Frontiers in Chemistry最新文献

Introduction: This study explores potential application of silver nanoparticles (AgNPs) to treat periodontal infection using Azadirachta indica leaf extract. The eco-friendly green synthesis process uses Azadirachta indica as a natural stabilizer and reducer, allowing AgNPs to be formed.

Methods: Experimental AgNPs were characterized through transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Zeta potential, ultraviolet-visible spectroscopy (UV-Vis) etc. The antimicrobial, antioxidant potential of AgNPs was tested to identify its efficacy against periodontal infections.

Results and discussion: AgNPs were found spherical, nanosized (86 nm), with negative surface charge (-26.9 mV). TEM study depicted clear formation of discrete nanosize particles with smooth surface texture. Results showed strong antibacterial and anti-oxidant action of experimental AgNPs, preventing biofilm growth and bacterial viability. A higher binding affinity was observed between Quercetin and the selected protein, which is implicated in bacterial growth and biofilm formation on teeth. The study suggests that Azadirachta indica derived AgNPs could be a safe, efficacious, and eco-friendly alternative in place of conventional therapies to treat periodontal infection. Future in vivo studies are however warranted.

Quantum dots (QDs), also known as nanoparticle-based fluorescent probes, are luminescent semiconductor particles with a size range of 2-20 nm. The unique optical and electronic capabilities of QDs have led to expanded applications in several fields such as optoelectronics, transistors, sensors, photodetection, catalysis, and medicine. The distinct quantum effects of nanocrystals can be controlled by changing their sizes and shapes using a variety of top-down and bottom-up tactics. QDs were traditionally fabricated using complex, expensive, toxic, and aggressive chemical techniques, which limited their application in a variety of disciplines. A unique approach for the biosynthesis of nanomaterials has been devised, which employs living organisms in the synthesis process and adheres to green chemistry principles. Biogenic QDs have favorable physicochemical features, biocompatibility, and fewer cytotoxic effects as a result of using natural biomolecules and enzymatic processes for mineralization, detoxification, and nucleation of metals and nonmetals to synthesize QDs. This is the first comprehensive review of its kind that highlights the synthesis of several doped and undoped QDs, including graphene QDs, carbon dots, silicon QDs, N/S-CDs, silver-CDs, cadmium-selenium QDs, and zinc oxide QDs, exclusively using photoautotrophic algae and plants. The different plausible mechanisms behind phyco- and phyto-fabrication of QDs are also discussed in detail along with their applications that include detection of organic and inorganic compounds, degradation of hazardous dyes, free radical scavenging, antimicrobial activity, cytotoxicity and bioimaging. Thus, this review aims to give valuable insights for the rational fabrication of photoluminescent nanomaterials with tunable structural and functional properties.

Pathogen-induced infections and the rise of antibiotic-resistant bacteria, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), pose significant global health challenges, emphasizing the need for new antimicrobial strategies. In this study, we synthesized graphene oxide (GO)-based composites functionalized with silver nanoparticles (AgNPs) and copper nanoparticles (CuNPs) as potential alternatives to traditional antibiotics. The objective is to assess the antibacterial properties of these composites and explore their efficacy against E. coli and S. aureus, two common bacterial pathogens. The composites are prepared using eco-friendly and conventional methods to ensure effective nanoparticle attachment to the GO surface. Structural and morphological characteristics are confirmed through SEM, AFM, EDS, XRD, UV-vis, FTIR, and Raman spectroscopy. The antibacterial efficacy of the composites is tested through disk diffusion assays, colony-forming unit (CFU) counts, and turbidimetry analysis, with an emphasis on understanding the effects of different nanoparticle concentrations. The results demonstrated a dose-dependent antibacterial effect, with GO/AgNP-1 showing superior antibacterial activity over GO/AgNP-2, particularly at lower concentrations (32.0 μg/mL and 62.5 μg/mL). The GO/CuNP composite also exhibited significant antibacterial properties, with optimal performance at 62.5 μg/mL for both bacterial strains. Turbidimetry analysis confirmed the inhibition of bacterial growth, especially at moderate concentrations, although slight nanoparticle aggregation at higher doses reduced efficacy. Lastly, both GO/AgNP and GO/CuNP composites demonstrated significant antibacterial potential. The results emphasize the need to fine-tune nanoparticle concentration and refine synthesis techniques to improve their efficacy, positioning these composites as strong contenders for antimicrobial use.

Nicotine is a chiral alkaloid; nitrogen-containing organic compound that occurs naturally. (S)-nicotine is extracted from Tobacco plants and used as the key addictive ingredient in many smoking products. Synthetic nicotine has gained the interest of many smoking product manufacturers over the last few decades due to the ease and low cost of manufacturing. Another claimed advantage of synthetic nicotine is the absence of genotoxic impurities that form during the extraction process of nicotine. These impurities are other plant alkaloids, phenolic compounds, and heavy metals. Additionally, the U. S. FDA has implemented new regulations on the quality control of synthetic nicotine. However, only a very few research articles have been published on assessing the complete impurity profile of synthetic nicotine. Therefore, the need to know the composition difference between tobacco-extracted nicotine vs. synthetic nicotine is highly necessary. In this research study, the impurity profile of thirteen different lots of synthetic nicotine was compared with fourteen lots of nicotine extracted from plants using in-house analytical methods. First, the samples were tested for other alkaloids and phenols by reversed-phase High-Performance Liquid Chromatography (HPLC). Second, the chiral purity was analyzed by normal phase HPLC. Third, lead and arsenic content were tested by atomic absorption and fluorescence spectrometry. Fourth, nicotine-specific nitrosamines were tested by LC-MS. The reversed phase HPLC data suggested similar quantities of total impurities in both synthetic and tobacco-extracted nicotine (0.1%). However, synthetic nicotine lacks some impurities such as cotinine, nornicotine, and nicotine-N-oxide. Additionally, the synthetic nicotine lots used in this study have high enantiomeric purity similar to the tobacco-extracted nicotine.

The conductance of a tunneling electron through a π-conjugated molecule may be affected by the presence of different pathways in the orbital structure of the molecule, resulting in the constructive or destructive interference of the molecular wave function. This quantum interference (QI) directly translates into enhancement or suppression of conductance and offers the possibility of controlling this phenomenon through tailored synthesis. Hence, we set up synthetic methodologies to access a series of thiophene-fused helicenes with a well-defined positioning of the sulfur atoms, which control the occurrence of conducting, linearly conjugated as well as disrupted, cross-conjugated pathways. We describe these synthetic strategies and relate the expected electronic transport through our molecules to three key variables: a) the exo-/endo-topology of the S atom within the ring; b) the parity (odd/even) of the overall number of rings conforming to the helicene; and c) the size of the circuit. This series ranks from [7] to [11] fused rings, having both exo-, endo-, or mixed exo-endo-topology. Comparison of homologous dithiahelicenes with size-tunable highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energies allows us to isolate the key variable of the bond topology from other electronic properties and face the study of QI in helically conjugated molecules. Understanding and tuning the conductance in such molecular solenoids is the main purpose of this work.

Copper-based materials play a vital role in the electrochemical transformation of CO₂ into C₂/C₂₊ compounds. In this study, cross-sectional octahedral Cu₂O microcrystals were prepared in situ on carbon paper electrodes via electrochemical deposition. The morphology and integrity of the exposed crystal surface (111) were meticulously controlled by adjusting the deposition potential, time, and temperature. These cross-sectional octahedral Cu₂O microcrystals exhibited high electrocatalytic activity for ethylene (C₂H₄) production through CO₂ reduction. In a 0.1 M KHCO₃ electrolyte, the Faradaic efficiency for C₂H₄ reached 42.0% at a potential of -1.376 V vs. RHE. During continuous electrolysis over 10 h, the FE (C₂H₄) remained stable around 40%. During electrolysis, the fully exposed (111) crystal faces of Cu₂O microcrystals are reduced to Cu⁰, which enhances C-C coupling and could serve as the main active sites for catalyzing the conversion of CO₂ to C₂H₄.

Novel perovskites pertain to newly discovered or less studied variants of the conventional perovskite structure, characterized by distinctive properties and potential for diverse applications such as ferroelectric, optoelectronic, and thermoelectric uses. In recent years, advancements in computational methods have markedly expedited the discovery and design of innovative perovskite materials, leading to numerous pertinent reports. However, there are few reviews that thoroughly elaborate the role of computational methods in studying novel perovskites, particularly for state-of-the-art perovskite categories. This review delves into the computational discovery of novel perovskite materials, with a particular focus on antiperovskites and chalcogenide perovskites. We begin with a discussion on the computational methods applied to evaluate the stability and electronic structure of materials. Next, we highlight how these methods expedite the discovery process, demonstrating how rational simulations contribute to researching novel perovskites with improved performance. Finally, we thoroughly discuss the remaining challenges and future outlooks in this research domain to encourage further investigation. We believe that this review will be highly beneficial both for newcomers to the field and for experienced researchers in computational science who are shifting their focus to novel perovskites.

The Yamaguchi reagent, based on 2,4,6-trichlorobenzoyl chloride (TCBC) and 4-dimethylaminopyridine (DMAP), is an efficient tool for conducting the intermolecular (esterification) reaction between an acid and an alcohol in the presence of a suitable base (Et₃N or ⁱ Pr₂NEt) and solvent (THF, DCM, or toluene). The Yamaguchi protocol is renowned for its ability to efficiently produce a diverse array of functionalized esters, promoting high yields, regioselectivity, and easy handling under mild conditions with short reaction times. Here, the recent utilization of the Yamaguchi reagent was reviewed in the synthesis of various natural products such as macrolides, terpenoids, polyketides, peptides, and metabolites.

With the aim to develop a FRET-based viscosity sensor, two dyad molecules, 4 and 5, comprising tetraarylpyrrolo[3,2-b]pyrrole (TAPP) (donor) and naked boron-dipyrromethene (BODIPY) dyes (acceptor), were designed. Dyads were synthesized via acid-catalyzed multicomponent reactions followed by Sonogashira coupling. In both dyads, the BODIPY and TAPP moieties are linked through phenylethynyl groups, which allow free rotation of the BODIPY dyes; that is, they can act as molecular rotors. This was supported by X-ray crystallographic and DFT-optimized structures. Spectroscopic studies also confirmed the presence of both TAPP and BODIPY dyes in dyads with no electronic interactions that are suitable for fluorescence resonance energy transfer (FRET). Very high energy transfer efficiency (ETE >99%) from the donor TAPP moiety to the acceptor BODIPY moiety on excitation at the TAPP part was observed. However, due to the non-fluorescent nature of naked BODIPY dyes, no fluorescence emission was observed from the BODIPY moiety in both dyads. With increasing solvent viscosities, emission from the BODIPY moieties increases due to the restricted rotation of the BODIPY moieties. Plotting the logarithms of the fluorescent intensity of dyad 5 and the viscosity of the solution showed a good linear correlation obeying a Förster-Hoffmann equation. Non-fluorescent dyad 5 in methanol became greenish-yellow fluorescent in a methanol/glycerol (1:1) solvent. Furthermore, with an increase in the temperature of the methanol/glycerol (1:1) system, as the viscosity decreases, the fluorescence also starts decreasing. Thus, dyad 5 is capable of sensing the viscosity of the medium via a FRET-based "Off-On" mechanism. This type of viscosity sensor with a very large pseudo-Stokes shift and increased sensitivity will be useful for advancing chemo-bio sensing and imaging applications.

Dermal fibroblasts play a crucial role in the formation of granulation tissue in skin wounds. Consequently, the differentiation, migration, and proliferation of dermal fibroblasts are considered key factors in the skin wound healing process. However, in patients with diabetic foot ulcers, the proliferation and migration of fibroblasts are impaired by reactive oxygen species and inflammatory factors impair. Therefore, a novel magnetic gelatin-hesperidin microrobots drug delivery system was developed using microfluidics. The morphology, motility characteristics, and drug release of the microrobot were assessed, along with its impact on the proliferation and migration of human dermal fibroblasts under high-glucose conditions. Subjected to a rotating magnetic field, the microrobots exhibit precise, controllable, and flexible autonomous motion, achieving a maximum speed of 9.237 μm/s. In vitro drug release experiments revealed that approximately 78% of the drug was released within 30 min. It was demonstrated through cellular experiments that the proliferation of human dermal fibroblasts was actively promoted by the nanorobot, the migration ability of fibroblasts in a high-glucose state was enhanced, and good biocompatibility was exhibited. Hence, our study may provide a novel drug delivery system with significant potential for promoting the healing of diabetic foot wounds.