Mitigation of acrylamide formation in wood oven baked pizza base using wholemeal and refined wheat flour with low free asparagine content: considerations on fibre intake and starch digestibility.

BACKGROUND: In wheat-derived bakery products, the quantity of free asparagine (fAsn) has been identified as a key factor in acrylamide (AA) formation. Based on this assumption, four varieties of common wheat (Triticum aestivum L.), Stromboli, Montecarlo, Sothys and Cosmic, selected for their different fAsn content inside the grain, were studied to evaluate their potential in the production of pizza with reduced AA levels. To this purpose, wholemeal and refined flours were obtained from each variety. RESULTS: The fAsn content ranged from 0.25 to 3.30 mmol kg-1, with higher values for wholemeal flours which also showed greater amount of ash, fibre and damaged starch than refined wheat flours. All types of flours were separately used to produce wood oven baked pizza base, according to the Traditional Speciality Guaranteed EU Regulation (97/2010). AA reduction in the range 47-68% was found for all the selected wheat cultivars, compared with a commercial flour, with significantly lower values registered when refined flour was used. Moreover, refined leavened dough samples showed decreased levels of fAsn and reducing sugars due to the fermentation activity of yeasts. Furthermore, it was confirmed that pizza made with wholemeal flours exhibited lower rapidly digestible starch (RDS) and rapidly available glucose (RAG) values compared to that prepared with the refined flour. CONCLUSION: This study clearly shows that a reduced asparagine content in wheat flour is a key factor in the mitigation of AA formation in pizza base. Unfortunately, at the same time, it is highlighted how it is necessary to sacrifice the beneficial effects of fibre intake, such as lowering the glycaemic index, in order to reduce AA. © 2024 Society of Chemical Industry.

Electrochemical aptasensor based on anisotropically modified (Janus-type) gold nanoparticles for determination of C-reactive protein.

Novel Janus nanoparticles based on Au colloids anisotropically modified with polyamidoamine dendrons were prepared though a masking/toposelective modification approach. These nanomaterials were further functionalized with horseradish peroxidase on the dendritic face and provided on the opposite metal surface with a ssDNA aptamer for C-reactive protein (CRP). The resulting nanoparticles were employed as biorecognition/signaling elements to construct an amperometric aptasensor with sandwich-type architecture for the specific detection of this cardiac biomarker. To do this, screen-printed carbon electrodes modified with electrodeposited Au nanoparticles and functionalized with anti-CRP aptamers were used as transduction interface. The aptasensor was employed for the amperometric detection of CRP (working potential: - 200 mV vs pseudo-Ag/AgCl) in the broad range from 10 pg·mL-1 to 1.0 ng·mL-1 with a detection limit of 3.1 pg·mL-1. This electroanalytical device also showed good specificity, reproducibility (RSD = 9.8%, n = 10), and stability and was useful to quantify CRP in reconstituted human serum samples, with a RSD of 13.3%.

Electrochemical biosensors based on nucleic acid aptamers.

During recent decades, nucleic acid aptamers have emerged as powerful biological recognition elements for electrochemical affinity biosensors. These bioreceptors emulate or improve on antibody-based biosensors because of their excellent characteristics as bioreceptors, including limitless selection capacity for a large variety of analytes, easy and cost-effective production, high stability and reproducibility, simple chemical modification, stable and oriented immobilization on electrode surfaces, enhanced target affinity and selectivity, and possibility to design them in target-sensitive 3D folded structures. This review provides an overview of the state of the art of electrochemical aptasensor technology, focusing on novel aptamer-based electroanalytical assay configurations and providing examples to illustrate the different possibilities. Future prospects for this technology are also discussed. Graphical abstract.

A Versatile New Paradigm for the Design of Optical Nanosensors Based on Enzyme-Mediated Detachment of Labeled Reporters: The Example of Urea Detection.

Here, a new bio-inspired nanoarchitectonics approach for the design of optical probes is presented. It is based on nanodevices that combine 1) an enzymatic receptor subunit, 2) a signaling subunit (consisting of a labeled reporter attached to a silica surface), and 3) a mechanism of communication between the two sites based on the production of chemical messengers by the enzymatic subunit, which induces the detachment of the reporter molecules from the silica surface. As a proof of concept, a urea nanosensor based on the release of Alexa-Fluor-647-labeled oligonucleotide from enzyme-functionalized Janus gold-mesoporous-silica nanoparticles (Au-MSNPs) was developed. The Janus particles were functionalized on the silica face with amino groups to which the labeled oligonucleotides were attached by electrostatic interactions, whereas the gold face was used for grafting urease enzymes. The nanodevice was able to release the fluorescent oligonucleotide through the enzyme-mediated hydrolysis of urea to ammonia and the subsequent deprotonation of amino groups on the silica face. This simple nanodevice was applied for the fluorometric detection of urea in real human blood samples and for the identification of adulterated milk. Given the large variety of enzymes and reporter species that could be combined, this is a general new paradigm that could be applied to the design of a number of optical probes for the detection of target analytes.

Janus Gold Nanostars-Mesoporous Silica Nanoparticles for NIR-Light-Triggered Drug Delivery.

Janus gold nanostar-mesoporous silica nanoparticle (AuNSt-MSNP) nanodevices able to release an entrapped payload upon irradiation with near infrared (NIR) light were prepared and characterized. The AuNSt surface was functionalized with a thiolated photolabile molecule (5), whereas the mesoporous silica face was loaded with a model drug (doxorubicin) and capped with proton-responsive benzimidazole-ß-cyclodextrin supramolecular gatekeepers (N 1). Upon irradiation with NIR-light, the photolabile compound 5 photodissociated, resulting in the formation of succinic acid, which induced the opening of the gatekeeper and cargo delivery. In the overall mechanism, the gold surface acts as a photochemical transducer capable of transforming the NIR-light input into a chemical messenger (succinic acid) that opens the supramolecular nanovalve. The prepared hybrid nanoparticles were non-cytotoxic to HeLa cells, until they were irradiated with a NIR laser, which led to intracellular doxorubicin release and hyperthermia. This induced a remarkable reduction in HeLa cells viability.

An Interactive Model of Communication between Abiotic Nanodevices and Microorganisms.

The construction of communication models at the micro-/nanoscale involving abiotic nanodevices and living organisms has the potential to open a wide range of applications in biomedical and communication technologies. However, this area remains almost unexplored. Herein, we report, as a proof of concept, a stimuli-responsive interactive paradigm of communication between yeasts (as a model microorganism) and enzyme-controlled Janus Au-mesoporous silica nanoparticles. In the presence of the stimulus, the information flows from the microorganism to the nanodevice, and then returns from the nanodevice to the microorganism as a feedback.

Disposable amperometric immunosensor for Saccharomyces cerevisiae based on carboxylated graphene oxide-modified electrodes.

A sensitive and disposable amperometric immunosensor for Saccharomyces cerevisiae was constructed by using carbon screen-printed electrodes modified with propionic acid-functionalized graphene oxide as transduction element. The affinity-based biosensing interface was assembled by covalent immobilization of a specific polyclonal antibody on the carboxylate-enriched electrode surface via a water-soluble carbodiimide/N-hydroxysuccinimide coupling approach. A concanavalin A-peroxidase conjugate was further used as signaling element. The immunosensor allowed the amperometric detection of the yeast in buffer solution and white wine samples in the range of 10-107 CFU/mL. This electroanalytical device also exhibited low detection limit and high selectivity, reproducibility, and storage stability. The immunosensor was successfully validated in spiked white wine samples.

Self-Regulated Glucose-Sensitive Neoglycoenzyme-Capped Mesoporous Silica Nanoparticles for Insulin Delivery.

We describe herein the preparation of glucose-sensitive capped mesoporous silica nanoparticles for insulin delivery. The new material consists of an expanded-pore nanometric silica support grafted with 1-propyl-1-H-benzimidazole groups, loaded with fluorescein isothiocyanate-labeled insulin (FITC-Ins) and capped by the formation of inclusion complexes between cyclodextrin-modified glucose oxidase (CD-GOx) and the benzimidazole groups grafted on the mesoporous support. Insulin delivery from the gated material in simulated blood plasma was assessed upon addition of glucose. Glucose is transformed by GOx into gluconic acid, which promoted the dethreading of the benzimidazole-CD-GOx inclusion complexes, allowing cargo release. Small quantities of this support would be needed to release the amount of insulin necessary to decrease diabetic blood glucose concentrations to regular levels.

Enzyme-Controlled Nanodevice for Acetylcholine-Triggered Cargo Delivery Based on Janus Au-Mesoporous Silica Nanoparticles.

This work reports a new gated nanodevice for acetylcholine-triggered cargo delivery. We prepared and characterized Janus Au-mesoporous silica nanoparticles functionalized with acetylcholinesterase on the Au face and with supramolecular ß-cyclodextrin:benzimidazole inclusion complexes as caps on the mesoporous silica face. The nanodevice is able to selectively deliver the cargo in the presence of acetylcholine via enzyme-mediated acetylcholine hydrolysis, locally lowering the pH and opening the supramolecular gate. Given the key role played by ACh and its relation with Parkinson's disease and other nervous system diseases, we believe that these findings could help design new therapeutic strategies.

Disposable electrochemical immunosensor for Brettanomyces bruxellensis based on nanogold-reduced graphene oxide hybrid nanomaterial.

The assembly of a novel disposable amperometric immunosensor for the detection of the red wine spoilage yeast Brettanomyces bruxellensis is reported. The nanostructured sensing interface was prepared by first coating carbon screen printed electrodes with a gold nanoparticles-reduced graphene oxide hybrid nanomaterial, which was then modified with 3-mercaptopropionic acid to further immobilize specific antibodies for B. bruxellensis via a carbodiimide-coupling reaction. The functionalized electrode allowed the amperometric detection of B. bruxellensis in buffered solutions and red wine samples in the range of 10-106 CFU/mL and 102-106 CFU/mL, with low detection limits of 8 CFU/mL and 56 CFU/mL, respectively. The electrochemical immunosensor also exhibited high reproducibility, selectivity, and storage stability. Graphical abstract A novel disposable electrochemical immunosensor for the detection of the red wine spoilage yeast B. bruxellensis.

Novel reduced graphene oxide-glycol chitosan nanohybrid for the assembly of an amperometric enzyme biosensor for phenols.

A novel water-soluble graphene derivative was prepared from graphene oxide via a two-step modification approach. Graphene oxide was first functionalised with reactive epoxy groups by covalent modification with (3-glycidyloxypropyl)trimethoxysilane and further cross-linked with glycol chitosan. This graphene derivative was characterized using different microscopy and physicochemical methods and employed as a coating material for a glassy carbon electrode. The nanostructured surface was used as a support for the covalent immobilization of the enzyme laccase through cross-linking with glutaraldehyde. The enzyme electrode was tested for the amperometric detection of different phenolic compounds, which displayed excellent analytical behaviour toward catechol with a linear range of response from 200 nM to 15 µM, sensitivity of 93 mA M(-1) cm(-2), and low detection limit of 76 nM. The enzyme biosensor showed high stability when stored at 4 °C under dry conditions and was successfully employed to quantify the total phenolic compounds in commercial herbal tea samples.

Label-free electrochemical genosensor based on mesoporous silica thin film.

A novel label-free electrochemical strategy for nucleic acid detection was developed by using gold electrodes coated with mesoporous silica thin films as sensing interface. The biosensing approach relies on the covalent attachment of a capture DNA probe on the surface of the silica nanopores and further hybridization with its complementary target oligonucleotide sequence, causing a diffusion hindering of an Fe(CN)6 (3-/4-) electrochemical probe through the nanochannels of the mesoporous film. This DNA-mesoporous silica thin film-modified electrodes allowed sensitive (91.7 A/M) and rapid (45 min) detection of low nanomolar levels of synthetic target DNA (25 fmol) and were successfully employed to quantify the endogenous content of Escherichia coli 16S ribosomal RNA (rRNA) directly in raw bacterial lysate samples without isolation or purification steps. Moreover, the 1-month stability demonstrated by these biosensing devices enables their advanced preparation and storage, as desired for practical real-life applications. Graphical abstract Mesoporous silica thin films as scaffolds for the development of novel label-free electrochemical genosensors to perform selective, sensitive and rapid detection of target oligonucleotide sequences. Application towards E. coli determination.

Dual functional graphene derivative-based electrochemical platforms for detection of the TP53 gene with single nucleotide polymorphism selectivity in biological samples.

Novel disposable electrochemical DNA sensors were prepared for the detection of a target DNA sequence on the p53 tumor suppressor (TP53) gene. The electrochemical platform consisted of screen-printed carbon electrodes (SPCEs) functionalized with a water-soluble reduced graphene oxide-carboxymethylcellulose (rGO-CMC) hybrid nanomaterial. Two different configurations involving hairpin specific capture probes of different length covalently immobilized through carbodiimide chemistry on the surface of rGO-CMC-modified SPCEs were implemented and compared. Upon hybridization, a streptavidin-peroxidase (Strep-HRP) conjugate was employed as an electrochemical indicator. Hybridization was monitored by recording the amperometric responses measured at -0.10 V (vs an Ag pseudo-reference electrode) upon the addition of 3,3',5,5'-tetramethylbenzidine (TMB) as a redox mediator and H2O2 as an enzyme substrate. The implemented DNA platforms allow single nucleotide polymorphism (SNP) discrimination in cDNAs from human breast cancer cell lines, which makes such platforms excellent as new diagnosis tools in clinical analysis.

First Occurrence of Tetrazines in Aqueous Solution: Electrochemistry and Fluorescence.

The photophysical and electrochemical properties of tetrazines substituted by linear 2,3-naphtalimide antennas and/or adamantane groups specifically dedicated to host-guest interactions with cyclodextrins are studied both in organic and aqueous media. In acetonitrile solvent, the reduction potential of tetrazine leading to the anion radical is shifted, depending on the electron-withdrawing power of the substituent of the tetrazines. Due to the hydrophobic character of these compounds, their solubilization in aqueous solution is achieved successively in presence of either ß-cyclodextrins or gold nanoparticules modified by ß-cyclodextrins. We demonstrate that the formation of the inclusion compound tetrazine-cyclodextrin allows the solubilization of the tetrazines in aqueous solution. The supramolecular assemblies obtained in water retain tetrazine's emission properties, yielding a yellow fluorescence.

Toward the design of smart delivery systems controlled by integrated enzyme-based biocomputing ensembles.

We report herein the design of a smart delivery system in which cargo delivery from capped mesoporous silica (MS) nanoparticles is controlled by an integrated enzyme-based "control unit". The system consists of Janus-type nanoparticles having opposing Au and MS faces, functionalized with a pH-responsive ß-cyclodextrin-based supramolecular nanovalve on the MS surface and two effectors, glucose oxidase and esterase, immobilized on the Au face. The nanodevice behaves as an enzymatic logical OR operator which is selectively fueled by the presence of D-glucose and ethyl butyrate.

Self-propelled enzyme-controlled IR-mesoporous silica Janus nanomotor for smart delivery.

Here, we report the preparation of a novel Janus nanoparticle with opposite Ir and mesoporous silica nanoparticles through a partial surface masking with toposelective modification method. This nanomaterial was employed to construct an enzyme-powered nanomachine with self-propulsion properties for on-command delivery. The cargo-loaded nanoparticle was provided with a pH-sensitive gate and unit control at the mesoporous face by first attaching boronic acid residues and further immobilization of glucose oxidase through reversible boronic acid esters with the carbohydrate residues of the glycoenzyme. Addition of glucose leads to the enzymatic production of H2O2 and gluconic acid, being the first compound catalytically decomposed at the Ir nanoparticle face producing O2 and causing the nanomachine propulsion. Gluconic acid leads to a pH reduction at the nanomachine microenvironment causing the disruption of the gating mechanism with the subsequent cargo release. This work demonstrates that enzyme-mediated self-propulsion improved release efficiency being this nanomotor successfully employed for the smart release of Doxorubicin in HeLa cancer cells.

Enzyme-controlled sensing-actuating nanomachine based on Janus Au-mesoporous silica nanoparticles.

Novel Janus nanoparticles with Au and mesoporous silica faces on opposite sides were prepared using a Pickering emulsion template with paraffin wax as the oil phase. These anisotropic colloids were employed as integrated sensing-actuating nanomachines for enzyme-controlled stimuli-responsive cargo delivery. As a proof of concept, we demonstrated the successful use of the Janus colloids for controlled delivery of tris(2,2'-bipyridyl) ruthenium(II) chloride from the mesoporous silica face, which was grafted with pH-sensitive gatelike scaffoldings. The release was mediated by the on-demand catalytic decomposition of urea by urease, which was covalently immobilized on the Au face.

Supramolecular immobilization of glucose oxidase on gold coated with cyclodextrin-modified cysteamine core PAMAM G-4 dendron/Pt nanoparticles for mediatorless biosensor design.

Cysteamine core polyamidoamine G-4 dendron branched with ß-cyclodextrins was chemisorbed on the surface of Au electrodes and further coated with Pt nanoparticles. Adamantane-modified glucose oxidase was subsequently immobilized on the nanostructured electrode surface by supramolecular association. This enzyme electrode was used to construct a reagentless amperometric biosensor for glucose, making use of the electrochemical oxidation of H2O2 generated in the enzyme reaction. The amperometric response of the biosensor was rapid (6 s) and a linear function of glucose concentration between 5 and 705 µmol L(-1). The biosensor had a low detection limit of 2.0 µmol L(-1), sensitivity of 197 mA mol(-1) L cm(-2), and retained 94% of its initial response after storage for nine days at 4 °C.

An intercommunicated nanosystem for dual delivery.

Here, we describe the design of a novel particle-to-particle intercommunicated nanosystem for dual delivery, triggered by physical and chemical inputs. The nanosystem was composed of an Au-mesoporous silica Janus nanoparticle loaded with paracetamol, mechanized with light-sensitive supramolecular gates at the mesoporous face and functionalized on the metal surface with the enzyme acetylcholinesterase. The second component was a mesoporous silica nanoparticle loaded with rhodamine B and gated with thiol-sensitive ensembles. Upon irradiation of this nanosystem with a near-UV light laser, an analgesic drug was released from the Janus nanomachine due to disassembling of the photosensitive gating mechanism. Further addition of N-acetylthiocholine leads to the enzymatic production of thiocholine at the Janus nanomachine, thus acting as a "chemical messenger" causing the disruption of the gating mechanism at the second mesoporous silica nanoparticle with the subsequent dye release.

Electropolymerized network of polyamidoamine dendron-coated gold nanoparticles as novel nanostructured electrode surface for biosensor construction.

Polyfuntionalized gold nanoparticles were prepared by using 2-mercaptoethanesulfonic acid, p-aminothiophenol and cysteamine core polyamidoamine G-4 dendron as capping ligands. The nanoparticles were electropolymerized on a Au electrode surface through the formation of a bisaniline-cross-linked network. The enzyme tyrosinase was further crosslinked on this nanostructured matrix. The enzyme electrode, poised at -100 mV, was used for the amperometric quantification of cathecol. The biosensor showed a linear response from 50 nM to 10 µM cathecol, with a low detection limit of 20 nM and a sensitivity of 1.94 A M(-1) cm(2). The electrode retained 96% and 67% of its initial activity after 16 and 30 days of storage at 4 °C under dry conditions.