A novel amperometric hydrogen peroxide biosensor based on electrospun Hb–collagen composite

Hemoglobin–metal2+ phosphate nanoflowers with enhanced peroxidase-like activities and their performance in the visual detection of hydrogen peroxide

Hemoglobin (Hgb)–metal²⁺ phosphate nanoflowers (Hgb–X²⁺-Nfs) were synthesized using Co²⁺, Zn²⁺, Ca²⁺, and Fe²⁺ separately as inorganic components, to generate a visual hydrogen peroxide (H₂O₂) biosensor for the first time.

Nature-derived materials for the fabrication of functional biodevices

Nature provides an incredible source of inspiration, structural concepts, and materials toward applications to improve the lives of people around the world, while preserving ecosystems, and addressing environmental sustainability. In particular, materials derived from animal and plant sources can provide low-cost, renewable building blocks for such applications. Nature-derived materials are of interest for their properties of biodegradability, bioconformability, biorecognition, self-repair, and stimuli response. While long used in tissue engineering and regenerative medicine, their use in functional devices such as (bio)electronics, sensors, and optical systems for healthcare and biomonitoring is finding increasing attention. The objective of this review is to cover the varied nature derived and sourced materials currently used in active biodevices and components that possess electrical or electronic behavior. We discuss materials ranging from proteins and polypeptides such as silk and collagen, polysaccharides including chitin and cellulose, to seaweed derived biomaterials, and DNA. These materials may be used as passive substrates or support architectures and often, as the functional elements either by themselves or as biocomposites. We further discuss natural pigments such as melanin and indigo that serve as active elements in devices. Increasingly, combinations of different biomaterials are being used to address the challenges of fabrication and performance in human monitoring or medicine. Finally, this review gives perspectives on the sourcing, processing, degradation, and biocompatibility of these materials. This rapidly growing multidisciplinary area of research will be advanced by a systematic understanding of nature-inspired materials and design concepts in (bio)electronic devices.

Peptide-protein based nanofibers in pharmaceutical and biomedical applications

In recent years, electrospun fibers have found wide use, especially in pharmaceutical area and biomedical applications, related to the various advantages such as high surface-volume ratio, high solubility and having wide usage areas they have provided. Biocompatible and biodegradable fibers can be obtained by using peptide-protein structures of plant and animal derived along with synthetic polymers. Plant-derived proteins used in nanofiber production can be listed as, zein, soy protein, and gluten and animal derived proteins can be listed as casein, silk fibroin, hemoglobine, bovine serum albumin, elastin, collagen, gelatin, and keratin. Plant and animal proteins and synthetic peptides used in electrospun fiber production were reviewed in detail. In addition, the important physical properties of these materials for the electrospinning process and their use in pharmaceutical and biomedical areas were discussed.

A magnetic electrode modified with hemoglobin for determination of hydrogen peroxide: distinctly improved response by applying a magnetic field

A facile and highly sensitive biosensor was developed for the determination of hydrogen peroxide (H₂O₂) via electrochemical catalytic reduction of H₂O₂ by hemoglobin (Hb). Hb was enriched and immobilized simply in a chitosan (Chit) membrane on a magnetic electrode to construct an enzyme-like biosensor. The biosensor catalyzes the electrochemical reduction of H₂O₂ under an external magnetic field. The response improved roughly twice as Hb was adsorbed by Chit in an alkaline medium. The response of the biosensor under the magnetic field increased by 16% owing to the paramagnetism of Hb. The effect of pH values on Hb adsorption by Chit, as well as the effect of an external magnetic field on Hb configuration were investigated by UV-vis spectroscopy. The reduction peak current has linear and log-linear relationships with H₂O₂ concentration in the range of 5-250 μmol∙L^-1 and 0.01-1 μmol∙L^-1, respectively. The detection limit was 0.003 μmol∙L^-1, with a good sensitivity of 0.227 μA∙μM^-1∙cm^-2. The biosensor was successfully applied to the determination of H₂O₂ in milk samples and in disinfectant solutions. Recoveries ranged from 96.3 to 105.4%, and from 95.3 to 107.7%, respectively. Graphical abstractConstruction of the biosensor, and principle of H₂O₂ determination based on Hb bioelectrocatalysis.

Sinapic acid-loaded chitosan nanoparticles in polycaprolactone electrospun fibers for bone regeneration in vitro and in vivo

Sinapic acid (SA) is a plant-derived phenolic compound known for its multiple biological properties, but its role in the promotion of bone formation is not yet well-studied. Moreover, the delivery of SA is hindered by its complex hydrophobic nature, limiting its bioavailability. In this study, we fabricated a drug delivery system using chitosan nanoparticles (nCS) loaded with SA at different concentrations. These were incorporated into polycaprolactone (PCL) fibers via an electrospinning method. nCS loaded with 50 μM SA in PCL fibers promoted osteoblast differentiation. Furthermore, SA treatment activated the osteogenesis signaling pathways in mouse mesenchymal stem cells. A critical-sized rat calvarial bone defect model system identified that the inclusion of SA into PCL/nCS fibers accelerated bone formation. Collectively, these data suggest that SA promoted osteoblast differentiation in vitro and bone formation in vivo, possibly by activating the TGF-β1/BMP/Smads/Runx2 signaling pathways, suggesting SA might have therapeutic benefits in bone regeneration.

An amperometric H2O2 biosensor based on hemoglobin nanoparticles immobilized on to a gold electrode

The nanoparticles (NPs) of hemoglobin (Hb) were prepared by desolvation method and characterized by transmission electron microscopy (TEM), UV spectroscopy and Fourier-transform IR (FTIR) spectroscopy. An amperometric H₂O₂ biosensor was constructed by immobilizing HbNPs covalently on to a polycrystalline Au electrode (AuE). HbNPs/AuE were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) before and after immobilization of HbNPs. The HbNPs/AuE showed optimum response within 2.5 s at pH 6.5 in 0.1 M sodium phosphate buffer (PB) containing 100 μM H₂O₂ at 30°C, when operated at –0.2 V against Ag/AgCl. The HbNPs/AuE exhibited V_max of 5.161 ± 0.1 μA cm⁻² with apparent Michaelis-Menten constant (K_m) of 0.1 ± 0.01 mM. The biosensor showed lower detection limit (1.0 μM), high sensitivity (129 ± 0.25 μA cm⁻² mM⁻¹) and wider linear range (1.0–1200 μM) for H₂O₂ as compared with earlier biosensors. The analytical recoveries of added H₂O₂ in serum (0.5 and 1.0 μM) were 97.77 and 98.01% respectively, within and between batch coefficients of variation (CV) were 3.16 and 3.36% respectively. There was a good correlation between sera H₂O₂ values obtained by standard enzymic colorimetric method and the present biosensor (correlation coefficient, R² =0.99). The biosensor measured H₂O₂ level in sera of apparently healthy subjects and persons suffering from diabetes type II. The HbNPs/AuE lost 10% of its initial activity after 90 days of regular use, when stored dry at 4°C.

Controlled release from thermo-sensitive PNVCL-co-MAA electrospun nanofibers: The effects of hydrophilicity/hydrophobicity of a drug

The thermo-sensitive copolymer poly(N-vinylcaprolactam-co-methacrylic acid) (PNVCL-co-MAA) was synthesized by free radical polymerization and the resulting nanofibers were fabricated using an electrospinning process. The molecular weight of the copolymer was adjusted by varying the content of methacrylic acid (MAA) while keeping that of N-vinylcaprolactam (NVCL) constant. Hydrophilic captopril and hydrophobic ketoprofen were used as model drugs, and PNVCL-co-MAA nanofibers were used as the drug carrier to investigate the effects of drug on its release properties from nanofibers at different temperatures. The results showed that slow release over several hours was observed at 40°C (above the lower critical solution temperature (LCST) of PNVCL-co-MAA), while the drugs exhibited a burst release of several seconds at 20°C (below the LCST). Drug release slowed with increasing content of the hydrophobic monomer NVCL. The hydrophilic captopril was released at a higher rate than the hydrophobic ketoprofen. The drug release characteristics were dependent on the temperature, the portion of hydrophilic groups and hydrophobic groups in the copolymer and hydrophilicity/hydrophobicity of drug. Study on the mechanism of release showed that Korsmeyer-Peppas model as a major drug release mechanism. Given these results, the PNVCL-co-MAA copolymers are proposed to have useful applications in intellectual drug delivery systems.

Autism Spectrum Disorders: Translating human deficits into mouse behavior

Autism Spectrum Disorders are a heterogeneous group of neurodevelopmental disorders, with rising incidence but little effective therapeutic intervention available. Currently two main clinical features are described to diagnose ASDs: impaired social interaction and communication, and repetitive behaviors. Much work has focused on understanding underlying causes of ASD by generating animal models of the disease, in the hope of discovering signaling pathways and cellular targets for drug intervention. Here we review how ASD behavioral phenotypes can be modeled in the mouse, the most common animal model currently in use in this field, and discuss examples of genetic mouse models of ASD with behavioral features that recapitulate various symptoms of ASD.

Magnetic silver hybrid nanoparticles for surface-enhanced resonance Raman spectroscopic detection and decontamination of small toxic molecules

Magnetic hybrid assemblies of Ag and Fe3O4 nanoparticles with biocompatibly immobilized myoglobin (Mb) were designed to detect and capture toxic targets (NO2-, CN-, and H2O2). Mb was covalently attached to chitosan-coated magnetic silver hybrid nanoparticles (M-Ag-C) via glutaraldehyde that serves as a linker for the amine groups of Mb and chitosan. As verified by surface-enhanced resonance Raman (SERR) spectroscopy, this immobilization strategy preserves the native structure of the bound Mb as well as the binding affinity for small molecules. On the basis of characteristic spectral markers, binding of NO2-, CN-, and H2O2 could be monitored and quantified, demonstrating the high sensitivity of this approach with detection limits of 1 nM for nitrite, 0.2 μM for cyanide, and 10 nM for H2O2. Owing to the magnetic properties, these particles were collected by an external magnet to achieve an efficient decontamination of the solutions as demonstrated by SERR spectroscopy. Thus, the present approach combines the highly sensitive analytical potential of SERR spectroscopy with an easy approach for decontamination of aqueous solutions with potential applications in food and in environmental and medical safety control.