L-arginine modified graphene oxide: A novel heterogeneous catalyst for synthesis of benzo[b]pyrans and pyrano[3,2‑c]chromenes

Curcumin@ graphene oxide/chitosan/arginine hydrogel: A novel approach to treat Candida periprosthetic joint infections

Candida albicans, responsible for nearly 70% of fungal infections, is a leading cause of life-threatening invasive infections, particularly in healthcare settings, with a mortality rate approaching 40% even after medical treatment. This study introduces a novel antifungal agent such as Curcumin@Graphene Oxide/Chitosan/Arginine nanocomposite hydrogel (Cur@GO/CS/Arg), targeting Candida albicans, a primary cause of periprosthetic joint infections (PJIs). The hydrogel exhibited remarkable antifungal efficacy, characterized by a 17 mm inhibition zone, a minimum inhibitory concentration (MIC) of 1.25 mg/ml, and a minimum fungicidal concentration (MFC) of 2.5 mg/ml, confirming its fungicidal properties based on the tolerance ratio. Additionally, it significantly reduced biofilm formation, highlighting its potent antifungal action. Furthermore, it demonstrated excellent biosafety, as evidenced by a minimal hemolytic effect at 50 μg/ml. These findings underscore the synergistic interactions among curcumin, graphene oxide, chitosan, and arginine, which enhance antifungal activity. This study offers a promising strategy for managing Candida albicans-associated PJIs, enabling safer and more effective treatment.

Dual acid-base catalysis with biologically modified graphene oxide: a sustainable route to polyhydroquinolines with antimicrobial properties

This article conducts an in-depth examination of graphene oxide-aspartic acid (GO-As) as a novel bifunctional nano-organocatalyst distinguished by both catalytic and antibacterial properties. The research elucidates the synthesis of GO through Hummer's method, followed by the covalent attachment of aspartic acid to the surface of GO nanosheets. This innovative approach is particularly notable as it circumvents the use of hazardous chemicals, thereby promoting environmental sustainability. The newly developed catalyst underwent rigorous analysis employing a variety of spectroscopic techniques, including Fourier Transform Infrared (FT-IR) spectroscopy, Energy-Dispersive X-ray Spectroscopy (EDX), mapping, Field Emission Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy. The findings indicate that the catalyst effectively synthesizes polyhydroquinoline derivatives while demonstrating significant stability over multiple reuse cycles, underscoring its potential applicability in organic synthesis. Furthermore, the antibacterial properties of the GO-modified aspartic acid were evaluated against six pathogenic bacterial species. The results reveal substantial antibacterial activity against both Gram-positive and Gram-negative strains, including two antibiotic-resistant bacteria: Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), thermogravimetric analysis (TGA), and Raman. In conclusion, the investigation of GO-As as a bifunctional heterogeneous nano-organocatalyst represents a promising advancement in the development of environmentally friendly and effective catalysts with noteworthy antibacterial characteristics.

L-Aspartic acid-functionalized magnetic nanoparticles: as a new magnetically reusable bifunctional acid-base catalysts for the synthesis of benzo[b]pyran and pyrano[3,2-c] chromene derivatives

"Green chemistry" describes the development of new technologies that reduce or eliminate the need for hazardous compounds or the production of them. In order to accomplish this goal, we have developed a new magnetic recyclable biocatalyst in this study by successfully applying aspartic acid to magnetic nanoparticles. Aspartic acid's molecular makeup made it possible for it to stabilize on magnetic nanoparticles using a straightforward method. We characterized the synthesized catalyst using microscopic and spectroscopic techniques such as Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM). The catalytic activity of this organocatalyst was evaluated for the synthesis of benzo[b]pyran and pyrano[3,2-c] chromene derivatives, exhibiting excellent efficiency. This protocol offers several benefits, such as using a low-cost biocatalyst, nontoxicity, high product yield, easy separation, short reaction times, catalyst reusability, and H2O/EtOH solvent. In summary, our research indicates a feasible approach towards developing a novel magnetic biocatalyst suitable for application in organic synthesis.

A novel heterogeneous biocatalyst based on graphene oxide for synthesis of pyran derivatives

Graphene oxide modified with tryptophan (GO-Trp) has been introduced as a new heterogeneous acid-base biocatalyst for synthesis of some pyran derivatives. GO was prepared according to the Hummer's method and tryptophan as a low-cost green amino acid is covalently bonded to the surface of GO without any organic or toxic reagents in a green way. The new catalyst was characterized by different spectroscopic methods such as Fourier transform infrared, X-ray diffraction (XRD), etc. …. The results of XRD patterns showed an increase in the distance between the GO plates in the presence of the modifying agent which specifies the presence of amino acid between the GO layers. XPS analysis also confirmed successful modification through the presence of C-N bonds in the structure of the catalyst. In addition, improvements in thermal stability and changes in the morphology of the samples were observed using thermogravimetric analysis and Field emission scanning electron microscopy analysis respectively. Evaluation of the catalyst performance in the synthesis of some benzo[b]pyran and pyrano[3,2-c] chromene derivatives showed presentable results. Seven benzo[b]pyran (4a-4g) and five pyrano[3,2-c] chromene (4h-4l) derivatives were synthesized. GO-Trp as a safe, natural and efficient catalyst, could be reused up to 5 runs for synthesis of pyran derivatives without any significant decrease in its potency. High purity of the products and desirable yields are other points that make the present work more attractive.

Graphene Oxide-Arginine Composites: Efficient Dual Function Materials for Integrated CO2 Capture and Conversion

The "on-demand" capture and utilization of CO2 is effectively realized with a readily accessible dual function organic composite. The covalent and controlled derivatization of graphene oxide (GO) surface with naturally occurring arginine led to a "smart" material capable of capturing (chemisorption) CO2 from high-purity flue-gas as well as low-concentration streams (i. e. direct air capture) and concomitant chemical activation toward the incorporation into cyclic carbonates. The overall integrated CO2 capture and conversion (ICCC) strategy has been fully elucidated mechanistically via dedicated computational, spectroscopic and thermal analyses.

Glucose microenvironment sensitive degradation of arginine modified calcium sulfate reinforced poly(lactide-co-glycolide) composite scaffolds

Poly(lactide-co-glycolide) (PLGA) and calcium sulfate composites are promising biodegradable biomaterials but are still challenging to use in people with high levels of blood glucose or diabetes. To date, the influence of glucose on their degradation has not yet been elucidated and thus calls for more research attention. Herein, a novel calcium sulfate whisker with L-arginine was used to effectively tune its crystal morphology and was employed as a reinforced phase to construct the PLGA-based composite scaffolds (ArgCSH/PLGA) with a sleeve porous structure. ArgCSH/PLGA showed excellent elastic modulus and strength in the compression and bending models. Moreover, an in vitro immersion test showed that ArgCSH/PLGA possessed degradation and redeposition behaviors sensitive to glucose concentration, and the adsorbed Arg played a crucial role in the degradation process. The subsequent cell functional evaluation showed that ArgCSH could effectively protect cells from damage caused by AGEs and promote osteogenic differentiation. The corresponding degradation products of ArgCSH/PLGA displayed the ability to regulate osteoblast bone differentiation and accelerate matrix mineralization. These findings provide new insights into the interaction between biomaterials and the physiological environment, which may be useful in expanding the targeted choice of efficient bone graft biodegradable materials for diabetic osteoporosis.

Graphene oxide immobilized 2-morpholinoethanamine as a versatile acid-base catalyst for synthesis of some heterocyclic compounds and molecular docking study

In this study, a new heterogeneous catalyst was synthesized based on graphene oxide (GO) as a natural material. On the surface of nanosheet graphene oxide, 2-Morpholinoethanamine was immobilized using a non-toxic, green, and simple method. This resulted in the preparation of a bifunctional acid-base nanocatalyst. The synthesized composite was fully characterized using various methods, including Fourier transform infrared spectrometry (FT-IR), scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), mapping, Raman spectroscopy, X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and CHN elemental analysis. The catalytic reactivity of GO-mor was investigated in the one-pot synthesis of some benzo[b]pyran, pyrano[3,2-c]chromene, and polyhydroquinoline derivatives, yielding good efficiency and short reaction times. In addition, several recent studies have shown that some derivatives of pyran, chromene, and quinoline have remarkable anti COVID activity. Particularly, COVID-19 3CLpro/Mpro is considered a potential target for the treatment of this virus. For this purpose, docking models were constructed using the corresponding crystal structures with the synthesized derivatives. Based on the docking score and similarity of the binding mode to remdesivir and elvitegravir (the only approved drugs for the treatment of COVID-19), A2, B1, and C4 were selected as promising candidates for further research.

A novel heterogeneous acid-base nano-catalyst designed based on graphene oxide for synthesis of spiro-indoline-pyranochromene derivatives

Nano graphene oxide/3-aminopyridine has been introduced as a new, efficient and robust heterogeneous organic catalyst for synthesis of spiro-indoline-pyranochromene derivatives. Nano graphene oxide/3-aminopyridine was provided in an easy and green way from GO. Firstly, graphene oxide (GO) was synthesized and then 3-aminopyridine was immobilized with covalent bonds on its surface as a nitrogenous organic compound, in this step we didn't use any organic or toxic substance. This bonding was easily performed due to the presence and reactivity of the epoxy groups in the GO structure. Because of its vast-surface nano-layers, GO could be effective in appropriate dispersion of 3-aminopyridine on its surface and increasing the catalyst performance. The new catalyst was analysed using different microscopic and spectroscopic techniques such as Fourier-transform infrared (FT-IR), field emission scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Our results showed that the distance between GO plates was increased in the presence of the modifying agent. This is due to the placement of the organic compound between the GO sheets. Finally, the ability of our new nano-catalyst in the synthesis of some spiro-indoline-pyranochromene and dihydropyranochromene derivatives was evaluated and acceptable results were obtained. Eight analogous of spiro-indoline-pyranochromene (4a-4 h) were synthesized in high yields and characterized. Using 3-aminopyridine as an organic and efficient catalyst, its stabilization by a simple method on GO, recycling of the catalyst up to 7 times and obtaining a highly pure product were the points that made the present work more attractive.

Recyclable GO-Arginine Hybrids for CO2 Fixation into Cyclic Carbonates

New covalently modified GO-guanidine materials have been realized in a gram-scale synthesis and purified by an innovative microfiltration. The use of these composites in the fixation of CO₂ into cyclic carbonates is demonstrated. Mild operating conditions, high yields (up to 85 %), wide scope (15 examples) and recoverability/reusability (up to 5 cycles) of the material account for the efficiency of the protocol. Dedicated control experiments shed light on the activation modes exerted by GO-l-arginine during the ring-opening/closing synthetic sequence.

Fabrication of Bio-Based Film Comprising Metal Oxide Nanoparticles Loaded Chitosan for Wound Dressing Applications

In the current work, chitosan (CS)-metal oxide nanohybrid (MONH) composites are prepared via combining CS with MONH made of vanadium oxide (V₂O₅), ytterbium trioxide (Yb₂O₃), and graphene oxide (GO) to generate promising wound dressing materials using the film-casting method. The developed nanohybrid@CS was examined using techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TGA). For Yb₂O₃@CS, the surface morphology was shown to be a rough and porous surface with pores that ranged in size from 3.0 to 5.0 µm. For CS with Yb₂O₃, Yb₂O₃/V₂O₅@CS, and Yb₂O₃/V₂O₅/GO@CS, the contact angles were 72.5°, 68.2°, and 46.5°, respectively. When the nanohybrid@CS was in its hydrophilic phase, which is good for absorbing moisture and drugs, there was a notable decrease in angles that tended to rise. Additionally, the inclusion of MONH allowed the cell viability to be confirmed with an IC₅₀ of 1997.2 g/mL and the cell growth to reach 111.3% at a concentration of 7.9 g/mL.