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1.
Int J Artif Organs ; 47(8): 633-641, 2024 Aug.
Article in English | MEDLINE | ID: mdl-39113566

ABSTRACT

Cardiovascular diseases, particularly myocardial infarction, have significant healthcare challenges due to the limited regenerative capacity of injured heart tissue. Cardiac tissue engineering (CTE) offers a promising approach to repairing myocardial damage using biomaterials that mimic the heart's extracellular matrix. This study investigates the potential of graphene nanopowder (Gnp)-enhanced polycaprolactone (PCL) scaffolds fabricated via electrospinning to improve the properties necessary for effective cardiac repair. This work aimed to analyze scaffolds with varying graphene concentrations (0.5%, 1%, 1.5%, and 2% by weight) to determine their morphological, chemical, mechanical, and biocompatibility characteristics. The results presented that incorporating graphene improves PCL scaffolds' mechanical properties and cellular interactions. The optimal concentration of 1% graphene significantly enhanced mechanical properties and biocompatibility, promoting cell adhesion and proliferation. These findings suggest that Gnp-enhanced PCL scaffolds at this concentration can serve as a potent substrate for CTE providing insights into designing more effective biomaterials for myocardial restoration.


Subject(s)
Cell Proliferation , Graphite , Nanofibers , Polyesters , Tissue Engineering , Tissue Scaffolds , Tissue Engineering/methods , Graphite/chemistry , Polyesters/chemistry , Cell Proliferation/drug effects , Biocompatible Materials , Cell Adhesion/drug effects , Materials Testing , Animals , Myocytes, Cardiac/drug effects , Humans , Myocardium/pathology
2.
Bioelectrochemistry ; 160: 108795, 2024 Dec.
Article in English | MEDLINE | ID: mdl-39146929

ABSTRACT

E6 and E7 oncogenes are pivotal in the carcinogenic transformation in HPV infections and efficient diagnostic methods can ensure the detection and differentiation of HPV genotype. This study describes the development and validation of an electrochemical, label-free genosensor coupled with a microfluidic system for detecting the E6 and E7 oncogenes in cervical scraping samples. The nanostructuring employed was based on a cysteine and graphene quantum dots layer that provides functional groups, surface area, and interesting electrochemical properties. Biorecognition tests with cervical scraping samples showed differentiation in the voltammetric response. Low-risk HPV exhibited a lower biorecognition response, reflected in ΔI% values of 82.33 % ± 0.29 for HPV06 and 80.65 % ± 0.68 for HPV11 at a dilution of 1:100. Meanwhile, high-risk, HPV16 and HPV18, demonstrated ΔI% values of 96.65 % ± 1.27 and 93 % ± 0.026, respectively, at the same dilution. Therefore, the biorecognition intensity followed the order: HPV16 >HPV18 >HPV06 >HPV11. The limit of detection and the limit of quantification of E6E7 microfluidic LOC-Genosensor was 26 fM, and 79.6 fM. Consequently, the E6E7 biosensor is a valuable alternative for clinical HPV diagnosis, capable of detecting the potential for oncogenic progression even in the early stages of infection.


Subject(s)
Biosensing Techniques , Oncogene Proteins, Viral , Biosensing Techniques/methods , Humans , Oncogene Proteins, Viral/genetics , Female , Limit of Detection , Papillomavirus E7 Proteins/genetics , Cervix Uteri/virology , Graphite/chemistry , Papillomavirus Infections/diagnosis , Papillomavirus Infections/virology , Electrochemical Techniques/methods , Repressor Proteins/genetics , Microfluidic Analytical Techniques/methods , Microfluidic Analytical Techniques/instrumentation , Quantum Dots/chemistry , Lab-On-A-Chip Devices , Papillomaviridae/genetics , Papillomaviridae/isolation & purification
3.
Sensors (Basel) ; 24(15)2024 Aug 04.
Article in English | MEDLINE | ID: mdl-39124094

ABSTRACT

Graphene-based surface plasmon resonance (SPR) biosensors have emerged as a promising technology for the highly sensitive and accurate detection of biomolecules. This study presents a comprehensive theoretical analysis of graphene-based SPR biosensors, focusing on configurations with single and bimetallic metallic layers. In this study, we investigated the impact of various metallic substrates, including gold and silver, and the number of graphene layers on key performance metrics: sensitivity of detection, detection accuracy, and quality factor. Our findings reveal that configurations with graphene first supported on gold exhibit superior performance, with sensitivity of detection enhancements up to 30% for ten graphene layers. In contrast, silver-supported configurations, while demonstrating high sensitivity, face challenges in maintaining detection accuracy. Additionally, reducing the thickness of metallic layers by 30% optimizes light coupling and enhances sensor performance. These insights highlight the significant potential of graphene-based SPR biosensors in achieving high sensitivity of detection and reliability, paving the way for their application in diverse biosensing technologies. Our findings pretend to motivate future research focusing on optimizing metallic layer thickness, improving the stability of silver-supported configurations, and experimentally validating the theoretical findings to further advance the development of high-performance SPR biosensors.


Subject(s)
Biosensing Techniques , Gold , Graphite , Silver , Surface Plasmon Resonance , Graphite/chemistry , Surface Plasmon Resonance/methods , Silver/chemistry , Biosensing Techniques/methods , Biosensing Techniques/instrumentation , Gold/chemistry
4.
Materials (Basel) ; 17(15)2024 Aug 01.
Article in English | MEDLINE | ID: mdl-39124446

ABSTRACT

In this work, iron hexacyanoferrate (FeHCF-Prussian blue) particles have been grown onto a reduced graphene oxide substrate through a pulsed electrodeposition process. Thus, the prepared FeHCF electrode exhibits a specific volumetric capacitance of 88 F cm-3 (specific areal capacitance of 26.6 mF cm-2) and high cycling stability with a capacitance retention of 93.7% over 10,000 galvanostatic charge-discharge cycles in a 1 M KCl electrolyte. Furthermore, two identical FeHCF electrodes were paired up in order to construct a symmetrical supercapacitor, which delivers a wide potential window of 2 V in a 1 M KCl electrolyte and demonstrates a large energy density of 27.5 mWh cm-3 at a high power density of 330 W cm-3.

5.
Molecules ; 29(15)2024 Aug 02.
Article in English | MEDLINE | ID: mdl-39125063

ABSTRACT

The advancement of traditional sample preparation techniques has brought about miniaturization systems designed to scale down conventional methods and advocate for environmentally friendly analytical approaches. Although often referred to as green analytical strategies, the effectiveness of these methods is intricately linked to the properties of the sorbent utilized. Moreover, to fully embrace implementing these methods, it is crucial to innovate and develop new sorbent or solid phases that enhance the adaptability of miniaturized techniques across various matrices and analytes. Graphene-based materials exhibit remarkable versatility and modification potential, making them ideal sorbents for miniaturized strategies due to their high surface area and functional groups. Their notable adsorption capability and alignment with green synthesis approaches, such as bio-based graphene materials, enable the use of less sorbent and the creation of biodegradable materials, enhancing their eco-friendly aspects towards green analytical practices. Therefore, this study provides an overview of different types of hybrid graphene-based materials as well as their applications in crucial miniaturized techniques, focusing on offline methodologies such as stir bar sorptive extraction (SBSE), microextraction by packed sorbent (MEPS), pipette-tip solid-phase extraction (PT-SPE), disposable pipette extraction (DPX), dispersive micro-solid-phase extraction (d-µ-SPE), and magnetic solid-phase extraction (MSPE).

6.
ACS Appl Bio Mater ; 7(8): 5530-5540, 2024 Aug 19.
Article in English | MEDLINE | ID: mdl-39093994

ABSTRACT

This study reports on the modification of bacterial cellulose (BC) membranes produced by static fermentation of Komagataeibacter xylinus bacterial strains with graphene oxide-silver nanoparticles (GO-Ag) to yield skin wound dressings with improved antibacterial properties. The GO-Ag sheets were synthesized through chemical reduction with sodium citrate and were utilized to functionalize the BC membranes (BC/GO-Ag). The BC/GO-Ag composites were characterized to determine their surface charge, morphology, exudate absorption, antimicrobial activity, and cytotoxicity by using fibroblast cells. The antimicrobial activity of the wound dressings was assessed against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The results indicate that the BC/GO-Ag dressings can inhibit ∼70% of E. coli cells. Our findings also revealed that the porous BC/GO-Ag antimicrobial dressings can efficiently retain 94% of exudate absorption after exposure to simulated body fluid (SBF) for 24 h. These results suggest that the dressings could absorb excess exudate from the wound during clinical application, maintaining adequate moisture, and promoting the proliferation of epithelial cells. The BC/GO-Ag hybrid materials exhibited excellent mechanical flexibility and low cytotoxicity to fibroblast cells, making excellent wound dressings able to control bacterial infectious processes and promote the fast healing of dermal lesions.


Subject(s)
Anti-Bacterial Agents , Biocompatible Materials , Cellulose , Escherichia coli , Graphite , Materials Testing , Metal Nanoparticles , Microbial Sensitivity Tests , Silver , Staphylococcus aureus , Wound Healing , Graphite/chemistry , Graphite/pharmacology , Silver/chemistry , Silver/pharmacology , Wound Healing/drug effects , Cellulose/chemistry , Cellulose/pharmacology , Metal Nanoparticles/chemistry , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Staphylococcus aureus/drug effects , Escherichia coli/drug effects , Biocompatible Materials/chemistry , Biocompatible Materials/pharmacology , Particle Size , Pseudomonas aeruginosa/drug effects , Gluconacetobacter xylinus/chemistry , Humans , Mice , Bandages , Animals
7.
Molecules ; 29(14)2024 Jul 10.
Article in English | MEDLINE | ID: mdl-39064841

ABSTRACT

Bone tissue engineering is a promising alternative to repair wounds caused by cellular or physical accidents that humans face daily. In this sense, the search for new graphene oxide (GO) nanofillers related to their degree of oxidation is born as an alternative bioactive component in forming new scaffolds. In the present study, three different GOs were synthesized with varying degrees of oxidation and studied chemically and tissue-wise. The oxidation degree was determined through infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron (XPS), and Raman spectroscopy (RS). The morphology of the samples was analyzed using scanning electron microscopy (SEM). The oxygen content was deeply described using the deconvolution of RS and XPS techniques. The latter represents the oxidation degree for each of the samples and the formation of new bonds promoted by the graphitization of the material. In the RS, two characteristic bands were observed according to the degree of oxidation and the degree of graphitization of the material represented in bands D and G with different relative intensities, suggesting that the samples have different crystallite sizes. This size was described using the Tuinstra-Koenig model, ranging between 18.7 and 25.1 nm. Finally, the bone neoformation observed in the cranial defects of critical size indicates that the F1 and F2 samples, besides being compatible and resorbable, acted as a bridge for bone healing through regeneration. This promoted healing by restoring bone and tissue structure without triggering a strong immune response.


Subject(s)
Bone Regeneration , Graphite , Tissue Engineering , Tissue Scaffolds , Graphite/chemistry , Bone Regeneration/drug effects , Tissue Engineering/methods , Animals , Tissue Scaffolds/chemistry , Nanostructures/chemistry , Bone and Bones/drug effects , Spectrum Analysis, Raman , Oxidation-Reduction , X-Ray Diffraction , Biocompatible Materials/chemistry , Biocompatible Materials/pharmacology , Rats , Spectroscopy, Fourier Transform Infrared
8.
Polymers (Basel) ; 16(14)2024 Jul 21.
Article in English | MEDLINE | ID: mdl-39065398

ABSTRACT

Graphene is a promising biomaterial. However, its dispersion in aqueous medium is challenging. This study aimed to modify graphene nanoparticles with L-dopa to improve the properties of experimental dental adhesives. Adhesives were formulated with 0% (control), 0.25%, 0.5%, and 0.75% of graphene, modified or not. Particle modification and dispersion were microscopically assessed. Degree of conversion was tested by Fourier-transform infrared spectroscopy. Flexural strength and modulus of elasticity were evaluated by a 3-point flexural test. Bond strength was tested by shear. To test water sorption/solubility, samples were weighed during hydration and dehydration. Antibacterial activity was tested by Streptococcus mutans colony-forming units quantification. Cytotoxicity on fibroblasts was evaluated through a dentin barrier test. The modification of graphene improved the particle dispersion. Control presented the highest degree of conversion, flexural strength, and bond strength. In degree of conversion, 0.25% of groups were similar to control. In bond strength, groups of graphene modified by L-dopa were similar to Control. The modulus of elasticity was similar between groups. Cytotoxicity and water sorption/solubility decreased as particles increased. Compared to graphene, less graphene modified by L-dopa was needed to promote antibacterial activity. By modifying graphene with L-dopa, the properties of graphene and, therefore, the adhesives incorporated by it were enhanced.

9.
Pharmaceutics ; 16(7)2024 Jun 25.
Article in English | MEDLINE | ID: mdl-39065553

ABSTRACT

Core-shell micro/nanomotors have garnered significant interest in biomedicine owing to their versatile task-performing capabilities. However, their effectiveness for photothermal therapy (PTT) still faces challenges because of their poor tumor accumulation, lower light-to-heat conversion, and due to the limited penetration of near-infrared (NIR) light. In this study, we present a novel core-shell micromotor that combines magnetic and photothermal properties. It is synthesized via the template-assisted electrodeposition of iron (Fe) and reduced graphene oxide (rGO) on a microtubular pore-shaped membrane. The resulting Fe-rGO micromotor consists of a core of oval-shaped zero-valent iron nanoparticles with large magnetization. At the same time, the outer layer has a uniform reduced graphene oxide (rGO) topography. Combined, these Fe-rGO core-shell micromotors respond to magnetic forces and near-infrared (NIR) light (1064 nm), achieving a remarkable photothermal conversion efficiency of 78% at a concentration of 434 µg mL-1. They can also carry doxorubicin (DOX) and rapidly release it upon NIR irradiation. Additionally, preliminary results regarding the biocompatibility of these micromotors through in vitro tests on a 3D breast cancer model demonstrate low cytotoxicity and strong accumulation. These promising results suggest that such Fe-rGO core-shell micromotors could hold great potential for combined photothermal therapy.

10.
Sensors (Basel) ; 24(14)2024 Jul 18.
Article in English | MEDLINE | ID: mdl-39066066

ABSTRACT

This work explores the transformative role of graphene in enhancing the performance of surface plasmon resonance (SPR)-based biosensors. The motivation for this review stems from the growing interest in the unique properties of graphene, such as high surface area, excellent electrical conductivity, and versatile functionalization capabilities, which offer significant potential to improve the sensitivity, specificity, and stability of SPR biosensors. This review systematically analyzes studies published between 2010 and 2023, covering key metrics of biosensor performance. The findings reveal that the integration of graphene consistently enhances sensitivity. Specificity, although less frequently reported numerically, showed promising results, with high specificity achieved at sub-nanomolar concentrations. Stability enhancements are also significant, attributed to the protective properties of graphene and improved biomolecule adsorption. Future research should focus on mechanistic insights, optimization of integration techniques, practical application testing, scalable fabrication methods, and comprehensive comparative studies. Our findings provide a foundation for future research, aiming to further optimize and harness the unique physical properties of graphene to meet the demands of sensitive, specific, stable, and rapid biosensing in various practical applications.


Subject(s)
Biosensing Techniques , Graphite , Surface Plasmon Resonance , Surface Plasmon Resonance/methods , Graphite/chemistry , Biosensing Techniques/methods , Humans
11.
Odontology ; 2024 Jul 24.
Article in English | MEDLINE | ID: mdl-39046588

ABSTRACT

To evaluate the microstructural characterization, mechanical properties and antimicrobial activity of acrylic resins incorporated with different concentrations of reduced graphene oxide (rGO). Specimens were made of self-cured and heat-cured acrylic resins for the control group and concentrations of 0.5%, 1%, and 3%. The microstructural characterization was evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDS). For mechanical testing, flexural strength, and Knoop hardness tests were performed. Microbiological evaluations were performed by colony forming units (CFU) analysis, tetrazolium salt reduction (XTT), and SEM images. The modified acrylic resins showed increased mechanical properties at low concentrations (p < 0.05) and with reduced S. mutans (p < 0.05). Reduced graphene oxide interfered with the mechanical performance and microbiological properties of acrylic resins depending on the concentration of rGO, and type of polymerization and microorganism evaluated. The incorporation of graphene compounds into acrylic resins is an alternative to improve the antimicrobial efficacy and performance of the material.

12.
Chemosphere ; 362: 142730, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38950742

ABSTRACT

Photocatalytic membranes are a promising technology for water and wastewater treatment. Towards circular economy, extending the lifetime of reverse osmosis (RO) membranes for as long as possible is extremely important, due to the great amount of RO modules discarded every year around the world. Therefore, in the present study, photocatalytic membranes made of recycled post-lifespan RO membrane (polyamide thin-film composite), TiO2 nanoparticles and graphene oxide are used in the treatment tertiary-treated domestic wastewater to remove trace organic compounds (TrOCs). The inclusion of dopamine throughout the surface modification process enhanced the stability of the membranes to be used as long as 10 months of operation. We investigated TrOCs removal by the membrane itself and in combination with UV-C and visible light by LED. The best results were obtained with integrated membrane UV-C system at pH 9, with considerable reductions of diclofenac (92%) and antipyrine (87%). Changes in effluent pH demonstrated an improvement in the attenuation of TrOCs concentration at higher pHs. By modifying membranes with nanocomposites, an increase in membrane hydrophilicity (4° contact angle reduction) was demonstrated. The effect of the lamp position on the light fluence that reaches the membrane was assessed, and greater values were found in the middle of the membrane, providing parameters for process optimization (0.29 ± 0.10 mW cm-2 at the center of the membrane and 0.07 ± 0.03 mW cm-2 at the right and left extremities). Photocatalytic recycled TiO2-GO membranes have shown great performance to remove TrOCs and extend membrane lifespan, as sustainable technology to treat wastewater.


Subject(s)
Graphite , Membranes, Artificial , Titanium , Waste Disposal, Fluid , Wastewater , Water Pollutants, Chemical , Water Purification , Titanium/chemistry , Water Pollutants, Chemical/chemistry , Wastewater/chemistry , Graphite/chemistry , Waste Disposal, Fluid/methods , Catalysis , Water Purification/methods , Organic Chemicals/chemistry , Recycling/methods , Ultraviolet Rays , Osmosis
13.
Nanotechnology ; 35(42)2024 Aug 02.
Article in English | MEDLINE | ID: mdl-39059417

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), etiological agent for the coronavirus disease 2019 (COVID-19), has resulted in over 775 million global infections. Early diagnosis remains pivotal for effective epidemiological surveillance despite the availability of vaccines. Antigen-based assays are advantageous for early COVID-19 detection due to their simplicity, cost-effectiveness, and suitability for point-of-care testing (PoCT). This study introduces a graphene field-effect transistor-based biosensor designed for high sensitivity and rapid response to the SARS-CoV-2 spike protein. By functionalizing graphene with monoclonal antibodies and applying short-duration gate voltage pulses, we achieve selective detection of the viral spike protein in human serum within 100 µs and at concentrations as low as 1 fg ml-1, equivalent to 8 antigen molecules perµl of blood. Furthermore, the biosensor estimates spike protein concentrations in serum from COVID-19 patients. Our platform demonstrates potential for next-generation PoCT antigen assays, promising fast and sensitive diagnostics for COVID-19 and other infectious diseases.


Subject(s)
Biosensing Techniques , COVID-19 , Graphite , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Transistors, Electronic , Spike Glycoprotein, Coronavirus/analysis , Spike Glycoprotein, Coronavirus/immunology , Biosensing Techniques/instrumentation , Biosensing Techniques/methods , Graphite/chemistry , Humans , SARS-CoV-2/isolation & purification , SARS-CoV-2/immunology , COVID-19/diagnosis , COVID-19/blood , COVID-19/virology , Sensitivity and Specificity , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/chemistry
14.
Mikrochim Acta ; 191(8): 492, 2024 07 27.
Article in English | MEDLINE | ID: mdl-39066907

ABSTRACT

The development and application of an electrochemical sensor is reported for detection of poly(3-hydroxybutyrate) (P3HB) - a bioplastic derived from agro-industrial residues. To overcome the challenges of molecular imprinting of macromolecules such as P3HB, this study employed methanolysis reaction to break down the P3HB biopolymer chains into methyl 3-hydroxybutyrate (M3HB) monomers. Thereafter, M3HB were employed as the target molecules in the construction of molecularly imprinted sensors. The electrochemical device was then prepared by electropolymerizing a molecularly imprinted poly (indole-3-acetic acid) thin film on a glassy carbon electrode surface modified with reduced graphene oxide (GCE/rGO-MIP) in the presence of M3HB. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), scanning electron microscopy with field emission gun (SEM-FEG), Raman spectroscopy, attenuated total reflection Fourier-transform infrared (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the electrode surface. Under ideal conditions, the MIP sensor exhibited a wide linear working range of 0.1 - 10 nM and a detection limit of 0.3 pM (n = 3). The sensor showed good repeatability, selectivity, and stability over time. For the sensor application, the bioproduction of P3HB was carried out in a bioreactor containing the Burkholderia glumae MA13 strain and sugarcane byproducts as a supplementary carbon source. The analyses were validated through recovery assays, yielding recovery values between 102 and 104%. These results indicate that this MIP sensor can present advantages in the monitoring of P3HB during the bioconversion process.


Subject(s)
Burkholderia , Electrochemical Techniques , Electrodes , Graphite , Hydroxybutyrates , Molecularly Imprinted Polymers , Polyesters , Graphite/chemistry , Polyesters/chemistry , Hydroxybutyrates/chemistry , Burkholderia/chemistry , Burkholderia/metabolism , Electrochemical Techniques/methods , Electrochemical Techniques/instrumentation , Molecularly Imprinted Polymers/chemistry , Limit of Detection , Oxidation-Reduction , Polyhydroxybutyrates
15.
Materials (Basel) ; 17(13)2024 Jul 02.
Article in English | MEDLINE | ID: mdl-38998324

ABSTRACT

In this communication, the design and fabrication of optical active metamaterials were developed by the incorporation of graphene and joining it to different substrates with variable spectroscopical properties. It focuses on how graphene and its derivatives could generate varied optical setups and materials considering modified and enhanced optics within substrates and surfaces. In this manner, it is discussed how light could be tuned and modified along its path from confined nano-patterned surfaces or through a modified micro-lens. In addition to these optical properties generated from the physical interaction of light, it should be added that the non-classical light pathways and quantum phenomena could participate. In this way, graphene and related carbon-based materials with particular properties, such as highly condensed electronics, pseudo-electromagnetic properties, and quantum and luminescent properties, could be incorporated. Therefore, the modified substrates could be switched by photo-stimulation with variable responses depending on the nature of the material constitution. Therefore, the optical properties of graphene and its derivatives are discussed in these types of metasurfaces with targeted optical active properties, such as within the UV, IR, and terahertz wavelength intervals, along with their further properties and respective potential applications.

16.
Environ Sci Pollut Res Int ; 31(31): 44374-44384, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38949732

ABSTRACT

The presence of phenazopyridine in water is an environmental problem that can cause damage to human health and the environment. However, few studies have reported the adsorption of this emerging contaminant from aqueous matrices. Furthermore, existing research explored only conventional modeling to describe the adsorption phenomenon without understanding the behavior at the molecular level. Herein, the statistical physical modeling of phenazopyridine adsorption into graphene oxide is reported. Steric, energetic, and thermodynamic interpretations were used to describe the phenomenon that controls drug adsorption. The equilibrium data were fitted by mono, double, and multi-layer models, considering factors such as the numbers of phenazopyridine molecules by adsorption sites, density of receptor sites, and half saturation concentration. Furthermore, the statistical physical approach also calculated the thermodynamic parameters (free enthalpy, internal energy, Gibbs free energy, and entropy). The maximum adsorption capacity at the equilibrium was reached at 298 K (510.94 mg g-1). The results showed the physical meaning of adsorption, indicating that the adsorption occurs in multiple layers. The temperature affected the density of receptor sites and half saturation concentration. At the same time, the adsorbed species assumes different positions on the adsorbent surface as a function of the increase in the temperature. Meanwhile, the thermodynamic functions revealed increased entropy with the temperature and the equilibrium concentration.


Subject(s)
Nanostructures , Thermodynamics , Adsorption , Nanostructures/chemistry , Analgesics/chemistry , Graphite/chemistry , Water Pollutants, Chemical/chemistry , Carbon/chemistry
17.
Polymers (Basel) ; 16(13)2024 Jun 27.
Article in English | MEDLINE | ID: mdl-39000683

ABSTRACT

Chitosan is a biopolymer with unique properties that have attracted considerable attention in various scientific fields in recent decades. Although chitosan is known for its poor electrical and mechanical properties, there is interest in producing chitosan-based materials reinforced with carbon-based materials to impart exceptional properties such as high electrical conductivity and high Young's modulus. This study describes the synergistic effect of carbon-based materials, such as reduced graphene oxide and carbon nanotubes, in improving the electrical, optical, and mechanical properties of chitosan-based films. Our findings demonstrate that the incorporation of reduced graphene oxide influences the crystallinity of chitosan, which considerably impacts the mechanical properties of the films. However, the incorporation of a reduced graphene oxide-carbon nanotube complex not only significantly improves the mechanical properties but also significantly improves the optical and electrical properties, as was demonstrated from the photoluminescence studies and resistivity measurements employing the four-probe technique. This is a promising prospect for the synthesis of new materials, such as biopolymer films, with potential applications in optical, electrical, and biomedical bioengineering applications.

18.
Proc Inst Mech Eng H ; 238(7): 793-802, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38902971

ABSTRACT

The objective of this study was to synthesize and characterize porous Cellulose Acetate (CA) scaffolds using the electrospinning technique and functionalize the surface of the scaffolds obtained through the dip-coating method with a Hydroxyapatite (HA) nanocomposite and varying concentrations of graphene oxide (GO) for application in tissue engineering regeneration techniques. The scaffolds were divided into four distinct groups based on their composition: 1) CA scaffolds; 2) CAHAC scaffolds; 3) CAHAGOC 1.0% scaffolds; 4) CAHAGOC 1.5% scaffolds. Scaffold analyses were conducted using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS), and in vitro cell viability assays (WST). For the biological test analysis, Variance (two-way) was used, followed by Tukey's post-test (α = 0.05). The XRD results revealed the predominant presence of CaP phases in the CAHAC, CAHAGOC 1.0%, and CAHAGOC 1.5% groups, emphasizing the presence of HA in the scaffolds. FTIR demonstrated characteristics of cellulose and PO4 bands in the groups containing HA, confirming the presence of CaP in the synthesized materials, as also indicated by XRD. Raman spectroscopy showed the presence of D and G bands, consistent with GO, confirming the successful incorporation of the HAGO nanocomposite into the scaffolds. The micrographs displayed overlapping electrospun fibers, forming the three-dimensional structure in the produced scaffolds. It was possible to observe hydroxyapatite crystals filling some of these pores, creating a suitable structure for cell adhesion, proliferation, and nutrition, as corroborated by the results of in vitro tests. All scaffolds exhibited high cell viability, with significant cell proliferation. Even after 48 h, there was a slight reduction in the number of cells, but a noteworthy increase in cell proliferation was evident in the CAHAGOC 1.5% group after 48 h (p < 0.05). In conclusion, it can be affirmed that the produced scaffolds demonstrated physical and biological characteristics and properties capable of promoting cell adhesion and proliferation. Therefore, they represent significant potential for application in tissue engineering, offering a new perspective regarding techniques and biomaterials applied in regenerative therapies.


Subject(s)
Cellulose , Durapatite , Graphite , Nanocomposites , Tissue Engineering , Tissue Scaffolds , Graphite/chemistry , Durapatite/chemistry , Cellulose/chemistry , Cellulose/analogs & derivatives , Nanocomposites/chemistry , Tissue Scaffolds/chemistry , Cell Survival/drug effects , Animals
19.
Bioresour Technol ; 406: 130961, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38876281

ABSTRACT

This study investigates the potential of humic substances (HS) and graphene oxide (GO), as extracellular electron acceptors (EEA) for nitrification, aiming to explore alternatives to sustain this process in wastewater treatment systems. Experimental results demonstrate the conversion of ammonium to nitrate (up to 87 % of conversion) coupled to the reduction of either HS or GO by anaerobic consortia. Electron balance confirmed the contribution of HS and GO to ammonium oxidation. Tracer analysis in incubations performed with 15NH4+ demonstrated 15NO3- as the main product with a minor fraction ending as 29N2. Phylogenetic analysis identified Firmicutes, Euryarchaeota, and Chloroflexi as the microbial lineages potentially involved in anoxic nitrification linked to HS reduction. This study introduces a new avenue for research in which carbon-based materials with electron-accepting capacity may support the anoxic oxidation of ammonium, for instance in bioelectrochemical systems in which carbon-based anodes could support this novel process.


Subject(s)
Carbon , Nitrification , Carbon/chemistry , Electrons , Graphite/chemistry , Phylogeny , Oxidation-Reduction , Ammonium Compounds/metabolism , Anaerobiosis , Nitrates/metabolism , Bacteria/metabolism
20.
Polymers (Basel) ; 16(12)2024 Jun 13.
Article in English | MEDLINE | ID: mdl-38932027

ABSTRACT

In this work, the electrochemical synthesis of PANI and GO-modified PANI was performed using cyclic voltammetry, varying the amount of GO, 1 mg (PG1), 5 mg (PG5), and 10 mg (PG10) to analyze the effect of the amount of GO on the composite. PANI, PG1, PG5, and PG10 materials were characterized using optical microscopy, SEM, UV-vis, FTIR, Raman, and wettability. A stability test was also carried out by putting the materials to 500 oxidation-reduction cycles using cyclic voltammetry. The synthesis method allowed GO in PANI to be added through a chemical interaction between the two compounds. It was also found that the addition of GO led to an improvement in the hydrophilic character of the composite, which would lead to an improvement in the diffusion of reagents/species when the composites are used in aqueous media processes. The results of the stability test showed that the PG10 material presented a lower % loss of specific capacitance and energy compared with the other materials, which indicates that the GO presence (in the amount specified) improves the stability of the PANI. The PG10 material showed favorable and promising conditions for its use in fuel cell and battery processes.

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