Improving assay feasibility and biocompatibility of 3D cyclic olefin copolymer microwells by superhydrophilic modification via ultrasonic spray deposition of polyvinyl alcohol.

Sample partitioning is a crucial step towards digitization of biological assays on polymer microfluidic platforms. However, effective liquid filling into microwells and long-term hydrophilicity remain a challenge in polymeric microfluidic devices, impeding the applicability in diagnostic and cell culture studies. To overcome this, a method to produce permanent superhydrophilic 3-dimensional microwells using cyclic olefin copolymer (COC) microfluidic chips is presented. The COC substrate is oxidized using UV treatment followed by ultrasonic spray coating of polyvinyl alcohol solution, offering uniform and long-term coating of high-aspect ratio microfeatures. The coated COC surfaces are UV-cured before bonding with a hydrophobic pressure-sensitive adhesive to drive selective filling into the wells. The surface hydrophilicity achieved using this method remains unchanged (water contact angle of 9°) for up to 6 months and the modified surface is characterized for physical (contact angle & surface energy, morphology, integrity of microfeatures and roughness), chemical composition (FTIR, Raman spectroscopy) and coating stability (pH, temperature, time). To establish the feasibility of the modified surface in biological applications, PVA-coated COC microfluidic chips are tested for DNA sensing (digital LAMP detection of CMV), and biocompatibility through protein adsorption and cell culture studies (cell adhesion, viability, and metabolic activity). Kidney and breast cells remained viable for the duration of testing (7 days) on this modified surface, and the coating did not affect the protein content, morphology or quality of the cultured cells. The ultrasonic spray coated system, coating with 0.25 % PVA for 15 cycles with 0.12 A current after UV oxidation, increased the surface energy of the COC (naturally hydrophobic) from 22.04 to 112.89 mJ/m2 and improved the filling efficiency from 40 % (native untreated COC) to 94 % in the microwells without interfering with the biocompatibility of the surface, proving to be an efficient, high-throughput and scalable method of microfluidic surface treatment for diagnostic and cell growth applications.

Integration of acoustic micromixing with cyclic olefin copolymer microfluidics for enhanced lab-on-a-chip applications in nanoscale liposome synthesis.

The integration of acoustic wave micromixing with microfluidic systems holds great potential for applications in biomedicine and lab-on-a-chip technologies. Polymers such as cyclic olefin copolymer (COC) are increasingly utilized in microfluidic applications due to its unique properties, low cost, and versatile fabrication methods, and incorporating them into acoustofluidics significantly expands their potential applications. In this work, for the first time, we demonstrated the integration of polymer microfluidics with acoustic micromixing utilizing oscillating sharp edge structures to homogenize flowing fluids. The sharp edge mixing platform was entirely composed of COC fabricated in a COC-hydrocarbon solvent swelling based microfabrication process. As an electrical signal is applied to a piezoelectric transducer bonded to the micromixer, the sharp edges start to oscillate generating vortices at its tip, mixing the fluids. A 2D numerical model was implemented to determine the optimum microchannel dimensions for experimental mixing assessment. The system was shown to successfully mix fluids at flow rates up to 150µl h-1and has a modest effect even at the highest tested flow rate of 600µl h-1. The utility of the fabricated sharp edge micromixer was demonstrated by the synthesis of nanoscale liposomes.

Cyclic olefin copolymer (COC) as a promising biomaterial for affecting bacterial colonization: investigation on Vibrio campbellii.

Cyclic olefin copolymer (COC) has emerged as an interesting biocompatible material for Organ-on-a-Chip (OoC) devices monitoring growth, viability, and metabolism of cells. Despite ISO 10993 approval, systematic investigation of bacteria grown onto COC is a still not documented issue. This study discusses biofilm formations of the canonical wild type BB120 Vibrio campbellii strain on a native COC substrate and addresses the impact of the physico-chemical properties of COC compared to conventional hydroxyapatite (HA) and poly(dimethylsiloxane) (PDMS) surfaces. An interdisciplinary approach combining bacterial colony counting, light microscopy imaging and advanced digital image processing remarks interesting results. First, COC can reduce biomass adhesion with respect to common biopolymers, that is suitable for tuning biofilm formations in the biological and medical areas. Second, remarkably different biofilm morphology (dendritic complex patterns only in the case of COC) was observed among the examined substrates. Third, the observed biofilm morphogenesis was related to the interaction of COC with the conditioning layer of the planktonic biological medium. Fourth, Level Co-occurrence Matrix (CGLM)-based analysis enabled quantitative assessment of the biomass textural fractal development under different coverage conditions. All of this is of key practical relevance in searching innovative biocompatible materials for pharmaceutical, implantable and medical products.

Synthesis and Inhibitor Effect Novel Alkoxymethyl Derivatives of Dihetero Cycloalkanes on Carbonic Anhydrase and Acetylcholinesterase.

1,3-Diheterocycloalkanes derivatives are important starting materials in fine organic synthesis. These compounds can be widely used in various fields such as industry, medicine, biotechnology and chemical technology. The paper is focused on synthesis and study of alkoxymethyl derivatives of diheterocycloalkanes (M1-M15) and inhibition effect on carbonic anhydrase and acetylcholinesterase. The structures of compounds were confirmed by 1H and 13C NMR spectroscopy. Also, in this study alkoxymethyl derivatives of diheterocycloalkanes were assessed for their influence on various metabolic enzymes, including acetylcholinesterase (AChE) and human carbonic anhydrase isoenzymes (hCA I and hCA II). The results demonstrated that all these compounds exhibited potent inhibitory effects on all the target enzymes, surpassing the standard inhibitors, as evidenced by their IC50 and Ki values. The Ki values for the compounds concerning AChE, hCA I, and hCA II enzymes were in the ranges of 1.02±0.17-8.38±1.02, 15.30±3.15-58.14±5.17 and 24.05±3.70-312.94±27.24 nM, respectively.

Transannular C-H functionalization of cycloalkane carboxylic acids.

Cyclic organic molecules are common among natural products and pharmaceuticals1,2. In fact, the overwhelming majority of small-molecule pharmaceuticals contain at least one ring system, as they provide control over molecular shape, often increasing oral bioavailability while providing enhanced control over the activity, specificity and physical properties of drug candidates3-5. Consequently, new methods for the direct site and diastereoselective synthesis of functionalized carbocycles are highly desirable. In principle, molecular editing by C-H activation offers an ideal route to these compounds. However, the site-selective C-H functionalization of cycloalkanes remains challenging because of the strain encountered in transannular C-H palladation. Here we report that two classes of ligands-quinuclidine-pyridones (L1, L2) and sulfonamide-pyridones (L3)-enable transannular γ-methylene C-H arylation of small- to medium-sized cycloalkane carboxylic acids, with ring sizes ranging from cyclobutane to cyclooctane. Excellent γ-regioselectivity was observed in the presence of multiple ß-C-H bonds. This advance marks a major step towards achieving molecular editing of saturated carbocycles: a class of scaffolds that are important in synthetic and medicinal chemistry3-5. The utility of this protocol is demonstrated by two-step formal syntheses of a series of patented biologically active small molecules, prior syntheses of which required up to 11 steps6.

GTL synthetic paraffin oil shows low liver and tissue retention compared to mineral oil.

Oral exposure to mineral oil may result in a narrow fraction of mineral oil saturated hydrocarbon (MOSH) being retained in tissues. Excess of MOSH hepatic retention may lead to the formation of lipogranuloma caused by predominantly multiring cycloalkanes (naphthenics) in a critical range of C25-C35. Although hepatic lipogranuloma is of low pathological concern, MOSH tissue deposition could be minimized by using an oil of similar quality but devoid of naphthenic structures to decrease hepatic retention. Synthetic Gas to liquid (GTL) oils offer an alternative to petroleum derived mineral oils, because they do not contain naphthenic structures. To demonstrate this point, SD rats were fed either GTL oil (99% iso-alkanes) or naphthenic mineral oil (84% cycloalkanes) at 200 mg/kg bw/day for 90 or 134 days with a recovery group. Liver, fat and mesenteric lymph nodes were analyzed for alkane sub-type levels using Online-HPLC-GC-FID and GCxGC-TOF-MS. Results indicate that at equal external dose, GTL hydrocarbons result in lower tissue levels and more rapid excretion than MOSH. GTL retained hepatic fractions were also qualitatively different than MOSH constituents. Because chemical composition differences, GTL oil show low absorption and tissue retention potential and thus an advantageous alternative to conventional mineral oil.

Cycloalkane-modified amphiphilic polymers provide direct extraction of membrane proteins for CryoEM analysis.

Membrane proteins are essential for cellular growth, signalling and homeostasis, making up a large proportion of therapeutic targets. However, the necessity for a solubilising agent to extract them from the membrane creates challenges in their structural and functional study. Although amphipols have been very effective for single-particle electron cryo-microscopy (cryoEM) and mass spectrometry, they rely on initial detergent extraction before exchange into the amphipol environment. Therefore, circumventing this pre-requirement would be a big advantage. Here we use an alternative type of amphipol: a cycloalkane-modified amphiphile polymer (CyclAPol) to extract Escherichia coli AcrB directly from the membrane and demonstrate that the protein can be isolated in a one-step purification with the resultant cryoEM structure achieving 3.2 Å resolution. Together this work shows that cycloalkane amphipols provide a powerful approach for the study of membrane proteins, allowing native extraction and high-resolution structure determination by cryoEM.

Intermolecular Diels-Alder Cycloadditions of Furfural-Based Chemicals from Renewable Resources: A Focus on the Regio- and Diastereoselectivity in the Reaction with Alkenes.

A recent strong trend toward green and sustainable chemistry has promoted the intensive use of renewable carbon sources for the production of polymers, biofuels, chemicals, monomers and other valuable products. The Diels-Alder reaction is of great importance in the chemistry of renewable resources and provides an atom-economic pathway for fine chemical synthesis and for the production of materials. The biobased furans furfural and 5-(hydroxymethyl)furfural, which can be easily obtained from the carbohydrate part of plant biomass, were recognized as "platform chemicals" that will help to replace the existing oil-based refining to biorefining. Diels-Alder cycloaddition of furanic dienes with various dienophiles represents the ideal example of a "green" process characterized by a 100% atom economy and a reasonable E-factor. In this review, we first summarize the literature data on the regio- and diastereoselectivity of intermolecular Diels-Alder reactions of furfural derivatives with alkenes with the aim of establishing the current progress in the efficient production of practically important low-molecular-weight products. The information provided here will be useful and relevant to scientists in many fields, including medical and pharmaceutical research, polymer development and materials science.

Application of Polyamines and Amino Acid Derivatives Based on 2-Azabicycloalkane Backbone in Enantioselective Aldol Reaction.

Carbon-carbon bond forming reactions, such as aldol reaction and condensation, belong to extremely desired transformations as manifested by >25,000 entries in SciFinder. Their stereoselective variant requires the use of an appropriate catalyst with a strictly defined structure. Hence, chiral 2-azabicycloalkane-based catalysts were designed, synthesized and tested in a stereoselective aldol reaction between cyclic/acyclic ketone and p-nitrobenzaldehyde both in organic and aqueous media. Among catalysts containing a chiral bicyclic backbone, amide based on 2-azabicyclo[3.2.1]octane and pyrrolidine units showed the best catalytic activity and afforded aldol product in excellent chemical yields (up to 95%) and good diastereo- and enantioselectivity (dr 22:78, ee up to 63%).

Antitumor Profile of Carbon-Bridged Steroids (CBS) and Triterpenoids.

This review focuses on the rare group of carbon-bridged steroids (CBS) and triterpenoids found in various natural sources such as green, yellow-green, and red algae, marine sponges, soft corals, ascidians, starfish, and other marine invertebrates. In addition, this group of rare lipids is found in amoebas, fungi, fungal endophytes, and plants. For convenience, the presented CBS and triterpenoids are divided into four groups, which include: (a) CBS and triterpenoids containing a cyclopropane group; (b) CBS and triterpenoids with cyclopropane ring in the side chain; (c) CBS and triterpenoids containing a cyclobutane group; (d) CBS and triterpenoids containing cyclopentane, cyclohexane or cycloheptane moieties. For the comparative characterization of the antitumor profile, we have added several semi- and synthetic CBS and triterpenoids, with various additional rings, to identify possible promising sources for pharmacologists and the pharmaceutical industry. About 300 CBS and triterpenoids are presented in this review, which demonstrate a wide range of biological activities, but the most pronounced antitumor profile. The review summarizes biological activities both determined experimentally and estimated using the well-known PASS software. According to the data obtained, two-thirds of CBS and triterpenoids show moderate activity levels with a confidence level of 70 to 90%; however, one third of these lipids demonstrate strong antitumor activity with a confidence level exceeding 90%. Several CBS and triterpenoids, from different lipid groups, demonstrate selective action on different types of tumor cells such as renal cancer, sarcoma, pancreatic cancer, prostate cancer, lymphocytic leukemia, myeloid leukemia, liver cancer, and genitourinary cancer with varying degrees of confidence. In addition, the review presents graphical images of the antitumor profile of both individual CBS and triterpenoids groups and individual compounds.

p-Trifluoromethyl- and p-pentafluorothio-substituted curcuminoids of the 2,6-di[(E)-benzylidene)]cycloalkanone type: Syntheses and activities against Leishmania major and Toxoplasma gondii parasites.

A series of the title curcuminoids with structural variance in the heteroatom of the cycloalkanone and the p-substituents of the phenyl rings were tested for their activities against Leishmania major and Toxoplasma gondii parasites. The majority of them showed high activities against both parasite forms with EC50 values in the sub-micromolar concentration range. Bis(p-pentafluorothio)-substituted 3,5-di[(E)-benzylidene]piperidin-4-one 1b was not just noticeable antiparasitic, but also exhibited a considerable selectivity for L. major promastigotes over normal Vero cells. While derivatives differing only in the p-phenyl substituents being CF3 or SF5 showed similar antiparasitic activities, the cyclic ketone hub was more decisive both for the anti-parasitic activities and the selectivities for the parasites vs. normal cells. QSAR calculations confirmed the observed structure-activity relations and suggested structural variations for a further improvement of the antiparasitic activity. Docking studies based on DFT calculations revealed L. major pteridine reductase 1 as a likely molecular target protein of the title compounds.

Novel chiral naphthalimide-cycloalkanediamine conjugates: Design, synthesis and antitumor activity.

A novel series of enantiopure naphthalimide-cycloalkanediamine conjugates were designed, synthetized and evaluated for in vitro cytotoxicity against human colon adenocarcinoma (LoVo), human lung adenocarcinoma (A549), human cervical carcinoma (Hela) and human promyelocytic leukemia cell lines (HL-60). The cytotoxicity of the compounds was highly dependent on size and relative stereochemistry of the cycloalkyl ring as well as length of the spacer. By contrast, any kind of enantioselection was observed for each pair of enantiomers. Flow cytometric analysis indicated that compounds 22 and 23 could effectively induce G2/M arrest in the four previous cell lines despite a mild apoptotic effect.

7-Amine-spiro[chromeno[4,3-b]quinoline-6,1'-cycloalkanes]: Synthesis and cholinesterase inhibitory activity of structurally modified tacrines.

Five new examples of 9,10-chloro(bromo)-7-amine-spiro[chromeno[4,3-b]quinoline-6,1'-cycloalkanes] - in which cycloalkanes = cyclopentane, cyclohexane, and cycloheptane - were synthesized at yields of 42-56%, using a sequential one-pot two-step cyclocondensation reaction of three different scaffolds of 2-aminobenzonitriles and the respective spiro[chroman-2,1'-cycloalkan]-4-ones, and using AlCl3 as the catalyst in a solvent-free method. Subsequently, the five new spirochromeno-quinolines and nine quinolines previously published by us (14 modified tacrine scaffolds) were subjected to AChE and BChE inhibitory activity evaluation. The molecule containing a spirocyclopentane derivative had the highest AChE and BChE inhibitory activity (IC50 = 3.60 and 4.40 µM, respectively), and in general, the non-halogenated compounds were better inhibitors of AChE and BChE than the halogenated molecules. However, the inhibitory potency of compounds 3a-n was weaker than that of tacrine. By molecular docking simulations, it was found that the size of the spirocarbocyclic moieties is inversely proportional to the inhibitory activity of the cholinesterases, probably because an increase in the size of the spirocyclic component sterically hindered the interaction of tacrine derivatives with the active site of tested cholinesterases. The findings obtained here may help in the design and development of new anticholinesterase drugs.

Mechanisms and Substituent Effects of Metal-Free Bioorthogonal Reactions.

Reactions that occur under physiological conditions find diverse uses in the chemical and biological sciences. However, the limitations that biological systems place on chemical reactions restrict the number of such bioorthogonal reactions. A profound understanding of the mechanistic principles and structure-reactivity trends of these transformations is therefore critical to access new and improved versions of bioorthogonal chemistry. The present article reviews the mechanisms and substituent effects of some of the principal metal-free bioorthogonal reactions based on inverse-electron demand Diels-Alder reactions, 1,3-dipolar cycloadditions, and the Staudinger reaction. Mechanisms of modified versions that link these reactions to a dissociative step are further discussed. The presented summary is anticipated to aid the advancement of bioorthogonal chemistry.

Whole-cell biocatalysis using the Acidovorax sp. CHX100 Δ6HX for the production of ω-hydroxycarboxylic acids from cycloalkanes.

Omega hydroxycarboxylic acids (ω-HAs) possess two functional groups, a hydroxyl group and a carboxyl group, and are essential precursors for the production of biodegradable polyester polymers. In this work, an Acidovorax mutant was investigated as a whole-cell biocatalyst for the conversion of cycloalkanes to their respective ω-hydroxycarboxylic acids. This Acidovorax sp. strain CHX100 originated from a wastewater treatment plant and uses cyclohexane as the sole source of carbon and energy with excellent growth rates (0.199 h-1). The metabolic efficiency of Acidovorax CHX100 is based on a highly efficient enzyme cascade used for the mineralization of cyclohexane. A deletion of 6-hydroxyhexanoate dehydrogenase in the native cycloalkane pathway resulted in the Acidovorax sp. strain CHX100 Δ6HX mutant, which accumulated short ω-hydroxycarboxylic acids (C5 to C10) from cycloalkanes. This mutant transformed cyclopentane and cyclohexane (5 mM) to 5-hydroxypentanoic acid and 6-hydroxyhexanoic acid, respectively, with a molar conversion above 98% in 6 h. An elementary environmental and economical assessment based on E-factor and biocatalyst yield suggests the use of inexpensive electron donor and carbon sources, with subsequent efforts to minimize waste generation. Such an early-stage analysis highlights the main bottlenecks that need to be solved in developing a sustainable bioprocess.

Triple, Mutually Orthogonal Bioorthogonal Pairs through the Design of Electronically Activated Sulfamate-Containing Cycloalkynes.

Interest in mutually exclusive pairs of bioorthogonal labeling reagents continues to drive the design of new compounds that are capable of fast and predictable reactions. The ability to easily modify S-, N-, and O-containing cyclooctynes (SNO-OCTs) enables electronic tuning of various SNO-OCTs to influence their cycloaddition rates with Type I-III dipoles. As opposed to optimizations based on just one specific dipole class, the electrophilicity of the alkynes in SNO-OCTs can be manipulated to achieve divergent reactivities and furnish mutually orthogonal dual ligation systems. Significant reaction rate enhancements of a difluorinated SNO-OCT derivative, as compared to the parent scaffold, were noted, with the second-order rate constant in cycloadditions with diazoacetamides exceeding 5.13 M-1 s-1. Computational and experimental studies were employed to inform the design of triple ligation systems that encompass three orthogonal reactivities. Finally, polar SNO-OCTs are rapidly internalized by mammalian cells and remain functional in the cytosol for live-cell labeling, highlighting their potential for diverse in vitro and in vivo applications.

Carboalumination of Seven-Membered-Ring trans-Alkenes.

Seven-membered-ring trans-alkenes undergo rapid hydro- and carboalumination reactions in the absence of a catalyst with complete regio- and diastereoselectivity. Control experiments, including deuterium labeling, adding radical inhibitors, and using a radical clock, suggest that these reactions proceed by a concerted mechanism. The products of the reaction possess a new carbon-aluminum bond that can then undergo subsequent transformations, particularly oxidation, providing functionalized products as single stereoisomers.

Design, synthesis and biological evaluation of diamino substituted cyclobut-3-ene-1,2-dione derivatives for the treatment of drug-resistant tuberculosis.

Mycobacterium tuberculosis (Mtb) ATP synthase is an important target for treating drug-resistant infections and sterilizing the bacteria, spurring intensive efforts to develop new TB therapeutics based on this target. In this work, four novel series including furan-2(5H)-ketone (3, 4), maleimide (5) and squaramide (6) derivatives were designed, respectively, through the strategy of scaffold morphing and hydrogen-bond introduction, using the selective Mtb ATP synthase inhibitor compound 2 as the lead compound. The result demonstrated that diamino substituted cyclobut-3-ene-1,2-dione compounds 6ab and 6ah displayed good to excellent in vitro anti-TB activities (MIC 0.452-0.963 µg/mL) with low cytotoxicity (IC50 > 64 µg/mL). In addition, not only did compound 6ab show effective activity against clinically isolated resistant strains, it also revealed good druggability profiles including improved metabolic stability, no hERG channel inhibition potential, and acceptable oral bioavailability. The preliminary result of docking study and in vitro anti-bedaquiline-resistant strain test compared to compound 2 suggested that Mtb ATP synthase is most likely the target of compound 6ab. The structure-activity relationship laid a good foundation for the identification of novel squaramides as a potential treatment of drug-resistant tuberculosis.

Analytical and Sensory Characterization of the Stereoisomers of 3-Mercaptocycloalkanones and 3-Mercaptocycloalkanols.

3-Mercaptocycloalkanones and 3-mercaptocycloalkanols (chain lengths C5-C7) were obtained by addition of thioacetic acid to the respective 2-cycloalken-1-ones and subsequent enzyme-mediated hydrolysis and reduction with LiAlH4, respectively. The stereoisomers were separated via capillary gas chromatography using chiral stationary phases. Their configurations were determined based on 1H NMR data and enzyme-catalyzed kinetic resolutions. Odor thresholds and odor qualities were assessed by capillary gas chromatography/olfactometry. Compared to the analogous acyclic 4-mercapto-2-alkanones and 4-mercapto-2-alkanols, the cyclic polyfunctional thiols lacked fruity, tropical notes; the perceived odor properties ranged from cooked, roasted vegetables and meat types to onion-related notes. The odor thresholds of the enantiomers of the 3-mercaptocycloalkanones were mainly impacted by their ring size rather than their configuration. For the 3-mercaptocycloalkanols, the (S)-configuration at the stereogenic center bearing the thiol group and the relative configuration of the second asymmetric center with the hydroxyl group were of importance for low odor thresholds.