Carbon Research Articles

Three Diterpene Lactones from Andrographis paniculata (Burm. f) Nees In vitro, In silico Assessment of the Anticancer and Novel Liposomal Encapsulation Efficiency

: Three compounds from Andrographis paniculata (Burm. f) Nees leaf were isolated and identified using 1H, 13C, 2D-NMR, and HR-MS techniques for the first time. Compound 3,19-Di-O-acetylandrographolide (3,19-DAA) or (4) is produced by acetylating compound (2). Compounds (2) and (4) have been investigated for their cytotoxic effects on three human cancer cell lines (SK-LU-1, Hela, and HepG2) using the MTT method. Compound (4) demonstrated significant cytotoxicity against all three cancer cell lines, with IC50 values ranging from 8.38 to 10.15 μM. This represents an increase in cytotoxicity of 2.67 to 3.12-fold compared to compound (2). One way to deal with the problem of low water solubility is by encapsulating (4) into liposomes using a thin-film hydration technique. The optimal conditions for maximizing encapsulation efficiency involve molar ratios of phosphatidylcholine, 3,19-DAA, and cholesterol at 4:1:1. Encapsulating compound (4) within nanoscale liposomes increases its water solubility compared to the free form of compound (4). Pose 324 of compound (4) demonstrated the best conformation among 500 docking conformations when docked to enzyme 1T8I in a in silico docking study. The free Gibbs energy and inhibition constant were determined to be -7.09 Kcal/mol and 6.32 μM, respectively. These values help elucidate the strong interaction between compound (4) and the enzyme in the ligand interaction model. The molecular dynamics simulation using Desmond software in the Linux environment was conducted for a duration of 0 to 100 nanoseconds on the complex formed by pose 324 and 1T8I. The results showed effective interactions within the complex, with stability observed from 0 to 60 nanoseconds. Throughout the simulation, specific amino acids such as Ala 499 (involved in 90% of the simulation time with hydrogen bonding via a water bridge) and Thr 501 (involved in 50% of the simulation time with one hydrogen bond via a water bridge) were found to play significant roles. The majority of torsion bondings are C-O bondings in the acetyl group of compound (4), with torsion energy values of 13.47 Kcal/mol. Carbon atom C-29 at position 324 exhibits the highest fluctuation.

Zearalenone degradation by peptide-based enzyme mimics attached membrane reactor: Performance and mechanism

Zearalenone (ZEN) is a nonsteroidal estrogenic mycotoxin with widespread contamination. Inspired by lactone hydrolases, a peptide-based enzyme mimetic material for degrading ZEN was developed by combining serine, histidine and glutamate (S/H/E) catalytic triad with pro-hydrophobic self-assembling sequences and oxyanion hole site. Chitosan hybrid membranes were prepared, followed by immobilizing enzyme mimic on the membrane surface to fabricate biocatalytic membrane reactor. The membrane reactor, with good thermal stability and high catalytic activity after repeated use, can be applied to the degradation of ZEN in food. Computer simulation studies of the degradation mechanism indicated that the carbon atom on the lactone bond within ZEN molecule was susceptible to catalytic triplex attack, leading to lactone bond broken, followed by spontaneous decarboxylation to produce dihydroxyphenyl derivatives with greatly reduced binding capacity to the estrogen receptors. This kind of peptide-based enzyme mimetic material would be very promising in degrading mycotoxins in food safety field.

Exploring the graphitization transformation mechanism of deposited carbon in molten salt electrolysis: A novel insight from molecular structure models

Molten salt electrolysis graphitization is a novel method for the electrochemical graphitization, offering significant technological advantages. Researchers have shown keen interest in preparing graphite materials through molten salt strategies. However, there is still a lack of comprehensive research methodologies at the molecular scale for the removal of heteroatoms and rearrangement of carbon atoms in different amorphous carbon conversion systems. To address the above issue, the deposited carbon (DC, a coking byproduct) was converted into graphitized material (electrolysis products, EP) through the electrochemical method in this study. By processing Transmission Electron Microscope images with Python programming, aromatic skeleton structure information was quantitatively extracted. The evolution of the structure of DC was studied using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Based on information about elemental content, aromatic skeletal structure, and heteroatom functional groups, average chemical structure models were constructed for DC and EP, and relevant chemical bond parameters were statistically analyzed. Then, the influence of the electric field on the structural transformation of amorphous carbon in molten salts was investigated. The research results show that the electric field significantly affects the graphitization transformation process of amorphous carbon in molten salts, enhancing the interaction between calcium ions and DC molecules, increasing the diffusion coefficient of particles in the system, and promoting the formation of more sp2-hybridized carbon atoms, thus forming a more compact aromatic ring network. This study provides a new research method and molecular/atomic-level insights for a deeper understanding of the mechanism of graphitization transformation of amorphous carbon.

Tailoring closed pore structure in phenolic resin derived hard carbon enables excellent sodium ion storage

The existed plenty of oxygen-containing species in phenolic resin easily inhibit the migration and rearrangement of carbon atoms during pyrolysis, which disfavors the formation of pseudo-graphite structure with larger lateral length (La) and hence leads to poor closed pores, accounting for a low capacity and initial Coulombic efficiency (ICE). Herein, hard carbon with rich closed pores and the most suitable pore size and volume is constructed via a two-step carbonization strategy. It is found that the pre-annealing step can effectively decrease oxygen content by changing the interconnection form of molecule chains, which promotes the growth of La during post-carbonization process, accelerating the formation of closed pores. Besides, with decreasing oxygen content, closed pore size gradually increases, while closed pore number and volume both first increase and then decrease, unveiling that an excessive high and too low oxygen content are unfavorable for the formation of ideal closed pores, resulting from an unsuitable La size. Therefore, the resulting sample, featured by the optimal balance between closed pore number, size (2.52 nm), and volume (0.215 cm3 g−1), delivers a high capacity of 351 mAh g−1 along with an excellent ICE of 83 %.

Structural basis for substrate flexibility of the O-methyltransferase MpaG' involved in mycophenolic acid biosynthesis.

MpaG' is an S-adenosyl-L-methionine (SAM)-dependent methyltransferase involved in the compartmentalized biosynthesis of mycophenolic acid (MPA), a first-line immunosuppressive drug for organ transplantations and autoimmune diseases. MpaG' catalyzes the 5-O-methylation of three precursors in MPA biosynthesis including demethylmycophenolic acid (DMMPA), 4-farnesyl-3,5-dihydroxy-6-methylphthalide (FDHMP), and an intermediate containing three fewer carbon atoms compared to FDHMP (FDHMP-3C) with different catalytic efficiencies. Here, we report the crystal structures of S-adenosyl-L-homocysteine (SAH)/DMMPA-bound MpaG', SAH/FDHMP-3C-bound MpaG', and SAH/FDHMP-bound MpaG' to understand the catalytic mechanism of MpaG'and structural basis for its substrate flexibility. Structural and biochemical analyses reveal that MpaG' utilizes the catalytic dyad H306-E362 to deprotonate the C5 hydroxyl group of the substrates for the following methylation. The three substrates with differently modified farnesyl moieties are well accommodated in a large semi-open substrate binding pocket with the orientation of their phthalide moiety almost identical. Based on the structure-directed mutagenesis, a single mutant MpaG'Q267A is engineered with significantly improved catalytic efficiency for all three substrates. This study expands the mechanistic understanding and the pocket engineering strategy for O-methyltransferases involved in fungal natural product biosynthesis. Our research also highlights the potential of O-methyltransferases to modify diverse substrates by protein design and engineering.

Molecular dynamics investigation on the mechanical properties of a novel 2D carbon allotrope: Planar net-τ nanoribbon

This study is focused on investigating of the mechanical properties of a recently discovered two-dimensional carbon allotrope, known as planar net-τ, through molecular dynamics simulations. The planar net-τ is a unique and unexplored carbon configuration known for its intricate network of carbon atoms arranged in a planar lattice. The study aims to improve understanding of the mechanical properties of planar net-τ. This includes investigating parameters such as Young's modulus, fracture strain, ultimate strength, strain at ultimate stress, and the stress-strain curve. This study achieves this by deliberately manipulating of variables, such as introduction of vacancy defects, altering temperature, and dimensional adjustments. Vacancy defects in 2D carbon allotropes significantly impair their mechanical properties, reducing stiffness and increasing mechanical failure. Changes in dimensions further impact these properties through contraction, affecting strength and elasticity. These results highlight the anisotropic nature of these structures.

High-value multilayer graphene oxide prepared by catalytic pyrolysis of petroleum tar and applications: Trash to treasure

Petroleum tar (PT), a by-product of heavy oil refining, poses significant environmental challenges due to its high production volume and associated pollution risks. This study presents an innovative approach for the catalytic conversion of PT into multilayer graphene oxide using nickel foam (NiF) as a catalyst at reaction temperatures of 500 °C and 700 °C (GT/Ni500 and GT/Ni700). The process effectively decomposes PT and facilitates the structured rearrangement of carbon atoms into graphene layers. Comprehensive characterization techniques, including SEM-EDS, HRTEM, BET, XRD, XPS, and Raman spectroscopy, confirm the formation of high-quality graphene oxide. The synthesized GT/Ni700 material exhibits remarkable electrochemical performance with a specific capacitance of 3.34F/g. GT/Ni500 shows adsorption capacities of 59.86 mg/g for Pb2+ and 56.84 mg/g for Cu2+. Life Cycle Assessment reveals a substantial reduction in the carbon footprint, with CO2 equivalents for GT/Ni500 and GT/Ni700significantly lower than traditional methods, at 17.64 kg/CO2eq and 14.03 kg/CO2eq, respectively, representing a reduction of over 50 %. This study not only offers a sustainable pathway for PT utilization but also provides advanced materials with dual utility in electrochemical applications and heavy metal adsorption, contributing to environmental remediation and reducing reliance on non-renewable resources.

1,3,4-Oxadiazole and Its Analogs: Recently Adopted Synthetic Approaches and Interaction with Targets

: 1,3,4-Oxadiazole is a five-membered heterocyclic compound with one oxygen, two nitrogen, and two carbon atoms arranged in a ring. Several research reports, patents, and marketed drugs have already established 1,3,4-oxadiazole and its analog as potential molecules having a diverse range of pharmacological activities. In this review, we focused on recently acknowledged straightforward synthesis approaches for 1,3,4-oxadiazole and its analogs. Additionally, interactions of the 1,3,4-oxadiazole derivative with different biological targets (enzymes and receptors) have been described. The present findings discussed in this review analysis will aid researchers in conducting future research on 1,3,4-oxadiazole.

Green Nanotech: A Review of Carbon-Based Nanomaterials for Tackling Environmental Pollution Challenges

In recent times, nanotechnology has experienced widespread acclaim across diverse sectors, including but not limited to tissue engineering, drug delivery systems, biosensors, and the mitigation and monitoring of environmental pollutants. The unique arrangement of carbon atoms in sp3 configurations within carbon nanomaterials endows them with exceptional physical, mechanical, and chemical characteristics, driving them to the forefront of materials research. Their appeal lies in their efficacy as superior adsorbents and their exceptional thermal resistance, making them versatile in various applications. The present review extensively explores a range of carbon-based nanomaterials, delving into their synthesis methods and examining their multifaceted applications in addressing environmental pollutants. It is crucial to emphasize that the popularity of carbon-based nanomaterials arises from their potential to serve as superior adsorbents, coupled with their outstanding thermal resistance properties. These attributes contribute to their applicability in diverse environmental contexts. Looking ahead, carbon-based nanomaterials are poised to emerge as environmentally friendly and cost-effective materials, representing promising and potential avenues for the advancement of sustainable technology.

Studies on the characteristics of polycyclic aromatic hydrocarbons accumulation in lipids and the disturbance of lipid metabolism of Ruditapes philippinarum

Polycyclic aromatic hydrocarbons (PAHs) constitute a class of persistent organic pollutants with strong lipophilicity, which readily accumulate within organisms and have the effect to induce disorders in lipid metabolism. The present study aimed to investigate the accumulation localization and pattern of PAHs in Ruditapes philippinarum, and to reveal the association between PAHs and lipids metabolism. The 21-day exposure experiment was conducted using a mixture of phenanthrene, chrysene, and benzo[a]pyrene (the proportion is 1:1:1) at concentrations of 0.4 μg/L, 2 μg/L, and 10 μg/L. The tissue distribution of PAHs indicated that the digestive gland was the primary site of PAHs accumulation. Meanwhile, fluorescence colocalization suggested that PAHs primarily accumulated within the lipid droplets of digestive gland cells. This study further determined the transcriptomic and lipidomic profiles of the digestive gland to analyze the key genes involved in disrupted lipid metabolism and the major lipids affected. Lipidomic analysis identified the key differential metabolites as triglycerides (TGs). Furthermore, TGs were upregulated in the digestive gland had a total carbon atom number of 50–64 and a total number of 3–9 double bonds in the acyl side chains. Biochemical analysis experiments and oil red O stained frozen sections confirmed that the content of TGs steadily increased in various tissues during the experiment, leading to an elevated digestive gland index. Changes of lipid metabolism associated genes expression level also indicated that the synthesis of lipid in digestive gland were up-regulated while the decomposition was down-regulated. This study is the first to demonstrate the cellular localization of PAHs accumulation in bivalves and confirms the pattern of variation in TGs, providing new insights into the mechanisms of PAHs bioaccumulation and lipid metabolism disruption.

Synthesis of 5-(4-Formylphenyl)barbituric Acid to Access Enolizable Chromophoric Barbituric Acids

AbstractBarbituric acids mono-substituted at the 5-position show keto–enol tautomerism. In the keto form, conjugation to an aryl substituent is interrupted due to the sp³-hybridized carbon atom at the 5-position of barbituric acid. The enol form generates a conjugated π-system to the aryl substituent and acts as an electron-donating group. If the aryl substituent is electron-deficient, a push-pull system is generated that shows typical UV/Vis absorption. These types of compounds are difficult to access synthetically due to their intrinsic convertibility. The synthesis of barbituric acids with a 4-formylphenyl functionality at the 5-position is reported. This compound, 5-(4-formylphenyl)barbituric acid, could be used to introduce extended π-systems with electron-withdrawing groups in great variety by simple condensation reactions. We demonstrate this by a Horner–Wadsworth–Emmons reaction that forms the enolizable dye (E)-5-(4-(4-nitrostyryl)phenyl)barbituric acid.

Engineering of (−)‐Limonene‐3‐Hydroxylase to Enhance Its Regioselectivity for Biosynthesis of (−)‐Menthol

AbstractThere is high market demand for (−)‐menthol because of its unique aroma and cooling properties. The first bottleneck encountered in the biosynthesis of (−)‐menthol in Escherichia coli is the low hydroxylation efficiency of (−)‐limonene‐3‐hydroxylase. Few known enzymes can hydroxylate the third carbon atom of (−)‐limonene. In this work, initially, we searched for new enzymes and screened a library of cytochrome P450BM3 variants aiming to improve catalysis of this reaction, but did not identify any variants with improved activity or regioselectivity. Then, through protein engineering of a cytochrome P450 monooxygenase variant from Pseudomonas putida (PpcamY96F/V247L), we obtained variant PpcamF87W/Y96F/L244I/V247L/V396A with regioselectivity of 93% (starting from 70%) toward (−)‐limonene without losing activity. Because of the improvement in regioselectivity, its turnover number was 1.5 times that of the starting enzyme. We analyzed the reasons for the improvement through molecular dynamics simulations. The new variant also exhibited 95% regioselectivity toward (+)‐limonene. This enzyme variant can be applied in biosynthesis of (−)‐menthol.

Molecular dynamics study of the influence of carbon impurity on austenite nanoparticles crystallization during rapid cooling

The molecular dynamics method was used to study the structure formation during austenite nanoparticles crystallization in the presence of carbon impurities. The paper describes the dependence of the melt cooling rate, particle size, concentration of carbon atoms in the particle on the resulting structure features during crystallization and temperature of the crystallization onset. Formation of the nanocrystalline structure of nanoparticles can be controlled by varying the cooling rate and introducing a carbon impurity: at a cooling rate above 1013 K/s in the model used, crystallization did not have time to occur; at a rate below 5·1012 K/s, the austenite particle crystallized to form a nanocrystalline structure. At the same time, with a decrease in the cooling rate, a decrease in the density of defects in the final structure was observed. At a rate of 5·1011 K/s or less, crystallization of carbon-free particles took place with the formation of low-energy grain boundaries (with a high density of conjugate nodes: special boundaries, twins). The crystallization temperature during cooling at a rate below 1012 K/s is inversely proportional to the particle diameter: as the particle size decreases, the proportion of free surface increases, which leads to a decrease in the probability of crystalline nuclei formation. In addition, the crystallization temperature increases with a decrease in the cooling rate. The introduction of a carbon impurity led to a decrease in the crystallization temperature of nanoparticles: in the presence of 10 at. %. As a percentage of carbon, it decreased by about 200 K for particles of different sizes. Carbon atoms often formed clusters consisting of several carbon atoms. Such clusters distorted the resulting crystal lattice of metal around them, preventing crystallization. In the presence of a carbon impurity, the final structure of the crystallized particles contained a higher density of grain boundaries and other defects. Carbon atoms, especially clusters of them, were fixed mainly at grain boundaries and triple joints.

Recovering Valuable Chemicals from Polypropylene Waste via a Mild Catalyst-Free Hydrothermal Process.

Waste polypropylene (PP) presents a significant environmental challenge, owing to its refractory nature and inert C-C backbone. In this study, we introduce a practical chemical recovery strategy from PP waste using a mild catalyst-free hydrothermal treatment (HT). The treatment converts 64.1% of the processed PP into dissolved organic products within 2 h in an air atmosphere at 160 °C. Higher temperatures increase the PP conversion efficiency. Distinct electron absorption and emission characteristics of the products are identified by spectral analysis. Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) reveals the oxidative cracking of PP into shorter-chain homologues (10-50 carbon atoms) containing carboxylic and carbonyl groups. Density functional theory (DFT) calculations support a reaction pathway involving thermal C-H oxidation at the tertiary carbon sites in the polymer chain. The addition of 1% H2O2 further enhances the oxidation reaction to produce valuable short-chain acetic acids, enabling gram-scale recycling of both pure PP and disposable surgical masks from the real world. Techno-economic analysis (TEA) and environmental life cycle costing (E-LCC) analysis suggest that this hydrothermal oxidation recovery technology is financially viable, which shows significant potential in tackling the ongoing plastic pollution crisis and advancing plastic treatment methodologies toward a circular economy paradigm.

An investigation of the mechanism of emulsion stabilization in octenyl succinic anhydride-modified tamarind seed polysaccharide

Previous studies have shown that octenyl succinic anhydride-modified tamarind seed polysaccharide (OTSP) is an effective emulsion stabilizer. In this study, the fine structure and interfacial behavior of OTSP were investigated using a variety of methods to elucidate its mechanism for stabilizing emulsions. First, the results of nuclear magnetic resonance indicated that the esterification reaction occurred at the 6th carbon atom of glucose, which was not replaced by xylose in the main chain of TSP. Then, the studies of the interfacial behavior showed that OTSP adsorbed more at the oil-water interface than TSP, and that the intermolecular interactions of OTSP were stronger than those of TSP. The adsorption of OTSP at the interface was dominated by diffusion. Compared to TSP, OTSP formed a denser and more flexible interfacial layer and was resistant to large deformations and high-frequency perturbation. Molecular dynamics simulations revealed the presence of an Ω-like structure in the OTSP molecule. This structure reduced the degree of ordering of its molecular chains, resulting in a more flexible and looser structure that facilitated the rearrangement of OTSP molecules at the interface. The hydrophobic groups anchored the OTSP to the surface of the oil droplets, fixing them in the network structure, further restricting droplet movement and thus improving emulsion stability. The results of this study contribute to the understanding of the mechanism of polysaccharide-stabilized emulsion, which is of great significance in promoting the application of TSP in the food industry.

Structural and phonon transport analysis of surface-activated bonded SiC-SiC homogenous interfaces

To avoid the interfacial thermal stress problem caused by high temperature, room temperature bonding techniques such as surface-activated bonding (SAB) are currently receiving widespread attention. However, the thermal boundary resistance (TBR) is challenging in reaching the theoretical value because the bombardment of the surface by energetic particle beams causes the formation of amorphous layers. In this paper, we have prepared SiC/SiC interfaces by surface-activated bonding and tried to explain the effect of the interfacial amorphous layer on the thermal properties. The results show that an amorphous layer of about 9 nm was formed at the SiC/SiC interface, mainly composed of carbon atoms. Molecular dynamics simulations derive an effective thermal boundary resistance (TBReff) of 4.78 m2K/GW for this interface, where the TBR of SiC/a-C is only approximately 0.50 m2K/GW. The TBReff with 30 % Fe after modification increased to 6.74 m2K/GW. The lower TBR between SiC/a-C can be attributed to coupling extended modes (EMs) and localized modes (LMs) at the interface and acting as a phonon bridge. In addition, the bulk thermal resistance of the amorphous layer accounts for 79.3 % of the TBReff. Besides, the molecular dynamics results show that the decrease in the thickness of the amorphous layer can significantly reduce the TBReff. As the thickness of the amorphous layer tends to zero, the TBReff is almost close to zero. The above conclusions will be beneficial to understanding the main factors influencing the thermal properties in the SiC/SiC interface, which point out the way for the subsequent improvement of the interfacial thermal conductivity.

The amorphous porous carbon incorporating 1D-nanofiber as electroactive biomass with integrated pyrolysis for high-performance symmetrical supercapacitors

Supercapacitors widely use electroactive biomass as a carbon electrode for energy conversion and storage. In this research, carbon electrodes were fabricated using Nipah mesocarp (NM) as the base material for symmetric supercapacitor cells. NM sample was physically and chemically activated using KOH 0.5 M and CO2 at varying temperatures of 700 °C, 800 °C, and 900 °C. Physical activation is integrated with the carbonization process in a nitrogen atmosphere. A sample obtained by subjecting CO2 to an activation temperature of 800 °C yields a high purity of 90 % carbon atoms with a 1D superstructure (nanofiber structure), which has a high specific surface area of 676 m2g−1 and a high specific capacitance of 300 Fg−1 at 1 Ag−1. Supercapacitors assembled using NM electroactive biomass can achieve a high power density of 146 W kg−1 and an energy density of 42 Wh kg−1 in a 1 M H2SO4. This electroactive biomass has great potential to be considered as an electrode material for energy storage devices or conversions that are abundantly available in the universe, renewable, and economical.

Amorphous Carbon Nitride Films: Surface and Subsurface Composition and Bonding.

To obtain quantitative information about the composition and bonding of atoms located at and beyond the analyzed solid surface nondestructively, we applied angle-resolved X-ray photoelectron spectroscopy aided by the maximum entropy method to air-exposed amorphous carbon nitride films deposited by pulsed laser deposition of diamond-like carbon modified by low-energy nitrogen ion bombardment during film growth. We demonstrate that the composition, chemical bonding, and mass density vary significantly from the top surface to a shallow subsurface region. The analyzed samples, in a shallow surface region of ∼1 nm, are composed of oxygen, nitrogen, hydrogen, and mostly carbon in sp2 hybridization. In a deeper region, the C sp3 content increases substantially going to a maximum, whereas the nitrogen percentage decreases to a minimum, then increases, and tends to saturate. Special attention has been paid to in-depth distributions of carbon atoms in trigonal and tetragonal arrangements because they specify numerous physical and chemical properties of carbon-based materials. These results indicate that the interaction of DLC:N surfaces with surroundings can be influenced, barring oxygen and nitrogen, by sp2-bonded carbon atoms located near the surface of the samples. The obtained results can be useful for developing a deeper understanding of the interaction between DLC:N layer surfaces and their surroundings and particularly with living tissue.

Silver-Catalyzed Single-Carbon Insertion of Indoles with Acetophenone N-Triftosylhydrazones.

Here, we report a silver carbene-enabled single-carbon insertion reaction of indoles via a one-pot, two-step sequence to deliver a dearomative quaternary center quinoline scaffold in a modular fashion. Specifically, we used N-triftosylhydrazones as masked donor-donor carbene precursors that facilitate the insertion of carbon atoms bearing various functional groups to the library of functionalized quinoline. Experimental and DFT evidence support the transient presence of a cyclopropane species and removal of protecting groups.

First direct detection of large polycyclic aromatic hydrocarbons on asteroid (162173) Ryugu samples: An interstellar heritage

AbstractPolycyclic aromatic hydrocarbons (PAHs) are considered major players in the physics and chemistry of star‐ and planet‐forming regions. The interstellar PAH hypothesis is based on our understanding of the origin of the aromatic infrared bands (AIBs), a set of bright emission features that are now the focus of observations by the James Webb telescope. While AIB carriers are expected to be large free PAHs (50 carbon atoms or more), laboratory analysis of primitive carbonaceous chondrites (CCs) has mainly revealed relatively small PAHs, up to 24 carbon atoms. In this study, we present a comprehensive analysis of aromatic species in bulk samples from the carbonaceous asteroid Ryugu using a surface mass spectrometry technique provided by two‐step laser desorption ionization. The resulting molecular distribution differs significantly from that obtained for a sample from the CC Orgueil, revealing aromatic species extending up to 61 carbon atoms. The species identified are composed of both peri‐condensed PAHs and non‐condensed aromatics. These results directly support the interstellar PAH hypothesis and open up new perspectives on the formation and evolution of organic matter in star‐forming regions and in the solar nebula.Key Points First direct detection of free aromatic species of large sizes with up to 61 carbon atoms in primitive extraterrestrial matter by applying a highly sensitive two‐step laser mass spectrometry analysis to grain samples from the carbonaceous asteroid Ryugu (Hayabusa2 mission). First direct support for the interstellar polycyclic aromatic hydrocarbon (PAH) hypothesis, according to which large free PAHs are responsible for the aromatic emission bands that are major infrared features currently observed by the James Webb Space Telescope. The large aromatic species detected are present in trace amounts and future research is needed to develop sensitive techniques for studying these compounds in sample return missions and meteorites.