Hasil untuk "Analytical chemistry"

M. Erickson

Christopher G. Parker, Matthew R. Pratt

Despite advances in genetic and proteomic techniques, a complete portrait of the proteome and its complement of dynamic interactions and modifications remains a lofty, and as of yet, unrealized, objective. Specifically, traditional biological and analytical approaches have not been able to address key questions relating to the interactions of proteins with small molecules, including drugs, drug candidates, metabolites, or protein post-translational modifications (PTMs). Fortunately, chemists have bridged this experimental gap through the creation of bioorthogonal reactions. These reactions allow for the incorporation of chemical groups with highly selective reactivity into small molecules or protein modifications without perturbing their biological function, enabling the selective installation of an analysis tag for downstream investigations. The introduction of chemical strategies to parse and enrich subsets of the "functional" proteome has empowered mass spectrometry (MS)-based methods to delve more deeply and precisely into the biochemical state of cells and its perturbations by small molecules. In this Primer, we discuss how one of the most versatile bioorthogonal reactions, "click chemistry", has been exploited to overcome limitations of biological approaches to enable the selective marking and functional investigation of critical protein-small-molecule interactions and PTMs in native biological environments.

Hanghui Liu, P. Dasgupta

Davide Castaldo, Markus Reiher

Chemistry and materials science are widely regarded as potential killer application fields for quantum hardware. While the dream of unlocking unprecedented simulation capabilities remains compelling, quantum algorithm development must adapt to the evolving constraints of the emerging quantum hardware in order to accomplish any advantage for the computational chemistry practice. At the same time, the continuous advancement of classical wavefunction-theory methods narrows the window for a broad quantum advantage. Here, we explore potential benefits of quantum computation from the broader perspective of utility-scale applications. We argue that quantum algorithms need not only enable accurate calculations for a few challenging, that is strongly correlated, molecular structures, that might be hard to describe with traditional methods. Instead, they must also support the practical integration of quantum-accelerated computations into high-throughput pipelines for routine calculations on arbitrary molecules, ultimately delivering a tangible value to society.

Rugaved R. Gudadhe, Gaurav R. Sawarkar, Amol M. Deshpande

Hair plays a significant role in personality and aesthetics, with androgenetic alopecia affecting up to 80% of males. This case study evaluates the efficacy of palliative treatment and Viddhakarma (Puncture Therapy in Ayurveda) in managing androgenetic alopecia (Khalitya). A 37-year-old man presented with hair loss and a mild burning sensation on the scalp for six to seven years, primarily in the vertex and frontal regions. Treatment included Viddhakarma, Nilibhringadi Taila application (Shiroabhyanga), and palliative medications for four months, with weekly monitoring. New hair roots appeared within two weeks, existing hair improved in quality, and warmth sensation normalized after a month. Significant regrowth was observed without adverse effects, highlighting the effectiveness of personalized Ayurvedic management for androgenetic alopecia.

Deepa D. Nakmode, Souha H. Youssef, Soumyajit Das et al.

Abstract The developed method for simultaneous detection of levodopa and carbidopa was able to separate the peaks of the drug and sodium bisulfite in the in-vitro release samples and stability samples. Levodopa (LD), a pro-drug of dopamine, is used as the gold standard treatment for Parkinson’s disease. It is usually prescribed with carbidopa (CD) to prevent the conversion of levodopa to dopamine peripherally, thus reducing undesirable side effects. Both drugs are unstable at pH 7.4 beyond 24 h due to their oxidation, therefore 0.2% sodium bisulfite is added to the formulation as an antioxidant. The separation was performed by gradient elution using the Luna-C18 column (250 × 4.6 mm, 5 µm) at a flow rate of 1 ml/min. The mobile phase was composed of mobile phase A 30 mM potassium phosphate and acetonitrile (95:5, v/v) with 35 mM tetrabutylammonium hydrogen sulphate and mobile phase B containing 30 mM potassium phosphate and acetonitrile (50:50 v/v). Drug peaks were detected at 280 nm with retention times of 3.05 ± 0.001 min for LD and 3.64 ± 0.001 min for CD. The validation of the method according to US FDA guidelines and results were found to be within acceptable limits. The method was linear from 10–100 µg/ml (r2 = 0.999) and 10–100 µg/ml (r2 = 0.999) for LD and CD, respectively. The developed method was applied to studying the drug release from in-situ gel. The environmental impact of the developed method was evaluated using various greenness assessment tools. Graphical abstract

Siddharth M. Narayanan, James D. Braza, Ryan-Rhys Griffiths et al.

Reasoning models are large language models that emit a long chain-of-thought before answering, providing both higher accuracy and explicit reasoning for their response. A major question has been whether language model reasoning generalizes beyond mathematics, programming, and logic, where most previous work has focused. We demonstrate that reasoning models can be post-trained for chemistry without additional domain pretraining, and require substantially less data compared to contemporary domain-specific models. We report ether0, a 24B parameter LLM (based on Mistral-Small-24B) that can reason in natural language and respond with chemical structures. This reasoning model was trained with reinforcement learning on 640,730 experimentally-grounded chemistry problems across 375 tasks ranging from synthesizability, to blood-brain barrier permeability, to human receptor activity, to scent. Our model exceeds general-purpose chemistry models, frontier models, and human experts on molecular design tasks. It is also more data efficient relative to specialized models. We anticipate that this method can be applied to train data-efficient language models specialized for tasks across a wide variety of scientific domains.

Shantanu Mishra, Valentina Malave, Rasmus Svensson et al.

Skeletal editing of cyclic molecules has garnered considerable attention in the context of drug discovery and green chemistry, with notable examples in solution-phase synthesis. Here, we extend the scope of skeletal editing to the single-molecule scale. We demonstrate tip-induced oxygen deletion and ring contraction of an oxygen-containing seven-membered ring on bilayer NaCl films to generate molecules containing the perylene skeleton. The products were identified and characterized by atomic force and scanning tunneling microscopies, which provided access to bond-resolved molecular structures and orbital densities. Insights into the reaction mechanisms were obtained by density functional theory calculations. Our work expands the toolbox of tip-induced chemistry for single-molecule synthesis.

Vidhya Rekha Umapathy, Bhuminathan Swamikannu, Prabhu Manickam Natarajan et al.

Background: Oral cancer is the sixth most common cancer occurring anywhere in the globe. Cancers of the mouth are caused by tobacco and alcohol overuse, and also between pre-malignancy and full-fledged malignancy. In order to avoid the onset of illness, proper cleanliness of the mouth is important. Objective: In this study we aimed to identify the potential inhibitor for Aurora kinase B as a potential therapeutic target for oral cancer from the phytocompounds from Ocimum sanctum. Methodology: Compounds from Ocimum sanctum were screened against Aurora kinase B using a structure-based virtual screening approach using Pyrx software. Based on the scoring parameters best compounds were chosen to analysis the interaction by using Discovery studio visualizer. Results: Four compounds—pedunculin, nevadensin, chrysoeriol, and genistein were selected as the most promising leads based on the scoring parameter. Conclusion: These chemicals could be potential therapeutic candidates that need to be investigated further in the laboratory.

M Gunasekaran, Sonali Sharma, Kolla Lakshmiprasanna et al.

Nanotechnology is revolutionizing prosthodontics by enhancing the aesthetics, durability, and functionality of dental restorations. Nanomaterials can mimic the natural appearance of teeth with unprecedented precision, resulting in lifelike and visually appealing prosthetics. Their superior strength and wear resistance extend the longevity of restorations, reducing the need for replacements and lowering costs. Beyond aesthetics and durability, nanomaterials can be engineered with unique properties, such as antibacterial effects and the ability to deliver therapeutic agents, improving oral health and patient comfort. This review explores the current applications and future opportunities of nanotechnology in prosthodontics, offering valuable insights for dental professionals and researchers interested in its transformative potential.

Miriam Hernández-Jiménez, Isabel Revilla, Ana M. Vivar-Quintana et al.

Iberian ham is a highly appreciated product and according to Spanish legislation different labels identify different products depending on the genetic purity. Consequently, “100% Iberian” ham from purebred Iberian animals is more expensive than “Iberian” ham from Iberian x Duroc crosses. The hypothesis of this study was that to avoid labelling fraud it is possible to distinguish the breed (Iberian or Iberian x Duroc) of acorn-fed pigs of Iberian ham without any prior preparation of the sample by using spectroscopy that is a rapid and reliable technology. Moreover, portable devices which can be used in situ could provide similar results to those of benchtop equipment. Therefore, the spectra of the 60 samples (24 samples of 100% Iberian ham and 36 samples of Iberian x Duroc crossbreed ham) were recorded only for the fat, only for the muscle, or for the whole slice with two benchtop near-infrared (NIR) spectrometers (Büchi NIRFlex N-500 and Foss NIRSystem 5000) and five portable spectrometers including four portable NIR devices (VIAVI MicroNIR 1700 ES, TellSpec Enterprise Sensor, Thermo Fischer Scientific microPHAZIR, and Consumer Physics SCiO Sensor), and one RAMAN device (BRAVO handheld). The results showed that, in general, the whole slice recording produced the best results for classification purposes. The SCiO device showed the highest percentages of correctly classified samples (97% in calibration and 92% in validation) followed by TellSpec (100% and 81%). The SCiO sensor also showed the highest percentages of success when the analyses were performed only on lean meat (97% in calibration and 83% in validation) followed by microPHAZIR (84% and 81%), while in the case of the fat tissue. Raman technology showed the best discrimination capacity (96% and 78%) followed by microPHAZIR (89% and 81%). Therefore, spectroscopy has proved to be a suitable technology for discriminating ham samples according to breed purity; portable devices have been shown to give even better results than benchtop spectrometers.

Dwaipee De, Sreerupa Sarkar, Himashree Chhetri et al.

Abstract Meteorological and edaphic factors significantly affect the first flush metabolite composition of Darjeeling tea, impacting flavor, nutrition, and customer preferences. The Camellia sinensis var. sinensis grown in the Darjeeling hills was sampled at different stages of processing. 75 metabolites were identified using a GC/MS-based metabolomic and chemometric technique. The study aimed to pinpoint quality markers and create a database for Darjeeling tea authenticity, India’s first geographical indication product. Principal component analysis and partial least squares discriminant analysis revealed changes in tea metabolites during processing, while the chemometric study demonstrated variations in key compounds. Antioxidant activity exhibited significant variations among the samples with final processed showing highest antioxidant potential. The concentration of amino acids increased significantly (p < 0.05) from fresh tea leaves to the final processed product. Conversely, the content of organic acids, inorganic acids, and fatty acids was observed to decrease. Additionally, caffeic acids, epicatechin, epigallocatechin, chlorogenic acid, 3, 4-dihydroxybenzoic acid, and 4-hydroxycinnamic acid increased in concentration, while catechin, (-)-epicatechin, gallic acid, pyrogallol, quinic acid, shikimic acid, and arbutin decreased significantly in concentration in the final processed tea. Meteorological parameters were documented during the study period, showing variation in the levels of PM2.5, PM10, O3, NO2, and SO2. The findings of this study offer insightful information on the variables influencing Darjeeling tea metabolite composition, which tea producers and processors can use to raise the standard and authenticity of this beverage. Graphical abstract

Abisha Christy Christudoss, Rita Kundu, Christian O. Dimkpa et al.

The use of disposable face masks (DFMs) increased during the COVID-19 pandemic and has become a threat to the environment due to the release of microplastics (MPs). Although many reports have characterized and explored the release of MPs from DFMs and their effects in aquatic ecosystems, there is a lack of investigation into the effects in terrestrial plants. This report aims to fill this research gap by characterizing whole mask leachates (WMLs) collected at different time points and examining their toxicity on Allium cepa, a terrestrial model plant. Various analytical techniques including FE-SEM, FT-IR, and Raman spectroscopy were used to identify MPs in WMLs. The MPs are composed of polypropylene mostly and the concentration of smaller-sized MPs increased with leachate release time. The WMLs showed a MP concentration-dependent cytogenotoxic effect (72 %, 50 %, and 31 %, on 1, 5, and 11-day WMLs, respectively) on A. cepa root cells due to elevated oxidative stress (19 %, 45 %, and 70 %, on 1, 5, and 11-day WMLs, respectively). Heavy metal content of the WMLs was negligible and, thus, not a significant contributor to toxicity in the plant. Overall, this report highlights the fate of DFMs in the environment and their biological impacts in a model plant.

Tsutomu Miura

Ensuring accurate and precise measurements of analytes is crucial in gravimetric analysis but can be jeopardized by overlooking analyte in the filtrate, washing solutions, residue during analytical procedure, and weighing form of analyte. To address this issue, a stoichiometric approach for the purity determination of high-purity BeO was developed using gravimetric analysis. This method involved the systematic stoichiometric evaluation of the stepwise conversion of the different weighing forms of Be. The initial BeO sample underwent sequential conversion to the Be complex with N-benzoyl-N-phenyl hydroxylamine, BeO, and BeSO4; each was evaluated for stoichiometry via gravimetric analysis. The amounts of Be in the filtrate and washing solution, and their loss during sample preparation were measured using inductively coupled plasma-optical emission spectrometry (ICP-OES). Additionally, the sulfate content in the BeSO4 precipitate was determined by the gravimetric analysis of BaSO4 to validate the stoichiometry of the precipitate. The observed mass ratios of different Be weighing forms were compared with the theoretical values at each conversion step. The composition of the final converted BeSO4, i.e., the observed mass ratio of BaSO4/BeSO4, was comparable to the theoretical composition. The purity of the initial BeO sample was determined to be 100.03 % ± 0.17 % (k=2). The measured purity was successfully validated by comparing it with that of NIST SRM 3105a Be standard solution using ICP-OES.

Dimitra Kirgiafini, Argyris Serafim, Urania Menkissoglu-Spiroudi et al.

Nematodes have a negative impact on crop production and yield. The use of synthetic formulations to control plant parasitic nematodes carries both environmental and human health risks. As these agrochemicals are gradually being phased out, recent research has been focused on finding more environmentally friendly, plant-based alternatives. This study aims to investigate the effectiveness of botanicals, used alone or in artificial blends, in paralyzing <i>Meloidogyne incognita</i> second-stage juveniles (J2s) immersed in test solutions or exposed to vapors. We tested thymol, <i>trans</i>-anethole, and two lavender essential oils, referred to as LEOA and LEOB, which vary in their flower and stem compositions. We also employed in our study <i>Melia azedarach</i> aqueous extract (MWE), already proven to have considerable nematicidal activity. According to our findings, all treatments used individually exhibited considerable efficacy, even LEOA and LEOB first reported herein. In addition, all blends exhibited significant synergism, and the best-performing were <i>trans</i>-anethole/thymol, being synergic to paralyzing J2s for up to two days, and <i>trans</i>-anethole/LEOB as well as <i>trans</i>-anethole/MWE, provoking irreversible paralysis since the first day of J2 immersion in test solutions. Most importantly, the blend of <i>trans</i>-anethole with LEOA displayed the best effective synergism against <i>M. incognita</i> both for immersion and fumigation methods. Lastly, the chemical composition analysis displayed linalyl acetate and <i>β</i>-linalool as the major components of LEOA and <i>β</i>-linalool and eucalyptol as the major components of LEOB.

Robert P. Crease, Vladimir Shiltsev

This article, the third in a series about the Russian scientist Mikhail Lomonosov (1711-1765), covers the first decade of his research at the St. Petersburg Academy of Sciences, from his return from an educational his trip abroad in 1741, to the mid-1750s. Lomonosov's major focus was on the establishment of the first Russian laboratory used to introduce modern experimental chemistry and physics methods both to original research and education. The lab supported studies of the physics of colors, chemistry and physics of glasses and training of the Academy students. This article describes how Lomonosov, first an Adjunct Professor and then as a young Professor, fought to create the chemistry lab, and then to establish a broad program of experiments and tests there. The construction of laboratories to be used not just for research but also education only became widespread in the early 19th century, but Lomonosov's laboratory had a significant impact on the early development of the Academy and on Russian science.

B. Sellergren

R. Meyers

S. Ferreira, W. N. D. dos Santos, C. Quintella et al.

Katerina P. Hilleke, Eva Zurek

An overview of the behavior of materials at high pressure is presented, starting from the effects on single atoms driving electronic transitions and changes in periodic trends. A range of high-pressure-induced phenomena in the solid state are then discussed building on the atomic changes, including bizarre electronic structures, electrides, compounds of noble gases, changes in elemental miscibility, and strange structural and bonding configurations. In the final section, the field of high pressure superconductivity is discussed, as high pressure phases have generated immense study and excitement as some of their critical superconducting temperatures approach room temperature.