Aliphatic Molecules Research Articles

Exceptional preservation of organic matter and iron-organic colloidal mineralization in hydrothermal black smoker-type sulfide mineralization from the Paleoarchean seafloor

Fossil organic matter (OM) in Paleoarchean rocks is an invaluable tracer of ancient life, yet it is often contentious due to low preservation potentials of its original organic molecular characteristics under generally high metamorphic grades. This study reports on exceptionally preserved OM within black smoker-type sulfide mineralizations from the 3.24 billion-years-old Sulphur Springs volcanic-hosted massive sulfide deposit, East Pilbara Terrane, northwestern Australia. Fine scale mineralogical and organic molecular variations – documented by SEM and TEM techniques, Raman and FTIR Spectroscopy, as well as ToF-SIMS analysis – trace the formation of millimetre-scale pyritic hydrothermal orifices. Overmature OM (≳200–250 °C) enriched in aromatic hydrocarbons occurs within earliest formed colloform-banded pyrite that could have precipitated at high temperature upon mixing of hot hydrothermal fluids with cold seawater. In contrast, mature OM (within the catagenesis window; ∼100–150 °C) with lower proportions of aromatic hydrocarbons occasionally occurs alongside pyrite within barite near the inner paleofluid conduits of the hydrothermal orifices. A deposition of this OM generation from cooler fluids enriched in sulfate during waning hydrothermal activity is corroborated by its association with original mineralogy, particularly the occurrence of isolated nanoinclusions of OM within hydrothermal barite away from grain boundaries or fissures and cracks, which renders impossible an origin from post-depositional hydrocarbon migration. When compared to the overmature OM within colloform-banded pyrite, the better-preserved inner OM not only contains less abundant, smaller, and less ordered aromatic hydrocarbons, but also higher amounts of aliphatic molecules with longer chain lengths and higher proportions of carbonyl and amide functional groups. Although the latter characteristics are consistent with contributions by microbial biomass, abiotic origins are equally plausible because hydrothermal processes can produce OM with similar organic molecular attributes. Irrespective of these uncertainties on the ultimate sourcing of OM, common intergrowths of the cooler OM with nanoscopic iron oxides – hematite and lesser magnetite – hint at its hydrothermal deposition from colloidal particles that have been stabilized by iron-organic complexation. Further research is required to ascertain the significance of this process for the hydrothermal cycling and release of organic carbons and bound iron into the Paleoarchean oceans. Collectively, our results show that ancient marine hydrothermal systems can preserve OM with differing degrees of thermal degradation, which allows for insights into its sourcing, cycling, and deposition.

Biosignatures Preserved in Carbonate Nodules from the Western Qaidam Basin, NW China: Implications for Life Detection on Mars.

The search for organic matter on Mars is one of the major objectives of Mars exploration. However, limited detection of organic signals by Mars rovers to date demands further investigation on this topic. The Curiosity rover recently discovered numerous nodules in Gale Crater on Mars. These nodules have been considered to precipitate in the neutral-to-alkaline and saline diagenetic fluids and could be beneficial for organic preservation. Here, we examine this possibility by studying the carbonate nodules in the western Qaidam Basin, NW China, one of the terrestrial analog sites for Mars. Fourier transform infrared spectra of the carbonate nodules reveal that the aliphatic and aromatic molecules can be readily preserved inside nodules in Mars-like environments. The chain-branching index of the Qaidam nodules suggests that the diagenetic fluids where nodules precipitated were able to support diverse microbial communities that could vary with the water salinity. Findings of this study provide new perspectives on the astrobiological significance of nodules in Gale Crater and the further detection of organic matter on Mars.

The Influence of Solvent and Extraction Time on Yield and Chemical Selectivity of Cuticular Waxes from Quercus suber Leaves

The cuticular lipid compounds, usually named cuticular waxes, present in the cuticular layering of Quercus suber adult leaves were extracted with solvents of different polarities (n-hexane, dichloromethane and acetone) and analysed by GC–MS. Q. suber leaves have a substantial cuticular wax layer (2.8% of leaf mass and 239 μg/cm2), composed predominantly by terpenes (43–63% of all compounds), followed by aliphatic long chain molecules, mainly fatty acids, and by smaller amounts of aliphatic alcohols and n-alkanes. The major identified compound was lupeol (1.2% of leaves in n-hexane extract). The recovery and composition of cuticular lipids depended on the solvent and extraction time. The non-polar or weak polar solvents n-hexane and dichloromethane extracted similar lipid yields (77% and 86% of the total extract, respectively) while acetone solubilised other cellular compounds, namely sugars, with the lipid compounds representing 43% of the total extract. For cuticular lipids extraction, solvents with a low polarity such as n-hexane are the more suitable with an adequate extraction duration, e.g., n-hexane with a minimum extraction of 3 h.

Dynamics of Site Selectivity in Dissociative Electron Attachment in Aromatic Molecules

Dissociative electron attachment has shown site selectivity in aliphatic molecules based on the functional groups present in them. This selectivity arises from the core excited resonances that have excited parent states localized to a specific site of the functional group. Here, we show that such site selectivity is also observed in the amine group when present in aromatic molecules. However, the proximity of the aromatic ring to the functional group under investigation has a substantial effect on the dissociation dynamics. This effect is evident in the momentum distribution of the hydride ions generated from the amine group. Our results unravel the hitherto unknown facets of the site selectivity in aromatic organic molecules.

Synergistic effect of ferrous ion-activated hydrogen peroxide and persulfate on the degradation of phthalates in aquatic environments by non-target analysis

Oxidative degradation of most recalcitrant organics in the wastewater by exciting the oxidative potential and high efficacy of economic and environmental compatible oxidants is currently an extensively studied field of research. In this study, an efficient phthalate esters (PAEs) degradation method utilizing dual oxidants persulfate (PS) and hydrogen peroxide in the presence of ferrous ions was developed with high removal efficiency, small oxidant dosage and wide pH range. Compared with the degradation efficiency of single systems including Fe2+/ H2O2 (40 %), PS (24 %) and Fe2+/PS (49 %) for dimethyl phthalate (DMP) degradation, the combining PS and H2O2 activated by Fe2+ is more effective, with the removal efficiency of 95 %. The synergistic effect of PS and H2O2 in the Fe2+-containing system on PAEs degradation was reflected by the degradation products determined by non-target analysis of various oxidation processes. The results showed that the degradation of DMP in two single oxidant systems was dominated by aromatic compounds via dealkylation, hydroxyl addition and decarboxylation, while DMP in the PS/H2O2/FeSO4 system was mainly deeply oxidized to aliphatic molecules through further dearomatization, which was vulnerable for the mineralization of DMP to CO2 and H2O. In addition, the EPR technique combined with DMPO captured SO4•− and •OH signals in the presence of the same Fe2+ and oxidant dosage, revealing that a higher intensity of ·OH and SO4•− generated in the combined oxidative process resulted in a high removal of DMP. This work lays the groundwork for recalcitrant organics removal to apply synergistic activation mode in the AOPs system.

Adsorption Effect and Adsorption Mechanism of High Content Zeolite Ceramsite on Asphalt VOCs.

In order to meet the requirements of industrial-scale fixed beds and develop an excellent adsorbent for asphalt VOCs. Zeolite ceramsite containing binder was prepared and successfully applied to the inhibition of asphalt VOCs. The results showed that prepared zeolite ceramsite possessed a high degree of crystallinity, and its main crystal phase is zeolite. The micropores with a pore size of 0.88 nm dominated the pore size distribution of the material. The adsorption experiment of asphalt VOCs showed a lower VOCs adsorption effect of 8.72% at a small dosage of 5%, while at a large dosage of 50%, the adsorption effect of VOCs exceeded 45%. This might be caused by the quite small external specific surface area, which occupied only 8.3% of the total specific surface area, and the low intraparticle diffusion coefficient due to the micropores. Meanwhile, the kinetics diameters of most aromatic hydrocarbons, which were comparable to the pore size of micropores, and the increase in the intraparticle diffusion resistance of aliphatic hydrocarbon molecules were the important factors in obtaining high adsorption of aromatic hydrocarbons in asphalt VOCs. Furthermore, the results indicated that the particulate adsorbent with a microporous structure should be mixed into the asphalt as a fine aggregate rather than an asphalt modifier for better asphalt VOCs adsorption effect.

Polyamines and Their Metabolism: From the Maintenance of Physiological Homeostasis to the Mediation of Disease.

The polyamines spermidine and spermine are positively charged aliphatic molecules. They are critical in the regulation of nucleic acid and protein structures, protein synthesis, protein and nucleic acid interactions, oxidative balance, and cell proliferation. Cellular polyamine levels are tightly controlled through their import, export, de novo synthesis, and catabolism. Enzymes and enzymatic cascades involved in polyamine metabolism have been well characterized. This knowledge has been used for the development of novel compounds for research and medical applications. Furthermore, studies have shown that disturbances in polyamine levels and their metabolic pathways, as a result of spontaneous mutations in patients, genetic engineering in mice or experimentally induced injuries in rodents, are associated with multiple maladaptive changes. The adverse effects of altered polyamine metabolism have also been demonstrated in in vitro models. These observations highlight the important role these molecules and their metabolism play in the maintenance of physiological normalcy and the mediation of injury. This review will attempt to cover the extensive and diverse knowledge of the biological role of polyamines and their metabolism in the maintenance of physiological homeostasis and the mediation of tissue injury.

Polyamine-Linked Cholesterol Incorporation in Rift Valley Fever Virus Particles Promotes Infectivity.

Viruses rely on an array of cellular metabolites to replicate and form progeny virions. One set of these molecules, polyamines, are small aliphatic molecules, which are abundant in most cells, that support virus infection; however, the precise roles of polyamines in virus infection remain incompletely understood. Recent work demonstrated that polyamine metabolism supports cellular cholesterol synthesis through translation of the key transcription factor SREBP2. Here, we show that the bunyavirus Rift Valley fever virus (RVFV) relies on both cholesterol and polyamines for virus infection. Depletion of cellular cholesterol or interruption of cholesterol trafficking negatively impacts RVFV infection. Cholesterol is incorporated into RVFV virions and mediates their infectivity in a polyamine-dependent manner; we find that the virus derived from polyamine-depleted cells lacks cholesterol within the virion membrane. Conversely, we find that virion-associated cholesterol is linked to the incorporation of spermidine within the virion. Our prior work demonstrated that polyamines facilitate pH-mediated fusion and genome release, which may be a consequence of cholesterol depletion within virions. Thus, our work highlights the metabolic connection between polyamines and cholesterol synthesis to impact bunyavirus infection. These data demonstrate the connectedness between cellular metabolic pathways and reveal potential avenues of therapeutic intervention.

Coupled variations of dissolved organic matter distribution and iron (oxyhydr)oxides transformation: Effects on the kinetics of uranium adsorption and desorption

The interactions between dissolved organic matter (DOM) molecules and minerals play significant roles in affecting the fate of carbon and contaminants in soil environment. However, the mechanisms controlling the variations of DOM molecules distribution during the transformation of Fe (oxyhydr)oxides, and the effects of these variations on contaminant behaviors are still largely unknown. In this study, the dynamic variations of DOM properties and distributions, and the kinetics of uranium adsorption on and desorption from Fe (oxyhydr)oxides during the transformation were investigated, employing a combination of Orbitrap mass spectrometry (MS), high-resolution transmission electron microscopy (HR-TEM), and kinetic experiments. Orbitrap MS results indicated that aliphatic molecules and phenolic and polyphenolic molecules with lower O/C values were preferentially released to solution. HR-TEM results indicated that the coprecipitated DOM molecules by ferrihydrite were mainly released to solution rather than sorbed on the newly formed lepidocrocite or goethite during the transformation. Furthermore, the stirred-flow experiment results suggested that soil DOM significantly reduced the adsorption of uranium on, and accelerated the release of uranium from Fe (oxyhydr)oxides, which was ascribed to the changed distribution of DOM molecules and the structure and composition of Fe (oxyhydr)oxides. Our results contribute to predicting contaminant behaviors in soils.

Roughness Volumes: An Improved RoughMob Concept for Predicting the Increase of Molecular Mobility upon Coarse-Graining.

The reduced number of degrees of freedom in a coarse-grained molecular model compared to its parent atomistic model not only makes it possible to simulate larger systems for longer time scales but also results in an artificial mobility increase. The RoughMob method [Meinel, M. K. and Müller-Plathe, F. J. Chem. Theory Comput. 2020, 16, 1411.] linked the acceleration factor of the dynamics to the loss of geometric information upon coarse-graining. Our hypothesis is that coarse-graining a multiatom molecule or group into a single spherical bead smooths the molecular surface and, thus, leads to reduced intermolecular friction. A key parameter is the molecular roughness difference, which is calculated via a numerical comparison of the molecular surfaces of both the atomistic and coarse-grained models. Augmenting the RoughMob method, we add the concept of the region where the roughness acts. This information is contained in four so-called roughness volumes. For 17 systems of homogeneous hydrocarbon fluids, simple one-bead coarse-grained models are derived by the structure-based iterative Boltzmann inversion. They include 13 different homogeneous aliphatic and aromatic molecules and two different mapping schemes. We present a simple way to correlate the roughness volumes to the acceleration factor. The resulting relation is able to a priori predict the acceleration factors for an extended size and shape range of hydrocarbon molecules, with different mapping schemes and different densities.

High-resolution mass spectrometry-based strategies for the target analysis and suspect screening of per- and polyfluoroalkyl substances in aqueous matrices

Per- and polyfluoroalkyl substances (PFASs) are a man-made diverse group of highly fluorinated aliphatic molecules, entailing risks to the ecosystems and human health. Herein, a streamlined, single-shot, HRMS-based analytical workflow for the quantitation and suspect screening of various PFAS was developed. Sample preparation was based on weak-anion exchange solid phase extraction, while instrumental analysis was performed by highly sensitive liquid chromatography Orbitrap–high-resolution mass spectrometry. The target method was optimized and validated for drinking water, surface water, and wastewater, while it was also modified to be efficient for leachates. Method performance was excellent in terms of linearity (R2 > 0.99), detection/quantification limits (reaching even at pg L−1 scale), recoveries (70–108 %, for most of the compounds), and precision (<20%). Isotopically labelled internal standards and matrix-matched calibration curves were used for quantification. The suspect analysis performed on a single-stage HRMS method operating in data-dependent ‘discovery’ mode. Thus, content-rich spectra were acquired and once combined with suspect screening features such as peak picking, feature alignment, and compound annotation enabled the putative annotation of the tested PFAS with high confidence. After evaluation, the presented fully elaborated workflow was applied to real samples to explore the putative annotation of the tested PFAS with high confidence for the first time in Greece for five different matrices, revealing maximum concentrations for PFOS 1.5 ng L−1 in tap water and 394.4 ng L−1 in effluent wastewater, and PFHxA 4284.8 ng L−1 in leachates.

Finding a Sensitive Surface-Enhanced Raman Spectroscopic Thermometer at the Nanoscale by Examining the Functional Groups.

Temperature variation at the nanoscale is pivotal for the thermodynamics and kinetics of small entities. Surface-enhanced Raman spectroscopy (SERS) is a promising technique for monitoring temperature variations at the nanoscale. A key but ambiguous topic is methods to design a sensitive SERS thermometer. Here, we elucidate that the type of chemical bond of molecular probes and the surface chemical bonding effect are crucial for maximizing the sensitivity of the SERS thermometer, as illustrated by the variable-temperature SERS measurements and quantum chemistry calculations for the frequency-temperature functions of a series of molecules. The sensitivity of the frequency-temperature function follows the sequence of triple bond > double bond > single bond, which is available for both aliphatic and aromatic molecules. The surface chemical bonding effect between the SERS substrate and molecular probe substantially increases the sensitivity of the frequency-temperature function. These results provide universally available guidelines for the rational design of a sensitive SERS thermometer by examining the functional groups of molecular probes.

Stocky1, a Novel Gene Involved in Maize Seedling Development and Cuticle Integrity.

The cuticle is the plant’s outermost layer that covers the surfaces of aerial parts. This structure is composed of a variety of aliphatic molecules and is well-known for its protective role against biotic and abiotic stresses in plants. Mutants with a permeable cuticle show developmental defects such as organ fusions and altered seed germination and viability. In this study, we identified a novel maize mutant, stocky1, with unique features: lethal at the seedling stage, and showing a severely dwarfed phenotype, due to a defective cuticle. For the first time, the mutant was tentatively mapped to chromosome 5, bin 5.04. The mutant phenotype investigated in this work has the potential to contribute to the elucidation of the role of the cuticle during plant development. The possibility of controlling this trait is of relevance in the context of climate change, as it may contribute to tolerance to abiotic stresses.

Trafficking Processes and Secretion Pathways Underlying the Formation of Plant Cuticles.

Cuticles are specialized cell wall structures that form at the surface of terrestrial plant organs. They are largely comprised lipidic compounds and are deposited in the apoplast, external to the polysaccharide-rich primary wall, creating a barrier to diffusion of water and solutes, as well as to environmental factors. The predominant cuticle component is cutin, a polyester that is assembled as a complex matrix, within and on the surface of which aliphatic and aromatic wax molecules accumulate, further modifying its properties. To reach the point of cuticle assembly the different acyl lipid-containing components are first exported from the cell across the plasma membrane and then traffic across the polysaccharide wall. The export of cutin precursors and waxes from the cell is known to involve plasma membrane-localized ATP-binding cassette (ABC) transporters; however, other secretion mechanisms may also contribute. Indeed, extracellular vesiculo-tubular structures have recently been reported in Arabidopsis thaliana (Arabidopsis) to be associated with the deposition of suberin, a polyester that is structurally closely related to cutin. Intriguingly, similar membranous structures have been observed in leaves and petals of Arabidopsis, although in lower numbers, but no close association with cutin formation has been identified. The possibility of multiple export mechanisms for cuticular components acting in parallel will be discussed, together with proposals for how cuticle precursors may traverse the polysaccharide cell wall before their assimilation into the cuticle macromolecular architecture.

Low-temperature ALD/MLD growth of alucone and zincone thin films from non-pyrophoric precursors.

The combined atomic/molecular layer deposition (ALD/MLD) technique is emerging as a state-of-the-art synthesis route for new metal-organic thin-film materials with a multitude of properties by combining those of the inorganic and the organic material. A major part of the studies so far reported have focused on aluminum or zinc alkyls, so-called alucone and zincone films, typically grown from trimethyl aluminum (TMA) or diethyl zinc (DEZ) as the metal-bearing precursor, and a simple aliphatic bi-functional alcohol molecule such as ethylene glycol (EG) as the organic precursor. However, these common precursors possess certain disadvantages: both TMA and DEZ are pyrophoric, DEZ being additionally thermally unstable, while EG has a strong tendency for various unideal reaction modes. Here we report novel ALD/MLD processes for alucone and zincone films based on non-pyrophoric bis-diisopropylamido-[3-(N,N-dimethylamino)propyl] aluminum(III) [Al(NiPr2)2(DMP)] and bis-3-(N,N-dimethylamino)propyl zinc(II) [Zn(DMP)2] precursors in combination with hydroquinone (HQ) as the organic precursor. We demonstrate that the [Al(NiPr2)2(DMP)] + HQ and [Zn(DMP)2] + HQ ALD/MLD processes work even at record low deposition temperatures (140 °C and 60 °C, respectively) yielding high-quality and relatively stable Al-HQ and Zn-HQ thin films with appreciably high growth rates (2.8 Å / cycle and 3.2 Å / cycle, respectively). Moreover, these ALD/MLD processes are compatible with the corresponding ALD processes, i.e. [Al(NiPr2)2(DMP)] + H2O and [Zn(DMP)2] + H2O, for the Al2O3 and ZnO films, thus opening up new horizons for the fabrication of novel metal-oxide : organic superlattice structures for e.g. flexible gas-barrier coatings or wearable thermoelectrics.

Influence of the Macromolecular architecture on the properties of biobased polyurethane tissue adhesives

Polyurethanes (PU) have recently emerged as promising biomaterials for tissue adhesive applications. Compared to other tissue adhesives, they offer substantial advantages such as the possibility to tailor adhesive strengths and curing times, for instance. All these properties are directly affected by the composition and final architecture. In this work, biobased two-components PU sealants were prepared, based on (i) an isocyanate-terminated prepolymer and (ii) a chain extender. Here, an exhaustive evaluation of the oligoester-diols and chain extenders influence on the sealants properties has been performed. In order to bring controlled variations on the final macromolecular architectures, three different prepolymers were prepared: two are based on poly(3-hydroxybutyrate) diol oligomers and another one on poly(lactic acid) diol oligomers, with a 50/50 isocyanate molar ratio of hexamethylene diisocyanate and biobased dimeryl diisocyanate. To study the chain extenders influence, five different aliphatic and linear bifunctional molecules were assessed, with varying length and functional groups reactivity. Ultimately, PUs obtained after the two-component systems curing were also fully characterized. They exhibited an overall good biocompatibility around 80%, with limited cytotoxicity. A wide range of physico-chemical and mechanical properties were also obtained, evidencing the importance of the macromolecular architecture on the systems final properties.

Antiviral activity of microalgae extracts against Mayaro virus

Mayaro fever, as it is called the disease caused by the Mayaro virus (MAYV), which presents symptoms similar to those of dengue and Zika fevers such as fever, rash, and arthralgia. Once the disease is detected, the treatment is still non-specific since up to the moment there is no therapy capable of curing. Historically, the most affected areas by Mayaro infections are bordered by the Amazon State, or located in the Amazon forest, North of Brazil. Moreover, researches have detected three confirmed cases in Rio de Janeiro, Southeastern Brazil. Many natural compounds from microalgae have attracted special attention owing to their broad spectrum of biological activities and they are called biopharmaceuticals. In this work, we performed a technological mapping aiming to prospect microalgae applied to Biopharmaceuticals. From this study, four strains of microalgae prospected were cultured and their antiviral activity was assayed in vitro against MAYV. The cell viability tests were performed on VERO cells (Verda Reno Cells) to evaluate the cytotoxicity of the extracts by CC50 notation and the inactivation capacity of the MAYV as measured by TCID50. The results showed that all the microalgae strains presented anti-Mayaro activity and the relative potency was superior to ribavirin, the commercial antiviral. Also, the preliminary characterization by TLC and NMR 1H analysis indicated in the extract composition terpenoid molecules and the majority presence of unsaturated aliphatic molecules.

Molecular evidence for the export of terrigenous organic matter to the north Gulf of Mexico by solid-state 13C NMR and Fourier transform ion cyclotron resonance mass spectrometry of humic acids

Sediment samples along a transect extending from the Mississippi River Birdsfoot Delta to the Mississippi Canyon on the Louisiana continental shelf were examined, by advanced analytical techniques, electrospray ionization coupled to a 12T Fourier transform ion cyclotron resonance mass spectrometer (ESI-FTICR-MS) and quantitative solid-state multiple cross polarization magic angle spinning (multi-CPMAS) 13C NMR, in an effort to understand the source and export of terrigenous organic matter to the Gulf of Mexico. Both NMR and mass spectral data indicate that condensed aromatics (CA) and carboxyl-containing aliphatic molecules (CCAM) are present at the mouth of the river, reflective of high contributions from terrigenous soil-like organic matter. Mass spectral peak magnitudes of CA diminish by 15%, with increasing distance offshore, and represent 30% of integrated NMR peak areas. In contrast, mass spectral and NMR CCAM peaks increase by 7 and 13%, respectively. These trends in humic acid extracts, provide novel molecular evidence of terrigenous organic matter deposition in offshore sediments.

A simple and ultrasensitive metal-organic framework-based aptasensor for fluorescence detection of ethanolamine

In this research, a facile fluorescence aptasensor was designed for the ultrasensitive determination of ethanolamine (ETA) as an aliphatic amino alcohol molecule with harmful side effects for human health. Zeolitic imidazolate framework-8 (ZIF-8) as an efficient metal-organic framework was applied to quench the fluorescence emission of the FAM-labeled ETA aptamer. The presence of ETA could recover the fluorescence response under the optimal experimental conditions. ETA could be sensitively detected by the designed aptasensor in the linear concentration range of 0.1 nM-20 µM with the detection limit of 14.38 pM. The designed aptasensor was utilized to determine ETA in milk and serum samples with the detection limits of 17.86 and 15.21 pM, respectively. The aptasensor with the remarkable features of high sensitivity, simplicity and feasibility holds the supreme potential to construct a low-cost portable sensing method for food safety control, human diagnostics, and environmental monitoring with coupling to the microfluidic paper-based devices.

Composition of organics on asteroid (101955) Bennu

Context. The Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission detected an infrared absorption at 3.4 μm on near-Earth asteroid (101955) Bennu. This absorption is indicative of carbon species, including organics, on the surface. Aims. We aim to describe the composition of the organic matter on Bennu by investigating the spectral features in detail. Methods. We use a curated set of spectra acquired by the OSIRIS-REx Visible and InfraRed Spectrometer that have features near 3.4 μm (3.2 to 3.6 μm) attributed to organics. We assess the shapes and strengths of these absorptions in the context of laboratory spectra of extraterrestrial organics and analogs. Results. We find spectral evidence of aromatic and aliphatic CH bonds. The absorptions are broadly consistent in shape and depth with those associated with insoluble organic matter in meteorites. Given the thermal and space weathering environments on Bennu, it is likely that the organics have not been exposed for long enough to substantially decrease the H/C and destroy all aliphatic molecules.