Conductive GelMA/alginate/polypyrrole/graphene hydrogel as a potential scaffold for cardiac tissue engineering; Physiochemical, mechanical, and biological evaluations.

Cardiac failure can be a life-threatening condition that, if left untreated, can have significant consequences. Functional hydrogel has emerged as a promising platform for cardiac tissue engineering. In the proposed study, gelatin methacrylate (GelMA) and alginate, as a primary matrix to maintain cell viability and proliferation, and polypyrrole and carboxyl-graphene, to improve mechanical and electrical properties, are thoroughly evaluated. Initially, a polymer blend of GelMA/Alginate (1:1) was prepared, and then the addition of 2-5 wt% of polypyrrole was evaluated. Next, the effect of incorporating graphene-carboxyl nanosheets (1, 2, and 3 wt%) within the optimized scaffold with 2 wt% polypyrrole was thoroughly studied. The electrical conductivity of the hydrogels was significantly enhanced from 0.0615 ± 0.007 S/cm in GelMA/alginate to 0.124 ± 0.04 S/cm with the addition of 5 wt% polypyrrole. Also, 3 wt% carboxyl graphene improved the electrical conductivity to 0.27 ± 0.09 S/cm. The compressive strength of carboxyl-graphene-containing hydrogel was in the range of 175 to 520 kPa, and tensile strength was 61 and 133 kPa. The simplicity and low-cost fabrication, tunable mechanical properties, optimal electrical conductivity, blood compatibility, and non-cytotoxicity of GelMA/alginate/polypyrrole/graphene biocomposite hydrogel is a promising construct for cardiac tissue engineering.

Enhanced antibacterial properties and magnetic removal of Fe3O4/fenugreek seed gum/silver nanocomposites for water treatment.

This study reports the synthesis, characterization, and antibacterial activity of a novel Fe3O4 nanocomposite coated with fenugreek seed gums and silver nanoparticles (AgNPs). To enhance the antibacterial properties of AgNPs and overcome the limitations of conventional methods for the production of three-component nanocomposites, a layer of natural polymer was used. Fenugreek seed gums (FSG) were used to coat Fe3O4 NPs to prevent their decomposition and to facilitate the release of silver nanoparticles in aqueous media. The Fe3O4/FSG/Ag nanocomposites were characterized and then the antibacterial activity of the nanocomposites was evaluated against two gram-negative and two gram-positive bacteria and compared with Fe3O4, Fe3O4/FSG, FSG, and AgNO3. The results showed that the Fe3O4/FSG/Ag nanocomposites had higher antibacterial activity than the other samples and could be easily removed from treated water by a powerful magnet without causing pollution in the environment. Overall, these findings suggest that the Fe3O4/FSG/Ag nanocomposites have potential applications in water treatment for their improved antibacterial properties and ease of removal.

Exploring the antibacterial potential of magnetite/Quince seed mucilage/Ag nanocomposite: Synthesis, characterization, and activity assessment.

In this study, we present a novel core-shell antibacterial agent designed for water disinfection purposes. The nanocomposite is synthesized by combining quince seed mucilage (QSM) as the shell material and Fe3O4 as the core material. The integration of antibacterial silver nanoparticles (Ag NPs) onto the QSM shell effectively prevents agglomeration of the Ag NPs, resulting in a larger contact surface area with bacteria and consequently exhibiting enhanced antibacterial activity. The incorporation of magnetic Fe3O4 NPs with a saturation magnetization of 55.2 emu·g-1 as the core allows for easy retrieval of the nanocomposites from the medium using a strong magnetic field, enabling their reusability. The Fe3O4/QSM/Ag nanocomposite is extensively characterized using XRD, FT-IR, VSM, DLS, FE-SEM, and TEM techniques. The characterization results confirm the successful synthesis of the nanocomposites, with an average particle size of 73 nm and no contamination or impurities detected. The nanocomposites exhibit superparamagnetic properties, with a saturated magnetization of 22.69 emu·g-1, ensuring facile separation from water. The antibacterial activity of the synthesized nanocomposite is evaluated using the disk diffusion method against both Gram-positive and Gram-negative bacteria. The results reveal excellent antibacterial efficacy, with minimum inhibition concentrations (MIC) of 0.8 mg·mL-1 against E. coli and S. typhimurium. Furthermore, the measurement of released silver ions in water using ICP-OES indicates a low concentration of remaining silver ions in the medium, highlighting the controlled release of antimicrobial agents. Overall, this study provides valuable insights into the development of advanced antibacterial agents for water disinfection applications, offering potential solutions to combat microbial contamination effectively.

Improving water treatment using a novel antibacterial kappa-carrageenan-coated magnetite decorated with silver nanoparticles.

In this study, we aimed to fabricate an enhanced antibacterial agent to act against pathogenic bacteria in aqueous environments. To achieve this, silver nanoparticles (AgNPs) were inlaid on a kappa-carrageenan (KC) base and coated on Fe3O4 magnetic cores (Fe3O4@KC@Ag). Superparamagnetic Fe3O4 nanoparticles were designed at the center of the composite nanostructure, allowing magnetic recovery from aqueous media in the presence of a magnet. The synthesized nanoconjugate was characterized in each step using XRD, FT-IR, EDX, FE-SEM, TEM, DLS, VSM, and disk-diffusion antibacterial method. Results show that the nanocomposite system is formed, while the magnetic properties remain practically stable. The agglomeration of the AgNPs was decreased by the trap-like function of KC coating, which resulted in an improved antibacterial activity for the Fe3O4@KC@Ag formulation. These findings suggest that Fe3O4@KC@Ag nanocomposites could be promising agents for combating bacterial infections in aqueous environments.

Antibacterial activity and shear bond strength of fiber-reinforced composites and bonding agents containing 0.5%, 1%, 2.5%, and 5% silver nanoparticles.

Background: Bonded composites may increase bacterial accumulation and caries formation risk. Therefore, assessment of methods to decrease bacterial activity around them would be valuable. The literature on the efficacy of adding silver nanoparticles to fiber-reinforced composite (FRC) or adding them to bonding agents in terms of their antibacterial activity and/or shear bond strength (SBS) is scarce. Thus, we aimed to assess the antibacterial activity of flowable composites and bonding agents containing various percentages of experimental silver nanoparticles (nanosilver) against S. mutans and to evaluate the SBS of FRC and bonding agents containing different amounts of nanosilver to enamel. Materials and Methods: In this preliminary study, 0% (control), 0.5%, 1%, 2.5%, and 5% nanosilver were added to flowable composite and bonding agent. Syntheses of nanosilver and nanosilver-incorporated composite specimens were approved using X-ray diffraction spectroscopy and scanning electron microscopy. Antibacterial effects of the produced materials on S. mutans were evaluated by colony count with serial dilution method (n = 7 groups × 10 [n = 70] specimens) and agar disc diffusion test (n = 6 groups × 5 [n = 30] composite specimens + n = 6 groups × 5 [n = 30] light-cured bonding + n = 6 groups × 5 [n = 30] uncured bonding) against negative control and cefotaxime antibiotic. Moreover, SBS values of various FRC blocks bonded to enamel using various bonding agents were measured (n = 9 groups × 6 [n = 54] human premolars). Data were analyzed using Kruskal-Wallis, Dunn, two-way analysis of variance, and Tukey's tests (α = 0.05). Results: Composite discs containing all concentrations of nanosilver reduced S. mutans colony counts (P < 0.05); bacterial growth was ceased at samples containing 2.5% and 5% of nanosilver. The reduction in the SBS of FRCs was significant only for 5% nanosilver (P < 0.05). Conclusion: Adding 0.5%, 1%, and 2.5% nanosilver to composite and 0.5% or 1% nanosilver to bonding agent led to a significant antibacterial behavior against S. mutans while not significantly affecting the SBS of FRC.

Gold Nano/Micro-Islands Overcome the Molecularly Imprinted Polymer Limitations to Achieve Ultrasensitive Protein Detection.

Here, we report on an electrochemical biosensor based on core-shell structure of gold nano/micro-islands (NMIs) and electropolymerized imprinted ortho-phenylenediamine (o-PD) for detection of heart-fatty acid binding protein (H-FABP). The shape and distribution of NMIs (the core) were tuned by controlled electrodeposition of gold on a thin layer of electrochemically reduced graphene oxide (ERGO). NMIs feature a large active surface area to achieve a low detection limit (2.29 fg mL-1, a sensitivity of 1.34 × 1013 µA mM-1) and a wide linear range of detection (1 fg mL-1 to 100 ng mL-1) in PBS. Facile template H-FABP removal from the layer (the shell) in less than 1 min, high specificity against interference from myoglobin and troponin T, great stability at ambient temperature, and rapidity in detection of H-FABP (approximately 30 s) are other advantages of this biomimetic biosensor. The electrochemical measurements in human serum, human plasma, and bovine serum showed acceptable recovery (between 91.1 ± 1.7 and 112.9 ± 2.1%) in comparison with the ELISA method. Moreover, the performance of the biosensor in clinical serum showed lower detection time and limit of detection against lateral flow assay (LFA) rapid test kits, as a reference method. Ultimately, the proposed biosensor based on the core-shell structure of gold NMIs and MIP opens interesting avenues in the detection of proteins with low cost, high sensitivity and significantstability for clinical applications.

Microstructure and Corrosion Characterization of a MgO/Hydroxyapatite Bilayer Coating by Plasma Electrolytic Oxidation Coupled with Flame Spraying on a Mg Alloy.

Thermally sprayed hydroxyapatite coatings are one of the main strategies to improve the bioactivation of metal implants. However, the naturally low corrosion resistance of these coatings is the main challenge for their use. In this study, plasma electrolytic oxidation (PEO) was used to create an intermediate layer. The anodization process was used for comparison. According to the polarization curves, the PEO layer was more effective than the anodized layer in reducing the corrosion current density (I corr of 0.05 × 10-9 A/cm2 vs I corr of 0.05 A/cm2). The results of electrochemical impedance spectroscopy showed higher resistance of the sample with a PEO interlayer than that of the sample with an anodized interlayer. The results of the hydrogen evolution test revealed that the PEO layer as a middle layer served as the main barrier for reducing the magnesium corrosion rate, especially during the initial immersion time.

Structural and Electrical Investigation of Cobalt-Doped NiOx/Perovskite Interface for Efficient Inverted Solar Cells.

Inorganic hole-transporting materials (HTMs) for stable and cheap inverted perovskite-based solar cells are highly desired. In this context, NiOx, with low synthesis temperature, has been employed. However, the low conductivity and the large number of defects limit the boost of the efficiency. An approach to improve the conductivity is metal doping. In this work, we have synthesized cobalt-doped NiOx nanoparticles containing 0.75, 1, 1.25, 2.5, and 5 mol% cobalt (Co) ions to be used for the inverted planar perovskite solar cells. The best efficiency of the devices utilizing the low temperature-deposited Co-doped NiOx HTM obtained a champion photoconversion efficiency of 16.42%, with 0.75 mol% of doping. Interestingly, we demonstrated that the improvement is not from an increase of the conductivity of the NiOx film, but due to the improvement of the perovskite layer morphology. We observe that the Co-doping raises the interfacial recombination of the device but more importantly improves the perovskite morphology, enlarging grain size and reducing the density of bulk defects and the bulk recombination. In the case of 0.75 mol% of doping, the beneficial effects do not just compensate for the deleterious one but increase performance further. Therefore, 0.75 mol% Co doping results in a significant improvement in the performance of NiOx-based inverted planar perovskite solar cells, and represents a good compromise to synthesize, and deposit, the inorganic material at low temperature, without losing the performance, due to the strong impact on the structural properties of the perovskite. This work highlights the importance of the interface from two different points of view, electrical and structural, recognizing the role of a low doping Co concentration, as a key to improve the inverted perovskite-based solar cells' performance.

A non-enzymatic sensor based on three-dimensional graphene foam decorated with Cu-xCu2O nanoparticles for electrochemical detection of glucose and its application in human serum.

In the present study, a porous structure consisting of three-dimensional graphene (3DG) decorated with Cu-based nanoparticles (NPs) (Cu or Cu-Cu2O) was synthesized in order to develop an enzyme-free electrochemical glucose sensor. Moreover, the effects of Cu-based nanoparticle concentrations on electrochemical properties and glucose detection were evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. Cu-based NPs@3DG showed markedly better electrochemical performance in glucose oxidation in alkaline solution compared to 3DG foam. Moreover, Cu-Cu2O NPs@3DG foam with the lowest concentration of Cu precursor showed excellent performance in glucose detection. A high sensitivity of 230.86 µA mM-1 cm-2 was obtained for this electrode in a linear range of 0.8-10 mM (R2 = 0.9951) and a detection limit of 16 µM. This sensor also showed good repeatability (relative standard deviation of 1.02%) and high selectivity (no observation of significant interference by interfering species such as ascorbic acid, dopamine, urea, and acetaminophen). The results confirmed that this electrode could be applied as a feasible and inexpensive non-enzymatic electrochemical glucose sensor.

Electroconductive Graphene-Containing Polymeric Patch: A Promising Platform for Future Cardiac Repair.

Myocardial infarction (MI) is one of the leading causes of death worldwide. The complications associated with MI can lead to the formation of nonconductive fibrous scar tissues. Despite the great improvement in electroconductive biomaterials to increase the physiological function of bio-engineered cardiac tissues in vivo, there are still several challenges in creating a suitable scaffold with appropriate mechanical and electrical properties. In the current study, a highly hydrophilic fibrous scaffold composed of polycaprolactone/chitosan/polypyrrole (PCP) and combined with functionalized graphene, to provide superior conductivity and a stronger mechanical cardiopatch, is presented. The PCP/graphene (PCPG) patches were optimized to show mechanical and conductive properties close to the native myocardium. Also, the engineered patches showed strong capability as a drug delivery system. Heparin, an anticoagulant drug, was loaded within the fibrous patches, and the adsorption of the bovine serum albumin (BSA) protein was evaluated. The optimized cardiopatch shows great potential to be used to provide mechanical support and restore electromechanical coupling at the site of MI to maintain a normal cardiac function.

A review on recent advancements in electrochemical biosensing using carbonaceous nanomaterials.

This review, with 201 references, describes the recent advancement in the application of carbonaceous nanomaterials as highly conductive platforms in electrochemical biosensing. The electrochemical biosensing is described in introduction by classifying biosensors into catalytic-based and affinity-based biosensors and statistically demonstrates the most recent published works in each category. The introduction is followed by sections on electrochemical biosensors configurations and common carbonaceous nanomaterials applied in electrochemical biosensing, including graphene and its derivatives, carbon nanotubes, mesoporous carbon, carbon nanofibers and carbon nanospheres. In the following sections, carbonaceous catalytic-based and affinity-based biosensors are discussed in detail. In the category of catalytic-based biosensors, a comparison between enzymatic biosensors and non-enzymatic electrochemical sensors is carried out. Regarding the affinity-based biosensors, scholarly articles related to biological elements such as antibodies, deoxyribonucleic acids (DNAs) and aptamers are discussed in separate sections. The last section discusses recent advancements in carbonaceous screen-printed electrodes as a growing field in electrochemical biosensing. Tables are presented that give an overview on the diversity of analytes, type of materials and the sensors performance. Ultimately, general considerations, challenges and future perspectives in this field of science are discussed. Recent findings suggest that interests towards 2D nanostructured electrodes based on graphene and its derivatives are still growing in the field of electrochemical biosensing. That is because of their exceptional electrical conductivity, active surface area and more convenient production methods compared to carbon nanotubes. Graphical abstract Schematic representation of carbonaceous nanomaterials used in electrochemical biosensing. The content is classified into non-enzymatic sensors and affinity/ catalytic biosensors. Recent publications are tabulated and compared, considering materials, target, limit of detection and linear range of detection.

Electrochemical molecularly bioimprinted siloxane biosensor on the basis of core/shell silver nanoparticles/EGFR exon 21 L858R point mutant gene/siloxane film for ultra-sensing of Gemcitabine as a lung cancer chemotherapy medication.

In search for improvements in bioanalysis electrochemical sensors, for better assessment of anti-cancer drugs, it is necessary for their detection limits to be minimized and the sensitivity and selectivity to be surpassed simultaneously; whereas, resolving any probable interfering with other medical treatments are considered. In this work, a novel approach was adopted for detection and assessment of Gemcitabine (GEM) as an anti-cancer drug based on evaluating its interaction with EGFR exon 21-point mutant gene. An electrochemical nanobiosensor was invented based on a new molecularly bioimprinted siloxane polymer (MBIS) strategy; in which the EGFR exon 21 acts as an identification probe. The roles of multi-walled carbon nanotubes and Ag nanoparticles (NPs) are to perform as a signal amplifier. The MBIS film was prepared by acid-catalysed hydrolysis/condensation of the sample solution, containing Ag NPs, ds-DNA of EGFR exon 21 point mutant gene, GEM as a template molecule, 3-(aminopropyl) trimethoxysilane (APTMS) and tetraethoxysilane. The interaction between the dsDNA and GEM was investigated by employing the modified biosensor and monitoring oxidation signal of guanine and adenine. The produced biosensor was characterized by XRD, FE-SEM, EDS, FT-IR and differential pulse voltammetry. The oxidation signals of adenine and guanine were in linear range when the device was subjected to various concentrations of GEM, from 1.5 to -93 µM, where a low detection limit 12.5 nmol L-1, and 48.8 nmol L-1 were recorded by guanine and adenine respectively. The developed biosensor did perform very well when employed for the actual samples; the stability was also approved which was acceptable for a reasonable time.

Synthesis and characterization of magnetite/Alyssum homolocarpum seed gum/Ag nanocomposite and determination of its antibacterial activity.

Due to applications of silver nanoparticles (Ag NPs) especially in advanced science fields, it is important to produce Ag antibacterial nanocomposites with enhanced antibacterial activity and reusability. Over the past decade researches about natural polymers have emphasized the use of them as nanoparticles coating. In this work, a novel core-shell antibacterial agent was synthesized through a three-step procedure. Fe3O4 nanoparticles (Fe3O4 NPs) were synthesized and coated with a natural polymer called Alyssum homolocarpum seed gum (AHSG). Ag NPs were immobilized on the AHSG resulting in formation of the new nanocomposite with improved antimicrobial properties. The immobilization of Ag NPs prevents the release of toxic Ag+ ions. The Fe3O4@AHSG@Ag nanocomposite could easily be separated from medium using an external magnetic field due to presence of the Fe3O4 superparamagnetic nanoparticles. The as-synthesized nanocomposite was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometer and dynamic light scattering. The results showed that the magnetic nanocomposite was synthesized and coated successfully. Finally, results of disk diffusion method demonstrated that the nanocomposite exhibits excellent antibacterial activity against gram-positive and gram-negative bacteria.

An injectable mechanically robust hydrogel of Kappa-carrageenan-dopamine functionalized graphene oxide for promoting cell growth.

An injectable nanohybrid hydrogel with robust mechanical properties was developed based on Methacrylate-Kappa-carrageenan (KaMA)-dopamine functionalized graphene oxide (GOPD) for soft tissue engineering. KaMA-GOPD hydrogels revealed shear-thinning behavior and injectability through interaction of active catechol groups of dopamine with other moieties in the structure of hydrogels. In addition, these interactions promoted mechanical properties of hydrogels, depending on the GOPD content. Noticeably, encapsulation of 20 wt.% GOPD significantly enhanced compressive strength (8-folds) and toughness (6-folds) of KaMA. Furthermore, the hybrid hydrogel consisting of 20 wt.% GOPD significantly reduced energy loss from 70% (at KaMA) to about 61%, after a two-cycle compression test, while significantly enhanced recovery of the KaMA structure. Reinforcing the KaMA with 20 wt.% GOPD resulted in enhanced fibroblast proliferation (2.5-times) and spreading (5.7 times) after 5 days of culture. Based on these findings, KaMA-GOPD hydrogel could be used for cell delivery through the injection process and applied as a suitable bio-ink for 3D-bioproiting process.

Peptide modified paper based impedimetric immunoassay with nanocomposite electrodes as a point-of-care testing of Alpha-fetoprotein in human serum.

Treatment for cancer depends on the type of cancer, and the stage or its development, and thus the need for point-of-care technology that can allow rapid and precise detection of biomarkers is increasing. Here, we present a simple on chip electrical detection of Alpha-fetoprotein (AFP). We rely on using a novel peptide modified plastic-paper microfluidic chips to perform efficient and specific impedimetric detection of AFP in human serum. The chips are prepared from a lower sheet of plastic and upper layer of cellulose chromatography paper modified with silver-20 wt% graphene printed electrodes. Diphenylalanine (FF) was proposed to involve in detection zone of the fabricated microchips in order to improve the sensing performance and the stability of immobilized antibodies according to amine-aldehyde reaction. The target protein is captured on the surface of microchips using specific monoclonal antibodies and the electrical response of the chip is monitored in the presence and absence of different concentrations of AFP. The influence of several parameters including the material types for screen printing of electrodes, FF concentrations, solvent and pH of FF solution on electrical response and cellulose fibers morphology was explored. The impedance measurements of AFP on the fabricated microchip in the optimized parameters exhibited a detection limit of 1 and 10 ng ml-1 in PBS and plasma, respectively. This platform developed here can be adopted to develop systems for rapid detection of biomarkers using portable electric devices.

Investigation and regulation of self-assembled well-ordered nano/microstructures via an aromatic α-amino acid.

In order to invent notable biomaterials, in this research d-phenylalanine as an aromatic α-amino acid has been studied for the synthesis of well-ordered self-assembled architectures such as wires, tubes and sheets under different synthesis conditions. Multiple factors are responsible for phenylalanine formation and herein the influence of several parameters including the substrate, concentration of the amino acid, solvent, pH, and heat treatment was explored. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Atomic Force Microscopy (AFM) were used to monitor the self-assembly process. It was observed that the collective action of different non-covalent interactions plays an important role in phenylalanine self-assembly into well-defined morphologies. In fact, when it was deposited onto different substrates or dissolved in the various solvents and exposed to a certain heat treatment, different supramolecular architectures, including 1D structures, branched structures, and nanosheet arrangements were observed.

Diagnosis of EGFR exon21 L858R point mutation as lung cancer biomarker by electrochemical DNA biosensor based on reduced graphene oxide /functionalized ordered mesoporous carbon/Ni-oxytetracycline metallopolymer nanoparticles modified pencil graphite electrode.

In this present work we made a novel, fast, selective and sensitive electrochemical genobiosensor to detection of EGFR exon 21 point mutation based on two step electropolymerization of Ni(II)-oxytetracycline conducting metallopolymer nanoparticles (Ni-OTC NPs) on the surface of pencil graphite electrode (PGE) which was modified by reduced graphene oxide/carboxyl functionalized ordered mesoporous carbon (rGO/f-OMC) nanocomposite. ssDNA capture probe with amine groups at the5' end which applied as recognition element was immobilized on the rGO/f-OMC/PGE surface via the strong amide bond. Ni-OTC metallopolymer NPs were electropolymerized to rGO/ssDNA-OMC/PGE surface and then hybridization fallows through the peak current change in differential pulse voltammetry (DPV) using Ni-OTC NPs as a redox label. The biosensor was characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), FT-IR spectroscopy, energy dispersive X-ray spectroscopy (EDX), cyclic voltammetry and Nitrogen adsorption-desorption analysis. The Ni-OTC current response verified only the complementary sequence indicating a significant reduction current signal in comparison to single point mismatched and non-complementary and sequences. Under optimal conditions, the prepared biosensor showed long-term stability (21 days) with a wide linear range from 0.1 µM to 3 µM with high sensitivity (0.0188 mA/µM) and low detection limit (120 nM).