinity magnetic separation and exonuclease digestion.

Spectroscopic and atomic force microscopy characterization of the electrografting of 3,5-bis(4-diazophenoxy)benzoic acid on gold surfaces.

The synthesis of a bipodal diazonium salt, 3,5-bis(4-diazophenoxy)benzoic acid, and the study of its electrochemical deposition on gold surfaces is presented. The presence of the organic layer on the gold surface was characterized using atomic force microscopy and X-ray photoelectron spectroscopy, demonstrating the presence of phenyl groups, indicative of the grafted layer as well as the formation of multilayers, dependent on the electrografting conditions.

Highly sensitive colorimetric enzyme-linked oligonucleotide assay based on cyclodextrin-modified polymeric surfaces.

In this paper, we describe the development of an enzyme-linked oligonucleotide assay for the detection of a human leukocyte antigen allele associated with celiac disease based on cyclodextrin-modified polymeric surfaces. The surface of maleimide-pre-coated plates was modified with a layer of thiolated cyclodextrin polymer and used for the supramolecular capture of adamantane or ferrocene-modified carboxymethylcellulose polymers bearing DNA probes. The assay was optimised in terms of incubation time, temperature, and surface chemistry and applied to the highly sensitive and selective detection of HLA sequences with a limit of detection of 0.

Electrochemical genosensor array for the simultaneous detection of multiple high-risk human papillomavirus sequences in clinical samples.

An electrochemical genosensor array for the simultaneous detection of three high-risk human papillomavirus (HPV) DNA sequences, HPV16, 18 and 45, exhibiting high sensitivity and selectivity is presented. The electrodes of a 4×4 array were modified via co-immobilization of a 1:100 (mol/mol) mixture of a thiolated probe and an oligoethyleneglycol-terminated bipodal thiol. Detection of synthetic and PCR products was carried out in a sandwich type format, with the target hybridized between a surface immobilized probe and a horseradish peroxidase-labelled secondary reporter probe.

A bienzymatic amperometric immunosensor exploiting supramolecular construction for ultrasensitive protein detection.

Self-assembly of a ferrocene-appended polymer bearing an antigen fragment and lactate oxidase on a cyclodextrin-modified surface provides a highly sensitive, easy-to-operate and self-sufficient immunosensor.

Amperometric detection of antibodies in serum: performance of self-assembled cyclodextrin/cellulose polymer interfaces as antigen carriers.

A bifunctionalised carboxymethyl-cellulose polymer bearing adamantane units and an antigenic fragment forms a highly stable interfacial complex with a βCD-containing surface. This allows the highly sensitive detection of antibodies using an amperometric immunosensor.

Detection of antigliadin autoantibodies in celiac patient samples using a cyclodextrin-based supramolecular biosensor.

Celiac disease is a condition associated with the ingestion of gluten by genetically susceptible individuals. Measurement of serum antigliadin antibodies is a diagnostic tool also used as a means of monitoring a patient's compliance to a gluten-free diet. In this work, we demonstrate the applicability of an electrochemical supramolecular platform based on cyclodextrin-modified gold surfaces to detect antigliadin antibodies in real serum samples.