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Un système microfluidique à onde élastique de surface a été développé dans le but de réaliser une réaction d'amplification de brins d'ADN par PCR. Nous avons principalement étudié la température et l'uniformité de l'échauffement des gouttes irradiées par des ondes de type Rayleigh. Ces dernières sont générées à la surface d'un substrat piézoélectrique de Niobate de Lithium (LiNbO3). Nous avons pensé un système consommant le moins d'énergie électrique possible pour atteindre les températures désirées et permettant une meilleure uniformité de la température des gouttes. Pour cela, un dispositif à transducteur enterré a été réalisé sous une couche isolante de silice. Les gouttes sont ainsi directement posées sur le transducteur ce qui limite les pertes et améliore la répartition de la chaleur au sein des gouttes. Nous avons ensuite vérifié que les réactifs de la PCR ne sont pas affectés par les ondes de Rayleigh ce qui laisse présager que la PCR peut être réalisée à l'aide d'un système d'échauffement par ondes de Rayleigh. Par ailleurs, le déplacement de goutte sur ce type de substrat de LiNbO3 est important pour des applications de type laboratoire sur puce. Ce substrat ayant des propriétés hydrophiles, des revêtements ont été développés afin de minimiser la force nécessaire à l'actionnement des gouttes. Dans ces travaux, nous proposons un nouveau type de couche à base de copolymère P(VDF-TrFe) dont la fabrication est simplement réalisée par dissolution et étalement par spin-coating. Nous avons montré que ce type de couche n'affecte que très peu la propagation des ondes de Rayleigh et les propriétés hydrophobes sont équivalentes à d'autres revêtements / In this work, a microfluidic system based on surface acoustic wave has been developed in order to achieve the amplification of DNA strands by temperature cycling (PCR). We studied mainly the temperature and the heat uniformity of microdroplets irradiated by Rayleigh waves. These waves are generated at the surface of a lithium niobate substrate. We propose a system allowing better temperature uniformity within microdroplets with an optimal energy consumption. For this, a device with buried transducer has been developed under an insulating layer (Silice). The droplets are then placed directly on the transducer which limits losses and improves the distribution of heat within the microdroplets. We then verified that the PCR reagents are not affected by the Rayleigh waves which suggests that PCR can be performed using a heating system by Rayleigh waves. Moreover, the move of microdroplets on this kind of LiNbO3 substrate is important for lab on chip applications. This substrate having hydrophilic properties, some coatings have been developed to minimize the required force to actuate the microdroplets. In this work, we developed a new hydrophobic layer based on copolymer P(VDF-TrFe) whose production is simply made by dissolving and spreading by spin-coating. We have shown that this kind of layer is compatible with Rayleigh waves and that the hydrophobic properties are equivalent to other coatings

<p>The rapid analysis of complex samples using mass spectrometry (MS) provides valuable information in both point-of-care (e.g. drug testing) and laboratory-based applications, including the generation of spectral libraries for classification of biosamples, the identification of biomarkers through large-scale studies, as well as the synthesis and bioactivity assessments of large compound sets necessary for drug discovery. In all these cases, the inherent speed of MS is attractive, but rarely fully utilized due to the widespread use of sample purification techniques prior to analysis. Ambient ionization methodologies can help circumvent this drawback by facilitating high-throughput qualitative and quantitative analysis directly from the complex samples without any need for work-up. For instance, the use of swabs or paper substrates allows for rapid identification, quantification, and confirmation, of drugs of abuse from biofluids or surfaces of forensic interest in a matter of minutes, as described in the first two chapters of this dissertation. Faster analysis can be achieved using an automated desorption electrospray ionization (DESI) platform which allows for the rapid and direct screening of complex-sample microarrays with throughputs better than 1 sample per second, giving access to rich spectral information from tens of thousands of samples per day. The development of the bioanalytical capabilities of this platform, particularly within the context of drug discovery (e.g. bioactivity assays, biosample analysis), is described across most other chapters of this dissertation. The use of DESI, a contactless ambient ionization method developed in our laboratory and whose 20 years of history are overviewed in the introduction of this document, provides an additional advantage as the secondary microdroplets generated through the DESI process act as reaction vessels that can accelerate organic reactions by up to six orders of magnitude, facilitating on-the-fly synthesis of new compounds from arrays of starting materials. Unique implications of this microdroplet chemistry in the prebiotic synthesis of peptides and spontaneous redox chemistry at air-solution interfaces, together with its practical applications to the synthesis of new drug molecules, are also overviewed. The success obtained with the first automated DESI-MS system, developed within the DARPA Make It program, led to increased interest in a new-generation platform which was designed over the past year, as overviewed in the last section of this dissertation, and which is currently being installed for validation prior to the transfer of the technology to NCATS, where we anticipate it will make a significant impact through the consolidation and acceleration of the early drug discovery workflow.</p>

<p dir="ltr">Mass spectrometry (MS) has long been recognized as a technology for bioanalysis. However, this thesis focuses on exploiting mass spectrometry for chemical reactions. The work described here covers the (a) investigation of chemistry at interfaces by MS, (b) utilization of MS to accelerate drug discovery processes, and (c) applications of MS techniques for organic synthesis. MS techniques are used to scrutinize the distinctive chemistry and super acidity mechanisms at the gas/liquid interfaces by reacting carbon dioxide (gas phase) with amines (solution, in droplets). The intriguing trace water effect in creating this unique environment at the interfaces is described. A systematic survey of reactions promoted by glass microspheres at liquid/solid interfaces is conducted, revealing that glass surface can act as strong base to speed up reactions. Additionally, the ability of glass surface to degrade biomolecules is revealed, which has implications for bioanalysis. Desorption electrospray ionization (DESI), an ambient ionization method, can be used as a rapid analytical technique for the direct analysis of complex reaction mixtures or bioassays without sample workup. Moreover, DESI can also be used as a small-scale synthetic tool due to accelerated reactions in generated microdroplets. These characteristics make DESI a core technology for high-throughput (HT) experimentation that prioritizes speed to achieve three major roles. <b>(i) HT reaction screening</b> leverages the reaction acceleration phenomenon for rapid chemical space exploration, especially for the late-stage diversification of drug molecules. The entire process, from sampling the reaction mixture by droplets to on-the-fly chemical transformation during millisecond timescales to analysis by MS, achieves an overall throughput of one reaction per second in an integrated fashion. Diverse chemical transformations for various functional groups were achieved, with over 10⁴ reactions explored and over 10³ analogs identified within three hours. <b>(ii) HT synthesis</b> is achieved using an automated homebuilt array-to-array transfer system. The synthetic system uses DESI microdroplets for transferring reaction mixtures from a precursor array to products on a product array. High conversions of diverse reactions with synthetic throughput of 0.2-0.02 Hz and scale of ng-µg (pmole-nmole) in a spatially resolved manner are demonstrated. Hundreds of modified bioactive molecules are generated in an array format, and the spatial distribution of the products is visualized by mass spectrometry imaging. <b>(iii) HT bioassays</b> are demonstrated by combining the label-free nature of MS with the high-speed analysis of DESI. The contactless feature, with high tolerance towards complex mixtures, allows direct bioassays with minimal sample preparation. An opioid receptor binding assay is described with an evaluation of the binding affinity of synthesized opioid analogs. An on-surface enzymatic assay is developed for measuring the bioactivity of deposited molecules <i>in situ</i>. The consolidation of (i) HT reaction screening, (ii) HT synthesis, and (iii) HT bioassays by a single but versatile technique, HT-DESI, can expedite the early drug discovery process. For applications, MS technologies are utilized to probe reactive intermediates and the reaction mechanisms of palladium-catalyzed coupling reactions. MS is also used to explore chemical reactions for natural products, rapidly generating analogs for bioactivity evaluation and benefiting bioanalysis through the discovery of derivatization reactions. HT tandem MS is demonstrated to be powerful for structural elucidation and reaction site identification.</p>

In dieser Doktorarbeit wurde eine analytische Methode zur Charakterisierung metallischer Nanopartikel (NPs) entwickelt und die Methode bei der Untersuchung natürlicher Proben angewendet. Mit einem analytisches System bestehend aus einem Mikrotropfengenerator (microdroplet generator, MDG) zusammen mit einem pneumatischen Zerstäuber und einem induktiv gekoppeltem Plasma-Massenspektrometer (ICP-MS) konnte eine quantitative und qualitative Charakterisierung von NPs durchgeführt werden. Der MDG wurde verwendet um die Kalibrierungsfunktion für die massenspektrometrische Quantifizierung der Metalle in den Nanopartikelproben, die über den pneumatischen Zerstäuber eingeführt wurden, einzurichten. Der Hauptvorteil dieser Anordnung besteht darin, dass mit dem MDG für jedes Metall Tropfen einer gewünschten Größe hergestellt werden können und eine 100 %-ige Transporteffizienz gegeben ist. Die eingeführte Masse korrelierte mit der Signalintensität von Nanopartikeln, so dass die mit dem MDG generierten Tropfen für die Kalibrierung verwendet werden konnten ohne dass Referenzmaterial erforderlich war. Die aufwändige und fehleranfällige Bestimmung der Effizienz eines Zerstäubers, die für die Bestimmung des Metallgehaltes von NPs mittels eines Einzelpartikel-ICP-MS (spICP-MS) erforderlich ist, konnte dadurch vermieden werden. Unter Anwendung dieser dualen Einführungsmethode wurden Größen und Konzentrationen einer Reihe von Standard Silber (Ag) NPs und Referenz Gold (Au) NPs mit hoher Genauigkeit bestimmt. Zusätzlich wurde mit einem neuen kommerziell verfügbaren ICP-Flugzeitmassenspektrometer (ICP-TOF-MS) Ag und Au NPs in unterschiedlichen Matrices charakterisiert: in verschiedenen Salzsäure (HCl)- und Salpetersäure (HNO3)- Konzentrationen und in Gegenwart verschiedener Elemente. Bei den unterschiedlichen Matrices war die Größenbestimmung innerhalb der gegebenen Standardabweichungen korrekt. / In this doctoral thesis an analytical method for characterising metal nanoparticles (NPs) was developed and its application for investigating natural samples verified. An analytical system consisting of a microdroplet generator (MDG) used in combination with a pneumatic nebuliser (PN) and an inductively coupled plasma mass spectrometer (ICP-MS) proved capable of quantitatively and qualitatively identifying NPs. The MDG was used to establish the calibration function for mass quantification of the metal present in the sample NPs introduced via the PN. The major advantage of this configuration is that the MDG generated droplets of tailored size for any given metal while offering a 100 % transport efficiency. The introduced mass correlated with signal intensities of NPs and thus the microdroplet generated droplets could be used for calibration purposes without the need for any reference material. Thus, the tedious and error-prone nebuliser efficiency determination step that is required when determining the NP metal content using the single particle mode ICP-MS (spICP-MS) approach, could be avoided. With this dual sample introduction method, the sizes and concentrations of a range of standard silver (Ag) NPs and gold (Au) reference NPs were determined with high accuracy. Additionally, together with a new commercially available ICP-time of flight-MS (ICP-TOF-MS) the characterisation of Ag- and Au-NPs was carried out in various matrices: In hydrochloric (HCl) and nitric acid (HNO3) at a range of concentration and in different elemental environments. In the presence of matrices, it was found that the size characterisation of the NPs is correct within the standard deviation.