Multiple Parallel Reactions Research Articles

Acoustic levitation and manipulation of columns of droplets with integrated optical detection for parallelisation of reactions.

The most common methodology for performing multiple chemical and biological reactions in parallel is to use microtitre plates with either manual or robotic dispensing of reactants and wash solutions. We envision a paradigm shift where acoustically levitated droplets serve as wells of microtitre plates and are acoustically manipulated to perform chemical and biological reactions in a non-contact fashion. This in turn requires that lines of droplets can be levitated and manipulated simultaneously so that the same operations (merge, mix, and detect) can be performed on them in parallel. However, this has not been demonstrated until this work. Because of the nature of acoustic standing waves, a single focus has more than one trap, and can allow levitation of columns of droplets at the focal point and at half a wavelength above and below that point. Using this approach, we increased the number of acoustically levitated and merged droplets to 6 compared to 2 in the state-of-the-art. We showed that droplets in a column can be moved and merged with droplets in another column simultaneously and in a controlled manner to perform repeats and/or parallelisation of chemical and biological reactions. To demonstrate our approach experimentally, we built an acoustic levitator with top and bottom surfaces made of a 16 × 16 grid of 40 kHz phased array transducers and integrated optical detection system, studied two acoustic trap generation and movement algorithms, and performed an exemplar enzyme assay. This work has made significant steps towards acoustic levitation and manipulation of large numbers of droplets to eventually significantly reduce the use of the current state-of-the-art tools, microtitre plates and robots, for performing parallelised chemical and biological reactions.

Scalable droplet-based radiosynthesis of [18F]fluorobenzyltriphenylphosphonium cation ([18F]FBnTP) via a "numbering up" approach.

The [18F]fluorobenzyltriphenylphosphonium cation ([18F]FBnTP) has emerged as a highly promising positron emission tomography (PET) tracer for myocardial perfusion imaging (MPI) due to its uniform distribution in the myocardium and favorable organ biodistribution demonstrated in preclinical studies. However, a complex and low-efficiency radiosynthesis procedure has significantly hindered its broader preclinical and clinical explorations. Recently, Zhang et al. developed a pinacolyl arylboronate precursor, enabling a one-step synthesis process that greatly streamlines the production of [18F]FBnTP. Building upon this progress, our group successfully adapted the approach to a microdroplet reaction format and demonstrated improved radiosynthesis performance in a preliminary optimization study. However, scaling up to clinical dose amounts was not explored. In this work, we demonstrate that scale-up can be performed in a straightforward manner using a "numbering up" strategy (i.e. performing multiple droplet reactions in parallel and pooling the crude products). The resulting radiochemical yield after purification and formulation was high, up to 66 ± 1% (n = 4) for a set of experiments involving pooling of 4 droplet reactions, accompanied by excellent radiochemical purity (>99%) and molar activity (339-710 GBq μmol-1). Notably, we efficiently achieved sufficient activity yield (0.76-1.84 GBq) for multiple clinical doses from 1.6 to 3.7 GBq of [18F]fluoride in just 37-47 min.

Enhancing DNA-based nanodevices activation through cationic peptide acceleration of strand displacement.

Dynamic DNA-based nanodevices offer versatile molecular-level operations, but the majority of them suffer from sluggish kinetics, impeding the advancement of device complexity. In this work, we present the self-assembly of a cationic peptide with DNA to expedite toehold-mediated DNA strand displacement (TMSD) reactions, a fundamental mechanism enabling the dynamic control and actuation of DNA nanostructures. The target DNA is modified with a fluorophore and a quencher, so that the TMSD process can be monitored by recording the time-dependent fluorescence changes. The boosting effect of the peptides is found to be dependent on the peptide/DNA N/P ratio, the toehold/invader binding affinity, and the ionic strength with stronger effects observed at lower ionic strengths, suggesting that electrostatic interactions play a key role. Furthermore, we demonstrate that the cationic peptide enhances the responsiveness and robustness of DNA machinery tweezers or logic circuits (AND and OR) involving multiple strand displacement reactions in parallel and cascade, highlighting its broad utility across DNA-based systems of varying complexity. This work offers a versatile approach to enhance the efficiency of toehold-mediated DNA nanodevices, facilitating flexible design and broader applications.

Targeted Glycoproteomics Analysis Using MRM/PRM Approaches.

MS-target analyses are frequently utilized to analyze and validate structural changes of biomolecules across diverse fields of study such as proteomics, glycoproteomics, glycomics, lipidomics, and metabolomics. Targeted studies are commonly conducted using multiple reaction monitoring (MRM) and parallel reaction monitoring (PRM) techniques. A reliable glycoproteomics analysis in intricate biological matrices is possible with these techniques, which streamline the analytical workflow, lower background interference, and enhance selectivity and specificity.

Targeted Analysis of Permethylated N-Glycans Using MRM/PRM Approaches.

Targeted mass spectrometric analysis is widely employed across various omics fields as a validation strategy due to its high sensitivity and accuracy. The approach has been successfully employed for the structural analysis of proteins, glycans, lipids, and metabolites. Multiple reaction monitoring (MRM) and parallel reaction monitoring (PRM) have been the methods of choice for targeted structural studies of biomolecules. These target analyses simplify the analytical workflow, reduce background interference, and increase selectivity/specificity, allowing for a reliable quantification of permethylated N-glycans in complex biological matrices.

Thermal degradation of virgin and waste plastics: Estimation of kinetic and thermodynamic parameters using model‐free iso‐conversional methods

AbstractKinetic triplets—apparent activation energy (Ea), pre‐exponential factor (A), and the reaction model—were estimated for the thermal degradation of three primary virgin and waste plastics, as well as mixed plastics waste. Model‐free iso‐conversional FWO, KAS, Starink, Kissinger and Vyzovkin and Friedman methods were employed for the kinetic analysis. The apparent activation energy was determined by the integral methods as 206.5‐209.1 kJ mol−1 and 195.6‐198.8 kJ mol−1 for the virgin and waste high‐density polyethylene (HDPE), 211.6‐214.1 kJ mol−1 and 183.1‐186.6 kJ mol−1 for the virgin and waste polypropylene (PP), 144.0‐163.1 kJ mol−1 and 159.7‐167.1 kJ mol−1 for the virgin and waste polystyrene (PS), and 173.6‐178.9 kJ mol−1 for the mixed plastics waste respectively. Ea was found to follow the trend HDPE > PP > PS with higher values for HDPE and PP virgin samples than that for their waste and marginally smaller for the virgin PS than its waste. Degradation of all plastic samples followed Avrami‐Erofeev equation with n varying between 1.0 and 1.8. The effect of conversion on Ea suggested the degradation of both virgin and waste HDPE to consist of multiple parallel reactions while that of others to be more complex. FTIR analysis of the evolved gases was used to explain the possible reaction mechanism. A small difference between the enthalpy change and the apparent activation energy (6‐7 kJ mol−1) for all plastic samples indicated favourable pyrolysis reactions. The estimated kinetic parameters and thermodynamic properties showed the stability of different plastics as HDPE > PP > PS.

Production of diacetates from propenylphenols: A one-pot two-step approach involving hydroformylation/hydrogenation/O-acylation

A one-pot two-step approach for the synthesis of diacetate esters from propenylphenols was developed. This protocol involves the functionalization of the propenylphenol in two remote sites, performing multiple consecutive and parallel reactions: hydroformylation of the C-C double bond, hydrogenation of the formed aldehyde, and the O-acylation of both phenolic and hydroxy groups of the resulting alcohol. For such a challenging transformation, specific catalytic systems had to be developed, involving Rh complexes and phosphorus(III) ligands for the tandem hydroformylation/hydrogenation, along with 4-dimethylaminopyridine (an organocatalyst) to promote the acylation step by Ac2O. As the presence of Ac2O before the hydrogenation step leaded to undesired side reactions, a one-pot two-step protocol was developed to enhance the selectivity. Eventually, the method allowed to obtain diacetate esters, which are potentially valuable as flavor and fragrance ingredients, from propenylphenols in good to excellent yields (82–96 %).

A cascaded modeling approach for comprehensive reaction state perception of a hydrometallurgical reactor

A hydrometallurgical reactor is the central production unit in a hydrometallurgy process. Due to the correlation between multiple parallel reactions and feeding condition fluctuations, modeling the outlet technical indicator alone is insufficient to express the highly informative reaction state comprehensively. This paper proposes a cascaded modeling approach for comprehensive reaction state perception of a hydrometallurgical reactor by considering the feeding conditions, operation modes, outlet technical indicators, and their relations. First, propose a perception model based on the information of two adjacent reactors for feeding condition perception. Second, develop an online operating mode perception model, combining dynamic feature extraction methods based on dynamic inner principal component analysis and mechanism knowledge. Finally, an outlet technical indicator perception model integrates mechanism and data features for multiple operation modes. The simulation results reveal that the proposed model can comprehensively describe the reaction state and guide on-site control.

Improved and generalized criteria for the instantaneous regime for multiple parallel Gas-Liquid reactions

The classic criteria to determine if a second-order irreversible gas–liquid reaction (AG+νBBL→νCCL) proceeds in the instantaneous regime are based on the Hatta number, HaA, and the infinite enhancement factor, EA,∞, i.e., HaA>2 and HaA≫EA,∞-1. There is no consensus, however, with respect to the latter threshold value and this work shows that it highly depends on the considered reactant concentrations and rate coefficients, in particular when the non-volatility assumption of the liquid phase component is relieved. Generalizing the original derivation yields an extended expression, which is condensed into a new dimensionless number, φA,∞, and allows to rewrite the second criterion as φA,∞>15, where φA,∞=HaAEA,∞-1-EA,∞. Next, it is demonstrated that a breakthrough of the gas-phase reactant into the bulk-liquid is readily observed at high interface concentrations of the gas-phase reactant with respect to the bulk concentration of the liquid-phase reactant, even though the classic criteria have been met. Such a situation is quite common in the chemical industry, e.g., in case of the selective reactive removal of an impurity (BL) from a process stream containing a valuable product by a soluble gaseous component (AG). The root cause of this deviating behavior results from the position of the reaction plane and an additional criterion, φB,∞>15, is needed to resolve this. As such, the set of improved criteria are necessary and sufficient to describe the instantaneous regime for any position of the reaction plane. To conclude, a methodology is presented to apply the modified criteria to multiple parallel reactions, and the validity of these improved and generalized criteria is numerically demonstrated.

Tackling functional redundancy of Arabidopsis fatty acid elongase complexes.

Very-long-chain fatty acids (VLCFA) are precursors for various lipids playing important physiological and structural roles in plants. Throughout plant tissues, VLCFA are present in multiple lipid classes essential for membrane homeostasis, and also stored in triacylglycerols. VLCFA and their derivatives are also highly abundant in lipid barriers, such as cuticular waxes in aerial epidermal cells and suberin monomers in roots. VLCFA are produced by the fatty acid elongase (FAE), which is an integral endoplasmic reticulum membrane multi-enzymatic complex consisting of four core enzymes. The 3-ketoacyl-CoA synthase (KCS) catalyzes the first reaction of the elongation and determines the chain-length substrate specificity of each elongation cycle, whereas the other three enzymes have broad substrate specificities and are shared by all FAE complexes. Consistent with the co-existence of multiple FAE complexes, performing sequential and/or parallel reactions to produce the broad chain-length-range of VLCFA found in plants, twenty-one KCS genes have been identified in the genome of Arabidopsis thaliana. Using CRISPR-Cas9 technology, we established an expression platform to reconstitute the different Arabidopsis FAE complexes in yeast. The VLCFA produced in these yeast strains were analyzed in detail to characterize the substrate specificity of all KCS candidates. Additionally, Arabidopsis candidate proteins were transiently expressed in Nicotiana benthamiana leaves to explore their activity and localization in planta. This work sheds light on the genetic and biochemical redundancy of fatty acid elongation in plants.

Absolute Quantitative Targeted Proteomics Assays for Plasma Proteins.

Preclinical and clinical trials require rapid, precise, and multiplexed analytical methods to characterize the complex samples and to allow high-throughput biomarker monitoring with low consumption of sample material. Targeted proteomics has been used to address these challenges when quantifying protein abundances in complex biological matrices. In many of these studies, blood plasma is collected either as the main research or diagnostic sample or in combination with other specimens. Mass spectrometry (MS)-based targeted proteomics using multiple reaction monitoring (MRM) or parallel reaction monitoring (PRM) with stable isotope-labeled internal standard (SIS) peptides allows robust characterization of blood plasma protein via absolute quantification. Compared to other commonly used technologies like enzyme-linked immunosorbent assay (ELISA), targeted proteomics is faster, more sensitive, and more cost-effective. Here we describe a protocol for the quantification of proteins in blood plasma using targeted MRM proteomics with heavy-labeled internal standards. The 270-protein panel allows rapid and robust absolute quantitative proteomic characterization of blood plasma in a 1h gradient. The method we describe here works for non-depleted plasma, which makes it simple and easy to implement. Moreover, the protocol works with the two most commonly used blood plasma collection methods used in practice, namely, either K2EDTA or sodium citrate as anticoagulants.

Progress in Targeted Mass Spectrometry (Parallel Accumulation-Serial Fragmentation) and Its Application in Plasma/Serum Proteomics.

Targeted mass spectrometry using multiple reaction monitoring (MRM) or parallel reaction monitoring (PRM) has been commonly used for protein biomarker validation in plasma, serum, or other clinically relevant specimens due to its high specificity, selectivity, and multiplexing capability compared with immunoassays. As the emerging mode termed parallel accumulation-serial fragmentation (prmPASEF) significantly improved analyte throughput (100-1000), sensitivity (attomole level), and acquisition speed, it promises to broaden the application of targeted mass spectrometry to simultaneous biomarker discovery and validation with high accuracy. Here, we summarize the general approach of the MRM and PRM techniques used for serum/plasma proteomics and describe a detailed step-by-step procedure for the development of MRM/PRM assays for secreted proteins.

A giant polyoxomolybdate molecular catalyst with unusual Mo6+/Mo5+ synergistic mechanism for oxidation of hydroxyfurfural under atmospheric pressure

Selective oxidation of 5-hydroxymethylfurfural (HMF) under atmospheric conditions is challenging due to the slow reaction rate and multiple parallel reaction routes. This work reports a green approach for selective oxidation of HMF to 2,5-diformylfuran (DFF) by using a giant Keplerate-type polyoxometalate of [(NH4)42[MoVI72MoV60O372(CH3COO)30(H2O)72] (Mo132). Mo132 features extraordinary catalytic activity under atmospheric and even anaerobic conditions, achieving the conversion of 99.2% with DFF selectivity of 100%. Mo132 also shows outstanding recyclability with the activity decreasing by only 3.4% after five recycle tests. The intermediate valence state content of Mo5+ in Mo132 is about 46%, which displays superior catalytic activities during the reactions. Mechanism exploration firstly indicates that the proposed proton coupled electron transfer occurs on special terminal oxygen atoms in Mo6+ sites being surrounded by Mo5+ species. This unveils a new Mo6+/Mo5+ synergistic effect to enhance the efficiency for catalyzing the oxidation of HMF. This work expands the application of high-nuclear molybdenum clusters in catalysis, and supplies a new strategy for the justified design and synthesis of POMs-based catalysts in biorefinery.

Tuning product selectivity in nitrobenzene reduction over a single Bi2MoO6 photocatalyst in one pot: Mechanisms and roles of reaction compositions

Poor product selectivity of metal oxide photocatalysts is one of crucial issues limiting their application in photocatalytic organic synthesis particularly when multiple parallel reactions as well as several intermediates and products are involved, as in the reduction of nitrobenzene (NB) in this present study. Accordingly, catalyst modification is often needed. Herein, we first demonstrate that without catalyst modification it is feasible to control product selectivity over a single bismuth molybdate photocatalyst to selectively prepare three different valuable compounds including aniline (AN), azobenzene (AZO) and azoxybenzene (AZX) with high efficacy. Two widely used bismuth molybdate photocatalysts, namely Bi2MoO6 and Bi4MoO9, were studied and compared. Bi2MoO6 offers better visible-light-driven photocatalytic performance than Bi4MoO9 partly due to its narrow band gap energy and efficient charge carrier separation and transfer as evidenced from UV–vis DRS, EIS, and transient photocurrent studies. The roles of hydrazine hydrate, alcohol solvent, and KOH additive on the transfer hydrogenation of NB were examined and their concentrations were optimized to solely obtain the three different products with excellent selectivity (>98%). Based on UV–vis DRS and Mott-Schottky analysis, the band energy level of Bi2MoO6 and plausible reactions at solid–liquid interface are proposed. The capability to control product selectivity over a single photocatalyst in one pot demonstrated in this work would make the process more practical especially for continuous flow photochemical systems.

Review on Development System of Traceability in Dairy Processing

The application of molecular methods is widely implemented in the traceability systems in the food sector, covering many types of food, as it is shown in this review. The rapid implementation of traceability systems in the food system is due to these techniques with high specificity, sensitivity, efficiency, and speed. In addition, compared with protein-based techniques, DNA-based techniques can be applied to any type of product, regardless of the treatment of processing to which it has been subjected. Future trends in the development of molecular or genetic tools for food traceability are focused on the search of techniques to obtain more information in the shortest time possible. Techniques that allow the identification, both at the species and population level, also facilitate the determination of the geographic origin. At present, one of the most promising techniques is the Digital PCR (dPCR), which allows the analysis of samples containing mixtures of species with high sensitivity and in a single assay, making multiple reactions in parallel through a nanofluidic chip. The application of emerging technologies, microfluidics, and nanotechnology in the development of molecular methods will obtain greater sensitivity, discriminatory power, reproducibility, and speed, thus increasing its potential in the traceability of the food sector.

Targeted liquid chromatography-tandem mass spectrometry analysis of proteins: Basic principles, applications, and perspectives.

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is now the main analytical method for the identification and quantification of peptides and proteins in biological samples. In modern research, identification of biomarkers and their quantitative comparison between samples are becoming increasingly important for discovery, validation, and monitoring. Such data can be obtained following specific signals after fragmentation of peptides using multiple reaction monitoring (MRM) and parallel reaction monitoring (PRM) methods, with high specificity, accuracy, and reproducibility. In addition, these methods allow measurement of the amount of post-translationally modified forms and isoforms of proteins. This review article describes the basic principles of MRM assays, guidelines for sample preparation, recent advanced MRM-based strategies, applications and illustrative perspectives of MRM/PRM methods in clinical research and molecular biology.

Effects of surface species and homogeneous reactions on rates and selectivity in ethane oxidation on oxide catalysts

AbstractSelective alkane oxidations on metal oxide catalysts involve complex mechanisms with multiple reactions in series and parallel, different types of reduced and oxidized surface species, and potential contributions from gas‐phase reactions. Here, kinetics and thermodynamics of elementary steps involved in C2H6‐O2 reactions on SiO2‐supported small vanadium oxide domains are determined using density functional theory. These surface reactions together with gas‐phase mechanisms are incorporated in kinetic simulations to determine how surface and gaseous reactions interact and contribute to rates and selectivity. The results show that gas‐phase reactions within pore volumes in contact with the catalyst contribute significantly to C2H6 activation rates, even at conditions where gas‐phase reactions in empty volumes without catalyst are negligible. The majority of C2H6 activations occur on the surface, via H abstraction by vanadium oxo species present at terminal lattice oxygens. The gas‐phase activations via H‐abstraction by OH radicals also exhibit significant contributions. The reduced centers formed by reactions at vanadium oxo species are re‐oxidized rapidly and, therefore, are present in very small concentrations at reaction conditions. The re‐oxidation steps lead to the formation of HO2 radicals and surface peroxo species that are also rapidly consumed and are present in small concentrations. The peroxo species preferentially convert C2H4 to its epoxide product and influence selectivity even at low concentrations. The gas‐phase reactions decrease the concentrations of peroxo species and improve selectivity slightly. The effects of reaction conditions and catalyst site density provide further insights into how factors beyond conversions at lattice oxygens influence rates and selectivity in alkane oxidation reactions of significant industrial importance.

Analytical solution for multi-component pyrolysis simulations of thermal protection materials

This paper provides the analytical solution to a one-parameter Šesták–Berggren kinetic model for the thermoanalytical study of pyrolysis reactions involving multiple independent parallel reactions. Such multiple independent parallel reactions are widely used, for instance, in the modeling of the pyrolysis of thermal protection materials used in heatshields for spacecraft during the atmospheric entry phase. Solving inverse problems to infer parameters of the kinetic model through optimization techniques or Bayesian inference methods for uncertainty quantification may require a large number of evaluations of the response and its sensitivities (derivatives with respect to parameters). Moreover, in the case of kinetic equations, the Arrhenius parameters can exhibit strong dependence that can require further model evaluations for an accurate parameter calibration. The interest of this analytical solution is to reduce computation cost while having high accuracy to perform parameter calibration from experiments and sensitivity analysis. We propose to use exponential–integral functions to express the solution of the temperature integral, and we derive the analytical solution and its sensitivities for the parallel reaction model both for constant temperature (isothermal) and for constant heating rate conditions. The solution is validated on a six-equation model using parameters inferred in a previous work from the experimental data of the pyrolysis of a phenolic-impregnated carbon ablator material, and we compare the computational cost and accuracy of the implemented analytical solution with a numerical solution. Our results show that the use of such analytical solution with an accurate computation of the exponential–integral function significantly reduces the computational cost compared to the numerical solution.

Thin-film-transistor digital microfluidics for high value in vitro diagnostics at the point of need.

The latest developments in thin-film-transistor digital-microfluidics (TFT-DMF, also known by the commercial name aQdrop™) are reported, and proof of concept application to molecular diagnostics (e.g. for coronavirus disease, COVID-19) at the point-of-need demonstrated. The TFT-DMF array has 41 thousand independently addressable electrodes that are capable of manipulating large numbers of droplets of any size and shape, along any pathway to perform multiple parallel reactions. Droplets are continually tracked and adjusted through closed-loop feedback enabled by TFT based sensors at each array element. The sample-to-answer molecular in vitro diagnostic (IVD) test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) includes nucleic acid extractions from saliva, removal of dsDNA and quantitative reverse transcription polymerase chain reaction (RT-PCR). This proof of concept illustrates how the highly configurable TFT-DMF technology can perform many reactions in parallel and thus support the processing of a range of sample types followed by multiple complex multi-step assays.

High-Throughput Mass Spectrometry Screening Platform for Discovering New Chemical Reactions under Uncatalyzed, Solvent-Free Experimental Conditions.

A gas-phase high-throughput reaction screening platform was developed for the first time to study chemical structures of closely related functional groups and for the discovery of novel organic reaction pathways. Experiments were performed using the contained atmospheric pressure chemical ionization (APCI) source that enabled nonthermal, nonequilibrium plasma chemistry to be monitored by mass spectrometry (MS) in real time. This contained-APCI MS platform allowed an array of reagents to be tested, resulting in the studies of multiple gas-phase reactions in parallel. By exposing headspace vapor of the selected reagents to corona discharge, solvent-free Borsche-Drecsel cyclization reaction, Katritzky chemistry, and Paal-Knorr pyrrole synthesis were examined in the gas phase, outside the high vacuum environment of the mass spectrometer. A new radical-mediated hydrazine coupling reaction was also discovered, which provided a selective pathway to synthesize secondary amines without using a catalyst. The mechanisms of these atmospheric pressure gas-phase reactions were explored through the direct capture of intermediates and via comparison with the corresponding bulk solution and droplet-phase reactions.